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In this study, the thermal model of the creep feed deep profile (CFDP) grinding process of a small-module gear was established regarding the spatial interaction between the workpiece and grinding wheel, as well as the thermal boundary and the energy partition. A 3D dynamic finite element simulation of small-module gear CFDP grinding was carried out by utilizing the element birth and death technique. The validation experiments aided the specially designed thermocouples in that the grinding temperature on both sides of the tooth groove could be measured simultaneously, which demonstrated a satisfactory agreement with the experimental findings. The average difference was approximately 10%, which proved the feasibility and accuracy of the simulation. The effects of three possible geometric structures for both sides of the tooth groove being processed on the grinding temperature distribution were discussed based on the validated finite element model. This study is expected to enhance comprehension of the temperature distribution in the CFDP grinding of a small-module gear and offer recommendations for optimizing the process parameters in the precision machining of a small-module gear. [ABSTRACT FROM AUTHOR]

Structured grinding wheel has obvious advantages in reducing grinding force, and the structural parameters of grinding wheel have important influence on the reduction of grinding force. In order to determine the influence law of structural parameters on grinding force, the following theoretical modeling and experimental research work are carried out in this paper. Firstly, single grit scratching experiments of the workpiece material are carried out to determine the critical cutting depth for ploughing and cutting transition. The influences of structural parameters on the maximum undeformed chip thickness and the average contact arc length during grinding are analyzed in detail. The abrasive grains are simplified into a cone with an apex angle of 120°, the surface topography model of the structured grinding wheel is established according to the measured results of the distribution law of abrasive grains on the surface of the grinding wheel and the structural characteristic parameters. Combined with the grinding force model of single abrasive grain in ploughing and cutting stages, the grinding force calculation model of straight groove structured grinding wheel is established during the grinding process. Finally, grinding experiments are carried out to verify the accuracy of the theoretical grinding force model. The results show that the calculated values of grinding force are in good agreement with the experimental values, and the maximum calculation errors of tangential grinding force and normal grinding force are 14.5% and 11.8%, respectively. It is found that when the intermittent ratio of structured grinding wheel is constant, the groove width has little influence on grinding force. However, when the groove width is constant, the intermittent ratio has a great influence on the grinding force, and with the increase of the intermittent ratio, the grinding force decreases obviously. [ABSTRACT FROM AUTHOR]

A new method of ultrasonic-assisted electrolyte plasma polishing (UEPP) is proposed to solve the problem that the oxidation layer generated on the anode workpiece surface in the process of electrolytic plasma and polishing (EPP) cannot be removed completely, which affects the polishing efficiency and surface quality of the workpiece. Firstly, the polishing mechanism of UEPP is described and set up an experimental platform. Taking SUS304 stainless steel as the experimental object, comparative experiments of UEPP and EPP polishing are carried out to verify the beneficial effect of ultrasonic vibration on improving polishing efficiency and polishing quality. The results show that under the same polishing parameters, the introduction of ultrasonic vibration can improve the polishing efficiency by nearly 30%. After UEPP process, the workpiece has better surface texture, the number of surface scratches is greatly reduced, and lower surface roughness can be obtained. In addition, 40 kHz is the best ultrasonic vibration parameter. The optimization experiments of UEPP polishing process parameters are further carried out. For SUS304 stainless steel, the optimal polishing process parameters are power supply voltage of 250 V, polishing solution concentration of 4%wt, polishing solution temperature of 80 ℃ under 40 kHz ultrasonic-assisted conditions. The surface roughness of the experimental workpiece can be reduced from the initial Sa0.5 μm to Sa0.02 μm after 40 min of polishing under the optimized process parameters. [ABSTRACT FROM AUTHOR]

