GB336004A - Improvements in or relating to punching or drifting machines - Google Patents

Abstract

336,004. Holman, A. T., and Holman, K. J., and Rule, J. July 9, 1929. Percussive drills.-A drift 32 for enlarging the bores of hollow drill steels and similar articles is attached to an anvil member 7 which carries two anvil blocks 9, 10, the latter being in two parts held together by the bore 12 in the cylinder 4. The whole is mounted on the bar 13 which moves longitudinally on rollers 2, 3. Notches 26, 27 are formed in the bar to engage the rollers and so retain the machine in its rearmost position when subject to vibration. On pulling the handle 20 to the left the drift is brought into contact with the work, and the anvil member is forced into its rearmost position within the cylinder 4. A further pull on the handle moves the tappet sleeve 18 to the left, opening the valve 17. Pressure fluid then enters the cylinder, causing the piston 8 to strike the anvil block 9. Due to the position of the anvil member relative to the cylinder and its parts the return stroke of the piston is cushioned from the anvil block 10. On releasing the handle 20 springs 118 return the tappet sleeve to its central position and the valve 17 is closed, stopping the piston. To withdraw the drift, handle 20 is pushed to the right, first moving the cylinder rearwardly relative to the anvil member, and then depressing the valve 17. The piston now strikes the anvil block 10, its blows on the block 9 being cushioned.