Total station movement support product is shown in Figure 1. Maximum size of product is 121.13 mm * 53.10 mm * 32.15 mm, average thickness of plastic part is 1.50 mm, material of plastic part is ABS, shrinkage rate is 1.005, and weight of plastic part is 13.28 Grams. Technical requirements of 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 diagram of total station movement bracket
Plastic part structure is shaped as a special-shaped bracket shell. Plastic part structure and 3D mold design drawing are shown in attached 3D drawing. Plastic part is close to a closed U-shape, with a protrusion on closed end and a small hole on it. Here, slider core needs to be designed. There is a vertical wall on two sides of plastic part with several small holes, and it is also necessary to design slider core.
Inside of plastic part is smooth and flat. Except for closed end, the rest has no bone positions. Clamping force for mold is limited to 3 side edges. There are many bone and column positions on the top surface of outer side of plastic part, which have a large tightening force for mold. Therefore, when designing mold, it is necessary to determine direction of mold opening according to packing force of plastic part. After mold opening direction is determined, correct parting surface can be designed.

 

In view of actual situation of plastic part, when designing mold, inside of plastic part must be used as fixed mold, top surface of outside must be used as movable mold, so as to ensure that plastic part does not stick to fixed mold when mold is opened. Mold design drawing is shown in Figure 2.
Structure of plastic part is more complicated. Mold design cavity ranks 1 cavity. Holes on vertical side of side and holes on the end face are combined to design a large slider, and the other side is designed with a slider. Two sliders are used to solve core pulling problem. Both sliders are driven by oblique guide posts. Due to limited space position, small slider adopts single-sided bead guide. Large sliding block on the end face has a great expansion force, and inclined wedge is designed to go deep into movable mold backhoe. Mold base is standard mold base FCI2330, and gating system uses a fine nozzle to turn a side gate to feed glue from one side of plastic part.
Mold cooling system is designed with two straight-line, straight-through water-carrying designs for both movable and fixed molds. Flow of through water is large and cooling efficiency is the highest. Design through water as much as possible.
All plastic parts are ejected by a thimble. All thimble holes are cut by wire cutting. Exhaust holes need to be ground on the circumference of thimble. When matching thimble, it should be noted that after thimble is installed, it needs to be twisted to be able to rotate flexibly. Only in this way can it have a long life in subsequent production. In higher temperature molds, SKD61 heat-resistant thimble is used, and surface of titanium plating can delay its surface wear. It is also possible to use SKH51 high-speed steel thimble when conditions are available, with a longer life.

 

 

 

 

 

Figure 2 Mould diagram of core support of the total station