Fengkui Cui

A Model of Surface Residual Stress Distribution of Cold Rolling Spline

Residual stress is an important parameter in the evaluation of the performance of a cold rolling spline surface. However, research on cold rolling spline is rare. To improve the surface property of a spline, an involute spline is selected as the object of this study. The contour method for determining cold roll-beating residual stress involves measuring the force spatial distribution, performing a statistical analysis of the experimental results, establishing the parameters for the tooth profile for different positions (dedendum, pitch, and addendum) of residual stress, and determining the effect of pressure on the relationship between stress and the depth of the cold roll-beating. A response surface method is used to establish the spline tooth profile of the dedendum, pitch, and addendum of the residual stress and different depths of the stress layer to obtain the parameters of a multiple regression model and perform a comparative analysis of the experimental and prediction results. Research indicates that the prediction results have high reliability. The establishment of this model has important guiding significance to control the residual stress in the cold roll-beating forming process, optimize the cold roll-beating processing parameters, and improve the surface properties of cold rolling spline.

Optimization of the Physical and Mechanical Properties of a Spline Surface Fabricated by High-Speed Cold Roll Beating Based on Taguchi Theory

The aim of this work is to control the physical and mechanical properties of a spline surface and achieve a reasonable choice of high-speed cold roll-beating processing parameters. The surface residual stress and surface work hardening at the indexing circle serve as the main evaluation indices of the physical and mechanical properties of the spline surface. The influence degree of the processing parameters on each evaluation index is analyzed using Taguchi theory. An optimized model for improving the Taguchi process capability index that combines Taguchi theory with entropy theory is established, and the integral process capacity index is optimized via the generalized price reduction gradient method. The results of the optimization and the verification test are implemented in a high-speed cold roll forming test for comparison. The results show that the influence of processing parameters on the physical and mechanical properties of the splash surface of the cold roll can be ordered as follows: feed rate > roll round radius > cold roll-beating speed. In addition, the spline surface physical and mechanical properties of the optimal processing parameters were obtained for the combination of a cold rolling speed of 1581u2009r/mm, feed rate of 42u2009mm/min, and roll round radius of 2u2009mm.

Surface Performance Multiobjective Decision of a Cold Roll-Beating Spline with the Entropy Weight Ideal Point Method

Surface performance is an important indicator of the performance of cold roll-beating spline processing. To obtain the best cold roll spline surface performance (surface roughness, residual stress, and surface hardening degree), multiobjective optimal process parameters must be determined. To this end, this paper takes the cold roll-beating spline as the object of study and carries out a cold roll-beating spline surface performance test study. An ideal algorithm for entropy weight is constructed, and the multiobjective decision of the cold roll-beating spline surface performance is determined by using the entropy weight ideal point algorithm, providing a decision on the cold roll-beating spline processing parameters. The grey correlation algorithm is used for verification, and the results show that the multiobjective decision of the cold roll-beating spline surface performance is feasible by using the constructed entropy weight ideal point algorithm.

Study on Microstructure Evolution during the Cold Roll-Beating of 40Cr

For revealing the forming mechanism in micro level and for establishing the relationship between macroscopic deformation and microscopic changes, impact experiment of material property is conducted under the high speed cold roll-beating condition based on the plastic deformation mechanism of metal material, Based on the Zener-Hollomon constitutive relation, the macro change model is established, and the parameters of the 40 Cr are obtained according to the experimental data. Based on the model of microstructure evolution of dislocation density, the relation between macroscopic change and microscopic change is established, which provides the theoretical support for the forming process in micro level and revels the relationship between macro deformation and micro changes in the forming process of high speed cold roll-beating.

Gray Relational Optimization of the Surface Performance of Splines Formed by Cold Roll-Beating

Surface roughness, residual stress, and work hardening are the key parameters characterizing the mechanical properties of a spline surface after undergoing cold roll-beating. A comprehensive optimization of the mechanical properties of such surfaces has not been previously reported. To improve the performance of the spline surface, gray theory is used to study the relationships between the surface roughness, residual stress, and work hardening in the pitch diameter of spline teeth. This method addresses the surface performance optimization of an involute spline as influenced by the cold roll-beating speed and feed rate as the main parameters during the cold roll-beating process. The results show that the surface roughness and hardening degree of the splines increase with an increasing feed rate but decrease with an increasing cold roll-beating speed; the residual stress of the spline decreases with an increasing feed rate and increases with an increasing cold roll-beating speed. The results also show that the feed rate has a strong influence on the surface performance of splines produced by cold roll-beating. The optimal process parameters in terms of the spline surface performance are a cold roll-beating speed of 1428 r/min and a feed rate of 42 mm/min. The results of the present work emphasize the significance of improving the surface performance of the cold roll-beating spline-forming process and determining the optimal process parameters.

