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GCr15SiMn is a kind of bearing steel material with good physical and mechanical properties, which is broadly used in aerospace, automotive, and other advanced manufacturing fields. However, the harsh environment of the ordinary grinding (OG) process, including high grinding forces, high grinding temperatures, fast grinding wheel wear, and severe chip sticking, has led to the GCr15SiMn material being unable to be widely adopted. This paper introduces ultrasonic vibration grinding (UVG) technology to improve its machined surface quality. First, the formation mechanism of the two grinding methods was analyzed theoretically, and surface morphology of ultrasonic vibration grinding and ordinary grinding processing was analyzed by numerical simulation, while the effects of different processing variables on surface roughness were investigated experimentally. The results show that the simulated morphology is consistent with the experimental morphology. The grinding marks of UVG are wavy, wide, and shallow, and OGs are horizontal, with narrow and deep grooves. Also it was found that ultrasonic vibration grinding could improve the quality of the surface with lower roughness than normal grinding, and the surface roughness was reduced by more than 27%. The feed rate and spindle speed had significant effects on the surface roughness, accounting for 44.37% and 33.66%, respectively. [ABSTRACT FROM AUTHOR]

Ultrasonic vibration-assisted (UVA) cutting is an advanced technique to improve the machinability and productivity of difficult-to-machine materials. This paper aims to assess the cutting performance of ultrasonic vibration-assisted milling (UVAM) technique and conventional milling (CM) in side milling of Ti–6Al–4 V. Tool trajectory and instantaneous chip thickness are calculated considering tool runout, vibration, and deflection. The geometric-kinematic-dynamic surface topography matrix and its corresponding material elastic recovery height matrix are reconstructed based on tool trajectory and cutting thickness, which are then summed to obtain the geometric-kinematic-dynamic-physical surface topography matrix. Finally, roughness parameters Ra and Rz are predicted based on the final reconstructed physical surface topography matrix. Experimental results show that Ra and Rz of UVAM are on average 26 and 39% greater, respectively, compared to CM due to the presence of high-frequency ultrasonic vibration-induced texture patterns in the feed grooves. The average prediction error for Ra and Rz is 23%, proving the validity of the prediction model. UVAM reduces the radial and tangential cutting force coefficients and ploughing force coefficients compared to CM due to the separation and impact effect of ultrasonic vibration. However, UVAM leads to an increase in the axial ploughing force coefficient because ultrasonic vibration introduces relative motion and friction between the tool and the workpiece in the axial direction. [ABSTRACT FROM AUTHOR]

Cobalt-based superalloys are widely used in hot-end components of gas turbines due to their excellent elevated temperature mechanical properties. At present, cobalt-based superalloys are usually machined under cutting fluid, which will seriously pollute the environment and harm human health. Cryogenic cutting technology uses liquid nitrogen, supercritical carbon dioxide, etc. as the cooling medium, which has the advantages of environmental protection and energy conservation. In this paper, the cryogenic mechanical properties of cobalt-based superalloy GH605 were investigated, and then the cutting experiments were conducted under three different cooling and lubrication methods (flood condition, cryogenic minimum quantity lubrication, and liquid nitrogen) to investigate the cryogenic machinability and machining sustainability of GH605. The results show that cryogenic temperature can reduce the plasticity of GH605 but has little effect on the compressive yield strength and compressive strength. Compared with the cutting fluid, the cutting force of liquid nitrogen is reduced by up to 72.2%, the cutting-specific energy is reduced by about 83.9%, and the concentration of particulate matter such as PM2.5 generated during the processing can be decreased by more than 60%. The surface finish and consistency of cryogenic minimum quantity lubrication are better; the surface roughness is reduced by 0.4 ~ 20.4% at different cutting speeds. When the feed speed is greater than 0.10 mm/r, the work hardening degree decreases by 0.8 ~ 19.7%. Under the two cooling strategies, the chip surface is smooth and flat, chip breaking property is improved, but the machining noise is more than 100 dB. [ABSTRACT FROM AUTHOR]

Due to the enclosed working environment and inadequate cooling, it is easy to produce excessive local temperatures in the double-face grinding machining process. Excessive local temperatures lead to a number of issues, including grinding wheel wear, workpiece burns, and surface quality degradation. In order to reduce the temperature with little coolant, a study on coolant distribution is necessary. This paper studies the effects of grinding wheel speed and workpiece speed on the coolant distribution law. The unidirectional flow field model in double-face grinding is established based on the contact equation of computational fluid dynamics, the Navier‒Stokes equation, and the turbulence equation. This model also considers the pores on the grinding wheel surface, the equivalent height of the abrasive particles, the geometric boundary, and the equivalent gap between the workpiece and the wheel. The results show that the component surface fluid velocity gradually rises from the inner to the outside diameter of the grinding wheel. The grinding area pressure distribution in different parameters is analyzed. The variance analysis of coolant distribution is carried out. It is found that there is a positive linear correlation between the grinding fluid flowing into the grinding zone and the grinding wheel speed. With the increase of wheel speed, the more liquid concentrates on the area where the coolant enters. And it is observed that 60 rad/s wheel speed leads to a more even coolant distribution and a flatter machined surface. [ABSTRACT FROM AUTHOR]

Ultrasonic vibration–assisted core drilling has achieved some beneficial results in carbon fiber–reinforced plastics (CFRP) hole machining. Among them, longitudinal-torsional ultrasonic-assisted core drilling (LTUACD) shows more significant advantages in decreasing cutting force and reducing delamination defects and other aspects compared to longitudinal ultrasonic-assisted core drilling (LUACD). However, the reduction mechanism of cutting force and delamination defects in LTUACD is still not clear enough. Therefore, this paper researched the machining performance of LTUACD of CFRP. Specifically, the cutting force in LTUACD of CFRP is analyzed based on hertz contact theory and indentation depth theory. Then, a series of experiments were conducted to verify the analysis. And delamination suppression mechanism was discussed from the aspects of surface morphology of hole wall, exit morphology of hole, and bottom surface morphology of blind hole. The results show that the cutting force is significantly reduced in LTUACD compared to conventional core drilling (CCD) and LUACD due to the additional torsional vibration of tool, which changes the contact state between abrasive grain and material. Therefore, the exit delamination is further suppressed. In addition, the adhesion phenomenon of chips on the tool is also reduced, which enhances the tool cutting ability to obtain even fiber fracture surfaces and greatly improves hole quality. [ABSTRACT FROM AUTHOR]

Micro-cutting is characterised by undeformed chip thicknesses in the micron range. This range leaves little choice of in situ observation techniques. One solution is therefore to observe these zones a posteriori after the cutting has been abruptly interrupted. This technique has proven to be very useful for conventional machining. This paper deals with the development of a quick-stop device dedicated to micro-cutting. The aim of this device is to observe cutting mechanisms and chip formation at this scale in order to enhance micro-cutting models. [ABSTRACT FROM AUTHOR]

