Latching device for injection molding dies

A latching device for releasably latching together two die halves of an interchangeable injection molding die of an injection molding machine, which die halves are openable and closable along a longitudinal movement axis determined by a die closing unit of the injection molding machine, the die closing machine having two die carrier means to which the two die halves are attachable, and the closed die halves having axially inner sides abutting against each other in a die separation plane which is perpendicular to said movement axis, the latching device comprising in combination:

• at least one guide sleeve mounted in an axially oriented bore of a first one of the two die halves, each guide sleeve having a length portion in the form of an outwardly cylindrical guide portion protruding axially beyond said die separation plane;
• an equal number of guide bushings mounted in the second one of the two die halves, each of said guide bushing located in a bore which is axially aligned with a bore and guide sleeve of the first die half, each guide bushing having a guide bore which cooperates with the guide portion of a guide sleeve in the first die half to provide a centering and guiding function for the two die halves, as the die halves execute opening and closing movements while attached to said die closing unit;
• a shoulder defined by the guide bushing, the shoulder being located radially outside said guide bore and facing away from the die separation plane;
• a latching plunger arranged in at least one guide sleeve so as to extend axially therethrough and to be axially movable in relation to the guide sleeve between a latching position and a release position, the release position being closer to the second die half, the latching plunger having inner and outer axial extremities;
• a plunger spring biasing the latching plunger in the direction towards the latching position;
• a drive head on the outer axial extremity of the latching plunger, the drive head being engageable by the die carrier member to which the first die half is attachable and so positioned in relation to said die carrier member that the attachment of the first die half to said die carrier member causes the drive plunger to be moved to the release position, in opposition to said plunger spring;
• a latching head on the inner axial extremity of the latching plunger extending axially inwardly beyond the guide portion of the guide sleeve;
• a latching member axially confined between the latching head of the latching plunger and the inner extremity of said guide portion of the guide sleeve, the latching member being shiftable between a rest position in which the latching member is located entirely within the diameter of the guide bore and a latching position in which the latching member reaches radially beyond said diameter to engage the shoulder of the guide bushing, thereby preventing the separation of the two die halves by preventing the axial withdrawal of the latching plunger, the latching member being spring-biased towards the rest position;
• and
• means defined by the latching head and the inner extremity of the guide portion of the guide sleeve for shifting the latching member from the rest position to the latching position, in opposition to the latching member spring bias, when the latching plunger is moved from the release position to the latching position by said plunger spring.