Original production process for defects of valve plate of automobile gearbox in die casting production

1. Component classification block

The structure of the valve plate of the automobile gearbox is complex and has a large tightening force. The overall structure is shown in the figure. When designing the dynamic model, the component parting blocks are divided according to the functional structure of each part.

2. Design component slider

In order to ensure the full play of the function, it is particularly necessary to pay attention to the air tightness of the sealing groove in the design to avoid the internal and external pore structure. For this reason, a number of slide blocks are used in the design and forming of the component die, so that the sealing grooves with various length and depth can be cast. In order to determine the mold cavity, it is necessary to synthesize the basic size and average tolerance of the casting, so as to obtain the average size of the casting. In addition, the influence of aluminum alloy linear shrinkage, coating thickness and thermal expansion coefficient under high temperature conditions on it is added to determine the casting mold size.

3. Design component gating system

The pouring of aluminum alloy components and other operations generally select low pressure conditions, so that the liquid metal can be filled and condensed in the mold stably and rapidly, and can buffer the influence of fluctuation, screen out the slag in the liquid metal, and the later liquid can timely fill the remaining position of the condensed liquid. In the process of processing the valve plate of automobile gearbox, the lowest point is selected for mold filling, in which the splashing phenomenon of molten aluminum is effectively controlled, and the air mixing and oxidation slag inclusion in the process are reduced. The pouring system with comb shaped design, slag collecting trough, riser and other pouring system units are used to ensure the pouring stability.

4. Design of partition layer in classified block

Each parting block of the component has higher air tightness requirements, which can’t meet the problems of inclusion, cold shut, air hole and so on. Because each block is far away from the gate, it is difficult to fill the mold with liquid aluminum, especially in the final filling part, which is prone to cold shut defects. In order to ensure the integrity and quality of the whole mold filling, several gate points are set in the mold, and a 3mm thick spacer layer is also designed near the moving die side of each block, so that the last gate can solidify at the latest and become the feeding channel of the component.