Patent GB-320254-A (GB)
Title: Improvements in or relating to machines for making bolts, screws and the like
IPC: B23G1/12
Filed: 1928-11-02
Abstract: 320,254. Arnold, G. Nov. 2, 1928. Lathes.-Finished machine screws or screw blanks are produced from the bar in a non-rotating work lathe having a combined hollow-cutter head and rotary tool-head and also a reciprocating-saw nicking adjacent for the heads. The bar 17 is fed into the machine through a guide in a quasi tailstock 65 mounting an extension 66 carrying a series of vice jaws 87, Fig. 25, carried by chain links 81 running over sprockets one of which is adjustable at 77, Fig. 1, and the other is driven by a gear train terminating in a wheel 68 meshing with a worm 6 on the hub of the tool-head 4. As the rising and approaching links bring their vice jaws into position, oscillating sectors 78 press in pins 84 acting on the jaws through leaf springs 88. The pins are locked to clamp the jaws on the bar by spring-actuated cutters 85 which in turn are released by contact with rollers 79, Fig. 2, as the links are about to leave the bar. The bar is thus always gripped by several of the vices and is fed at a speed correlated to that of the rotary tool-head. The bar enters the tool-head through a fixed guide 67 having a squared portion 67' that prevents a bush 40. formed with a worm 39, from rotating with the head. A worm-wheel 22 carried by the head has a planetary motion round the fixed worm 39 and is geared both to a rotating turning-tool 9, Fig. 9, that turns down the bar after the manner of a rotary chasing-cutter, and to a cam 25, Fig. 12. The tool 9 is carried by a casing 8, Fig. 5, angularly adjustable about the axis of a worm shaft 18 forming part of the driving-train under the control of a screw 64 to adjust the depth of cut. A second fixture 30, Fig. 11, also on the head 4 carries the cam 25 which by means of a pin 46 on a stud 44 traverses a tool-holder 43 parallel to the rod but at a different rate from it in order to cut a thread of the desired pitch. A second cam 27 on a shaft splined in the first cam shaft slides with the toolholder and controls the depth of cut in chasing by contact with a head 63 mounted as shown in Fig. 5 on a lever 28 carrying the cutter 29 and pivoted at 28<1>. At the end of the threading operation the cam 25 feeds the cutter axially at the same speed as the bar while a rise on the cam 27 feeds the tool in radially to cut off the finished screw. The cutter 9 acts in the space between the bush 40 and an extension guide 41 which is slotted at 42 to pass the cutter 29. On completion of the parting-off, the cutter 9, Fig. 12, acting on a two-armed lever 35, permits a spring 33 to withdraw a pin 32 from a clutch face 31 of the driving gear for the cam 25, thus allowing the cam to be returned rapidly by the pressure of the spring 45. The cutter 9 is connected to its driving gear by a clutch which may be disengaged to permit free rotation for purposes of adjustment or for removal of a partly worked bar. The head end of the screw being partedoff is supported by a further sleeve 55 mounted in a second quasi tailstock 54 and slotted at 56<1> to pass a detector finger 60, Fig. 17, and at 56 to permit ejection of a completed screw and provide passage for a reciprocating saw 57 which also serves as an ejector. A cam 5, Fig. 1, on the hub of the tail-head 4 tends to oscillate a spring- controlled rock-shaft 48 having an arm 50, Fig. 16, working between pins 59 on the saw-holder 58. As a screw head reaches the detector 60 it cams the detector back, raising the long arm 62 of the bell-crank to engage a notch 62<1> with a pin 50<1> on the arm 50 and lock the saw in its retracted position. When the head has passed into position for nicking, the shank portion of the screw permits the detector to advance again, freeing the saw which ejects the previously nicked blank and nicks the following one.