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The strips with good flatness after finish rolling will have flatness defects such as edge wave after run-out table cooling. These defects are caused by the residual stress due to inhomogeneous thermal and microstructural behaviors during the cooling stage. The traditional residual stress control methods rely too much on experience, resulting in poor control effect and poor universality. Therefore, this study proposed two residual stress control methods based on model calculation: water flow central crown and center wave compensation control. The former is mainly based on controlling the uniformity of strip transverse temperature and microstructure. The latter is mainly controlled by mutual compensation of internal stresses. In this paper, the mathematical models of water flow central crown cooling and critical center wave compensation stress were established, respectively. Meanwhile, a post-buckling model of hot-rolled strip was established to calculate the aim flatness value at exit of finishing mill under critical compensation stress. Furthermore, a fully coupled finite element model based on temperature, phase transitions, and stress was developed and it was verified using experimental data. Finally, the above two residual stress control methods were realized in the finite element model. The results showed that the two methods can reduce the residual stress and improve the flatness, and the application of center wave compensation control is more effective. [ABSTRACT FROM AUTHOR]

Nodular cast iron is widely used to manufacture various important mechanical components due to the comprehensive mechanical properties and relatively low cost. However, the machining efficiency and surface quality of nodular cast iron are difficult to be guaranteed because of the unstable cutting processing and severe tool wear. In this study, the effect of cutting parameters on the cutting performance of nodular cast iron in large size plane ultra-fine-pitched milling was systematically investigated. The dynamic milling force model showed that the milling force of multiple cutting edges was superimposed by the milling force of each cutting edge. When the number of cutting edges varied from 3 to 12, the cutting force increased linearly, while the average cutting force per tooth was almost the same and the cutting process became more stable. The cutting force also increased as the increase of cutting parameters, which was attributed to the strain-hardening effect. The roughness of machined surface decreased by ~ 39.7% with the increase of number of cutting edges from 3 to 12. The increase of feed rate per tooth could reduce the tensile residual stress on the machined surface. The burr on chip edges decreased, and the degree of chip deformation increased with the increase of the number of cutting edges. The tool failure mode was the adhesive wear of the rake face. With the increase of the number of cutting edges in the ultra-fine-pitched milling, the cutting efficiency and tool life could be significantly improved. [ABSTRACT FROM AUTHOR]

This paper presents a study of the relationship between cutting force and tool crater wear of solid carbide tool during milling Ti6Al4V. The cutting force model in milling considering tool crater wear is discussed, which shows that for given the cutting conditions, tool geometries, and workpiece material, cutting force under the tool crater wear effect could be predicted easily and conveniently. The tool wear condition in milling Ti6Al4V is obtained by finite element simulation method. In addition, the experimental work of end milling Ti6Al4V with solid carbide tool is developed. Comparisons among experiment results, mathematical model results, and finite element simulation model results, including cutting force and tool wear, are discussed. The results show that the proposed mathematical model could predict cutting force under the tool crater wear effect with higher accuracy. [ABSTRACT FROM AUTHOR]

Tool wear is accelerated with the friction in the tool–workpiece contact during dry cutting. Tool changing early or late will affect the quality of tool and workpiece. An online and machine system vision-based is built to monitor tool condition in real time. MATLAB is used to compile the self-matching algorithm, which considers the features of interested targets on the flank face. Furthermore, a corresponding GUI is designed and encapsulated for both the bottom and flank edges. It is shown that the absolute value of the error on the maximum wear width is not more than 0.007 mm for the bottom edge. For the flank edge, the absolute value of the error is not more than 0.030 mm owing to the local highlighting interference. It is proved that the system can guarantee the quality of tool and workpiece and avoid unnecessary waste significantly. This platform can enhance the utilization of the tool in dry cutting. [ABSTRACT FROM AUTHOR]

The tandem cold-rolling process is a multivariable, nonlinear, and strongly coupled complex control procedure, in which the key technologies of automatic gauge control (AGC) and automatic tension control (ATC) are extremely comprehensive, and high precision is required. This paper analyzes the rolling characteristics of tandem cold-rolling process and proposes an innovative multivariable optimization strategy based on inverse linear quadratic (ILQ) optimal control theory for thickness and tension control. First, a new state space model of the tandem cold-rolling process was introduced and verified based on the basic equations of rolling technology and field data. Then, meaningful influence rules on the complex rolling process were obtained by analyzing rolling characteristics. For the complex rolling process, a novel ILQ control strategy was introduced into the thickness and tension control system. As a result, by a series of experiments, the effect of disturbance on the thickness and tension was attenuated to an arbitrary degree of accuracy through the proposed control strategy. Simulation results showed the excellent control performance of the proposed ILQ control strategy compared with the conventional proportion and integration (PI) control strategy. [ABSTRACT FROM AUTHOR]

To inspect the tool wear condition in the process of numerical control (NC) machining for difficult-to-cut material, an online inspection system for tool wear is developed based on machine vision. With the help of MATLAB software, a self-matching algorithm is proposed according to the characteristics of tool wear images. The corresponding user-friendly graphical user interface (GUI) of the algorithm is developed. The bottom edges are separated by the adaptive connecting domain labeling to analyze wear condition of each edge. Then, each edge is arranged regularly by the improved rotatory positioning. The cutting edge is extracted by the method of partial angle threshold to fit and calculate the bottom wear value. It is shown that the absolute values of errors on the maximum wear width are less than 0.007 mm by using the self-matching algorithm. In the case of severe wear and breakage, the absolute values of errors on the maximum wear width are less than 0.057 mm because of uneven reflected light. The system features high response speed, high inspecting accuracy, and anti-noise performance. It is proved to be able to increase the utilization of cutting tools and guarantee the quality of workpiece. This method is potential to guarantee the reliability of cutting tool in aerospace manufacturing. [ABSTRACT FROM AUTHOR]