The activity of part orientation is of crucial importance in terms of impact on the quality of parts in powder bed additive manufacturing. To support the decision-making of computer aided manufacturing (CAM) operators, several knowledge and software models are proposed. Even if they seem to help operators in orientation process, their operational effectiveness still needs to be scientifically assessed. This paper proposes to evaluate the efficiency of a part orientation software in assisting CAM engineers in part orientation choice. The related software is based on the mathematization of action rules issued from a knowledge model. The knowledge involved in carrying out the orientation activity is analyzed based on the users' expertise. To do this, an empirical approach based on a case study is made with participants of different levels of skills. Several design scenarios including various part typologies to be oriented are submitted to engineers, before their manufacturing with electron beam melting (EBM) technology. Two means of orientation are thus used for comparison, namely, a manual orientation and a computer-aided orientation software. Based on the orientation results, an analysis of the software usage is undertaken. As an underlying result of our study, we have come up with an evaluation approach that can be reused in other contexts and with other software. [ABSTRACT FROM AUTHOR]

Metal additive manufacturing has been pointed as the answer to reduce manufacturing time and cost for aeronautic parts with a high buy to fly ratio. The manufacturability of a part by additive manufacturing depends on important indicators that would allow it to be cost effective. One key indicator is the manufacturing time, which is highly dependent on an important factor: the interlayer time. The interlayer time is the time needed by the material to cool down to a chosen temperature, called interlayer temperature, that allows a new deposition of molten material. The interlayer temperature is defined by using time–temperature-transformation (TTT) diagrams, the final goal being to avoid the appearance of detrimental phases that could lead to a decrease in the material's mechanical properties. The interlayer temperature is intimately correlated with the cooling curve. The difficulty of predicting the cooling time is due to the influence of the part geometry, the deposition strategy, and the dimensions of the substrate. Their correlation needs to be understood in order to minimize the travel time (ttravel) while ensuring an acceptable material quality. This paper presents a methodology to estimate manufacturing time that combines kinematic and thermal criteria for Wire and Arc Additive Manufacturing (WAAM) process. Application is performed for stainless steel 316L. In this first step toward an advanced manufacturing time estimator, only the first layer attached to the building plate is analyzed from a thermal point of view. The thermal analysis is based on an analytical model enabling the evaluation of the preheating temperature (PhT) in a first approach and providing an adequate framework for the evaluation of cooling curves in a second time. The model includes an accurate description of robot kinematics through the consideration of a realistic travel speed variation along the toolpath. It is used to evaluate an indicator that quantifies the thermal influence of a given deposition strategy. The results show the dependency relationship between manufacturing strategy and inherent thermal gradient and its implications on part production time. [ABSTRACT FROM AUTHOR]

This article discusses the effect of machining assistance on the machinability and surface integrity of titanium and nickel-based alloys for turning operations. The presented results are based on a literature review of the principal experimental work published by the French research laboratories within the framework of the Manufacturing 21 group. The work presented focuses on the assistances the most studied by the research group: cryogenic assistance and high-pressure assistance. This paper specifically addresses the experimental approaches used to determine the effect of the assistant on the cutting force, tool wear, chip formation, microstructural changes, and residual stresses generated on the workpiece machined surface. This literature review is completed by new results comparing machining tests on the Ti6Al4V titanium alloy using high pressure and cryogenic assistances. The results show that the assistances increase the tool life, as well as improve the surface integrity of the parts. However, these gains are not identical from one material to another. In particular, titanium alloys and nickel alloys show how a very different gains for a fixed assistance. The conclusions presented highlight current trends and research needs. [ABSTRACT FROM AUTHOR]

Orthogonal cutting on Ti-6Al-4V produces segmented chips which results from localized deformation within the Primary Shear Zone (PSZ). For in situ visualization of the material flow during Ti-6Al-4V chip formation, a new high-speed optical system is proposed. Difficulties arise from the submillimetric size of the cutting zone. Therefore, a dedicated optical system with coaxial illumination is designed allowing for local scale analysis of chip formation. In this paper, the cutting forces were measured highlighting the unsteady nature of Ti-6Al-4V chip segmentation. For kinematic fields measurement, a novel method of Digital Image Correlation (DIC) technique is applied on the recorded images from the cutting zone. It allows for the identification of the localized deformation bands. Then, the level of the cumulative strain fields reached in the PSZ was presented and analyzed. The effect of the rake angle on the strain fields was studied. Using a 0∘ rake angle, the segment chip was found to be more subjected to deformation than in the case using 15∘. Accuracy of the measured strain fields was discussed function of the main source of errors. In addition, the chip morphology and microstructure were investigated with a scanning electron microscopy (SEM). It shows crack opening along the PSZ and high material failure near the tool-chip interface which explains the difficulties of DIC application in the context of kinematic fields measurement during orthogonal cutting. Finally, correlation between the measured strain fields and the mean value of the chip segment width was made. [ABSTRACT FROM AUTHOR]

The article focuses on the analysis of changes in the surface morphology of planer knives modified with four different anti-wear coatings: multilayer, monolithic, monolithic-gradient, and gradient. The coatings described in the article affect the extension of planer tools service life in the range from 153 to 269%. The main objective of the paper was to determine the effect of vacuum-plasma modification of working surfaces of tools intended for machine processing of wooden parts on their geometric structure. The research was carried out on planer knives made of HS6-5–2 high-speed steel and used in industrial conditions. The present work sums up the knowledge resulting from the exploitation tests of modified knives with the features defining the morphology of their working surfaces. The paper comprehensively characterizes the 3D surface roughness parameters, as well as other characteristics such as isotropy and depths histogram. The knife surface modified with a gradient coating (longest life 269%) had a high level of anisotropy. Rose directions with texture directions present that this kind of coating generated structure with 4.23% value of isotropy. The distribution of ordinates was characterized by high clustering and an negative skewness (Ssk = − 0.74). The results described can be used in the design and quality assessment of thin anti-wear coatings, as well as in preparation of substrates for their application. [ABSTRACT FROM AUTHOR]

The contemporary industry has witnessed a significant transformative development with the integration of artificial intelligence (AI) in various industrial systems, resulting in an enhanced automation for heightened productivity and efficiency. However, mastering this level of automation can be challenging for some applications, such as manufacturing inspection, which can be delicate while maintaining a precise cadence for an in-line manufacturing scale. In this paper, a systematic machine vision-based approach for on-machine inspection is proposed in order to automate and improve inspection process towards computer numerical control (CNC) machined parts. The approach incorporates remapping algorithm and image processing operations to accurately extract desired features. Subsequently, these features will undergo dimensional inspection based on their generated point clouds. Tests were applied on a sample part using a complementary metal–oxide–semiconductor (CMOS) camera mounted on the spindle of 5-axis CNC machining center. The paper explores numerous aspects related to different stages of the approach and their impact on the resulting inspected features evaluations. It also highlights significant findings regarding critical factors for conducting well-structured experiments at various stages. Promising results have shown the significance of the presented work regarding industrial automation technology, ultimately improving manufacturing efficiency throughout the production line. [ABSTRACT FROM AUTHOR]

