We all know that products with undercuts require a mold structure to eject them. Generally, internal undercuts are handled with a slanted ejector, while external undercuts are handled with a slider. Another situation involves a forced ejection mechanism. When an internal undercut cannot be handled with a slanted ejector, what structure do we use? See the diagram below:
Image 1. For this type of product, a slanted ejector is not possible; the only option is to use an internal slider core-pulling mechanism for ejection. The internal slider core-pulling mechanism consists of an internal slider, a chuck, and a pressure plate.
Image 2. Design scheme for the internal slider
Image 3. The motion principle of the internal slider mechanism:
(1) For this type of internal slider mechanism, a support plate must be added to the bottom of plate B. Plate B and the support plate must be able to open, and the chuck is locked onto the support plate.
(2) First, plates A and B are opened. After opening to a certain distance, plates B and the support plate are then opened. The opening distance is controlled by limit screws. Since the shovel is locked onto the support plate, it moves in the direction of the arrow. There is a dovetail groove between the inner slider and the shovel. Due to the action of the dovetail groove, the two inner sliders are driven to slide inward (in the direction of the arrow), disengaging from the undercut and completing the core pulling.
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