Flexible RollScann-design of one-tooth-roll-master and simulations for data acquisition

The recent improvements in the design and production of gears are not matched by the improvements in the development of measuring techniques and evaluation standards which can, in short time, give precise information about the quality of the produced gear. The inspection of gears with tooth flank modifications is still conducted by measuring of the profile and flank lines, pitch and concentricity. Furthermore topographical measurement on the coordinate measuring machine is an expensive and lasting process. This paper presents the development of a new, flexible gear-measuring machine called RollScan, which can measure the entire gear topography in a few minutes and can be introduced directly into the production line. For this, a machine with four axes and the control, a new one tooth roll master and evaluation software is designed, which makes the machine flexible and enables a variety of gear measurements without any special mechanical adjustments. The investigations described in this paper were sponsored by InnoNet from BMWi (16IN0276).     

交错轴斜齿轮副接触迹的研究与应用

交错轴斜齿轮啮合原理广泛应用于齿轮加工及测量,其特点是齿轮副满足点啮合原理。接触迹是其廓面上瞬时啮合点的集合,它是交错轴斜齿轮点啮合本质属性的反映。以圆矢量函数和媒介齿条为工具,推导了接触迹方程讨论了接触迷的特性。揭示了基于点啮合原理的齿轮加工与测量的实质,并阐述了接触迹在齿轮加工与测量中的应用。     

Investigation of work hardening of flat-rolled helical-involute gears through grain-flow analysis, FE-modeling, and strain signature

Net-shape forming of gears is under investigation by a number of researchers. The proposed new methods would reduce waste through chip elimination. Flat rolling of external-precision involute-helical gears is discussed in the current paper. This method is expected to have the additional advantage of producing stronger gears. The work-hardening effect on the critical regions of gear is investigated through the use of three-dimensional DEFORM finite element models (FEM). The simulation models were calibrated against designed experiments with a specific gear design. Also, current production gears were compared with gears manufactured through the new process. Samples were destructively tested to obtain metallurgical data. Hardness maps and grain-flow photographs were produced for the two groups of gears. Validation of FE modeling has opened the way for optimization of gear-rolling process through virtual design of experiments (DEX). It would be possible to vary FEM inputs such as blank material, gear specification, or die geometry and study the predicted impact on gear tooth strength.     

基于PowerMill的弧齿锥齿轮在五轴数控机床上的加工研究

目前对于单件、小批量弧齿锥齿轮的加工,需要齿轮专用机床或数控弧齿锥齿轮铣齿机,该类机床存在加工对象窄、加工范围有限、单件生产成本高等局限性;对于一些特殊参数的不完全齿或应用在某些特殊场合的弧齿锥齿轮,无法在专用机床上加工。针对上述问题,提出在五轴数控机床上完成弧齿锥齿轮加工,指出了问题,并给出解决方案;实现了UG环境下弧齿锥齿轮的数字化建模,在Power Mill软件下生成弧齿锥齿轮的刀具路径且后置处理生成NC代码,并在VERICUT环境下进行仿真与效验,最后在五轴数控机床DMG_DMU50V上完成零件加工。经锥齿轮检查机检测,用五轴数控机床加工弧齿锥齿轮能满足设计要求,适合于单件或小批量生产。     

Geometric error measurement of spiral bevel gears using a virtual gear model for STEP-NC

Geometric error measurement is required to evaluate the grade of the manufactured gears. Due to the complexity of the spiral bevel gear, direct measurement with the physical part has been conducted in a very limited way. In this paper, we present an indirect measurement based on the virtual gears model (VGM), obtained by NUBS fitting of the surface points measured by CMM (coordinate measuring machine). By comparing the VGM with CAD model (soft-master model), various errors such as tooth profile error and tooth trace error can be automatically measured. The developed method is simple and robust without requiring a special measuring device, and hence it can be applied for the industrial practice as a means for measuring the tooth profile and tooth trace errors which cannot be measured by the conventional method. Further, the model-based method can be incorporated on the advanced CNC controller based on the new CAM–CNC interface scheme of STEP-NC [STEP (standard for transfer and exchange of product model data) based data model for CAM and CNC interface] as an on-line inspection module. Algorithmic details together with experimental validation results are given.     

Use of damping materials for increasing the quality and service properties of parts

Conclusion Type 04Kh11Yu chromium-aluminum steels are promising high-damping materials. They contain readily available alloy elements and are more corrosion- and scale-resistant than such high-damping alloys as magnesium and manganese-copper alloys and cast irons. In addition, they are more easily melted and hot worked by pressure than magnesium and manganese-copper alloys. Heat treatment of chromium-aluminum steels for high damping is simple.Broader use in industry of increased damping capacity type 120S2YuD graphitic steels is desirable. They are hardened significantly by heat treatment, are relatively inexpensive, and have recommended themselves positively during experimental production tests on reduction of the noise of mechanisms with gear drives. The use of them in place of 40Kh and 30KhGSA steels causes a reduction in noise of mechanisms with gear drives of 6 db. In addition, the wear resistance of the gears increases.Kirov Polytechnic Institute. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 12, pp. 3–4, December, 1987.     

