Experimental Research on the Surface Quality of Milling Contour Bevel Gears

Contour bevel gears have the advantages of high coincidence,low noise and large bearing capacity,which are widely used in automobile manufacturing,shipbuilding and construction machinery.However,when the surface quality is poor,the effective contact area between the gear mating surfaces decreases,affecting the stability of the fit and thus the transmission accuracy,so it is of great significance to optimize the surface quality of the contour bevel gear.This paper firstly analyzes the formation process of machined surface roughness of contour bevel gears on the basis of generating machining method,and dry milling experiments of contour bevel gears are conducted to analyze the effects of cutting speed and feed rate on the machined surface roughness and surface topography of the workpiece.Then,the surface defects on the machined surface of the workpiece are studied by SEM,and the causes of the surface defects are analyzed by EDS.After that,XRD is used to compare the microscopic grains of the machined surface and the substrate material for diffraction peak analysis,and the effect of cutting parameters on the microhardness of the workpiece machined surface is investigated by work hardening experiment.The research results are of great significance for improving the machining accuracy of contour bevel gears,reducing friction losses and improving transmission efficiency.

Design and Experimental Research on Seedling Pick-Up Mechanism of Planetary Gear Train with Combined Non-circular Gear Transmission

Currently, transplanting mechanisms for dryland plug seedlings in China are mainly semiautomatic and have low efficiency. The rotary seedling pick-up mechanism with a planetary gear train for non-uniform intermittent transmission, and a concave and convex locking arc device, has a large rigid impact. To solve these problems, according to the design requirements for a dryland plug seedling transplanting mechanism, a rotary seedling pick-up mechanism of a planetary gear train with combined non-circular gear transmission of incomplete eccentric circular and noncircular gears was proposed. This has the characteristics of two-times greater fluctuation of the transmission ratio in a cycle, and can achieve a non-uniform continuous drive. Through analysis of the working principle of the seedling pick-up mechanism, its kinematics model was established. The human–computer interaction optimization method and self-developed computer-aided analysis and optimization software were used to obtain a set of parameters that satisfy the operation requirements of the seedling pick-up mechanism. According to the optimized parameters, the structure of the seedling pick-up mechanism was designed, a virtual prototype of the mechanism was created, and a physical prototype was manufactured. A virtual motion simulation of the mechanism was performed, high-speed photographic kinematics tests were conducted, and the kinematic properties of the physical prototype were investigated, whereby the correctness of the theoretical model and the optimized design of the mechanism were verified. Further, laboratory seedling pick-up tests were conducted. The success ratio of seedling pick-up was 93.8% when the seedling pick-up efficiency of the mechanism was 60 plants per minute per row, indicating that the mechanism has a high efficiency and success ratio for seedling pick-up and can be applied to a dryland plug seedling transplanter.

Kinematic Modeling and Characteristic Analysis of Eccentric Conjugate Non-circular Gear & Crank-Rocker & Gears Train Weft Insertion Mechanism

A novel weft insertion mechanism named eccentric conjugate non-circular gear & crank-rocker & gears train weft insertion mechanism was proposed in order to better meet the requirements of rapier loom's weft insertion mechanism as well as reduce the manufacturing difficulty. Meanwhile, based on the working principle of this mechanism, kinematical mathematic models of this mechanism were established and an aided analysis and simulation software was compiled. The influences of eccentricity ratio, deformation coefficient, and other important parameters on the kinematics characteristics of this mechanism were analyzed by using the software. A group of preferable parameters which could meet the requirements of weft insertion technology were obtained by means of human-computer interactive optimization method. The maximum velocity, maximum acceleration, and variation of acceleration of this mechanism are smaller than those of the conjugate cam weft insertion mechanism applied on TT96 rapier loom under the conditions of the same unilateral total stroke of rapier head and the same rotary speed of loom spindle; meanwhile the other demands of weaving technology can be met by this novel weft insertion mechanism.

