A car bumper is one of the most important exterior parts of a car. It not only has sufficient strength and rigidity, but also plays a buffering role in a collision accident, protects the body, and pursues harmony with the shape of the body. To achieve these goals, current car bumpers are made of plastic, commonly known as plastic bumpers.
The shape of the front bumper of a car is similar to that of a saddle. The material is PP+EPDM-T20, and the shrinkage rate is 0.95%. Among them, PP is the main material of the bumper. EPDM can increase the flexibility of insurance coverage. T20 means adding 20% talc to increase the stiffness of the cap.
The characteristics of the car bumper shape are:
1. The shape is complex, the size is large, and the wall thickness is relatively small, which belongs to large thin-walled plastic parts.
2. K/Os, S/Os, large stiffeners, resistant to melt flow.
3. There are 3 undercuts on the inside of the car bumper, and it is difficult to pull the core out horizontally at each position.
The conclusion is:
1. Adopt internal grading technology to ensure the appearance of plastic parts.
2. The car bumper adopts the secondary core-pulling structure of "composite inclined roof", which solves the problem of lateral core-pulling of complex parts.
3. The eight-point needle valve type sequential valve hot runner gating system is adopted to solve the melt filling problem of large thin-walled plastic parts.
4. The use of hydraulic pressure as the driving force of the demoulding system solves the problem that the demoulding force of the plastic part is large and the tablet is difficult to reset.
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