上传主动锥齿轮断裂分析

发动机返厂检查发现上传主动锥齿轮的一个轮齿发生断裂。通过对断裂齿轮进行断口宏微观分析、金相组织和硬度检查,分析认为锥齿轮的断裂性质为弯曲疲劳,疲劳断裂的原因是齿根弯曲应力过大。对齿轮齿厚、齿根圆角进行测量,对齿根圆角过渡情况进行检查,并运用有限元分析方法对锥齿轮断齿受力进行模拟分析。结果表明:齿根弯曲应力过大是因为齿厚超差导致齿轮啮合位置偏离,同时齿轮在加工过程中齿根存在加工接刀尖边导致齿根应力分布改变,出现应力集中。后续采取改进齿轮的加工工艺及加强对齿轮的制造质量控制等措施,避免该类故障再次发生。     

齿轮精密锻造技术的发展

研究和试验了圆柱直齿轮、圆柱斜齿轮和同步齿轮等 3种汽车用齿轮。制造工艺采用温锻加冷处理 ,用有限元模拟来分析锻造过程和设计模具 ,从而保证齿轮的精度。经过 3年的研究 ,已掌握其基本技术 ,下一步将进行工厂现场试验     

大齿轮齿向误差在机测量技术

从大齿轮及其齿向测量的特殊性入手,分析了大齿轮齿向在机测量的关键问题;创新提出了利用高精度水平仪调整仪器测量基准的方法和对测量数据进行系统误差补偿的思想;研究了大齿轮齿向在机测量技术和方法。     

齿轮的热处理畸变与控制

通过大量的试验研究和长期的生产实践，探讨了齿轮在高频淬火和渗碳淬火后的畸变规律，并提出了相应的减少畸变的措施，生产实践表明，采取这些措施后，能有效地控制齿轮畸变，解决生产中的关键问题。     

等高齿对数螺旋锥齿轮加工仿真

对数螺旋线作为齿向线的螺旋锥齿轮称之为对数螺旋锥齿轮,对数螺旋锥齿轮按照齿高分有渐缩齿与等高齿两类,它具有沿齿向线方向螺旋角处处相等这一显著优点。由于等高齿螺旋锥齿轮具有传动平稳性高、运转噪音低等优点,等高齿螺旋锥齿轮在我国应用越来越广泛,尤其在重型卡车中。但与一般的螺旋锥齿轮相比,其空间啮合理论较为复杂。通过研究基于UG的CAM功能,创建刀具、几何体以及程序,计算等高齿对数螺旋锥齿轮的刀具轨迹仿真,为实现齿轮的数控加工奠定基础。     

弧齿锥齿轮三维参数化设计

介绍了利用Pro／E复杂曲面造型及Program开发功能实现弧齿锥齿轮三维参数化设计的基本思想、方法和步骤，为弧肯锥齿轮啮合、传动、分析、加工等方面的深入研究提供了十分有用的工具和手段。     

A novel hob cutter design for the manufacture of spur-typed cutters

Spur-typed cutters with multiple cutting angles are important tools frequently used in the manufacture of many machine elements. Due to their complex geometry, the production of these cutters involves milling and several grinding processes. Such a complex manufacturing process, coupled with the need for expensive manufacturing tools, makes the cutters costly.Undercutting is a phenomenon that causes weakness at the root of a gear. Engineers use shifted gears, modified tooth profiles, or changes in the pressure angle to overcome undercutting in gears. However, in this paper, by utilizing the undercutting phenomenon, a novel design of straight-sided hob cutter with multiple pressure angles is proposed for the manufacture of spur-typed cutters. With the simultaneous application of multiple pressure angles, this tool design concept significantly simplifies the manufacturing process. The effects of cutting angles, the degree of undercutting, and the width of the top land of the cutter are studied. The concepts and results proposed in this paper are beneficial as design guidance for tool designers and manufacturers.     

Sculptured surface machining of spiral bevel gears with CNC milling

Gears are crucial components for modern precision machinery as a means for the power transmission mechanism. Due to their complexity and unique characteristics, gears have been designed and manufactured by a special type of machine tools, such as gear hobbing and shaping machines. In this paper, we attempt to manufacture the spiral bevel gear (SBG: the most complex type among the gear products) by a three-axis CNC milling machine interfaced with a rotary table. This consists of (a) geometric modeling of the spiral bevel gears, (b) process planning for NC machining, (c) a tool path planning and execution algorithm for both 4-axis and 3/4-axis (three out of four axes) controls. Experimental cuts were made to ascertain the validity and effectiveness of the presented method with a CNC milling machine controlled by the 3/4-axis control mode.     

