An annular grindstone includes a grindstone section that includes a binder and abrasive grains dispersed and fixed in the binder, in which the binder includes a tin-nickel alloy. Preferably, a content of tin in the tin-nickel alloy is equal to or more than 57 wt % and less than 75 wt %. In addition, preferably, the annular grindstone consists of the grindstone section. Alternatively, the annular grindstone further includes an annular base having a grip section, and the grindstone section is exposed to an outer peripheral edge of the annular base.

A grinding wheel center hole protection pad is provided, which mainly include a positioning portion attached to the peripheral thereof and the guiding portions disposed at the center hole at the axial center thereof. The guiding portions serve as the isolation layer between the center hole of the grinding wheel and the peripheral plate guiding wall of a flange plate. Therefore, the grinding wheel can be closely attached to the flange plate during the assembling process to decrease eccentricity. Accordingly, it is not necessary to perform the cutting calibration process and balance adjustment by a cutting machine, which can reduce the waste of manpower and material resources.

A hubbed blade to be mounted on a spindle includes a circular hub and a circular blade fixed on a side of a first side of the hub. The blade has an opening formed through its center. The hub includes a protrusion portion protruding from the first side and having an outer peripheral edge of a shape corresponding to a shape of the opening. The hub and the blade are connected together via an adhesive with the hub and the blade being aligned each other with the protrusion portion inserted in the opening.

A hubbed blade to be mounted on a spindle includes a circular hub and a circular blade fixed on a side of a first side of the hub. The blade has an opening formed through its center. The hub includes a protrusion portion protruding from the first side and having an outer peripheral edge of a shape corresponding to a shape of the opening. The hub and the blade are connected together via an adhesive with the hub and the blade being aligned each other with the protrusion portion inserted in the opening.

A hubbed blade to be mounted on a spindle includes a circular hub having an opening formed through a center thereof, and a circular blade fixed on a side of a first side of the hub. The hub has a first raised portion and a second raised portion. The first raised portion is circular, is disposed along an outer peripheral edge of the hub, and protrudes from the first side of the hub. The second raised portion is disposed so as to surround the opening on an inner side than the first raised portion in a radial direction of the hub, and protrudes from the first side of the hub. The hub and the blade are connected together via an adhesive applied to a plurality of regions on an end face of the second raised portion.

A hubbed blade to be mounted on a spindle includes a circular hub having an opening formed through a center thereof, and a circular blade fixed on a side of a first side of the hub. The hub has a first raised portion and a second raised portion. The first raised portion is circular, is disposed along an outer peripheral edge of the hub, and protrudes from the first side of the hub. The second raised portion is disposed so as to surround the opening on an inner side than the first raised portion in a radial direction of the hub, and protrudes from the first side of the hub. The hub and the blade are connected together via an adhesive applied to a plurality of regions on an end face of the second raised portion.

A circular saw mounting device which rotatably supports a saw blade in a grinding machine is disclosed. The mounting device comprises a base plate adapted for mounting in a grinding machine; a centering element comprising at least two engagement elements configured to be operated in a radial direction between a mounting position and a locking position. According to the invention the mounting device further comprises an actuator comprising a pin being configured to be operated in an axial direction and arranged to engage with pivot articulated couplings to each of the engagement elements to thereby transfer a radial displacement to the at least two engagement elements and to thereby operate the at least two engagement elements between the mounting position and the locking position.

A circular saw mounting device which rotatably supports a saw blade in a grinding machine is disclosed. The mounting device comprises a base plate adapted for mounting in a grinding machine; a centering element comprising at least two engagement elements configured to be operated in a radial direction between a mounting position and a locking position. According to the invention the mounting device further comprises an actuator comprising a pin being configured to be operated in an axial direction and arranged to engage with pivot articulated couplings to each of the engagement elements to thereby transfer a radial displacement to the at least two engagement elements and to thereby operate the at least two engagement elements between the mounting position and the locking position.

A cleaning device for cleaning and/or polishing a surface having an aperture, such as a wheel rim contact surface of a motor vehicle or the like, comprises a housing, which has a rear rotary portion for rotating the housing about a rotational axis and a front fastening portion for releasably fastening a cleaning body; the cleaning body comprising a stabilising plate which faces the housing and has a centring pin that faces away from the housing and projects centrically towards the outside, and a cleaning means that covers the surface of the stabilising plate that faces away from the housing; and the fastening portion and the stabilising plate each having a corresponding connecting means for rotationally stable connection to one another.

A cleaning device for cleaning and/or polishing a surface having an aperture, such as a wheel rim contact surface of a motor vehicle or the like, comprises a housing, which has a rear rotary portion for rotating the housing about a rotational axis and a front fastening portion for releasably fastening a cleaning body; the cleaning body comprising a stabilising plate which faces the housing and has a centring pin that faces away from the housing and projects centrically towards the outside, and a cleaning means that covers the surface of the stabilising plate that faces away from the housing; and the fastening portion and the stabilising plate each having a corresponding connecting means for rotationally stable connection to one another.