Cold Extrusion Process Optimization Research On Car's Parking Ratchet Outer Teeth

For the automotive industry,how to develop high-quality,low-cost,short-cycle parts is the key to win the automotive market.The cold extrusion technology of toothed parts is widely used in the automotive industry due to its advantages of high production efficiency,excellent product performance and low manufacturing cost.When cold extrusion the toothed parts,there are problems such as insufficient filling for the teeth,large forming load and short mold life,especially for teethed parts with high tooth height and large tooth thickness.This dissertation took the parking ratchet,s outer teeth forming as the research object,establish cold extrusion process,based on the orthogonal experiment method,obtain the best process parameters,investigate the optimal design of the combined die and obtain the stress-effective distribution and wear status.Its main contents and conclusions are as follows:According to the outer teeth size and structure,using comparative analysis method,formulated outer teeth cold extrusion process specification;Based on this,designed a reasonable mold structure.Using orthogonal experiment method,put the forming load,filling degree of the teeth,collapse length and the effective tooth length as indicators.By means of Deform-3D software and Minitab software,explore the influence of the outer diameter of the blank,bottom die half angle,friction coefficient,working belt length on the outer teeth cold extrusion.The results showed that:the bottom die half angle has an greatest influence on the forming of the outer teeth,the outer diameter of the blank and the friction coefficient take the second place,the working belt length has almost no effect on the forming result.The optimal combination of process parameters was obtained and the feasibility of the parameter combination was verified.In view of the short life of the combined bottom die,calculated the size of the die theoretically,then combined with the golden section method and numerical simulation techniques.optimize the interference between the inner ring and the middle ring,the optimal value is 0.42mm,in addition,obtained the bottom die stress-effective distribution and wear conditions.After the optimization,the maximum stress-effective is 1660MPa,reduced by 29%,The wear at the edge of teeth preforming surface is the most serious,the maximum wear value is3.010?10^-6mm,the wear condition at the root of the bottom die is second and the die life is about 80000 times.Finally,took experiments on the process and the combined bottom die,it showed that:cold extrusion outer teeth matched to the simulation results completely,collapse length is less than1.1mm,effective tooth length is more than 45mm,all test results were within the scope of technical requirements.In addition,after 28000 times,the bottom die did not show cracking,tooth pre-shaped surface edge wear depth was 0.084mm,the amount of wear value was in a reasonable range.The results verified that positively cold extrusion the parking ratchet outer teeth was feasible.