Multiple holding surfaces of a chuck table are disposed in such a manner that the heights thereof from a reference surface are in increasing order along a first direction parallel to each of them. Thus, in a case of using this chuck table, creep-feed grinding for workpieces each held by a respective one of the multiple holding surfaces can be executed in states in which a grinding unit is positioned at different heights. In this case, the workpiece for which the creep-feed grinding has been executed is located on the lower side as viewed from the grinding unit when another workpiece is ground. Due to this, in this creep-feed grinding, a specific workpiece can be prevented from being ground twice.

A square bar grinding device includes a loading rack, a clamping device, a grinding device, and a grinding tool grinding device. The loading rack is provided with stations, the stations include a first station and a second station, the first station is used for placing a to-be-machined square bar, the grinding tool grinding device includes an oil stone assembly, the oil stone assembly is disposed at the second station, and the clamping device is used for clamping and transferring the to-be-machined square bar or the oil stone assembly in the stations of the loading rack to the grinding device. According to the square bar grinding device, a grinding tool grinding device is disposed at a loading rack, and can be clamped and transferred by a clamping device to be quickly moved to a grinding device for grinding of a grinding tool.

A square bar grinding device includes a loading rack, a clamping device, a grinding device, and a grinding tool grinding device. The loading rack is provided with stations, the stations include a first station and a second station, the first station is used for placing a to-be-machined square bar, the grinding tool grinding device includes an oil stone assembly, the oil stone assembly is disposed at the second station, and the clamping device is used for clamping and transferring the to-be-machined square bar or the oil stone assembly in the stations of the loading rack to the grinding device. According to the square bar grinding device, a grinding tool grinding device is disposed at a loading rack, and can be clamped and transferred by a clamping device to be quickly moved to a grinding device for grinding of a grinding tool.

A grinding machine includes a main part and an end case. A driving unit is connected to the end case and includes a first motor which has an output shaft with a groove. A grinding unit is connected to the end case, and cantilevered above the main part. The grinding unit includes a grinding wheel set which has a central axle with a slide. The slide is located in the groove of the output shaft of the first motor. A driving wheel is connected to the central axle. An adjustment device includes a second motor which drives an eccentric unit that has an eccentric axle, and the eccentric axle extends through a bearing which is located in a recess formed to the driving wheel. The driving wheel is driven by the eccentric unit to move the grinding wheel set of the grinding unit left and right.

A grinding wheel includes an annular base, a plurality of pipe grindstones annularly arranged on the annular base, and a grinding water supply unit that supplies grinding water to the pipe grindstones. The grinding water supply unit includes a ring-shaped grinding water retaining part formed between a mount surface and an opposite surface of the annular base, a plurality of water supply holes opening in the mount surface, and a plurality of water feeding holes formed to allow communication between the grinding water retaining part and an inside of each of the pipe grindstones.

A grinding wheel includes an annular base, a plurality of pipe grindstones annularly arranged on the annular base, and a grinding water supply unit that supplies grinding water to the pipe grindstones. The grinding water supply unit includes a ring-shaped grinding water retaining part formed between a mount surface and an opposite surface of the annular base, a plurality of water supply holes opening in the mount surface, and a plurality of water feeding holes formed to allow communication between the grinding water retaining part and an inside of each of the pipe grindstones.

A method for grinding a plate-formed workpiece having a raised center with a grindstone is provided. The method includes a first holding process including suctioning and holding the plate-formed workpiece against a holder surface of a first chuck table, which is in a shape where a center is raised with respect to an outer circumference thereof; a reaction-force reducing grinding process including grinding a central part of the plate-formed workpiece with the grindstone to reduce a reaction force against a flattening force to be applied to the plate-formed workpiece; a second holding process including suctioning and holding the plate-formed workpiece against a holder surface of a second chuck table, which spreads in parallel to a lower surface of the grindstone; and a finish-grinding process including grinding to finish the plate-formed workpiece with the grindstone.

A method for grinding a plate-formed workpiece having a raised center with a grindstone is provided. The method includes a first holding process including suctioning and holding the plate-formed workpiece against a holder surface of a first chuck table, which is in a shape where a center is raised with respect to an outer circumference thereof; a reaction-force reducing grinding process including grinding a central part of the plate-formed workpiece with the grindstone to reduce a reaction force against a flattening force to be applied to the plate-formed workpiece; a second holding process including suctioning and holding the plate-formed workpiece against a holder surface of a second chuck table, which spreads in parallel to a lower surface of the grindstone; and a finish-grinding process including grinding to finish the plate-formed workpiece with the grindstone.

Stored is a height of a grinding mechanism when lower surfaces of grinding stones have come into contact with an upper surface of a wafer held on a holding surface, through lowering of the grinding mechanism from above the wafer. Based on this height, an origin point height which is a height of the grinding mechanism when the lower surfaces of the grinding stones have come into contact with the holding surface is then determined.

An oscillating spindle sander assembly and a method for manufacturing an oscillating spindle sander assembly are provided. The assembly includes an oscillating spindle sander. The oscillating spindle sander includes an oscillation generator, a drive shaft extending from the oscillation generator, and a table disposed above the oscillation generator and having an opening that accommodates the drive shaft. The oscillating spindle sander assembly further includes a rotary compartment drum rotatably mounted under the table and around the oscillation generator. The rotary compartment drum includes a plurality of storage compartments arranged around a circumference of the rotary compartment drum.