Patent GB-472044-A (GB)
Title: Improvements in and relating to metal milling or boring machines
IPC: B23Q35/18
Filed: 1936-03-10
Abstract: 472,044. Milling - machines ; fluid servomotor controls. FITZPATRICK, H. J. (Clearing Machine Corporation) March 10, 1936, No. 7184. [Class 83 (iii)] [Also in Group XXIX] In adapting a vertical-spindle knee-type milling or boring machine for copying, the nut co-operating with the screw for raising and lowering the knee is made slidable in its support and the knee movements are derived from fluid pressure cylinders under the control of a tracer-operated valve, the screw being used to adjust the knee beyond the range of movement of the cylinders. The screw and fluid pressure operation of the knee may be effected independently. The outer knee screw 15, Fig. 6, screws in an adaptor 20 slidably keyed in the fixed support 16 and the inner screw 14, which screws in the screw 15, is rotatable by bevel gearing 17 and a handoperated shaft 19, Fig. 1. Brackets 29 are attached to the knee 5 and rest on shoulders on piston rods 27 actuated by pistons in cylinders 24, fluid being supplied below the pistons by pipes 36, 37 and a pump 32 driven by a motor 33. When the pistons have reached their uppermost positions, or at any intermediate point, the fluid below them may be trapped by closing a hand-operated valve 35 and the knee raised further by rotating the hand-wheel shaft 19. This rotates the screw 14 within the screw 15, pushing downwards the screw 15 and adaptor 20 until a flange 141 on the screw 14 engages the top of the bore in the screw 15. The screws 14, 15 then rotate together and move the adaptor 20 downwards until it engages the bottom f of the support 16 whereupon further rotation of the shaft 19 raises the knee. The brackets 29 on the knee then slide on the reduced portions of the piston rods 27 until they engage adjustable limiting stops 31 on the rods. Copying-mechanism.-The supply pipe 36, Fig. 1, from the pump 32 to the cylinders 24 has a branch 34 leading by a flexible pipe 39 to the stationary tracer cylinder 40. A tracer 49 is attached to a piston 46 within the cylinder and arranged either to shut off the pipe 34 from the cylinder or to connect this pipe by variable amounts with an exhaust pipe 43 leading to a sump 45. A telescopic portion 44 is included in the pipe 43. The work 10 is mounted on a table 8 movable oii transverse ways 7, 9 on the knee 5, and the pattern 50 is mounted on an extension 51 of the table. When the tracer is out of contact with the pattern, the pipe 34 is closed by the piston 46 and the cylinders 24 receive the full pressure of the pump, thereby raising the work towards the cutter 12. Engagement of the pattern with the tracer raises the piston 46 and allows fluid to escape from the pipe 34 to exhaust, thus lowering the pressure in the cylinders 24 and slowing, stopping or reversing the motion of the knee 'and work towards the cutter in accordance with the shape of the pattern. Downward movement of the work is produced by the weight of the knee, table, &c. The work and pattern are traversed past the cutter and tracer by feeding the table 8 on the ways 9 by means of a hand-operated screw (not shown). Fluid dripping from the cylinder 40 is collected in a tray 52 and conducted to the sump 45 by a pipe 53, and a vent pipe 78 leads from the upper ends of the cylinders 24 to the sump. Tracer-mountings.-The tracer cylinder 40, Figs. 1 and 3, is vertically adjustable by slots and screws 76 on an arm 74 horizontally adjustable in a clamp 73 on a rod 72 adjustable at right angles to the arm 74 in a clamp 71 on a bracket 70. The bracket is attached to the vertical column 3 which supports the knee 5 and the driving gearing 13 for the cutter spindle. Gauging-devices ; limiting depth of cut.- Upward feed of the knee is limited by a collar 58, Figs. 1 and 3, on a rod 54 attached to the knee 5, engaging a lever 59 pivoted on a standard 60 secured to the bracket 70. The lever 59 is held by a spring in contact with a circular tappet 61 on a lever 62 pivoted at 65 on the bracket 70. An extension 66 is adjustable about a vertical axis 66<1> on the lever 62 and carries a telescopic extension 68 engageable with a collar 69 on a rod 56 attached to the tracer piston 46. Upward motion of the collar 58, beyond a predetermined point raises the piston 46 and connects the pipe 34 to exhaust, thereby stopping further upward movement of the knee.