制动盘脉纹原理浅析

Veining Defect Principle Analysis of the Brake Disc

针对制动盘铸件出现的脉纹缺陷问题,统计分析了不同铸件脉纹比例及分布规律,结果发现脉纹均出现在风道砂芯的上部及筋的侧面,呈扁平状的风道铸件出现脉纹几率最小。利用MAGMA模拟软件对比不同厚度砂芯温度场,结果表明浇注初期砂芯上下及内外温度差很大,同一时刻受热膨胀量不同,在芯子上部产生拉应力,当应力超过砂芯强度时产生开裂。另外,试验表明浇注静压力越高,铸件脉纹倾向越大。说明在较高的铁水静压力作用下,共晶铁水渗入到砂芯裂缝中产生脉纹。认为降低砂芯温度差,是解决铸件脉纹问题的有效途径。

In orderto analyze the form ation m echanism ofveining defectin brake disc casting,the proportion and distribution ofveining in differentstructure brake disc castings were analyzed.Itwas found thatallofthe veining defects appeared on the upperpartofcore oratthe side ofthe reinforcingtrib,and few in the castings with flatcore.MAGMA sim ulation software was used to com pare the tem perature field ofsand cores with differentthickness.The results showed thatthere was large tem perature difference between the top and bottom,centerand exteriorpartofthe core.So the tensile stress was created atthe top core.W hen the force exceeded the strength ofcore,the sand core cracked and the eutectic liquid m etalentered the crack.The higherthe pouring static pressure,the greaterthe veining tendency.R educing the tem perature difference ofthe core isan effective way to elim inate veining defect.