Design and Experiment of Non-circular Combined Gear Train Beating-up Mechanism

The most important performance of a beating-up mechanism is that the dwelling time of the sley must ensure the completion of the weft insertion. To meet this requirement, a new non-circular combined gear train beating-up mechanism which is composed of two-stage planetary gear trains is proposed. The first-stage is a Fourier planetary gear train and the second-stage is a non-circular planetary gear train. For designing of this new mechanism, the ideal kinematic equations of the sley are constructed first. Then the kinematic model of the first-stage Fourier planetary gear train is established and the reverse solution for the pitch curves of the second-stage non-circular gears is deduced. With a computer-aided design program, the influences of several important parameters on the pitch curves of the second-stage non-circular gears are analyzed, and a set of preferable structural parameters are obtained. Finally, a test bed of this mechanism is developed and the experimental results show that this new beating-up mechanism can achieve the designed dwelling time, namely it can meet the requirements of beating-up process.

Research of contour error compensation control for X-C non-circular grinding in polar coordinates

In the X-C linkage grinding of non-circular parts,the computation and control method of contour error in polar coordinates platform is different with that in the XY coordinates platform.To solve this problem,the analysis of the definition and computation methods for contour error and track error in polar coordinates platform will be made.Through the relative lead-lag relation of the linkage axes in the grinding process,the range of the estimation contour error is narrowed and a contour error calculation model is constructed.Then the contour compensation controllers along contour error direction and trajectory tracking error direction are designed respectively,and the error compensation decoupling matrix of the X-C linkage axes is given as well.In the end of this paper,we take the machining of the cylinder contour in Wankel rotary piston engine as an example.A simulation experiment of contour error compensation control based on relative lead-lag quantity is made.The result shows that the designed contour compensation controller can increase the contour machining accuracy effectively.

Calculating method of contact stress for non-circular gears

According to Hertz theory, the difference of contact stress for non-circular gears and equivalent gears is compared in the paper, a calculating method of contact stress for non-circular gears by using equivalent gears is researched, and computing formulas of power and rotation speed for equivalent gears are deduced. A numerical simulation of contact stress for non-circular gears has also been conducted based on the finite element method. By the comparison of fitting curves, the feasibility of using equivalent gears instead of non-circular gears to calculate the contact stress is testified.

Research on Design Method of Non-Circular Gear Pair with Double Generating Angles

In order to enhance the bearing capacity of non-circular gear pair, the non-circular gear pair with double generating angles is proposed based on the design idea of unsymmetrical gear with double pressure angles. The tooth profile is designed by generating cutting theory, the pure rolling mathematic model that the center line of unsymmetrical rack roll along non-circular pitch curve is built, the digital model of non-circular gear with double generating angles is created through the second development method of CAD software, and then the drive characteristic and tooth strength are analyzed. The results show that the design method for double generating angles non-circular gear proposed in this paper is feasible, which is significant to improve the bearing capacity of non-circular gear pair.

修形斜齿轮成形磨削中齿廓精度补偿方法

建立了斜齿轮齿廓修形的坐标方程与成形磨削砂轮修整的几何算法,优化出齿廓修形后的砂轮截面廓形;通过数值模拟分析,得到了机床位置误差与齿廓偏差之间的耦合关系;编制了成形磨削齿廓精度调整软件,计算出斜齿轮修形与之对应的成形砂轮廓形和齿廓精度调整参数。通过修形斜齿轮的成形磨削试验,验证了砂轮廓形修整的正确性和齿廓精度调整的有效性。

Automatic Scallion Seedling Feeding Mechanism with an Asymmetrical High-order Transmission Gear Train

The current automatic scallion-transplanting machine is a complicated mechanism composed of two linkage mechanisms and two band carriers.It delivers seedlings ine ciently because of the movement limitations of the linkage mechanism.This paper proposes a new high-order non-circular gear train for an automatic scallion-seedling feeding mechanism.The proposed gear train has an asymmetrical transmission ratio;i.e.,its transmission ratio varies.This allows the mechanism’s execution component to move in a long displacement and rotate in a large rotation angle.The long displacement enables the execution component to reach the designed working position,and the large rotation angle allows it to feed a scallion in the required pose.A mathematical model for calculating the asymmetrical transmission ratio was established according to the closure requirements and the full-cycle motion of the driven gear pitch curve.Then,the parameter-design model of the new seedling-feeding mechanism was established,based on precise pose points and trajectory-shape control points.Moreover,an aided-design program was developed to obtain the parameter-solution domain of the scallion-seedling feeding mechanism.The mechanism parameters,which met the seedling-feeding function,were optimized to determine the transmission ratio,using a program and a kinematic simulation.Finally,a prototype of the mechanism was produced,and a seedling-feeding experiment was carried out.One-thousand seedlings were tested at a rate of 100 seedlings per minute,and the statistical success rate was 93.4%.Thus,the automatic scallion-seedling feeding mechanism significantly improves the e ciency of automatically transplanting scallions.

