Electronic switch seat of a car is an electronic control component of a Japanese brand car. Product diagram is shown in Figure 1. Maximum external dimension of product is 94.06 mm * 55.00 mm * 36.20 mm, average thickness of plastic parts is 1.26 mm, material of plastic parts is PC+ ABS, shrinkage rate is 1.005, and weight of plastic part is 16.97 grams. Technical requirements for plastic parts are that there shall be no defects such as peaks, underfilling, flow lines, pores, warpage deformation, silver lines, cold materials, and spray lines.

 

Figure 1 Product map of car electronic switch seat
As can be seen from Figure 1, appearance of electronic switch seat of car is a closed shell, and there are multiple small rectangular holes on the two long sides, which requires design of a large slider core. Edges of the two raised openings on the top of plastic part have raised undercuts on both sides for clamping during assembly. Difficulty of mold design lies in the choice of mold opening direction. According to conventional design, if two protruding openings at the top of plastic part are placed on the side of fixed mold, large sliders on both sides contain top inversion position, which will increase core pulling distance of large slider before plastic parts can be taken out. In order to shorten core-pulling distance of movable mold core-pulling, or avoid small lifter with complicated fixed mold design, plastic parts are designed upside down, and slider is driven by inclined guide column. Mold structure design is shown in Figure 2.
Size of plastic parts is small and production batch is large, so mold design cavity ranking is 2 Cavities. Mold base is a standard mold base FCH3045 A80 B90 C78, gating system is a fine nozzle, gate is filled with glue. A disc and a cold well are designed on the end face of sprue sleeve to facilitate flow of molten plastic. An anti-rotation column is designed on the top of runner, which is convenient for manipulator to grab runner condensate. In order to resist lateral force in cavity during injection molding, four conical positioning parts 05 are designed on both sides of mold. In movable part of mold, positioning pins are designed between mold plates to increase rigidity of mold.

 

Large slider and small slider in the buckle part are combined together to form rear mold slider, small slider is an insert, and there are slopes on both sides to facilitate sliding. Slider is driven by an inclined guide column. Since slider covers the entire glue position, height of slider is relatively high. In order to increase stability of slider, 2 taper positioning blocks are designed on the top surface of each slider. Design exhaust inserts at L-shaped bone position on slider. Wear-resistant blocks are designed on the slope and bottom of slider to facilitate fly-and-adjustment.
The biggest feature of this set of mold design is that front and rear molds are all inlaid design. Full inlay design enables complex inner shape processing to be decomposed into simple grinding machine processing. At the same time, inserts can be added to place where mold needs to be vented, and matching gap of inserts can be used to exhaust. Designing inserts in places where some deep bone and hole processing, polishing and plastic filling and mold release are difficult in mold can reduce processing difficulty. Therefore, characteristics of the whole inlaid design are worthy of deep understanding and flexible application.
Number and position of split inserts is a very important task. It needs to be closely combined with company's mold manufacturing process, combined with stroke, parameters and processing range of existing machine tools, considering selection of tool parameters, and comprehensively considering injection molding, exhaust, mold polishing and other factors.
Ejection of plastic parts is ejected by ejector pins. An ejector insert 23 is designed at the bottom of ejector plate to shorten injection molding cycle. A travel switch is designed on ejector plate to ensure reliable mold reset.
Design of torso in support head is another feature of this set of molds. Pieces 6 and 7 are support head middle torsion, top is installed on the back of B plate with positioning pins, and bottom surface is fixed with mold bottom plate with screws. In actual use, this kind of middle torsion does not affect guiding performance with change of mold temperature. While guiding, it doubles as a support head, saving space and position.
Nozzle plate increases cooling circuit, designs bushing 03 around sprue sleeve to shorten injection cycle and prolong life of mold. Cooling of movable mold, fixed mold and sliding block are all direct water transportation, which has characteristics of fast flow rate and high cooling efficiency, which effectively ensures normal progress of injection molding.

 

 

 

 

Figure 2 Mold diagram of car electronic switch seat

 

 

 

Figure 3 3D view of the front and rear mold cores

 

Figure 4 Inlay of slider