Unscrewed By A Spring-Operated Sleeve

The workplece shown in Fig. 6.64 is provided with a fine intermal thread.

The plastic material flows into the nest through the side gate. The workpiece thread is machined by spring-operated sleeve 8(Fig. 6.64b). The material of the spring-operated sleeve 8 strain pin 12 and split eiector sleeve 18 is spring steel. The strain pin 12 is fixed on the mobile clamping plate 11

Operation: The residual material is pulled out of the sprue bush 23 with the mold opening (Fig.6. 64c). During the ejection process, shaped plate 3 goes with spring-operated sleeve 8 together, because the shaped plate 3 is acted by split sleev 18 which is connected with ejection system 14 and 15. when the opening of the mold clears the height of the workpiece by a few millimeter,the cam of the spring-operated sleeve 8 engages the tapered bush 7, and it is compressed according to the depth of the thread (Fig. 6.64d). Upon further ejecting, the shaped plate 3 stops with the aid of split sleev 18 contraction, so that the workpiece is pushed out of nest of the shaped plate 3 by spring-operated sleev 8, and the workpiece together with the residual material in the runner fall out of the mold(Fig. 6.64e). Upon closing of the mold, the ejector plates 14 and 15 are returned to their initial position by return pins 10. Upon closing of the injection mold, the returning pin 10 pushs the ejector system back, the strain pin 12 forces the spring-operated sleeve 8, and fixes it (Fig.6.64a).

Advantage: the injection process can be in automatic operation. The production is in higher efficiency than those mold with unscrewing mechanism by rack and gears.

Disadvantage: the thread is discontinuous.