Printer clamshell product is shown in Figure 1. Maximum external dimensions of product are 197.86 mm * 130.14 mm * 45.20 mm, average plastic position thickness of plastic parts is 2.0 mm, material of plastic parts is HI-PS, shrinkage rate is 1.005, weight of plastic parts is 60.62 grams. Technical requirements of plastic parts are that there must be no defects such as peaks, unfilling of injection molding, flow lines, pores, warpage, silver lines, cold materials, spray lines and other defects. Difficulty of mold design is that front and rear molds need to be designed with oblique core-pulling mechanism, and plastic parts must not be deformed after molding. Front and back molds of plastic parts are appearance surfaces, gate marks and eject marks cannot be produced.

 

 

Figure 1 Printer flip product picture

It can be seen from Figure 1 that shape of plastic parts is relatively simple, and overall shape is a circular flat plate. Clamping line at the front and back mold package R of plastic part edge should be uniform, and step difference should not exceed 0.03mm. Parting surface is a curved surface. Processing of parting surface should be processed by high-speed machine at one time, and it cannot be trimmed by hand file.

 

 

Design rank of mold is 1 out 2. Slider core of two plastic parts has a small core pulling distance and is arranged in the middle of mold. Oblique slider at oblique surface of front mold of plastic part has a long core pulling distance and is arranged on both sides of mold. Shape of plastic parts is smooth, which is conducive to flow of plastics. Gate is designed at the middle of plastic part, and type is side gate. Mold base is LKM standard mold base LKM GCH5060 A120 B100 C120-350, simplifying fine nozzle. Front and rear mold core materials are NAK80. NAK80 belongs to pre-hardened steel with the largest material hardness, hardness HRC38~41, and has good polishing performance. Due to large size of plastic parts, size of front and rear mold cores is correspondingly large, so mold cores of two cavities are designed separately. Size of mold core is 205*290, and it is more difficult to match frame of mold core. Therefore, front and rear mold cores are all pressed and positioned after being pressed by squeezing block. Fine frames of front and rear molds and squeeze block grooves are processed together in mold base factory to prevent deformation. Conical positioning parts are used for precise positioning of front and rear molds, one for each side.
In order to simplify mold design, two pillars at the corners of edges of plastic parts are driven by core slide of rear mold and inclined guide columns. Difficulty of using oblique core pulling is avoided.
After mold is opened, first, panel is separated from plate A, shovel of front mold inclined slider leaves slider, under action of the spring, core of front mold inclined slider is completed. Then nylon buckle of parting surface is opened, four small sliders in the middle realize buckling and demoulding. Then, B plate is separated from backing plate under action of spring, and T-slot slider of rear mold completes core position of column.
No ejector pin should be designed on back mold of plastic parts, so as not to affect appearance. Ejection adopts ejection block designed on the edge of plastic part.
Cooling of mold adopts design of front mold to pass through water. Back mold water tank is fully cooled to ensure injection cycle and avoid deformation of plastic parts.

 

 

Figure 2 Flip mold of printer

 

Figure 3 mold photo