Patent ID: 7694799

Claim:
An automatic pallet exchanger of a machine tool for exchanging a pallet located in a processing area with a pallet located in a waiting area, comprising: an APC body; a cylinder having an outer circumference and an end which is fixed to the APC body; a movable unit supported on the APC body and the cylinder and including an elevating cylinder housing, which surrounds at least a portion of the cylinder and which includes an inner circumference, a piston, which extends through the cylinder, an APC driving shaft, which extends through at least a portion of the piston, and an APC arm, which is fixed to the elevating cylinder housing for supporting a pallet thereon, the movable unit being rotatable and elevatable relative to the APC body and the cylinder for moving a pallet supported on the APC arm; an upper bearing interposed between the outer circumference of the cylinder and the inner circumference of the elevating cylinder housing; and a lower bearing provided below the upper bearing between a lower portion of the APC driving shaft and the APC body, the upper and lower bearings rotatably and elevatably supporting the movable unit on the cylinder and the APC body, respectively, so as to permit rotational and elevating movements of the movable unit, the upper and lower bearings providing two bearing points for counteracting an unbiased load applied to the APC arm so as to inhibit the APC driving shaft from undergoing partial side wear, wherein the APC arm further comprises: a stopper fixed beneath the APC driving shaft; and stopping means fixed to the APC body for stopping the rotation of the APC arm at a fixed position.