Patent GB-1319790-A (GB)
Title: Grinding machine
IPC: B24B49/00
Filed: 1970-11-13
Abstract: 1319790 Grinding CINCINNATI MILACRON-HEALD CORP 13 Nov 1970 [25 Nov 1969] 54206/70 Heading B3D A grinding machine for finishing a surface of revolution of a workplace 16, such as the outer face of a tapered roller bearing, comprises a base 11, a workhead table 12 on the base for supporting the workpiece, a wheelhead table 13 on the base having a rotatable spindle 19 with an abrasive wheel 21, means 12 supporting one of the table 13 for sliding motion transverse of the axis of the surface of revolution, a secondary slide 43 associated with said one table 13 and mounted for transverse sliding movement independently of said one table, a first stepping motor 58 connected to the base for effecting sliding motion of the secondary slide, and a second stepping motor 28 connected on occasion between said one table 13 and the secondary slide to produce the sliding motion of the table. The table 12 carries a workhead 15 for the workpiece 16 which is loaded on to shoes 29 by a device 24 and held by rollers 34, 35 against a platen 31 driven by a motor 32. Within the platen is an air gauge 33 for taking a continuous reading of the size of the workpiece The table 12 is movable along guideways 59 by an hydraulic motor 61. The wheelhead table is movable along guideways 62 by an hydraulic cylinder 26, a retractable stop mechanism 27 operated by the stopping motor 28 being located at the front of the machine. The stop mechanism is secured to the table 13 and has a contact element 37 for engaging a hardened face 42 on the secondary slide 43, a second hardened face 46 on the slide being provided for engaging a contact element 45 on a horn 44 depending from the table 13. The contact element 37 is slidably mounted in a housing 27 and is movable by a ball screw 38 driven manually by a knob 48 or a worm drive 41 from the stepping motor 28. The secondary slide 43 is movable by a ball screw 57 driven by the stepping motor 58. In operation, the work-table is moved rapidly to the point A, Fig. 10, so that the abrasive wheel 21 is within the workpiece 16 and the cylinder 26 supplied with fluid pressure to move the wheelhead so that contact of the wheel with the work occurs at point B. The workhead table is reciprocated while the wheel is advanced for a controlled force rough grinding operation. At point C which is determined by a timer, the wheelhead is retracted to point D to relieve deflection of the spindle 19. Further retraction by cylinder 26 causes the horn 44 to engage the rearward facing surface of the secondary slide 43 which is moved rearwardly a compensating distance by pulses supplied to the stepping motor 58. The cylinder 61 is then actuated to move the workhead so that the dresser 23 dresses the wheel to a point G. Cylinder 26 moves the wheelhead to point H to reengage the wheel with the workpiece and rough grinding continues to point I where a second timer retracts the wheel to point J for a second dressing of the wheel. The wheelhead is retracted to point K, compensation being effected to point L where the table 12 is again moved for the dresser 23 to move past the grinding wheel to point M. The wheelhead is again advanced to point N for a controlled force fine grinding to point O indicated by the gauge 33 whereupon retraction is effected to point P to remove the deflection of the spindle 19, grinding continuing by "spark out" until final size is reached as indicated by the gauge and the wheelhead retracted to point O. The movements of the secondary slide and stop 27 by the stepping motors 28, 58 is effected by definite numbers of pulses supplied to the motors by an electrical circuit. The slide 43 and motor 58 are also controlled for setting the machine when a new wheel is fitted. The tables are mounted for movement on hydrostatic films.