Analysis of some defects of valve plate of automobile gearbox in die casting production

In recent years, with the promotion of energy saving and emission reduction, light weight and environmental protection in China, more and more aluminum alloy die casting technology is used in automobile manufacturing to produce the required components, such as gearbox housing, front cover housing, gearbox valve plate and engine block. Among them, the valve body of automobile die-casting gearbox needs to play multiple functions after assembly and use, and also has more complex structure and higher internal quality requirements, so as to ensure that the automobile can have good transmission capacity after carrying the valve body, which brings great challenges to the design of die-casting production.

Combined with the processing of die casting aluminum alloy valve plate of automobile gearbox produced by ZHY casting, how to effectively improve the original casting when there are defects in production is discussed. The casting is an important structural support part and shell protection part of automobile gearbox. The material is ADC12 and the overall dimension is 425mm × 180mm, the maximum wall thickness is 8.7mm, the blank weight is 2.3kg, and the overall structure of the component is large.

In the process of die casting, the liquid aluminum is first modulated under the condition of ultra-high pressure and high temperature, and then quickly transferred into the filling mold under the action of pressure. In this process, gas is easily mixed in the process of liquid aluminum transfer. In order to ensure that the casting can play its special purpose, it is necessary to do a good job of air tightness inspection to avoid air mixing affecting the mechanical properties of the casting.

The relevant manufacturing standards also stipulate that the die casting aluminum alloy castings should have compact structure, internal and external pores should meet the strict requirements of relevant specifications, and there should be no other casting defects that affect the performance. The valve plate of gearbox is a typical complex die-casting aluminum alloy component because of its complex structure, irregular structure and large wall thickness variation.