As a kind of interference rivet with compensation at the head, the reduced countersunk head half-crown rivet can achieve long life sealing riveting for airplane types or engine rooms with special requirements for sealing and fatigue performance. In the present study, a quartered three-dimensional finite element model was created to simulate the riveting process. The FE model was validated from the perspective of driven head dimensions and interferences based on the experiment results. The effects of feed displacement of rivet dies, feed speed ratio of rivet dies, pre-feed displacement of upper rivet die and countersunk depth on the forming quality of riveted lap joints were systematically studied. The results showed that the average interference increased with the increase of the feed displacement of rivet dies, while it decreased with the increase of the feed speed ratio of rivet dies and pre-feed displacement of upper rivet die. The countersunk depth of 1.05 mm is the transition depth for the rivet studied in this paper. In addition, the results of combined effect of feed speed ratio of rivet dies and pre-feed displacement of upper rivet die on the forming quality proved that the influence laws of single parameter were no longer suited for the scenario of combined effect of multiple riveting parameters. This paper can provide scientific and normative guidance for the applications of reduced countersunk head half-crown rivet in engineering structure. [ABSTRACT FROM AUTHOR]

This paper comprehensively reviews the process parameters optimization in plastic injection molding (PIM) using the metamodel-based optimization. The PIM is a typical manufacturing technology to produce lightweight and high gloss appearance plastic products. To produce the plastic product, the process parameters such as melt temperature, injection time, packing pressure, packing time, cooling temperature, and cooling time are conventionally adjusted through the trial-and-error method. Computer-aided engineering (CAE) is one of the alternatives in the PIM but the numerical simulation is computationally so expensive that the metamodel-based optimization is widely used to determine the optimal process parameters. First, typical metamodels including the sampling strategy are briefly reviewed. Then, the papers on the process parameters optimization for high product quality such as warpage, shrinkage, and weldline reduction are reviewed. Rapid heat cycle molding (RHCM) that actively controls the mold temperature is a novel PIM technology, but the process parameters optimization in RHCM is rarely discussed in the literature. Then, the RHCM is also reviewed in this paper. Not only the process parameters optimization but also the cooling channel plays an important role for high product quality and high productivity. Due to the recent advancement of metal 3D printer, it is possible to produce conformal cooling channel. It is possible to enhance the product quality and productivity by using the conformal cooling channel. Several papers on the process parameters using the conformal cooling channel are also reviewed. [ABSTRACT FROM AUTHOR]

In laser manufacturing, the cutting parameters, such as laser power, cutting speed, assist gas pressure, and stand off distance, have a great influence on the quality of the machined parts. To ensure the quality of the machined part, the process information (cutting parameters) needs to be manually assigned and adjusted according to the different geometry characters of the part edges, like arc and line segment. The part contours are then used for generating the laser cutting paths, leaving the process information behind. Quickly and accurately transferring the process information to the corresponding cutting paths is not an easy task. In this paper, an algorithm is proposed for this task. The proposed algorithm passes information by the points in the cutting paths. First, all part edges containing process information are offset to generate closed contours. Then, whether the points in the cutting paths are included in the closed contours are judged and marked. Finally, the information as NC codes through the adjacent points in the cutting paths is outputted. To simplify the computation work, a fast approach is also proposed to determine whether the point cloud is contained in a closed contour. The feasibility and computational efficiency of the proposed algorithms are verified by examples, and the actual cutting comparison verifies the superiority of the proposed algorithm by cutting details of machined parts. [ABSTRACT FROM AUTHOR]

This paper proposes a synchronous measurement system of four position-independent geometric errors (PIGEs) and two position-dependent geometric errors (PDGEs) for the rotary axis in five-axis machine tools. The measuring instruments used in this system include a touch-trigger probe and two standard calibration spheres. The main contribution of this paper simultaneously and directly measures four PIGEs and two PDGEs (axial and angular positioning errors) through only one measuring process. It is expected to improve the deficiencies of previous studies measuring PIGEs and PDGEs separately. The geometric errors of the C-axis of a mill-turn machine tool MT-540 were analyzed. The calculation process includes the establishment of the mathematical model of the machine and geometric error equations. The least squares method was used to solve the linear overdetermined system and calculate the values of the geometric errors. Before solving the geometric errors, the accuracy of the calculation process was verified by using the simulated method. The simulation results also confirm the feasibility of this measurement system. Then the data obtained from the experiments were used to calculate the geometric errors of the machine tool. During the experiments, the calibration procedure of the touch-trigger probe was calibrated. After the calibration procedure was completed, the mechanical coordinate values of the two standard calibration balls were measured. The geometric error equations were programmed on a computer, and the data of calibration spheres obtained from the experimental measurements were substituted into the program to calculate the four PIGEs and two PDGEs. [ABSTRACT FROM AUTHOR]

With the development of artificial intelligence, big data, Internet of Things, and other technologies, digital twin has gained great attention and become a current research topic. Using digital twin technology, the digital twin model can be constructed in the cyber space that is fully equivalent to the physical entity. It is always consistent with the physical entity in the operation process, which greatly improves the dynamic perception and prediction ability of the real world. After the development in recent years, digital twin has gradually changed from the initial concept discussion to the study of model framework and implementation method. However, because the research objects in different industries have great differences in their own composition, service conditions, and application scenarios, they have personalized characteristics in modeling strategies and usage methods. Therefore, based on different industries, this paper reviews the current articles on digital twins and distinguishes the focus of digital twin modeling research; subsequently, the relevant supporting techniques and methods are summarized according to their different importance for digital twin modeling. Based on the review in this paper, future researchers can conduct targeted research on digital twin technology in term of the characteristics of the objects in their industry. [ABSTRACT FROM AUTHOR]

In this paper, thin-walled aluminum alloy parts were fabricated using electromagnetic incremental forming with an elastic cushion. The effect of the thickness of the elastic cushion and the discharge voltage on the skin-forming quality is analyzed using numerical simulation. When the discharge voltage is 6 kV, the springback of the sheet decreases with increasing cushion thickness. However, when the cushion thickness increases to 15 mm, the sheet surface produces a 0.78-mm bulge. When, however, a 10-mm-thick cushion is used, the springback of the sheet decreases with increasing discharge voltage. On the other hand, when the discharge voltage is 8 kV, the surface of the plate produces a 1.14-mm bulge, which makes the surface not smooth. Therefore, the optimal process parameters in this paper are a 7-kV discharge voltage and a 10-mm cushion thickness. Moreover, the springback of the sheet metal can be greatly reduced after discharging six times at different positions. Based on the optimum process parameters, which are determined by the numerical simulation, experimental testing is performed. The experimental results are consistent with the simulation. [ABSTRACT FROM AUTHOR]

In this paper, a micro-bump tool is designed to prepare micro-bumps on the rake face of different tools for cutting titanium alloys. The study found that the micro-bump tool can effectively reduce the tool surface temperature (up to 26.83%) and reduce tool wear (up to 25.2%) due to the presence of bumps that change the contact state between the chip and the tool surface. The only downside is that the cutting force during cutting is higher than with ordinary tools. Aiming at this downside, this paper studies the cutting states (20–600 °C) of three conventional tools and corresponding micro-bump tools at different heat-assisted temperatures by using heat-assisted machining technology. The study found that the application of heat-assisted machining technology can effectively reduce the cutting force of the micro-bump tool, while retaining the advantages of the micro-bump tool, which can reduce temperature and reduce wear at different hot working temperatures. [ABSTRACT FROM AUTHOR]

