基于正交设计的螺纹径向中径差分析

内螺纹是零件中的重要部分,加工失败或精度降低均无法实现无间隙的完美装配.径向中径差作为评价内螺纹质量的重要参数,对内螺纹的加工质量影响很大.在实际生产中,由于攻丝生产条件恶劣,难以准确控制螺纹的径向中径差.本文基于正交试验设计分析了钝圆半径、主轴转速、切削锥长度三个因素对Al7075攻丝时径向中径差的影响,并通过极差分...     

在钛合金上攻丝时的切削力和精度

研究了在钛合金上攻丝时丝锥的几何参数对扭矩和螺纹中径的影响。在钛合金上攻丝时,对扭矩和螺纹中径影响最大的一些参数是:侧后角、切削锥角和切削锥后角。本文还确定了丝锥的最佳几何参数。     

大螺距螺纹丝锥

<正> 用丝锥切制大螺距螺纹时,螺纹中径不易保证,第一、二、三圈的牙形被削短。这是由于标准丝锥第一个切削刀齿的截面较宽,在切削开始时出现了较大的轴向力和圆周力所致。勃良斯克汽车厂试制了一种丝锥(苏联发明证728967,916033),其切削部分刃齿1上开有沟槽2。沟槽的深度从锥端到校准部分逐渐减小,沟槽的铲磨量b_2等于切削锥部铲磨量b_1。在2170型立式钻床上对M18×2.5丝锥进行了试验。丝锥切削部分长度为25毫米,所加工     

基于AdvantEdge FEM的高速钢丝锥攻铝合金的参数优化

采用Pro/E并改变丝锥前角和锥角,对丝锥进行三维建模,三维切削仿真软件为Advant Edge FEM。利用多指标正交试验设计法,将丝锥切削过程中的温度、扭矩及轴向切削力这三个指标的最大值作为攻丝性能评价指标,对高速钢丝锥切削铝合金进行数值模拟及丝锥参数优化。通过试验可知,当高速钢丝锥前角为10°、锥角为8°、主轴转速为900r/min时,攻丝性能最佳。     

梯形螺纹成组丝锥的改进设计

梯形螺纹成组丝锥的改进设计汉中３１５７厂（陕西汉中７２３００７）杨晓峰１．不等径梯形螺纹成组丝锥的加工特点成组丝锥的设计可分为不等径设计和等径设计。不等径成组丝锥在攻削螺纹时，由于每一锥的中径不等，丝锥各个切削刃在加工时同时工作，所以切削阻力很大（见...     

基于AutoLISP程序的成组不等径丝锥设计

使用成组不等径丝锥攻螺纹,可显著提高螺纹的精度和降低表面粗糙度值,我公司经常有客户定制二支一组、三支一组、四支一组等成组不等径丝锥。为了合理、快速地确定出头锥、二锥的大、中、小径名义尺寸,依据设计原则（分配各锥在螺纹加工中的负荷量：二支组一锥承担的切削面积为75％、二锥为25％,三支组一锥承担的切削面积为60％、二锥为30％、三锥为10％,确保顶刃、侧刃切削厚度一致）。我们利用AutoCAD提供的AutoLISP程序二次开发功能编写了一个实用程序,可以快捷地得到各锥大、中、小径名义尺寸。现将该方法介绍如下：     

大尺寸内螺纹单锥攻丝

本文指出目前大尺寸多锥内螺纹丝锥攻丝困难,质量差。改进后的新丝锥为单锥,切削锥为四扣,螺纹型面大,刃口锋利,磨擦力小,入扣容易。校正部分比原丝锥缩短5～20毫米。在丝锥制造工艺中采取了控制回火温度和控制硬度两项措施。对锻造刀具的毛坯,注意控制碳化物的偏析。采用这种新丝锥攻丝操作中应注意控制偏摆量,最大值不应超过0.6毫米;加大螺纹底孔,采用螺纹内径上限;采用新的冷却液——极压油。图3。     

难加工材料攻丝用的丝锥

<正> 用丝锥在难加工材料上攻通孔螺纹,特别是盲孔螺纹时,由于其韧性较高,因而会产生很多困难,而且,不同材料须采用不同结构和刃磨几何形状的丝锥,这不仅给丝锥的选择带来麻烦,而且增加了丝锥的品种规格和制造难度。本文推荐的丝锥可用在各种不锈钢、耐热钢、高锰钢和合金上加工出H7级精度M4～M36的基本螺纹。该丝锥的主要特点是:从第二锥开始减小中径的铲磨量,以改善头锥攻丝后的二锥拧入时的定心条件;增加切削锥的长度,以减小切削力和中心孔尺寸,从而改善采用成组丝锥和安全卡头在机床上攻丝时的定心条件;最后一锥的螺纹牙形不铲磨。     

