铸态高铝锌基合金（ZA27）电梯曳引机蜗轮材料安全可靠性研究

发布时间：2018-01-17 13:26

本文关键词：铸态高铝锌基合金（ZA27）电梯曳引机蜗轮材料安全可靠性研究　出处：《深圳大学》2016年硕士论文　论文类型：学位论文

【摘要】：近年来,随着材料工艺技术发展,国内电梯行业开始采用具有生产工艺简单、性能优良、低成本等优点的铸态高铝锌基合金ZA27制作曳引机蜗轮。然而目前,国内外专家学者对铸态高铝锌基合金ZA27的研究集中在改善材料综合机械性能,对其作为电梯曳引机蜗轮材料方面的系统研究依然空白,尚未对其作为电梯曳引机蜗轮材料进行安全可靠性评估,也未制定出相关技术指标。随着电梯增多,由铸态高铝锌基合金ZA27曳引机蜗轮失效引起的安全事故也随之增多,人们对铸态高铝锌基合金ZA27能否用于电梯曳引机蜗轮提出质疑。因此,对铸态高铝锌基合金ZA27电梯曳引机蜗轮材料安全可靠性研究具有重要意义。对出现断齿现象的电梯曳引机蜗轮进行失效分析。结果表明,蜗轮材料的主成分含量符合GB/T1175-1997《铸造锌合金》中的牌号成分含量。轮齿断裂是疲劳断裂,断裂源在齿根部位。首损齿齿根处存在疏松、气孔、夹杂等铸造缺陷,局部疏松相连形成缺陷聚集区。这些缺陷的存在引起局部应力集中,降低材料抗拉强度,裂纹在缺陷处萌生并向四周扩展。在交变载荷作用下,裂纹不断扩展,最后轮齿发生折断;断齿表面有剥落点蚀坑存在,经验证,轮齿齿面点蚀出现几率与其组织中铸造缺陷分布与大小有关。对不同铸造工艺制造的高铝锌基合金ZA27电梯曳引机蜗轮毛坯组织性能进行表征,并与铸造锡青铜的性能对比,全面分析影响铸态高铝锌基合金ZA27电梯曳引机蜗轮正常使用因素。结果表明,最佳铸造工艺为挤压铸造,该工艺下的蜗轮显微组织致密,晶粒形貌为细小等轴晶;关键部位无缩孔、疏松和夹杂物等铸造缺陷存在;抗拉强度为412MPa,断后伸长率为6.5%,冲击功为53.5J,显微硬度为127.9HV,摩擦系数为0.101~0.118。并且其力学性能优于铸造锡青铜。利用有限元分析,建立铸态高铝锌基合金ZA27电梯曳引机蜗轮力学数学模型,计算在极限工况下蜗轮所受应力,分析有限元计算结果。结果表明,最大应力发生在齿根区域;当轿厢负载125%额定载荷且静止或轿厢负载110%额定载荷以加速度9.8m/s2在底层启动或轿厢负载125%额定载荷以加速度9.8m/s2在底层紧急制动等三种极限工况下,曳引机均不会发生失效。因此控制好蜗轮关键部位铸造缺陷程度及蜗轮工作温度情况下,铸态高铝锌基合金ZA27则能够安全用于电梯曳引机蜗轮的制造。
[Abstract]:In recent years, with the development of material technology, domestic elevator industry began to adopt simple production process and excellent performance. The wormgear of traction machine is made by ZA27 with low cost and so on. However, at present, domestic and foreign experts and scholars focus on improving the comprehensive mechanical properties of as-cast high Al-Zn base alloy ZA27. The systematic research on the material of worm wheel of elevator traction machine is still blank, and the safety and reliability of the material of worm wheel of elevator traction machine has not been evaluated, and the related technical index has not been worked out. With the increase of elevator. The safety accidents caused by the failure of the wormgear of the cast high Al-Zn base alloy ZA27 traction machine are also increasing. People question whether the as-cast high aluminum-zinc base alloy ZA27 can be used in the worm wheel of the elevator traction machine. It is of great significance to study the material safety and reliability of wormgear of ZA27 elevator traction machine with high Al-Zn-base alloy. The failure analysis of worm wheel of elevator traction machine with broken tooth is carried out. The principal component content of worm gear material is in line with the grade composition content in GB/T1175-1997 cast zinc alloy. The gear tooth fracture is fatigue fracture. The fracture source lies in the root of the tooth. There are some casting defects such as porosity, porosity, inclusions and so on in the root of the first loss teeth, which are loosely connected to form the defect accumulation area. These defects cause the local stress concentration and reduce the tensile strength of the material. The crack germinates at the defect and propagates all around. Under the action of alternating load, the crack continues to grow, and the last gear tooth breaks. There are denudation pits on the surface of broken teeth, which have been verified. The occurrence probability of pitting corrosion of gear tooth surface is related to the distribution and size of casting defects in its structure. The microstructure and properties of worm wheel blank of high aluminum zinc base alloy ZA27 elevator traction machine manufactured by different casting processes are characterized. Compared with the properties of cast tin bronze, the factors affecting the normal use of wormwheel of ZA27 elevator traction machine with high Al-Zn base alloy were analyzed. The results showed that the best casting technology was squeeze casting. The microstructure of the worm wheel is compact and the grain morphology is fine equiaxed crystal. There are no shrinkage holes, loose and inclusions and other casting defects in key parts. The tensile strength is 412MPa, the elongation after break is 6.5, the impact energy is 53.5J, the microhardness is 127.9 HV. The friction coefficient is 0.101 and 0.118, and its mechanical properties are better than that of cast tin bronze. Based on the finite element analysis, a mathematical model of wormwheel of ZA27 elevator traction machine with high Al-Zn base alloy is established. The results of finite element analysis show that the maximum stress occurs in the tooth root region. When the car load is 125% rated and the static or car load is 110% rated at an acceleration of 9.8 m / s ~ (2) at the bottom or 125% rating at the bottom of the car load at 9.8 m / s ~ (2). First floor emergency braking and other three limit conditions. Therefore, under the condition of controlling the casting defect degree of the key parts of the worm gear and the working temperature of the worm gear, the as-cast high Al-Zn base alloy ZA27 can be safely used in the manufacture of the worm wheel of the elevator traction machine.
【学位授予单位】：深圳大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TU857;TG146.13

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