Demoulding of helical gear moulded parts

For plastic helical gears, the tooth surface is a helical involute curved surface, and the direction of the curved surface has a helix angle to the direction of mold opening and taking out of the injection mold. During the mold-opening process of injection molding, the molded part is pushed out in a straight line along the mold-opening direction under the action of the ejection mechanism. At the same time, the molded part or the tooth-shaped cavity rotates in the direction of the tooth-shaped tilt, thereby achieving the oblique Smooth demoulding of gear plastic parts.

Aiming at the design of the demolding mechanism of the helical gear injection mold, Qu Huachang introduced two types of demolding mechanisms, namely the tooth-shaped cavity rotary type and the gear molded rotary type; Wu Xianming and others introduced the mold structure of the double plastic gear (one helical tooth and one tooth) And the working process of mold opening and taking parts and the mold cavity manufacturing process adopted to ensure gear accuracy: Tao Yongliang, Zhao Shiyou, Qu Fanmin, Zhou Huilan, etc. The relevant research results and practical experience based on the injection molding of specific plastic helical gears are summarized as plastic skew The design and manufacture of gear injection molds provide a reference basis. However, none of the above documents involves the forming and demolding of double helical gears. The co-rotating double helical gear forming and demolding mechanism proposed by Jiang Changyong has certain engineering application value, which helps guide the practice of mold design. Chinese Patent CN2013100753976 (Patent Name "A screw demolding device for helical gear injection mold"). The structure uses a device consisting of a rotating cavity, a movable mold carrier plate, a pressure plate and a bearing, because it will be used in the implementation process. As a result, the heat exchange efficiency of mold temperature adjustment is reduced, the molding cycle becomes longer, and the rotational friction of the cavity increases, so it is difficult to ensure the molding accuracy of the gear. The mold mentioned in the Chinese patent CN2011103817773 patent title "Reset structure of helical gear mold and helical gear mold"), the strength of the gear cavity will become worse during the specific implementation process, and the long-term friction between the reset rod and the positioning hole will be Affect the reset accuracy of the gear cavity of the mold. The structure of the mold mentioned in the Chinese patent CN201310733404.7 (patent name "plastic helical gear injection molding demoulding structure") cannot solve the problem of deformation in the demolding process of plastic parts. The mold mentioned in the Chinese patent ZL2012101597843 (patent name "Double helical gear injection molding demoulding mechanism") uses a combination of centripetal thrust ball bearings and plane thrust ball bearings to make the tooth shape cavity of the double helical gear Rotation, the mold design only solves the problem of forming and demolding double helical gears in the same direction, but there is no literature or patent report for the forming and demolding of double helical gears in different directions.