Process improvement of valve plate defect of automobile gearbox in die casting production

1. Set ice pack and extend setting time appropriately

Through X-ray examination and local dissection, it is found that the internal structure of the casting block hole is relatively compact, and the original structure design does not have defects such as porosity and cold shut, which means that the production system under the original design has sufficient filling capacity. Therefore, it is proposed to change the 3mm interlayer into a slag ladle with an opening at the top of the hole, which can collect the mixed gas and cooling liquid aluminum during mold filling during production. During the operation, the solidification time was extended from 270s to 350s. After adopting the scheme, the batch production is carried out, and the hole position of the release component block has good internal quality, and there is no air hole.

2. Setting extrusion pin

Considering that there are many screw holes that need to be extruded in the whole component, in order to control the space and force of the extruder and improve the efficiency, combined with the characteristics of screw hole location, a number of groups of three extrusion pins were designed ° Uniform distribution of extrusion structure, in a number of cylinder driven extrusion operation. After adopting this scheme, the cast components have good quality of screw holes, and the diameter deviation of a small part of shrinkage holes is less than 0.5%. After the improvement measures such as adding slag ladle, extending solidification time and adding extrusion pin were taken, the proportion of air hole defects in the valve plate of automobile gearbox was reduced to less than 0.5%, and the size of each air hole was reduced from 3 mm to 0.5 mm, and there was no shrinkage of screw hole, The quality of die casting components is greatly improved, and the qualified rate is increased to more than 95%.

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