Cold Roll-beating Research Articles

Simulation Research on the Control Method of Bow-Collapse in Gear Cold Roll-Beating

Bow-collapse is a type of geometric defect in the gear cold roll-beating process. In order to effectively control bow-collapse and improve material utilization, this paper calculates the cross-section radius of the blank according to the volume invariance principle of metal plastic deformation, and then performs FE simulation of the cold roll-beating process by using the cyclic beating of adjacent tooth spaces and intermittent blank feeding method. The flow state of metal particles is investigated, revealing that the movement of metal particles along the axial direction of the blank is the main reason for the formation of bow-collapse. This paper proposes a method to correct the cross-section radius of the blank and thus control for bow-collapse, where the loss coefficient K characterizes the state of metal particle loss in an infinitesimal thickness region on the cross-section. The analytical equation for calculating the corrected value of the cross-section radius is derived, and the corrected value is calculated. Conducted on the modified blank, cold roll-beating FE simulation results show that bow-collapse is effectively controlled, and the loss coefficient K correctly reflects the loss state of metal particles on the cross-section. The simulation results also show that after cold roll-beating, the gear teeth with standard face width and tooth depth can be obtained after two turning end faces and turning tip circle processes. The bow-collapse control method proposed in this paper effectively improves material utilization.

Research on an Analytical Method for the Forming Force of External Spline Cold Roll-Beating

Research on an Analytical Method for the Forming Force of External Spline Cold Roll-Beating

Metal flowing mechanism of high-speed cold roll beating of spline

Metal flowing mechanism of high-speed cold roll beating of spline

Experiment Study on Hardening Behavior of Slab Cold Roll-Beating Forming

New production technologies have been developed over these last few years as answers in response to new market needs, such as higher production flexibility, lower volume batches, more complex shapes for final pieces and new materials. Cold roll-beating is an advanced precision plastic forming technology to better meet the current requirements. To investigate a material’s behavior in cold roll-beating forming operations, in this paper the principal of slab cold roll-beating was briefly introduced and slab cold roll-beating experiments were carried out, and results of the analysis conducted on the produced pieces in terms of metallographic structure and hardness distributions were reported. Our results show that the cold roll-beating forming can cause the metal surface to harden while improving the mechanical properties of the material, which is interesting in order to understand a material’s behavior when it is subjected to this peculiar deformation process; furthermore, it is of great guiding significance for further applications of the new forming technology.

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.

High-speed Cold Roll Forming Roll Rolling Thermal Coupling Friction Simulation Analysis

In order to reveal the impact of the rolling thermal coupling friction on the cold roll-beating during high speedcold roll-beating forming process, involute spline as the research object, established a high-speed cold roll-beating finite element model, the changes of elasto-plastic deformation and thermo-mechanical coupling stress during involute spline cold roll-beating contact are studied; and the distribution of temperature, stress and strain field under a single stroke; the stress, strain and temperature curves of the key elements are extracted, and the influence of temperature on the thermal coupling stress and strain is analyzed. The results show: in the process of cold roll-beating, the gradient distribution of strain field, temperature field and stress field in the area of severe deformation is very large, while the temperature, stress and strain of other small deformation areas are low; high strain and high temperature are mainly distributed in the direct contact with the rolling wheel surface area; the temperature generated during cold roll-beating reduces stress and increases the effectiveness of metal flow.

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 1448.21 r/mm, a feed rate of 41.71 mm/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.

Forming Mechanism of High‐Speed Cold Roll Beating of Spline Tooth

The spline tooth of ASTM 1045 was fabricated by high‐speed cold roll‐beating (HSCRB) process at room temperature. Microhardness of the spline tooth was examined by a nanoindenter. The grains and misorientation angle distributions were measured by electron backscatter diffraction (EBSD). The results showed that the microhardness was improved up to 1280 μm deep from the surface of the spine tooth. The microhardness and the grain sizes gradually decreased in the direction away from the surface. On the surface, the fraction of ultrafine grains increased up to about 90%, and the average grain diameter (which was ∼0.56 µm) decreased by 71.4%. The model of grain evolution during HSCRB process is proposed in this work. New grains appear first on the boundaries of the elongated grains within numerous subgrains. The elongated grains are refined as a result of subgrain rotation. By analyzing the HSCRB technical principle, we concluded that the process parameters affect the refinement degree of studied steel by determining beating pass, beating pass interval time, and strain rate.

