卡盘的修复

由于机床卡盘承受很大的夹紧力和切削力,卡盘零件极易磨损。磨损后的卡盘主要缺陷是工作精度超差和夹紧时卡爪呈喇叭口。因此,降低加工精度、削弱了夹紧的刚性。常用的一种综合修理方法,是对已磨损的卡盘卡爪进行自身修磨。修磨工艺的关键,是卡爪修磨时的夹紧方法。由于受到卡盘结构的限制往往     

浮动式六爪卡盘的改制与应用

针对三爪卡盘夹持薄壁工件时易变形的问题,介绍了一种在三爪卡盘基础上改制出原理可靠、结构简单的浮动式自定心六爪卡盘的方法,实现了改制后的卡盘在六爪联动同时能保证浮动接触、定心夹紧和稳定可靠,减少了薄壁工件夹紧变形。检测数据证明,浮动式自定心六爪卡盘能极大提高薄壁工件的加工精度。     

盘类工件的加工

1.盘类工件的关键在装夹 一般盘类工件材料较杂,有铸铁、锻件、也有锯下来或电焊、气割件,但它们共同的特点厚度余量都在5～10mm左右,大多数车工都用三爪卡盘夹持余量部分。然后一次车削成形,由于夹持长度少,而车刀的起始点离支点远,车削时,当切削力乘上力臂值大于夹紧力时,轻则工件走动,严重时工件从卡盘上掉下来,造成事故,所以车工师傅只能用较小的切削用量加工,劳动生产率甚低。     

薄套类零件自动夹紧拆卸倒角装置的设计与应用

本文针对薄套类零件的加工特点详细阐述了采用凸轮机构的原理、运用车床卡盘旋转运动离心力的原理,自行设计并制造了套类零件的倒角装置,此装置的原理是利用凸轮卡爪内的弹簧对工件夹紧产生预紧力,车床卡盘旋转时工件与斜面凸轮卡盘产生向心摩擦力,当车床卡盘高速旋转刀具或钻头与零件接触时,零件产生的塑性变形力瞬间使凸轮卡爪的夹紧力增大,此时工件的塑性变形力与工件夹紧力相等,解决了手工装夹产生的一系列的问题。应用到了实际生产中,不仅提高了产品质量和劳动效率,而且降低了操作者的劳动强度。此装置装夹方便快捷实现了自动夹紧、自动退料的功能。     

带有力放大机构的重型卡盘设计

改进设计了用于夹持≥10 t工件的重型卡盘,对其夹紧能力、极限转速等性能作了相关分析。为了方便人工操作,设计了卡爪的增力机构,对其动态卡紧力的大小及极限转速进行探讨。研究成果用于63 t级重型数控机床卡盘的设计。     

旧三爪自定心卡盘精度的提高

三爪自定心卡盘的精度直接影响所加工工件的精度。我们对旧三爪自定心卡盘采取了一些改造措施,从而提高了所加工工件的精度。现介绍如下。 三卡自定心卡盘的作用是定位和夹紧。由于卡爪的平面螺纹配合间隙增大和卡爪工作面的磨损,所加工工件的精度也就受到影响。我们给旧三爪自定心卡盘配上用中碳钢制成的附加软爪.并根据工件进行临床加工,即可弥补旧三爪自定心卡盘的平面螺纹配合间隙增大和卡爪工作面磨损的两个缺陷。原卡爪只起夹紧作用,其定位任务则由调整正确并固定在卡盘上的软爪工作面来完成。软爪先进行粗安装,然后试加工一个工件,测出工件的尺寸和位置精度,再对软爪最终调整准确。     

软爪自定心卡盘的使用及工作原理

正自定心卡盘的夹紧定位精度国家标准有规定,根据其规格大小,一般在0.06~0.16 mm,使用磨损后,这个误差会增大,由于自定心卡盘使用方便,人们往往在加工精度要求(主要指几何精度)高于卡盘所能达到的精度工件时也使用,于是便产生了我们经常使用的所谓"软爪自定心卡盘"。软爪自定心卡盘是在原来卡爪的夹持工件部位焊接(或堆焊)上一层金属,然后根据加工工件的直径大小再车削一刀。焊接一层金属的目的一般有两方面:一是因为卡爪加工不同直径的工件要经常车削,焊上一层金属可延长卡爪的使用寿命;二是焊接的金属一般较软(这也是软三爪名称的原由),可避免卡爪将工件夹坏。软爪自定心卡盘可提高被加工工件的同轴度,一般可保证同轴度误差小于     

