钻床夹具精度分析的新方法—实态法

在钻床上使用夹具加工工件时,被加工孔的位置精度,会受到诸多因素的影响。其影响因素有工件定位误差T_D,夹具制造误差T_z,夹具安装在机床上的安装误差T_A,由于被加工件的变形、夹具定位件、导向件、刀具的磨损、以及刀具的偏斜引起的随机误差T_S等。当被加工孔的位置精度有一定要求时,要用尺寸链原理综合分析各误差的累积关系,使所设计的夹具能保证工件的加工精度要求.在误差尺寸链的各环中,工件被加工孔的仕置精度T_0为封闭环,影响加工精度的各误差T_1为组成环。由于各误差的性质、工件或夹具元件的加工批量和加工方法的不同,使得尺寸分     

高精度偏心深孔加工旋转夹具

汽车发动机摇臂轴两偏心深孔的加工,要求保证两端两孔的位置精度和偏斜精度,提高效率和降低成本。解决以上问题,需要相应的加工设备和专用工装。本旋转夹具综合考虑了偏心深孔加工的特点以及钻孔位置精度、偏斜精度的工艺要求,实现了工件一次装夹完成两偏心深孔的高精度加工,提高了效率,降低了成本。     

简易钻孔夹具三则

1.分离式钻孔夹具 我厂为意大利生产的工艺包缝机零件钩针,其2—φ1mm孔在不同的方向,并且2个孔之间中心线的位置精度有要求。为了保证加工精度,提高工效,设计了图1所示的分离式钻孔夹具。该套分离式钻孔夹具,加工工件时只需一次安装定位即可巧钻上述不同位置、不同角度的两个孔。减少定位误差,保证了加工     

多孔异形小件车削夹具

在机械制造业中,经常需要进行多孔异形小件的孔加工,且孔的形状精度与位置精度要求较高。我们研制出一种车削夹具,使之可以在车床上完成这些孔的加工,比在镗床上效率高,既经济又方便。 该车削夹具由9种零件组成,如图所示。车削夹具体9安装在LC400主轴上,工件2可以在1孔     

液压阀体主阀孔车削加工夹具设计应用

山西奥凯液压机械有限公司承接了一批液压阀体零件加工任务,由于该零件外形架构复杂,其主阀孔尺寸和位置精度要求高,需要车削加工完成,公司现有CDE6140A车床通用夹具无法满足生产加工要求。针对以上问题设计了一款液压阀体主阀孔车削加工专用夹具。本文主要对阀体主阀孔车削加工夹具的设计方案进行了详细说明,并详细阐述了定位机构、夹紧机构已经夹具的使用方法。该夹具设计原理对不规则复杂形体零件孔的车削夹具设计有重要的借鉴意义。     

基于加工中心的飞锤铣削气动夹具设计

飞锤零件内外开档尺寸精度及其位置精度要求较高，特别是2-?8孔的轴线与开档底距离及其与此开档侧面的垂直度等参数，对整机的装配及机台的后续使用至关重要。在使用加工中心机床基础上，设计制作了一套基于程控式的飞锤内外开档铣削夹具。首先从零件结构及其加工精度入手，分析了夹具工作流程，确定了夹具整体结构，并设计了定位部件、夹紧部件及控制部件，最后进行夹具的装配和实际应用。使用结果表明，该夹具能满足设计要求，做到了一次装夹，一次切削加工成形，获得了较高形状和位置精度，工序过程能力指数显著提高，产品质量极大提升。     

逆向思维在加工工艺中的应用

我公司为用户设计制造的在加工中心上用于加工斜孔的专用夹具。其设计结构较紧凑,且加工精度要求非常高,最为突出的是工件定位基准面为斜面,相关控制精度尺寸及形位公差要求较高,给加工带来了很大困难。附图为该夹具的本体,2-25+0.0210孔为工件定位销孔,20+0.0210为对刀孔。该夹具以槽180-0.018定位。为保证定位槽与对刀孔位置及斜面上定位销孔的相对位置精度,需作一工艺孔10+0.0150,该工艺孔必须保证与斜面距离为50±0.01,与对刀孔20+0.0210在X方向孔距75.95±0.01,同时,为保证夹具的定位键与对刀孔的相对位置,工艺孔与定位键间距…     

耳片偏心孔在普通车床上的加工方法

在生产中经常遇到耳片零件,其上的孔加工通常为:划线钳工划线、钳工按划线位置钻铰孔。文中介绍了一种在普通车床上就可完成耳片零件上孔加工的夹具及其工作原理,可加工出一些孔精度要求高、而孔中心距耳片底边精度要求不太高的零件。     

