Patent GB-1076075-A (GB)
Title: Abrasive wheel trimming device
Inventor: PALMER RAYMOND LESLIE
IPC: B24B53/075
Filed: 1966-04-04
Abstract: 1,076,075. Trueing grinding wheels. CHURCHILL GEAR MACHINES LTD. April 4, 1966 [April 9, 1965], No. 15146/65. Heading B3D. A device for trimming a grinding wheel for grinding a toothed gear comprises a single trimming tool 26 movable, by a rack 30 and a plurality of gears 28, 31 meshing with the rack, in a path consisting of two circular arcs joined by a straight line, the rack being capable of being positioned in alternative positions on opposite sides of a plane containing the axes of the gears with which it meshes for the purpose of reversing the direction of straight line movement of the tool. The tool 26 is carried by a holder 25 mounted on a spindle 24 rotatably mounted in a carriage 19 secured to a second spindle 20 slidably mounted in a sub-frame 12 which is rockable about a pivot 16 between operative and inoperative positions by movement of a roller (18, Fig. 2) on a lever 17 movable by an hydraulic device 14 mounted, with the pivot 16, on a base 10. The spindle 24 carries the gear 28 meshing with the rack which is also engaged by the gear 31 integral with a gear 36, the latter meshing with a gear 37 engaged by a quadrant (38, Fig. 1) rotatable by a hand lever 39. The spindle 24 also carries a gear 29 engaging a gear (40, Fig. 2) on a spindle (41) keyed to a sleeve (42) rotatably mounted in the carriage 19. Two flanged collars (43, 44) are mounted on the sleeve and a torsion spring (46) is disposed around the collars with its ends wrapped around arms (43A, 44A, Fig. 1) projecting from the collars. The arms are disposed on opposite sides of a pin (47) on an extension (48) of the sleeve (42) and on opposite sides of a pin (49) on an extension (50) of the carriage 19. When both arms contact both pins, the spring is unstressed. The movements of both the carriage and rack are limited by adjustable stops 23, 32. In operation, to trim the root of an involute gear (Fig. 2), the handle 39 is placed in one of its extreme positions with one of the arms stressing the spring. During the first part of its movement, the rotation of the handle rotates gear 24 to move the tool about arc (51) until both arms contact both pins, further movement of the handle then causing the carriage to move so that the tool moves along straight line 52 until stop 23 is engaged. Completion of the movement of the handle then causes further rotation of gear 24 to move the tool along curve (53), the gear moving against the action of spring (46). The concave involute surfaces (54) may be trimmed by conventional pantograph mechanism. To trim the grinding wheel to the profile of a tooth gap of Novikov gearing having circular arc tooth profiles, the rack 30, its guide (33, Fig. 2) and end stops (32) are removed from a cavity (34) in the sub-frame 12 and placed in a cavity (35) above the gears so that when the handle is rooked from one extreme position to the other, the tool follows an arc (56, Fig. 8), is reversed along a straight line (55), and is then moved along the arc (57). To trim the grinding wheel to the profile of a Novikov pinion, the rack is left in cavity (35) and the spindle 24 is rotated 180 degrees to position the tool inside the circle traced by its tip so that movement of the handle from one extreme position to the other moves the tool first along an arc (58, Fig. 9), then along a straight line (60) and then along the arc (59,) the surface (61) being trimmed by a conventional radial trimming device. In an alternative embodiment, the quadrant (38, Fig. 1) is moved by hydraulic means.