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摘要: 多孔金刚石磨具是一种能在磨削加工过程中提供容屑和冷却液流通空间的新型工具。以激光选区熔化成形为代表的增材制造技术,是制造多孔金刚石工具的有效手段。然而,受激光增材制造的光斑尺寸约束、逐层成形等技术特征影响,所设计的多孔金刚石工具难以精准成形,因此有必要对微结构的可成形性进行研究。本文以CuSn20/金刚石复合材料为研究对象,采用激光选区熔化技术成形了不同成形方向、不同尺寸的悬垂结构、薄壁、圆孔和尖角等微结构,并对其可成形性、成形误差及产生原因进行分析。结果表明:悬垂结构的最佳可成形长度为1~2 mm;薄壁结构的最小可成形尺寸为0.70 mm;垂直于成形方向的圆孔结构的最小可成形直径尺寸为0.20 mm;平行于成形方向的圆孔结构的最佳成形直径尺寸为0.50~3.00 mm;尖角结构的可成形角度需大于10°。微结构的成形误差主要受激光对复合粉末的热吸附、激光光斑热影响区扩散以及复合粉末的弱支撑等作用影响。本文的研究结果为复杂金刚石工具的设计及增材制造提供了一定的技术参考。
关键词 激光选区熔化; 金刚石复合材料; 特征微结构; 工艺约束
中图分类号 TG74; TG66Abstract: Porous diamond grinding tools are a new-type tools that can provide a space for chip holding and coolant flowing during the grinding process. Selective Laser Melting (SLM), as a typical additive manufacturing technology, is an effective method to fabricated porous diamond tools. However, due to the limitations of spot size and layer by layer fabricating process in SLM process, the designed porous diamond tools are difficult to be manufactured accurately. Therefore, it is necessary to investigate the manufacturing process constraint of feature structures. Based on CuSn20/diamond composites, a series of feature structures such as overhang structures, thin-walled, holes, and sharp angle structures with different fabricating directions and sizes were fabricated by SLM technology. The formability, forming errors, and causes of these structures are analyzed. The results show that the optimal formable length of the overhang structure is 1-2 mm; The minimum formable size of thin wall structures is 0.70 mm; The minimum formable diameter size of hole structures perpendicular to the fabricating direction is 0.20 mm; The optimal forming diameter size for circular hole structures parallel to the fabricating direction is 0.50-3.00 mm; The formable angle of sharp angle structures should be greater than 10 °. The forming error of feature structures is mainly affected by the thermal adsorption of laser on composite powder, the diffusion of laser spot heat affected zone, and the weak support of composite powder. This work provide a certain technical reference for the design and additive manufacturing of complex diamond tools.
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