Maintainability, especially for complex products, is a very important general quality characteristic. Physical accessibility is the primary element in maintainability design. Up to now, VR (virtual reality) technology-assisted maintainability evaluation, analysis and design, called virtual maintenance, has become the mainstream and achieved some results. In virtual maintenance, the most widely used accessibility evaluation method is to use virtual human accessible envelope to judge and evaluate accessibility. However, this method can only give two kinds of evaluation results: accessible and inaccessible. Moreover, the envelope lacks sufficient data and theoretical support, so the precision and accuracy of evaluation method need to be improved. In this paper, a parameterized accessibility evaluation method is proposed and the corresponding evaluation models and tool are created. Firstly, to objectively describe the movement of human body, a 6-joint and 5-link D-H (Denavit–Hartenberg) link model is established from the waist to the fingertip of the human body, and the ranges of 10 degrees of freedom and angles related to accessibility are determined according to ergonomics. Then, comfort is introduced to refine the accessibility evaluation, and a multi-level accessibility evaluation system based on comfort is constructed according to RULA (the rapid upper limb assessment). Thirdly, in order to facilitate the application of this method in virtual environment, accessibility envelope models and accessibility evaluation tool are created based on the proposed method. Finally, compared with RULA and the accessible envelope provided by DELMIA, respectively, the results from virtual and real environment of the comparative experiment show that the proposed method and tool are accurate, more precise and more efficient. [ABSTRACT FROM AUTHOR]

The static stiffness of machine tools is one of the key parameters influencing the accuracy of dimensions, shape, and relative positioning of the surfaces of workpieces being machined. This paper presents an analysis of the effect of the stiffness of individual structural components on the resulting stiffness of a prototype vertical lathe with a steel-polymer concrete main frame. This analysis was carried out using a finite element model of the lathe, which was experimentally verified. It was shown that filling the body with polymer concrete significantly (by 30%) increases the static stiffness and damping of the lathe's steel support system. However, the sensitivity analysis carried out in the paper showed that the tool head bearing stiffness has a more significant effect on the static stiffness of the machine tool. [ABSTRACT FROM AUTHOR]

Abrasive water jet peening, which integrates the characteristics of water jet peening and shot peening, is a potential process for surface strengthening of metal materials. In this paper, the peening process of 316L stainless steel by abrasive water jet was studied in this paper. The effects of standoff distance and traverse speed on peening quality and efficiency were analyzed. On this basis, the selection strategy of these two parameters was clarified. The results show that the core zone, transition zone, and minute effect zone were formed at the impact part due to the change of the energy of abrasive water jet. Among them, the peening quality of the core zone is the best. With the increase of standoff distance and traverse speed, the peening quality of the core zone decreased, but the efficiency was greatly improved. In practical application, the standoff distance and traverse speed can be set according to the actual needs. From the perspective of efficiency, on the basis of meeting the needs of peening quality, the standoff distance and traverse speed should be set to a high level. [ABSTRACT FROM AUTHOR]

In this paper, an automatic and quick evaluating method for the micro-hole size and form accuracy with a computer-aided technique was proposed. A special ultrasonic microforming method, that is, micro-ultrasonic thin-sheet-metal forming using molten plastic as flexible punch (short as Micro-USF), was used to punch out micro-holes with diameters of 500, 600, and 700 μm on a copper sheet with a thickness of 30 μm. Using the evaluation method proposed in this paper, the forming accuracy of micro-holes was discussed. The experimental results showed that the ratios of the maximum size error and the maximum roundness error of micro-holes to the corresponding punching die diameter were 1.40 and 1.47%, respectively. The ratios of the maximum size error range and the maximum roundness error range of micro-holes to the corresponding punching die diameter were 0.70 and 0.72%, respectively. This indicated that the accuracy and precision in the Micro-USF method were high for punching micro-holes. Moreover, it was found that there is no significant direct correlation between micro-holes sample errors and these forming parameters when the forming parameters such as ultrasonic power, ultrasonic time, and cylinder pressure were varied, which indicated that the sample errors were random to some extent. [ABSTRACT FROM AUTHOR]

This paper proposes a new flexible and microscale roll gap control technology to obtain a stronger strip flatness control ability. According to the principle of microscale roll gap control technology, an electromagnetic control rolling mill with the function of roll profile control and large diameter ratio rolling is designed and built. To analyze the flatness control ability, a comprehensive finite element model (FEM) is established, and an indentation experiment and a rolling experiment are carried out. The simulation results show that under different rolling forces and tensions, the average quadratic crown control ability is more than 40 μm, and the average quartic crown control ability is more than − 3 μm. The control ability increment of the quadratic crown is greater than that of the quartic crown. In the indentation experiment, a stable roll profile can be achieved by PID control after reaching the target roll profile. Increasing the regulation amount can change the strip crown from positive to negative. Even under high rolling force conditions, microscale roll gap control technology can also realize a strip crown adjustment of 19.5 to 0.5 μm. Moreover, this technology can adjust the strip shape from edge waves to non-waves and middle waves in the rolling experiment. In this paper, the feasibility of using this technology to adjust the roll gap shape has been verified, and we demonstrate that the roll gap control goal of uniform transverse size distribution can be achieved. [ABSTRACT FROM AUTHOR]

A grain-arranged grinding wheel refers to a grinding wheel where the position of abrasive particles on the wheel can be customized. In this paper, the processing quality of the grain-arranged grinding wheel in different grain arrangements, including rectangle, rhomboid, and oblique rectangle arrangement, respectively, is compared with that of conventional grinding wheel in the grinding of single-crystal silicon. Comparisons have also been made between arranged wheel in oblique rectangle arrangement and conventional wheel in terms of 2D- and 3D-machined surface morphology, surface roughness, and grinding force. By considering the effects of the material removal process, abrasive grain interactions, and grain arrangement parameters, a grinding force model is built for the grain-arranged grinding wheel. Through processing experiments with different grinding wheels, it is found that the grain arrangement has a great influence on the machined surface quality. Rational and orderly grain arrangement can improve the machined surface quality and machining stability, but the machined surface quality of a grain-arranged wheel is not always better than that of a conventional wheel. Specifically, the machined surface quality of arranged wheels in rectangle arrangement is always the worst, but the difference of machined surface quality of the other three kinds of grinding wheels is not significant at low feeding velocity. With the increase of feeding velocity, the machined surface quality of arranged wheel in oblique rectangle and rhomboid grain arrangement will gradually be better than that of the conventional wheel. In respect of grinding force, it is found that arranged wheel in oblique rectangle arrangement owns a smaller average force and a more stable momentary force than that of the conventional grinding wheel. For the grinding force model built in this paper, its effectiveness and accuracy were finally verified by experiments. [ABSTRACT FROM AUTHOR]

This paper proposed a kinematic model and its calibration scheme to further improve an industrial robots absolute positioning accuracy over the entire workspace. To demonstrate the proposed model and its effectiveness in simplified kinematics, this paper only targets a SCARA (Selective Compliance Assembly Robot Arm)-type robot. The proposed model includes not only link length errors and rotary axis angular offsets, widely known as the Denavit-Hartenberg (D-H) parameters, but also the "error map" of the angular positioning deviation of each rotary axis, modelled as a function of command angular position, and the rotation direction to model the influence of backlash. The angular positioning deviation of each rotary axis is identified by measuring the robots end-effector position by a laser tracker with indexing each rotary axis at prescribed angular positions. To verify the validity of the identified model, the effectiveness of the compensation based on it is experimentally investigated. By the compensation, the robot's average absolute position error was reduced by 33% to 0.034mm. Furthermore, this paper experimentally demonstrates that the proposed model can be extended to the radial error motion, axis-to-axis cross talk, and the three-dimensional positioning with orientation errors of axis average lines. [ABSTRACT FROM AUTHOR]

