Patent GB-471108-A (GB)
Title: Improvements in or relating to a copying metal cutting machine
IPC: B23Q35/36
Filed: 1936-01-27
Abstract: 471,108. Hydraulic transmission of power; fluid - pressure servomotor - control systems. KAIN, C. H. Jan. 27, 1936, No. 2563. [Classes 69 (ii) and 135] [Also in Group XXII] In a metal-cutting copying-machine having a tool and tracer traversed over the surface of the work and pattern, hydraulically controlled means are provided actuated by the tracer to cause movement of the cutter to or from the work, and further means actuated by phase movement of the tool relatively to the tracer are provided to maintain the tool and tracer in fixed relationship in the direction to or from the work and pattern. As applied to a milling or boring machine, the pattern 6 and work 7, Fig. 1, are mounted on a common support 5 capable of being traversed along a carriage 3 which is movable to and from a fixed column 2 carrying the tracer 21 and cutter 15. The saddle 14 carrying the tracer and cutter spindles is movable vertically on the column 2 by a screw 12, this screw and the mechanism for traversing the support 5 and carriage 3 being controlled by hand levers 8, 11, &c. The cutter spindle 16 is driven through a splined shaft 17 from a motor 18. The tracer casing 27 is secured to a slide 20 adjustable relatively to the saddle 14 to vary the distance between tracer and cutter according to the size of pattern and work by means of a screw jack 22 locked by a nut 24. The tracer tip 21, Fig. 7, is mounted on a shank 60 slidable in a tube 61 and is pressed towards the pattern by a spring 89, the tube 61 being universally mounted by means of a ball joint 62 in a tube 26 slidable within an extension 46 of the casing 27. A rod 66 is attached at one end to the shank 60 and at the other to a piston valve 70 slidable within a piston 41 which is slidable within the casing 27 and is attached to a tube 40 passing through a gland 44 in the casing 27. A piston 47 sliding in a cylinder 28 attached to the casing 27 is secured to the tube 40 which passes through a gland 43 in the cylinder and receives a head 39 on the projecting end. Oil is supplied by a pump 32, Fig. 1, from a tank 29 by means of pipes 31, 38 to the head 39 and thence to a space between the iriterior of the tube 40 and the exterior of a tube 42 secured to the piston 41 and sliding with the tube 40. The pump supplies more oil than the maximum required and the surplus is returned to the tank through a weighted relief valve 35 and pipe 30, thus ensuring a constant supply pressure. Oil is returned to the tank from the interior of the tube 42 by a pipe 31 connected to the head 39, and the pipes 31, 38 have flexible connections to allow for sliding movement of the head. During traverse of the work and pattern past the cutter and tracer, if the tracer meets a protuberance on the pattern it is depressed against the pressure of the spring 89 and slides the rod 66 rearwardly, thus moving the valve 70 to the right from the neutral position shown in Fig. 7 and allowing oil which has flowed into a central annular recess 79 in the valve by way of passages 85, 86 in the piston from the tube 40, to pass into an annular recess 72 in the piston and thence by a passage 88 to the left end of the piston. This moves the piston to the right, also moving the piston 47 to the right and displacing oil from the right-hand end of the cylinder 28, by a pipe 48, to the left-hand end of a cylinder 49 whose piston 50 is secured on a rod 51 attached to bracket 54 connected to a sleeve 56 engaging the cutter spindle 16 through thrust bearings 58. Oil also flows from the right-hand end of cylinder 49, by pipe 52, to the left-hand end of cylinder 28, these two cylinders forming a closed circuit so that movements of the piston 47 will be followed exactly by movements of the piston 50 and hence of the cutter spindle 16. This movement of the piston 41 to the right restores the neutral position of the valve 70 therein and cuts off the supply of oil to the passage 88, thus preventing further axial movement of the cutter spindle unless the tracer tip is further depressed by the pattern. If the tracer meets a cavity in the pattern, the tip 21 is pressed to the left in Fig. 7 by the spring 89 and draws the valve 70 to the left within the piston 41, thereby admitting oil by a passage 87 in the piston 41 to the right of the piston and moving the piston 50 and cutter spindle to the left through an equal distance. The saddle 14 may be traversed vertically and the support 5 given a step-bystep feed after each traverse, or the support 5 may be traversed horizontally and the saddle 14 given a vertical step-by-step feed. Reversing hand of reproduction. The machine shown in Fig. 1 produces a workpiece 7 identical with the pattern 6, and in order to enable the work to be identical with or a reverse of the pattern, the tracer cylinder 28a, Fig. 3, and cutter cylinder 49a are connected by pipes 91, 96, 92, 93, a cross pipe 97 and hand-controlled valves 94, 95, 