Patent GB-582762-A (GB)
Title: Improvements in or relating to drilling machines
IPC: B28D5/02
Filed: 1943-11-29
Abstract: 582,762. Drilling diamonds &c. DEFENSE SUPPLIES CORPORATION. Nov. 29, 1943, No. 19942. Convention date, Oct. 12, 1942. [Class 83 (iii)] [Also in Group XXIII] A machine for drilling hard substances such as diamonds comprises a vertical drill spindle mounted above a vertical work-holding spindle means to effect a separation of the work and drill at regular intervals, means for advancing a grinding-wheel to true the point of the drill whilst out of drilling position, means for compensating for the wear of the drill when returning it to drilling position and means for rapidly reciprocating the work spindle through a small amplitude during the drilling interval. Each drill spindle 1, of which any desired number may be mounted in a frame comprising end plates 7 connected by crossrails 8a, 8b, 8c and a baseplate 6, is moulded in bearings 50, 51 secured to the rails 8c, 8b, and is driven by a belt 54 passing over jockey pulleys 55a, 55b from a driving pulley 53 on a shaft S<1> driven by a belt 9 from a motor (not shown). Shafts S<2>, S<3>, S<4> and S <5> are driven from the shaft S <1> by belt, spur and chain gearing. The speed of the shaft S<4> controls the frequency of a complete drilling and grinding cycle, whilst the speed of the shaft S<3> controls the relative lengths of drilling and grinding time in each cycle. Each work spindle is driven'by a belt 35 from the shaft S<2>, is mounted in bearings 28, 30 and carries a face-plate 45 recessed to receive a holder 46 containing the diamond to be drilled, particularly for the production of drawing- dies. The reciprocation is imparted to the drill spindle by a lever with an arm 20 engaging the pulley 23 and arm 21 engaging an eccentric 38 on the shaft S<2>. The drill spindle is raised from drilling-position by a plate 78 engaging a collar 81, and having a boss 80 secured by a grubscrew to a rod 76 guided in the rails 8b and 8c and carrying a block 75 adjustably secured at 77 and resting on a pin 73 carried by a lever 70 pivoted at 68 on a plate 58 secured at 60 to a rod 59. The lever 70 is linked at 71 to a rod 123 connected to a bracket 122 supporting the motor 116 on the shaft 117 on which the grinding-wheel 118 is mounted. The movement of the lever 70 is limited by stops 82, 83. Guide rods 100, 101 passing through the rails 8b, 8c are secured to a frame 99 carrying the pulleys 98 and this frame is adjustably suspended by a screw from a block secured to a rod 90 secured at 91 to the plate 58. One side bar of the frame 99 extends under the plate 78 and the frame 99 rather than the stop 83 controls the lower position of the drill spindle,. the upper position being limited by the stop 82. Parallel bars 111 secured in the rail 8a are connected at their other ends by a strip 110. A carriage 115 slides on the bars 111 and supports a strip 190 pivoted at 191 and having an upstanding part 192 co-operating with a clamp 193 secured to the carriage by a bolt 196. A stop 197 on the strip engages an adjusting screw 198 carried by an upstanding wall 200 of the carriage. The motor 116 is carried by the strip 190 and by means of the screw and clamp may be swung laterally to vary the contour imparted to the point of the drilling-needle. The carriage is traversed by a connection 134 extending from the guide lug 132 to a sleeve 135 in which is secured by a pin 138 on the rod 136 of the strap 139 of an eccentric 142 on the shaft S<3>. A stop 127 in a bracket 122 of the carriage receives a sleeve 128, with a flange 125, loose on the rod 123 as limited by end nuts 121 and a spring 124 engaging a collar 126 fast on the rod. Traverse of the motor into grinding position therefore slides the rod 123 through the spring 124 and thus lifts the plate 78 and with it the drill spindle. As the carriage nears the grinding position, an arm 149 on a sleeve 148 with a spring mounting closes a switch 145 to start the rotation of the motor, and as the carriage retreats from the grinding-position the arm 149 is moved away allowing the switch to open and stop the motor. The eccentric 142 is loose on the shaft S<3> and carries a pin 160 turnable by a lever 161 so that a reduced end may either engage or be free of one of a number of recesses 169 in a sleeve fixed on the shaft S<3>. As the carriage approaches the end of its traverse on bringing the grinding-wheel away from the drill, the lever 161 engages the end of a trip lever 162 and disengages the clutch. Drilling then continues until a tappet 166 carried by the shaft S4 trips the lever 162 allowing a spring 168, Fig. 4, to re-engage the clutch. Tappets 182 carried by the shaft S<5> rock, through an adjustable arc, a spring- controlled plate 65 carrying a pawl 64 to give a part rotation to a ratchet-wheel 63 on a sleeve tapped at 62 to engage the threaded end 61 of the rod 59, and so lowers the plate 58 and attached. rod 90 and supported frame 99 step by-step. The drill spindle is thus advanced a little further towards the work after each grinding of the drill. Belt tension is maintained by the jockey pulley 55b which is mounted on a spring-controlled arm 201. The pulleys- 98 are vertically adjustable on the frame 99 at 208 and the belt 54 slopes upwardly away from the pulley so that the full tension counteracts to some extent the weight of the drill spindle and enables the pressure of the drill on the diamond to be varied. Specification 582,763 is referred to.