Research on the profile modification of power skiving tool for internal gears

Power skiving provides an effective solution and considerable machining efficiency for the machining of internal gears. The tool profile design and the reusability after resharpening is critical in gear machining. In this paper, a tool profile correction method based on the error inverse complement of involute profile is proposed. The mathematical model of involute cutter with rake angle and relief angle is established, and the profile error relative to the target gear is calculated by using the tool of this mathematical model. The distribution of gear profile error is fitted by fifth-order multinomial, and the multinomial function of fitting was attached to the cutter profile. The theoretical error of the target gear profile is in 10e-7mm order of magnitude through the calculation of fewer iterations. The distribution of the coefficient of the error multinomial along the resharpening direction is obtained by linear programming. The result shows that the tool designed by this method has almost negligible error accuracy and good repeatability.

Tool profile stationarity while simulating surface plastic deformation by rolling as a process of flat periodically reproducible deformation

Introduction. Surface plastic deformation is an effective way to improve the operating performance of machine parts. One of the promising approaches to the design of surface hardening technological processes is the technological inheritance mechanics. To calculate the hereditary parameters characterizing the accumulated deformation and damage to the metal, it is possible to simulate spinning as a process of plane fractional deformation, which significantly reduces the time required for modeling the process. However, upon rotation of the plane in which the stress-strain state is considered, the roller profile changes. The aim of the work is to assess the magnitude of the change in the roller profile in the deformation plane during deformation as an important factor ensuring the accuracy of the solution obtained. Research methods. The roll profile in the warp plane is defined by the intersection line of the roll surface and this plane. The paper presents the procedure for calculating the coordinates of the points of intersection lines, which are curves of the fourth order, depending on the geometric dimensions of the roller and the part, as well as the angle of inclination of the deformation plane. Results and discussion. To estimate the value of the roller profile change, the coordinates of the points of the intersection lines of the roller surface and the deformation plane are determined for the rolling modes corresponding to a sufficiently developed plastic deformation, the obtained lines are approximated in the coordinate system associated with the deformation plane, and the relative change in the coordinates of the intersection lines when the plane was rotated are estimated. As a result of the conducted analytical studies, it is found that even with developed plastic deformation, the relative change in the coordinates of the points of intersection lines does not exceed 0.1%. This indicates the possibility of using a stationary roller profile when simulating rolling using the plane fractional deformation model.

Influence of Tool Length and Profile Errors on the Inaccuracy of Cubic-Machining Test Results

A cubic-machining test has been proposed to evaluate the geometric errors of rotary axes in five-axis machine tools using a 3 × 3 zone area in the same plane with different tool postures. However, as only the height deviation among the machining zones is detected by evaluating the test results, the machining test results are expected to be affected by some error parameters of tool sides, such as tool length and profile errors, and there is no research investigation on how the tool side error influences the cubic-machining test accuracy. In this study, machining inaccuracies caused by tool length and tool profile errors were investigated. The machining error caused by tool length error was formulated, and an intentional tool length error was introduced in the simulations and actual machining tests. As a result, the formulated and simulated influence of tool length error agreed with the actual machining results. Moreover, it was confirmed that the difference between the simulation result and the actual machining result can be explained by the influence of the tool profile error. This indicates that the accuracy of the cubic-machining test is directly affected by tool side errors.

Tool Profile Modification of Hypoid Gear Machined by Duplex Helical Method

For the hypoid gear pair of the heavy-duty vehicle drive axle machined by the duplex helical method, in order to avoid edge contact and stress concentration on the tooth surface, a four-segment tool profile is designed to modify the concave and convex surfaces simultaneously. First, the geometric model of the four-segment tool profile is established. Second, the mathematical model of the duplex helical method based on the four-segment tool profile is established, and the method of solving the tooth surface generated by the connecting points of the four-segment tool profile is given. Finally, the finite element method of loaded tooth contact analysis is used to analyze the meshing performance of the gear pair obtained by the four-segment tool profile modification, and the results are compared with the original gear pair. The results show that after the tooth surfaces are modified, the edge contact of the tooth surfaces are avoided, the stress distribution of the tooth surfaces are improved, the maximum contact stress of the tooth surfaces are reduced, and the fatigue and wear life of the tooth surface are improved.

Understanding Size Effects and Forming Limits in the Micro-Stamping of Industrial Stainless Steel Foils

This study investigates the effect of grain size and composition on the material properties and forming limits of commercially supplied stainless steel foil for bipolar plate manufacture via tensile, stretch forming and micro-stamping trials. It is shown that in commercially supplied stainless steel the grain size can vary significantly and that ‘size effects’ can be influenced by prior steel processing and composition effects. While the forming limits in micro-stamping appear to be directly linked to the plane strain forming limits of the individual stainless steel alloys, there was a clear effect of the tensile anisotropy. In contrast to previous studies, forming severity and the likelihood of material failure did not increase with a decreasing channel profile radius. This was related to inaccuracies of the forming tool profile shape.

Fabrication of Magnesium–NiTip Composites via Friction Stir Processing: Effect of Tool Profile

In this study, a solid-state fabrication route via friction stir processing (FSP) was used to fabricate Nitinol particulate (NiTip)-reinforced magnesium-based composites to avoid the diffusion reaction and the formation of brittle interfacial compounds. The effect of four tool profiles on the homogeneity in the dispersion of NiTip particles in the magnesium matrix and microhardness was examined and analyzed. A counter-clockwise scrolled shoulder with a plain cylindrical pin and three tools with a flat shoulder having plain cylindrical pin, left-hand, and right-hand threaded pins were used and compared. The tool profiles were observed to exhibit a significant influence on the microstructure of the fabricated Mg/NiTip composites. A wider and more uniform distribution of NiTip particles along with superior bonding with magnesium matrix was achieved with a left-hand threaded cylindrical pin tool. The incorporation of NiTip gave rise to a significant increase in the microhardness of the fabricated composites due to a variety of strengthening mechanisms.