Patent GB-283476-A (GB)
Title: Improvements in and connected with machines for finishing, rectifying or profiling gear teeth
IPC: B23F23/08
Filed: 1927-09-15
Abstract: 283,476. Lees-Bradner Go., (Assignees of Schurr, C. H.). Jan. 10, 1927, [Convention date]. Gear-cutting.-In a machine for finishing, rectifying, or profiling gear teeth by axial movement between a gear-form tool in meshing engagement with the blank, the engagement being accurately determined by master gears on the tool and work spindles, the tool spindle is bodily adjustable about an axis parallel to the work spindle to bring the .tool and work and the master gears into correct mesh. The machine may be employed for carrying out the gear finishing method described in Specification 274,859, [Class 83 (iv), Metals, Working]. The blank 1 on a stem 2 is mounted in a collet 24 carried in a sleeve 25 in the work-spindle 3 which rotates in a sleeve 8 in a reciprocating quill 5. Thrust ball bearings 9 are provided to take up end thrust on the work-spindle which may be rotated within the quill by a helical gear 16 driven by a gear 75. A taper-shank master-gear 20 is mounted at the opposite end of the work-spindle from the blank, a bolt 21 screwing into the collet 24 and being rotated by its head 22 to close the collet and to draw the master-gear shank firmly into the spindle. Tool-spindles 29 are arranged around the work-spindle and are provided at opposite ends with tools 27 and master-gears 28. The tools are clamped between plates 30 by a nut 32 and the spindles are mounted in bearing-sleeves 35 in a quill 36. The tool-spindles are further supported at opposite ends by outboard bearings 43, 46 mounted in brackets secured to the quills. The tool-spindle is eccentric to the axis 53 of the quill so that by rotational movement of the quill the tools may be made to approach or recede from the work blank. As shown in Fig. 16, rotation of the quills in a direction to bring the tool axes 210 into the line joining the centres 53 will set up a toggle action to give considerable pressure between the tools and the work. In order to apply this torque to the tool quills, each quill is provided with a segment 49 engaged by rack segments 55 adjustably keyed on a threaded bar 54 which is held against rotation by means oi a head 60. The bar 54 is actuated by means of cam surfaces 62, 63 milled in the sides of the head 60 and coacting with complementary cam surfaces on a slide 64 which straddles the head 60 and is moved by means of a pivoted lever 67. The gear 75 which drives the work-spindle is driven from a gear 76 on a shaft 88 which is connected by further change gearing 97 with a shaft 103 carrying a fast pulley 104 and two loose pulleys 105, 136 the pulleys being driven from the main power shaft 109 by open and crossed belts 106, 107. The powe shaft is driven by belt 112 running on fast and loose pulleys 110, 111 respectively. Reciprocation of the work spindle is effected from the shaft 109 through worm gearing 114, shaft 115 change gears 117, worm gearing 119 and shaft 121 driving the cam 122. This cam is arranged to oscillate a shaft 132 which carries a gear 19 engaging a rack 18 on the lower side of the work quill 5. The stroke of the work support may be adjusted for blanks of different longitudinal dimensions. During the operation, the direction of rotation of the work spindle is automatically reversed. For this purpose belt shifters 137, 138 are provided in conjunction with the belts 106, 107, and are connected to rods 143, 144 operated by cams on a drum 150 driven from the main shaft 109. In order to facilitate the reversal, the belt on the fast pulley 104 is shifted somewhat in advance of the belt on the loose pulley in each case. The machine is started by shifting the main driving- belt 112 by means of a hand-lever 154. This actuates a belt-shifting bar 157, which is thereupon automatically locked until it is tripped by a cam 158 on an oscillating shaft 159. In the operative position of the bar 157, a spring 161 is compressed and locking bolts 168, 169 engage shouldered recesses 164, 165 in the bar 157. The ends of the bolts 168, 169 are provided with lugs 179, 187 coacting with the cam 158 in the manner shown in Fig. 10. In this position a shoulder 173 on the locking bolt 109 enters the notch 165 in the bar 157 but the corresponding shoulder on the other locking bolt is prevented from moving forward by the cam. During the operation of the machine a cam groove 181 on the back of the cam 122 oscillates an arm 183 to rock the cam shaft 159. At a predetermined point the cam 158 allows the bolt 168 to move forward and withdraws the bolt 169, which is locked in its withdrawn position. Finally, on the return movement of the cam, the locking bolt 168 is also withdrawn until the bar 157 is released whereupon it is retracted by its spring 161 to shift the belt and stop the machine. If it is desired to stop the machine before completion of the cycle a pedal 198 is depressed and this actuates a plunger 193 having a head 197 which engages the locking bolts 168, 169 and moves them back to release the bar 157. In operating the machine in the manner described in Specification 274,859, [Class 83 (iv), Metals, Working], the teeth of the gear-form tools are chamfered on both edges at 200, 201, Fig. 21. The tools are first rocked away from the work spindle by the lever 67 for mounting the blank, and are then restored to a position to apply the necessary operative pressure. The blank is moved axially until it passes entirely clear of the tools and is then returned so that it is worked by the opposite set of chamfers. On completion of the operation the machine is automatically stopped as described. If desired the cycle of operations may be varied so as to finish a gear and stop the machine after one or any number of passages of the tools through the work.