Gear tooth stiffness reduction measurement using modal analysis and its use in wear fault severity assessment of spur gears

Due to excessive service load, inappropriate operating conditions or simply end of life fatigue, damage can occur in gears. When a fault, either distributed or localised, is incurred by gears, the stiffness and consequently vibration characteristics of the damaged tooth will change. A possible non-destructive technique for damage detection and severity assessment can be derived from vibration analysis. This paper presents the use of vibration analysis in the detection, quantification, and advancement monitoring of damage incurred by spur gear teeth. The stiffness of a single spur gear tooth is analysed theoretically, and due to the difficulties in measuring the gear tooth stiffness, an experimental procedure based on the modal analysis is developed to assess the severity of the gear tooth damage. A pair of spur gears was tested under accelerated wear conditions, and conventional time and frequency domain techniques are applied to the gear vibrations to indicate the presence and progression of the wear. The developed modal stiffness assessment technique is then used to quantify the resulting wear damage to the spur gear teeth.     

两端面具有凸块的齿轮锻件温挤成形工艺设计

以某90型摩托车变速箱中的花键主动齿轮锻件为例,依据温挤成形技术原理,对复杂形状齿轮锻件进行了锻件分析和温挤成形工艺分析,阐述了复杂形状齿轮锻件温挤成形工艺设计中的难点与关键点,并结合生产实际,制定了适合生产实际的温挤成形工艺。设计了一套经济实用的温挤成形模具,同时介绍了模具结构和工件原理。经批量生产试制证明,该温挤成形工艺生产的齿轮锻件质量稳定、凸块饱满,且模具结构合理、通用性强、生产效率高。     

Tooth profile design for the manufacture of helical gear sets with small numbers of teeth

Based on gear theory and generating mechanism, this investigation presents a complete mathematical model of a helical gear set with small number of teeth. The unavoidable tooth-profile undercutting of the gears with small number of teeth is examined by using the developed mathematical model and the conventional method of tooth-profile shifting. Furthermore, an alternative method for lessening the tooth-profile undercutting is also presented by considering a modification of the basic fillet geometry using a modified rack cutter. A third method, combining the aforementioned two methods for the design of helical gears with small number of teeth is also proposed to yield a gear set without tooth undercutting. The mating gear with profile shifting is generated using the pinion as a shaper. The tip fillet and root fillet are modified and a clearance between the pinion and the mating gear is also included in the design. Analysis results indicate that the change of distance between the centers of gear set depends only on gear shifting. Moreover, computer graphs are demonstrated the profile-shifted and the proposed modified gear tooth profiles.     

Method for removing burrs and pits from small gears using a gear-shaped tool composed of glass-fiber-reinforced plastic

Gear characteristics are strongly dependent on the quality of the tooth edge of the gears. Therefore, methods for removing defects such as burrs and pits of gears are very important. Burrs and pits are particularly difficult to remove from small gears due to the small dimensions of the tooth grooves. In addition, the equipment for the removal process should be simple and low in cost. In the present study, a method using a gear-shaped tool made from glass-fiber-reinforced plastic (GFRP) is developed for removing burrs and pits from small gears. A manufacturing method for the GFRP gear-shaped tool is proposed and it was confirmed that a conventional hobbing machine and a carbide hob can easily manufacture such a tool without defects. The ability of the proposed tool to remove burrs and pits is evaluated experimentally and the results demonstrate that the burrs and pits of a work gear can be effectively removed by using the proposed tool with simple equipment based on a lathe. This tool was then applied to the mass production of gears, and it was confirmed that this tool has the durability to remove the burrs of 16,797 work gears.     

螺旋锥齿轮双锥辊辗压成形模具设计

介绍从动螺旋锥齿轮的生产现状及缺点,提出双锥辊辗压成形螺旋锥齿轮的工艺.以某齿轮为例,给出了辗压工艺、毛坯设计方法、模具结构及其特点.通过试验锻造出合格的锻件,验证该工艺切实可行,模具设计合理可靠.     

渗碳齿轮齿根喷丸强化研究现状与展望

弯曲疲劳是齿轮传动中的主要失效形式,严重影响了齿轮使用性能.喷丸强化工艺是齿轮常用的表面强化方法,对提升齿根抗弯曲疲劳性能效果显著.介绍了两种典型的喷丸强化方法(气动式喷丸和离心式喷丸),分别从应用范围、加工效率、喷射原理、表面完整性等方面对其进行了比较.为揭示喷丸强化机制,概述了喷丸工艺数值模拟与工艺参数优化方法,分析了喷丸对齿根表面完整性影响机制,并阐述了表面完整性参量之间的相互作用关系.同时,阐明了齿轮喷丸后的疲劳断裂机理,包括裂纹萌生与扩展机制.在此基础上,重点论述了受喷齿轮弯曲疲劳性能的影响因素,并提出了改善齿轮疲劳强度的措施.此外,简要探讨了齿轮喷丸后,疲劳强度提升幅度问题,并归纳了受喷齿轮弯曲疲劳建模方法.最后,对齿轮齿根喷丸强化工艺进行总结,并对其发展趋势进行了展望.