Due to large molding area of slider and lifter area of this mold, cooling water is designed for both slider and lifter to ensure uniform and sufficient cooling of plastic parts, avoid local overheating of plastic parts. For parts weighing more than 8KG, process lifting holes are designed to facilitate fitter assembly operations. Sliders are designed with process screw holes and conical surface positioning to facilitate slider and fixed mold to be clamped together to save molds, thereby ensuring that plastic part clamp line is uniform and delicate, meeting quality requirements of automotive exterior parts.

 

When designing an inclined slider that pulls core along Z axis up and down, it is necessary to pay attention to following: 1. Inclination of inclined slider A should be greater than angle of inclined slider B by more than 2 degrees to avoid undercuts and damage to plastic parts. 2. Design of cooling water and spring of inclined slider must be parallel to core pulling angle of inclined slider to facilitate processing of inclined slider. 3. When ordering inclined slider, it is necessary to order blank along inclined direction of inclined slider to facilitate subsequent processing. 4. Inclined slider is driven by inclined guide column. The larger inclined slider is, the greater torque is. In actual production of mold, inclined guide column often breaks, so inclined guide column should be designed to be as strong as possible. 5. Inclined guide column with a diameter of less than 20 is replaced by SKD61 ejector pin, and diameter of more than 25 is replaced by SUJ2, which requires high-frequency quenching. 6. When designing core pulling structure of slider, try to use original body to leave shovel base, use local materials, and reduce mold cost.

 

 

This mold slider S1 is a fixed mold tunnel inclined slider structure, which is at an angle of 11 degrees with vertical direction of the Z axis. Relying on opening and closing of fixed mold panel and A plate and inclined guide column drive, it is a typical "three plates + inclined guide column" drive structure. Core pulling stroke is 60mm, core pulling distance is large, and core pulling forms an angle of 11 degrees with Z axis. Therefore, rationality of design of inclined guide column is very important. Inclined guide column of this mold uses D30 specification, and angle of inclined guide column is 23 degrees. Generally, inclined guide column is most stable and reliable at 12-18 degrees. When it exceeds 18 degrees, torque force is large. Inclined guide column needs to be designed to be stronger to prevent inclined guide column from breaking during production. Since core pulling projection area of S1 is large, injection pressure is large. In order to prevent slider from retreating during injection, a wear-resistant block is designed on shovel base, which is at an angle of 5 degrees with slider protection plate, a backhoe structure is designed to prevent slider from retreating and plastic part from flashing.

 

S1 slider is a tunnel core pulling inclined slider structure. Front end of slider insert needs to be designed with a 1-3 degree slope, rear slider seat needs to be designed with a step positioning to facilitate fitter FIT mold and processing data. Wear blocks are designed on four sides of slider seat, and wear blocks protrude 1mm from surface of slider seat, which is convenient for fitters to match mold and avoid fitters grinding slider seat to avoid affecting appearance of mold workpiece. Slider insert is sunk 15mm into slider seat for positioning on all four sides. S1 slider of this mold is driven by three plates and inclined guide columns, shovel base is sunk 25mm into panel for positioning and fastened with 4 M12 screws. Slider is positioned and stroke is controlled by slider positioning clamp and limit column. Wear blocks are designed on the bottom and back of slider. Length and width of wear blocks are at least controlled in sliding area of 2/3 of slider. Thickness is generally selected from 6-12mm, and this mold uses 12mm.

 

Wear blocks on the back and bottom of slider need to be positioned in at least two directions. It is best to design four directions for positioning, and wear blocks are tightly matched with wear block grooves. Wear blocks are sunk into groove, and surface protrudes 1mm. Slider seat is pressed by pressure block guide, pressure block guide length is at least 2/3 of slider length to ensure smooth and reliable core pulling of slider. S1 is designed with a slider fixing seat, which controls slider stroke and installs slider pressure blocks and wear-resistant blocks. A slider protection block is designed on the outside to facilitate design of shovel base backhoe mechanism and protect slider. Slider fixing block is fixed on A plate and fastened by 4 M10 screws. At the same time, front end of slider fixing block is partially sunk into A plate 15mm for positioning, which effectively ensures precise positioning of fixing seat. Since ribs in S1 slider are crisscrossed and there are 4 pillars, mold flow analysis shows that this is air-trapping area. Therefore, many special-shaped inserts are designed, which are fastened by screws and sunk into slider for positioning. 4 pillars are all pin-studded.

 

(For 4 pillars of mirror seat plastic, use of a sleeve will be more stable and plastic will not be easily deformed. However, design of sleeve will make slider structure more complicated. In order to simplify mold structure, 4 pillars here are all pin-studded) Gap between insert, pin and slider is used to exhaust air, which effectively solves problem of air trapped in ribs. To prevent slider from sticking, demoulding slope of all ribs and columns along slider core pulling direction is designed to be as large as possible, generally designed to be more than 1 degree. Slider needs to be designed with cooling water, and S1 slider uses 3 water wells for cooling.

Lateral core pulling mechanism is the most important and most complex structure in this mold. Not only is there a large number of them, but core pulling directions are also inconsistent. All are oblique core pulling, and none is perpendicular to mold opening direction.

 

Core pulling has both outer core pulling and inner core pulling, and there are two core pullings toward center of mold. It is one of the most complex molds in lateral core pulling mechanism of automotive injection molds. When designing lateral core pulling mechanism, we adopted following advanced structures and achieved satisfactory molding results.

 

Figure 2 Lateral core pulling mechanism of injection mold for automobile headlight lens
29, 36, 38-wear-resistant blocks; 30-spring; 31-limiting screw; 32-limiting pin; 33-support column; 34-T-slot guide block; 35-wedge-tightening block; 37-oblique inner core pulling
(1) Front end of outer oblique sliders 12 and 27 is designed with a 3° insertion angle on one side, which not only improves service life of mold, but also increases stability and safety of mold.
(2) Wear-resistant blocks are designed on all four sides of oblique inner core pull 37, which not only increases service life of inner slider, but also facilitates mold matching and maintenance. Wedge block 35 is designed with a 5° anti-locking structure to prevent slider from retreating under action of injection pressure.
(3) Since a part of oblique inner core pull 37 remains on T-slot of T-slot guide block 34 after core pull, T-slot cannot be left empty. Therefore, a rounded corner is designed on inner side of T-slot to avoid stress cracking.
(4) In view of insufficient strength and rigidity of movable support plate at oblique core pull on inner side of movable mold, a support column 33 is designed at the center and near inner core pull to strengthen mold strength and prevent mold from deformation.
(5) In order to solve problem that outer slider of mold leaves an obvious inlay line on plastic part, affecting appearance, all slider heads are designed to be conical, and process screw holes are designed on all sliders. When cavity is polished, it is fixed together with fixed mold A plate 2 by screws to ensure that inlay is flat and beautiful.