Patent GB-184510-A (GB)
Title: Improvements in metal working machines
IPC: B24B47/04
Filed: 1921-02-16
Abstract: 184,510. Hanson, B. M. W. Feb. 16, 1921. Screw threads, grinding; disc wheel and roller apparatus; gauges.-A machine for shaping, contouring, grinding or otherwise finishing curved surfaces comprises a fixed bed carrying the tool while the work is mounted on a longitudinally movable carriage supported on a frame which is rocked on knife edges to bring the work into operative relation with the tool, gauging devices being provided to ensure exact relative positioning of the tool and work. In an embodiment particularly suited to the accurate finishing of screw-threads the fixed bed a, Figs. 1 and 4, is provided with knifeedges 5 supporting the rocking frame b which has a rearwardly extending arm C carrying a gear-box d. Longitudinal guides on the rocking frame carry a work slide g traversed by a lead-screw h and having an adjustable supplemental carriage i provided with head and tail stocks k, l between which the work piece is mounted. The grinding wheel t driven from the main shaft 97 by a belt 99 is mounted in a box n on a slide m and may be adjusted transversely by hand wheels o, o<1>. In order to adjust the grinding wheel according to the lead of the thread to be finished the box n is mounted on a way whose centre of curvature is at the centre of the wheel. The main shaft is further connected by a belt 101 to a shaft 100 which drives a pulley 51 on a shaft mounted in the gear box d. The end of the arm C is formed with a housing for a nut 12 sliding in a worm wheel 13 operated from a feed shaft U which is turned either automatically or by hand to lower the arm C and apply the cutting feed. To relieve the work from the tool on the backward traverse the arm C is lifted at the end of the stroke by means of a cam 25 co-operating with a pivoted lever 20. For work of irregular contour such as the backing off of taps &c. a pattern disc 27 may engage the lever 20 to rock the arm C and shape the work according to the pattern. The automatic feed mechanism for the shaft U comprises a ratchet wheel 34 actuated by a pawl 36 which is connected through a system of levers shown in Fig. 1 to a rod 42 carrying collars 43, 44 coacting with a dog 45 on the work carrier. The motions of the pattern disc, releasing cam, lead-screw, and headstock spindle are all controlled from the gear box d. The shaft 26 carrying the cam 25 is intermittently driven through the ratchet clutch device shown in Fig. 8. The ratchet wheel 55 co-operates with a pawl 56 mounted on a flange 58 and an escapement device ccntrolled by the movement of the work carriage is employed to engage the pawl 56 with the ratchet wheel so as to rotate the cam 25 half a revolution to remove and restore the cut at opposite ends of the traverse. The mechanism for reversing the lead-screw h is carried by the shaft 28 having oppositely rotating gears 70, 71 which may be alternately clutched to the shaft by a member 77 and whose motion is transmitted to the lead-screw and to the headstock spindle 81 through a train embodying the usual change gears. The clutch member is actuated simultaneously with the releasing cam 25 bv means of a cam sleeve 54 on the shaft 26 and a lever 91. The latter is connected to a second lever 92 which may be manually operated to move the clutch to a neutral position to stop the machine. To stop the work automatically at the end of one of its strokes a lever 94 may be operated to move a projection 95 into the path of the pawl 56 thus stopping the cam sleeve 54 when the clutch is in neutral. In order to secure exact longitudinal positioning of the work with respect to the tool a gauge having an adjustable point 120 shaped to fit the thread is carried on an arm 121 pivoted at 122 to a bracket 115. The pivot may be longitudinally adjusted by a screwed plunger and when not in use the gauge may be swung back to the position shown in dotted lines in Fig. 11. In operation, the gauge is set relatively to the grinding-wheel by first grinding a test piece similar to the work to be finished. A trueing device for the grinding-wheel is also provided and comprises a carriage 138 pivoted on a vertical pin 137 and carrying an adjustable diamond pointed tool 142 rotatable by worm gearing about a horizontal shaft 140. The carriage 138 may be indexed about its pivot to position' the tool to true the grinding-wheel to the correct thread angle. A gauge plug 166 carried in a pivoted arm 165 is employed for setting the diamond point.