Patent GB-473720-A (GB)
Title: Improvements in or relating to pattern-controlled machines for effecting milling, diesinking and the like operation
IPC: B23Q35/18
Filed: 1936-08-11
Abstract: 473,720. Milling machines; fluid - pressure servomotors; hydraulic machines. CINCINNATI MILLING MACHINE CO. Aug. 11, 1936, No. 22150. Convention date, Aug. 16, 1935. [Class 83 (iii)] [Also in Group XXIX] A patterned - controlled machine for milling, diesinking, &c. has tool and work supports relatively movable in a plane by hydraulic cylinders and a tracer-controlled rotary fluid motor for actuating a control member which operates the control levers of two variable delivery pumps supplying the hydraulic cylinders, whereby said cylinders are operated to vary the speed and direction of the resultant movement between the tool and work in accordance with the pattern. The machine comprises a base 10 Fig. 1 having guides for a horizontally movable work table 11 and a tool-carrying ram 12 movable transversely to each other. The head 13 carrying the cutter spindle 14 and tracer spindle 223 is vertically movable on the ram 12. Spindle driving-mechanism; clutch-operating mechanism.-The spindle 14, Fig. 4, is mounted in an axially movable quill 16 and is rotated from an electric motor 24 in the ram 12 through gearing giving sixteen speeds. The motor is pivoted at 26 and adjusted by a strut 27 to vary the tension of a belt drive 31 to a shaft 32 carrying two splined gear pairs 35, 41 which are engageable with gear pairs 37, 43 on a lay shaft 19. The four speeds of the shaft 19 are doubled by a splined gear pair 46 on a shaft 44 carrying a gear 48 driving a shaft 50. Bevel gears 74 connect shaft 50 with a vertical splined shaft 76 which may be coupled direct to the spindle 14 by means of an idle gear 80. The gear 80 is mounted on a bracket 82 which may be moved axially to break the drive and simultaneously engage a clutch 85 on a pulley 79 with the shaft 76, this pulley being connected by belts 86 giving a step-up ratio with the spindle 14. The bracket 82 is movable by means of a handle 97, Fig. 1, and rack-andpinion gearing and is guided on vertical rods. The gear pairs 35, 41, 46 are movable by cam grooves 58-60, Fig. 6, on shafts 51, 54 connected by two-to-one ratio gearing 62 and driven simultaneously by a hand lever 67 and spiral gears 65. A bevel gear 68 rotates a dial to indicate the spindle speeds and the cam grooves are arranged to successively position the gears to effect a geometrical progression of speeds. Spindle feeds.-The quill 16 is adjusted axially by rack teeth thereon engaged by a pinion rotated through worm gearing from a handle 20, Fig. 1. Copying.-The ram 12, Fig. 4, is fed by a hydraulic cylinder 104 connected thereto and co-operating with a fixed piston 105 whilst the work table 11, Fig. 1, is fed by the piston rod 113 of a fixed hydraulic cylinder 111. The cylinders 104, 111 are supplied with fluid by reversible variable delivery pumps 110, 116, Fig. 28, respectively, both pumps being coaxial and driven by an electric motor 119 on the ram 12. The output of the pumps is controlled by levers 120, 124, Fig. 10, pivoting about pins 117, 118, and carrying rollers 121, 125 engaging rods 122, 126 which impinge against a roller 131 on a pin 132, Fig. 28, which is displaceable under control of the tracer in order to vary, stop or reverse the output of the pumps and hence the movement of the slide 11 and ram 12. The rollers 121, 125 are carried by levers 129 adjusted on the levers 120, 124 by screws 130, in order to adjust the output of the pumps to zero for a neutral position of the pin 132 and are held against the rods 122, 126 by springs 123. The pin 132 is mounted on a fluid plunger 133, Figs. 8 and 28, carried by a sleeve 177 which may be rotated about the axis of the tracer spindle 223 in order to vary the direction in which the pin moves from its central position and thus to determine the relative outputs of the two pumps. In this way the relative motion between the cutter and work takes place along a line parallel to the plunger 133 at any instant, and the speed of the feed motions is determined by the displacement of the pin 132 from its central neutral position. Rotation of the sleeve 177 may be effected directly by a hand wheel 226 secured thereto or through gearing 179, 180 from a hydraulic motor 181 whose rotation is controlled bv the tracer 223. The hydraulic circuits shown in Fig. 28 are controlled by a valve 184 shown in five sections 185 ... 