Research on Austempered Ductile Iron Gear

本研究旨在研究等温淬火球墨铸铁(ADI)的强度和加工性能，为其在齿轮上的应用奠定基础。开发新的ADI；通过对新ADI的金属组织和机械性能的研究，开发出具有足够的强度和优异的齿轮材料加工性的ADI，即机械性能为抗拉强度100 Kgf/mm^2，弹性10%，布氏硬度300，石墨颗粒数约为250/mm^2.2。可加工性试验：(1)滚刀试验，采用15ﾟ卸荷角和5ﾟ前倾角的滚刀和/或用压缩空气冷却滚刀齿对提高滚刀寿命是有效的。用金属陶瓷精滚刀精加工的ADI齿轮的齿形精度为JIS 0级，齿面粗糙度Rmax为2-3微米。在使用飞刀的基本测试中，这种ADI能够以100米/分钟的切割速度被切割。(2)滚齿圆角；m…较详细地研究了滚压圆角的方法和条件。轧制后的ADI齿轮表面硬度升高，对齿轮的弯曲疲劳强度有较大影响。承载能力；(1)弯曲强度；在用脉动器进行的弯曲疲劳试验中，HEW ADI的弯曲强度对于齿轮材料是足够的。经喷丸处理后的ADI齿轮的弯曲强度接近。渗碳钢齿轮的。(2)齿面耐久性；用双滚柱式疲劳试验机进行滚子试验表明，ADI齿轮表面硬度的提高有助于提高表面耐久性，而石墨颗粒的数量与ADI齿轮的表面损伤有关。齿轮试验表明，滚齿的ADI齿轮具有足够的表面耐久性，并且用金属陶瓷滚刀加工ADI齿轮可以提高耐久性。结论：在制造方面，通过优化刀具材料和刀具几何形状以及切削条件，可以有效地制造新型ADI齿轮材料。在材料强度方面，ADI在中等硬度齿轮区域具有足够的强度。金属陶瓷精滚刀对齿面粗糙度的改善，以及滚压和喷丸对齿圆角的加工硬化，表明ADI齿轮有可能应用于高硬度齿轮，如渗碳或感应淬火齿轮。较少

This research aims at investigation of the strength and the machinability of austempered ductile iron (ADI) for its application to gears.1. Development of the new ADI ; By investigating the metallic structures and the mechanical properties of new ADI, the ADI that has enough strength and superior machinability for gear material is developed, that is, the mechanical properties are 100Kgf/mm^2 in tensile strength, 10% in eloggation, 300 in Brinell hardness and the number of graphite grains is approximately 250/mm^2.2. Machinability tests ; (1) Hobbing tests ; The hob with relief angle of 15ﾟ and rake angle of 5ﾟ and/or the cooling of the hob teeth by the compressed air are effective in the improvement of hob life. The ADI gears finished with a cermet finishing hob result in JIS class 0 in tooth profile accuracy and Rmax 2-3mum in tooth surface roughness. In fundamental tests using a fly-tool, this ADI is able to be cut at cutting speed of 100m/min. (2) Rolling of the tooth fillet ; The m … More ethod and the conditions of the rolling of the tooth fillet are investigated in detail. The rise of the surface hardness of the ADI gear rolled is shown, which has a great influence on the bending fatigue strength of gear teeth.3. Load-carrying capacity ; (1) Bending strength ; In bending fatigue tests with a pulsator, the bending strength of the hew ADI is sufficient for the gear material. The bending strength of the ADI gear after shot-seening treatment is nearly equal to. that of the carburized steel gear. (2) Tooth surface durability ; Roller tests using a 2-roller-type fatigue tester clarifieds that the increase of the surface hardness of the ADI gear contributes to improvement of the surface durability, and that the number of graphite grains relates to the surface damage of the ADI gear. Gear tests represents that the ADI gears hobbed have sufficient surface durability, and that the durability increases by finishing the ADI gear with the cermet hob.4. Conclusions ; The new ADI concerned is possible to be manufactured as a gear material efficiently by the optimization of tool materials and tool geometries and the cutting conditions in manufacturing aspects. The ADI has sufficient strength in the region of medium hardness gears in aspects of the material strength. The Improvement of the tooth surface roughness with the cermet finishing hob and the work-hardening of the tooth fillet by the rolling and the shot-seening represent the possibility of application of the ADI gear to the region of high hardness gears such as case-carburized or inductionhardened gears. Less