Design of injection mold for the hottest circular

Design of injection mold for circular rotating shaft

1 Structure and process analysis of plastic parts

Figure 1 shows the structure diagram of plastic parts. In order to better express the structure of plastic parts, it is divided into three parts a, B and C. part a and B are two cylinders of different sizes, which play the role of rotating shaft when assembled with accessories of different sizes. Therefore, the requirements for the appearance, size and coaxiality of parts A and B are very strict, and the surface is not allowed to have segment differences, weld marks The front end of Part C is a hook that rises again and again depending on the elastic price of the plastic part itself, and inside is a cylindrical hole that gives way to the hook when assembling other accessories. A. B. inside the two parts are cross shaped stiffeners to enhance their strength. The material of plastic parts is POM, which can be produced in large quantities

Figure 1 structural drawing of plastic parts

2 design scheme of mold

according to the structural process characteristics of plastic parts, the appearance requirements of parts A and B are relatively strict. Only when they are formed in the same insert can their appearance and coaxiality requirements be guaranteed. In terms of the shape and size of the plastic part, the plastic part can only be demoulded from B to a. the maximum outer diameter is the parting surface. Part a and part B are formed on the moving mold core. In part C, except for the hook clearance hole and end face, the rest parts are formed and core pulled through the slider. Because the plastic part is small and the production capacity is large, a gate needle type point gate is used. The form of the first mock examination, four cavities and three plate mold is adopted, and the gate is selected in part A B center of internal "ten" stiffener (Figure 2). The specific design is as follows:

2.1 selection of parting surface

according to the principle of selecting the maximum projection surface of plastic parts as the parting surface, the parting surface of moving and fixed mold is selected, and the distribution of each part of moving, fixed mold and sliding block is shown in Figure 2

2.2 design of main core of moving and fixed mold

the core of fixed mold part is designed as shown in Figure 3 according to the shape of plastic parts and the selection of parting surface. In order to facilitate processing and replacement in case of damage, it is composed of stop round core with gate and main insert

Figure 3 fixed mold core

1. Stop circular core 2. Fixed mold main insert

because part C of the plastic part is formed in the slider, the design of the main mold core of the moving mold is shown in Figure 4. In order to facilitate processing, it is divided into upper and lower parts, which are positioned by positioning pins and fixed by bolts. Due to the high surface requirements of parts A and B, the shrinkage of the internal "cross" stiffener will bring shrinkage marks to the surface of the plastic part. Therefore, during the test mold repair process, increase the compensation amount of the shrinkage of the plastic part to balance the shrinkage marks of the "cross" stiffener of the plastic part, and the forming conditions cannot be adjusted casually after the repair is qualified

Figure 4 dynamic model core

1, bolt 2, 4, dynamic model core 3, locating pin 5, sealing ring

2.3 slider design

slider design is shown in Figure 5. These situations, in addition to bringing a large number of sales to the environmental experimental equipment industry, are composed of formed inserts and sliding parts, and if the eight formed inserts are found to be loose, they are installed in two sliders respectively, which not only reduces the processing cost, but also makes the assembly easier. For the appearance effect of the mold, the built-in return spring is used

Figure 5 slider design

1, insert 2, bolt 3, slider

2.4 ejection structure design

the hook yielding cylindrical hole of Part C of the plastic part is formed by a circular core. In order to make the ejection of the plastic part smooth, the sleeve ejector rod structure is adopted, as shown in Figure 6, which is composed of a push tube and a fixed circular core

Figure 6 sleeve ejector rod

1, fixed core 2, push tube

2.5 runner design

in order to make the molten plastic reach each cavity of the mold at the same time, the pouring is balanced, and the runner design is shown in Figure 7

Figure 7 runner design

3 mold structure and working process

figure 8 mold structure

1, pull rod 2, stop starting bolt since 1990s 3, fixed mold core 4, plastic part 5, moving mold core 6, slider core 7, slider 8, moving mold core 9, mold lock 10, return spring 11, water nozzle 12, bolt pull rod 13, inclined guide post 14, push tube 15, fixed mold core 16, return rod 17 Spring

figure 8 is the structure diagram of plastic injection mold. After the plastic part 4 is formed, when the mold is opened, the mold is first disposed from II - II under the action of the mold lock 9, and the runner condensate is separated from the plastic part through the pull rod 1. Then, the mold is disposed from I - I under the action of the bolt pull rod 12 and the stop bolt 2, and the runner condensate is pulled away from the main gate. Finally, the mold lock 9 opens the mold, and the mold is disposed from III - III until the moving and fixed mold are completely divided. When the moving and fixed mold is divided, the slider 7 drives the slider core 6 to move outward under the action of the return spring 10 and the inclined guide post 13, so as to separate from the plastic part. After the moving mold stops, the plastic part is ejected through the push tube 14 of the ejection mechanism. The return of the die is reset by the return lever 16 and the spring 17 on the return