We all know that products have undercut, usually, the inner undercut of the product is generally released by a lifter, and the outer undercut of the product is released by a slider. When the inner undercut of the product cannot be used as a lifter, what structure do we use? 

As shown below:

Encounter this type of product, can not do lifter, can only consider the inner slider core pulling. The inner slider core-pulling mechanism is composed of an inner slider, a wedge, and a guide block.

Design scheme of inner slider

Movement principle of inner slider mechanism:

(1)For this type of internal slider mechanism, a support plate must be added to the bottom of the B plate, and the B plate and the support plate must be able to be opened. The wedge is locked on the support plate.

(2)Firstly, A plate and B plate is opened, after opening to a certain distance, then the B plate and the support plate is opened. The opening distance is controlled by a limit screw. As the wedage is locked on the support plate, the wedge moves in the direction of the arrow , there is a dovetail groove between the inner slider and the wedge. Due to the effect of the dovetail groove, the two inner sliders are driven to slide inward (in the direction of the arrow), disengaged from the undercut, and the core pulling is completed.