Effect of Ti content on the microstructure and mechanical properties of laser clad Ti/B4C/dr40-based composite coatings on shaft parts surface

As a transmission part, the service life of the shaft parts directly affects the machining efficiency and economic benefit, and requires higher surface hardness and wear resistance. In this study, the Ti/B₄C/dr40 composite powder was cladded on the shaft part surface via laser cladding to improve the microhardness and wear resistance. The microstructure evolution and phase structure were analyzed to reveal the strengthening mechanism of Ti and B₄C on dr40 coating. The Ti/B₄C/dr40 composite coating with low defects and good interface metallurgical bonding quality between coating and substrate was prepared on the 45# steel shaft part. The results show that the main phase in the Ti/B₄C/dr40 composite coating is TiC, TiB₂, Cr₂C₃, (Ti, Cr) C, (Ti, Cr, Fe, Ni) (C, B). With the addition content of Ti increasing, the grain densifies, the sieve-reticular structure and small strip phase at grain boundary and intergranular area change as massive phase. Moreover, the microhardness improves up to 2.05 times than that of dr40 coating. The in-situ synthesis of carbides and borides are evenly distributed in the coating, which improves the deformation resistance of the coating. In addition, the precipitation and solid solution strengthening caused by reinforcement phase also enhanced matrix strength for supporting reinforcement phases, improving the coating wear resistance.     

角接触球轴承对高速主轴变形影响建模与分析

高速主轴在工作过程中易受热变形影响数控机床加工精度,而角接触球轴承作为高速主轴的支承件发挥着巨大的作用。根据Hertz接触力理论,结合角接触球轴承受力平衡以及位移方程,建立角接触球轴承对主轴位移影响的分析模型,然后通过对比用模型计算的轴套位移值与用位移传感器测得的轴套位移值来进行验证;最后分析计算不同转速下轴承内外圈接触力和轴承刚度的影响,以及不同转速下对轴套和主轴位移产生的影响。利用该模型可以设置合理的预紧载荷以及主轴转速,提高轴系的运动定位精度,为轴承预紧量的施加、工作预紧载荷的调整及预紧装置的设计提供参考,弱化轴承塑性变形导致的热变形,从而降低对高速主轴变形位移产生的影响。     

电磁屏蔽暗室门的合页分析及优化

普通的隔音电磁屏蔽门自重和关门阻力较大，合页易变形和损坏，导致隔音屏蔽性能不理想。为了解决这一问题，以屏蔽门、合页和合页轴为研究对象，对其进行三维建模和有限元分析，得到部件的应力、位移及安全系数的分布规律。通过对数据及图形参数的分析，进行结构的设计和优化，加强了合页、合页轴的强度。合页轴的强度对于门扇应用的影响尤为关键。     

解决氮压机轴振动不正常的特殊启动法

4MSGEP7/15型氮压机因为润滑油温度低而启动成功率低,根据环境温度,采取不同的润滑油加热方法,提高了氮压机润滑油的温度,使氮压机的轴振动值达标,启动成功率达到100%。介绍氮压机轴振动值大的原因分析过程和优化操作的具体实施方案。     

Excavation cycle times recorded during sinking of a deep shaft in crystalline rock – A case example at Ventilation Shaft of Mizunami URL,Japan

Realistic and properly planned excavation cycle times developed prior to tunnel construction are an important issue for dependable project management, including cost estimation and time saving. Existing design studies, conducted to estimate the total cost for geological disposal, have been limited to estimates of approximate construction total time schedules. There were no case studies which compared the detailed excavation cycle time used in design studies with the actual results from an excavation taking into account each excavation cycle operation and task. In this paper, analyses of actual cycle time recorded during the sinking of the Ventilation Shaft of the Mizunami Underground Research Laboratory and comparison with the planned cycle time developed in the design stage are intended for an evaluation of the baseline work plan and schedule and for optimization of the calculations for application to shaft construction in any future repository in Japan. Actual times to perform three operations, drill and blast, muck removal and concrete lining emplacement were much larger than expected and represent the largest portion of the total excavation cycle time and had the largest impact on the efficiency of the excavation cycles and schedules. Operating at increasingly greater depths and excavating harder, more competent rock combined to significantly affect the shaft sinking speed. The underlying reasons for increases in actual times for the excavation cycle operations compared to their design estimates fall into three categories: constraints on construction; to ensure safety; and maintenance.     

60000m~3/h空分设备空压机轴振动值高的故障诊断

由于60000 m3/h空分设备空压机排气侧轴承预紧力过大以及增速机与压缩机接触间隙过小,导致空压机吸气侧及增速机轴振动值高。文章介绍了空压机的结构、主要技术参数,叙述了空压机轴振动值高的故障现象,阐述了处理措施及效果。     

陀螺两井定向技术在郭屯千米深井井筒安装中的应用

该文介绍了陀螺两井定向技术在井筒安装中的运用,并以菏泽鲁能煤电有限公司郭屯煤矿近千米立井安装施工为例,论述了利用陀螺两井定向结果快速、准确的在大深度立井井筒安装中的技术应用,对于深井安装,具有较强的实践性和推广意义。     

用于甲乙酮装置上的变频电机故障分析及处理

用于甲乙酮装置上的变频电机因前轴承温度高而造成停车故障.应用PeakVue技术对变频电机的运行状况进行了分析,提出了排除故障的措施.     

压力机高速轴镦粗过程组织转变的数值模拟

通过有限元方法模拟了压力机高速轴毛坯的镦粗过程,得到了镦粗过程的变形规律,模拟过程符合理论分析的结果;进而模拟了镦粗过程中微观组织的变化,得到了晶粒生长规律和位错密度变化情况,从微观上揭示了锻造过程的成形规律.