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.

The Effect of Different Roll-beating Methodson Deformation Forces of Rack Cold Roll-beating

Cold roll-beating forming of screw is a new technology of near-net plastic forming which, by adopting high-speed revolving rolling wheels to beat the workpiece surface repeatedly and interruptedly, realizes dynamic impact, partial load and accumulation. During the forming process, the deformation force exerts great influence on the quality of the shaped component, the design of forming equipment and its service life. Based on the basic principles of cold roll-beating forming of screw, this study adopts ABAQUS software to set up a finite element simulated model of cold roll-beating forming of screw. Then the changes of the deformation force during the forming process of forward and backward beating are analyzed according to the simulation results. Rack rolling experiment is conducted on the refitted cold roll-beating forming equipment, during which the deformation force in the stable stage of the forming process is measured, achieving an identical result as the simulating result. Therefore the validity of the finite element simulation is proved, providing a reference for the choice of different ways of rolling in cold roll-beating forming.

Constitutive model of cold roll-beating forming of 40Cr

An impact experiment was conducted under high-speed cold roll-beating conditions, appropriate for the deformation mechanism of the metal material, including the effects of the deformation temperature, strain rate and dislocation density on the rheological stress in the deformation was studied in order to reveal the forming mechanism that occurs during the high-speed cold roll-beating of 40Cr. Based on the Zener–Hollomon constitutive relation, the experimental data with the parameters of the 40Cr obtained under the high-speed and large-deformation conditions, which is a material evolution model established to determine the initial stress and peak stress. Furthermore, the relationship between the macroscopic deformation and forming factors was revealed, which provided a macroscopic theoretical foundation for explaining the cold roll-beating process.

Scale-like texture defect of slab metal cold roll-beating

To optimally select the technology parameters of cold roll-beating to decrease flaws and increase the quality of the finished parts, the common flaw of scale-like texture in cold roll-beating is studied. The principle of slab cold roll-beating forming is discussed. The factors affecting slab cold roll-beating and scale-like texture flaw occurring are analysed. Theoretical analysis of scale-like texture flaw is carried out, and expression of a relation between the characterisation parameters (vertical corrugated roughness and scale-like texture flaw interval) of scale-like texture flaw and related technology parameters is obtained. Effects of technology parameters such as feed and rotating speed of the roller on vertical corrugated roughness of the scale-like texture is analysed. Forming experiments are carried out with self-developed cold roll-beating experimental equipment, and the height of scale-like texture flaw is measured to verify the correctness of theoretical analysis.

Analysis of coupled thermal–mechanical mechanism based on work hardening phenomenon in high-speed cold roll-beating

Aiming to improve the quality of part surfaces in cold roll-beating, the movement of the roller during the process was analysed. The relationships between the relative positions of the roller and the workpiece were determined. A finite element model was established for cold roll-beating simulation, which was based on the thermal effects under different roller speeds. Based on the simulation results, the change in equivalent stress resulting from the thermal–mechanical mechanism was analysed, and its influence on work hardening was determined. The theoretical basis for the control of the influence of coupled thermal–mechanical mechanism on work hardening was derived to ensure high-quality part surfaces during cold roll-beating.

Simulation Analysis of Metal Flow in High-Speed Cold Roll-Beating

In order to achieve the metal flow law in high-speed cold roll-beating, the metal flow state was analyzed on the basis of the principle of high-speed cold roll-beating and the Law of Minimum Resistance. The finite element analysis model was established based on the processing of involute spline; high-speed cold rolling forming process was simulated. The equivalent strain and the flow track of a set of nodes on the contact surface on different time are analyzed, the flow law of each node is given, and simulation analysis result is compared with theoretical analysis result.

