Patent GB-795328-A (GB)
Title: Improvements relating to a machine for dressing tools such as drilling bits
IPC: B21K5/06
Filed: 1956-05-24
Abstract: 795,328. Sharpening drills by forging; trimming dies. STARDRILL - KEYSTONE CO. May 24, 1936 [June 2, 1955], No. 16082/56. Class 83 (4). A machine for dressing tools such as well drilling bits, by forging, comprises a dressing die 25, means for advancing the tool relatively to the dressing die, a dressing member 63 pressed towards the dressing die, and means 69 for moving the dressing member transversely of the axis of the dressing die. The latter comprises a set of gripping die members 25, Fig. 4, movable by transversely acting means 20, 21 from an open inoperative position, Fig. 3 (not shown), to a closed operative position in which the die members grip the tool to be dressed positioned therein. The machine is mounted on a chassis 2, Fig. 1, having fourtyred wheels 4 and which may be self-propelled or be towed through a connector by an automobile truck. The die halves 25, Fig. 4, are pivoted at 26 and connected by links 31 to a cross-head 38 slidable in a vertical frame 13 by a fluid pressure motor 20, 21. The tool to be dressed 108, Fig. 12, has an adaptor 107 screwed to its rear end and the cutting end of the tool is then heated to forging temperature. The tool is moved into the machine by a hoist 76, Fig. 1, and the adaptor flange 106 is engaged within a recess 105 of a connecting member 104 secured to a piston 102 working in a cylinder 101. The latter is mounted on a carriage 99 slidable longitudinally of the chassis 2 by means of a pair of lead screws 77 driven through toothed and chain gearing, Figs. 13, 14 (not shown), by a fluid pressure motor or by hand. A latch 110 is then moved manually by toggle linkage 114, 116 to engage over the tool adaptor 107 and lock it within the recess 105. The carriage is then moved to the left, Fig. 1, to push the tool 108 through trimming die halves 43, Fig. 6, and the die halves 25, both of which are open. The cross-head 38 is then lowered to close both sets of dies, which are connected together for simultaneous operation, around the tool. Wedge projections 35, 46 at the top of the dies are engaged by wedge-shaped recesses 37, 47 in the cross-head 38 to lock the dies in their closed position. The cutting edge of the tool is then dressed by a roll 63 having a central annular dressing groove 64, Fig. 5 (not shown). The roll is freely rotatable in a pair of parallel links 60 pivoted on a horizontal shaft 57 mounted in end shoes 58 for movement longitudinally of the chassis and connected to the piston rod 54 of a fluid pressure motor 50. The latter presses the roll 63 against the edge of the tool and the roll is then oscillated about the shaft 57 by a vertical fluid pressure motor 69 whose piston rod 68 is connected at 66 to lugs 65 of the parallel links 60. During dressing the tool may be pressed to the left by movement of the carriage 99 or, if greater force is required, by admitting pressure fluid to the right of piston 102, Fig, 12. After dressing the tool may be partially withdrawn by admitting fluid to the left of piston 102 whereupon the dies 25, 43 are opened and the dressed end of the tool withdrawn, by movement of carriage 99, out of die 25. The trimming die 43 is again closed and the dressed tool end is then drawn through the trimming die to trim off any flash, by operation of the piston 102. In another embodiment, Figs. 15, 16 (not shown), the dressing die is in four parts comprising a fixed lower member, two opposed movable side members and an upper movable member, the side and upper members being linked together for simultaneous movement. A petrol engine 121, Fig. 1, drives a pump 122 for supplying hydraulic fluid to the various motors.