The instrument core bracket is the key support part of the PCB board of the wave soldering equipment control system. The product diagram is shown in Figure 1. The maximum size of the product is 206.85mm x 126.80 mm x 8.60 mm, the average thickness of the plastic part is 1.20 mm, the material of the plastic part is ABS+PC, the shrinkage rate is 1.004, and the quality of the plastic part is 6.28 grams. The technical requirement for plastic parts is that there must be no defects such as peaks, injection dissatisfaction, flow lines, pores, warpage deformation, silver streaks, cold materials, jet lines, bubbles, etc.
It can be seen from Figure 1 that the plastic part is shaped as a flat bracket. The main glue positions are all connected by narrow strips. The plastic parts are thin and the plastic fluidity is poor. Plastic parts do not have various inverted buckles, and there is no need to design slider cores and inclined tops. The difficulty of mold design is the design of the gating system and the design of the ejection system. There are also many difficulties in mold processing.
Before mold design, product analysis of plastic parts is required. According to the product structure, determine the type of mold design structure. The glue position of the instrument core bracket is narrow and the melting plastic process is longer. This kind of plastic part must be designed as a three-plate mold with a fine nozzle, and more glue is injected. The hot runner can also be designed to feed glue. If a two-plate mold is designed and the side gate is filled with glue, the plastic part cannot be filled, resulting in failure of the mold design.
3D Design of Injection Mold for Instrument Movement BracketPlastic parts have poor rigidity and are easy to deform. The material selection ABS+PC, commonly known as plastic alloy, is to enhance the rigidity and strength of the plastic parts.
First of all, make sure that you must use a point gate to enter the glue. Secondly, there are several problems with glue. The development and application of injection mold CAD/CAE technology has greatly reduced the cost of mold design and processing, and has doubled the efficiency. Among them, the application of Moldflow software is the most representative. It can not only simulate and analyze the flow process of thermoplastic melt entering the mold, but also simulate and analyze the gate position, pressure distribution, cooling process and injection molding process conditions of the injection molded part, find out possible defects, and improve the first test. The success rate of the model. Reduce production costs and shorten the production cycle. The gate is a short passage connecting the runner and the cavity, and is a key part of the gating system. Plays the role of adjusting and controlling the speed of material flow, replenishing time and preventing backflow. Gate design has a great influence on the molding quality of injection molded parts. It mainly includes the design of the shape, number, size and feeding position of the gate. On the one hand, the gate design must ensure a fast, uniform, and balanced single-directional flow filling mode; on the other hand, it must avoid the occurrence of jetting, stagnation, and depression. At present, the number and location of gates are generally selected based on experience, and the design is often unreasonable, and the flow balance in the cavity cannot be guaranteed. Using injection molding CAE software for flow analysis, it is easy to predict the influence of different gate numbers and positions on the flow balance, and then make corresponding trade-offs and design changes based on the analysis results.
Through the simulation analysis of the entire injection molding, and the flow analysis of filling time, injection pressure and cooling analysis, the best gate plan for the injection mold of the instrument movement bracket is determined. Because the structure of the plastic part of the instrument movement bracket is relatively complex, in order to make the fluid have better flow performance during injection molding, it is necessary to design 6 point gates, as shown in Figure 5.
The mold design cavity ranking is 1 out 2. The mold base is the standard mold base DCI3550. The production batch of plastic parts is large. Two sets of molds are designed and produced respectively, 1 out of 1 and 1 out of 2, respectively, and the attached file is 1 out of 3D. 1. For reference only for analyzing the structure of plastic parts. Plastic parts are large in size and thin in structural strength. Mold design needs to pay attention to ejection balance. The ejector components are thimble and cylinder. When making the mold, it is necessary to pay attention to the length of the thimble to ensure that each thimble moves at the same time to prevent the plastic part from being ejected and deformed.
When making the mold, it is necessary to pay attention to the large fluctuations of the parting surface, where there is a rubbing position, cut the insert, and minimize the spark and clear corners. Electrode processing should use good copper materials to make the corners of the front and rear mold cores clear and good exhaust.
The mold is designed with a taper locator on each edge of the mold base, and the four corners of the front and rear mold cores are processed, which is conducive to accurate mold clamping.
The front and rear molds are designed for direct water transport to ensure normal injection molding.
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