Integral blisk blades are typical complex curved structures with small thickness, low stiffness, and complex boundaries. Due to the high material removal rate during the machining process, they are prone to force-induced deformation, resulting in significant machining errors. This seriously contradicts the requirements for high design accuracy and surface accuracy in the aerospace industry. Therefore, accurately predicting the distribution pattern of deformation caused by dynamic milling forces during the machining process and proposing reasonable error compensation strategies are urgent issues to be solved in the manufacturing of integral blisk blade. Firstly, this paper establishes a prediction model for the deformation distribution during the milling process of the integral blisk blade. Secondly, based on the finite element deformation prediction model of blades, the selection of blade milling processing methods and parameters was completed with the goal of minimizing machining deformation. Finally, a reverse reconstruction geometric modeling compensation strategy is proposed, and the tool path program containing the deformation error compensation amount is regenerated. The prediction model and compensation strategy proposed in this paper were validated through milling experiments and profile accuracy measurement experiments on a certain aeroengine integral blisk blade. The results showed that the prediction model has high reliability, with an average error of 7.96%; the new compensation strategy can reduce the tool-yielding error to within the tolerance range. This study will provide technical support for improving the machining accuracy and efficiency of integral blisk blade. [ABSTRACT FROM AUTHOR]

This paper adopts electrochemical machining (ECM) to machine spiral-shaped deep holes, which are difficult to machine by conventional machining methods. Firstly, a cathode structure with two working teeth with increasing spiral end face dimensions was designed. The interstitial flow field and interstitial bubble field were modelled, and simulations were carried out using COMSOL simulation software to realise the optimisation of the cathode working teeth structure. The results show that the cathode structure with four incremental baths provides good uniformity of gap electrolyte flow, and the flow rate is significantly increased, reaching over 6 m/s. The concentration of bubbles in the interstitial electrolyte is significantly reduced, with a reduced rate of 47% and a smaller bubble distribution area. Processing accuracy and surface quality are effectively improved. Secondly, ECM experiments were carried out. The experimental results were analysed using the response surface method for multi-objective optimisation. The optimised process parameters were obtained as follows: inlet pressure 0.7 MPa, machining voltage 10 V and feed rate 0.9 mm/min. Finally, a qualified sample was machined using the optimised process parameters. The dimensional deviation is 0.28 mm and the roughness is 1.398 μm, which meets the product requirements. This simulation and optimisation method effectively shortens the cathode development cycle and reduces production costs. [ABSTRACT FROM AUTHOR]

Compared with traditional CNC machines, robot milling has the advantages of low cost, high flexibility, and strong adaptability, providing a new solution for complex surface machining. However, robot machining trajectory planning in the real world is time-consuming and has safety risks. At the same time, how to achieve 3D visualization monitoring in the milling process effectively is also a challenging problem. Digital twin technology, with its characteristics of multi-dimension, high-fidelity, virtual-real fusion, and real-time interaction, provides an effective way to solve these problems. For this purpose, the paper designs and implements a robot milling motion simulation and visualization monitoring system based on the digital twin system framework. The system uses the Unity3D platform to construct the robot's digital twin body, designs a material removal algorithm based on mesh deformation, and establishes a milling motion simulation model. Through virtual-real mapping technology, the system establishes a bidirectional communication between virtual and physical entities and achieves the result mapping of the robot milling motion simulation and the visualization monitoring of the milling process. Finally, the motion simulation and real-time visualization monitoring of the milling process are tested, verifying the effectiveness and timeliness of the system. [ABSTRACT FROM AUTHOR]

Electrochemical machining (ECM) is widely used as a special process in the manufacturing of parts. The introduction of a magnetic field can improve manufacturing quality and increase the electrochemical reaction rate. Magnetic fields have a non-negligible influence on processes such as mass transfer, polarization, limiting current density, electrocrystallization, and anodic dissolution in electrochemical reactions. This paper provides a comprehensive review of magnetoelectrochemistry (MEC) techniques and the effect of magnetic fields on ECM. Starting from the MEC effects caused by magnetic fields acting on ECM, as well as Maxwell stress effects and magnetocaloric effect, which have not yet been studied in the field of ECM, this paper summarizes the effect of magnetic field on electrochemical reaction rate, flow field, physicochemical properties of electrolyte, and material formation in ECM, reviews existing magnetic field-assisted ECM technologies, and proposes future applications of magnetic fields in electrochemical additive manufacturing (ECAM) technologies. Finally, the paper provides a summary and outlook to serve as a reference for MEC processing. [ABSTRACT FROM AUTHOR]

The paper deals with the calculation of interstand tensions in continuous rolling mills.In the rolling mill industry, continuous measurement and data collection of roll forces, roll torques, temperatures and roll velocities is possible. However, the important process parameter of interstand tensions is not directly measurable and no direct calculation of the interstand tensions is possible. The interstand tensions couple the effects of subsequent roll gaps and should therefore by known for a holistic recalculation of the process. It is straightforward to calculate the effects of the tensions on roll forces, torques and the stock velocity. The inverse problem of calculating the acting interstand tensions including their effects from the process parameters is of greater interest but also of a higher complexity, because the interactions between all the stands in the rolling mill must be regarded. The present paper aims at filling this research gap by presenting a mathematical model to solve the inverse problem by a linearization of the tensions influences in the rolling mill. The present model does not require measured roll forces or torques to find the interstand tensions, only the rotational velocities of the rolls and the rolling parameters (material, temperature, pass schedule or pass design) must be known. Tension-dependent spread is considered by an empirical sub-model. Results are shown for the tension distributions in strip and rod mills. The results indicate that the present friction conditions and the entry size of the rolled stock have a high impact on the tension distributions. [ABSTRACT FROM AUTHOR]

Microfluidics is a crucial technology in biological and medical fields, and its traditional fabrication methods include soft photolithography poly(dimethyl siloxane) (PDMS) technology and polymethyl methacrylate (PMMA) injection moulding technology. However, these techniques face challenges in manual alignment and bonding issues when they are used to manufacture microfluidic chips with complex flow channels. To overcome these limitations, digital light processor (DLP) 3D printing technology has been proposed as a promising alternative. However, this method is prone to problems such as channel blockage or shape distortion caused by the optical proximity effect or curing light transmission during the manufacture of microfluidic chips with small-diameter channels. This paper introduces a method to enhance the manufacturing technology by controlling the local greyscale of the projection image during DLP 3D printing. This allows for modulation of the curing light intensity, thus reducing the optical proximity effect and the impact of transmitted light on extra areas. The methodology can be employed in the production of microfluidic devices with circular and square apertures in the microchannels, utilizing commercially accessible general-purpose resins that are readily available in the market. The printed microfluidic devices show improved quality, with a channel size that closely matches the preset size, in contrast to significant channel blockage in devices printed without greyscale optimization. This method provides a new approach for enhancing the quality of low-cost microfluidic chip production and improves the print quality based on the resolution of the printer and resin used. [ABSTRACT FROM AUTHOR]

