热冲压成形模具冷却系统临界水流速度研究

Study on the critical water flow speed of the cooling system of hot stamp shaping mould and die

为保证热冲压过程中模具具有良好散热效果,优化超高强度钢板热冲压成形模具冷却系统设计,提出热成形模具冷却系统中的临界水流速度。采用解析法建立热冲压模具冷却系统中模具与支撑柱及水流传热模型,获得临界水速的解析公式;通过计算机数值模拟的方法,分析了冷却水流速度对模具向支撑柱和向水流传热的热流密度的影响,验证了临界水速的存在性,继而探索了临界水速下支撑柱半径对模具散热量的影响。结果表明,热冲压模具冷却系统中,水流速度达到临界水速时,模具冷却系统中支撑柱尺寸及有无支撑柱均不影响模具总散热量,即冷却系统中水流速度为临界水速时,模具设计可不考虑支撑柱尺寸的影响,从而给优化热冲压模具冷却系统设计提供了理论支持。

For the sake of ensuring mould and die to possess good heat dissipation effect in the course of hot punching, and of optimizing the cooling system design of the hot punch shaping mould and die of super high strength steel plate, the critical water flow speed in the cooling system of hot shaping mould and die was put forward. By adopting the analytical method, the heat transmission model for the mould and die, the strut and the water flow in the cooling system of hot punching mould and die was established so as to obtain the analytic formula of the critical flow＇speed. By way of the method of computer numerical simulation, influences of the speed of cooling water on the thermal current density transmitted from mould and die to the strut and the water flow were analyzed, the existence of critical flow speed was verified, and then explored the influence of strut radius under critical flow speed on the heat dissipating capacity of mould and die. The results indicated that within the cooling system of hot punching mould and die while the flow speed reaches the critical flow speed, the strut dimensions and whether the struts exist or not in the die cooling system all wouldn ＇ t affect the total amount of heat dissipation of mould and die. That is while the flow speed in the cooling system reaches a eritieal flow speed the influences of strut dimensions may not be taken into consideration in the die design, thus provided theoretical sustain to the optimization on the cooling system design of hot punching mould and die.