Improvements in or relating to marking or centre punches

Abstract

Abstract 847,396. Percussion tools. NATIONAL RESEARCH DEVELOPMENT CORPORATION. Aug. 28, 1958 [Aug. 30, 1957], No. 27359/57. Class 124. A fluid operated tool for marking or centre punching comprises a cylinder 1 having mounted at one end the marking punch 15, Fig. 1, or centre punch 37, Fig. 6, and at its other end a valve mechanism 18 which is operated by the relative sliding movement between the cylinder 1 and an outer sleeve member 7 when the punch is pressed against the workpiece, the valve mechanism 18 controlling the inflow and exhaust of pressurised fluid to and from the interior of the cylinder to operate a piston 5 which delivers the blow to the punch. The valve mechanism is in the form of a piston valve 18 slidably mounted within a plug assembly 3 which closes one end of the cylinder 1. The piston valve 18 is formed with a pair of annular grooves 25, 26. The groove 25 forms together with ports 27, 28, 30, 31, Fig. 1, the communication between a pipe line 29 which supplies pressurised air and the interior 4 of the cylinder 1 when the valve 18 is moved into its forward position against the action of a spring 22 by the forward sliding movement of the sleeve 7 relative to the cylinder 1. The groove 26 forms together with ports 32-35, Fig. 4, the communication between the interior 4 of the cylinder and atmosphere when the valve is allowed to return to its retracted position by the spring 22. The forward end of the cylinder 1 is closed by a plug assembly 2 having a tubular part 9 which receives the shank 11 of the punch. The shank 11 extends into the path of movement of the cylinder piston 5. A return spring 16 is provided between the piston 5 and the plug 2. The marking punch 15, Fig. 1, has a distance piece 13 between a shoulder 12 on the shank 11 and the inside of a hollow nut 14 screwed on to the part 9. In the centre punch 37, Fig. 6, the shoulder 12 rests against the inside of the hollow nut 14 and a spring 39 is inserted between the part 9 and the shoulder 12.

Inventors

• 👤 Derek Alfred Hutton-Williams
• 👤 Peter John Shepherd

Bibliographic Details