Patent GB-478288-A (GB)
Title: Improvements in or relating to finishing and testing gears
IPC: B23Q5/56
Filed: 1936-11-26
Abstract: 478,288. Finishing and testing gears. TENNANT, W. J. (Gleason Works) Nov. 26 1936, No. 32428. [Class 60] A method of finishing bevel or hypoid gears comprises meshing a gear with its mate or with a tool gear with the axes of the gears angularly disposed to one another and rotating the gears in mesh while producing a relative movement between the gears longitudinally of the teeth of one of the gears and simultaneously producing between the gears a controlled movement in the direction of the tooth depth to maintain a uniform amount of backlash between the gears. In a machine for carrying out the invention one of the gears a pinion P, Fig. 1, driven by a motor 40 through a belt 43, shaft 36 and chucking mechanism 38 is mounted on a head 31 of the machine. The other gear G is mounted by means of chucking mechanism 58 on a shaft 48. The head and column are adjustable at right-angles to bring the gears into meshing engagement. The shaft 48 is journalled in a sleeve or quill 51 which is slidably keyed in a carrier 52, Fig. 3, so that the axis of the shaft is eccentric to that of the carrier. Mounted on the column is a motor 60 which drives a shaft 62, worm 63, Fig. 8, and a worm wheel 64 keyed to a shaft 65 to which are splined spur change gears 68 and 69, meshing with spur gears 74 and 75, Fig. 7, splined respectively to shafts 76 and 77 which shafts also carry respectively gears 84 and 85 adapted to be meshed selectively with a gear 87 integral with a sleeve 88 mounted on a shaft 90, Fig. 8. A worm 96 on the shaft 90 drives a worm wheel 97 from which project two pins 100 and 102 adapted to engage respectively the long arm 103 and the short arm 104 of a yoke member 105 pivoted at 106. During the rotation of the worm wheel the pins rock the yoke, which through rollers 107 engaging in a recess 108 in the sleeve, moves the sleeve along the shaft 90 to engage the gear 87 alternately with the gears 84 and 85 to give different speeds to the shaft 90. A quick action of the yoke is ensured by means of a load and fire mechanism comprising a spring pressed plunger 118 engaging a stud 117 secured to the yoke and a continuous drive to the worm wheel is ensured by a snap action mechanism comprising conical recesses 120 and 121 in the sleeve 88 and a diametrical bore 122 in the shaft 90. In the bore is a pin 123 with spring pressed V-shaped ends which keep the sleeve in such position that the gear 87 is in mesh with one of the gears 84, 85. The worm wheel 97 is keyed to a sleeve 98 in.which is mounted a slidable shaft 99. Keved to the shaft 99 is a disc 131 carrying a cam 132. By moving the shaft axially by means of a lever 153 either the disc or the cam may be brought into engagement with a roller 135 carried by a cylindrical bar 138 having at its lower end a roller 143 engaging a stud 144 in the arm 145 of a yoke member 146, Fig. 3, secured to the carrier 52. When the cam 132 is engaged with the roller 135 an oscillating motion is transmitted through the bar 138 to the carrier which is oscillated about ts axis thereby imparting an eccentric motion to the shaft 48 and gear G. Another cam 158 on the shaft 99 acts through a roller 160, bar 162, a follower 164 and a pivoted arm 165, Fig. 3, to give an oscillating motion to a screw shaft 175. The screw has a threaded portion engaging in a nut 178 secured in a ring 179 which is clamped between the quill 51 and a member 180 so that an axial reciprocating movement is imparted to the quill and to the spindle 48 and gear G. Springs 195 take up the backlash in the screw 178. The shaft 99 also carries cams 200 and 201 which operate respectively a double throw switch controlling the direction of rotation of the gears P and G and a single throw switch for stopping the machine after a complete rotation of the shaft 99. The double throw switch, Figs. 7 and 17, comprises a body member 205 pivoted on a pin 204, blade arms 206 and 207 are pivoted at 208 to the member 205 and carry respectively bars 216, 218 adapted to connect contacts 210, 211 and 212, 213. A plunger 214 is slidably mounted in the member 205, a spring 215 being interposed between the plunger and the arm 204. A spring 219 is interposed between the member 205 and the arm 207. A spring pressed plunger 222 urges the switch to a position in which the bar 206 connects the contacts 210 and 211. The nose of the cam 200 is adapted to move inwardly a spring pressed plunger 230, a projection 236 on the plunger being thereby brought behind the tip of the plunger 214 so that as the cam nose