The prediction precision of mechanics parameters such as rolling force and torque affects the yield, quality, cost, and benefit of products during the cold strip rolling. The lever arm coefficient is the core linking rolling force and torque, but there is no mathematical model of this in cold rolling. The distribution of rolling pressure and the change rule of lever arm coefficient under different reduction, forward and backward tension stress, deformation resistance, and friction coefficient in cold rolling are illustrated based on 3D (three-dimensional) elastic-plastic FEM (finite element model) simulation. The mathematical model of lever arm coefficient is built according to online measured data processed by BP (back propagation) neural network in the tandem cold rolling plant. The predicted rolling forces calculated on the basis of this model and upper bound method are consistent with online measured values. The proposed model provides valuable guidelines to determine the reduction and check the strength of the equipment such as rolls and stands. [ABSTRACT FROM AUTHOR]

As the basis for a flatness control system, flatness actuator efficiency describes an actuator's control ability, but it is difficult to obtain an actuator efficiency factor accurately through rolling tests because of the complicated subsidiary facilities of the mill. This paper proposes a novel simulation approach that is applied to obtain the actuator efficiency factors in terms of work roll bending, intermediate roll bending, and intermediate roll shifting for a six-high Universal Crown Control mill (UCM mill). A three-dimensional (3D) finite element model of the mill was developed to simulate the dynamic strip rolling process. The validation of rolling experiments shows that this model has enough precision, where the relative error of strip thickness between simulated values and actual values is less than 1.0%. The effects of the actuators on strip thickness profile, crown, edge drop, and elongation difference of longitudinal fibers were investigated. In the case of different actuator parameters, the curves of actuator efficiency factors were obtained and quantitatively descripted by truncated Legendre orthogonal polynomials. The mechanism of flatness control was studied based on an analysis of the actuator's influence rule on the elastic deflection of rolls and 3D distribution of rolling pressure. The results indicate that the curves of actuator efficiency factors have a symmetrical upside-down v-shaped distribution and contain the quadratic and quartic flatness components. The actuator efficiency factors of intermediate roll shifting have a nonignorable variation with the change of actuator parameters. This study is the first attempt to obtain actuator efficiency factors for UCM mill using an elastic-plastic finite element method. [ABSTRACT FROM AUTHOR]

In aerospace manufacture industry, cutting vibration is a key factor for surface quality and tool life during milling of thin-walled aluminum alloy parts, and the high-efficiency machining is limited seriously for this reason. In this research, the cutting layer's deformation was inhibited to reduce cutting vibration by optimal design of cutting edge structure. Base on the observation and imitation of corn leaf's teeth, the structure of groove and micro-blade of peripheral cutting edge was designed. The orthogonal cutting models were developed to analyze the cutting process by ABAQUS. Furthermore, comparative experiments of milling aluminum alloy 7050-T7451 were carried out to analyze the cutting force, vibration, surface roughness, and residual stress. The test and simulation results showed that the designed solid cemented carbide end mill based on bionics had a good effect for inhibiting the cutting layer's deformation. The fluctuations of cutting force, cutting vibration, surface residual stress, and surface roughness were reduced effectively. [ABSTRACT FROM AUTHOR]

To investigate the edge drop control characteristics of the roll contour on the taper segment of a taper-work roll, a three-dimensional roll stack-strip-tension coupling model was established with the finite element method, and the simulation model was verified using experimental data. The effects of the taper-work roll shifting (T-WRS) for different contours on the edge drop, center crown, flatness, and nonuniformity of the rolling pressure field unevenness were studied. The results indicated that the thickness difference caused by the combination of the roll contour and the work roll shifting (WRS) effectively compensated for the edge drop caused by the elastic deformation of the roll was the main way for T-WRS to reduce edge drop. Increasing the height of the roll contour inserted into the strip could significantly improve the edge drop control ability. However, it would also lead to increasing the trend of M-mode waviness defects and increase the peak of rolling pressure and the unevenness of the contact pressure between the rolls. Therefore, a novel approach for the roll contour evaluation was proposed by constructing the multi-objective function of the taper-work roll shifting. With edge drop control as the primary goal, the optimal range and suitable range of the WRS for different roll contours were calculated for the first stand of the tandem cold mill. [ABSTRACT FROM AUTHOR]

Titanium alloys are widely utilized in aerospace, automotive, biomedical and chemical engineering, etc., thanks to their excellent combination of high-specific strength, fracture, corrosion resistance characteristics, etc. However, titanium alloys are difficult-to-machine materials. Tool wear is one of the bottlenecks restricting their machining efficiency. A systematic study on the relationships among tool wear, chip morphology, and cutting vibration is inadequate. In this study, chip morphology and cutting vibration characteristics under different tool wear stages are examined using optical microscope, SEM, and vibration test system. The mechanism of tool wear in end milling titanium alloy is also investigated. Results indicate that with the progression of tool wear, the chip segment degree becomes more and more serious. The mechanism for this phenomenon is probed. Tool wear progression enlarges the cutting vibration which causes the friction force on tool/chip interfaces to increase, and this aggravates chip edge wear accordingly. On the contrary, the increase of chip segment degree induces the progression of cutting vibration and tool wear. Therefore, the aim of the present research is to investigate the sophisticated relationship. This will benefit for improving cutting efficiency and guaranteeing machining quality in end milling titanium alloy. [ABSTRACT FROM AUTHOR]

