发动机缸体双金属曲轴孔半精镗及精镗加工工艺

针对某发动机缸体曲轴孔的精加工精度要求,通过分析其加工难点,选择了镗削加工作为曲轴孔的精加工方法,并确定了刀具材料、加工冷却和排屑方式以及镗削时各项切削参数,制订了曲轴孔精加工时的定位和夹紧方案.通过机床实物制造,对工件进行了试切.经检测,曲轴孔各项精度指标均达到或超过设计要求,成功地在重庆某机械制造企业投产.     

用AutoLISP编程实现钻孔的自动绘制

煤矿的采掘工作主要以各种标准绘制的平面图为依据,这样,绘制标准的采掘工程平面图便成为煤矿安全生产的重中之重。     

某型镗铣床主轴系统结构设计

主轴系统是镗铣床的核心部件,合理地设计结构,能够提高主轴系统的刚性和切削性能,降低振动和噪声.通过对某型镗铣床主轴系统的设计阐述了镗铣类机床主轴系统设计的方法和原则,并以切削试验证明所设计的主轴系统具有良好性能.     

连杆应力曲线孔加工

针对连杆应力曲线孔的精加工,介绍一种专用数控连杆镗床和加工方法。     

Suppression of chatter vibration of boring tools using impact dampers

In this study, improvement of the damping capability of boring tools and suppression of chatter vibration were attempted using impact dampers. Bending tests, impact tests and cutting tests were carried out, whilst widely varying the method of applying an impact damper to a boring tool. The effects of the amount of free mass and clearance, the overhang length of boring tools and their cutting condition were investigated. As a result, the following points were clarified.

(i)

The damping capability of boring tools is considerably improved using impact dampers.

(ii)

All three types of impact dampers used in the experiment can considerably suppress the vibration of boring tools in the vertical direction (principal force direction), but hardly suppress it in the horizontal direction (thrust force direction) where the amplitude is extremely small.

(iii)

In practical use, the method of equipping an impact damper on the flank face of a boring tool is desirable.

(iv)

Using an impact damper, it is possible to bore deeper holes in comparison with boring tools now on the market and to improve the efficiency of boring operations.

Kinematic behaviour of a Tunnel Boring Machine in soft soil: Theory and observations

State-of-the-art shield tunnelling in difficult ground conditions still involves a trial-and-error approach as a complete understanding of the physics governing the interaction between the Tunnel Boring Machine (TBM)-shield and the surrounding soil is still lacking. This is particularly concerning as it was demonstrated that the shield–soil interaction, and especially the ground displacement around the shield periphery, gives a significant contribution to the overall soil deformation. This paper quantifies the radial soil displacements induced by a TBM-shield driving in soft ground. The displacements have been obtained by means of a model that captures several aspects of the kinematic behaviour of a TBM, based on theoretical and geometrical considerations. The theoretical model has been verified against TBM monitoring data obtained during the construction of the Hubertus Tunnel, a double-tube road tunnel located in The Hague, The Netherlands. Results show the amplitude and spatial distribution of the ground displacement around the shield periphery as they occurred in practice.     

汽车发动机铝锡曲轴瓦的高速金刚镗削试验研究

作者针对汽车发动机铝锡曲轴瓦的内圆加工，通过在试验装置上的一系列试验研究，探索在采用高速金刚镗削工艺条件下，切削用量与内圆表面粗糙度之间的关系，为该项工艺的生产应用提供了可靠的数据与理论依据。本文结论对铝合金件及其它有色金属件的机械加工也有普遍的实用意义。     

A novel magnetic actuator design for active damping of machining tools

Parts and cutting tools with large structural flexibility experience both forced and chatter vibrations during machining, resulting in poor surface finish or damage to the machine. This paper presents the design principles of a novel 3 degrees of freedom linear magnetic actuator which increases the damping and static stiffness of flexible structures during machining. The proposed actuator can deliver 248 N force in two radial (x, y) directions and 34 N×m (torque) in torsional (θ) direction up to 850 Hz. The force and torque reduces to 107 N and 14.5 N×m at 2000 Hz, hence it can actively damp a wide range of structural modes. The magnetic force is linearized with respect to the input current using magnetic configuration design strategy. Loop shaping controllers are designed for active damping of boring bar vibrations. The static and dynamic stiffnesses of the boring bar were considerably increased with the designed actuator, leading to a significant increase in chatter-free material removal rates during cutting tests.     

发动机缸体曲轴孔精加工专用夹具设计与研究

曲轴孔精加工工序的精度将直接影响发动机的寿命与品质,而先进合理的夹具系统是加工精度的重要保障。针对某企业对缸体曲轴孔精加工精度要求,确定了工艺参数及定位基准,在此基础上,对夹具系统的定位机构、让刀机构、夹紧机构及镗模等主要结构进行了设计与分析。最后,分析了镗杆的动态特性,并研究了轴承刚度对镗杆动态特性的影响,适当提高轴承预紧力即轴承刚度,能有效提高镗杆系统的刚度。经实际加工检验,验证了设计的正确性。     

贯流机组内、外配水环的同镗加工

针对贯流机组内、外配水环结构庞大、斜孔加工难度大的特点,采用同镗加工装置,对加工方法作了介绍。