一种简单实用的钻夹具

图1所示的工件，根据加工工序安排的要求，在φ85外圆径向钻2一φ14．5＋孔。由于成品件上2-φ15＋孔的同轴度及对φ27＋孔的位置度要求不大于φ0．010mm，故对本工序要求2孔的同轴度小于φ0．05mm。根据加工批量，工件的形状特点和本工序的加工精度要求，我厂设计了如图2所示的钻孔夹具，较好地保证了工件精度，并且操作方便，效率高。现将其结构特点介绍如下。工件以底面和φ27＋孔定位于夹具转动体10上，并通过开口垫12、螺母13将工件压紧在转动体10上。转动体通过对定销4定位于夹具体1上，此时逆时针转动手柄8，则凸轮螺套7向左移，推动…     

钻孔专用夹具精度技术分析

在生产中经常会遇到加工圆周均布孔的零件，如加工法兰的螺栓紧固孔、对轮的销子定位孔、带轮和齿轮等用以减轻重量的孔，而有些圆周均布孔的精度要求是比较高的。为满足零件的设计要求，提高机加工作业效率，采用了钻圆周均布孔的专用夹具。图1是加工齿轮圆周均布孔的专用夹具。     

喷油嘴微孔电火花加工机床机电控制系统设计

喷油嘴喷孔加工质量直接影响发动机的燃料喷射和燃烧性能。喷油嘴喷孔机械钻削加工已难以适应高压力、微细喷孔喷油嘴发展的需要。微细电火花加工喷油嘴喷孔具有无宏观加工力、无毛刺、可加工微细喷孔以及可在热处理后加工等优点。文章结合自主设计研发的喷油嘴微细孔电火花加工机床,设计了机床的机电伺服控制系统,并进行了控制系统性能优化,进行了喷油嘴微细喷孔的电火花加工实验和工业应用,较好地满足了喷油嘴微细喷孔加工的工业需求。     

A new tool wear estimation method based on shape mapping in the milling process

In the milling process, tool wear has a great influence on product machining quality, especially for a difficult-to-cut material. In this paper, a new approach based on shape mapping is proposed to acquire tool wear in order to establish an off-line tool wear predicting model for assessing the degree of wear and remaining useful life. The new approach maps tool wear shape into a metal material by milling holes mode after finishing each of the machining experiments. The metal material has low influence on tool wear compared to the experimental material. Thus, a series of mapped holes, which can represent the worn tool information, are formed on the metal material when finishing all milling experiments. These mapped holes on the metal material are analyzed according to all types of milling cutters in order to establish the relationship between the characteristic parameters of these mapped holes and tool wear. According to the established relationship, the characteristic parameters of these mapped holes are measured on the coordinate measure machine. The tool wear of each machining experiment can be obtained from the measured characteristic parameters of these mapped holes. The new tool wear estimation method does not require the stoppage of the machine tool and the removal of the cutter to measure tool wear in the process of conducting tool wear experiments. The new method can increase the machine tool efficiency of tool wear machining experiments and provide an efficient way to acquire tool wear in the process of establishing an off-line tool wear predicting model. In order to verify the new tool wear estimation method, a series of machining experiments were conducted on the five-axis machining center for cemented carbide cutting tool milling stainless steel. Experiments show that the shape mapping strategy of tool wear can allow for an effective assessment of tool wear and indicate good correlation with the expected wear characteristics and easily conduct tool wear experiments.     

基于全微分法解平面尺寸链及孔系坐标公差的计算通式

在工艺尺寸链中,平面尺寸链较为繁杂,在箱体孔系、斜孔加工及装配工艺中常需解算。本文以微分学原理对尺寸公差进行系统处理,不仅简化了分析计算,而且由于同时考虑了常被忽略的角度误差,极大的提高了计算的精确性和合理性,并由此首次推导出孔系坐标公差的极值法公式和概率法公式,极大的方便了机制工艺人员的工艺工装设计。     

离心式压缩机空间交叉进气孔加工工艺研究

阐述了离心式压缩机机壳进气孔的加工工艺。这些孔为空间交叉,通过前期的分析,后期的探索与实践,对加工中的每一步精确地控制,很好地保证了空间交叉孔的位置度和直线度要求。     

Design of ECM tool electrode with controlled conductive area ratio for holes with complex internal features

