Abstract: In a grinding machine, either the revolutional speed of the workpiece or of the grinding wheel is controlled and further the infeed speed of the wheel to the workpiece is controlled so that the optimum grinding condition, having a suitable ratio of the workpiece surface speed to the grinding wheel surface speed and a suitable ratio of the infeed speed to the workpiece revolutional speed, is obtained. The former ratio is maintained despite the wheel diameter decrease caused by wheel dressings.

Abstract: A preloaded bearing comprises a spindle which is rotatably supported in the bore of a housing by a pair of ball bearings near one end of the bore and a second pair of ball bearings near the other end of the bore. One pair of ball bearings is axially slidable in the bore and is preloaded by a compression spring acting between the bearings and an abutment in the bore. The spindle is driven by a belt which runs on a pulley at one end of the bore and thereby subjects the spindle to a radial load. A recess is provided in the wall of the bore on the radially loaded side of the slidable pair of bearings and pressurized fluid is supplied to the recess so as to exert fluid pressure in a direction opposing the load applied by the belt. The pressurized fluid is preferably lubricating oil and is supplied not only to the recesses but also to the bearings in order to lubricate them.

Abstract: An apparatus for feed grinding workpieces comprises a workpiece spindle assembly for supporting a workpiece and a grinding wheel spindle assembly for supporting a grinding wheel, the two spindle assemblies being movable relative to each other to enable movement of the workpiece into pressure contact with the grinding wheel. A variable speed drive system rotationally drives the grinding wheel relative to the workpiece at a first predetermined speed of rotation different than the resonant frequency of the grinding wheel spindle assembly to effect feed grinding of the workpiece. Completion of the feed grinding or spark-out is detected after which the rotational speed of the grinding wheel is lowered to a second predetermined speed different than the resonant frequency of the grinding wheel spindle assembly when operating in the spark-out mode. The high speed rotation during feed grinding assures good grinding quality and the low speed rotation during spark-out assures good surface finishing.

Abstract: A method of feed grinding workpieces comprises moving a workpiece into pressure contact with a grinding wheel and rotationally driving the grinding wheel relative to the workpiece at a predetermined speed of rotation different than the resonant frequency of the grinding wheel spindle assembly to effect feed grinding of the workpiece. Completion of the feed grinding or spark-out is detected after which the rotational speed of the grinding wheel is lowered to another predetermined speed different than the resonant frequency of the grinding wheel spindle assembly when operating in the spark-out mode. The high speed rotation during feed grinding assures good grinding quality and the low speed rotation during spark-out assures good surface finishing. By rotating the grinding wheel spindle assembly at speeds other than its resonant frequencies, damage due to large vibrations of the assembly is avoided.

Abstract: A spindle assembly has a rotatable spindle which is electrically insulated from its housing by means of a moulded synthetic resin layer surrounding bearing holders. Electric current for effecting electrolytic grinding is supplied by a brush member which is in contact to the rear end of the spindle, the contact portion of the spindle and the brush having air circulating pathes for cooling and ejecting out powdered-brush-material and have radiating surfaces exposed to cooling air flow.

Abstract: A grinding apparatus has an in-process sizing device to measure a size of a workpiece under grinding, and a detecting device to measure the location of the infeed table on which a grinding wheel is mounted to grind the workpiece. The outputs of the in-process sizing device and of the detecting device are so calculated that the amount of residual stock-removal on the workpiece is computed out as the difference between in-feed amount of the wheel head and actual stock-removal amount on the workpiece which is continuously measured by the in-process sizing device. The computed residual stock-removal is compared with a pre-set value which is selected from a series of pre-set values for various grinding steps such as a rough grinding step or a fine grinding step, in response to the workpiece size measured by the in-process sizing device.