Patent GB-477472-A (GB)
Title: Improvements relating to pattern controlled milling machines
IPC: B23Q35/18
Filed: 1936-08-18
Abstract: 477,472. Milling-machines. STEVENS, A. H. (Cincinnati Milling Machine Co.) Aug. 18, 1936, No. 22774. [Class 83 (iii.)] [Also in Group XXIX] A pattern-controlled milling-machine has the cutter and tracer slides, and the work and pattern slides each fed by a hydraulic cylinder, the flow to all the cylinders being proportionally controlled by manual adjustment so that the machine may reproduce to a variable enlarged or reduced scale, or may produce copies of reverse hand from the pattern, or work in intaglio from patterns in relief. The machine comprises a bed 10 carrying a vertical column 11 which slidably supports on one side the cutter slide 25 and on the other side the tracer slide 37. The work table 13 slides along horizontal guides 12 on the bed at one side of the column and the pattern table 19 along guides 18 at the other side. Spindles.-The cutter spindle 43, Fig. 9, is mounted in bearings 44 in a quill 46 provided with helical rack teeth 47 for axial adjustment by means of a worm 48 rotatable through bevel gearing from a hand wheel 52. A sleeve 57 journalled in bearings 45 is splined on the portion 55 of the spindle and is driven by gearing 58 from an electric motor 61, Fig. 1, mounted on the cutter head 28. Copying.-The cutter head 28 is vertically adjustable by a screw 30, Fig. 1, on a slide 27 which is given an axial copying movement on guides 26 on the slide 25 by means of a hydraulic cylinder 33, Fig. 11, whose piston rod 35 is attached to the slide 27. The tracer slide 39 is given an axial copying movement by means of a similar cylinder 40, the piston rods projecting through both ends of each cylinder in order to provide equal piston areas on opposite sides. The work and pattern tables 13, 19 are fed respectively by hydraulic cylinders 15, 21, whose piston rods 17, 23 are attached to the slides, and fluid is supplied to the system by a constant or variable displacement pump 80 driven by an electric motor within the bed of the machine. The tracer 20, Figs. 1 and 10, is carried by a spindle 62 having universal lateral and axial movement relatively to a flange 67 having a knife edge 66. A head 63 on the spindle has a plane surface 65 engaging the knife edge and an overhanging flange 64, and is biassed into the position shown by means of a freely rotatable spindle 70 engaging the stem 72 of the tracer valve 76, Fig. 11, and a spring 73. Fluid proceeds from the pump 80 through filters 84, 85, to a speed control valve 87 which is adjusted by a hand lever 93 to stop the supply or to divert a portion of it to exhaust through pipes 94, 99 and thus determine the speed of operation of the machine. A balancing valve 96 maintains the division of fluid between the exhaust pipe 99 and the pipe 100 which operates the machine. The pipe 100 supplies pipes 101, 102, the former leading through a resistance 103 to the tracer valve 76 and the latter through a resistance 104 to the control valve 113 for the slide cylinders. A balancing valve 112 maintains the distribution in pipes 109, 111 established by the resistances 103, 104. Valve 113 is operated by the tracer valve 76, which is adjustable axially by means of a screwed sleeve 68, Fig. 10, so as to divert all flow from pipe 109 to pipe 117 when the tracer is out of contact with the pattern. This moves the valve 113 to its extreme left-hand position and the fluid then proceeds to the exhaust line 99 past the resistance of a tapered spool 124 of the valve and passage 122. In this position of valve 113, port 126 is connected to port 128 to cause feed of the tracer and cutter towards the work and pattern, and port 129 is closed to prevent operation of the pattern and work slides. Fluid flows from port 128 to a balance valve 144, moving this valve to the right from the position shown, and thence by pipe 161 to a flow dividing valve 163 which may be set by a handle and pointer 177 connected to a screw 176 to divide the flow between pipes 170, 171, the former supplying the cutter cylinder 33 and the latter the tracer cylinder 40, whereby the ratio of movement of these two slides may be varied to cause the machine to reproduce an enlarged or reduced copy. Flow in the pipe 174 passes through a reversing valve 184, adjusted by a hand lever so as to supply one end or the other of cylinder 33 and thus cause the cutter to move towards the work together with movement of the tracer towards the pattern, for production of a copy similar in relief to the pattern, or to