Method and apparatus for damping of the setback in the case of rock drilling machines

摘要

1507610 Damping percussion tool recoil ATLAS COPCO AB 18 March 1976 [18 March 1975] 10981/76 Heading B4C In a percussion tool comprising a housing 10, a hammer piston 13 and a work tool 18, the recoil of the work tool is damped by retard piston 36 and fluid, preferably compressed air, in cushioning chamber 40, the fluid being supplied to the chamber via passages 30, 37. The feeding force applied and/or the pressure in passages 30, 37 are regulated so that retard piston 36 is maintained out of axial contact with the housing. Rotary-percussive action.-Tool 18 is rotated by chuck bush 31 in which its shank is displaceably and non-turnably guided; bush 31 is similarily guided in chuck 34 which transmits the rotation of gear 33 and motor 32. Bush 31, cylindrical portion 35 and annular retard piston 36 comprise a single member which is axially journalled on the air in cushioning chamber 40. Bush 31 is pressed against a collar on tool 18 to transmit a feeding force. Piston 13 comprises rods 14, 15 guided in bushings 16, 17 (the bushing 16 also serving to guide the inner surface of annular retard piston 36) and an enlarged drive head situated between rods 14, 15 in drive chamber 12, the lining 11 of which is spaced from the piston drive head. An annular valve 20 reciprocates between a forward position shown in which it allows oilfree compressed air from fitting 21 to flow via passages 23, 24 and inlet openings 29 to the front of drive chamber 12 to return the piston, and a rear position in which air passes via annular chamber 22 and annular groove 27 to the rear of chamber 12, see Specification 1,462,333. Oil-carrying compressed air is supplied-via fitting 28 to passage 30 to lubricate bushing 16 and-to pressurize cushioning chamber 40. Fluid to flush the tool 18 is supplied via a tube 19 extending through hammer piston 13.