The cutting temperature and cutting force are some of the main factors that influence the surface quality of carbon fiber-reinforced polymer (CFRP). However, few investigations have been done on cutting temperature because it is difficult to capture the dynamic response of the temperature measurement system. Degradation of resin will occur within the machined surface or surface layer as the temperature exceeds the glass-transition temperature of the resin matrix. In this research, the relationship between cutting parameters and cutting temperature, cutting force were developed by response surface methodology (RSM). The experiments were designed using the tool-workpiece thermocouple technique. Taking into consideration the effect of the glass-transition temperature, the influence of cutting force and cutting temperature on surface quality of CFRP was analyzed. Analysis results showed that Spindle speed is the key parameter which influenced the cutting temperature while feed rate is the key parameter which influenced the cutting force in milling of CFRP. When the cutting temperature exceeds the glass-transition temperature ( T), the matrix cannot provide enough support to the fibers, and the machining quality of composite material is poor. [ABSTRACT FROM AUTHOR]

Laser cladding, which can increase the hardness and wear resistance of the used components, is widely used in remanufacture and sustainable manufacturing field. Generally, laser cladding layer should be machined to meet the function as well as the assembly requirements. Milling is an effective means for precision machining. However, there exist great differences of physical and mechanical performances between laser cladding layer and substrate material, such as microstructure, hardness, mechanical properties, etc. This produces some new milling problems for laser cladding layer. An insightful understanding of milling mechanism of laser cladding layer is inevitable. There still lacks the research on this subject, such as chip morphology and mechanical behavior, vibration during laser cladding layer milling process, etc. Thus, the change of chip morphology depending on the cutting parameters and microhardness variation was studied. Signal analysis methods of time and frequency domains of cutting forces and machining vibration were used to evaluate the milling characteristics of laser cladding layer. The microstructural analysis indicates that shear-induced lamella structures are the basic features for the chip free surface. The height-to-thickness ratio of saw-tooth chips increases with increasing cutting speeds and feeds. Microhardness profiles on the top surfaces of machined chip decrease from the back surface to the bulk chip, and the shear band shows increased hardness. The cutting force and machining vibration acceleration of laser cladding layer are higher than those of the KMN steel substrate at the same cutting parameters. The machining vibration is characterized by high vibration in the intermediate position of each layer and low vibration in the joint surfaces between layers. [ABSTRACT FROM AUTHOR]

The principal influence factors on the monolithic component deformation were investigated by finite element simulation simulation and experiment. Initial residual stress of the blank, machining-induced residual stress, and coupling action of these two effect factors were considered. To study the effect of blank initial residual stress on component deformation, chemical milling was used to remove the machining-induced residual stress on the machined surface of the components. The research results show that the initial residual stress in the blank was the main factor of deformation for three-frame monolithic beam, and the coupling action of the initial residual stress and machining-induced residual stresses aggravated the deformation. The deformation caused by machining residual stress accounted for about 10 % of the total deformation of the component, and the deformation caused by the blank initial residual stress accounted for 90 % of the total deformation of the component. The finite element simulation results were compared with experimental results and found to be in good agreement. [ABSTRACT FROM AUTHOR]

Clearance of end mills has great impact on the performance of milling, and therefore a high demand for its machining theory and process is put forward. Based on the analysis of practical machining process, enveloping theory, principles of spatial geometry are introduced to establish the clearances processing model, as well as considering the geometries, orientations, and locations of wheels used to machine the clearances with convex, eccentric, or elliptic shapes. Accordingly, limitations of wheel geometry and location to machine a desired clearance are discussed. A commercial computer aided design system with API function programming is used to visualize the machining process. The solid model is finally obtained. [ABSTRACT FROM AUTHOR]

Helical groove is one of the key structures of end mills. Its grinding process is the hardest and most time-consuming in end mill machining. According to the practical groove-grinding process, a Boolean method to simulate the groove-grinding process is proposed in this paper. The groove model is obtained with the known wheel geometry by a sequence of Boolean operations. Accordingly, the wheel used to machine a desired groove is deduced with the similar method. Based on the Boolean operation results and principles of differential geometry, contact lines of the wheel and groove are illustrated and calculated to optimize the groove-grinding process. Wheel positions relative to the blank are described by a sequence of mathematical coordinates. Wheel profile expressions are built with the corresponding transformation matrixes including groove geometry transformation matrix, cutter tip transformation matrix, and start processing position transformation matrix. Some simulated examples are included to illustrate the presented method. [ABSTRACT FROM AUTHOR]

Drilling-induced delamination of composite materials is a key factor that affects the quality of subsequent machining. To investigate the developing process of delamination, experiments with different drilling depth are conducted. In order to observe the delamination of different cross-sections in radial direction of the hole, the grinding method is adopted. Three-dimensional morphology of delamination at the exit of hole is obtained. The regularity of delamination with the change of drilling depth is analyzed, and the existence of 'hidden delamination zone' is obtained finally. Due to the rebound effect of hole diameter and the inverted cone of drill guide section, the 'hidden delamination zone' will be generated under the condition that the edge of delamination area is compressed tightly again. The critical thrust force of delamination is also studied, and it is proved to be correct. [ABSTRACT FROM AUTHOR]

An investigation was reported on the cutting temperature in milling Ti6Al4V by applying semi-artificial thermocouple. ANOVA was conducted on the experimental results, and regression models were obtained. Analysis results showed that the tool temperature and workpiece temperature performed a similar rising trend with the increase of cutting parameters, including cutting speed, feed rate, radial feed, and axial feed. And their influence degrees decreased successively. The cutting force with different cutting parameters was also measured, and the relationship between cutting temperature and cutting force was discussed. It was found that cutting temperature and cutting force obtained in the experiment had the same fluctuation feature. Therefore, the cutting force and cutting temperature could complement each other for monitoring and analysis of the cutting process. [ABSTRACT FROM AUTHOR]

