商用车制动盘机械粘砂缺陷的分析及对策

根据商用车制动盘铸件粘砂缺陷废品所占比例及分布规律,结合所使用的造型线工艺特点和产品结构特点进行初步分析。为准确判断严重粘砂缺陷的产生原因,制取粘砂缺陷试样,采用金相显微镜、扫描电镜等进一步准确分析,发现总高度较高的商用车制动盘在原有工艺条件下产生的粘砂缺陷类型为机械粘砂缺陷,主要原因为砂型充填不紧实、型腔排气不畅及铁液静/动压力过大。最后,通过模拟分析,提出了简单有效的解决对策,将铸件的大部分置于上箱,并采用底注式浇注工艺,使机械粘砂缺陷废品得到彻底消除。

Analysis and Countermeasure of Mechanical Sanding Burning Defects of Commercial Vehicle Brake Discs

According to the proportion and distribution of the scraps caused by sand burning defects of commercial vehicle brake disc castings,the preliminary analysis was carried out according to the process characteristics and product structure characteristics of the molding line used.In order to accurately determine the cause of serious sand burning defects,the samples with sand burned defects were prepared,and further accurate analysis was carried out by metallographic microscope and scanning electron microscope.It was found that the on brake discs of commercial vehicle brake discs with higher total height were produced under the original process conditions,the defect type was mechanical sanding defect.The main reason was that the sand type filling was not tight,the cavity exhaustion was not smooth,and the static/dynamic pressure of the molten iron was too large.Finally,through simulation analysis,a simple and effective solution was proposed.Most of the castings were placed in the upper box,and the bottom-injection casting process was adopted to completely eliminate the mechanical sanding defect waste.