\r杨志永，谢贤诗，李思远，姜 杉\r
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AuthorsHTML:\r杨志永，谢贤诗，李思远，姜 杉\r
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AuthorsListE:\rYang Zhiyong，Xie Xianshi，Li Siyuan，Jiang Shan\r
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AuthorsHTMLE:\rYang Zhiyong，Xie Xianshi，Li Siyuan，Jiang Shan\r
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Unit:\r天津大学机械工程学院，天津 300350\r
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Unit_EngLish:\rSchool of Mechanical Engineering，Tianjin University，Tianjin 300350，China\r
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Abstract_Chinese:\r本文旨在改善近距离后装式放射治疗机在使用过程中易出现的放射源卡源的问题，同时为了提高后装治疗机放射源的源到位精度，针对后装放射治疗机的关键治疗机构——源缆传送机构，进行了结构改进设计．首先，针对机构中的关键零部件绕丝轮的槽形进行了改进设计，经过对比分析，选用三角形槽的设计方案，并通过计算60°夹角的三角槽对源缆的摩擦驱动力，证明三角形槽能够提供足够的摩擦驱动力．基于以上所做出的改进，实现了源缆传送机构中片基带对源缆的完全包覆，保证了源缆在出丝和收丝的过程中不出现乱丝的问题；其次，对源缆传送机构的弹簧张紧力进行了设计与计算，通过摩擦传动受力模型计算出张紧弹簧的最小张紧力值，确定了片基带与绕丝轮之间不出现滑移的条件；再次，设计了一种浮动导向管用于辅助源缆的出丝、收丝过程，分析了浮动导向管对提高源到位精度的影响；最后，基于电磁定位仪、光纤传感器以及直线导轨等元器件，创新搭建验证改进结果的实验平台，通过设置使用不同的弹簧张紧力、绕丝轮槽形以及浮动导向管的实验组别，进行对照实验．实验得到的数据显示，改进后的后装治疗机的源到位精度得到了提升，其精度为≤±0.6 mm，同时，后装治疗机出丝、收丝过程中的卡源现象显著减少．\r
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Abstract_English:\rThe goals of this paper are to mitigate the situation involving the radioactive source being attached to an undesired location during the operation of an afterloader and to increase the source-to-position accuracy of the radioactive source. An improved structural design was developed for the source-cable transmission mechanism，which is the key treatment mechanism of the afterloader. First，the design of the groove shape of the reel，which is the key component of this mechanism，was improved. In this paper，after performing a comparative analysis，the design scheme of the triangular groove was selected，and the friction driving force of the source cable was calculated based on a triangular groove angle of 60°；this result proved that the triangular groove can provide sufficient friction driving force. To prevent the source cable from appearing disordered during the process of cable feeding or winding，it was completely wrapped in the tension belt based on the aforementioned improvement measures. Second，the spring tension of the source-cable transmission mechanism was designed and calculated. The minimum tension value of the tension spring was calculated using the friction transmission force model；for the conditions determined by the model，no slip was found to exist between the tension belt and the reel. Third，a floating guide tube was designed to assist in feeding or withdrawing the cable，and the influence of the floating guide tube on improving the source-to-position accuracy was analyzed. Finally，based on components such as the electromagnetic locator，the fiber optic sensor，and the linear guide rail，an innovative experimental platform was set up for improved verification of results. The control experiments were performed by setting up experimental groups using different values of spring tension，different grooved reels，and different floating guide tubes. The experimental data show that the source-to-position
accuracy of the afterloader has been improved to be ≤±0.6 mm. Moreover，the occurrences of the source being attached to an undesired location are significantly reduced when the cable feeds or withdraws.\r
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Keyword_Chinese:后装治疗机；源到位精度；源缆传送机构；绕丝轮\r

Keywords_English:afterloader；source-to-position accuracy；source cable transmission mechanism；source reel\r


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