The product diagram of the shielding cover is shown in Figure 1. The maximum size of the product is ø85.7 mm x 55.20 mm, the average thickness of the plastic part is 1.50 mm, the material of the plastic part is HIPS, the shrinkage rate is 1.005, and the quality of the plastic part is 10.5 grams. The technical requirements of plastic parts are that there must be no defects such as peaks, dissatisfaction with injection molding, flow lines, pores, warpage deformation, silver streaks, cold materials, jet lines, and bubbles.
It can be seen from Figure 1 that the structure of the plastic part is hemispherical. There is a long hollow column in the center of the plastic part. The side of the column is open, divided into two pieces, and each has a buckle on the head for clamping during assembly. The difficulty of the mold design is the design of the demoulding method of the central column buckle. The buckle here needs to be designed with a tunnel-type slider to solve it. Another difficulty is the need to design a forced demoulding mechanism after the buckling slider is disengaged.
After careful analysis of the plastic parts, there are two core-pulling directions of the tunnel slider. See Figure 3. A and B two core-pulling design schemes, the moving direction of the slider is perpendicular to each other. Both of these two design schemes can make products, but the details are different. Details determine success or failure, and mold design must be able to observe the details and analyze and compare different results. The mold design adopts Plan A. Plan A makes the two buckles on the same slider, and the buckle part has a vertical clamping line, but there is an advantage that the two buckles are on the same slider, which can avoid the sticking of the buckle. Hold the slider and pull to deform. Scheme B designs each buckle separately on the same slider, which may cause the buckle to stick to the slider and deform.
The cavity layout of the mold design is 1 out 2. The mold base is DI3045, the gate is a horn gate, and the glue is injected from the bottom of the edge of the plastic part. The advantage of the horn gate is that it can be automatically disconnected after the mold is opened, and the position of the gate at the bottom of the edge of the plastic part will not affect the appearance. In order to ensure the accuracy of mold clamping, a zero-degree positioning block is designed on the edge of the mold embryo.
The principle of forced demolding is that the plastic part has deformation space. The second factor is the plastic material. Most thermoplastics can be forced out of the mold, provided that the plastic part has room for deformation. In the extreme case where there is no space for deformation, only a few plastics such as PP and PE can be forced to demold, but the amount of strong release must be less than 0.3. In order not to damage the product during strong release, the back mold core is designed with a slope of 40 ゜ to facilitate the release of the buckle position during strong release, as shown in Figure 4.
The column buckle must be forced off the back mold after the slider core is pulled. In order to form a deformation space for the buckle to be forced off, it is necessary to pull out the insert in the inner hole of the column first, so that the buckle can be deformed inward. After the mold is opened, the mold is first opened between the push plate and the backing plate, the push plate bounces 40, and the insert 27 is first withdrawn from the inner hole of the column. The mold is opened again, the parting surface is opened, and the latent slider completes the buckle and core pulling.
The ejector of the plastic part is ejected by a thimble. In order to make the thimble plate system return in time and accurately, a yellow rubber 14 is designed at the bottom of the needle. The ejection system adopts the method of strong tension and strong ejection. No return spring is installed on the ejector plate, and threaded holes are drilled at the KO hole of the ejector plate.
The mold cooling system is designed with two rounds of straight-through water transport on the front mold, divided into two layers with different heights, so that the cavity can be fully cooled. The cooling of the movable mold is a combination of straight-through water transportation and a pond.
The sliding block is driven by an oblique guide column, and the positioning of the sliding block adopts the tiger buckle of DME, the model is PSM-0001. This kind of sliding block positioning method is powerful and reliable, and it is widely used in American molds.
Email: Daisy@abismold.com
Phone: +86-150 1652 6799
Skype: daisymold@outlook.com
WhatsApp: +86-136 8261 9739
Tex: +86-755-8998 4896 Ext 821
Fax: +86-755-2896 0682