Electrochemical polishing (ECP) is widely used for scratch- and damage-free finishing of metal components. Though the polishing effect of ECP has been confirmed in many researches, the influence of polishing parameters on evolution of surface roughness is still ambiguous owing to the use of different ECP systems. In this paper, the universal factor determining the evolution of surface roughness during ECP is studied by theoretical analysis as well as experiments. Theoretical analysis based on viscous layer mechanism demonstrates that the material removal thickness is the key parameter governing the roughness evolution of the polished surface regardless of other parameters including the voltage and current and electrolyte concentration. A series of experiments were designed and carried out to verify the proposed hypothesis. Both the experimental results and already published researches proved the validity and universality of the newly developed hypothesis on surface roughness evolution. This work is of great significance for further understanding the finishing mechanism of ECP and process control for its practical applications. [ABSTRACT FROM AUTHOR]

In order to improve the efficiency and uniformity of bond removal, a finite element model of multi-pulse laser ablation was established, and process experiments of laser ablation and sharpening were carried out in this paper. The results show that the efficiency of bond removal increased linearly with the increase of laser power density. Increasing the spot overlap ratio could improve the efficiency of bond removal, and changing the line overlap ratio had almost no effect on the efficiency of bond removal. Increasing the spot overlap ratio and the line overlap ratio was beneficial to improve the uniformity of the bond removal and ensure the uniformity of the grain protrusion height. The established finite element model could provide theoretical basis and data reference for determining the process parameter window and predicting the surface topography when performing the laser sharpening of grinding wheel (not limited to the bronze-bonded diamond grinding wheel), thereby saving cost and improving efficiency. [ABSTRACT FROM AUTHOR]

To address the significant subsurface damage of a workpiece after grinding by a coarse-grained wheel, the research on nanosecond ultraviolet laser micro-structuring of a coarse-grained diamond-grinding wheel was carried out, and the influence of process parameters on the depth and width of the groove, the micro-structuring efficiency, and the qualification rate of micro-structured grains were explored. The results show that the single-pass laser circular cutting method cannot achieve the desired groove size even with an arbitrarily large number of scanning cycles. The multi-pass laser circular cutting method can effectively improve the micro-structuring efficiency, and the width and depth of the groove increased and decreased respectively with the increase of the pass spacing. The qualification rate of micro-structured grains was related to the groove spacing, the distribution of the grains on the surface of the grinding wheel, the grain diameter, and the groove width. Under the assumption that the grains were evenly distributed on the surface of the grinding wheel, the qualification rate first increased and then decreased with the increase of the groove spacing. [ABSTRACT FROM AUTHOR]

Considering the relatively poor surface and subsurface quality of workpieces that are ground by coarse-grained grinding wheels, the nanosecond ultraviolet laser micro-structuring of coarse-grained diamond grinding wheels and the grinding performance of micro-structured grinding wheels were investigated in this study. In addition, the effect of two processing sequences on the topographical characteristics of the grooves and the effect of the groove angle ( α) on the surface roughness ( R ) of the ground workpiece were explored. Furthermore, the surface quality of workpieces that were ground by micro-structured (V-shaped and W-shaped patterns) and non-structured diamond grinding wheels and the grinding ratio ( G) of the grinding wheels were comparatively analyzed. The results demonstrate the following: Compared with the grinding wheel that was subjected to micro-structuring followed by sharpening, the surface of the grinding wheel that was subjected to sharpening followed by micro-structuring had a more integral groove structure. Neither an overly large α nor an overly small α was favorable for improving the surface quality of the workpiece that was ground by a micro-structured grinding wheel. When α = 60°, the minimum R of the workpiece was attained. The R of the workpieces that were ground by the grinding wheel with a V-shaped pattern (grinding wheel A) was 17-31% less than the R of the workpieces that were ground by the non-structured grinding wheel (grinding wheel C). The R of the workpieces that were ground by the grinding wheel with a W-shaped pattern (grinding wheel B) was 32-41% less than the R of the workpieces that were ground by grinding wheel C. The grinding performance of the micro-structured grinding wheels was related not only to the geometric parameters of the grooves but also to the micro-structure pattern. The W-shaped pattern was superior to the V-shaped pattern in terms of cooling and chip removal. Grinding wheel A and grinding wheel B had similar abrasion resistance, which were 26% less and 23% less than the abrasion resistance of grinding wheel C, respectively. [ABSTRACT FROM AUTHOR]

