Work locating apparatus

Abstract

A work locating apparatus having a tension member actuated by an actuating member, particularly an actuating piston, via a starting stroke and a working stroke in which a pneumatic cylinder constitutes a control means and a mechanical step-up mechanism is operable between the control means and the tension member with the actuating member abutting directly the tension member by the starting stroke and the step-up mechanism by the working stroke of the tension member.

What is claimed is: 
     
       1. A work locating apparatus having a tension member actuated by means of a piston movable within a cylinder, particularly a pneumatic cylinder, via a starting stroke and a working stroke, in which said tension member is actuated with an amplified force by a mechanical step-up mechanism during the working stroke whereby said piston becomes releasable from said tension member and said piston actuates on the one hand, said tension member directly via said starting stroke and on the other hand, said step-up mechanism via said working stroke, the improvement comprising swinging levers hinged on said tension member, each lever being provided with an abutment portion and a guide portion, said abutment portion being guided along the cylinder wall during the starting stroke, a collet coaxial with said cylinder, said piston being connected to said collet, said collet having wedge-shaped outer surfaces which cooperate with said guide portion of said swinging levers, and said cylinder being provided with an abutment surface positioned transversely to the axis of the cylinder with said abutment portions of said swinging levers being pressed against said abutment surface during the working stroke. 
     
     
       2. The work locating apparatus as claimed in claim 1 in which the piston is defined by an annular piston, a central piston encircled by the annular piston, whereby said central piston is connected with the tension member, and said collet encircling the center piston. 
     
     
       3. The work locating apparatus as claimed in claim 2 in which the central piston is provided with a recess into which the guide portion of the lever, which lever is located at a distance from the rotation axis, may evasively move as long as that part of the lever defining the abutment portion contacts the inside wall of the cylinder, whereby the front edge of the collet engages the guide portion during the starting stroke and the cylinder being provided with an enlarged area, which is delimited axially at the side nearest to the annular piston by means of the abutment surface, and the abutment portion of the lever at the completion of the starting stroke enters the enlarged area, whereby the guide portion of the lever is moved to the wedge-shaped outer surface of the collet. 
     
     
       4. The work locating apparatus as claimed in claim 3 in which the front edge of the collet engages a contact area of the guide portion, said guide portion being tilted radially outwardly at the end of the starting stroke. 
     
     
       5. The work locating apparatus as claimed in claim 1, in which said wedge-shaped outer surfaces of said collet constitute a conical surface. 
     
     
       6. The work locating apparatus as claimed in claim 1, including a pressure means which transmits the tension power and in which the pressure means is provided with a connector thread for receiving a selectively attachable connection member. 
     
     
       7. The work locating apparatus as claimed in claim 1 in which the part of the lever defining the abutment portion is formed according to a sliding curve. 
     
     
       8. The work locating apparatus as claimed in claim 1 in which a pressure means which transmits the tension power, is supported against the tension member by means of interpolation of a spring means. 
     
     
       9. The work locating apparatus as claimed in claim 8 in which the pressure means is fixedly connected with the central piston. 
     
     
       10. The work locating apparatus as claimed in claim 8 in which the pressure means is carried in the tension member via a piston. 
     
     
       11. The work locating apparatus as claimed in claim 3 in which the abutment surface is arranged at a sloping angle to the stroke direction in the axial direction of the cylinder whereby said abutment surface is of a flat conical shape. 
     
     
       12. The work locating apparatus as claimed in claim 11 in which the abutment surface merges with a rounded intermediate section into the inside area of the cylinder. 
     
     
       13. The work locating apparatus as claimed in claim 1 in which the part of the lever defining the abutment portion is provided by a roller positioned in the lever. 
     
     
       14. The work locating apparatus as claimed in claim 3 in which the tension member is of cylindrical shape, and the enlarged area being located in a first collar, said enlarged area being circular and being provided with a connecting means for a pressure supply. 
     
     
       15. The work locating apparatus as claimed in claim 3 in which the enlarged area of the cylinder is defined as a circular space and the recess of the central piston is defined as an annular tee-slot and a plurality of swinging levers being evenly distributed about the circumference of the central piston and being positioned in the tension member. 
     
     
       16. The work locating apparatus as claimed in claim 15 in which the tension member is supported near the pivotal points of the levers against the cylinder, with the tension member being provided with a third collar which is circular, said tension member being guided in the cylinder by said third collar. 
     
     
       17. The work locating apparatus as claimed in claim 3, in which the guide portion is defined by a roller positioned in the lever. 
     
     
       18. The work locating apparatus as claimed in claim 2 in which the central piston is provided with a second collar which is placed on the central piston. 
     
     
       19. The work locating apparatus as claimed in claim 18 in which the second collar is spring biased towards the annular piston. 
     
     
       20. The work locating apparatus as claimed in claim 3 in which the tension member encircles the central piston to provide an annular recess which enables the insertion of the collet. 
     
     
       21. The work locating apparatus as claimed in claim 2 in which the collet is provided with an outwardly inclined section merging with a cylindrical section, the cylindrical section merging with a second outwardly inclined section and an inwardly inclined section merging with said second outwardly inclined section. 
     
     
       22. The work locating apparatus as claimed in claim 2 in which the bottom of the cylinder is provided with a ring of a plastic material, providing an elastic mounting for the annular piston.