The present invention provides, in one aspect, a rotating power tool including a housing, a drive unit within the housing having an electric motor defining a rotational axis, and a drive shaft coupled to the electric motor to receive torque therefrom configured to rotate about the rotational axis, the drive shaft having an eccentric portion. The drive unit further includes an accessory tool configured to orbit about the rotational axis in response to rotation of the eccentric portion of the drive shaft, the accessory tool defining a rotational imbalance. The rotating power tool further includes a dynamic mass balancing system including an actively adjustable counterbalance mass to attenuate vibration caused by the rotational imbalance.

A grinding apparatus includes grinding wheel side vibrational displacement calculation devices that obtain a vibrational displacement of a grinding wheel resulting from a vibration in an approaching/separating direction of the grinding wheel; main spindle side vibrational displacement calculation devices that obtain a vibrational displacement of a workpiece generated by propagation of the vibration in the approaching/separating direction of the grinding wheel; a relative vibrational displacement calculation unit that obtains a relative vibrational displacement between the grinding wheel and the workpiece based on the vibrational displacement of the grinding wheel and the vibrational displacement of the workpiece that have been obtained; a position change unit that creates, based on the obtained relative vibrational displacement between the grinding wheel and the workpiece, a position change command to change a position of the wheel spindle stock; and a processing controller that grinds the workpiece W based on the created position change command.

An embodiment of a tool assembly includes a hub connected to a distal end of a spring-loaded shaft assembly disposed along a first axis. An upper hub portion is adjacent to the distal end of the spring-loaded shaft assembly aligned with the first axis, and a lower hub portion extends along a second axis, forming a nonzero angle relative to the first axis. A roller disk is joined to the lower portion of the hub, and is rotatable about the second axis parallel to the second portion of the hub. A load cell is disposed along the first axis between a proximal end of the shaft and the roller disk, and is adapted to measure a downward force applied along the shaft assembly.

A resurfacing machine that includes a spindle carrying a resurfacing tool and an electric motor operatively connected to the spindle and configured to rotate the spindle about an axis. The machine includes a control system, such as a processor and a computer readable medium carrying spindle control instructions thereon. The control system is configured to control the operation of the motor in order to rotate the spindle through a repeating acceleration and deceleration cycle during a resurfacing operation.

A polishing apparatus capable of preventing wear of rollers which are to transmit a load to a retainer ring and capable of preventing wear particles from escaping outside is disclosed. The polishing apparatus includes: a retainer ring disposed so as to surround the substrate and configured to press the polishing surface while rotating together with a head body; a rotary ring secured to the retainer ring and configured to rotate together with the retainer ring; a stationary ring disposed on the rotary ring; and a local-load exerting device configured to apply a local load to a part of the retainer ring through the rotary ring and the stationary ring. The rotary ring has rollers which are in contact with the stationary ring.

Provided is a vibration-proof structure capable of more effectively reducing rotational vibration of a rotating body during a cutting operation. According to a configuration of the structure, inside a main body of the rotating body, there are provided a plurality of shaft members arranged along a longitudinal direction of a rotation axis of the rotating body and at least one layer of multiple tubular members fitted over the shaft members and arranged coaxially with the rotation axis along the longitudinal direction of this rotation axis; and a boundary position between the shaft members adjacent each other in the longitudinal direction and a boundary position between the tubular members adjacent each other in the longitudinal direction are set as different positions along the longitudinal direction.

A grinding apparatus includes a holding table for holding a wafer, a support table for supporting the holding table, a motor for rotating the support table, a frame member supporting the support table for rotation, and at least three support poles for supporting the frame member from the base. Each of the support poles has formed in the inside thereof a through-hole, a supply port which communicates the through-hole and an air supply source with each other, and an exhaust port which exhausts air having flowed through the through-hole toward the support table. Air is supplied into the through-hole to cool the support pole, and the air having flowed through the through-hole is exhausted toward the support table.

A handheld power tool device for a handheld power tool, in particular a sander, preferably an orbital sander or a random orbital sander includes a housing unit, which has a handle housing and a drive housing for holding a drive unit. The drive housing defines a drive axis of the drive unit. The power tool device further includes a damping unit which couples the drive housing to the handle housing. The drive housing includes an extension arm, which extends at least radially with respect to the drive axis and on which at least a portion of the damping unit is arranged.

An evolutionary compensation method for a spindle rotation error of a CNC grinding machine is provided. Feature points are determined at an edge of a central hole of a spindle of a CNC grinding machine, and a spindle rotation error in-situ measuring device is fixed on the grinding machine and aligned with the edge of the central hole; a trajectory image of the feature points is acquired by using the measuring device; a measured value of the spindle rotation error is obtained according to the trajectory image; features of the spindle rotation error are fused with the measured value of the spindle rotation error, a spindle rotation error compensation model is established, to output a spindle rotation error compensation value, thereby compensating the spindle rotation error. By continuously calibrating the error model using the measured value, accuracy of the error model has been continuously optimized.

Provided is a vibration-proof structure capable of more effectively reducing rotational vibration of a rotating body during a cutting operation. According to a configuration of the structure, inside a main body of the rotating body, there are provided a plurality of shaft members arranged along a longitudinal direction of a rotation axis of the rotating body and at least one layer of multiple tubular members fitted over the shaft members and arranged coaxially with the rotation axis along the longitudinal direction of this rotation axis; and a boundary position between the shaft members adjacent each other in the longitudinal direction and a boundary position between the tubular members adjacent each other in the longitudinal direction are set as different positions along the longitudinal direction.