Plastic worm automatic mold ejection technology is a high-end technology in gear mold. It needs to rotate the mold synchronously to ensure the accuracy of the injection product and the injection cycle can not be too long (involving the production cost). The existing technology is generally driven by oil pressure, and the transmission part adopts synchronous thread, which is the same as the product lead, When the product rotates out of the mold, the overall speed is not balanced, and the force is not the same. The lead of the product after injection molding changes greatly, which usually can not meet the accuracy requirements of the product drawing. Moreover, the use of synchronous thread makes the mold manufacturing complex, and the lead of the product tooth germ itself also has different degrees of error, and the cost is very high.
The main machining surface of worm is cylindrical surface, and there are also common special surface. Therefore, according to various accuracy levels and surface roughness requirements, the machining method is selected according to economic accuracy. For ordinary precision worm shaft machining, the typical process route is as follows:
Blank and its heat treatment - pre processing - turning cylindrical - milling KEYWAY - (spline groove, groove) - heat treatment - grinding - tooth profile detection.
1. Pre machining of worm shaft
The pre machining of shaft parts refers to the preparation process of machining, that is, the process before turning the outer circle.
Straightening: in the process of manufacturing, transportation and storage, bending deformation often occurs. In order to ensure uniform machining allowance and reliable clamping, straightening is usually carried out on various presses or check-in machines under cold state.
2. Positioning datum and clamping of worm shaft machining
(1) The central hole of the workpiece is used to locate the axis in the machining process. The coaxiality of the outer circle surface, the taper hole and the thread surface, and the perpendicularity of the end face to the rotation axis are the main items of their mutual position accuracy. The design basis of these surfaces is generally the central line of the axis. If two central holes are used to locate, it is in line with the principle of datum coincidence. The center hole is not only the datum for turning, but also the positioning datum and inspection datum for machining process, and it conforms to the principle of datum unification. When two center holes are used for positioning, a plurality of outer circles and end faces can be machined to the greatest extent in one clamping.
(2) The outer circle and the center hole are used as the positioning datum (one clip and one top). Although the positioning accuracy of two center holes is high, the rigidity is poor, especially when machining heavy workpieces, it is not stable enough, and the cutting parameters should not be too large. In rough machining, in order to improve the stiffness of the parts, the cylindrical surface of the shaft and a central hole can be used as the positioning datum. This positioning method can bear large cutting torque and is the most common positioning method for shaft parts.
(3) When machining the inner hole of hollow shaft (for example, machining the inner hole of Morse taper on the machine tool), the center hole can not be used as the positioning datum, but the two outer circular surfaces of the shaft can be used as the positioning datum. When the workpiece is the spindle of the machine tool, the two supporting journals (assembly datum) are often used as the positioning datum, which can ensure the coaxiality requirement of the taper hole relative to the supporting journal and eliminate the error caused by the non coincidence of datum.
(4) When machining the cylindrical surface of hollow shaft, the cone plug or sleeve mandrel instead of the central hole is often used as the positioning datum.
Zhongshan Sani Transmission Technology Co., Ltd. is specialized in the R & D, production and assembly of various plastic gears, worms, transmission parts, precision plastic parts and gears. Our company has a gear testing center to test the quality of products to meet the requirements of users
Contact: Jack He
Add: BuildingA 125 WeiMin Road,DongSheng Town,ZhongShan city,GuangDong Province,China