cause the cutter to move away from the work as the tracer approaches the pattern for production of an intaglio copy from a relief pattern. The flow of both pipes 174, 175 passes to cylinders 33, 40 through hand-operated valves 182 which may be rotated from the positions shown in order to admit fluid from the supply pipes 202 to either end of the cylinders in order to adjust either slide 27, 39 independently by hand. When the valves 182 are used in this manner, the rest of the circuit is cut off from the pipes 202. Exhaust from the cylinders 33, 40 proceeds by pipes 207, 190 to a balance valve 167 and then to a dividing valve 160 similar to valve 163 and set to the same ratio. These flows then unite in pipe 158, and if the balancing valve 149 is in the left-hand position shown, pass through a check valve 165 and pipe 150, through valve 113 to the exhaust line 99. When the tracer engages the pattern the valve 76 is moved to the right, cutting down supply to port 118 of valve 113 and admitting supply to port 120 and thus moving valve 113 to its middle position, as shown in Fig. 11, the flow through ports 118, 120 proceeding to the exhaust line 99 in equal quantities through ports 122, 135. This closes ports 127, 128 to stop further movement of the tracer and cutter slides, partially closes port 130 to cause the required back pressure in the work and pattern cylinders 15, 21 and opens port 129 to start movement of the work and pattern slides. Fluid from port 129 proceeds through balancing valves 141, 149 to pipe 155 and is then split by a dividing valve 157, similar to valve 163 and set to the same position, between pipes 217, 218 which respectively supply cylinder 21 for the pattern table 19 and the cylinder 15 for the work table 13. The setting of valve 157 thus determines the ratio of movements of the pattern and work to vary the horizontal scale of reproduction, this ratio being maintained by a balance valve 219. Fluid from pipe 217 proceeds by pipe 220 to a reversing valve 224, movable by dogs on the table at opposite ends of a traverse, and then to the cylinder 21, and fluid from pipe 218 proceeds by pipe 221 to the reversing valve 224 and then by pipe 232 to a reversing valve 235 which is set by hand to cause the work table 13 to perform the same or opposite movements as the pattern table 19, thus producing a similar or reversed copy of the pattern. Hand-controlled valves 182 are provided for hand adjustment of the slides 13, 19 from supply pipes 202. If the pattern remains parallel to the guides 12, 18, the traverse of the pattern and work tables continues, but if projections or hollows on the pattern are encountered the valve 113 is moved to the right or left by the tracer valve 76 to cut off supply to the cylinders 15, 21, and admit supply to the appropriate ends of cylinders 33, 40. Exhaust from the cylinders 15, 21 passes through reversing valves 235, 224 to pipe 240. Reversing mechanism.-The valve 224 is moved to reverse the reciprocations of the work and pattern tables by means of dogs 251, Fig. 2, on the work table 13. These engage a lever 250 on a shaft 242 connected by a load and fire device to the valve stem 241 so as to give a sudden movement of the valve. Step-by-step feeds.-At each end of a reciprocation of the work and pattern slides the cutter and tracer slides are given an upward or downward feed by means of the reversing shaft 242 which carries a pinion 253, Fig. 2, engaging a rack 254. Double toggle levers 255, 257 on the rack carry pawls 256, 258 respectively which engage a ratchet wheel 259 on a horizontal shaft 267. The pawls act in opposite directions so that a feed will be given at each end of the table traverses, or either pawl may be lifted out of engagement to give a feed at one or other end only. The toggles are connected to the rack by an adjustable lost-motion connection so that the stroke of the pawls may be varied or may be made unequal. The shaft 267 is connected directly by bevel gearing 270, Fig. 1, to a vertical screw 271 for feeding the cutter slide 25 and the screw is connected by bevel gearing 273 and change gearing to a screw 285, Fig. 2, for feeding the tracer slide 37. The change gears are adjusted to give a ratio of cutter slide and tracer slide feeds equal to the copying ratio determined by the valves 157, 160, and 163. The drive to the screw 285 also includes a clutch so that either slide may be adjusted separately by handles 268, 291, Fig. 1, or the two may be fed together automatically. The operator may thus stand adjacent the tracer 20 when adjusting it vertically by the handle 291.