A Study on the Cooling Performance of Newly Developed Slice Die in the Hot Press Forming Process

Abstract

The cooling performance of a slice die is studied numerically and experimentally. The slice die is designed to improve the cooling performance compared to that of a conventional die that is generally used in the Hot Press Forming (HPF) process by modifying the cooling channel layout and arrangement. In order to understand the physical phenomenon of the slice die cooling performance, the cooling performance of the conventional die is also simulated and their results are compared with the slice die results. From the results of the maximum temperature of the blank and die and the temperature distribution of the blank, the slice die has considerably improved cooling performance. To validate the simulation results, the slice die is prototyped and a blank is produced by the HPF process. Blank temperatures are measured by a thermal imaging camera at several holding times. The simulation and experimental results of the blank temperatures are compared and agree with the error rate of 3%. In order to verify the quality of the produced blank, ultimate tensile stress, yield stress, and elongation tests are conducted for specimens that are extracted from the blank and are compared with existing literature results.

A Quick Cycle Time Sensitivity Analysis of Boron Steel Hot Stamping

“…The design and efficiency of the cooling channels depend mainly on the channel diameter (∅), distance from the cooling channels to the tool surface (s), and distance between the channels (d) [1,2,4,5]. Thus, designing the maximum possible cooling channels for relatively thick parts is a good solution in terms of cooling, but increases the cost of the tool.…”

“…The current industrial investment applied to the improvement of this process factor has been documented in numerous published works focused on cooling strategies and contact heat transfer improvement. Recent developments in enhanced conformal cooling strategies involve, among others, additive manufacturing of cooling channels [3], their geometrical optimization [4], and the use of alternative die manufacturing processes to improve channel positioning [5]. Studies considering the heat exchange rate associated with the contact between the die and steel sheet may be classified as experimental [6][7][8][9] and theoretical [10,11] approaches.…”

Minimisation of Heating Time for Full Hardening in Hot Stamping Using Direct Resistance Heating

“…Zhao et al [22] showed high hardness and minimum springback of a hot-stamped part by using rapid cooling to a forming temperature between 700 and 750 • C after ejecting from the furnace. Lee et al [23] designed a slice die to improve the cooling rate of the blank during hot stamping and the quenching process.…”