189 in this Figure, the valve being set by a hand lever in one of three positions which enable the machine to perform the following operations, viz. : (a) contouring, i.e. following automatically under tracer control round the edge of an internal or external horizontal pattern without axial movement of the tracer except by hand control, or following round the edge of a pattern and being given a continuous spiral feed in an upward or downward direction, (b) semi-automatic profiling in which the tracer moves relatively to the pattern in a horizontal or vertical plane determined by the hand setting of the wheel 226, which setting may be varied at any time, and the tracer controls movement transverse to the plane only, and (c) full automatic profiling in which the tracer performs a series of parallel horizontal traverses relatively to the pattern, with step by step horizontal feed at the end of each traverse, and the tracer controls up and down movement also. Fluid for operating the plunger 133 is supplied by a variable delivery pump 134, Fig. 28, supplied from a sump 136 and delivering by a pipe 137 to the plunger cylinder 139, and thence passing to the exhaust line 142 past the tapered end of the plunger. The opposite end of the plunger is supplied with pressure through a pipe 145 by a variable delivery pump 143 which is coaxial with pump 134 and is driven by the same motor. A differential valve 147, also connected to pumps 134, 143 by pipes 148, 149 determines the pressure at the left of the plunger 133 by passing fluid to exhaust through a resistance 158, and also acts to accelerate movement of the plunger and to stabilize it in any set position. The output of pump 134 may be varied by operating a hand lever 167, Fig. 1, co-operating with a scale, whereby the pressure in pipe 137 may be varied to adjust the radial position of pin 132 and hence the speeds of operation of the table 11 and ram 12. Fluid passing through the differential valve 147 is also used to supercharge the pumps 110, 116, by means of a pipe 161 and check valves 166. The fluid motor 181 for determining the direction of resultant motion between the tracer and pattern is supplied from a variable delivery pump 211 by pipe 210, and a plunger 213, opposed by a spring, acts on the control lever 215 of the pump to maintain a constant output pressure and to stop delivery when sufficient pressure exists in the delivery pipe. For control (a), pump 134 must be actuated by hand lever 167 to cause a displacement of pin 132 from its position concentric with the tracer 223. The table 11 and ram 12 will then be moved to traverse the tracer towards the pattern along a line determined by the setting of hand wheel 226, an arrow being provided on one of the spokes of the wheel to indicate this direction. In the neutral position of the tracer valve 218, the tracer is slightly deflected and the valve shuts off fluid from pipes 210, 208 to the motor 181, but when the tracer is rocked from this position by contact with the pattern, the valve is moved either up or down by a ball connection 220, Fig. 8, and fluid is admitted to one of the pipes 201, 202 and thence through the control valve 184 to one side or the other of the motor, thereby rotating the sleeve 177 and altering the direction of relative feed until the tracer is moving tangentially to the pattern. The weight of the tracer valve, together with the pressure of a spring if necessary, tends to return the valve to the neutral position so that the tracer is caused to follow round the internal or external pattern. The cutter and tracer may be adjusted vertically at any time by means of a piston rod 229, Fig. 28, working in a cylinder 227 on the ram 12 and connected to the slide 13. Fluid passes from the pump 211 by pipe 216 and section 189 of valve 184 to a pipe 249 and thence to a servo-valve 247. A nut segment 255 on the valve casing is maintained by a spring in contact with a screw 260, Fig. 13, journalled in the slide 13. This screw may be rotated by a handle 269 and bevel gearing 266 to displace the casing relatively to the valve and thereby admit fluid through one of the pipes 243, 244, Fig. 28, section 187 of valve 184 and pipes 235, 236 to one end or other of the cylinder 227, thereby raising or lowering the slide 13. Movement of the slide restores the setting of the valve 247 so as to produce a servo action. In order to indicate the vertical adjustment of the slide 13, the handle 269 carries a scale 270 for indicating fractions of a revolution of the screw 260, and a linear scale 271 is attached by a pin 274 to a bracket 275 on the ram 12 and co-operates with a marker 282 adjustably secured to the slide 13 for indicating larger movements. The limits of movement may be indicated by stops 283, 284 adjustably secured to the scale 271 for co-operation with the marker 282. In order to prevent damage when the operator feeds the tracer down against the pattern &c., a relief valve 286, Fig. 28, is provided which, in the undeflected position of the tracer, is pressed by a spring 291 to the left. When the tracer engages the pattern or other object, however, the valve 218 is raised, pipe 301 is connected to pipe 297, and fluid flows therefrom by pipe 296 to the left-hand end of valve 286, thereby moving the latter to the right and connecting pipe 236, 288 to the exhaust line 293. The pressure at the top of cylinder 227 is thus relieved and downward feed of the tracer is stopped. Should the handle 269 be rotated further, the spring connection of the nut segment 255 will yield and the screw 260 will rotate without causing further displacement