Reversing mechanism for safety gate of injection molding machine

A safety gate control mechanism for a production machine having a safety gate which is movable between open and closed positions by means of a safety gate drive with a drive control circuit, which control mechanism interrupts a closing movement of the safety gate, when the safety gate encounters an object or obstacle in its closing path, said safety gate control mechanism comprising in combination:

• a straight leading edge on the safety gate extending transversely to the path of the closing movement of the safety gate;
• a pivotable straight contact bar extending parallel to and ahead of said leading edge of the safety gate, the contact bar being attached to the safety gate by means of a pivot connection defining a contact bar pivot axis which is likewise parallel to the leading edge of the safety gate;
• means for biasing the pivotable contact bar forwardly away from the leading edge of the safety gate into a rest position from which an obstacle in the path of the closing safety gate causes the contact bar to pivot rearwardly towards said leading edge, in opposition to said contact bar biasing means;
• and
• switching means in the drive control circuit of the safety gate drive for interrupting the closing movement of the safety gate, in response to a rearward pivoting movement of the contact bar;
• and wherein:
• the pivotable contact bar includes a wall portion with a curved surface corresponding substantially to a sector of a cylinder around the contact bar pivot axis, said curved surface having a rearwardly pointing extremity defining a trigger edge;
• the switching means includes an electrical switch with a depressible switch plunger, the switch being mounted on the safety gate, behind its leading edge, and so oriented that the axis of the switch plunger is perpendicular to the contact bar pivot axis;
• and
• the switching means further includes an actuating lever which is pivotably supported by the safety gate on a pivot axis which is parallel to the contact bar pivot axis and located between the contact bar pivot axis and the trigger edge of the contact bar in rest position, the actuating lever being movable between a rest position and a pivoted position and having a first extremity cooperating with the switch plunger to depress the latter, when the actuating lever is pivoted out of its rest position, and a second extremity which, in the rest positions of the actuating lever and of the contact bar, extends into the the path of said trigger edge of the contact bar in the immediate vicinity of said trigger edge, overlapping its pivoting path by such a radial depth that, when the contact bar is pivoted rearwardly, its trigger edge cooperates with the second extremity of the actuating lever to pivot the actuating lever and to thereby depress the switch plunger.