In this paper, a new laser linkage processing method based on trajectory distribution of galvanometer and mechanical servo system is proposed to achieve large-range high-feedrate laser processing. The proposed method can effectively improve the processing range, accuracy, and efficiency. Firstly, according to the processing trajectory characteristics of the galvanometer and mechanical servo system, a trajectory distribution filter algorithm is designed to reasonably distribute the interpolated trajectory to the equipment. Then, two linkage processing methods are designed based on off-line trajectory and real-time trajectory distribution. Moreover, an experimental platform consisting of the laser, galvanometer, and mechanical servo system is built, and experiments are performed on experimental equipment to verify these methods. Finally, the experimental data is collected at different processing feedrates, and the processing errors of two linkage processing methods and mechanical servo system processing are calculated and compared. The processing accuracy and effect of linkage processing are effectively improved. In addition, the processing effect of real-time trajectory distribution is also improved compared to the off-line trajectory distribution, which is simpler and easier to implement. These methods have been successfully applied to the large-scale high-feedrate laser processing equipment in the laboratory. [ABSTRACT FROM AUTHOR]

The research carried out by the authors of this paper is focused on the technological process of Inconel 625 welding with the MAG–CMT (Metal Active Gas-Cold Metal Transfer) method. Inconel 625 was welded to the substrate material, which was 16Mo3 steel. Both materials are used to produce the so-called bimetallic tubes, which in practice serve as a part of the equipment intended for waste incineration. For this reason, the bimetallic tubes must withstand extreme conditions during their operation. Therefore, bimetal pipes are highly stressed composite components that must resist corrosion in a chemically aggressive environment. For this reason, an extensive material and technological analysis of the production of pipe bends with a supercritical bend of 0.7D from bimetal pipes with Inconel 625 cladding was performed. In the welding process, the authors investigated the possibilities of the CMT method with and without using the oscillating movement of the welding head. The most important factor in deciding which method would be appropriate was to measure the amount of iron on the surface of the coating layer. The authors' paper builds on the authors' previous research in this area, which was mainly focused on research on the critical bending of bimetallic tubes. [ABSTRACT FROM AUTHOR]

Doubly curved high strength steel sheets in small batch have been widely applied in shipbuilding, aerospace, automobile, and other manufacturing fields to meet the lightweight market demand. To achieve the doubly curved high strength steel sheets with smaller forming force, the multi-point incremental bending process was proposed. In addition, to deform the high strength steel Q345B sheets efficiently and accurately, the tools' loading path strategy under the minimum strain energy field (that is, along the principal curvature direction) with considering the springback height was proposed. In this paper, the single-point bending-springback characterization at different bending positions and that with different incremental bending depths were analyzed based on experiments and numerical simulations to finally determine the whole springback height distribution for the entire high strength steel sheet. Then, the high strength steel sheet with target doubly curved surface was deformed experimentally by the multi-point incremental bending experiments based on two kinds of tools' loading paths according to whether to consider the springback height of the high strength steel sheet. The maximum loading forces and the absolute shape error were compared and analyzed. Results validated the reliability of the multi-point incremental bending experiment along the principal curvature direction with considering the springback height and the paper also put forward the following up to be improved for the flexible incremental bending process in the future. [ABSTRACT FROM AUTHOR]

Superalloys are widely used in aerospace and energy fields by virtue of superior physical properties, especially in high-temperature environments. However, superalloys have poor machinability and are typical difficult-to-machine materials. Robotic belt grinding is an effective and popular method for finish machining superalloys, offering significant advantages such as high material removal capacity, low heat input, and fewer workpiece damages. Moreover, robots can be well integrated with multi sensors, such as infrared radiation cameras, force sensors, microphones, and high-speed cameras. These sensors help to realize real-time monitoring of grinding processes, thus benefiting the grinding quality control. Despite many developments in recent decades, there is a lack of comprehensive review of robotic belt grinding of superalloys, particularly advanced techniques and methods to achieve precision profile finishing and desired properties. Therefore, after introducing a typical intelligent robotic grinding system, this paper reviews five important aspects that need further research for robotic belt grinding of superalloys: typical tools and grinding parameters selection, surface integrity analysis and control, tool condition motoring, material removal, and finishing control, as well as the force distribution and thermal analysis. The typical applications, potentials, and limitations are also introduced. As an emerging technology, artificial intelligence (AI) is imperative to realize intelligent robotic belt grinding. Hence, this paper pays more attention on AI-based models of grinding processes. [ABSTRACT FROM AUTHOR]

This paper deals with a method for performance calculation of shuttle-based storage and retrieval system (SBS/RS) with tier-captive aisle-changing shuttles and different storage strategies. The shuttles are assigned to a certain number of aisles in this system. The invented approach takes place in the design process of SBS/RS. A continuous time open-queueing system with a limited capacity approach is applied. A discrete spatial value approach determines the inter-arrival times and service times. A probability-based model mentions the aisle changing. This approach is validated by comparison to a Monte-Carlo simulation. A European material handling provider gave the data used in this comparison to validate this approach. Finally, an example of the usage in the design process of SBS/RS of the invented analytical approach is depicted. The result is an increase in throughput with an increasing number of aisles per shuttle. Likewise, the storage strategy greatly influences the throughput between random storage and retrieval and same aisle storage and retrieval. [ABSTRACT FROM AUTHOR]

This paper proposes to qualify the minimal quality deviation that can be detected by a near-infrared camera during aluminum wire arc additive manufacturing. First, a review of the literature is done to highlight the interest in monitoring the melt pool in industrial condition for thermal management during manufacturing. It points out the relevance of the use of a near-infrared camera for steels, but it has to be demonstrated for aluminum alloys. Indeed, the melt pool of the aluminum is significantly dimmer and less distinct than the melt pool of the steels. An experimental design is proposed to qualify the minimal quality deviation that can be detected on a thin wall. The chosen default to correlate with the thermal deviation is the width of the wall. A method is proposed to extract a thermal metric from the camera image and to analyze its sensitivity to a width deviation of the wall. The paper shows the correlation between the width of the wall and the thermal metric for different heat conditions. Moreover, the thermal metric is sensitive to width deviation either on the wall scale or on the bead scale. It indicates the relevance of a near-infrared camera to detect heat accumulation-induced width deviation during wire arc additive manufacturing of aluminum alloy. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to solve a series of problems, such as the difficulty in accurately controlling the specific surfaces, and the interference between the laser beam and the part, when the laser is used to clean mechanical parts with complex surfaces by using robots. Firstly, a region segmentation algorithm of the stereo lithography (STL) model was designed, and the feature surfaces of the model were obtained by using the dihedral angle as the criterion. Then the path points which could easily cause interference between the laser beam and the part to be cleaned were detected by the method of ray intersection, and the pose of the robot was modified according to the normal vectors of two non-interference points that were adjacent to the continuous interference points respectively. Finally, the proposed method was validated by scanning path visualization and robot laser cleaning process experiments. The generated path in the unit of feature surface according to the variation components of normal vectors proved the effectiveness of the STL model region segmentation algorithm based on dihedral angle division criteria; the change of the normal vectors of the path points on the current feature surface was continuous and smooth, which meant that the path points did not cause sudden change of the robot pose after the pose correction. The robot cleaned the specific surfaces of the test workpiece safely and effectively in the actual laser cleaning experiments, and the effective cleaning area reached 96.87%, 99.56%, 94.53% and 91.62% of the target cleaning area, which further proved the effectiveness of this study. The method is also useful for the path planning of robots in other processing fields. [ABSTRACT FROM AUTHOR]

