Patent GB-634682-A (GB)
Title: Improvements in or relating to machine tools
IPC: B23B39/02
Filed: 1947-08-01
Abstract: 634,682. Boring, drilling, and milling-machines. GIDDINGS & LEWIS MACHINE TOOL CO. Aug. 1, 1947, No. 20967. Convention date, July 14, 1943. [Class 83 (iii)] [Also in Groups XXIV and XXXVII] A machine tool, such as a horizontal boring, drilling, and milling-machine, comprises an elongated horizontal bed 20, Fig. 1, a work support 37 reciprocable on the bed, an upright column 22 at one end of the bed, a headstock 23 and cross-rail 30 slidably mounted on vertical guideways 55, 63 on adjacent faces of the column, and a headstock 31 mounted on the cross-rail 30 for movement transversely of the work support 37. General. arrangement.- The upper face of the bed 20 has longitudinal guides 35 for the support 37 which has depending brackets 38 equipped with . rollers 39 engaging rails 40 on opposite sides of the bed; the top of the support has guideways 45 for a transversely-movable work table 46. The column 22 is of hollow cross-section, and its base is adapted to house the transmission and control mechanism for the support 37, table 46, rail 30, and headstocks 23, 31. Two vertical wells provided in the column house counterweights which are connected by chains 57, 741 to the headstock 23 and rail 30, respectively, for counterbalancing the same. The headstock 23 is provided with main and auxiliary tool spindles 24, 25, which are driven and fed axially from a vertical shaft 58 extending through the column. The rail 30 is of rectangular cross-section, tapers gradually towards the outboard end where it is supported by a column 21 having a vertically-adjustable tailstock 26 for co-operating with the spindle 24 in supporting a boring bar, and has vertical bearing surfaces 70, Fig. 5, formed on its extensive end-section 71 for engaging the vertical guideways 63 on the column 22. These guideways 63 are constituted by a pair of rails 62 of dovetail cross-section, one rail 62 being engaged by a flange 72 on the end face of the rail 30 and the other rail 62 by an inclined locking plate 73, as shown in Fig. 5. For clamping the rail to the column 22, one of the rails 62 is engaged on opposite faces by a member 76, Fig. 4, mounted in a groove in the end-section 71 and a cylindrical plug 75 slidable in a recess in the flange 72. Clamping is effected by means of a shaft 78 which is in screw-threaded engagement with the plug 75 and shouldered at 80 to engage the member 76; the shaft 78 is mounted so as to have limited endwise movement and is adapted to be rotated by a tool applied to nuts 79, 80 splined on the projecting ends of the shaft. One such clamping device is provided above and below the rail. At the tailstock end, the rail 30 is supported on the column 21 by a support comprising adjustable front and rear sections 85, 86, Fig. 7, the section 85 being clamped in adjusted position to the column by T-bolts. The section 86, which fits slidably over the guideways 65 on the rail 30 and is secured thereto by locking-plates 88, has a pair of vertically-spaced lugs 89 straddling the section 85 and fitted with adjusting screws 91 for engaging buttons 93 on the section 85; after adjustment of the screws 91, the sections are rigidly clamped together. The spindle 32 of the headstock 31 is rotated and traversed by a separate motor M, Fig. 1, mounted on the headstock, and the weight of the spindle is counterbalanced by a weight slidably supported in the spindle housing 60. The headstock 31 is accurately located on the guides 65 by a dialtype micrometer gauge 66, Fig. 1, which is supported on a guide-rail 69 for longitudinal adjustment on the rail and coaction with a pin 67 on the headstock. Driving mechanism.-A reversible motor M<SP>1</SP>, Fig. 13, mounted at the base of the column 22 provides a direct drive through bevel gears 108 and a splined shaft 58 to the headstock 23 for rotating and traversing the spindles 24, 25. The drive for the other elements is taken from a main shaft 94 journalled in the base of the column 22 and driven from the motor Ml through a uni-directional gear unit 106 ; the shaft is driven at either one of a number of selected feed speeds provided by a variable-speed unit 95 or rapid traverse speed as determined by the setting of two clutches 98, 100. The headstock 23 is translated by a vertical feed screw 112 rotatably mounted in the column 22 and engaged by a nut 111 in the headstock casing, the lower end of the screw being driven through gears 113, 1131 by a shaft 114 journalled in the column base. The shaft 114 is driven from the shaft 94 through gearing 115, 115<SP>1</SP>, 116, 116<SP>1</SP>, 118 in either direction according to the setting of a clutch 117. For manual adjustment of the headstock, a hand crank-shaft 108<SP>1</SP> is connected through gearing 1061, 1071 with the gear 113. The worktable 46 is traversed by a splined shaft 120 which is disposed between the guideways 35 and is axially aligned with, and coupled to, the shaft 94. The shaft 120 drives through a reversable mechanism 122 a nut 125 which is rotatably mounted in the saddle 37 and engages a screw 126 secured to the table 46. The saddle 37, rail 30 and headstock 31 are traversed from an auxiliary drive shaft 132 rotatably supported in the column base and driven from the shaft 94 through gearing 1161, 133... 136 adapted to be set to drive in either direction by a clutch 137. Manual adjustment is possible by a hand crankshaft 136<SP>1</SP> through gearing 132<SP>1</SP>, 135<SP>1</SP>. The shaft 132 drives the saddle 37 through a feed screw 140 rotatably anchored in the bed 20 and engaging a nut 141 on the saddle, the drive connection between the shaft 132 and feed screw 140 being either direct or through a speed-reduction unit 142 as determined by the setting of a clutch 152. The drive for the rail 30 and headstock 31 is taken from the clutch 137 through gearing 156, 158 and a shaft 159 to a variable-speed unit 160. The outlet shaft 161 of this unit is adapted to drive either a vertical feed screw 169 engaging a nut 170 on the rail 30 for traversing the latter, or a splined shaft 173 for driving, in any position of the rail 30, a feed screw 174 engaging a nut 175 on the headstock in order to traverse the latter. A clutch 180 determines which, if any, of the two feed screws 169, 174 is to be driven. The mechanism for actuating the clutches 152, 180 is so interconnected as to prevent traversing of the saddle 37 when either the rail 30 or headstock 31 is in motion and vice versa. Switches are provided at the extreme limits of traverse of the rail 30, headstock 31, and saddle 37 for opening the circuit of the motor M<SP>1</SP> when the corresponding element reaches the end of its travel. The circuit also includes normally-open byepass switches which are so connected with the lever controlling the clutch 137 that, when the latter is engaged to move the rail, headstock and saddle, the limit switches at the ends from which these elements then move are put out of action. The operating lever for the clutch 180 controlling the rail 30 and headstock 31 is interconnected with byepass switches so as to make effective only the limit switches associated with whichever of these elements is operated by the clutch. A further normally-closed switch arranged in a shunt circuit around the limit switches of the saddle is adapted to be opened when the clutch 152 is moved from neutral to provide either rapid traverse or slow feed of the saddle 37 ; the limit switches are then conditioned for performing the necessary control. Additional normally-closed switches arranged in a shunt circuit around all the limit switches are adapted to be opened upon movement of the operating lever of the clutch 152 to either engaged position ; as long as this clutch is in neutral position, no driving connection is established for the rail 30, headstock 31 and saddle 37, but the motor M<SP>1</SP> is operable to drive the headstock 23. Both motors M, M<SP>1</SP> are reversible and, when their relay circuits are interrupted, are adapted to be reversed and, by the introduction into the supply circuit of a shunting resistance, brought to a standstill without shock.