What are the reasons for the failure of the injection mold(3)


7. The fixed tensioning mechanism fails. Fixed-height t […]

7. The fixed tensioning mechanism fails. Fixed-height tensioning mechanisms such as pendulum hooks and buckles are generally used in fixed-core pulling or some secondary demoulding molds. Because these mechanisms are arranged in pairs on both sides of the mold, their actions must be synchronized, that is The mold is buckled at the same time, and the mold is released to a certain position and unhooked at the same time. Once the synchronization is lost, the template of the drawn mold will inevitably be skewed and damaged. The parts of these mechanisms must have high rigidity and abrasion resistance, and adjustment is difficult. The life of the mechanism is short. Avoid using it as much as possible and use other mechanisms. In the case of relatively small core-pulling force, spring can be used to push the fixed mold method. In the case of relatively large core-pulling force, the core can slide when the movable mold is retracted, and the structure of the core-pulling is completed after the core-pulling action is completed. The hydraulic cylinder can be used for core pulling on the mold. The oblique pin slider core pulling mechanism is damaged. The most common faults of this mechanism are that the processing is not in place and the material is too small. There are two main problems.
The oblique pin inclination angle A is large, and the advantage is that a relatively large core pulling distance can be generated in a short mold opening stroke. However, if the inclination angle A is too large, when the pulling force F is a certain value, the bending force P = F / COSA that the oblique pin receives during the core drawing process is larger, and the oblique pin deformation and oblique hole wear are likely to occur. At the same time, the oblique pin produces an upward thrust N = FTGA on the slider, which increases the positive pressure of the slider on the guide surface in the guide groove, thereby increasing the frictional resistance when the slider slides. Easy to cause sliding irregularities, guide groove wear. According to experience, the inclination angle A should not be greater than 25
8. Some molds are limited by the area of ​​the template and the length of the guide groove is too small. The slider is exposed outside the guide groove after the core pulling operation is completed. In this way, the slider is easy to tilt after the core pulling stage and the initial stage of mold clamping reset, especially in the When the mold is closed, the slider is not reset smoothly, causing damage to the slider and even bending damage. According to experience, after the slider completes the core pulling action, the length remaining in the chute should not be less than 2/3 of the total length of the guide groove.
9.Finally, when designing and manufacturing the mold, it should be based on the specific requirements of the quality of the plastic parts, the size of the batch, and the requirements of the manufacturing period, which can meet the product requirements, the most simple and reliable in the mold structure, easy to process, and low cost This is the perfect mold.