Battery rotating shaft
Injection molds generally have domestic molds and foreign molds. Generally, domestic molds have lower requirements and lower prices, while foreign molds have high requirements and high prices, so requirements for mold design and manufacturing are very high. Compared with domestic molds, export molds mainly require more and higher requirements, are more complicated, and have high requirements for detail design. Whether it is appearance, strength, standard parts, hot runners, steel, etc. of mold, they are much stricter than domestic molds. Export molds we are in contact with are generally exported to Japan, Europe, America and other countries. Each country has its own design and manufacturing standards. For example, Japan generally adopts Misumi standard, Europe and United States generally adopt HASCO and DME standards. These are three major standards for commonly used export molds. This article takes a set of injection molds exported to United States as an example to discuss key points of European and American injection mold design.

 

Following figure shows a part drawing of a battery rotating shaft of a certain brand. Material is ABS and it belongs to appearance part. Size of plastic part is: D48x54.6mm. Characteristics of plastic part are as follows: (1) There are no spots, shrinkage depressions, weld marks, flash and other defects on appearance of plastic part. (2) There are two undercuts on outer side of plastic part, and a slider structure is required. (3) Surface treatment of fixed and movable molds is SPI-C2. SPI-C2 is an American standard for surface finish. SPI-C2 is equivalent to 400# oilstone.

 

According to structural characteristics and appearance requirements of battery rotating shaft plastic part, mold adopts a large water inlet to a diving inlet for glue feeding, and mold cavity arrangement is: 1X4. There are two undercuts S1 and S2 on outer side of plastic part, and a slider structure is required. There is no undercut on inner side of plastic part. As shown in figure below. Maximum outer dimensions of this mold are: 350*600*401 (mm).

 

Mold structure
According to structural characteristics and appearance requirements of battery rotating shaft plastic parts, mold adopts a large water inlet to a submersible inlet for glue injection, and mold cavity is arranged as: 1X4. There are two undercuts S1 and S2 on outer side of plastic part, and a slider structure is required. There is no undercut on inner side of plastic part. As shown in Figure 3. Maximum outer dimensions of this mold are: 350*600*401 (mm). See figure below for detailed structure.

 

How to arrange this product at the beginning of design is a problem. Considering mold structure, products are arranged in a long line to facilitate glue injection and slider structure.

 

Product glue injection
Product adopts a large water inlet to a submersible inlet for glue injection, flow channel is on the front mold and slide position. Glue injection point is directly opened on the surface of product where it does not affect appearance. Since plastic part is arranged as 1*4, fixed mold core is only designed with a single-sided flow channel, and flow channel is a trapezoidal flow channel.

 

Mold structure
There are two undercuts on outer side of plastic part, and a slider structure is used. As shown in Figure 7. Slider of this mold is a split slider. Two sliders need to be positioned with a tiger's mouth. Two sides of slider insert need to be inclined at 3-7 degrees, and bottom of slider insert needs to be inclined at 3 degrees to increase service life of mold.

 

This mold is a push block ejection structure, and push rod needs to be positioned to prevent rotation. After mold is opened in fixed and movable molds, push block is used to push out plastic part. Push piece fixing plate is pushed by injection molding machine through oil cylinder and reset under action of 4 reset rods. After mold is opened in fixed and movable molds, mold ejection system is used to push out plastic part. Push piece fixing plate is mechanically pushed by injection molding machine through KO hole and reset under action of 4 reset rods.

 

Overall rear mold

 

Overall front mold

 

Overall 3D