This paper presented a study of the relationship between cutting force and tool flank wear of solid carbide tool during the wet end milling Ti6Al4V. The modeling of 3D cutting force in end milling considering tool flank wear was discussed, which showed that for the given cutting conditions, tool geometries, and workpiece material, cutting force under the tool flank wear effect can be predicted easily and conveniently. In addition, the experimental work of end milling Ti6Al4V with solid carbide tool was developed to investigate the relationship between cutting force and tool flank wear, and comparison between experimental results and predicted results was discussed. The results showed that the proposed mathematical model can help to predict 3D cutting force under the tool flank wear effect with high accuracy. [ABSTRACT FROM AUTHOR]

Despite the recent developments in non-conventional manufacturing approaches, machining is still a prominent technique for the mass production of metallic components. However, given the difficult-to-machine nature and high heat generation during machining of Hastelloy-X, there is a lack of comparative investigations that can provide basics for sustainable process management in machining of Hastelloy-X. Different sustainable cooling approaches (dry, minimum quantity lubrication (MQL), cryogenic) and their impact on Hastelloy-X machining process behavior have been investigated in this study. Machining parameters such as constant cutting speed of 124 mm/min, feed rate of 0.15 mm/min, and cutting depth of 0.1 mm and cutting force, cutting temperature, and surface roughness were consider as output responses. It was observed that with the adaptation of cryogenic conditions, cutting forces can be reduced 5 to 14% in comparison with MQL and dry conditions. Cutting temperature and surface roughness values were however observed to be largely reduced with cryogenic cooling. The chipping and adhesion were found to be reduced with cryogenic cooling due to the reduction in workpiece softening behavior and increase in hardness to cutting tool. [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]

Both the product and the manufacturing process must be sustainable in today's modern world. Traditional machining methods are undesirable when working with heat-resistant alloys. These methods could be more efficient and can be maintained over time. As the world progresses to sustainability, many people are working to integrate this concept into the industrial process. In the manufacturing industry, the evaluation of sustainability carries immense significance in ensuring product quality, promoting operators' safety and well-being, and preventing any form of environmental degradation or pollution. Concerning this regard, the main objective of the present study is to assess the sustainability parameters during the drilling of Alloy 20 material under different environmental conditions such as minimum quantity lubrication (MQL) and cryogenic and hybrid methods. The study is conducted in two stages, and in the first stage, the most impactful sustainable indicators, i.e., energy consumption, carbon emissions, total cycle time, and cost, have been evaluated. In the second phase of the investigation, the machining analysis of surface roughness, cutting forces, and circularity was determined under different conditions. The results showed that the hybrid cooling condition exhibited better technical, quality, and economic sustainability. Thus, it is important to note that selecting appropriate cooling conditions can contribute to achieving sustainability in manufacturing processes and that the hybrid cooling method aids industries in moving towards sustainable production systems that, in turn, contribute to a more environmentally conscious and efficient economy. [ABSTRACT FROM AUTHOR]

Rational parameters for the minimum quantity lubrication (MQL) are essential to reduce cutting temperature and extend tool life during titanium alloys' milling processing. However, little research has been done on the effect of nozzle elevation angle on Ti-6Al-4V milling. This article's objective is to experimentally elucidate the impact of various MQL parameters, including oil flow rate, nozzle distance, and nozzle elevation angle in the end-milling of Ti-6Al-4V. Response surface methodology (RSM) analyzes MQL parameters' influence on the cutting temperature, milling force, and acceleration. Results demonstrated that cutting temperature first decreases and increases with the increase of the oil flow rate increased from 30 to 250 ml/h. When the nozzle distance is either too large or too small, the measured cutting temperature, cutting force, and acceleration are higher than those measured at a nozzle distance of 60 mm. The nozzle elevation angle is the predominant factor affecting the experimental results. And proper nozzle settings can reduce the cutting temperature by 15 °C, the cutting force by at least 5.6%, and the acceleration by 8.9%. [ABSTRACT FROM AUTHOR]

Cutting fluid used in machining is under investigation to check the achievement of sustainability and the cleaner process by the machining process. Many attempts were made to find new cooling strategies as an alternative to the existing cooling methods. Cryogenic cooling was an efficient method to move towards sustainability for machining any materials and to ensure green machining. Machining of Al6082 HMMC has been carried out under distinct cutting environments. The fallout of these cutting environments was studied based on parameters like surface roughness, cutting temperature, chip morphology, and tool wear. The application of cryogenic CO2 substantially reduced the tool wear by 37% and 48% when compared to MQL and wet conditions. The SEM image of the worn tool disclosed that adopting the cryogenic cooling technique led to less crater wear and prevented the peeling of the tool layer to some extent. The impressive cooling effect of cryogenic cooling also produced a good surface finish on the machined surface compared to the other cooling environments. Thus, cryogenic cooling proved to be trustworthy in all the output parameters. [ABSTRACT FROM AUTHOR]

