Patent GB-324077-A (GB)
Title: Improvements in or relating to hydraulically-operated metal cutting and like machinetools
IPC: B23Q5/26
Filed: 1928-10-17
Abstract: 324,077. Heide, H. C., (National Automatic Tool Co.). Oct. 17, 1928. Drilling-machines.-A metal-cutting or like machine tool is provided with a head which is rotated continuously by fluid pressure means and which carries a number of rotary spindles which are fed vertically by fluid pressure during the rotation of the head. The base 1 carries a column 2 round which rotates a work-table 3 and spindlehead 4, these two members being connected together by a cylindrical member 5. The head carries individual power units 6 actuating symmetrically-arranged spindles 7 operating on workpieces secured to the table 3. The table and spindle-head are driven from a power shaft 9 through gears 11, shaft 10, gearing 12, clutch 14, change gears 16, worm gearing 19, and spur gear. ing 21 .. 23. The spindles are also rotated from the shaft 10 through bevel bearing 26, shaft 27 and spur gear trains 28 .. 34, the gears 34 being splined on the spindles to permit the spindle reciprocations. A thrust bearing 35 supports the weight of the rotary parts and bearing surfaces are also provided at 36, 36<1>. The column 2 carries a stationary gear 39 which is connected by gears 42, 43 mounted in the spindle head, with a gear 44 mounted on a shaft 45 which thus also remains stationary. Each spindle is fed by a separate hydraulic power unit comprising a cylinder 48 having a piston whose rod is provided with rack teeth engaging a gear 52 mounted on a sleeve 53 which is connected to a shaft 57 by means of an index plate 55. The shaft 57 carries a gear 58 engaging rack teeth on the spindle. An adjustable stop mounted on a fixed arm 70 co-acts with a projection 71 secured to the index disc to provide a positive stop for the spindle feed. By adjusting the index pin 62 around the disc 55, the stop mechanism may be set to arrest the spindle at any desired position while still retaining the full spindle movement produced by the engagement of the rack 51 with the gear 52. The fluid pressure system comprises a reservoir 84 and sump 86 and an electric motor 87 is arranged to drive a high-pressure low volume pump 88 (which may be of the intermeshing gear type) and a low-pressure high volume pump 89 preferably of the centrifugal type. Electric current is conveyed to the motor from a rotary plate 100 having brushes engaging a stationary plate 99 which is supplied by a lead 97. The reservoir 84 is maintained under constant air pressure by a supply pipe 93 and fluid at this pressure is continuously supplied through a pipe 112 to the back of the piston in the cylinder 48. The high pressure pump draws fluid from the reservoir 84 and delivers into a pipe 96 which has branches connected to the various units. The valves controlling the cylinders 48 consist of a main admission valve 101 and exhaust valve 102, these valves being actuated by a stationary double cam 46 engaged by rollers 106, 107 on the respective valve stems. The valve 101 also carries a projection 109 coacting with a latch 82 operated by a cam 78 on a member 76 secured to the piston rod 50. A controlling valve 117, Fig. 9, is arranged in the high-pressure pipe 118 between the admission valve and the cylinder 48, this valve consisting of a hollow rotary member 121 which has a triangular opening 122 and which may be rotated so as to uncover one or more of a series of passages 123 cut in the valve body. In operation, when the valves are in the position shown in Fig. 10, low pressure fluid from the reservoir 84 flows through the pipe 112 to the right hand end of the cylinder 48 and also, through the valve portion 104, to the left hand side of the piston. The difference in the front and back piston areas causes the piston to move to the right at high speed, thus giving the rapid approach feed of the tools to the work. At a predetermined point, latch 82 is withdrawn by its cam from the valve rod 109, so that the valve is moved by a spring to the right, the roller 106 having passed over the cam swell 131 to permit this movement. In this position the low pressure fluid is cut off from the left hand end of the cylinder while high pressure fluid is admitted at this end through the valve portion 103 and pipe 118. This position gives the slow cutting feed of the spindles. Finally the valve 102 is actuated by its cam to give the position shown in Fig. 12, wherein the left hand end of the cylinder is open to exhaust through the valve passage 105 and pipe 120. The constant pressure then moves the piston back to the left giving the high speed return movement of the spindles.