超高速铣削及其在高硬度钢加工中的应用

阐述了高硬度钢超高速铣削的特点和应用,并讨论了其刀具系统、切削工艺参数和铣削方式等主要相关技术。     

淬硬钢高速切削加工技术研究

淬硬钢高速铣削加工具有传统加工无可比拟的优势,是淬硬钢加工的发展方向.从切削刀柄和刀具、加工工艺、数控编程等方面阐述了淬硬模具钢高速加工的技术特点.     

高速干切削加工技术

作为一种新型的绿色制造技术，高速干切削技术对实施人类可持续发展战略有重要的意义.阐述高速干切削加工及其关键技术（包括刀具技术、机床技术和工艺技术等）。     

沟槽高速切削技术及其加工策略研究

目前在机械加工领域,沟槽广泛出现在精密设备的关键件上,由于沟槽是由高精度的异形槽构成,因此采用传统加工工艺难度很大,加工成本过高。这里将高速切削技术应用到沟槽类零件的加工中,提出了零件的工装设计与装夹方案。并对高速切削过程中涉及的粗加工、半精加工和精加工策略进行探讨,最后总结出加工中缓解刀具寿命下降的工艺措施。     

高锰钢切削刀具的设计

高锰钢切削极易产生硬化层,很难加工。在生产实践中,通过合理地选择刀具材料、刀具结构、切削用量等,可以很好解决高锰钢难加工的问题,保证了高锰钢的加工质量。     

Wear behaviors of single-layer and multi-layer coated carbide inserts in high speed machining of hardened AISI 4340 steel

Flank wear progression and wear mechanisms of uncoated, coated with PVD applied single-layer TiAlN, and CVD applied multi-layer MT-TiCN/Al₂O₃/TiN cemented carbide inserts were analyzed during dry turning of hardened AISI 4340 steel (35 HRC). Experimental observations indicate that by applying a coating to the uncoated insert the limiting cutting speed increase from 62 to 200 m/min, which further extends up-to 300–350 m/min when using multi-layer coating scheme. Relatively lower wear rate seen when using single-layer TiAlN coated inserts. However, after removal of the thin layer of coating the wear rate increase rapidly, subsequently dominates the wear rate of multi-layer coated inserts. Cutting forces; especially axial and radial components have also shown the similar behavior and increase rapidly when the tool failure occurs. Flank wear, crater wear and catastrophic failure are the dominant forms of tool wear. Digital microscope and SEM images coupled with elemental analysis (EDAX) have been taken at various stages of tool life for understanding the wear mechanisms.     

高速切削加工中切削力的应用研究

通过采用一种新型的试验装置,可重现在了较大的切削速度范围内(从15～100m/s),正交切削下的切削过程.该试验设备可以记录在正交切削下的切削过程中法线方向上和切线方向上的作用力数值.从而在很大的切削速度范围内,可以对刀具和切屑之间的摩擦力进行分析.给出了切削力的分力变化和摩擦系数变化的情况.此外,通过可以使用一台高速摄影机,记录了高速加工中,切屑的形成过程的图像.     

Surface topography analysis in high speed finish milling inclined hardened steel

The surface texture of a milled surface is an inherently important process response in finish milling. It is one of the most commonly used criteria to determine the machinability of a particular workpiece material. However, literature survey on the study of the surface topography analysis relating to the cutter path orientations when high speed finish inclined milling is scant. Previous works were either involved in conventional milling of easy-to-cut workpiece materials or machining at different workpiece inclination angles. Furthermore, none of the previous work has detailed the true surface topography of the machined surface with regards to the cutter condition. Instead, the works provided quantitative values in terms of the Ra value. This article is concerned with evaluating cutter path orientations on an inclined workpiece angle of 75° to simulate finish milling of free form moulds and dies. Surface topography effects are assessed with regards to different cutter path orientations on its surface. The aims of this study are to provide an in-depth understanding on the surface texture produced by various cutter path orientations when high speed finish inclined milling hardened steel at a workpiece inclination angle of 75° using surface topography analysis and determine the best cutter path orientation with respect to the best surface texture achieved. 3D topography maps together with 2D surface profiles are used to assess the experimental results. The conclusion is that milling in a single direction vertical upward orientation gave the best workpiece surface texture.     

现代刀具材料系列讲座（三）：涂层高速钢刀具

介绍了涂层高速钢刀具的切削性能,并列出了涂层与未涂层高速钢刀具的对比切削数据。     

高硬度淬硬钢高速铣削过程的切削温度研究

通过设计在不同加工工艺参数条件下高速铣削高硬度(48HRC～ 68HRC)淬硬钢试验,研究了切削温度信号的特征,分析了切削温度与淬硬钢材料硬度、切削工艺参数的关系.结果 表明:随着淬硬钢材料硬度的增大,切削温度呈现递增趋势,4种淬硬钢的切削温度随材料硬度变化顺序为:PM60＞SKD11＞S136＞P20,其中,PM60...     

