PRODUCT OVERVIEW EARLY RETURN UNITS FOR EJECTOR PLATES
■ Fig.2: Movements of the early return units for ejector plate
■ What is the Early Return Units for Ejector Plate? • In the case that there is an ejector pin within the movement range of the slide core, there might be a collision of the ejector pin and the slide core before the slide core returns to its initial position in the mold closing process even if you use a return pin, which could result in serious damage. (Refer to Fig.1- ④ ) Usually, the ejector plate is supposed to return by the return pin and spring. However, a malfunction could also occur in the following cases. 1) Scoring on the ejector pin and return pin 2) Breakage and fatigue on the spring 3) The long stroke of the ejector pin hinders the plate from returning to its initial position by the spring The Early Return Units for Ejector Plate are intended to push down the ejector plate earlier than the return pin in order to prevent the slide core and ejector pin from colliding. ■ Features • This is embedded into the unit, which is space-saving and easy to mount. Early return can be ensured even when eject stroke of the ejector pin is rather long. • The length of the bushing, cam rod and push pins can be specified in 1 mm, 0.5 mm and 0.01 mm respectively, which allows an easy mount- ing to the mold. • This can be used for the two-step ejector. ■ Fig.1: Example of activation of early return units for ejector plate
[Early return unit] ① Mold opened
(During ejection of the ejector plate) The cam in the cam rod is moving along the inside wall of the bushing. ② Mold closing ( Ⅰ ) The cam is pushed by the push pin as the movable mold plate moves, which triggers the return of the ejector plate. ③ Mold closing ( Ⅱ ) Almost at the same time that the ejector plate returns to its initial position, which accompanied the cam pushed by the push pin, the cam evacuates to the space at the end of the bushing. ④ Mold closed The push pin is inserted into the cam rod without interference of the cam, which cleared the way for the push pin. That completes the mold closing with- out breakage.
Fixed mold plate
Push pin
Bushing
Cam
Cam rod
Movable mold plate
Back up plate
Ejector plate (upper) Ejector plate (lower)
④ Mold closed
Collision between slide core and ejector pin
Spacer
Early Return Units for Ejector Plate
③ Mold closing ( Ⅱ )
② Mold closing ( Ⅰ )
Base clamping plate
Return pin
① Mold opened
■ Fig.3: Activation condition of two-step ejection unit
[Two-step ejection unit] Use the unit when it is difficult to eject the finished products with one-step ejection or when you want to have the finished products automatically fall. ① Mold opening → First-step ejection When the ejector plate ( Ⅰ ) is ejected, both the bushing and ejector plate ( Ⅱ ) are ejected, in turn, by the cam rod and cam. ② First-step ejection When the cam passes over the adjusting pin (push pin), the cam moves to inside the cam rod, which stops ejection of the ejector plate ( Ⅱ ). ③ Second-step ejection Further ejection of the ejector plate ( Ⅰ ) adds to the amount of ejection: the difference between A and B is the amount of the second-step ejection. ④ Return distance Please note that the operation error occurs if plate ( Ⅱ ) is not operated after plate ( Ⅰ ) completely goes down.
Fixed mold plate
Stripper Plate Movable mold plate
④ Mold closing (Without early return unit)
③ Mold closing (Early return unit)
② Ejection of
①
Mold closed
ejector plates
Back up plate
■ Notes • Use the unit with the ejector leader pin, ejector leader bushing, return pin, and coil spring for returning. • Use the early return unit for ejector plate in two sets or more. • Apply grease regularly to the cam and sliding surface. • Refer to P.1191 for calculation of the buckling strength of the push pin, and use the unit with the safety rate of 3 and above. • B e sure to correctly insert the push pin into the cam rod. Incorrect insertion could damage the mold. • Incorrect selection of the length of the cam rod/bushing/push pin could cause malfunction.
Ejector plate ( Ⅱ )
Ejector plate ( Ⅰ )
Base clamping plate
② First-step ejection
① Mold opened
③ Second-step ejection
893
894
Powered by FlippingBook