数控车床液压卡盘软爪车削夹具

数控车床一般用液压卡盘来夹持工件.液压卡盘通常都配有不淬火的卡爪,我们称之为软爪.软爪分为内夹和外夹两种形式,卡盘闭合时夹紧工件的软爪为内夹式软爪,卡盘张开时撑紧工件的软爪为外夹式软爪.如图1所示,软爪1是以端面齿槽与卡爪座3定位,通过螺钉和卡爪座中的T型螺母2固定在卡爪座3上.液压卡盘工作时,软爪在卡爪座的带动下,作闭合或张开运动,将工件夹紧或松开.夹持不同工件时,通过改变软爪在卡爪座上的位置来改变液压卡盘的夹持尺寸.     

普通三爪自定心卡盘加装微调盘

有一些零件的工序加工,对三爪自定心卡盘的夹持精度要求较高。通常是靠修磨三爪或敲击三个卡爪等方法校正工件,费时费力。如果在法兰盘与三爪自定心卡盘之间增加一个微调盘,使工件的径向跳动误差能靠微调来加以控制和消除,则工件校正将会事半功倍。     

三爪卡盘机构及其夹紧力模型分析

三爪卡盘的夹紧可靠特性和夹紧力大小与其机构及结构参数有关。通过对三爪卡盘机构组成、传动原理及夹持特性的分析,分别采用几何法和数值计算法来建立端面螺纹的几何模型、螺旋线方程和夹持力模型,研究影响卡盘夹紧力与夹持可靠性的结构因素和相关参数,探讨其关键问题。结果表明,利用阿基米德螺旋线的等速性设计卡盘机构的三爪来实现对工件的自定心夹紧在理论上具有合理性;低速和高速卡盘夹紧力的计算分别按静态力和动态静力平衡法建立模型比较可靠,夹持可靠性的关键是满足自锁条件,即螺旋升角小于最小摩擦角(λφ_(min)),螺旋副导程与螺纹直径之比应满足S/dπμ_(min);卡盘结构参数对夹紧力影响相对较小,高速时的惯性力使卡盘的实际夹紧力减小、可靠性降低。改善螺旋副表面质量和润滑条件可增大夹紧力,适当增大预夹紧力可减小惯性力的影响和提高夹持可靠性。     

重载锻造操作机夹持力研究

对重载锻造操作机夹持力计算的重要性和困难性进行分析,指出钳口表面有别于一般意义上的机械手夹持面。并将夹持装置钳口与锻件接触面之间简化为钳口凸齿与锻件挤压槽的作用,提出一种夹持力计算的思路。根据使用工况,将钳口工作分为夹紧状态和夹持状态,阐述两种状态的工作特点和作用,建立工件夹持状态下的受力模型,计算夹持状态下钳口在水平和垂直两个位置时的夹持力。用放大系数修正后的夹持力确定钳杆夹紧液压缸输出力,实现夹紧状态时钳口与工件之间形成充分的凹凸齿作用,以保证钳口夹持状态时能够输出最大夹持力矩。结合钳口与工件接触表面的结构特点和作用,提出钳口凸齿设计的思路和原则。实例计算和虚拟样机仿真证明计算结果有效。     

Factors affecting the machining accuracy of a chucked workpiece

A deviation in shape called ‘out-of-roundness’ is commonly observed in machined workpieces held by three-jaw chucks in turning operations. This out-of-roundness is due mainly to the variation in the stiffness of the workpiece-chuck-spindle system; the stiffness being higher when the cutting force is acting against a jaw and lower when acting along a jaw. This variation in stiffness of the workpiece-chuck-spindle system, termed here ‘directional orientation’, also leads to the generation of a type of parametric vibration.An attempt has been made to get rid of this effect of directional orientation by optimizing the contact between the jaw face and workpiece. Cutting tests were conducted on tapered testpeices with full contact between the jaws and the testpiece. Various contact chord lengths and spindle speeds were used. Measurements of out-of-roundness, limiting depth of cut and radial cutting force were made for analysis. Results show that where the deviation in shape of the testpiece has a three-pronged profile, and the peak at the third multiple is significant in the frequency spectrum of the radial cutting force, a contact chord length equal to the radius of the testpiece gives the optimized clamping condition.     

