A brush assembly adapted to be rotated about an axis has a brush having a flexible, annular and generally cylindrical collar generally centered on the axis and having a predetermined and generally uniform radial thickness, a predetermined inside diameter, and a predetermined axial length, and a plurality of arrays of radially projecting bristles angularly equispaced about the collar and defining a plurality of axially throughgoing and angularly equispaced bristle-free zones. A holder drum has a core having an outer surface centered on the axis and having a predetermined outside diameter substantially smaller than the inside diameter of the collar, inner and outer end flanges axially flanking the core paced axially apart by a predetermined axial distance greater than the axial length of the collar so that the collar is received with axial play between the flanges, and respective retaining tongues extending axially between the flanges in the bristle-free zones of the brush. The tongues have inner surfaces spaced radially outward from the outer surface of the core body by a radial spacing substantially greater than the radial thickness of the collar so that the collar is received with radial play between the surfaces and the tongues.

A rotating grinding or polishing device includes a number of grinding or polishing discs formed of two or more layers of segments radiating from a central retaining area having an edge which defines a central hole. In the central area, the segments are kept together by a heat-activatable string which also maintains the grinding or polishing disc in the form of a ring, whereby the disc has the required optimum stiffness/flexibility for obtaining an effective grinding or polishing finish so that even complex surfaces can be effectively ground or polished.

A clamping device of a rotating tool includes a first clamping plate and a second clamping plate. The first clamping plate includes a snap groove disposed at the center of the first clamping plate and having a bored hole disposed at a center of the snap groove and a plurality of first fixing grooves disposed on the circumference of the first clamping plate. The second clamping plate includes a snap protrusion disposed at the center of the second clamping plate, corresponding to the snap groove, and having a bored hole disposed at a center of the snap protrusion, and a plurality of fixing protrusions disposed on the circumference of the second clamping plate and corresponding to the first fixing grooves, wherein one of the first and second clamping plates includes a plurality of union protrusions integrally formed thereon and the other one includes a plurality of second fixing grooves corresponding to the union protrusions.

A rotatively driveable tool chucking device with at least two chucking disks and a common tightening screw for chucking a tool sleeve between the two chucking disks. The chucking disks have concentric annular grooves for chucking tool sleeves with essentially the same diameter. When the sleeves are of flexible material, they are rotationally stabilized about the central axis of rotation, without requiring a rubber core or similar support body. This stabilization maintains the sleeves always in cylindrical shape.

The present invention discloses a grinding brush fixing device applying to a pneumatic tool for surface treatment. The spacing between the fixing arms and arc plates of the brush holder is reduced. Thereby, the press-fit face of the axially-extending fixing arm can press the brush collar onto the first press-fit edge and second press-fit edge, which are at two sides of the notches between two axially-extending arc plates. Further, a flexible gasket is radially placed in a space between the fixing arms and the arc plates. When the fixing disc is fastened to the brush holder, the flexible gasket and the brush collar are tightly compressed and firmly secured. Thus, force can be uniformly applied onto the brush collar and the bristles. The present invention can promote the stability of brush's rotation, generate straighter ground strips, prolong the durability of the grinding brush and grinding brush fixing device, and promote the grinding efficiency.