调质钢内螺纹采用挤压成形工艺研究

据国内外资料报道,采用挤压丝锥加工内螺纹工艺均偏重于加工有色金属及高延展性材料,而且孔径大多在Φ22mm以下,深径比一般均小于2。所以如果用挤压丝锥加工抽油杆接箍内螺纹(材料为45钢,调质硬度HRC16～23,内螺纹直径Φ24～35mm,深度80mm,螺距2.54mm,要求表面粗糙度达到R_σ10)时,则挤压丝锥寿命低,内螺纹表面粗糙度差,这是生产上普遍存在的问题。为此,我们对内螺纹挤压工艺进行了系统的研究,并研制了高效能的挤压丝锥和润滑油,以提高接箍内螺纹的挤压成形效率和质量。一、挤压丝锥的工作过程和磨损机理研究 1.挤压丝锥的工作部份由前锥部和校正部所组成。丝锥前锥部的螺牙在工件表面上依次挤压出螺纹,     

成组梯形螺纹拉削丝锥各部分直径的计算

文中阐述了梯形螺纹多支组成组拉削丝锥的切削负荷分配方案,以及各支丝锥的大径、中径的计算方法.并举例说明梯形螺纹三支组成组拉削丝锥大径、中径的计算过程.     

基于主成分分析的BP神经网络内螺纹冷挤压成形质量预测

根据冷挤压内螺纹成形中径、螺距、牙型半角和牙高率等来综合评定内螺纹的成形质量等级,并基于BP神经网络对其进行预测。在BP神经网络预测模型数据前处理过程中,采用主成分分析方法以提取影响内螺纹冷挤压成形质量的主要因素,消除各影响因素之间的线性相关性。试验结果表明,与传统的BP神经网络相比,采用该方法的BP神经网络模型,简化了网络结构,提高了收敛速度及预测精度,能准确实现内螺纹成形质量等级的预测,从而为内螺纹质量的检测提供了一条新途径。     

基于FANUC系统B类宏程序的内外螺纹的数控铣削加工

数控机床使用丝锥攻丝、板牙套扣等常规方法虽可进行内外螺纹加工,但是一种规格的丝锥或板牙只能加工一种规格的螺纹,一般只能加工单线螺纹,多线螺纹几乎无法加工。论文利用FANUC数控系统G02/G03螺旋插补和B类宏程序功能,通过M37×Ph5P2.5实例,对刀、计算后编制宏程序,完成了内外螺纹的数控铣削加工,此加工方法不受螺纹直径、螺距大小、旋向、线数、工件复杂程度的影响,螺纹刀具品种也可以变少,适用性较强。     

Electromagnetic superposed forming of large-scale one-dimensional curved AA2524-T3 sheet specimen

This study proposes a methodology for helical mill-grinding of tiny internal threads made of hard brittle materials such as SiCp/Al composites. The methodology uses the helical mill-grinding method incorporating with a diamond form-grinding wheel. A mathematical model is established to predict thread form errors and provide a rational range of wheel parameters, such as variation of tool profile angle Δα and ratio of the wheel diameter to the thread major diameter η. Based on the methodology, a grinding wheel is developed for processing the M2 internal threads in a validation experiment. The study demonstrates that an M2 internal thread made of the SiCp/Al composite of 45% SiC volume fraction is successfully machined in 5 min with pitch error <0.08% and angle error <0.3%. The thread profile on the pitch diameter is within the axial equivalent tolerance zone (0–0.016 mm), which indicates that the thread precision reaches the H4 level.     

挤压丝锥结构参数对内螺纹冷挤压成形过程扭矩的影响

将内螺纹冷挤压成形过程分为三个主要阶段,并将成形过程扭矩最大值作为标定整个成形过程扭矩的指标,得到其理论计算公式,并在得到试验验证的基础上,研究分析了挤压丝锥各结构参数(挤压锥部长度、校正部长度、挤压锥角、铲背量、棱齿数、大径及螺距)对其成形过程扭矩的影响规律。     

Monitoring of thread quality when tapping nodular cast iron with TiN-coated HSS cutting taps

Tapping is a widely employed but complex manufacturing process in which a multi-toothed tool, known as a tap, cuts a mating thread when driven into a hole. In this paper, the experiments, statistical analysis and the on-line implementation of a new thread quality monitoring system are presented for a tapping process in high-speed conditions. A multivariate statistical process control chart, for each tap, is presented based on the principal components of the torque directly measured from spindle motor drive. The on-line implementation of the multivariate chart provides tap wear warnings and alarms before the process starts producing unacceptable screw threads. The system is cost-effective since the tapping process can be run automatically without any operator intervention, does not require intrusive sensors, does not result in false negatives (defects) and provides an acceptable number of false positives.     