淬硬钢的高速、高精度硬切削

聚晶立方氧化硼(PCBN)刀具代替磨削刀具使用于硬加工,但是由于加工过程中安全性的缺点到目前尚不能用于淬硬钢的高速和高精度加工。现在新开发的刀刃材料和变化的进给速度新工艺使这类刀具的应用成为可能。     

Assessment of white layer in hardened AISI 52100 steel and its prediction using grinding power

In the present work, the effect of various grinding mechanisms on white layer (WL) formation in AISI 52100 steel is studied using two types of alumina grains, one produced by sol–gel process and the other by conventional fusion. Further, a novel approach is proposed on predicting the WL formation using grinding power. This study correlates the power variation with the change in the metallurgical aspects of the work material. WL of about 56 µm thickness is observed in the material ground by worn out sol–gel alumina wheel. However, no WL is present in the material ground by fused alumina wheel. High toughness in sol–gel alumina led to generation of wear flats with increasing grinding passes and transformed the dominant grinding mechanism from shearing to plowing and sliding. This increases the temperature in the grinding zone, which was the reason for WL formation. Change in the dominant grinding mechanisms from shearing is found to increase the grinding power. Since the change in dominant grinding mechanisms is the cause for WL formation, the increase in grinding power is found to be a good measure in predicting the WL formation. The predictability of WL formation by grinding power is further validated by comparing the power variation in grinding process by both the grinding wheels.     

高硬度材料的超高速铣削

阐述高硬度材料超高速铣削技术的优点和应用,并重点讨论了其刀具系统和切削工艺参数等关键技术。     

高速切削技术的发展与展望

结合国内外高速切削技术的研究现状,介绍高速切削的概念、国内外发展动态及其相关技术的发展;探讨高速切削的应用领域;分析高速切削研究现存问题并展望高速切削的发展趋势和未来研究方向。     

PCBN刀具断续切削淬硬钢瞬态冲击力研究

基于正交试验设计方法,使用PCBN刀具进行干式断续车削淬硬钢Cr12Mo V试验,研究了不同切削参数与工件硬度对瞬态冲击力的影响。应用响应曲面法建立了瞬态冲击力的线性预测模型和指数预测模型。研究结果表明:断续切削方式下,工件硬度和切削速度对瞬态冲击力有显著影响;线性预测模型和指数预测模型均能准确地对瞬态冲击力进行预测。     

Tribological properties of hardened high strength Boron steel at combined rolling and sliding condition

The use of hardened high strength steel is found in applications where high wear resistance is required. The wear properties of high strength Boron steel are well known in applications with abrasive wear from stones, ore and other hard material. A unique concept of wear protection of rails is newly presented, a wear resistant cap made of hardened high strength Boron steel.Reducing the wear of rails and wheels and controlling the frictional behavior in the wheel/rail contact are two key issues for railway owners in order to reduce the increasing costs related to higher axle loads, higher speeds, more frequent traffic, etc. Therefore, the aim of this work has been to investigate and compare the tribological properties of Boron steel and UIC 1100 rail steel in contact with Blue Light wheel steel (AAR Class C (69-JDG-8)) under dry and water lubricated conditions in a two-disc tribometer. Advanced analytical instruments including 3D optical surface profiler, micro-hardness indenter, light microscope and SEM/EDS were used to analyze the results.Results from the experiments show that the friction coefficient in tests with Boron steel is more stable both in dry and water lubricated conditions than tests including UIC 1100 rail steel used in todays application. Surface damages seen from water lubricated tests on UIC 1100 rail steel are not seen on the surface of the Boron steel discs. In all tests, the wear decreased when water was added in the contact and friction was slightly decreased.     

45钢高速切削过程中切屑形成的数值模拟

为了研究45钢高速加工中切屑形成机理,建立了高速加工的正交切削有限元模型,研究了45钢高速切削有限元建模过程中的Johnson-Cooks材料模型,刀屑接触模型及切屑分离准则等关键技术.利用建立的有限元模型对45钢的高速切削过程中的切屑成形进行了数值模拟,并研究了不同切削速度对切屑锯齿化程度的影响规律,得到了不同切削速度下的切屑锯齿化程度.     

Effect of different heat treatments on the wear of high speed steel cutting tools

High speed steel tool tips were given different heat treatments to vary the microstructure, and the nature of the wear produced in turning tests was examined under the scanning electron microscope. Wear was mainly confined to either the rake face or clearance face, the form of wear being dependent on the particular heat treatment of the tool steel. The forms and mechanisms of tool wear are discussed in terms of the changes in microstructure produced by the different heat treatments.     

Influence of magnetorheological elastomer on tool vibration and cutting performance during boring of hardened AISI4340 steel

During boring process, tool vibration is a major concern due to its overhanging length, which results in high cutting force, poor surface finish, and increase in tool wear. To suppress tool vibration and improve cutting performance, a novel technique in rheological fluid was designed and developed. In this work, a magnetorheological elastomer (MRE) was developed, and parameters, such as piston location, current intensity, and coil winding direction, were considered. Cutting experiments were conducted to obtain a set of parameters that can efficiently control vibration during boring of hardened AISI 4340 steel. Taguchi method was used to optimize the cutting condition, and findings show that the cutting tool embedded with the MRE reduced tool vibration and effectively increased cutting performance.

     

Influence of cut layer on cutting

The contact of the chip with the tool’s front surface in cutting is analyzed by numerical modeling. The high-pressure zones and buildup at the tool’s contact surface are studied. The influence of plastic instability of the chip surface and vortex deformation modes on tool wear is considered.