Fabrication Process for Ni-Ti Shape-Memory-Alloy Fine Tubes Used in Medical Tests

由于形状记忆合金细管不与生物体发生反应，在医疗和检测时可增加其扭矩传递特性，便于临床应用，同时减少患者的不适感，因此有望在医疗检测和治疗用导管和注射针中使用形状记忆合金细管。在本研究中，使用镍钛形状记忆合金，本文研究了微细管的单拉和塞拉的最佳拉深工艺条件。Ni-Ti合金是一种具有超弹性和形状记忆合金特性的优良功能材料，但与实际合金相比，其易成形性较差。因此，我们进行了研究，选择一个易于绘制润滑剂，优化的拉伸条件，包括模具角度和减少面积，明确的拉伸极限，确定形状恢复率后，以及在热处理后，以及确定的内部和外部表面粗糙度的拉制细管。本文还用有限元法对拉深过程中的应力应变分布进行了理论分析。根据所获得的结果，我们阐明了在细管横截面积减少约20%的情况下进行单头拉拔和塞头拉拔是可能的;所获得的基础数据可以有效地用于实际生产。

The utilization of shape-memory alloy fine tubes in catheters and injection needles for medical tests and treatments is expected, since they do not react with organisms, and their torque transfer feature can be increased at the time of medical treatment and tests, facilitating easy clinical application, while reducing the patient's discomfort.In this study, using Ni-Ti shape memory alloys, we investigated the optimal drawing conditions for the sing and plug drawing of fine tubes, Ni-Ti alloys are excellent functional materials with ultra-elasticity and the characteristics of shape memory alloys; however, they are inferior with respect to ease of formability compared with practical alloys. Therefore, we conducted studies on the selection of an easy-to-draw lubricant, the optimization of drawing conditions including die angle and reduction of area, the clarification of drawing limits, the determination of shape-recovery percentages after drawing as well as after thermal treatment, and the determination of the inner- and outer-surface roughness of drawn fine tubes. We also discussed theoretically the distributions of stress and strain during drawing using a finite element method. Based on the results obtained, we clarified that sing and plug drawing with a reduction in the cross-sectional area of the fine tube of approximately 20% was possible; the basic data obtained could be effectively utilized in actual production.