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凿岩机活塞是一个典型承受多次冲击载荷的零件,目前失效主要方式为崩齿,折断和端面下凹。本文首先重点讨论了高碳钒钢之所以能用作此类零件的关键在于整体淬火薄层硬化(即国外所谓薄壳淬火),指出淬硬层深度及其分布和相应内应力大小及其分布在活塞抗崩齿和折断失效中所起的重大作用。和崩齿、折断作斗争中,为改善淬硬层强韧性以提高材料的多冲抗力。在淬火问题上研究了盐浴短时加热新工艺,以期在高碳淬硬层中能获致部分板条状马氏体;在回火问题上。分析了正断、切断抗力随回火过程变异规律。作出适当提高回火温度的决定;在锻造问题上研究了加热过程中“组织遗传性”的影响,提出了锻造加热温度的下限。此外,根据承受多次冲击零件的应力集中问题,体积均一性问题,冲击配偶件的配合硬度问题等对活塞的合理结构设计,正确加工工艺,钎尾几何形状和配合硬度等各方面提出了相应的改进措施和规定。和端面下凹作斗争中,除采用上述改进淬硬层强韧性的各项措施外,重点研究了未熔碳化物在冲击接触疲劳中的作用。指出,为减少端面下凹,活塞应具有小、少、匀、圆的未熔碳化物,而为获得小、少、匀、圆的未熔碳化物,研究和提出了预先托氏体化处理,然后亚临界点加热等温球化的新工艺。三年来,在上述试验研究基础上,试验活塞的平均寿命从500米提高到4600米,超过了实测的日本同类产品的寿命水平。批量生产的活塞使用寿命也达到了原有水平的六倍。
Rock drill piston is a typical load to withstand multiple impact parts, the main failure of the current main method is broken teeth, broken and face concave. The key point of this paper is to discuss the reason why high-carbon vanadium steel can be used as such parts is the hardening of the whole hardened thin layer (ie the so-called thin shell quenching abroad), pointed out the hardened layer depth and its distribution and the corresponding internal stress size and distribution Piston in the anti-collapse and fracture failure played a significant role. And collapse teeth, broken fight, to improve the toughness of the hardened layer to improve the material multi-impact resistance. In the quenching problem, the salt bath short-time heating new technology was studied in order to obtain some lath martensite in the high-carbon hardened layer; on the tempering problem. The regularity of breaking resistance and the variation of cutting resistance with the tempering process were analyzed. Make the appropriate decision to raise the tempering temperature; study the influence of “heredity” on the forging process and put forward the lower limit of the forging heating temperature. In addition, based on the stress concentration problem, the uniformity of volume, the matching hardness of the impact partner, etc., the reasonable structural design, the correct machining technology, the geometry of the shank and the hardness of the shank are put forward according to the aspects of stress concentration, Improvement measures and regulations. In addition to adopting the above measures to improve the strength and toughness of the hardened layer in the fight against the sagging of the end face, the role of the unmelted carbide in the impact contact fatigue has been mainly studied. It is pointed out that the piston should have small, small, uniform and round unmelted carbides in order to reduce the concave of the end face. In order to obtain small, small, uniform and round unmelted carbides, , Then subcritical heating isothermal ball of the new technology. In the past three years, based on the above experimental studies, the average life of the test piston was raised from 500 to 4,600 meters, which exceeded the life expectancy of similar Japanese products. Piston mass production of life has reached six times the original level.