Patent GB-1504275-A (GB)
Title: Cylindrical grinder
IPC: B24B41/06
Filed: 1976-12-01
Abstract: 1504275 Grinding LITTON INDUSTRIAL PRODUCTS Inc 1 Dec 1976 [24 Dec 1975] 50158/76 Heading B3D A cylindrical grinder for simultaneously effecting stock removal from a plurality of work diameters D of a rotating driven workpiece W comprises a grinding wheel assembly having a plurality of grinding wheels W, means for advancing the wheels towards the workpiece from a predetermined first position to a predetermined second position at a selected feed rate, a workrest assembly operatively associated with a central work diameter and including upper and lower workrest jaws 14, 16, means for incrementally displacing the upper jaw towards the central diameter, means for sensing non-linearity of the workpiece, and means conjointly de-energizing the advancing means and energizing the incrementally displacing means during advancement of the grinding wheels from the first to the second positions when the magnitude of the non-linearity sensed by the sensing means exceeds a predetermined maximum value. The grinding wheels are advanced hydraulically from a retracted position to a forward position and then advanced by an electrical stepping motor to a final position at selected feed rates followed by dwell periods and spark out. Workrests having upper and lower jaws 14, 16 are associated with the ends and centre of the workpiece, the upper jaws being advanced by hydraulic cylinders 22 displacing button elements 24 engaging the jaws, and the lower jaws being advanced by hydraulic cylinders 26 moving camming elements 28 engaging the jaws. The upper jaw of the central workrest is also advanceable by a button 38 on a plunger 30 in threaded engagement with a spindle 48 rotatable by gearing 54, 56 driven by a second electric stepping motor. Size gauges 60 are associated with the ends and centre of the workpiece. In operation, the grinding wheel assembly is advanced from the fully retracted position to a forward position. The grinding assembly stepping motor is then driven to effect a sidewall feed until the grinding wheels are at a predetermined sidewall feed end point. The stepping motor is thereafter driven to effect a fast approach of the grinding wheels so that they engage the workpiece and a load control relay is actuated to advance the gauges 60 into engagement with the workpiece. The central workrest stepping motor is also actuated at the commencement of the sidewall feed to advance the upper jaw at a rapid rate to a ready position prior to the action of the load control relay which also causes the grinding wheel assembly stepping motor to advance the grinding wheels at a first feed rate and the central workrest stepping motor to advance the upper jaw until a first gauge contact closes, the workrest stepping motor continuing to operate if there is a differential signal between the end and central gauges as a result of non-linearity of the workpiece caused by bowing or wear of the grinding wheels. When the differential signal is removed, the grinding wheel assembly is again advanced until the end of the first feed. If a differential signal is generated during the feed, the feed of the assembly is stopped and the workrest stepping motor actuated to remove the differential signal. At the end of a dwell following feed at the first rate, the assembly is advanced at a second feed rate, the workrest stepping motor advancing the upper jaw whenever the differential signal appears. The hydraulic cylinders 22, 26 are actuated to advance the upper and lower jaws to a fixed point at the beginning of a second dwell at the end of the second feed, the central workrest stepping motor being reset at the end of the second dwell. At the end of the second dwell, the grinding wheel assembly is advanced at a fine feed rate until a gauge contact terminates the feed, resets the hydraulic cylinders and spark out beams.