In this paper, for the first time, the role of manufacturing parameters of fused deposition modeling (FDM) on the shape memory effect (SME) is investigated by design of experiments. PLA-TPU blend with a weight composition of 30:70% is processed by melt mixing and then extruded into 1.75 mm filaments for 3D printing via FDM. SEM images reveal that TPU droplets are distributed in the PLA matrix, and the immiscible matrix-droplet morphology is evident. Box-Behnken design (BBD), as an experimental design of the response surface method (RSM), is implemented to fit the model between variables and responses. The shell, infill density, and nozzle temperature are selected as variables, and their effects on loading stress, recovery stress, shape fixity, and shape recovery ratio are studied in detail. An analysis of variance (ANOVA) is applied to estimate the importance of each printing parameter on the output response and assess the fitness of the presented model. The ANOVA results reveal the high accuracy of the model and the importance of the parameters. Infill density and nozzle temperature had the greatest and least roles on shape memory properties, respectively. Also, the values of shape fixity and shape recovery were obtained in the ranges of 58–100% and 53–91%, respectively. Despite many researches on 4D printing of PLA, low ductility at room temperature and high stress relaxation rate are its weakness, which are covered by adding TPU in this research. Due to the lack of similar outcomes in the specialized literature, this paper is likely to fill the gap in the state-of-the-art problem and supply pertinent data that are instrumental for FDM 3D printing of functional shape memory polymers with less material consumption. [ABSTRACT FROM AUTHOR]

In CNC milling, the feed rate scheduling is a frequently used method to increase machining quality and efficiency. Among the benefits of feed rate scheduling, this paper focuses on controlling the tool load and optimizing the machining time. Although the advantages of feed rate scheduling are undeniable, some areas remain still to be addressed. In order to control the tool load, geometric methods are often used, which are based on keeping a specific parameter, such as chip thickness or material removal rate (MRR) constant. However, a high level of tool load control can only be provided if cutting force models or experimental-based techniques are used. Besides traditional methods, this paper presents an artificial neural network (ANN)-based feed rate scheduling method to keep the tool load constant, using data gained by preliminary cutting experiments. A case study demonstrates that a significantly higher level of tool load control can be achieved with this method as compared to the geometric models. Besides controlling the tool load, the present feed rate scheduling method also addresses the consideration of acceleration limits which is of great importance for practical uses. The application of feed rate scheduling in trochoidal milling is also discussed in detail in this paper. This area has not received enough attention, as due to the limited fluctuation of cutter engagement, the tool load was considered as well-controlled. However, experiments have shown that in the case of trochoidal milling, the introduction of feed rate scheduling can still further increase the machining efficiency. Using the developed ANN-based feed rate scheduling method, significant progress could be made as compared to conventional technologies in controlling the cutting force and optimizing the machining time. In the present case study, a reduction of 50% in machining time was achievable by adjusting the feed rate without increasing the peak value of cutting force. [ABSTRACT FROM AUTHOR]

In order to investigate the influence of reinforcing particles on the machining process and the machined surface, a single-particle turning simulation of particle-reinforced titanium matrix composites (PTMCs) is carried out in this paper. The hard reinforcing phase in the particle-reinforced titanium matrix composites was simplified into elliptical particles, and the machining process and surface under various tilt angles were investigated. The effect of TiC particles with different inclination angles on the formation of pits on the machined surface was investigated and a comparative test was conducted to demonstrate the mechanism of surface crater formation. The results show that the surface quality of the processing is strongly influenced by the inclination angle of the reinforcing particles. When the tool cutting path is located in the center of the elliptical particle, the main axis of the elliptical particle is closer to the X-axis, and the particle fragmentation is more serious and the machined surface quality is worse. As the spindle of the elliptical particle gets closer to the Y-axis, the machined surface quality improves significantly. The breakage mechanism of hard TiC particles during PTMCs was analyzed. The interaction mechanism between the actual breaking process and the variation of cutting force was revealed. When the peak value of cutting force is higher, the state of particle breakage in the substrate becomes more severe. The result of this work has important implications for the subsequent suppression of surface defects and improvement of the machined surface quality. [ABSTRACT FROM AUTHOR]

Multi-stage hot forging is widely used to produce complex forged products in inFdustry. Flash after the forging should always be minimized for the material saving, and it is important to determine the preform shape minimizing the flash. The process parameters in multi-stage hot forging such as the billet temperature and the stroke have also an influence on the product quality as well as the flash, but they are still determined by a trial-and-error method. In this paper, multi-objective design optimization in three-dimensional multi-stage hot forging is numerically performed so as to minimize both the flash and the distribution of equivalent strain. The preform shape and the process parameters such as the billet temperature, the die temperature and the stroke are optimized. The three-dimensional numerical simulation is computationally so expensive that sequential approximate optimization that response surface is repeatedly constructed and optimized is adopted to identify the pareto-frontier between the flash and the distribution of equivalent strain. It is found from the numerical result that 60% reduction of flash can be achieved, compared to the conventional preform shape. In addition, the total forging energy considering the multi-stage hot forging is reduced. It is confirmed through the numerical result that the proposed approach is valid to determine the optimal preform shape and process parameters in multi-stage hot forging. [ABSTRACT FROM AUTHOR]

This study concentrates on comparing effects of conventional and laser-assisted machining (LAM) of laser-borided Monel 400 alloy. For this purpose, the shaft made from Monel 400 was covered with 200-µm thick boron layer and surface melted using diode laser. For determining the influence of laser beam scanning velocity on final microstructure, microhardness, and depth of melting, four laser beam scanning velocities were set: 5, 6, 8. and 10 m/min. Obtained microstructures are typical for laser-melted metal and are composed of fine crystals. Microhardness increased significantly due to enriching Monel 400 with boron and the level of this increase depends on the laser beam scanning velocity carried out for the process. During both conventional and laser-assisted turning, cutting forces were measured for comparison. Other compared parameters after carrying out these processes were obtained surface roughness and tool life. It was found that it is possible to form laser-borided surface of Monel 400 alloy by machining and using additional laser-assist has a positive impact on the efficiency of the process. Laser-assisted machining allows to lower cutting forces during machining and this leads to extended tool life. On the other hand, this method provides lower values of roughness parameters on the machined surface due to the effect of softening the surface during the process. The paper is the first description of effects obtained by laser-assisted machining of laser-borided surface. [ABSTRACT FROM AUTHOR]

