GB946189A - Improvements in or relating to hydraulic drill feed control - Google Patents

Abstract

946,189. Rock drills. ATLAS COPCO A.B. July 16, 1962 [July 20, 1961], No. 27178/62. Heading B4C. [Also in Division F2] A high-pressure fluid feed control for a drill rig mounted rock drill 31 having a fluid-driven rotary motor 33 for rotating the drill steel 34 and arranged to be fed by a fluid-driven motor 43 along guides 26 on the rig, comprises a high-pressure pump 45 having means 63, 65, 71 for varying its displacement, and connected to the feed motor, there being pressure fluid-actuated means 75 responsive to a selectively preset pressure and associated with the varying means for automatically reducing the displacement of the pump to a value according to the requirements of the drilling performed when the preset pressure is exceeded. The guides 26 for the rotary motor 33 are formed on a structure 25 pivotally mounted on a forked frame 18 itself pivoted on a base frame 10. The pump 45 for the feed motor 43 is mounted within a reservoir tank 47 mounted on the frame 10. A second pump 44 for driving the rotary motor 33 is mounted in a tank 47 on the frame, both pumps being rotated by means of an electric motor 46 or an internal combustion engine. The pumps are of the axial piston-type having a driving plate normal to and fixed to the driving shaft, the cylinder barrel and piston assembly being mounted in a housing 44<SP>1</SP>, 45<SP>1</SP> which is pivotally mounted in bearings 48, Fig. 6, in order that the inclination of the cylinder barrel may be varied and thus adjust the displacement of the piston. The means for automatically varying the displacement comprises a piston-and-cylinder device 63, 71, 55, the ends of the piston being acted upon via pipes 56, 73, by the output pressure from the pump. As shown in Figs. 6 and 7, a piston operated valve 75 communicates with the cylinder 72 for the piston 71 and is connected via a pipe 60, pre-set valves 58, 59 and non-return valve 57 with the inlet and outlet pipes from the feed and rotary drill motors 33, 43. In the event of the drill jamming the excess pressure in the latter pipes opens the valves 58 or 59 and acts on the piston valve 75 to thereby exhaust the pressure via a passage 78, from the cylinder 72 and so reduce the output from the pump. Reversing valves 53 are provided for the motors and interconnected slide valves 54 are provided for either connecting the output from the pump to the motors, or to drive motors 15 or to the reservoirs 47. The pumps may also be connected to rams 20 and 27 for adjusting the position of the structure 25 and the rams 14 for stabilizing the frame 10. Tracks 13 are also driven by means of hydraulic motors 15 via a gear 16.