Cold draw processing technology can be applied to carbon steel, stainless steel, aluminum-magnesium alloy, and various types non ferrous alloy. The cold draw equipments are simple, low cost, and easy for maintenance. Cold drawn metal parts have the advantages including precision in size, relatively smooth surface, not necessary for subsequent processing, suitable for continuous and rapid production. The key points of the cold draw process are the design of the cold draw die and the number of pass. An efficient forming by appropriate pass distribution and die design is extremely important which would influence the quality of the cold drawn components.
In this research, cold draw forming process of medium carbon steel bars was analyzed by using numerical simulation with the software package SIMUFACT. The plastic deformation behavior, the average cold draw stress, the internal effective stress, and damage criterion at single pass and multi-pass cold draw for different cross-section shapes were studied. For different cross-section shapes, the influence of different cold draw process parameters and different die shape and number of passes on the average cold draw stress and the internal effective stress was investigated. Necking may occur on the workpiece front end where the rod is clamped and cold draw force is applied if the average cold draw stress exceeds a critical value. The critical stress was also determined.
The Lemaitre damage criterion was applied to evaluate the stress and strain conditions in the cold drawn workpieces for the possible occurrence of damage. Damage parameter was determined for the workpiece of different cross-section shapes during the multi-pass cold draw forming. The process parameters were chosen within the critical damage limit to ensure a safe cold draw process. Comparison between the simulation results and the real cold draw cases were made to validate the numerical results.