The work rolls of CVC rolling mill usually adopt S-shaped roll profile curve in the rolling process of plate, which changes the contact between the rolls and causes the contact pressure distribution between the rolls to be uneven. The peak of the contact pressure between the rolls appears at the end of the roll, which leads to peeling or "meat loss" at the end of the roll and poor plate crown control effect. To solve those problems, a CVC rolling mill backup roll profile curve with parabolic chamfer was proposed, and the fusion model of plate crown based on mechanism and data-driven models was developed. Combining the parameters of the CVC roll profile curve, the theoretical calculation formula of the backup roll chamfering was deduced. According to the actual data of the plate rolling mill, the parameters of different types of backup roll chamfering were determined, and the distribution of contact pressure between the rolls under different backup roll chamfering was calculated and analyzed by finite element model. Based on the new parabolic chamfer curve of backup roll, the rolling force setting model based on Extreme Learning Machine (ELM) and roll wear model based on Genetic Algorithm Artificial Neural Network (GA-ANN) were constructed by using the nonlinear fitting ability of machine learning algorithm. Then, the predicted results of rolling force and roll wear were taken as the input variables of plate crown prediction. At the same time, the roll system deformation model and roll bending force model based on mechanism model were introduced as inputs to construct the plate crown Convolutional Neural Network (CNN) model based on mechanism and data-driven fusion. The simulation results show that the parabolic chamfer can significantly reduce the pressure between the backup rolls. When the rolled strip width is 2000 mm, 2400 mm, and 2800 mm, the parabolic chamfer can reduce the peak contact stress between the rolls by 8.6% and 10.8%. When the rolling bending force is 1600kN, 2100kN, and 2600kN, the parabolic chamfer can reduce the peak contact stress between the rolls by 8.6%, 8.9%, and 9.1%. The hit ratio of plate crown increased from 90.4% to 96.5%, and the product degradation rate caused by the shape problem decreased by 35.5%. [ABSTRACT FROM AUTHOR]

An accurate description of the metal flow behavior during wedge zone deformation is key to the stability of the endless strip production rolling process. To predict the flatness distribution based on the law of volume invariance, a flatness calculation model of the wedge zone during the flying gauge change (FGC) process was established by considering the metal transverse flow. Furthermore, the effect of different rolling parameters on the flow of metal in the wedge zone was investigated using a combination of this model with a 3D finite element model. In addition, the influences of the reduction rate, roll crown, and friction coefficient on the flatness and metal lateral flow were analyzed and discussed. Finally, the numerical results provided by the finite element model were compared with the computed results of the flatness distribution to illustrate the effectiveness and stability of the proposed model. [ABSTRACT FROM AUTHOR]

Tool condition monitoring (TCM) is extremely important to ensure production efficiency and workpiece quality. It is crucial to extract and select suitable features from raw signals to improve the robustness and feasibility of TCM systems. This paper introduces a cutting force singularity analysis approach for TCM in milling, which correlates tool wear states with force waveform variations. The Holder exponents (HEs) were selected as the index of singularities. HEs are calculated by wavelet transform modulus maxima (WTMM). The raw signal is de-noised based on WTMM estimation, which can effectively preserve singularities compared with traditional filters. Fisher's discriminant ratio (FDR) is employed to rank the discriminant capability of statistical features of HEs. It is found that means of HEs and quantities of singular points estimated from feed forces Fx show the strongest class-discriminant ability. Then, these features were chosen as training samples to propose a TCM approach based on the support vector machine (SVM). Experimental results indicate that this approach provides reliable and effective advice for tool change. [ABSTRACT FROM AUTHOR]

The incremental sheet forming (ISF) is an innovative dieless forming process featured with high formability and short lead time which is suitable for rapid prototyping and small volume production. The integration of ultrasonic (US) vibration into the ISF process can significantly reduce the forming force and bring other benefits. In this work, the impacts of process parameters including the sheet material, US power, feeding speed, and tool diameter, on force reduction and temperature increment were studied. The force reduction contains two components—the stress superposition-induced force reduction and acoustic softening-induced force reduction. The stress superposition-induced force reduction was analyzed by finite element simulation while the total force reduction was detected by experiments since currently, the unknown mechanism of the acoustic softening cannot be modeled. The temperature increment was measured by a high-speed infrared camera. The results show that the force reduction can go up to 56.58% and the temperature increment can be as high as 24.55 °C. In general, the material with a higher yield stress results in a higher force reduction and a higher temperature increment. A higher US power or a lower feeding speed can significantly enhance the force reduction and the interface temperature increment. The tool with a smaller diameter has a comparable effect as a larger tool, but a larger vibration amplitude is required. [ABSTRACT FROM AUTHOR]

The next generation aircraft industry looks upon the multi-layered material structures. In this research work, conventional drilling technique is incorporated in assembly process for the stack material. However, in drilling process, chips play a significant role for chip tool life but the chip breaking mechanism is still unsolved, the key challenge of making high-quality hole and hole surface integrity for hole making of multi-layered material. To illustrate this issue, a series of drilling experiments were conducted on Al/Al stacks and Al/Ti Stacks with double cone drill. The objective was to examine the effect of process parameter, and influences of the double cone drill bit geometry on output response such as chip formation and chip breaking mechanism were investigated. Then, the effect of gap between Al/Al stacks and Al/Ti stacks materials respective chip formation as they flow away was probed. Surface roughness was measured by non-contact-type 3D laser scan microscope system. It was observed from the experiment that surface roughness value decreases from 4.06 to 2.59 μm with increasing cutting feed. The scanning electron microscope (SEM) analysis was carried out to study the chip morphology. Results demonstrated that upper-layer surface integrity can be improved by selecting suitable tool angles and process parameters. [ABSTRACT FROM AUTHOR]

