Ni-Ti계 합금 튜브의 레이저 정밀가공 특성에 미치는 공정조건의 영향

Abstract

The effect of working parameters such as laser power and travel speed on the laser-cutting characteristics of Ni-Ti based alloy tubes have been investigated. The transformation characteristics and pseudoelasticity of slotted tube also have been studied. The results obtained are as follows; (1) The cutting quality of tube depends on laser power and travel speed; Ni-Ti tube is not cut completely and slotted parts are not separated at 13W due to lower energy density even though lower travel speed. However, the tube can be cut completely and then slotted parts can be separated at 14W. In the case of laser power of 15W, the tube can be cut completely but the tube slotted by laser is deformed because of higher laser power than 13W and 14W. (2) The slotted width of tube by laser cutting is about 25 ～ 40㎛. The width is decreased with increasing laser power or travel speed; the width is 27 ～ 32㎛ at 13W, 29 ～ 36㎛ at 14W and 30 ～ 39㎛ at 15W, respectively. (3) Transformation temperature of slotted tube is shifted to lower temperature, compared with that of as-received tube and the temperature drop is increased with and increasing laser power and decreasing travel speed. (4) The slotted tube is annealed at different temperatures in order to remove to internal stress induced during laser cutting and then expanding slotted tube, the annealing condition of 500℃×10min is suitable for expanding slotted tube. (5) Slotted Ni-Ti tubes(OD: 3.2㎜ WT: 200㎛) is electro-polished by using a mixture of HClO4 ＋ Ch3COOH solutions at temperature range of 10 to 30℃ and at voltages of 10 to 25V for 10sec. Mirror plane without pits and orange peel can be obtained at the electric power of 20V and electrolyte temperature of 20℃.