Each jaw includes a master jaw with serrations and a top jaw, with serrations, to be fastened to a T-nut. The support groove includes a first keyway into which the key is fitted, whereas the top jaw includes a second keyway into which a tip of the key is fitted. A gap exists between the key and each of the first keyway and the second keyway. The key is inclined or twisted with respect to both the first keyway and the second keyway.

A chuck mechanism of the present invention includes multiple master jaws placed movably in a radial direction on a front surface of a chuck body, and top jaws each detachably attached to front surfaces of the top jaws. Each master jaw and each top jaw have a raised portion and a recessed portion engageable with each other. Each of the raised and recessed portions has conical surfaces formed by part of a conical body. Each top jaw has a gripping surface formed by part of a circular columnar body. Upon work gripping, the center axes of the conical surfaces on a gripping side among the conical surfaces of each master jaw and each top jaw and the center axis of the gripping surface are all coincident with a rotation axis of the chuck body.

A securement device for a press tool including an angular exterior body having a side wall. A multitude of ratcheting bodies are located around a top edge of the exterior body. The ratchets include a ratchet bar. The ratchet bar has a plurality of ratchet grooves that allow the ratchet bars to be slide inward toward the interior of the exterior body and to be locked into place. An interior body is located within the exterior body such that it can be moved about and provide extra support for the ratchets.

Each jaw includes a master jaw with serrations and a top jaw, with serrations, to be fastened to a T-nut. The support groove includes a first keyway into which the key is fitted, whereas the top jaw includes a second keyway into which a tip of the key is fitted. A gap exists between the key and each of the first keyway and the second keyway. The key is inclined or twisted with respect to both the first keyway and the second keyway.

A chuck mechanism of the present invention includes multiple master jaws placed movably in a radial direction on a front surface of a chuck body, and top jaws each detachably attached to front surfaces of the top jaws. Each master jaw and each top jaw have a raised portion and a recessed portion engageable with each other. Each of the raised and recessed portions has conical surfaces formed by part of a conical body. Each top jaw has a gripping surface formed by part of a circular columnar body. Upon work gripping, the center axes of the conical surfaces on a gripping side among the conical surfaces of each master jaw and each top jaw and the center axis of the gripping surface are all coincident with a rotation axis of the chuck body.

A projecting part 11A and a recessed part 12A which engage with each other are formed on a master jaw 11 and a top jaw 12. In the master jaw 11, a movable pin 20 movable in an axial direction and a shaft 30 movable in a radial direction is disposed, and the movable pin 20 is engaged with the shaft so that the movable pin 20 can be moved in the axial direction. The top jaw 12 is provided with a pin hole 12c into which the movable pin 20 can be inserted. The movable pin 20 is locked, by rotating the shaft 30 by a predetermined amount, at a first position in which the movable pin 20 is inserted in the pin hole 12c or at the second position in which the movable pin 20 is extracted from the pin hole 12c.

A stair form member attached jaw is installed with the stair form member provided at the bottom face of the soft jaw. The stair form member is held between a pair of grips in the jaw installing groove of the master jaw from both sides of the radial direction, thereby pulling the stair form member to the bottom direction of the jaw installing groove. The position of the radial direction of the soft jaw is determined by the engagement between the bottom face of the soft jaw and the upper serration faces of the master jaw; and the position of the soft jaw in the tangent line is determined by the close contact of the stair form member to the side face of the jaw installing groove.

Intrusion of chips is prevent into gaps formed between inner end surfaces of master jaws and a chuck cover. A top plate is disposed at the center of an end surface of a chuck body. Top covers, which move in conjunction with movements of master jaws when opening and closing the chuck, are disposed in top cover guide recesses formed at three positions on the top plate. Each top cover abuts the center-side end parts of serrated surfaces formed on both widthwise sides of a respective master jaw and the center-side end part of a step section of a stepped claw therebetween, and the top covers close gaps formed at the center-side end parts by the movements of the master jaws at all times by moving in conjunction with movement of the master jaws.

Backing and clamping chuck jaw part (110, 120), respectively, arranged to engage with each other such that respective contact surfaces (113, 123) a rearranged to come into contact with each other so as to together form a chuck jaw (100) for a chuck (10). The invention is characterized in that the backing chuck jaw part is manufactured from a harder metal material than a metal material from which the clamping chuck jaw part is manufactured, in that a the backing chuck jaw part comprises a convex structure (126), and in that the convex structure is arranged to engage with a corresponding concave structure (116) of the clamping chuck jaw part so that the said concave structure is permanently deformed as a result of an engagement between said structures resulting from the chuck jaw parts first being arranged in a contacting orientation and thereafter being pressed together into an engagement orientation, in which contact is established between said contact surfaces. The invention also relates to a chuck jaw, a chuck and a method.

A chuck for mounting workpiece is disclosed. A chuck for mounting workpiece includes a chuck body; and a base jaw mounted on the chuck body. The chuck body includes an aluminum alloy. The chuck body includes an aluminum alloy having specific gravity smaller than that of alloy steel for machining structural use or carbon steel for machine structure use. Thus, the chuck can be light weight.