Inner surface of automobile glass window decorative plate has 4 buckle positions, and its opening direction is arrow shown in Figure 1. Structure of plastic part is shown in Figure 2. Outer dimensions are 411mm×203mm×37mm, wall thickness is 4mm, and outer surface is slightly arched. In order to increase sealing of glass window and prevent water leakage, a reinforcing rib is set inside buckle position ①, and height of reinforcing rib is 1mm; in order to prevent outer surface corresponding to root of buckle position ① from shrinking, a material reduction groove is set at the root of buckle position ①, and wall thickness of buckle position root is only 1mm, angle between side and bottom of material reduction groove is 50°. Distance between reinforcing rib and material reduction groove is relatively close. Due to obstruction of reinforcing rib, slider cannot be demolded in V1 direction, and due to obstruction of side wall of material reduction groove, it cannot be demolded in V2 direction. It can only be demolded in direction of opening of material reduction groove (V3 direction). Since size of buckle position ① is small, cross-sectional size is only 28mm×18mm, and it is impossible to design two independently running slider demolding. For this structure, a slider linkage demolding mechanism is designed in which large slider drives small slider to move.

 

Linkage slider mechanism is mainly composed of a large slider, a small slider, a wedge, a slider seat, a spring, a blocking block, a blocking bar, a T-shaped guide rail, a limit column, a guide block, etc. Structure is shown in Figure 3.

 

1. Locking block 2. Wedge 3. Slider seat 4. Stop block 5. Spring 6. Stop bar 7. Fixed mold plate 8. Fixed mold insert 9. Small slider 10. Limiting column 11. Large slider 12. Moving mold insert 13. Moving mold plate 14. T-shaped guide rail 15. Guide block
Figure 3 Linkage slider mechanism
Upper surface of large slider is an inclined surface. When mold is opened, small slider 9 slides on upper surface of large slider 11. Two mechanisms are set inside linkage slider mechanism: ① A spring 5 is set between slider seat 3 and small slider 9, and small slider 9 is pushed away from slider seat 3 by elastic force of spring 5; ② A blocking block 4 is set on fixed mold plate 7, and a blocking bar 6 is set on small slider 9. Blocking bar 6 and small slider 9 are fixed with screws. Contact surface between blocking block 4 and blocking bar 6 is a vertical surface. In initial stage of mold opening, inclined wedge 2 drives large slider 11 to move laterally, and blocking block 4 moves upward with fixed mold plate 7. Blocking block 4 will prevent small slider 9 from moving laterally and push small slider 9 away from slider seat 3. Above two mechanisms can make small slider 9 slide on upper surface of large slider 11. Upper surface of large slider 11 is an inclined surface. An inclined T-shaped guide rail 14 is set on upper surface of large slider 11. When small slider slides along upper surface of large slider, T-shaped guide rail will cause small slider to move in vertical direction.
In order to make small slider move along opening direction of material reduction groove, a guide block is set at each end of small slider. Guide block structure is shown in Figure 4, and buckle position of end face of small slider is shown in Figure 4 (c).

 

A 50° inclined surface is set on guide block, and inclined surface is consistent with inclination of material reduction groove. A buckle position is set at each end of small slider, and buckle position matches guide block. When opening mold, small slider slides along T-shaped guide rail on upper surface of large slider toward opening direction of material reduction groove under action of inclined surface of guide block, so that buckle position and material reduction groove are demolded. When closing mold, buckle position of guide block can fix position of small slider in mold to prevent small slider from moving toward center of mold. Movement process of linkage slider: Since height of vertical surface of blocking block 4 is 45mm, when mold opening distance is 0~45mm, inclined wedge 2 leads slider seat 3 and large slider 11 to move in horizontal direction, blocking block 4 and spring 5 push small slider 9 away from slider seat, so that small slider 9 slides on upper surface of large slider 11. Upper surface of large slider 11 is an inclined surface. A T-shaped guide rail 14 is provided on upper surface of large slider 11. Under its action, small slider 9 will move vertically downward. Under guidance of guide block 15, small slider 9 moves along 50° inclined surface of guide block to demold reinforcing ribs and material reduction groove. When mold separation distance is 45mm, blocking block 4 is out of contact with blocking bar 6. At this time, reinforcing ribs and material reduction groove have been completely demolded. Driven by limit column 10 on upper surface of large slider, small slider 9 follows large slider 11 to perform demolding movement in horizontal direction until buckle position ① is completely demolded. When mold is closed, movement process of linkage slider is just opposite.

Buckle position ② opens toward inside of plastic part, and an oblique push mechanism is used for demolding. Since size of buckle position ② is 10mm×7mm×331mm, cross-section is small, but its length is long. In order to strengthen rigidity of push block and prevent deformation, cross-section of push block needs to be enlarged, and cross-section of push block is designed to be 46mm×63mm, as shown in Figure 5 (a). Push mechanism adopts a combined structure, which consists of a push block, a push sleeve, a push rod, a reinforcing rod, and a push seat, as shown in Figures 5 (b) and (c). Push block is large in size and supported by two push rods, so that push block can maintain balance during movement. Inside of push rod is a hollow tube that can be connected to waterway. In order to prevent push rod from being deformed due to excessive force, a reinforcing rod is set next to push rod, and reinforcing rod bears twisting force during pushing. In order to set a cooling water circuit inside push mechanism, push rod is connected to inlet and outlet water pipes, and a push sleeve is installed on push rod to prevent wear.