Design and Machining of Combination Gear Cutter Hob

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Research on stepless transmission utilizing noncircular gears

In view of the lack of systemic analysis for stepless transmission using noncircular gears, two basic noncircular gear units, an addition unit adopting differential mechanism and a multiplication unit applying a fixed gear train, are proposed. Then, the design methods of the noncircular gear pair of each unit, transmission ratio relationship, rotation angle relationship and key parameters with specific physical meanings are studied. The adjusting properties, composing strategy and varying range of transmission ratio etc. are investigated in detail for each unit. Following this, several examples of using a noncircular gear pair in the units and their manipulation technique are introduced.

高速高精度电子齿轮箱自抗扰控制研究

针对展成法加工齿轮切削力呈周期性变化引起刀具与工件的相对位姿偏差,导致工件齿轮加工误差的问题,文章提出一种基于自抗扰控制(active disturbance rejection control,ADRC)的主从式电子齿轮箱(electronic gearbox,EGB)控制方法。首先,分析滚齿加工过程中机床各运动轴之间的联动关系,建立斜齿轮加工运动控制数学模型,确立主从式EGB结构模型;其次,建立EGB中各轴跟踪误差与工件齿轮齿廓偏差、齿距偏差和螺旋线偏差之间的数学关系,采用交叉耦合控制(cross-coupling control,CCC)补偿方式求解出各运动轴的补偿量,对从动轴进行补偿;然后,构建基于传统比例积分微分(proportional integral derivative,PID)控制和扩张状态观测器(extended state observer,ESO)的ADRC-EGB,评估EGB从动轴所受的干扰并进行补偿,提高其同步精度和鲁棒性。最后,在开放式实时半实物仿真平台开展滚齿加工运动模拟实验。结果表明该EGB控制结构相较于传统EGB具有更高的同步控制精度和抗干扰能力。

Reverse design and tests of vegetable plug seedling pick-up mechanism of planetary gear train with non-circular gears

In the previous research,the seedling pick-up mechanism of the planetary gear train with incomplete eccentric circular gear and non-circular gears for vegetable plug seedlings still has two shortcomings.One is that not enough seedling pick-up depth leads to a low success ratio of seedling pick-up at high rotation speeds,the other is that the smaller seedling pushing angle results in poor seedling pushing effect.Therefore,the reverse design of the seedling pick-up mechanism based on its motion trajectory was carried out.The local trajectory of seedling pick-up and seedling pushing sections was adjusted to obtain the theoretical motion trajectory of the seedling pick-up mechanism.The cubic non-uniform B-spline curve was used to fit the adjusted trajectory.A novel seedling pick-up mechanism of the planetary gear train with non-circular gears was proposed,including three combined non-circular gears,four non-circular gears,one planetary carrier,and two seedling pick-up arms.The reverse design model of the mechanism was established.The analysis and design software of the mechanism was developed to obtain the mechanism parameters meeting design requirements.The virtual prototype of the mechanism was established and its physical prototype was manufactured.Through the virtual motion simulation and high-speed photographic kinematics bench tests of the mechanism,the kinematic model and results of reverse design of the mechanism were verified,with the kinematic performances of the mechanism prototype studied.The seedling pick-up tests of the mechanism were conducted in the laboratory.The success ratios of seedling pick-up were 94.2%,95.6% and 90.2% while the seedling pick-up efficiencies of the mechanism were 60,80 and 100 plants per minute per row,respectively.Besides,the seedling pushing effect was improved mush because of the greater seedling pushing angle.The seedling pick-up mechanism through revise design is of high value to be applied in the practical vegetable plug seedling transplanters.

