内齿珩轮的计算机辅助几何造型

内啮合珩齿工艺是一种高效低耗的齿轮精加工工艺,所用刀具是内齿珩轮,珩轮齿面形状为渐开线螺旋面的包络面.由于该包络面形状复杂,使珩轮基体齿面形状的设计和制作成为一个难题.针对这一难题,该文提出用计算机辅助几何造型方法设计珩轮齿面.首先,根据机床要求和被加工齿轮情况确定内齿珩轮的齿数、外径、高度以及珩轮与被加工齿轮的轴距和轴交角;其次,构建内齿珩轮和被加工齿轮的运动模型,并用拉伸构型法构造齿轮的实体模型,用圆柱构造珩轮毛坯的实体模型;然后,利用几何造型技术中的集合操作,对珩轮毛坯作循环差操作,直至形成准确的珩轮模型.最后,通过沿珩轮齿宽取断面的操作,得到珩轮齿面各部位的断面形状,并标注尺寸.     

齿距偏差测量中系统误差的分离方法

德国联邦物理技术研究院(PTB)与日本计量院(NMIJ)提出了将闭环技术应用于齿距偏差的测量,用于消除测量过程中的系统误差,达到高精度测量齿距偏差的目的.通过借鉴闭环测量技术,提出了齿距偏差两步测量法用于消除齿距偏差测量中的系统误差.首先将被测齿轮安装于齿距偏差测量仪中,对齿距偏差进行初次测量;测量结束后,将齿轮在测量仪中绕轴线改变一个齿距角的位置,再次对齿距偏差进行测量.根据齿距偏差与测量系统误差的关系及两次测量数据,可以建立数学模型对齿距偏差与系统误差进行求解,达到分离系统误差的目的.分别采用闭环技术与两步法对模数为6,齿数为20与模数为4,齿数为30的两个齿轮齿距偏差进行测量,并对测量结果进行比对,单个齿距偏差值分别相差0.10μm与0.15μm.测量结果说明,两步法可以应用于齿距偏差的高精度测量,同时,其测量过程相对于闭环技术更加简单,更易于广泛应用.     

渐开线圆柱齿轮分度圆弧齿厚的测量

本文介绍一种不需考虑变位系数，以较高准确度测出渐开线圆柱齿轮分度圆弧齿厚的方法。利用该方法制成的齿厚测量装置可配置在各种测量、加工设备上，适合于对齿轮加工余量的控制及分度圆弧齿厚的精密测量。该装置已获国家专利     

浅谈硬质合金滚刀与硬齿面滚齿的设计

随着工业技术水平的提高，滚齿技术得到了很大的发展，采用硬质合金滚刀对硬齿面进行加工，革新了传统的硬齿面精加工工艺。对于高精度的磨齿齿轮来说，硬齿面滚齿能用很高的效率代替粗磨工序，切除齿轮的热处理变形，留下小而均匀的余量进行精磨，提高了磨齿效率。对于衍齿齿轮来说，在衍齿前安排硬齿面滚齿，可以切除热处理变形，达到必要的精度，再进行衍齿加工，以充分发挥衍齿工艺光整加工的特长，弥补滚齿加工的不足。对于普通精度的淬硬齿轮来说，可以用硬质合金滚刀直接进行精滚加工，以保证齿轮加工精度，是一种不可取代的齿轮加工技术。     

硬质合金滚刀与硬齿面滚齿的设计工艺

随着工业技术水平的提高,滚齿技术得到了很大的发展,采用硬质合金滚刀对硬齿面进行加工,革新了传统的硬齿面精加工工艺。对于高精度的磨齿齿轮来说,硬齿面滚齿能用很高的效率代替粗磨工序,切除齿轮的热处理变形,留下小而均匀的余量进行精磨,提高了磨齿效率。对于衍齿齿轮来说,在衍齿前安排硬齿面滚齿,可以切除热处理变形,达到必要的精度,再进行衍齿加工,以充分发挥衍齿工艺光整加工的特长,弥补滚齿加工的不足。对于普通精度的淬硬齿轮来说,可以用硬质合金滚刀直接进行精滚加工,以保证齿轮加工精度,是一种不可取代的齿轮加工技术。     

齿轮滚插齿加工过程中偏心产生的原因及检测方法

汽车行业变速器齿轮滚插齿加工过程中,由于受到机床传动链误差、夹其制造安装误差及齿坯定位基准精度影响,不可避免的产生偏心,影响齿轮加工精度。尽可能的减小偏心,将提高齿轮加工精度。     

直齿圆锥齿轮公法线长度的测量

直齿圆锥齿轮的齿厚,传统的方法是测量大端背锥齿厚,这种方法不仅测量精度很低.而且为了保证作为测量基准的背锥的精度,对齿坯加工提出了很多公差要求。象圆柱齿轮一样,圆锥齿轮的齿厚可以通过大端公法线长度来测量,此法的优点是测量精度较高,对齿坯加工的精度要求较低,其缺点是公法线长度的计算较麻烦。本文应用球面渐开线形成原理,推导了直齿锥齿轮公法线长度的计算公式。根据计算公式编好程序后,通过微型计算机可立即算出公法线长度。     