This paper focuses on identifying the convection heat transfer coefficients of the friction stir welding (FSW) temperature field from the temperature measuring data. Firstly, the numerical model of the FSW temperature field is constructed by utilizing the Lagrangian formulation. Then a novel inversion method combined with the surrogate model is proposed. The surrogate model based on proper orthogonal decomposition and radial basis function (RBF) is applied to approximate the input-output relationship of the numerical model. To improve the calculation efficiency and accuracy of the inversion method, an iterative updating method of the surrogate model combined with parallel computing technology is adopted. Subsequently, the effect of the type of RBF and the measurement position of the thermocouple on the calculation accuracy of the inversion analysis method are analyzed. The conclusions indicate that all the RBFs used in this paper are suitable for constructing the surrogate model of the temperature field. With the thermocouple measuring point close to the weld center, the maximum RMSE calculated by the numerical model decreases from 10.8 °C to 7.0 °C, but the maximum relative error of the peak temperature changes slightly, about 7.5%. The results illustrate that the identified convection heat transfer coefficients allow predictions on the temperature field of FSW which are consistent with the experimental data. [ABSTRACT FROM AUTHOR]

Aerospace, marine energy, and other high-end equipment have a higher and higher demand for performance indicators. The realization of high-performance manufacturing of equipment is particularly critical, and the assembly is the key link. The continuous expansion of application requirements and the continuous improvement of service performance have resulted in increased difficulty and complexity of assembly. Currently, it is a challenge to effectively realize the initial assembly performance of equipment and its long-term stability. The traditional way of assembly is driven by experience and geometric tolerances have certain randomness and uncertainty. These issues result in low assembly efficiency and accuracy and low one-time pass rate. In service, the service performance is inconsistent with the initial assembly performance, resulting in abnormal vibration or failure of equipment. Thus, performance-oriented digital twin (DT) assembly can overcome the shortcomings of traditional assembly under the high assembly performance (HAP) requirements of high-end equipment. The DT can potentially realize the HAP of high-end equipment using real-time mapping and control of physical entities in virtual space through virtual–real interaction, data fusion, iterative optimization, and other means. However, the performance-oriented DT assembly technology lacks systematic research. Thus, this paper expounds on the connotation of performance-oriented DT assembly technology based on the research status of high-end equipment assembly technology. This article presents a technical framework for performance-oriented DT assembly and discusses the realization approach and key technologies of performance-oriented DT assembly. Finally, its research direction and suggestions are given. The research will reveal the urgent engineering problems of performance-driven active and accurate assembly of high-end equipment and provide a reference for improving assembly performance, consistency, and efficiency. [ABSTRACT FROM AUTHOR]

Ti6Al4V alloy is one of the typical difficult-to-machine materials and often results in rapid tool wear, leading to poor machining quality in aircraft assembling. Compared to conventional helical milling, the ultrasonic assistant helical milling (UAHM) process has indicated its superior performance; however, it is still a great challenge to improve the hole surface quality and accuracy. In addition, few studies have been conducted on the effect of different variables and cooling strategies on the hole-making performance in longitudinal-torsional ultrasonic assisted helical milling (LT-UAHM). This paper, for the first time, reports effects of machining variables on geometric precision and surface roughness in LT-UAHM of Ti6Al4V. In addition, the lubrication/cooling mechanism on the simultaneous application of LT-UAHM and MQL is theoretically analyzed. The design approach of Taguchi experiment was employed to study how major variables such as the cutting speed, tangential feed, axial feed, and the workpiece hardness influence the dimensional and geometrical tolerances and surface roughness. This paper also discussed the effect of three cooling strategies, i.e., dry condition, air coolant, and minimum quantity lubrication (MQL) in LT-UAHM. Theoretical analysis demonstrated that the MQL coolant can be nebulized into hyper-fine droplets owing to the resonant cavitation phenomenon. Combined with the penetrating action caused by the separate-cutting principles of LT-UAHM, the cooling and lubrication performance of MQL was further enhanced. As a result, LT-UAHM with MQL had the most positive effect on circularity, cylindricity, nominal diameter, and surface roughness, contributing to 34%, 32%, 39%, and 40%, respectively. The second important machining factor was the cutting speed, contributing to 31%, 29%, 36%, and 22%, respectively. The tangential feed and workpiece hardness have the negative effect on geometrical accuracy, respectively. [ABSTRACT FROM AUTHOR]

Thin-walled parts (TWPs) are widely used in aerospace, and their service performance is significantly affected by the machining accuracy. Multi-pass machining is used to machine the poor stiffness TWPs. However, it is difficult to accurately predict the final machining accuracy due to surface topography error propagation and accumulation in multi-pass machining. Therefore, this paper proposes a multi-pass machining accuracy prediction method for TWPs based on dynamic factors (cutting force and stiffness). First, a flexible cutting force prediction model, which considers the axial errors determined by the initial surface topography and part deflection, is proposed. Second, a position-pass-dependent stiffness (PPDS) model is established considering the position dependence of stiffness and multi-pass machining material removal. Finally, combining the two models above, a multi-pass machining accuracy prediction method based on a genetic algorithm–back propagation (GA-BP) neural network is proposed. Experiments under various conditions are carried out to validate the proposed method. The machining accuracy (flatness as an example) is as high as 90.8% using the method in this paper, while it is only 73.9% when the accumulative error is neglected. The proposed method can significantly improve the performance of machining accuracy prediction by revealing the error propagation mechanism and the effect of dynamic factors between multi-pass machining. Furthermore, this also provides a theoretical basis for process parameter optimization and machining accuracy improvement in TWP machining. [ABSTRACT FROM AUTHOR]

This paper presents an innovative grasping system for pick-and-place applications, capable of handling a wide range of objects with varying characteristics, including size, shape, weight, rigidity, and fragility. The system uses a four-finger design to incorporate multiple grasping modes, including inner gripping, outer gripping, suction, and pinch-gripping. The paper details the development of a soft actuator system that drives a Watt's Type I link chain for mechanical compliance and passive safety. Additionally, an end-to-end grasping policymaker using depth vision is proposed to determine the optimal grasping mode and finger trajectory. Results from experiments demonstrate the system's versatility and state-of-the-art performance. [ABSTRACT FROM AUTHOR]

In order to realize real-time and precise monitoring of the tool wear in the milling process, this paper presents a tool wear predictive model based on the stacked multilayer denoising autoencoders (SMDAE) technique, the particle swarm optimization with an adaptive learning strategy (PSO-ALS), and the least squares support vector machine (LSSVM). Cutting force and vibration information are adopted as the monitoring signals. Three steps make up the unique feature extraction and fusion method: multi-domain features extraction, principal component analysis (PCA)-based dimension reduction, and SMDAE-based dimension increment. As a novel feature representation learning approach, the SMDAE technique is utilized to fuse the PCA-based fusion features to enrich the effective information by increasing the dimension, thus helping polish up the predictive performance of the proposed model. PSO-ALS is used to obtain the optimal parameters for LSSVM, simplifying the problem and increasing the population diversity. Twelve sets of milling experiments are conducted to demonstrate the reliable performance of the proposed model. The experimental results show that the presented model is superior to models such as PSO-LSSVM in predictive performance, and the SMDAE technique effectively improves the prediction accuracy of the established model. The findings of this paper offer theoretical guidelines for monitoring milling tool wear in real industrial situations. [ABSTRACT FROM AUTHOR]