The design method of electrochemical machining (ECM) tool electrode with controlled conductive area for the machining of holes with given complex internal features was presented in this paper. Such holes were difficult to machine with traditional mechanical machining methods. In authors’ previous work, it has been proved that electrochemical machining (ECM) using tool electrode with controlled conductive area ratio was effective to machine many kinds of complex holes. However, it is considered that the inverse problem, i.e., designing of suitable tool electrode for given internal feature is of great importance for practical application. Therefore, in this work, the proposed ECM process was modeled to investigate the electric potential and current distribution in the electrolyte and on the electrodes’ surface, and the evolution of inner hole profile. Then, the relationship between conductive area ratio and the machining depth was investigated by a set of fundamental simulation experiments. Simulation result showed that suitable tool electrode with specific helical conductive area can be designed for the machining of hole with given internal feature. A prototype tool electrode with non-uniform conductive area ratio from its tip to the root was fabricated and used in the verification experiment. The machining result showed that a free-formed hole was successfully shaped and the inner hole profile is in well accordance with the given internal feature.     

ROTARY ULTRASONIC MACHINING OF CARBON FIBER-REINFORCED POLYMER: FEASIBILITY STUDY

Carbon fiber-reinforced polymer (CFRP) has been widely used in aircraft components, automotive parts, and sporting goods. Hole machining is the most frequently employed operation of secondary machining for fiber-reinforced composites. However, challenges (delamination, splintering, burr, short tool life, low machining precision, and low surface quality) still remain for their widespread applications. Rotary ultrasonic machining (RUM) is a non-conventional machining process that has been used to drill holes in composite materials. However, it has not been used to drill this type of CFRP. In this article, RUM is introduced into drilling holes in this type of CFRP for the first time. The feasibility to machine carbon fiber-reinforced epoxy using RUM is investigated experimentally. Chips, edge chipping, surface roughness, tool wear, and thrust force were measured. Effects of RUM process variables (rotation speed, vibration amplitude, and feedrate) on thrust force and surface roughness were studied. Results showed that RUM could be used to drill holes in CFRP with high productivity and low tool wear. A better surface was produced by higher rotation speed and lower feed rate.     

线切割特殊加工方法的探索

线切割主要用于加工模具、电火花的工具电极以及各种型孔、样板和成形刀具等。对于一些特殊零件需要用特殊的加工方法。本文重点介绍了斜导柱孔、上下异形和上下圆弧的过渡这3种特殊零件的特殊加工方法,以期给从事线切割加工的操作人员提供加工思路。     

汽车玻璃钢化风栅成形器五轴加工刀轴矢量插值

为了解决汽车玻璃钢化风栅成形器五轴加工时刀轴矢量频繁变换造成冲击或发生干涉等问题，提出一种刀轴矢量插值方法。根据被加工曲面的几何形状和误差要求确定刀触点，根据被加工曲面的微分几何性质确定刀轴矢量的后跟角和摆转角。在已确定刀触点处的刀轴矢量的基础上，采用空间矢量光滑插值方法获得一系列中间位置刀轴矢量使刀轴变化较均匀。以货车前挡风玻璃钢化风栅成形器的一个拼镶块工作表面和风栅孔五轴NC加工为例进行仿真。结果表明，该刀轴矢量光顺方法可以避免刀轴方向频繁变换，同时也可有效地提高加工精度。     

An improved tolerance charting technique using an analysis of setup capability

The tolerance charting method enables the calculation of working tolerances in machining process planning. The method has been used as a basic tool for analysing process plans for many decades. Process capability in tolerance charting is modelled using the tolerances of the working dimensions. The literature shows that machining process capability can be analysed from the point of view of surface position errors. During setups, it is possible to perform decomposition into two surface position tolerances: a datum surface position tolerance and a machining surface position tolerance. This type of analysis has the advantage of producing simplified tolerance chains. This paper provides an adaptation of the tolerance charting technique that uses a capability model based on datum and machining surface position tolerance. The results show an improvement in the working tolerance stackup that reduces the capability required for productive resources. As a result, reductions in manufacturing costs can be achieved. The proposal is valid for manual or computer-assisted techniques.     

An experimental investigation of the effect of coatings and cutting parameters on the dry drilling performance of aluminium alloys

As a result of the need to automate assembly in the aircraft industry, along with economic and ecological reasons, industry and research institutions have been pushed to develop dry drilling for aluminium alloys to eliminate the need for cooling fluids. The main difficulties in dry drilling are accelerated tool wear due to workpiece material adhesion on the tool and the formation of bigger-sized burrs. This paper describes an experimental research study on machinability in the dry drilling of aluminium alloys and on the potential of the new design of tools and coatings. Dry drilling tests were performed using uncoated drills and two different coatings produced by means of an arc evaporation PVD process. Experiments consisted of machining with a 10-mm diameter three-edged drill to produce 25-mm deep holes. Tool wear evolution and burr size were analysed, as well as the impact of the process parameters on torque, power, feed force and tool temperature.