Combination lock panel product is shown in Figure 1. Maximum size of product is 178.00 mm * 50.00mm * 24.50mm, average thickness of plastic part is 2.00 mm, material of plastic part is ABS, shrinkage rate is 1.005, and weight of plastic part is 30.90 grams. Technical requirements for plastic parts are that there must be no defects such as peaks, underfilling of injection molding, flow lines, pores, warpage deformation, silver streaks, cold materials, jet lines, etc.

 

Figure 1 Product Picture of Password Lock Panel
Structure of plastic part is a rectangular flat shell, structure of plastic part is shown in attached 3D drawing. It can be seen from 3D diagram that there are multiple undercuts on all four sides of plastic part, slider needs to be designed for molding. Front of plastic part is exterior surface, there are multiple holes on the surface, which need to be punched and formed. There are 8 side-by-side buttons on the edge, three sides of button are suspended, and only one side is connected to main structure. These 8 buttons will be difficult to fill during injection molding, and gating system needs to be designed reasonably. There are multiple dense bones on the back of plastic part, which need to be divided into inserts to facilitate exhaust.
Production volume of plastic parts is huge. Considering that four sides of plastic parts need to be designed with slider core pulls, mold design cavity is ranked as 1 cavity, mold base is a simplified fine nozzle mold base FC3040 (Fudaba standard), because plastic part has one long side and a large slider needs to be designed. Using a simplified thin nozzle mold base can save mold space and facilitate arrangement of larger width sliders.

 

Plastic flow capacity of 8 button positions of plastic part is limited. This plastic part must be aware of this when designing mold. Otherwise, the first time you try mold, you will find that plastic part cannot be filled at all, most of shell is filled, that is, 8 button positions are not filled, normal injection cannot be performed. Therefore, difficulty of this set of molds lies in design of gating system. Generally speaking, such plastic parts often require multiple gates. In modern mold design, with advanced computer software-aided design, use of mold flow analysis software can help us determine number and location of gates, so as to propose optimized design schemes for multiple mold gate design schemes.
Top surface of plastic part is exterior surface, and gate cannot be designed. Gate is designed on the side, and multiple gates are needed to fill effectively. Actual mold design is shown in Figure 2.
It can be seen from Figure 2 that design of submerged nozzle into a submerged nozzle with 3 points of glue. Gate latent mold can be broken by itself after mold is opened. Thin nozzle is turned into a submerged nozzle, break point of vertical runner is selected at the bottom of A plate frame, so that length of vertical runner can be reduced, opening distance of mold plate can be reduced, which is convenient for injection molding.
All sliders are driven by oblique guide posts. Large sliding block and sliding block with two end faces have a large area and large lateral force, so backhoe structure is designed, that is, sliding block is locked on inclined surface of movable mold. There is no backhoe mechanism for small sliders with two side buckles.
There are many kinds of mold opening drive structures for three-plate molds. This set of molds adopts pull plate drive, which has low cost of pull plate drive, simple processing, and does not occupy internal space of mold. When designing pull plate drive, you need to pay attention to that four pull plates need to be designed in a symmetrical position on mold, and do not interfere with water transport joint.
Ejection of plastic parts adopts thimble, flat thimble and tube ejection.
Both front and back molds of mold are designed with cooling circuits to ensure normal injection molding.

 

 

 

 

 

 

Figure 2 Diagram of mold of combination lock panel