Patent GB-778165-A (GB)
Title: Improvements in or relating to diamond truing devices
Inventor: DEAKIN THOMAS MEYRICK
IPC: B24B53/065
Filed: 1954-06-21
Abstract: 778,165. Trueing grinding wheels. DEAKIN GEARS, Ltd. June 17, 1955 [June 21, 1954], No. 18152/54. Class 60 A diamond or like trueing device for dressing grinding wheels having complex profiles has the trueing tool 5, Fig. 2, mounted in a carrier 6 adapted to be displaced around the contour of the grinding wheel by a single drive acting through a train of articulators coupled in series and each having a pair of elements relatively displaceable in a preselected manner appropriate to a respective section of the profile to be traversed and at least all but one having associated therewith respective restraints which are graduated in increasing strength in the order in which the articulators are required to become operative during traverse of the tool over the profile; the common drive effecting the several relative motions of the articulates is applied to one element of the articulator having the strongest restraint and the reaction thereto is taken, by the articula- or having the next weaker restraint and so on (if there are more than two articulators) through the whole train to the one having the minimum restraint. The machine is described as applied to the trueing of a grinding wheel 1, Fig. 3, which comprises a plane annular working face 2, cylindrical or conical edge 3, and conical back face 4, and is intended for grinding the tooth flanks of spur or bevel gears. The carrier or head 6, Fig. 2 is supported in a bracket 12 by a rotary bearing 'assembly 9 permitting the head to pivot on the bracket about the vertical axis OP, and the bracket 12 is carried in turn from a linear slide 13 by a rotary bearing assembly 10 permitting the bracket to pivot about a horizontal shaft 36. The head 6 is keyed on a shaft 14 which is supported by the bearing 9 in the bracket 12 and at its upper end is associated with a spring carrier 20 for imposing resilient restraint upon the relative angular movement between the head and bracket. The carrier 20. which is housed between a cup 19 in the head 6 and a cup 17 supported from the bracket 12, has two opposed springs 23, 24 connected at one end to the adjacent cup and at the other end to the carrier; a stop on the carrier co-operates with abutments on the cups to define the limit of movement of the head 6. The lower end of the shaft 14 carries a gear sector 34 meshing with a pinion 35 on the shaft 36 which runs in bearings 37, 38. The bearing 37 is mounted within a part 41 which carries the inner race 43 of the bearing assembly 10, is integral with the bracket 12, and is formed with a ring gear 47 meshing with a spur gear 48 on the periphery of a cup 49 co-operating through a spring carrier 51 with an opposed cup 50 on the slide 13; the spring carrier 51 is similar to the spring carrier 20 but of weaker form. The bearing 38 is carried in a block 44 fixed to the slide 13 The shaft 36 is rotated through gearing 54. 55 with or without the interposition of a free double-sided rack, from a shaft 56 which carries a drum 58 arranged to be driven by cables from a driving head in the matchine. At the start of operation, the tool is positioned on the annular face 3 of the rotating grinding wheel, and upon the application of a forward driving torque to the drum 58, the stops on the spring carriers 20, 51 so co-operate with the abutments on the cups as to restrain the head 6 from swinging about the axis OP and. the bracket 12 from swinging about the shaft 36, the reaction to the input torque being transmitted via the sector. 34. bracket 12 and ring gear 47 to the cup 49: the restraint provided by the spring carrier 51 then resists rotation of the shaft 36 sothat the gear. 54 receives a lateral reaction thrust resulting in the slide 13 moving on its bearings 11 to the limit of its movement and the tool being traversed overthe distance C, Fig. 3, across the annular face 3 of the wheel. Maintenance of the input torque then causes the reaction at the sector 34 to overcome the torqueexerted by the weaker spring carrier 51 so that the bracket 12 rotates about the axis OQ through 90 degrees and the tool traverses the arcuate path B, Fig. 3. At this stage, the stop on the spring carrier engages an abutment on the fixed cup 50 and the full input torque is applied to the shaft 14, thereby overcoming the resistance of the spring 23 so that the head 6 swings about the axis OP for the traverse of the tool over the path A, Fig. 3. If desired, trueing may start over the path A, the drive to the drum- 58 being reversed so that the operation proceeds in the opposite direction until, after trueing the face 3. the drive may be again set in forward direction to traverse the tool over the paths D, E, Fig. 3. The supports for the mechanism includes a mounting plate 45 having a conical trunnion 60 permitting adjustment of the mechanism about the axis OQ to vary the angle between the direction of travel of the slide 13 and the plane of the grinding wheel (i.e. according to the conicity of the wheel). The tool 5, Fig. 5A, comprises a tip welded or brazed to the lower end of a plunger 63 which, to permit its vertical adjustment in the head 6, carries a bridge 64 urged upwardly by a spring 68 against a hard knob 69 on a stud 65 screwthreaded in the head; a spring-pressed plunger 72 locks the knob in adjusted position. The resilient restraints described may be replaced by pneumatic servomotors or friction couplings having graduated frictional resistances to relative motion between the coupled elements, and where part of the traverse of the tool is in the vertical plane the necessary restraint may be produced by gravity. To produce a sharp edge or corner at the junction between the faces A, C instead of the arcuate edge B, the tool is set beyond the axis OQ so that it swings away from the wheel when the head 6 turns on the bearing 9 and at the start of its subsequent travel the tool meets the wheel to form the corner. The device may be used in a gear grinding machine in conjunction with a face trueing device constructed as described in Specification 778,164, the latter device would then be used to true the face 2, Fig. 3, and the present device the remainder of the profile.