Patent ID: 8613434
Filing Date: 2013-12-24
Classification: B23Q

Abstract:
1. A work pallet positioning and fixing device comprising: a ring member that is provided to a work pallet; a base member to which the ring member can engage from above; and a clamp mechanism for fixing the ring member to the base member; and wherein the base member positions the ring member with respect to the base member in a vertical direction and a horizontal direction and also restrains rotation of the ring member with respect to the base member about a vertical axis; wherein the base member comprises a vertical axis, Z reference surfaces for stopping a lower end reference surface of the ring member to position the ring member in the vertical direction, and a tapered male engagement portion whose horizontal cross section is formed as a regular polygon that has a plurality of circular arcuate vertex portions that are convex outward and a plurality of side portions, and which reduces in diameter upwards, and the tapered male engagement portion is formed integrally with the base member; wherein the ring member comprises a vertical axis and a tapered female engagement portion that is formed to be capable of engaging with the tapered male engagement portion so that the lower end reference surface comes into contact against the Z reference surfaces, and moreover whose horizontal cross section is formed as a regular polygon that has a plurality of circular arcuate vertex portions that are convex outward and a plurality of side portions, and the tapered female engagement portion is formed integrally with the ring member; wherein the tapered female engagement portion is adapted to engage in close contact with the tapered male engagement portion, by elastic deformation in a radial direction of at least one of an external circumferential side wall portion of the tapered female engagement portion and the internal circumferential side wall portion of the tapered male engagement portion; wherein the clamp mechanism comprises a hydraulic cylinder for clamping and a ball lock mechanism which is provided on the base member and the ring member; wherein the ball lock mechanism comprises a barrel portion formed at an upper end portion of the base member and inserted into a circular aperture in the ring member; a plurality of ball reception holes formed in the barrel portion; a plurality of balls, each of which is held in one of the plurality of ball reception holes and is movable in the radial direction; a plurality of ball reception grooves formed on an internal circumferential portion of the upper end portion of the ring member, so as to correspond to the plurality of ball reception holes, wherein the plurality of ball reception grooves receives the plurality of balls; a circular plate member provided at an upper end portion of a piston rod of the hydraulic cylinder and disposed to slide freely up and down in the barrel portion; and a plurality of inclined portions for ball driving and a plurality of concave portions for ball retraction formed on an external circumferential portion of the circular plate member so as to correspond to the plurality of ball reception holes; and wherein the tapered male engagement portion is positioned more to the radial interior than a conical surface that contains the plurality of balls and centers in the radial directions of the Z reference surfaces.