98, 99, so that by closing either the valves 94 and 99 or 95 and 98, the top and bottom of the cylinder 28a may be connected with the top or bottom of the cylinder 49a. Compensating for loss of fluid. In order to maintain the closed circuit of the cylinders 28, 49 full of oil, an arm 127 is attached to the head 39 and carries a slotted end 128 engaging a pin 129 on the rod 107 of a piston valve 104, Figs. 5 and 13, whose casing 101 is mounted in the bracket 54 moving with the cutter spindle. If any relative movement should occur between the head 39 and the cutter spindle, the valve 104 will be displaced from the neutral position shown in Fig. 13 and oil will be allowed to flow from the pressure line 38 by a pipe 38a to one of the annular chambers 102, 103 in the casing 101, and thence by one of the pipes 124, 125 to the pipe 48 or 52, thus supplying additional oil to one end or the other of the circuit. The valve 104 is maintained in the neutral position by means of opposing springs 115, 116 engaging washers 113 loose on the rod 107 which lie against a flange 112 in a sleeve 110 attached to the casing 101. A split disc 111 of the same thickness as the flange, engages a recess in the rod and receives the pressure of the springs. A pipe 126, Figs. 5 and 13, leads from the casing 101 to the exhaust line 31 and has a connection 126a passing through a handcontrolled valve 122 to the pipes 48, 52 for filling the cylinders 28, 49 with oil or for relieving pressure in the circuit when the slide 20 is being adjusted relatively to the saddle 14. The tracer may be removed from the pattern at any time by opening a valve 381, Fig. 5, in a pipe 38b leading from the pressure supply 38a to a piston 132 attached to an extension from the rod 66 secured to the piston valve 70, thereby drawing the valve and tracer to the right in Fig. 5. The piston 132 is not packed so that the oil therein will readily pass to the exhaust line 31 when the valve 381 is closed. When the machine is adapted to produce either a duplicate or a reverse of the pattern, as in the planing machine shown in Fig. 3, the compensating cylinder 100 is actuated by an arm 188 clamped to the valve-actuating rod 107a and secured to one or the other, according to which type of copy is being produced, of the sides of an endless band 180 passing over pulleys 181, 187 on the tracer and cutter slides respectively and guide pulleys 183, 185. An arm 192 on the tracer head 39a is attached to the band 180 and causes the band to run round the pulleys as the tracer moves to and from the pattern and so long as the cutter slide 134 and valve casing 100 follow these movements exactly, no motion of the valve in the casing takes place, but if any oil escapes from the closed circuit of the cylinders 28a, 49a, the motion of the slide 134 will not be the same as that of the tracer head 39a and band 180 and consequently the valve rod 107a will move relatively to the casing 100 to admit oil to one side or other of the circuit to restore the relative positions of the cutter and tracer. The tracer casing 27 is secured to a slide 151 and the cutter 135 is carried by the slide 134, the slide 151 and saddle 141 being relatively adjustable along the cross-beam 152 of the machine and clamped by a rod 153 and hand-operated screw 154. If tilting movements of the tracer are not required, the tracer shank and rod 66 are slidably mounted directly in the casing 27, as shown in Fig. 3. Varying depth of reproduction. In order to vary the relative axial positions of the tracer and cutter so that a deeply recessed pattern may be copied in a succession of shallow cuts over the whole extent of the work, or roughing and finishing cuts, the rod 107 may be moved by hand relatively to the arm 127 through a lever 133, Fig. 5, engaging a pin thereon, in order to displace the tracer axially relatively to the cutter, the arm 127 being then disconnected from the rod by releasing a hand clamp 130, Fig. 13. A pointer 137 and scale 139, Fig. 3, are provided for facilitating the adjustment. Surmounting abrupt surfaces on-the pattern. If the tracer tip 21 encounters an abruptly rising surface on the pattern it may be tilted about the ball joint 62, Fig. 7, thereby displacing laterally the rear end of the shank 61. The rod 66 is made flexible to allow this displacement to take place. A valve 165 fitting on the end of the shank 61 is thus displaced from the neutral position shown to allow oil under pressure, which has passed into the casing 26 on the outside of the tube 68 by means of the passage 85 in the piston 41, to proceed through channels 172, 173 and past the displaced edge of the valve to a passage 175 leading to a cylinder 169 at the left of a piston 170, thus moving the piston to the right. This piston is loose on the rod 66 and is normally pushed to the left by oil passing by a small channel 176, through the right-hand end of the cylinder and then by the interior of the tube 68 to exhaust. When the piston 170 moves to the right, however, it engages a shoulder on the