Titanium alloys are attractive materials for aerospace, biomedical and chemical engineering due to their excellent combined performance of high specific strength and fracture resistant characteristics. Drilling titanium alloys is essential to the bolted/rivet connection in the assembly of aerospace parts. This paper outlines a comprehensive analysis of drilling characteristics and hole quality/integrity assessment following drilling titanium alloy Ti6Al4V without coolant under different machining parameters. The experimental results show that hole quality can be improved by proper selection of cutting parameters. This is substantiated by monitoring thrust force, hole diameter, circularity, chip formation, and surface finish. It was observed that the thrust force increased rapidly with respect to feed rate, which was increased by 2.5 times when the feed was increased from 0.05 to 0.13 mm/r as a constant cutting speed of 40 m/min. In addition, the circularity was found to be around 4 μm at low feed rate, when the feed was increased the circularity increased to 10 μm. The experimental results also indicated that the shape and the size of chips were strongly influenced by feed rate. Observation on the subsurface of drilled workpiece indicated a severe plastic deformation under different cutting conditions. This study demonstrates that using proper process parameters plays an important role in improving machining efficiency and guaranteeing quality in dry drilling titanium alloy. [ABSTRACT FROM AUTHOR]

In hot strip rolling process, rolling schedule setup, geometrical accuracy (thickness and profile), and even the final product homogeneity of mechanical properties are affected by the automatic control, and the rolling force and torque are the prerequisite in the control process. A new cosine velocity field is firstly proposed in this paper to get the values of the required minimum rolling force and torque. The field and equal area (EA) yield criterion are used to integrate the internal plastic deformation power. Using the co-line vector inner product method, the friction power is analyzed. Finally, the analytical expressions of rolling force, rolling torque, and stress effective factor are obtained. The theoretical predictions of rolling forces are compared with on-line measured ones in a hot strip rolling plant and other researchers' models. Results show that the calculated rolling forces are in fair agreement with the actual measured ones, and the proposed solution is considered to be applicable for solving hot strip finish rolling. [ABSTRACT FROM AUTHOR]

Rubber pad forming is an advanced processing technology to form the metal sheet. The micro-channel on the plate can be formed by both rubber pad and the metal mold. With the development of micro-channel, a two-step micro-channel has been applied in more and more fields such as fuel cell bipolar plate. However, little attention was given to the forming strategy for these unique channels. In this paper, the rubber pad forming process is used to form the entire SS304 sheet with two-step channels. In order to design the micro-channel structure with good formability, the main parameters of the two-step micro-channel are discussed through finite element modeling (FEM) and forming experiment. Not only for the geometric parameters for structures like length, width, edge chamfer, and the height ratio of first to second step, but also for the spatial distribution like the number and distance of two-step micro-channels in the entire plate. In addition, MATLAB is used to study the influences on the final forming results because of the various parameters. And then, the plates can be precisely formed when the structure is suitable, while micro-channels with unsuitable structure cannot be formed as designed. Finally, based on the FEM and forming experiment results, a design strategy is provided in the conclusions. [ABSTRACT FROM AUTHOR]

Both the mass and centrifugal force can be reduced by the hollow structure in blade. Also, the working efficiency of the engine can be improved by this hollow structure, but this structure is complicated and difficult to be formed. A pressing process of hollow blade with low melting point alloy as mandrel is proposed. The results show that the shape of the hollow blade can be controlled better by filling the low melting point alloy. The supporting structure has a great influence on the forming effect of unfilled low melting point alloy blade. The more supporting structures, the better the forming effect. The interface between the blade and the low melting point alloy cannot be bonded, so this processing method can be applied to practical production. [ABSTRACT FROM AUTHOR]

Atomized spray cutting fluid (ASCF) is a complex machining technology that results in increased productivity, improved surface quality, longer tool life, and cost savings. The purpose of this study is to investigate the effect of cutting process parameters on Inconel 718 alloy turning in dry and ASCF cutting environments. These two cooling environments' essential machining indices, such as surface roughness, machining cost, power consumption, and tool life, were investigated. The cutting parameters were adjusted using desirability functional analysis, and two types of multicriteria decision-making (MCDM) methods were investigated: additive ratio assessment method (ARAS) and combinative distance-based assessment technique (CODAS). Both MCDM approaches yielded identical results, with the best settings being a cutting speed of 200 m/min, a feed rate of 0.08 mm/rev, and a depth of cut of 0.2 mm in an ASCF environment. ASCF machining considerably minimises the surface roughness, machining cost, power consumption and maximises the tool life by around 16%, 51%, 17%, and 48%, respectively, compared with dry machining. [ABSTRACT FROM AUTHOR]

Surface micro-channels with different structures have a variety of functions. In order to further develop these functions, micro-channel design and forming process are constantly being innovated. In this paper, the advanced rubber pad forming technology is used to manufacture the new two-step micro-channel structure. Forced convection can be caused by this kind of micro-channel in three dimensions of the gas, which can reduce the flow rate and make the gas evenly distributed. Therefore, it can be used in bipolar plates of PEMFC (proton exchange membrane fuel cell). According to the driving mode, forming mode is divided into active forming and passive forming. The metal plates formed in these ways are studied, and the advantages and differences of forming results are discussed. The 304 stainless steel sheet with the thickness of 0.1 mm is used in the manufacturing process. Polyurethane with shore A70 hardness and 60 mm total thickness is selected as rubber pad. And then, two models of forming two metal plates simultaneously in one time are presented. In order to verify the accuracy of the model, finite element method and forming experiment are carried out. It is shown that the rubber pad forming process is a feasible process for producing multiple two-step micro-channel metal plates in one time. [ABSTRACT FROM AUTHOR]

