Patent GB-807886-A (GB)
Title: Improvements in or relating to boring and turning mills and other machine tools
IPC: B23B3/10
Filed: 1956-01-17
Abstract: 807,886. Boring and turning-mills. GIDDINGS & LEWIS MACHINE TOOL CO. Jan. 17, 1956 [Aug. 1, 1955], No. 1555/56. Class 83 (3). [Also in Groups XXIV and XXXIV] A boring and turning-mill, or other machinetool, has a first rotatable element (worktable), and a second element (tool-holder), fed radially of the first element, a speed change transmission including a number of two-ratio gear sets connected in tandem, and means responsive to the position of the second element to adjust the speed of the first element in steps inversely according to radial distances of the second element from the axis of the first element. A boring and turning-mill having a heavy worktable 32, Figs. 1 and 2, is driven from a constantspeed electric motor 36, and is provided with various tool-heads, but the turret-head 42 only is described herein, this head being mounted on a vertical ram 43 and slidable radially of the work on a beam 40 which is also capable of axialadjustment on ways 41. The drive for radial feed of the tool-head 42 may be derived from the main gearing, to be described, and is controlled by a device 49 which varies the feed and indicates the position of the slide. A feed-selector 50, see below, is arranged at the same control station 48, and a hand feed-wheel 51 is also provided. Worktable drive.-The motor 36 drives, through V-belts 80, Fig. 2, a pulley 81 at the end of a series of five planetary gear trains, Fig. 7. The first four trains 90-93 are controlled by electromagnetic brakes and clutches, but the fifth train 94 is hand controlled by a lever 70, Fig. 1, adjacent the worktable. The drive up to the final train 94 is through hollow sleevemembers, but the final drive is through a shaft 84, a bevel-gear 85 and a ring-gear 86 on the underside of the table 32. This gearing gives a total of thirty-two speed changes. Main brake.-A shaft 102 passes through the hollow driving-sleeves and is splined at the final drive end to the inside of sun-wheel 146. The other end of this shaft carries a disc 195 which co-operates with stationary electromagnetic brake-elements 201. Braking may thus be effected directly on the last of the geartrains without passing through the other planetary gearing. Flywheel.-The planetary gear set 92, Fig. 7, is constructed so as to minimize the impact or jolt which would otherwise be given to the heavy worktable by changing speed under load. This gear set includes an intermediate ring member 170 with flange 170a which meshes with two sets of planetary gears 171, 172. The former engage a sun-wheel 130 of larger diameter than the sun-wheel 140 engaged by the latter set. The ring member 170 tends to rotate in the same direction as the input sun-gear 130, if the latter speeds up faster than the sun-gear 140, but in the opposite direction if the sun-gear 130 lags the sun-gear 140. The ring-gear thus stores energy which is used in a flywheel effect to overcome " shocks " due to speed-changing, the gear-set 92 always being part of the shift whenever any of the other gear-sets are changed. Control switches.-The pendant 39, Fig. 1, carries the control switch 38 for changing the speed of the worktable through the first sixteen changes. In addition, the pendant carries a jog-switch 244, Fig. 8, which operates automatically at the lowest speed, and a stop-switch 323 which stops the machine when deflected. The manual speed control switch 38 comprises a frame made up of front and rear apertured plates 210, 211, Figs. 9 and 10, held together by bolts 212. A control-shaft 214 with knob 216 extends through the frame-plates and carries a number of cam-plates C1-C4. The latter co-operate with pressure-sensitive-switches S1a -S4a through pivoted fingers 230-233. The ends of the fingers are bent over and cut away to engage the appropriate cam plates so that the required switches are permuted as the controlknob is rotated. A similar switch arrangement is provided on the control panel 48 on the beam 40 for automatic control of the table speed to give an approximate constant cutting-speed as the tool-head 42 moves radially. This switch arrangement 38A, Fig. 23, is driven by a notched ring 261a, moved in unison with the tool-slide, which moves a star-wheel 271 in steps. The star-wheel is connected by toothed gearing to the shaft 289 of the automatic switch. The gearing includes planetary wheels 295, 296, which enable the starting speed in the range to be set by a hand knob 282.