非最佳量针测量螺纹的定义中径

通过最佳和非最佳2组三针测量同一螺纹的中径,实现了对螺距、牙型半角都有误的螺纹的单一中径和中径的准确测量.介绍了不需要按传统的三针测量方法复杂地修正程序来求解修正值的新方法,并对该方法进行了不确定度分析.该方法简便易行,非常适合工厂加工过程中精密螺纹工件中径的精密测量和工厂计量室对螺纹塞规周期检定中的中径测量.     

高速微铣削铝合金表面粗糙度的多指标正交试验研究

利用小型高速精密微铣削机床在6061铝合金表面加工微沟槽结构,对加工后的试件表面质量进行研究,以试件表面粗糙度Ra、Rz值为衡量指标,利用正交试验方法分析主轴转速、刀具悬伸量、进给量和轴向切深等因素对表面质量的影响。试验结果表明：试件表面粗糙度值整体变化趋势从大到小依次为中线区、顺铣区、逆铣区。主轴转速对表面粗糙度影响最显著,而其他因素随着表面质量要求的不同有所变化。综合考虑表面质量要求,最优组合为:刀具悬伸量为18mm,轴向切深为10μm,进给量为30mm/min,主轴转速为48 000r/min时,试件表面粗糙度最小,此时表面粗糙度Ra值为0.075μm,表面粗糙度Rz值为0.579μm。     

优化套管螺纹载荷分布特性的方法

根据套管螺纹的结构和受力特点 ,建立了套管接头在轴向拉力作用下的计算模型 ,分析了载荷在各牙螺纹上的分布特点。在此基础上 ,提出了优化套管螺纹载荷分布特性、减小应力集中的具体方法 ,并依据实用性 ,从螺纹的加工方便考虑 ,提出了外螺纹全部和内螺纹大部分保持螺距不变 ,仅对内螺纹两端 2～ 4牙螺纹变化螺距的近似优化方案。通过有限元方法模拟了优化方法的效果 ,验证了这种方法的可行性。研究结果对改进套管螺纹设计 ,提高套管螺纹的连接质量具有参考价值     

Investigation on the effect of cutting fluid pressure on surface quality measurement in high speed thread milling of brass alloy (C3600) and aluminium alloy (5083)

The quality of a machined finish plays a major role in the performance of milling operations, good surface quality can significantly improve fatigue strength, corrosion resistance, or creep behaviour as well as surface friction. In this study, the effect of cutting parameters and cutting fluid pressure on the quality measurement of the surface of the crest for threads milled during high speed milling operations has been scrutinised. Cutting fluid pressure, feed rate and spindle speed were the input parameters whilst minimising surface roughness on the crest of the thread was the target. The experimental study was designed using the Taguchi L32 array. Analysing and modelling the effective parameters were carried out using both a multi-layer perceptron (MLP) and radial basis function (RBF) artificial neural networks (ANNs). These were shown to be highly adept for such tasks. In this paper, the analysis of surface roughness at the crest of the thread in high speed thread milling using a high accuracy optical profile-meter is an original contribution to the literature. The experimental results demonstrated that the surface quality in the crest of the thread was improved by increasing cutting speed, feed rate ranging 0.41–0.45 m/min and cutting fluid pressure ranging 2–3.5 bars. These outcomes characterised the ANN as a promising application for surface profile modelling in precision machining.     

Non-contact inspection of internal threads of machined parts

During the manufacturing process of mass-produced automotive parts, millions of internal threads are produced annually by each automaker. The manufacturers invest a lot of effort and resources to improve the quality of the threads by inspecting their features, mainly by using manual contact gages. The majority of manufactured threads are used in threaded joints that assemble two mechanical parts. However, there are threads that have additional functionality, for example, an automotive spark plug. Recently, automotive designers have found that the angular direction of the spark plug inside the combustion chamber affects the efficiency of the engine. Hence, the manufacturers are interested in measuring the exact position of the thread starting point, allowing them to position the plug in the right direction during the plug assembly process. Our technique allows precise measurement of the thread starting point and meets this requirement. In order to improve the quality of internal threads, it is essential to measure the threads dimensional features. It is also important to inspect its internal surface for defects such as the existence of burrs, thread discontinuities, or internal porosity defects. The paper introduces two novel non-contact electro-optical techniques for inspecting small-size internal threads. The first one enables in-process internal thread geometrical measurements using a high-precision laser sensor which utilizes a motorized periscope. The second technique is based on image processing and uses innovative machine vision; a line-scan technique which uses a CCD camera with a “sight pipe” panoramic optical device. The two methods are complementary; together they allow the practical inspection of all needed features of the internal thread. The methods were tested successfully.