软质齿轮齿距累积偏差影像法测量

采用影像法对微小齿轮或软质齿轮齿距累积偏差,进行非接触测量,利用影像测量仪和回转工作台,采用单齿法和跨齿补点法,通过对回转工作台角度转位的分度误差补偿完成测量,提高了绝对法测量数据的合理性。对齿轮安装偏心误差、测量仪器误差和瞄准对齐误差分析,得到单齿法和跨齿补点法齿距累积偏差测量的不确定度分别为±65μm和±64μm,均满足测量精度要求。两种方法对被测塑料软质齿轮精度等级判定都为10级。相比来说,跨齿补点法测量次数更少,过程更简化。     

齿轮误差Δf_f、Δf_(pb)和Δf_(pt)的组合与选用

在切齿工艺中,齿形误差△f_f、基节偏差△f_(pb)和周节偏差△f_(pt)是由机床分齿运动误差、分度蜗杆制造和安装误差、分度蜗轮或分度盘的局部齿距误差和分齿挂轮的安装偏心及刀具误差引起的。这些误差共同影响着齿轮传动的平稳性,而在几何关系和实测统计上却又互为相关。△f_f 反映的是一齿范围内的误差,△f_(pb)和△f_(pt)反映了换齿误差。因此,仅检验其中一项误差不足以评定齿轮传动平稳性精度。标准规定取其中任意两项组合起来检验,以便于较全面地控制影响该项精度的切齿工艺误差因素。     

直齿锥齿轮参数化三维建模方法

介绍了在AutoCAD 环境下,用Autolisp 语言编程在计算机上实现直齿锥齿轮参数化三维建模的方法.程序设计是基于齿轮范成法切齿原理.使用该研究成果,只需加载Autolisp程序,输入模数、齿数、齿轮分度圆锥角等参数,便可以自动生成刀具和轮坯,齿轮的轮齿由刀具与轮坯间的相对滚切而形成.程序中还设计了轴、孔及键槽等结构,最后生成按指定参数的标准直齿锥齿轮模型.     

Improvement of the oblique-incidence optical interferometric system to measure tooth flanks of involute helical gears

We put forward a plan of improving the oblique-incidence optical interferometric system applied in the measurement of tooth flanks of an involute spur gear in order to expand its capability to measure an involute helical gear. On the basis of the features of an involute helical tooth flank, we discuss how to realize the parallelism between the optical axis of the object arm of the optical system and the straight lines constructing the involute helical tooth flank. This parallelism helps the optical system produce an interference fringe pattern as clear as the one of an involute spur gear [Appl. Opt.49, 6409 (2010).]. A numerical simulation is then performed to examine the correctness of the improvement. During simulating, we unify the equation of difference tooth flanks by means of importing two parameters in relation to the left or right side of a tooth flank and the helical direction of teeth, respectively. Finally, the actual experiment is fulfilled through the real optical system built on an optical table. The simulation and experiment results verify the correctness and feasibility of the proposed improvement.     

Development of scanning measurement of tooth flankform of generated face mill hypoid gear pair with reference to the conjugate mating tooth flank form using 2 axes sensor

The three diamensional (3D) scanning measurement method of tooth flank form of generated face mill gear pair is proposed, which is based on the conjugate mating tooth flank form. In this method, deviation sensor is placed at the position which has certain offset from the gear axis and synchronized to the gear rotation. This method realizes the 3D tooth flank form measurement and multi points scanning measurement by using 2 axes sensors. Based upon this proposal of the measurement method, tooth flank form measuring machine was developed and the experimental measurements were carried out. It is confirmed that this method is capable of high speed and high resolution measurement of fine waviness and it has high repeatability. It is confirmed that the proposed method, is capable of 3D scanning tooth form measurement of generated face mill hypoid gear pairs with high repeatability at high speed.     

Topographic error analysis of a gear plunge shaving cutter finished by a cone grinding wheel

Abstract

Gear shaving is one of the most efficient and economical ways to finish gears roughed by hobbing or shaping. The theoretical pitch surface of a gear plunge‐shaving cutter is a hyperboloid with hollow tooth form. The tooth profile of a plunge shaving cutter is usually ground by a cone grinding wheel. In this paper, we propose a mathematical model to calculate the topographical error of the tooth surface of a ground plunge‐shaving cutter compared with the theoretical tooth surface that is conjugated with the work gear. The proposed mathematical model can be used to calculate the profile data of the cone grinding wheel and the corresponding machine setup at a predetermined operating pitch cylinder. The topographic error sensitivities of the plunge‐shaving cutter due to varied operating pitch cylinder, helix angle, and grind wheel data are discussed based on the proposed mathematical model. This paper provides approximate guidance for choosing the proper operation cylinder, the helix angle, and the geometrical data of the cone grinding wheel for the finishing or resharpening of the plunge shaving cutter.     