 

1. Oblique push block 2. Oblique push sleeve 3. Oblique push rod 4. Oblique push seat 5. Inlet and outlet pipes 6. Reinforcement rod
Figure 5 Combined oblique push mechanism

Use oblique push mechanism to demold buckle position ③. Since demolding angle of buckle position is large (70°), it is easy to get stuck if oblique push seat directly pushes oblique push rod. A rack oblique push mechanism driven by a straight rack is used, as shown in Figure 6 (a). An oblique rack is designed on oblique push rod and straight rack is fixed on push plate. Oblique push seat has two guide grooves, as shown in Figure 6 (b), one of which is a vertical groove to guide movement of vertical rack; the other is an oblique groove to guide movement of oblique push rod. When opening mold, push plate pushes straight rack upward, then straight rack pushes oblique rack upward to demold buckle position ③.

 

Contour of plastic part is relatively neat, and corresponding parting surface is relatively smooth. Parting surface of mold is a straight curved surface created by parting lines of two plastic parts. There are no sharp corners or corners on parting surface. Left and right glass window decorative panels of car are molded simultaneously using 2 cavities. Without affecting strength of mold parts, moving and fixed mold cores adopt an insert structure. Insert size is 570mm×490mm×84mm, which is relatively large and relatively thin. In order to increase strength and rigidity of insert, prevent deformation of moving and fixed mold inserts, moving and fixed mold inserts are divided into 2 pieces. Matching width of parting surface is designed to be 30mm, and remaining parts are designed with a mold clearance of 0.3mm. Volume of plastic part is large, and several exhaust grooves are opened on parting surface to allow air in cavity to be discharged smoothly. Positioning bosses and positioning grooves with a side slope of 5° are set on moving and fixed mold inserts to increase mold closing accuracy of moving and fixed molds, prevent dislocation, as shown in Figure 7.

 

Automotive glass window decorative panel is an appearance part, and outer surface is required to be free of defects such as gate marks, shrinkage, burning, and weld lines. In order to overcome defects of direct casting of ordinary runners, hot runners are used to convert ordinary runners and then side gates are used for feeding. According to manufacturing experience of similar molds, two gates are set at both ends of plastic part to be molded, as shown in Figure 8. After plastic part is assembled on car, two ends are covered by other parts, and gate marks will not affect appearance. In order to facilitate trimming of gate condensate, a fan-shaped gate is selected for feeding.

 

Different cooling water channels are used according to structure of movable and fixed molds. Fixed mold is suitable for straight-through cooling water channels. Since temperature of hot runner is high, in order to reduce temperature of this area, cooling water channels are arranged more densely near hot runner. Fixed mold is divided into 6 groups of independent water channels, represented by A~F, as shown in Figure 9 (a).
There are 2 combined oblique push mechanisms, 2 rack oblique push mechanisms and several push rods on movable mold, which are suitable for water well cooling water channels, and water wells are connected by straight-through water channels, which are divided into 4 groups of independent water channels, represented by a~d, as shown in Figure 9 (b). In order to make mold temperature of each part uniform, distance between water channel and cavity is about 15~20mm, and interval between water channels is uniform, about 25~30mm. Due to large size of linkage slider and combined oblique push mechanism, a separate cooling water channel needs to be set.

 

Mold is designed as a 2-cavity layout, with 2 plastic parts placed opposite to each other, 2 large slider mechanisms installed on both sides of mold, and 2 oblique push mechanisms arranged oppositely. Oblique push mechanism and slider mechanism both adopt a combined structure. When mold is opened, forces of 2 slider mechanisms and 2 oblique push mechanisms are balanced with each other. Mold structure is shown in Figure 10.
Among them, locking block 7, slider seat 8, blocking block 9, blocking bar 10, small slider 18, large slider 19, and oblique wedge 20 form a linkage slider mechanism, slider 30 and oblique guide column 31 form oblique guide column + slider demoulding mechanism of buckle position ④, and large oblique push rod 23, small oblique push rod 25, pull rod 32 and all push rods 22 are the ejection mechanism of mold. When injection is completed, movable mold and fixed mold are separated at contact surface of movable mold plate 6 and fixed mold plate 11. When movable mold is separated from fixed mold, following two mold opening actions are performed simultaneously: one is that inclined guide column 31 guides slider 30 to perform lateral demolding movement; the other is that inclined wedge 20 guides linkage slider mechanism to perform demolding movement. When injection molding machine ejector leads movable mold part to move to extreme position, injection molding machine ejector pushes ejection mechanism to perform demolding movement. After plastic part is ejected, injection molding machine ejector drives ejection mechanism of mold to reset together. After reset is completed, injection molding machine ejector pushes mold to start closing mold, and following three actions are performed simultaneously: ① Wedge block 29 and inclined guide column 31 guide slider 30 to reset; ② Inclined wedge 20 guides linkage slider mechanism to reset; ③ Reset rod 24 guides ejection mechanism to reset. When mold is completely reset, next production cycle begins.

 

1. Moving mold base plate 2. Pad 3. Push plate limit column 4, Push plate 5, Push rod fixing plate 6. Moving mold plate 7. Locking block 8. Slider seat 9. Blocking block 10. Blocking bar 11. Fixed mold plate 12. Hot runner plate 13. Fixed mold base plate 14. Heat insulation board 15. Hot runner electrical components 16. Positioning ring 17. Fixed mold insert 18. Small slider 19. Large slider 20. Wedge 21. Moving mold insert 22. Push rod 23. Large inclined push rod 24. Reset rod 25. Small inclined push rod 26. Moving mold insert inclined wedge 27. Fixed mold insert inclined wedge 28. Hot runner nozzle 29. Wedge block 30. Slider 31. Inclined guide column 32. Pull rod 33. Push plate limit column 34. Push plate guide column
Figure 10 Mold structure