关键词: 双色按键, 细水口, 浮板结构, 排气槽, 排气针, 排气镶件

Abstract: A two-color injection mold was designed according to the structural characteristics and production requirements of the two-color key plastic parts. The main body of the plastic part was made of a PC material through one-step injection. In view of the difficulty in the filling of many thin-walled bone positions set on the plastic part structure as well as the problem of excessive injection pressure， a method of fine nozzle multi-point glue injection was adaptable for this mold to address these problems. The secondary injection was conducted using TPE soft glue on the appearance surface of the plastic part. A slider core-pulling mechanism was employed for the optimized design of the three-point fine nozzle to turn the back mold vertically to flip and overlap the bottom to inject glue. This operation was cooperated with the exhaust slot， exhaust needle and exhaust insert structure to solve the problems of the inability to inject glue on the appearance surface and the TPE material being prone to trap air， which led to flow marks， air lines， and bonding lines. The special floating plate structure of the rear mold solved the problem of the isolated island glue feeding of the letter R/e/o/a on the product and the closed middle annular ring. Through actual production verification， the complete filling injection pressure was reduced by 16 % during the first injection， and there were no flow marks， air lines and poor bonding lines found during the second injection. The molding quality of products was satisfactory， and the mold design could meet the requirement of practical production.

Key words: two-color keys, fine water intake, float plate structure, exhaust tank, exhaust needle, exhaust inserts