Wear mechanisms of the rough form tools in the automatic screw machine test

Tool wear mechanisms of the rough form tools in the automatic screw machine test during machining of bismuth-bearing low carbon resulfurized free machining steel under practical machining conditions were investigated. Four mechanisms, namely mild adhesive wear, abrasive wear, continuous wear, and plastic deformation have been observed to play some roles simultaneously. Mild adhesive wear, which is a wear process taking place during detachment of an adhered chip, is believed to be enhanced by fatigue. Abrasive wear could take place either by oxide inclusions in the workpiece or by the primary carbide particles of the tool freed by some wear mechanisms. Continuous wear has been attributed to some type of atomic process, most probably dissolution of tool material into the chip. On the flank face, continuous, abrasive, and mild adhesive wear are believed to be the major wear mechanisms. On the rake face, continuous wear appears to be the predominant tool wear mechanism. Based on this investigation and consideration of the effect of built-up edge (BUE), reduction of cutting force, optimization of BUE size, stabilization of BUE, and reduction of oxide inclusions are found to be important for reduction of tool wear under practical machining conditions.     

数控机床进给滚珠丝杠的选择与计算

本文论述了数控机床进给用滚珠丝杠的选择与计算方法 。     

液压马达最低稳定转速分析及实验研究(上)

本文阐述了液压马达最低稳定转速的含义、评判标准及其影响决定因素。提出了基于静态调速方程的解析分析方法，并推导了阀控马达液压系统最低稳定转速的失速方程。研究设计了静负载扭矩的液压加载装置。     

Friction in feed drives of machine tools: investigation,modeling and validation

Virtual simulation and optimization of the dynamic behavior of machine tools in the development phase is required to satisfy the increasing demands on machine tool performance. While mass and stiffness properties can be simulated with sufficient accuracy, often no suitable damping models are available for the components of machine tools. The commonly used linear damping models are predominantly linear hysteretic or viscous models. However, the linear damping models are often not appropriate to reflect the occurring nonlinear effects in machine tools with the required accuracy. The reason for these nonlinearities are predominantly the friction forces in feed drive components. To resolve these deficits, the friction in feed drive components is comprehensively investigated in this paper, models for friction forces are identified and coupled with a reduced, flexible multi-body system. With the identified friction models the measured friction curves can be reproduced very precisely. The coupled, reduced, flexible multi-body model allows to simulate the nonlinear effects and to predict the dynamic behavior of machine tools with high accuracy. Consequently, a further important step towards accurate virtual simulation of machine tools is made.     

Double ballbar test for the rotary axes of five-axis CNC machine tools

In this paper a new method that uses the double ballbar to inspect motion errors of the rotary axes of five-axis CNC machine tools is presented. The new method uses a particular circular test path that only causes the two rotary axes to move simultaneously and keeps the other three linear axes stationary. Therefore, only motion errors of the two rotary axes will be measured during the ballbar test. The theoretical trace patterns of various error origins, including servo mismatch and backlash, are established. Consequently, the error origins in the rotary block can be diagnosed by examining whether similar patterns appear in the motion error trace. The method developed was verified by practical tests, and the servo mismatch of the rotary axes was successfully detected.     

Effect of the lubrication-cooling technique, insert technology and machine bed material on the workpart surface finish and tool wear in finish turning of AISI 420B

The paper is focussed on the effects produced by cutting operations on workpiece surface finish and tool wear. To this end, finish turning of AISI 420B stainless-steel was carried out under wet, minimum quantity of lubricant and dry cutting conditions, using both conventional and wiper technology inserts, on turning centres equipped with beds made in polymer concrete and cast iron. The workpiece surface finish and tool wear versus cutting volume were measured, and the results analysed and discussed in detail. The most significant results were: (i) the lubrication-cooling technique does not significantly affect the tool wear, whilst wet cutting produces the worst surface finish, (ii) the wiper inserts allow obtaining of the best surface finish, and (iii) the use of polymer concrete bed leads to an improved behaviour in terms of tool wear and surface roughness.     

An investigation of surface damage in the high speed turning of Inconel 718 with use of whisker reinforced ceramic tools

The paper presents the results of an investigation of surface damage produced by whisker-reinforced ceramic cutting tools in the finish turning of Inconel 718. The effects of the cutting parameters, of the tool wear and of the coolant condition on damage to the machined surface was investigated experimentally. The surface generated by machining was examined by use of both a scanning electron microscope (SEM) and a high resolution scanning electron microscope (HRSEM). This showed the regions of the surface that were damaged to contain both geometric defects and changes in the metallurgical structure of the subsurface. The types and the extent of the surface damage were found to be dependent upon the cutting parameters, the size of the wear land and the coolant conditions. The extent and the character of the coarse-scale and the fine-scale damage were analyzed on 72 specimens for which the cutting speeds, feed rates and coolant conditions (wet and dry) and the degree of tool wear differed. The types of damage that occurred in the form of micro-cracking and breakage, plastic flow, cavities, side flow and built-up edges are discussed.     

