POSITIONING METHOD FOR HOLLOW WORK-PIECE

PROBLEM TO BE SOLVED: To provide a positioning method for a hollow work-piece that can easily position a hollow work-piece which is subjected to lathe-machining at an arbitrary position regardless of variations in size of the hollow work-piece, and machine both end parts and an outer diameter part of the hollow work-piece at the same time without re-gripping the work-piece.SOLUTION: In the positioning method for a hollow work-piece 5, both end surfaces of the hollow work-piece 5 are gripped by inner diameter gripping chucks 4 at both sides and contacted with the surfaces both contact surfaces 72a and 72a of the inner diameter gripping chucks 4, so as to measure a length in a shaft direction of the hollow work-piece 5; and the gripping by one chuck 4 is released, the other chuck 4 gripping the hollow work-piece 5 is moved in a direction in which the other chuck separates from the one chuck 4, the hollow work-piece 5 is gripped by the one chuck 4, the gripping by the other chuck 4 is released, then the other chuck 4 is moved in the direction in which the other chuck separates from the one chuck 4, and the hollow work-piece 5 is gripped by the other chuck 4.SELECTED DRAWING: Figure 6 【課題】中空ワークの大きさにばらつきがある場合でも旋盤に対する中空ワークを任意の位置に容易に位置決めすることができ、掴みかえることなく中空ワークの両端部および外径部を同時に加工することができる中空ワークの位置決め方法を提供する。【解決手段】中空ワーク5の位置決め方法は、中空ワーク5の両端面を両側の内径把持用チャック4で把持するとともに内径把持用チャック4の両当接面72a,72aに当接させて、中空ワーク5の軸方向の長さを計測する。前記一方のチャック4の把持を解放し、中空ワーク5を把持した状態の前記他方のチャック4を前記一方のチャック4から離れる方向に移動させ、前記一方のチャック4で中空ワーク5を把持し、前記他方のチャック4の把持を解放した後、前記他方のチャック4を前記一方のチャック4から離れる方向に移動させ、前記他方のチャック4で中空ワーク5を把持する。【選択図】図６