The computer keyboard is the main input device in the computer. The keyboards are mainly divided into three parts: upper shell、lower shell and keys .The most important is key technology will affects the quality of the keyboard that we distinguish from surface and edge are reasonable. A bad keyboard has a rough surface, the keys don’t bounce when we press them down, and the key character is screen printing is easy to wear, on the contrary good quality keyboard keys on the character is laser engraving that is not easy to fall off and wear .
The computer keyboard key material is ABS, the shrinkage rate is 1.005, the plastic part size is small, and the shape is simple, there are two inverted buckle used for assembly, The inverted buckle can not be used slider core pulling or inclined ejecting mold ,because the space position is small,. The problem of the reverse out of the mold is the difficulty of the mold design.
The mold design drawing is shown in Figure 1. The problem of demoulding of plastic parts is solved by using the method of secondary ejection. Due to the small space position, a flexible straight roof is designed for the two inverted positions respectively. The two elastic straight roofs are assembled on the bottom thimble plate, and the round thimble at the four corners of the plastic parts is designed on the upper thimble plate.
After the die is opened, the top rod of the injection molding machine pushes the lower thimble plate, and the elastic straight top and round thimble push the key out from the rear die kernel together to make room for the deformation of the reverse position. If ejecting continues, the lower thimble plate is limited by square iron, the upper thimble plate is warped by lever to accelerate ejecting, the round thimble separates the plastic ejecting from the elastic straight roof, and the inverted position realizes strong ejecting.
The button strength and operating comfort is a key parameter of the button. The height of the key center column is a very important factor affecting the key strength. For this reason, the insert pin in the center of the key should not exceed the height tolerance of ±0.02. The mold design adopts a 21-cavity multi-cavity arrangement, and the glue is fed through the water inlet and the glue is fed through the side gate from the edge of the plastic parts. The flow channel forms a closed frame for subsequent oil injection and laser engraving. After the completion of all procedures, then use the manual punch down the runner and gate.