A study of back cutting surface finish from tool errors and machine tool deviations during face milling

The surface finish of mechanical components produced by face milling is given by factors such as cutting conditions, workpiece material, cutting geometry, tool errors and machine tool deviations. The contribution of the different tool teeth to imperfections in the machined surface is strongly influenced by tool errors such as radial and axial runouts. The surface profile of milled parts is not only affected by chip removal due to front cutting, but also by back cutting, which must be taken into account when predicting surface roughness. In the present work, the influence of back cutting on the surface finish obtained by face milling operations is studied. Final part surface roughness is modelled from tool runouts and height deviations that affect the surface marks provoked by back cutting. Round insert cutting tools and surface positions defined by cutter axis trajectory are considered, and milling experiments are developed for a spindle speed of 750 rpm, depth of cut of 0.5 mm and feeds from 0.4 to 1.0 mm/rev. Experimental observations are compared with the theoretical predictions provided by the surface roughness model, and good agreement is found between both results. Surface imperfections caused by front and back cutting are analysed, and discrepancies between experiments and numerical predictions are explained by undeformed chip thickness variations along the tool tooth cutting edge, the tearing of the workpiece material, and fluctuations in the feedrate and height deviation during machine tool axis displacement.     

组合机床自动控制PLC程序设计实例

本文结合一具体实例,介绍了组合机床自动控制的PLC程序设计方法,它在工程设计中具有一定的实用价值。     

数控机床电气传动部分故障诊断专家系统的设计与实现

本文开发了数控机床电气传动部分故障诊断的专家系统，介绍了系统的结构，系统运行表明，设计合理，可靠性高。     

A machining test to calibrate rotary axis error motions of five-axis machine tools and its application to thermal deformation test

This paper proposes a machining test to parameterize error motions, or position-dependent geometric errors, of rotary axes in a five-axis machine tool. At the given set of angular positions of rotary axes, a square-shaped step is machined by a straight end mill. By measuring geometric errors of the finished test piece, the position and the orientation of rotary axis average lines (location errors), as well as position-dependent geometric errors of rotary axes, can be numerically identified based on the machine׳s kinematic model. Furthermore, by consequently performing the proposed machining test, one can quantitatively observe how error motions of rotary axes change due to thermal deformation induced mainly by spindle rotation. Experimental demonstration is presented.     

机床的数控化改造与模块化设计

分析了机床的模块化设计在机床的数控化改造中的意义 ,提出了机床的模块化设计与机床的数控化改造的结合在机床工业可持续发展中将发挥巨大的作用     

组合机床中伺服系统总线网络的设计与研究

分析和讨论了应用CAN总线的技术优势和主要特点.遵循CAN2.0B协议设计了适合于组合机床伺服系统网络的应用层协议和网络的监控系统.实验结果证明了设计的可行性.     

数控机床主轴的超音速火焰喷涂与耐磨性

采用超音速火焰喷涂的方法在数控机床主轴表面制备了纳米Ni60-TiB2复合涂层和常规Ni60-TiB2微米复合涂层,运用扫描电镜(SEM)、X射线衍射仪等研究了复合涂层的显微形貌、物相组成和耐磨性能,探讨了复合涂层的摩擦磨损机理。结果表明,纳米复合涂层致密、均匀,具有扁平层状分布结构,浅灰色TiB2颗粒均匀分布在白色Ni-Cr固溶体中;微米复合涂层具有层状喷涂结构,微米级的浅灰色TiB2相不均匀地分布在白色粘结相Ni-Cr之间,且Ni-Cr固溶体中并没有发现TiB2颗粒。纳米复合涂层和常规微米复合涂层的物相主要为Ni-Cr固溶体和陶瓷增强相TiB2,以及次生的TiO2、NiTiO3、SiO2和CrB相;纳米复合涂层的孔隙率小于常规微米复合涂层,而显微硬度、断裂韧性和结合强度均高于常规微米复合涂层;纳米复合涂层的抗滑动摩擦磨损性能优于常规微米复合涂层,纳米复合涂层的主要磨损机制为粘着磨损和磨粒磨损。     

An integrated prediction model including the cutting process for virtual product development of machine tools

Recently activities for shortening the development time of machine tools and demands for high-value products are consistently being increased. As a result, many studies for predicting the performance in design stage have been conducted to solve these issues. So far, most manufacturers of machine tools have verified designs excluding the cutting process, even though the main performance is the machining quality of the workpiece. Therefore, it has been required to consider together the cutting process model for analyzing the machining quality before the manufacturing of the prototype. This paper presents an integrated dynamic model considering the all interaction of the machine structure, the control system, and the cutting process. The modal truncation technique using the steady-state dynamic analysis in a selected location and frequency range of interest is applied to increase the efficiency of mechatronics simulations including the cutting process. In particular, this proposed prediction model allows accurate design verifications for high-speed machines because it reflects the influences of the high inertia forces and the contour errors caused by high feed rate. Several peripheral milling applications were demonstrated in order to show the feasibility of the proposed prediction model, and we confirmed the superiority of prediction by comparing the simulated and measured results in high feed milling.     

690合金腐蚀疲劳裂纹扩展研究

基于DCPD方法测量了690合金在室温空气、325℃空气和325℃除氧超纯水中的疲劳裂纹扩展速率。试验结果采用Priddle模型进行拟合分析,得到690合金在3种条件下疲劳裂纹扩展的门槛应力强度因子幅值ΔK_(th)和失稳断裂应力强度因子Kc。结果表明,高温水环境下,疲劳裂纹萌生和扩展加快,这可以用滑移-溶解机理解释;高温下,材料强度下降,ΔK_(th)和Kc也下降,高温加速了材料的疲劳断裂。SEM断口形貌表明,空气中的疲劳断口观察到明显的滑移台阶,疲劳破坏形式为穿晶断裂;高温水下的疲劳断口则同时出现穿晶和沿晶开裂,为混合型断口特征。     

基于DSP56F805的数控机床伺服系统监控的设计

针对数控机床伺服系统，设计和研究了监测的方法；并结合新型DSP56F805实现了对系统变量监测和实时控制的功能。