Patent GB-364086-A (GB)
Title: Improvements in automatic lathes
IPC: B23B7/02
Filed: 1930-06-24
Abstract: 364,086. Lathes. SOC. D'ETUDES DES PROC•D•S MATHIEU, 20, Rue St. Georges, Paris.-(Assignees of Mathieu, J. ; 12, Avenue de Chennevieres, La Varenne, St-Hilaire, France.) Jan. 24, 1930, No. 19274. Convention date, Sept. 28, 1929. [Class 83 (iii).] In a lathe for boring and cutting off nuts b or washers from bar stock d the stock bar is clamped in a head i which is rotatably mounted in a feed carriage f which is intermittently fed by a screw 31 which engages a wheel mounted in the carriage, the wheel being fixed and serving as a nut during the feed but being rotatable to return the carriage along the screw to take up a fresh length of stock. The bar is carried in a tube c secured by a sleeve d and screw e to the head i and is clamped to the carriage by means of a sleeve and screws k. The forward end of the stock bar passes through a hollow spindle l and is fitted into a driving bush l<2> mounted in the spindle. A double thrust bearing l<1> resists the axial pressure of the drilling operation. The spindle is driven from a variable speed electric motor M through spur gearing n, and a gear u on the spindle drives through a gear v, shaft x, and gearing y, z, 1 a spindle 2 which carries a drill t mounted on a head 3 slidable along the bed g. An extension of the shaft x is connected through a clutch 5, pulley 8, belt gearing 9, and reducing epicyclic gearing 12, 13, 14 to a shaft 11 which carries cams 15, 17 for the positive feed and withdrawal of the drill head. While the drill is in operation, Fig. 9, a tool 19 chamfers the forward face of the nut while a tool 18 chamfers the rear face and partly severs the blank. The drill is then withdrawn and a tool 20 is thereupon fed to trim up the rear face of the blank and complete the parting operation, the nut then falling into a tray 21. The tools 18, 19, 20 are mounted in an oscillatory carriage 22, Fig. 6, which is moved in one direction by a cam 23 to feed forward the tools 18, 19, and is returned by a spring 25 to feed the tool 20. After severing a blank, the stock bar is advanced by means of a cam 26 on the shaft 11, which oscillates a pivoted sector having teeth 27 engaging a loose pinion 30 on the feed screw 31. The pinion 30 is integral with a ratchet wheel 32. During the return movement of the sector, which is effected a by spring 29, the ratchet wheel 32 drives through a pawl 34, a second ratchet wheel 33 keyed to the 'feed screw, thus imparting the feed movement to the carriage f and the stock bar. Reverse movement of the ratchet wheel 33 is prevented by a pawl 35. When the carriage f reaches the end of its travel, the sleeve j is undamped, a nut 36 is slacked off, and a locking plunger 39 withdrawn from a wheel 38 engaging the feed screw, the wheel being then rotated by means of a member 37 to return the carriage to its starting position. An abutment 41 limits the return movement of the sector 27. A bar 42, pivoted at 28, is connected to a rheostat 43 and is operated by a cam 44 so as to increase the speed of the motor as the parting tool is fed into the work to maintain a constant linear cutting speed.