A tool driver for a power trowel, the tool driver comprising a combination of a magnetic fastening arrangement and a friction based fastening arrangement for releasably holding an abrasive tool to the tool driver, wherein the magnetic fastening arrangement is configured symmetrically around a rotational center of the tool driver, wherein the friction based fastening arrangement is adapted to provide increased shear strength during abrasive operation of the tool, and wherein the magnetic fastening arrangement is adapted to provide increased pull strength during lifting of the tool driver.

An abrasive disc (2) for grinding and/or polishing hard floor surfaces of stone, concrete or similar, the abrasive disc including a plurality of fixing means (3, 4) for mounting detachably mountable carrier plates (9), each with abrasive elements (11), to a grinding side (2a) of the abrasive disc (2), each carrier plate having a specific fixing geometry, characterized by that the fixing means are disposed at least two separate distances from the centre of the disc, first fixing means (3) at a first predetermined distance (r1) and second fixing means (4) at a second predetermined distance (r2), said second predetermined distance (r2) being shorter than the first (r1), so that the carrier plates (9) will be arranged in at least to rows, a first outer row and a second inner row, and each fixing mean (3, 4) includes a groove (7) providing a female coupling adapted for corresponding male couplings of the carrier plates (9).

An abrasive disc (2) for grinding and/or polishing hard floor surfaces of stone, concrete or similar, the abrasive disc including a plurality of fixing means (3, 4) for mounting detachably mountable carrier plates (9), each with abrasive elements (11), to a grinding side (2a) of the abrasive disc (2), each carrier plate having a specific fixing geometry, characterized by that the fixing means are disposed at least two separate distances from the centre of the disc, first fixing means (3) at a first predetermined distance (r1) and second fixing means (4) at a second predetermined distance (r2), said second predetermined distance (r2) being shorter than the first (r1), so that the carrier plates (9) will be arranged in at least to rows, a first outer row and a second inner row, and each fixing mean (3, 4) includes a groove (7) providing a female coupling adapted for corresponding male couplings of the carrier plates (9).

A polishing apparatus includes a rotatable head body having a pressing surface, a retainer ring configured to press a polishing surface while rotating together with the head body, a stationary ring, local load applying devices configured to apply a local load to the stationary ring, and a controller. The local load applying devices include a first pressing member and a second pressing member connected to the stationary ring. The first pressing member is disposed in the upstream side of the retainer ring in the traveling direction of the polishing surface, and the second pressing member is disposed in the downstream side. The controller calculates the inclination angle of the stationary ring based on a measured value of the height of at least one of the first pressing member and the second pressing member.

A polishing apparatus includes a rotatable head body having a pressing surface, a retainer ring configured to press a polishing surface while rotating together with the head body, a stationary ring, local load applying devices configured to apply a local load to the stationary ring, and a controller. The local load applying devices include a first pressing member and a second pressing member connected to the stationary ring. The first pressing member is disposed in the upstream side of the retainer ring in the traveling direction of the polishing surface, and the second pressing member is disposed in the downstream side. The controller calculates the inclination angle of the stationary ring based on a measured value of the height of at least one of the first pressing member and the second pressing member.

A method of grinding a workpiece includes a holding step of holding the workpiece on a flat holding surface of a holding table and a grinding step of rotating a grinding wheel to turn grindstones along an annular track while rotating the holding table, and bringing the grindstones into grinding contact with an upper surface of the workpiece to thereby grind the workpiece. The grinding step includes the step of bringing the grindstones into grinding contact with the upper surface of the workpiece in a state where the annular track is closest to the holding surface in an area between a point above a center of the holding surface and a point above an outer circumferential end of the holding surface.

A driver interface for a grinding head includes a center plate having top and bottom surfaces, an outer edge, a mounting channel in the top surface, and mounting pads on the bottom surface, each pad having a raised edge. An upper clamping plate is inserted within the mounting channel. A lower clamping plate defines disk locating apertures and fastens to the bottom surface of the center plate so that each of the disk locating apertures surround the raised edge of a mounting pad. The upper and lower clamping plates are removably fastened to the center plate. A disk attacher having an anchoring portion and a disk receiving portion bends around the outer edge of the center plate so that the upper clamping plate when fastened to the center plate clamps the anchoring portion between the upper clamping plate and the mounting channel, and so that the lower clamping plate when fastened to the center plate clamps the disk receiving portion to a mounting pad and within one of the disk locating apertures.

A driver interface for a grinding head includes a center plate having top and bottom surfaces, an outer edge, a mounting channel in the top surface, and mounting pads on the bottom surface, each pad having a raised edge. An upper clamping plate is inserted within the mounting channel. A lower clamping plate defines disk locating apertures and fastens to the bottom surface of the center plate so that each of the disk locating apertures surround the raised edge of a mounting pad. The upper and lower clamping plates are removably fastened to the center plate. A disk attacher having an anchoring portion and a disk receiving portion bends around the outer edge of the center plate so that the upper clamping plate when fastened to the center plate clamps the anchoring portion between the upper clamping plate and the mounting channel, and so that the lower clamping plate when fastened to the center plate clamps the disk receiving portion to a mounting pad and within one of the disk locating apertures.

A driver interface for a grinding head includes a center plate having top and bottom surfaces, an outer edge, a mounting channel in the top surface, and mounting pads on the bottom surface, each pad having a raised edge. An upper clamping plate is inserted within the mounting channel. A lower clamping plate defines disk locating apertures and fastens to the bottom surface of the center plate so that each of the disk locating apertures surround the raised edge of a mounting pad. The upper and lower clamping plates are removably fastened to the center plate. A disk attacher having an anchoring portion and a disk receiving portion bends around the outer edge of the center plate so that the upper clamping plate when fastened to the center plate clamps the anchoring portion between the upper clamping plate and the mounting channel, and so that the lower clamping plate when fastened to the center plate clamps the disk receiving portion to a mounting pad and within one of the disk locating apertures.

A driver interface for a grinding head includes a center plate having top and bottom surfaces, an outer edge, a mounting channel in the top surface, and mounting pads on the bottom surface, each pad having a raised edge. An upper clamping plate is inserted within the mounting channel. A lower clamping plate defines disk locating apertures and fastens to the bottom surface of the center plate so that each of the disk locating apertures surround the raised edge of a mounting pad. The upper and lower clamping plates are removably fastened to the center plate. A disk attacher having an anchoring portion and a disk receiving portion bends around the outer edge of the center plate so that the upper clamping plate when fastened to the center plate clamps the anchoring portion between the upper clamping plate and the mounting channel, and so that the lower clamping plate when fastened to the center plate clamps the disk receiving portion to a mounting pad and within one of the disk locating apertures.