Coarse-grained bronze-bonded diamond grinding wheels dressed using lasers and silicon carbide dressing wheels were used to grind YG8-cemented carbide workpieces. The wear patterns and grinding ratios of the laser-dressed grinding wheels were investigated after different grinding stages. After grinding, the laser-dressed grinding wheel displayed superior surface topography compared to the silicon carbide wheel, and the surface quality of the workpiece also improved. The minimum surface roughness of the workpiece was 0.425 μm. In the initial wear regime, the primary mechanisms included abrasive wear and grain removal. The grinding ratio was approximately 205.4, and the surface roughness of the workpiece after grinding was 0.314 μm. In the steady-state wear regime, abrasive wear was the primary mechanism of wearing, while minor amounts of grain removal and bond wear were observed. The grinding ratio was approximately 405.1, and the surface roughness was 0.337 μm. In the accelerated wear regime, the primary mechanisms were grain removal, abrasive wear, and bond wear. The grinding ratio was approximately 96.0, and the surface roughness was 0.454 μm. [ABSTRACT FROM AUTHOR]

A triangulation-based closed-loop control system with high-precision couple charged device (CCD) laser displacement sensors was used to true and dress a bronze-bonded diamond grinding wheel online with an acousto-optic Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser. The microscopic surface topography of the trued and dressed grinding wheel was observed using a three-dimensional (3D) microscope with an ultra-large depth of field. The results showed that the diamond abrasives were uniformly distributed on and protruded from the surface of the bronze bond, which indicated good topography of the grinding wheel. Orthogonal grinding experiments were conducted on the laser-dressed bronze-bonded diamond wheel, and three quality evaluation indices, the grinding ratio, the grinding force ratio, and the workpiece surface roughness, were measured and calculated. The results of the grinding experiment were systematically analyzed using a gray relational analysis. Under the experimental conditions of this study, the dominant factor that affected the quality evaluation indices was the laser spot diameter, followed by the pulse duration. The laser power was a secondary factor. [ABSTRACT FROM AUTHOR]

A novel online tangential laser profiling method was developed in this study. The system consisted of a pulsed fiber laser, a surface grinder, a motorized three-dimensional (3D) translation stage, laser displacement sensors and a laser power meter. Online tangential laser profiling was conducted on coarse-grained (120) bronze-bonded diamond wheels. When the laser power exceeded 40 W, the laser beam simultaneously removed the diamond grains and the bronze bond to produce a smooth wheel surface. The mean circular runout error and the axial gradient error of the grinding wheel surface decreased from 203.4 and 67.6 μm to 9.5 and 0.8 μm, respectively, indicating that the wheel contour accuracy improved significantly after profiling. The diamond grains on the grinding wheel surface were graphitized during laser profiling. However, blowing a protective argon (Ar) stream or spraying water mist from the side during profiling decreased the extent of graphitization compared to that in air. [ABSTRACT FROM AUTHOR]

For the finishing of some difficult-to-machine materials, such as silicon carbide, diamond, and so on, a novel polishing technique named plasma-assisted polishing (PAP) was proposed, which combined with the irradiation of atmospheric pressure water vapor plasma and polishing using soft abrasives. In this article, application of PAP to 4H-SiC (0001) substrate was conducted. We used helium-based water vapor plasma to modify the mechanical and chemical properties of the SiC surface. The results of X-ray photoelectron spectroscopy measurements indicate that the surface was efficiently oxidized after plasma irradiation, and the main product was SiO. CeO was used as the abrasive material in PAP, the hardness of which was near to that of the oxidized surface. The scanning white light interferometer images of the PAP processed surface showed us that scratches disappeared and surface roughness also decreased from 4.410 nm p-v, 0.621 nm root mean square (rms) to 1.889 nm p-v, 0.280 nm rms. From the atomic force microscopy images, step and terrace structure was observed on the surface after PAP, which means an atomically flat surface was obtained. The PAP processed surface was observed using cross-sectional transmission electron microscope, which indicated that almost no crystallographical defects were introduced. [ABSTRACT FROM AUTHOR]