基于电子齿轮箱的内齿珩轮强力珩齿轮廓误差补偿控制研究

多轴控制系统的轮廓误差具有强耦合特点,由于是多轴联动产生的结果,仅提高单轴的跟踪精度不一定能降低轮廓误差。为降低珩齿多轴控制系统的齿面轮廓误差,进一步提高珩齿的加工精度,文章提出一种简单有效的补偿控制策略。分析珩齿机的机床结构,根据珩齿多轴电子齿轮箱(electronic gearbox,EGB)控制系统的数学模型推导出基于齿轮啮合原理和坐标变换的齿面轮廓误差数学模型,并设计出一种简单的齿面轮廓误差补偿控制器。仿真和实验结果表明,所提出的补偿控制策略对降低齿面轮廓误差有显著的效果。该文方法对提高珩齿实际加工精度具有一定的指导意义。

非圆齿轮的测绘设计方法研究

针对非圆齿轮副的节曲线及其齿形复杂性、多样化及难以进行测绘与加工的特点,提出了采用测量的方法获得非圆齿轮副齿数、中心距、全齿高、压力角及齿顶曲线的数值,并通过反复计算确定这对非圆齿轮副的模数、齿顶高系数及径向间隙系数值,从而得到一个非圆齿轮的节曲线,并采用共轭节曲线的设计方法,获得另一个非圆齿轮的节曲线.利用提出的方法,对两对实际应用的非圆齿轮副进行了测绘设计与加工,取得了很好的使用效果.

电子齿轮比对轮廓误差及加工效率影响的研究

电子齿轮比仅考虑了在尺寸、加工速度上实现目标值与实际值的匹配,而忽视了插补加速度与交流伺服系统实际最大加速度能力的匹配。当电子齿轮比调节为偏离1较多的数值时,会对数控机床的轮廓误差和加工效率产生较大的不利影响,提出电子齿轮比和插补加速度优化算法,以减小电子齿轮比对数控机床轮廓误差和加工效率的影响。实验结果证明该算法是可行的。

基于图像处理的微小塑料齿轮轮廓优化

通过计算机视觉系统的构成、图像预处理、图像分割和数字图像的像素连通性理论与技术的研究,提出微小塑料齿轮的二值图像噪声点去除及齿轮轮廓提取方法,用数学形态学方法提出轮廓的简化算法,并给出了关键技术的原理及实现方法。发现通过删除曲线上多余点,可以达到用最少的点来表示一条曲线的目的。实验结果表明,该优化轮廓的简化算法,可获得准确的齿形检测数据,能满足工程测量的实际需要。

对我国齿轮感应淬火技术的评述

感应加热淬火具有高效、节能、污染小及易于实现自动化等优点。作者叙述了齿轮感应淬火中存在的主要问题 ,介绍了国内外有关的研究情况 。

基于机器视觉的注塑齿轮缺陷检测系统研究

在对齿轮缺陷进行人工检测的过程中,存在检测效率低、人为因素影响大等诸多问题,为此,提出了一种基于机器视觉技术的水表齿轮缺陷检测方法。首先,提出了一种水表齿轮的视觉检测系统的总体方案,并据此构建了检测系统的三维模型;其次,采用中值滤波方式对采集到的图像进行了图像平滑处理,并运用Canny算子完成了对齿轮边缘轮廓的提取;然后,采用图像金字塔与形状匹配相结合的模板匹配算法,找到了齿轮边缘轮廓和模板的位置关系,利用放射变换算法将两者重心变换重合;最后,通过计算两者的Hausdorff距离,提取了模板和待检测齿轮外轮廓间的最大误差以判别次品;并通过搭建测试平台对实际生产的齿轮进行了测试实验,结合实验结果对齿轮缺陷检测系统进行了验证。研究结果表明:该齿轮缺陷检测系统能有效检测出齿轮存在的缺陷,且其误检率低于2%,漏检率低于1%,检测时间不超过40 ms,可满足齿轮缺陷的在线检测要求。

利用柱面坐标设计弧面分度凸轮的轮廓曲面

通过分析凸轮与从动件之间的空间几何关系 ,建立了弧面分度凸轮廓面的柱面坐标计算式和压力角公式 ,据此可准确计算弧面分度凸轮工作廓面上任意一点的三维坐标和压力角 ,为此种凸轮的三维设计提供了理论基础。给出了一个算例 。