rides off the end of the plunger, the plunger moves outwardly and rotates the member 205 to disengage the arm 206 from its contacts and to engage the arm 207 with the contacts 212, 213. This reverses the direction of the driving motor 40. As the cam continues to rotate, its nose rides off the shoulder 240 of the plunger thereby allowing the plunger to continue its outward movement so that the projection 236 rides clear of the plunger 214 and the plunger 222 then rocks the switch back to the initial position. The single throw switch, is similar except that the arm 207 and its contacts are omitted and a dash pot device is associated with the restoring plunger 222 to ensure that after breaking contact the switch will not be rocked back to close the contact again until such an interval has elapsed as to ensure the stopping of the motors through their relays. During lapping or burnishing the gears are enclosed by a housing 280 having a door 282 on which is a switch connected so that the machine cannot operate unless the door is closed. Lapping compound is pumped from a sump through pipe 287, Fig. 13, to an elbow 290 having openings through which the compound drips into a funnel 293 secured to the door and provided with a flexible hose 295. The outlet of the hose is disposed above the gears and is held in a bracket 297 that is vertically and horizontally adjustable on a bracket 298 which is horizontally adjustable on a supporting-plate 299 slidably gripped between ribs 300 on the door 282. A brake is provided to prevent backlash and to exert a pressure between the gears. This comprises a gear pump 340, Fig. 10, driven by a belt 343 from the shaft 48 and at opposite sides connected by flexible hoses such as 344 to a sump 330. The hose which for the particular direction of rotation of the shaft is acting as the pump inlet takes up liquid past a non- return valve while the outlet hose 344 is connected by way of ducts 347 to a relief valve 35. By adjusting the valve by means of a hand wheel 356, the desired load may be put on the shaft 48. In order to allow the correct meshing relation to be obtained the head 31 carrying the pinion P is adjustable by means of a shaft 370, Fig. 12, which may be moved axially by a piston 375, the piston rod and shaft being coupled by a yoke 378 or which may be rotated by a hand wheel 374. The shaft has a threaded portion engaging within a nut 371 secured to the head 31. The yoke 378 carries a plate 385 having a hook 386 adapted to engage a magnifying bell-crank lever 387 which in turn actuates a gauge 390. The piston is first moved to its limiting outermost position and the movement of the head 31 is continued by means of the hand wheel until the gears reach the bottoming position. The pinion is then backed the required distance by the hand wheel. Subsequently for similar gears the correct relationship is obtained merely by moving the piston to its limiting position. In operation, when lapping or burnishing the operator presses a starting button and this energ zes relays to start the motors 40 and 60 to rotate the pinion P and impart a combined axial and eccentric movement to the gear G. When the cam 200 operates the switch 205 the motor 40 is reversed and continues to drive the pinion in the reverse direction until, after a complete revolution of the shaft 99, the cam 201 operates the other switch to stop the machine. At the moment of reversal of the motor 40 the pin 100 moves the arm 103 of the yoke 105 to shift the gear change mechanism 84, 85, 87 so that the shaft 99 is driven at a different speed. As the machine is stopped the pin 102 engages the arm 104 of the yoke to shift the gears back to the initial position ready for a fresh operation. The two halves of the cam 132 are differently shaped so that the carrier receives a different motion when the gears are rotating in the reverse direction. This ensures correct lapping of both sides of the teeth. For testing gears, the door 282 may be open and the lever 153 is moved so that the disc 131 is in contact with the roller 135. The movement of the lever actuates a switch 196 and the circuit arrangement is then such that the motor 60 is inoperative and the motor 40 may be run in either direction by the continued manual depression of one or other of two starting-buttons. The test is made by means of a hand brake operating on a brake drum 184 carried by the shaft 48. In a modified form of machine for burnishing or testing but not for lapping, the means for reciprocating the quill are omitted and for burnishing, springs are employed to keep the gears in bottoming position. Specification 316,578, [Class 60], is referred to.