Patent GB-909097-A (GB)
Title: Improvements in or relating to drilling machines
IPC: B23B39/24
Filed: 1958-01-08
Abstract: 909,097. Drilling; screwing-up screws. HOWELL & SON Ltd., BENJAMIN, and WILLIAMS, A. H. Jan. 8, 1959 [Jan. 8, 1958], No. 825/58. Class 83 (3). A machine comprises means 88 for drilling a hole in a workpiece and means 89 for inserting a screw in the hole. Boards for making a pallet or stillage are placed against an end-stop 61 on a table 31 moved on rollers 32 by a pneumatic device 39 and a chain 43 between each pair of operations and by the chain 43 and a motor 51 between holes. The boards are clamped by a pneumatic device 70 acting through equalizing linkages to move brackets 64 carrying end-clamp rollers and rubberfaced side clamps 63. Rods 36 on supports 35 carry three transversely adjustable brackets each bearing a pneumatic motor 90 rotating a drill spindle and a screwing-up spindle. Each spindle is rotated by a pulley 100 and is fed by a coaxial piston. The machine is controlled by a rotary disc valve, having axial holes therein and indexed by a ratchet mechanism, together with a control disc 132. Initially, a rod 134 is pushed axially to move a re-setting disc 131 towards the disc 132 to return trip pins 135, 136 flush with one side of the disc 132. A setting wheel 133 is then pushed in and turned until a pointer 138 coincides with the required position of a screw indicated by the scale 137, the position of the screw being read from a scale fixed to the table above the boards. A knob 139 is then depressed which causes an appropriate pin 135 to project from the disc 132. This procedure is repeated until a trip pin 135 has been set for each screw required. Finally, a limit pin 136 is set by a knob 141. Interlocks prevent the pins being reset until the discs have been returned to zero and the table is in its withdrawn position. In operation, base boards for a stillage are placed in one fixed, and two adjustable, channels 57, 58, 59, on the table 31. Cross-boards are then laid on the base boards and clamped by the device 70. The stops are set and the machine is started by a control 142. A cycle ensues with the drill being operated each time a pin 135 engages a lever 143 and ceases when a pin 136 engages a lever 144 and returns the table. In a modification, the outer tool heads 88, 89, Fig. 21, are adjusted to-and-from each other by a hand wheel 23 rotating a shaft 21 having oppositelythreaded ends engaging the heads. The table 31 is traversed by an air motor 51 rotating a shaft 49 having a brake drum 50 thereon. As in the previous embodiment, the shaft 49 carries a sprocket engaging the chain 43 attached at each end to the piston on the table 31. The piston has a stroke equal to the distance between the drills and the screwdrivers. Each pair of drills and screw-drivers is rotated by an electric motor 90. In addition to side and end clamps, the work is also held down by pneumatically-operated levers at the sides of the table. The machine cannot be started until a certain pressure has been reached in all the work-clamping cylinders. The lower limit of travel of the drilling spindle and the screwing spindle 94, Fig. 25, is signalled by a depth stop 103 which engages the work and operates a switch through a Bowden cable 502. At the upper limit of movement, a cam 503 operates a switch 505. In a further modification, the work-clamping means is operated by several pneumatic cylinders to obviate the need for the linkage.