Patent GB-380091-A (GB)
Title: Improvements in and connected with apparatus for drilling metal tubular members
IPC: B23B47/18
Filed: 1931-06-09
Abstract: 380,091. Drilling-machines. VICKERS (AVIATION), Ltd. and WALLIS, B. N., Weybridge Works, Byfleet Road, Weybridge, Surrey. June 9, 1931, No. 16763. [Class 83 (iii).] In apparatus for making tubes from semicylindrical strips of sheet metal held together with their edges overlapping, particularly for use as aeroplane spars, the strips are clamped in position on a mandrel supported on a carriage which is given an intermittent traverse by an escapement mechanism past two opposed drill heads for drilling the rivet holes in the seams. The machine bed comprises channel members 11 supported on legs 12 and the drills 23, Fig. 4, are driven by electric motors 24 supported in brackets 25 slidable on sleeves 26 which are screwed into brackets 27 attached to the members 11. Pins 130 on the brackets 25 engage slots in the feed levers 31 which are pivoted at 32 and carry rollers 42 engaging a cam 54 on a shaft 39 rotated by a hand-wheel 38. Springs 41 normally tend to retract the drills. Actuation of the machine is prevented by a plunger 91 forced into engagement with a groove 90 in the hand-wheel 38 by a spring 92 until the plunger is withdrawn by a pedal 96 acting through a link 95 and lever 93, and rotation of the wheel is confined to one direction only by a pawl 89 engaging a ratchet 88 on the wheel. Slides and carriages ; spacing mechanism; work, gripping and mounting.-The strips 20, Fig. 4, are secured at the ends by circular clamps to a mandrel 18, Figs. 1 and 4, having squared ends 17 passing through slots in brackets 43 attached to a carriage 15. Clearance is left between the mandrel and brackets 43 so that the mandrel may be tensioned by nuts 19 to prevent sagging thereof and slots 22 are provided to allow the drills to pass through the work. The carriage is slidable longitudinally on rollers 14 carried by transverse shafts 13 and is guided by inclined rollers 16, Figs. 3 and 5. A rack 33 is attached to the carriage and is held stationary whilst the drills are operating by a pawl 37 on an arm 69 secured to a shaft 71. When the drills have withdrawn a cam surface 74, Fig. 4, on the cam 54 engages a roller 73 attached to the arm 69 and moves the pawl 37 transversely, releasing the rack and allowing a weight attached to a pulley 34 to draw the carriage forward a distance equal to half the pitch of the rack teeth, a second pawl 68 on the cam 69 then engaging the tooth which the pawl 37 has left. On passing off the cam 74, the roller 73 is released and a spring 77 returns the pawl 37 into engagement with the next tooth of the rack, the weight having moved the carriage through another half pitch distance. The arm 69 is maintained by a spring 79 in contact with a plate 80 capable of transverse movement by a disc 86 attached to a shaft 83 screwing in a hole 85 in the member 11. Inclined slots 81 in the plate 80 engage the heads of stationary bolts 82 so that on rotation of the shaft 83 by a hand-wheel 78 the plate will be moved forwardly or rearwardly to locate the work in the exact position for receiving the holes. Should it be desired to advance the work through one or more pitch distances without drilling holes therein a handle 110, pivoted at 111, may be reciprocated to give the arm 69 one or more spacing motions through a collar 171 on the shaft 71 engaging a cam end 113 on the lever. A spring 112 returns the lever. At the end of its transverse the carriage 15 engages a block 97, Fig. 1, secured by bolts to a second block 97 attached to the machine frame, rubber blocks 100 being mounted between the blocks 97. Jigs.-The drills 23, Fig. 4, are guided by bushes 30 carried by pins 28 which screw into the sleeves 26 and are locked therein by nuts 29 to adjust the bushes in proximity to work of different diameters. Specification 380,093 is referred to.