Patent GB-938246-A (GB)
Title: Improvements in machine tools
IPC: B23G1/32
Filed: 1962-02-26
Abstract: 938,246. Thread milling machines. SUNDSTRAND INTERNATIONAL CORPORATION S.A. Feb. 26, 1962 [March 17, 1961], No. 7348/62. Class 83 (3). A thread milling machine comprises a rotatable work spindle, a tool slide movable in both parallel and transverse directions relative to the spindle axis, reciprocable cam means having a pair of cam surfaces, for moving the slide, and a common motor for reciprocating the cams and rotating the spindle. Work spindle 22, in Figs. 1, 2, is rotatably mounted in a fixed headstock, in line with a tailstock 23, and a cutter head 25 mounted on a compound slide 30, 33, carries a tool spindle 26 rotatable by a motor 27. A carrier 40, Figs. 4, 6, movable in a direction normal to spindle 22 carries a sine bar 42, pivotable about a pin 44, and a cam 43, pivotable about a shaft 53, the sine bar producing the lead of the thread to be cut and cam 43 producing the feed. Sine bar 42 is adjustable by a wedge 95, Fig. 8, movable by a shaft 98 rotatably carried in carrier 40, Fig. 4, the adjusted position being read from a dial 100 rotated from the shaft by a gear 102, and cam 43 is adjusted by a wedge 88 screwed to a shaft 86, the adjusted position being read from a dial geared to the shaft at 93. A cam follower 48 mounted on a bracket 49, Fig. 4, carried by a shaft 50 is pivoted to engage cam 43 by an hydraulic cylinder 51. Shaft 50 is rotatably mounted in base 20 and slidably carries a gear-wheel 122, Fig. 5, which meshes with a rack 125 secured to cross slide 33 so that as shaft 50 is pivoted by cam 43, when carrier 40 moves to the left in Fig. 4, slide 33 feeds the tool into the work. Backlash is prevented by a spring 126 and a feed stop 132 can be adjusted by rotation of a shaft 133. Sine bar 42 engages a shoe 46, Figs. 6, 8, pivotally mounted on a spring-urged slide 151 by a pin 150, the slide having a pin 153 which is engageable with the hardened end of a piston-rod 154, Figs. 2, 6, 9, extending from an hydraulic cylinder 155. A screwed shaft 162 connected to cylinder 155, is threadably engaged with a collar 163, Figs. 9, 10, mounted within slide 30, so that when carrier 40 is moved from right to left in Fig. 4, sine bar 42 will move shaft 162 to the right, Fig. 9, and due to the threaded engagement of the shaft with collar 163, slide 30 will move to the left, Fig. 9, thus providing the lead of the thread to be cut. The position of slide 30 may be adjusted by rotating collar 163 by a worm and wheel 168, 169, Fig. 10, the collar then being locked by a brake 170. An hydraulic cylinder 55, Fig. 4, carries a piston 56 rotatably coupled to a shaft 57 having a collar 60 which is adjustably screwed into a sleeve 60. Sleeve 60 is adjustably screwed into a bracket 61 secured to carrier 40 and the latter has a rack 65 which is connected to work spindle 22 through gears 66, 68, 69, Figs. 4, 6, clutch 71 and gears 74, 75. The clutch is normally engaged so that as carrier is moved by cylinder 55 spindle 22 will be rotated and cams 42, 43 will produce the lead and feed of the tool. Backlash in spindle 22 is prevented by a vane type hydraulic pump 80 but when clutch 71 is disengaged the connections of the pump are changed so that the pump acts as a motor to drive the spindle in order to perform a facing operation. The length of travel of carrier 40 and thus the number of revolutions of spindle 22 is adjustable by a collar screwed on to shaft 57 which engages a switch 109 to discontinue the fluid supply to cylinder 55. The depth of feed in of cutter head 25 is adjustable by varying the position of collar 60 which coacts with a switch 111.