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.

Metal flowing of involute spline cold roll-beating forming

The present research on involute spline cold roll-beating forming is mainly about the principles and motion relations of cold roll-beating, the theory of roller design, and the stress and strain field analysis of cold roll-beating, etc. However, the research on law of metal flow in the forming process of involute spline cold roll-beating is rare. According to the principle of involute spline cold roll-beating, the contact model between the rollers and the spline shaft blank in the process of cold roll-beating forming is established, and the theoretical analysis of metal flow in the cold roll-beating deforming region is proceeded. A finite element model of the spline cold roll-beating process is established, the formation mechanism of the involute spline tooth profile in cold roll-beating forming process is studied, and the node flow tracks of the deformation area are analyzed. The experimental research on the metal flow of cold roll-beating spline is conducted, and the metallographic structure variation, grain characteristics and metal flow line of the different tooth profile area are analyzed. The experimental results show that the particle flow directions of the deformable bodies in cold roll-beating deformation area are determined by the minimum moving resistance. There are five types of metal flow rules of the deforming region in the process of cold roll-beating forming. The characteristics of involute spline cold roll-beating forming are given, and the forming mechanism of involute spline cold roll-beating is revealed. This paper researches the law of metal flow in the forming process of involute spline cold roll-beating, which provides theoretical supports for solving the tooth profile forming quality problem.

Shaping Parameter Control of High-Speed Cold Roll-Beating Based on Simulation and Regression Analysis

High-speed cold roll-beating is a near-net shaping technology in which with the characteristic of metal plastic forming used, revolving roller with high speed is applied to roll and beat the blank shaft, then force mental to flow and form a component profile. In the forming process, matching between the process parameters and the part profile is key to implement and apply the technology. In this paper, the FEM model of the lead screw cold roll-beating forming is built, the ABAQUS software is used to simulate the forming process. Based on the simulation results, the orthogonal test is designed, influence of process parameters on groove depth and bulging height of cold roll-beating process are studied; multivariate regression models of maximum bulging height and groove depth relative to the process parameters are established, and the effectiveness of the models are verified, which is of important guiding significances for forming accurate profile of lead screw by controlling process parameters.

Deformation Force Simulation of Lead Screw Cold Roll-beating

Lead-screw cold roll-beating is a new type of green near-shape plastic forming technology. The deformation force is of great importance, which not only can affect the strain & stress of the material but can provide important base for equipment design, verifying tool strength and making reasonable process. This paper focuses on preliminary study of deformation force based on simulation. Firstly, the principle of lead screw cold roll-beating is simply introduced, then the FEM mode in ABAQUS is built, then the normal stress, and tangential stress simulation of lead screw cold roll-beating is carried out, finally changes of the deformation force and its component-force to time are obtained, which can provide good basis for further study.

Analysis of Lead Screw High-Speed Roll-Beating Forming

Lead screw high-speed cold roll-beating is a new single-point incremental forming technology which is die-free and unconstrained. The principle of the forming process is analyzed. Modeling, meshing and parameter selecting for forming process simulation with ABAQUS are discussed. The lead screw cold roll-beating forming process simulation is carried out; stress & strain changes and metal flowing law are analyzed. Experiments are carried out with the self-developed experimental equipment. The experimental results are consistent with the simulation results, thus the validity of the simulation and feasibility of the forming process are verified.

Simulation Study on the High-Speed Single-Point Accumulation Forming Process of Involute Spline

The high-speed cold roll-beating technology is adopted to realize the single-point accumulation forming of involute spline. Firstly, the principle of the forming technology is analyzed. Then the FEA model of the cold roll-beating of involute spline is built, the forming process simulation is finished with the ANSYS/LS-DYNA software to obtain the stress, strain and the metal flowing law of the forming process. Finally the experiments are carried out to verify the feasibility of the simulative results. This study can provide guidance for further study of the forming mechanism and practical application of the single-point accumulation forming technology.