Aluminum alloy profiles are widely used in traffic transportations. Both enough strength and precise shape are needed in these profiles. A novel ECAP with rubber mandrel is used to strengthen complex U-groove profiles. This ECAP is comprehensively researched by analytical and simulation as well as experimental methods in all the three situations "N," "U," and "C." The shape control mechanism will be received by analytical method. The thicknesses vertical to the deformation plane can be controlled by plane deformation, while the thicknesses parallel to the deformation plane can be controlled by the constant thickness ratio. The simulations and experiments will be both used to verify the shape control effects. Finally, there will be more stresses in situation "U" based on the stress nephograms. The shape control results in situation "C" are better than these in situations "N" and "U" from both simulations and experiments. Based on the research in this paper, U-groove aluminum profiles are suggested to be formed by ECAP with rubber mandrel in situation "C." This may be a strategy for U-groove aluminum profiles formed by ECAP. [ABSTRACT FROM AUTHOR]

An accurate approach of the instantaneous undeformed chip thickness is a key issue for analyzing milling process. The presented models for approximating instantaneous undeformed chip thickness are oversimplified and complex for use in academic and manufacture practice. In this paper, a new model for determining the undeformed chip thickness in milling process with higher accuracy is proposed. According to the true trochoid path of tool tooth, the true instantaneous undeformed chip thickness can be derived by solving the deduced transcendental equation. An iterational algorithm is used to approach the value in the transcendental equation with infinitesimal calculation error. Our main contributions include that the accurate positions of the geometric points of the undeformed chip profile with different level of width of cut are analyzed and derived, as well as the accurate undeformed chip thicknesses of the chip cross-section profile are approached by iterative algorithm. Case studies with different parameter combinations show that the new model has a higher accuracy compared with the presented models. With this innovative approach, a method of accurate prediction of the geometric profile and thickness of the undeformed chip profile in milling process is provided. [ABSTRACT FROM AUTHOR]

In order to further improve the control accuracy of thickness, crown and tension in hot strip finishing mill, a multivariable optimizing strategy based on inverse linear quadratic (ILQ) control theory is proposed in this paper. First, the state space model of hot rolling process is established based on the basic dynamic mathematical model of rolling process and measured data collected from a certain plant. Then, the new ILQ control strategy is designed for the thickness, crown and tension control system in the complex rolling process, and the response performance and anti-interference performance of ILQ controller and PI controller were tested. The results show that the proposed ILQ control strategy has excellent control performance with the maximal overshoot 24.13% smaller than that of PI controller when strip crown, thickness and tension step signals are added simultaneously, and the ILQ control strategy has certain guiding significance for the actual production of hot rolling. [ABSTRACT FROM AUTHOR]

NiTi shape memory alloy products are becoming more and more popular in many areas. But owing to the unique characteristics of NiTi shape memory alloys, it is still considered restrictive by the traditional machining methods of producing NiTi shape memory alloys for finished products. Flood coolant and cryogenic with liquid nitrogen (LN2)–assisted machining is desired to improve machinability of material in the turning procedure. Experiments were conducted to examine the influence of cooling conditions (dry, flood, and cryogenic LN2) on turning NiTi shape memory alloys at different cutting speeds. Tool wear, cutting force, and surface integrity were selected as evaluation characteristics to explore the effects of different cooling methods and the stress-induced martensitic phase during the turning process. The study shows that the appearance of the stress-induced martensitic phase during the turning process harms the machinability of NiTi shape memory alloys. Flood conditions accomplish lower tool wear and cutting force at 15 m/min. Cryogenic conditions achieve higher machinability at 125 m/min. [ABSTRACT FROM AUTHOR]

To study the transverse temperature uniformity with transverse flux induction heating (TFIH) during endless strip production (ESP) rolling, a coupled electromagnetic-thermal finite element model of transverse flux induction heating is established. The initial temperature distribution at the TFIH inlet is taken into consideration, which is the basis of subsequent numerical studies. Magnetic screens are designed to weaken the influence of edge overheating, and the influence of magnetic shielding amounts on temperature uniformity is discussed. Moreover, an evaluation criterion is provided to determine the temperature uniformity. Furthermore, the effect of different shielding amounts on the edge temperature is studied. An ideal temperature distribution at the TFIH outlet is obtained based on a model combining various shielding amounts, and the temperature standard deviation of this method is 2.01% lower than the traditional arrangement of magnetic shielding amounts. Actual data are collected to verify the results of the proposed model. The temperature deviation between the middle and edge is approximately 12°C, and the temperature uniformity is enhanced with the optimized combination of magnetic shielding amounts. [ABSTRACT FROM AUTHOR]

The vibration reduction mechanism of variable pitch end mills was analyzed by the theory of energy balance of the frequency spectrum line. The variable pitch mill can reduce the forced vibration in the cutting process due to the uniform distribution of frequency spectrum line energy and lower peak energy of the cutting force. Aimed at the vibration phenomenon which restricted the efficiency in cutting aero material titanium alloy, high-speed cutting experiments of titanium alloy Ti6Al4V were set with variable and equal pitch mills under dry and down-milling environment. The influences of cutting speeds on cutting forces and tool vibration were analyzed at time domain and frequency domain, respectively, by which the vibration reduction mechanism of variable pitch mill was verified. Due to the misalignment of end mill no. 3, high-level cutting forces and tool vibration were caused by the unequal cutting load on each edge. It is found that severe tool vibration was produced under the cutting speed of 150 m/min because of low-frequency resonance in the cutting process. [ABSTRACT FROM AUTHOR]