Chucking compliance compensation with a linear motor-driven tool system

This paper describes a system that compensates for machining errors resulting from chucking with separated jaws. In machining a chucked cylindrical workpiece, degradation in machining accuracy, such as out-of-roundness, is inevitable due to variation in the radial compliance of the chuck workpiece system caused by the position of jaws with respect to the direction of the applied force. To compensate for the machining error induced by chucking compliance, the roundness profile of the workpiece due to chucking compliance after machining should be predicted first. Then, using this prediction profile, a compensating tool feed trajectory can be generated. By synchronizing the cutting tool drive system with the rotation of the workpiece, machining errors induced by chucking compliance can be reduced. To satisfy the condition that the cutting tool feed system must provide both high speed and high position accuracy, a brushless linear DC motor is used. In this study, first, the variation in the radial compliance of the chuck workpiece system is obtained through a force-deflection experiment with a workpiece-chucked lathe. Next, using mathematical equations and the results of the cutting experiment, a workpiece profile prediction and its compensating tool trajectory are generated. Then, the configuration of the compensation system based on a linear motor is described, and a proportional integral derivative (PID) controller is designed to improve the system performance. Finally, the tracking performance of the system is confirmed by experiment. A real cutting experiment shows significant improvement in roundness.     

三爪卡盘静态夹紧力研究

用静力学的方法研究了三爪卡盘各结构参数与夹紧力之间的函数关系,并对 中外卡盘进 行了夹紧力对比实验。结果表明盘丝平面螺纹与卡爪牙弧接触部位的摩擦是影响卡盘夹紧力 的最重要的因素, 而其它各结构尺寸则影响很小。     

伸缩式对称夹具的设计

伸缩式对称夹具可以夹持不同类型不同厚度的工件,工件的厚度变化不会影响工件固定后的中心线。并且该夹具的夹持头可以缩回夹具架,该夹具还具有安装空间小,夹持力大等优点。     

Fixture Clamping Force Optimisation and its Impact on Workpiece Location Accuracy

Workpiece motion arising from localised elastic deformation at fixture-workpiece contacts owing to clamping and machining forces is known to affect significantly the workpiece location accuracy and, hence, the final part quality. This effect can be minimised through fixture design optimisation. The clamping force is a critical design variable that can be optimised to reduce the workpiece motion. This paper presents a new method for determining the optimun clamping forces for a multiple clamp fixture subjected to quasu-static machining forces. The method uses elastic contact mechanics models to represent the fixture-workpiece contact and involves the formulation and solution of a multi-objective constrained oprimisation model. The impact of clamping force optimisation on workpiece location accuracy is analysed through examples involving a 3-2-1 type milling fixture.     

锻造操作机钳口夹紧力和夹紧缸能力的计算

在锻造操作机设计中，钳口夹紧力和夹紧缸能力的计算是首要的和关键的问题，它的分析、计算、选择是否正确，对操作机整体设计至关重要。     

细长轴车削加工误差的分析

针对细长轴的车削加工。分别对在一端卡盘夹紧、一端顶尖支承及两端顶尖支承的装夹条件下车削加工时的变形进行力学分析。建立在切削力作用下产生弯曲变形的解析模型。算侧表明：逆向车削时轴的弯曲变形以及加工误差远小于同等条件下正向车削的变形和误差。     

HSK热装刀柄—刀具系统径向刚度分析

HSK热装刀柄是高速数控机床的重要通用部件之一,由于其动静态精度、刚性、可靠性、安全性等直接影响到被加工零件的质量和加工效率,因此从理论上分析各因素对系统刚度的影响有着重要意义。本文基于ABAQUS,运用FEA手段分析了不同的过盈量、夹持量、悬伸量以及转速对HSK热装刀柄—刀具系统径向刚性的影响,通过回归分析手段得到对系统刚度影响最为显著的因素。     

Slave rotation analysis of miniature inner grooved copper tube through rotary swaging process

Miniature inner grooved copper tube (MIGCT) is widely applied in industries. To overcome the weak rigidity and strength of MIGCT during stepped tubes manufacturing, rotary swaging process was selected after comparing with radial forging process. The working principle of the rotary swaging was analyzed. A rotary swaging machine, whose workpiece feeding and clamping was respectively driven by an air cylinder and a finger cylinder, was designed. Experiments indicate that the MIGCT was slave rotating with forging dies during rotary swaging. Theoretical analysis was done to investigate the reason of the slave rotation. Experiments were carried out to verify the theoretical analysis. Furthermore, the influences of push force and clamping force on rotation speed were discussed. With the increase of clamping force, the rotation speed of MIGCT decreases gradually in a constant ratio. However, the push force influences the tube rotation speed slightly. In general, it found that an optimal rotation speed of MIGCT is beneficial to the manufacture of the stepped tube.