GB1011279A - Improvement in feeding device working in stepwise manner for a rock drill - Google Patents

Abstract

1,011,279. Rock drills. ATLAS COPCO A.B. April 8, 1964 [April 16, 1963], No. 14503/64. Heading B4C. [Also in Division F1] A feeding device 20 for a rock drill 68 comprises a feed bar 45 for slidably supporting the drill, a pair of locking members 44 movably mounted on the bar, a fluidpressure operated motor 21, 22 having co-operating piston and cylinder elements coupled one to each locking member, and first and second reversing elements 50 movably mounted on the motor each adjacent a locking member, the elements being movable from a first position wherein the locking members provide unidirectional locking against the feed bar to allow forward and prevent rearward movement of the members along the bar to a second position wherein the members provide unidirectional locking against the feed bar to allow rearward and prevent forward movement along the bar. The piston 22 is mounted on a rod 27 which has a collar 32 and shoulder 33 respectively engageable with a sleeve valve 30 at the ends of the stroke of the piston in the cylinder to move the sleeve valve and reverse the connection of fluid pressure supplied from a conduit 35 to the ends of the cylinder, the sleeve valve having an annular groove 40 which alternately communicates with a passage 48 leading to one end of the cylinder and an exhaust passage 38, the conduit 35 being alternately connected to the groove and a port 39 leading to the other end of the cylinder. Both the rod 27 of the piston and a rod 41 extending from the cylinder carry a locking member 44 on a pivot 43. Each locking member consists of a plate having slots 47 which engage the flanges 46 of the feed bar 45 and each locking member is associated with a reversing element 50 consisting of a housing which is rockable on its respective rod 41, 27 and houses a pair of plungers urged by springs into engagement with the associated locking member. The sides of the locking members facing the reversing elements are formed with recesses 58, 59 which are less than 180 degrees apart so that when the housing is rocked between limit positions determined by a pin 27 engaging a slot in the housing one or other of the plungers is aligned with a recess and the locking member is inclined in one direction or the other to effect unidirectional locking in one direction or the other. The housings are rocked by levers 60, that lever on the forward housing mounted on the rod 41 having a strut 62 passing under the rod on the other housing. The rod 41 carries plates 74 engaging rubber buffers 73 disposed one each side of a plate 71 upstanding from a slide 65 which, by means of a pivot 67 carries a hammer-type rock drill 68 having a drill 67 extending through a guide 70 at the front of the feed bar. A cam 83 is adjustably mounted on the feed bar for engagement by the rod 60 or strut 62 of the forward reversing element. In operation, fluid pressure is supplied through a valve 79 and conduit 80 to the drill 68 and a tapping 82 leads to the conduit 35 connected to the fluid motor. With the reversing elements in the position shown in Fig. 5, continuous contraction and expansion of the motor causes the locking elements to move step-by-step along the feed bar and advance the drill step-by-step. At the end of the forward feed, the cam 84 is engaged by the bar 60 or strut 62 to rock both reversing elements 50 so that their other plungers engage their associated recesses and incline the locking elements in the opposite direction, the continuous extension and contraction of the motor reversing the direction of movement along the feed bar until the rod 60 actuates the valve 79 to cut off the supply of pressure fluid to the motor.