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注射成形高强钛合金复杂零件的尺寸精度控制

Dimensional accuracy control for complex components of high-strength titanium alloys by metal injection molding

  • 摘要: 采用注射成形技术制备出高强钛合金小尺寸复杂形状铰链零件,利用光学影像测量仪和三维影像仪测试了零件在不同工艺下的尺寸数据,分析了蜡基和塑基粘结剂体系、脱脂工艺、摆放方式和整形工艺对零件尺寸及形状的影响规律。结果表明:相对于蜡基粘结剂注射坯,塑基注射坯的强度高,在脱脂过程中不易变形,其烧结态零件的尺寸稳定性更高。在脱脂阶段,蜡基注射坯会产生“溶胀”现象,导致其尺寸精度较塑基注射坯更低;在烧结阶段,通过调整零件摆放方式以及承烧板粗糙度等辅助方法进一步控制坯体的变形和尺寸精度。经烧结工装辅助支撑以及零件冷整形处理后,注射成形高强钛合金零件的尺寸精度可达到±0.1%。

     

    Abstract: High-strength titanium alloy hinge components with complex geometry were fabricated by metal injection molding (MIM). The dimensional characteristics of these components were systematically evaluated under various processing conditions by optical and three-dimensional imaging instruments. The influences of degreasing methods, part orientation, molding techniques, and binder systems (specifically plastic-based and wax-based binders) on the dimensional accuracy and shape stability of the components were investigated. The results show that, compared with the wax-based injection green parts, the plastic-based injection green parts have the higher strength, which are less prone to deformation during debinding, and exhibit the higher dimensional stability of the sintered parts. During the debinding stage, the wax-based injection green parts could produce a “swelling” phenomenon, resulting in lower dimensional accuracy than that of plastic-based injection green parts. During the sintering stage, the dimensional precision can be further enhanced by optimizing part orientation and adjusting the surface roughness of sintering plates. Ultimately, through the sintering fixtures and post-molding reshaping treatments, the dimensional accuracy of MIM-fabricated titanium alloy components can be controlled within ±0.1%.

     

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