Effect of applied voltage and electrolyte parameters on pitch,runout, flank topology,and finishing productivity of the straight bevel gears in PECH process

This paper describes improvements in the considered parameters of micro-geometry: flank surface topology and finishing productivity of 20MnCr5 alloy steel straight bevel gears through their finishing by pulsed electrochemical honing (PECH) process. Effects of three most important parameters of PECH process, namely applied voltage, electrolyte composition, and electrolyte concentration were investigated to identify their optimum values. Pre-identified values of other PECH parameters and an aqueous mixture of NaCl and NaNO₃ as an electrolyte were used in the present work. Errors in pitch (i.e., single pitch error, adjacent pitch error, and cumulative pitch error) and runout were used to evaluate micro-geometry of the straight bevel gears while volumetric material removal rate was used to judge the finishing productivity of the PECH process. Topology of the gear tooth flank surface and microstructure of the best-finished bevel gears were also studied. The results revealed considerable improvements in the micro-geometry, flank surface topology, and microstructure of the bevel gears finished by PECH. Applied voltage of 8?V, electrolyte composition of 75?wt.% NaCl?+?25?wt.% NaNO_3, and electrolyte concentration of 7.5?wt.% were identified as the optimum values to achieve simultaneous improvement in all the considered responses.     

渐开线锥形齿轮精密测量原理及方法

渐开线锥形齿轮由于同时存在锥度和螺旋角 ,使得其固定弦齿厚无法精确测量 ,也没有公法线。针对锥形齿轮的齿形特点 ,提出了一种利用钢球同时测量齿轮大、小端外点跨距的新方法 ,并推导了理论计算公式 ,从而实现了锥形齿轮在磨削等精加工过程中 ,其齿厚和锥度误差的在线精确测量。该方法经大量实际应用 ,证明了理论分析正确 ,测量方法可行     

Contact Pattern Analysis: Simulation of a Laser-Assisted Thermographic Approach

The contact pattern, defined as the area where gear teeth come into contact during their meshing, is a crucial quality feature of gears. If the size and location of the contact pattern are wrong, the gear meshing properties can be significantly affected (e.g., lifetime, noise). Despite several disadvantages, the so-called “paste method” is established as a method to analyse contact patterns. Here, a new measuring approach is examined using the Finite Elements Method (FEM). It is based on the heating-up of one tooth flank with a powerful laser, a subsequent partial transfer of the heat to a meshing tooth of the second gear wheel and finally capturing the heat distribution on that flank as an infrared image shortly afterwards. The thermal image should correspond to the contact pattern of that individual combination of teeth. A numerical analysis shows that at medium- and large-sized gears the achievable temperature increase will be high enough to be detected with modern infrared cameras.     

Two-stage optimum design of the dual-lead worm

The dual-lead worm and worm gear drive is a convenient anti-backlash mechanism. It can be used in precision machine tools and indexing tables. The objective is to minimize the frictional force between the worm and the gear. The constraints include the worm geometry, stresses, displacements and the natural frequency of the worm. To avoid a difficult 3-D shape optimization problem, a two-stage optimization method is introduced in this paper. The first stage optimization uses an approximate worm model. The threads of the worm are approximated by plate elements in this stage. The design variables are pitch diameter of the worm, the module of the gear and the difference of the left and the right modules. The second stage optimization uses a true 3-D solid model with continuous spiral threads to determine the optimum shape of worm threads. Examples show the approach is feasible and efficient.     

三维环境下高阶椭圆齿轮副的运动仿真

依据非圆齿轮传动特性,确定啮合齿轮在非圆节曲线上的位置及传动关系式,给出了非圆齿轮三维建模设计方法。利用Visual Basic语言对三维软件Solid Edge进行二次开发,实现了三维环境下椭圆齿轮参数化设计及运动仿真,能直观的观察到齿轮副的啮合状况。系统运行效果良好,为非圆齿轮传动三维设计提供了一种方法。     

Improving spur gear microgeometry and surface finish by AFF process

This paper describes improving microgeometry and surface finish of spur gears by abrasive flow finishing (AFF) by experimentally identifying optimum values of finishing time and AFF medium viscosity. An experimental apparatus was developed for gear finishing by AFF using a medium of silicon carbide as abrasives, silly putty and silicone oil as blending agents. A special fixture was developed comprising of two metalon cylindrical disks having circumferential holes for back and forth movements of AFF medium between two adjacent flanks of 20MnCr5 alloy steel spur gear teeth. Twenty experiments were conducted varying AFF medium viscosity at four levels and finishing time at five levels to study their influence on error reduction in total profile, total lead, total pitch, runout, and average surface roughness. Results showed considerable reduction in the microgeometry deviation and surface roughness with AFF medium viscosity increase and existence of optimum finishing time for attaining maximum improvement in microgeometry and surface finish. Consequently, 25?min and 135?kPa.?s were identified as optimum values and corresponding gear’s microgeometry and microstructure were studied. It revealed that AFF-finished gear flank surfaces are free from cracks, cutter marks, thermal distortions. This proves AFF as economical and productive alternative for gear finishing.