In metal cutting processes, the chatter may cause fast wear of tools and poor surface quality of the processed parts; it can happen on different cutting parameters, but how do we identify the chatter and how do we select suitable cutting parameters to avoid chatter at high material removal rate (MRR). In this paper, the signal processing methods such as time domain, frequency domain, and time-frequency domain analysis are introduced. The signals of cutting force that were collected in milling titanium alloy Ti-6Al-4V at variable cutting speeds varied from 80 to 360 m/min; signal analysis methods such as time domain, frequency domain, and time-frequency domain were put forward. Further analysis results reveal that the chatter occur when cutting speeds are 240 and 360 m/min, when the maximum value of cutting forces increase by 61.9-66.8%, the standard deviation increase by 84.1-86.1%, and the surface roughness increase by 34.2-40.5% compared with that of at 80 m/min. Detail signal d2 is employed to monitor cutting stability state from the result of wavelet analysis. [ABSTRACT FROM AUTHOR]

Chatter may cause fast wear of tools and poor surface quality of the workpieces at high cutting speed and it will happen on different process parameters; how do we select the suitable cutting speed to suppress the chatter? In this paper, a signal analysis method for milling force and acceleration is adopted to identify chatter, which can obtain the results not only in frequency of chatter but also in the contribution for milling force at different frequencies. Through the milling experiment, the machining vibration behaviors of milling Ti-6Al-4V with variable pitch end mill were investigated. Milling force and acceleration signals obtained from experiment were analyzed and compared at stable and unstable milling processes. The experimental results show that when the chatter occurs, milling forces were found to increase dramatically by 61.9-66.8% compared with that of at stable cutting; machining surface quality became poor and machined surface roughness increases by 34.2-40.5% compared with that of at stable cutting. [ABSTRACT FROM AUTHOR]

Rapid melting and solidification of powder particles through a high-power laser is the characteristic feature of selective laser melting (SLM), which controls the material and physical properties of fabricated components. Considering the multi-track multi-layer nature of an actual SLM process, an investigation of thermal behavior and melt pool morphology in multi-track multi-layer SLM of the 316L steel is presented in this paper. The SLM process of a four-layer component with multiple tracks was modeled. Element birth and death technique was used to simulate the layer built-up process. The established FEM model was used to investigate the variations in thermal variables and melt pool morphology with increasing number of layers. Moreover, the influence of various processing parameters in a multi-track multi-layer SLM was also studied. The results show that maximum melt pool temperature, melt pool width, and melt pool depth increase with increasing number of layers, whereas heating rates and cooling rates decrease with increasing number of layers. Compared with the previous layer, melt pool lifetime was observed to have a decreasing trend for layer 2 and increasing trend for layers 3 and 4. An increase in melt pool depth and decrease in melt pool width was observed by increasing hatch spacing. Furthermore, it was found that increasing laser power and scanning speeds both increase the heating and cooling rates. [ABSTRACT FROM AUTHOR]

Improving mechanical properties and maintaining shape precisions are both significant for the further developments of aluminum alloy profiles. A new kind of ECAP with rubber mandrels can be innovatively used to form these alloy profiles in recent years. The profiles can be maintained as their initial shapes after pressing through the channel. At the same time, their mechanical properties can be improved. In this paper, analytical method is firstly used to find the mechanical mechanism during this process. Both finite element simulation and physical experiment are used to verify these results obtained by the analytical model. Except for the head and tail parts of the profiles, the shape of middle parts can be maintained well. Based on the stress delivered, severe plastic deformation can be applied in forming process of complex profiles. Better mechanical properties and good shape precisions can be creatively realized in complex profiles at the same time. [ABSTRACT FROM AUTHOR]

In order to reduce misalignment, enhance tight tolerance, and improve machining efficiency, a novel double cone integrated tool was developed and experimentally investigated during one-shot drilling of aluminum and aluminum alloy stacks in this paper. This special tool geometry can finish drilling, reaming, and countersinking processes at the same time. Its machining properties were comparatively evaluated with a standard twist drill (reference drill) by means of a series of experiments. Experimental results highlighted the influence of tool geometry on cutting force and vibration signals for drilling, reaming, and countersinking processes, respectively. The results indicated that the double cone integrated drill can induce a little larger thrust force than a reference drill due to its longer cutting edge. In addition, the chip morphologies generated by different processes and cutting variations also have been comparatively analyzed. The double cone drill under a larger feed rate was prone to produce smaller chips. Furthermore, the double cone drill can achieve smaller burrs, better surface integrity, and lighter tool wear compared with reference drill. The information obtained from this study can provide a better understanding of the one-shot drilling process and guidance for achieving higher efficiency and better hole quality. [ABSTRACT FROM AUTHOR]

The cutting force is one of the main factors that influence the processing quality of fiber-reinforced polymer composites (FRPs). However, since the material removal mechanics of composites are quite different from those of metals, the cutting mechanisms of metals cannot be directly used for orthogonal cutting of composites. This paper aims to develop a novel force prediction model without the need to run any experiments. The deformation of fiber and the support of surrounding matrix are analyzed based on the minimum potential energy principle and the dynamic equilibrium. A force prediction model of FRP cutting is obtained for fiber orientations ranging from 0 to 90° + γ. The relevant experiments conducted showed the validity of the proposed model. The influence of rake angle and clearance angle on cutting force is analyzed. [ABSTRACT FROM AUTHOR]

This paper presents a detailed literature review on the current research of incremental sheet forming relating to deformation mechanism, modelling techniques, forming force prediction and process investigations. First, a review of the fundamental deformation mechanism and formability in incremental sheet forming (ISF) is provided. Subsequently, the modelling techniques for ISF are reviewed and categorised into two approaches: analytical modelling and finite element modelling. Special interest is given to a critical review regarding the forming forces analysis and prediction during the process. Then, previous publications related to geometric accuracy, surface finish and forming efficiency in ISF are reviewed. Finally, several potential hybrid incremental sheet-forming strategies are discussed. This leads to a statement of conclusion which may act as an inspiration and reference for the researcher. [ABSTRACT FROM AUTHOR]