Design of Injection Mould for Jingyi Box Cover
The product diagram of the Jingyi box cover is shown in Figure 1. The maximum size of the product is 197.00 mm x 197.00 mm x 15.70 mm, the average thickness of the plastic part is 3.00mm, the material of the plastic part is ABS, the shrinkage rate is 1.006, and the quality of the plastic part is 147.20 grams. The technical requirements for 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, and jet lines.
It can be seen from Figure 1 that the plastic part is shaped as a square flat shell with a relatively simple shape. There are multiple protruding bone positions on the inner side of the week, which need to be designed with a sloped roof. There is a stop on the edge of the plastic part to match the lower shell of the precision instrument box. The appearance of plastic parts is required to be high, and there should be no gate marks and ejection marks on the top and side. According to the requirements of plastic parts, flip chip molds need to be designed. The flip die is a die with the ejector system installed on the side of the fixed die. Generally, it is ejected by an oil cylinder, but it can also be ejected with components such as a pull plate or a button. The use occasions are generally cover and shell products, and the surface requirements are relatively high and no gate marks are allowed. The structure diagram of the Jingyi box cover mold is shown in Figure 2.
The size of the plastic part is large, and the mold design cavity rank is 1 out 1. The mold base is a non-standard mold base 5050. In order to ensure the mold clamping accuracy, 0 degree positioning blocks are designed on all four sides of the mold base; front and rear mold cores The four corners are designed to locate the tiger's mouth, and the fixing method is compressed by a squeeze block. Since the ejector mechanism and the pouring system of the flip chip die are both designed on the fixed mold side, it is necessary to pay attention to the position of the pouring system and the ejector components not to interfere in the design; on the other hand, for the flip chip die, the position and quantity of its gates need to be evaluated. Try not to design a three-plate mold with a thin nozzle, because the runner condensate is difficult to take out under the surrounding sloping top and thimble. Therefore, in most cases, flip-chip molds use hot runner injection methods. This set of mold uses INCOE's single hot nozzle DFQ18150-STT, and the gate position is in the center of the plastic part. This kind of hot nozzle is a needle valve nozzle. After the injection is completed, the needle valve is closed, and there is only a circular mark on the final plastic part, which will not affect the appearance of the plastic part. The needle valve hot nozzle is shown in Figure 4.
The thickness of the plastic part is 3mm, and the glue position is thick. Therefore, in order to shorten the injection cycle and avoid the deformation of the plastic part, it is necessary to design an adequate cooling system. In order to prevent the heat of the fixed mold from being transferred to the injection molding machine, a heat shield is designed on the fixed mold base plate. The front and rear mold water transportation diagrams are shown in Figure 3. The fixed mold water transportation adopts direct water transportation, and the movable mold design direct water transportation and pond water transportation.
The plastic parts are ejected by inclined jacking and cylinder ejection. All inclined roofs are T-slot driven inclined roofs, and inclined roof guide blocks are designed on the template. Mold opening adopts pull plate to pull the mold. It should be noted that the dimensions of the four pull plates must be the same, and the positions of the pull screws must be the same to avoid stress on a single pull plate and affect the accuracy of the mold.