Surface work-hardening optimization of cold roll-beating splines based on an improved double-response surface-satisfaction function method

The work hardening of a spline during cold roll-beating is used as an indicator to evaluate the mechanical properties of the surface. To further optimize the work-hardening degree of a cold roll-beating spline surface, weight theory and satisfaction functions are used to improve the double-response surface-satisfaction function model. The model describes the involute spline based on the cold roll-beating speed and feed rate. The generalized reduced-order gradient method is applied to optimize the optimal combination of processing parameters. The experiments validate the optimization results of the improved double-response surface-satisfaction function method and the conventional response surface method based on the cold roll-beating spline test and a comparative analysis of the spline surface metallographic structure. The results show that the satisfaction degree of the improved response model is 0.87384, indicating that the model is robust and reliable. The optimized processing parameters are a cold roll speed of 1448.21u2009r/mm, a feed rate of 41.71u2009mm/min, and a degree of work hardening of 144.79%. The spline surface work-hardening degree based on the revised model is higher than that of the conventional model. Thus, the improved double-response surface-satisfaction function model provides better accuracy.

Analysis of Metal Flow Behavior and Residual Stress Formation of Complex Functional Profiles under High-Speed Cold Roll-Beating

To obtain a good surface layer performance of the complex functional profile during the high-speed cold roll-beating forming process, this paper analyzed the metal plastic flow and residual stress-formed mechanism by using a theoretical model of the metal flow and residual stress generation. By using simulation software, the cold roll-beating forming process of a spline shaft was simulated and analyzed. The metal flow and residual stress formation law in the motion were researched. In a practical experiment, the changes in the grains in the spline tooth profile section and the residual stress distribution on the tooth profile were studied. A microcorrespondence relationship was established between the metal plastic flow and the residual stress generation. The conclusions indicate that the rate at which the metal flow decreases changes gradually at different metal layers. The residual stress value is directly related to the plastic flow difference. As the roll-beating speed increases, the uneven degree of plastic deformation at the workpiece surface increases, and the residual stress in the tooth profile is generally greater. At the same roll-beating speed, the rate change trend of the metal flow decreases gradually from the surface to the inner layer and from the dedendum to the addendum. The residual stress distribution on the surface of the tooth profile decreases from the dedendum to the addendum. These findings provide a basis and guidance for the controlled use of residual stress, obtaining better surface layer quality in the high-speed cold roll-beating process of the complex functional profile.

Study on Thickness Thinning Ratio of the Forming Parts in Single Point Incremental Forming Process

An excessive thickness-reducing ratio of the deformation zone in single point incremental forming of the metal sheet process has an important influence on the forming limit. Prediction of the deformation zone thickness is an important approach to control the thinning ratio. Taking the 1060 aluminum as the research object, the principle of thickness deformation in the single point incremental forming process was analyzed; the finite element model was established using ABAQUS. A formula with high accuracy to predict the deformation zone thickness was fitted with the simulation results, and the influences of process parameters, such as tool diameter, step down, feeding speed, sheet thickness, and forming angle, on thinning ratio were analyzed. The accuracy of the finite element simulation was verified by experiment. A method to control the thinning rate by changing the forming trajectory was proposed. The results showed that the obtained value by using the fitted formula is closer to the experimental results than that obtained by the sine theorem. The thinning rate of the deformation zone increases with the increase of tool diameter, forming angle, and sheet thickness and decreases with the increase of step down, while the feeding speed had no significant effect on the thinning ratio. The most important factor of the thinning ratio is the forming angle, and the thinning ratio can be effectively reduced by using the forming trajectory with a uniformly distributed pressing point.

The Development Trend of Industrial Wireless Positioning Range

With the improvement of ranging precision, rangefinder has been widely used in industry development. In order to better understand the rangefinder and improve its accuracy. First, we compares the three kinds of rangefinder for advantages and disadvantages, introduces the principle and advantage of the wireless positioning range. Second, this paper briefly describes the research status of related literature at the two aspects of domestic and foreign. Third we compared the advantages and disadvantages of several signal characteristic value, and proposed the new ranging method by radio wavelength. Finally, the industrial wireless positioning technology of the future development trend is forecasted. To improve the ranging accuracy has certain theoretical significance and engineering application value, lay a foundation for the development of industrial wireless range

Research on Process Parameters of Ballscrew Manufactured by Cold Rolling

To optimize the process parameters of cold rolling the finite element model of metal plastic flow in cold rolling was carried out based on the cold forming principle of ballscrew and rigid-plastic finite element theory. The adaptive mesh refinement was utilized to improve calculation accuracy in large plastic deformation zone. Using lagrangian algorithm the processing of cold rolling is numerically simulated by DEFORM-3D. The appropriate revolution speed is got by analyzing different simulation results such as the maximum stress and maximum strain and flow velocity etc. under different revolution speeds. The appropriate transmission ratio is got by analyzing different simulation results such as the maximum stress and maximum strain and flow velocity etc. under different transmission ratios. The research results provide evidence for process parameters optimization. At the same time those research results lay a foundation of further study of forming mechanism.