模切机工作台运动特征分析及实现

主要是通过对实际版台运行曲线的分析比较,根据版台的实际工作情况来确定版台的最佳运行曲线。然后通过对工作台的运动过程的曲线的求解来得出最理想的运动曲线,再对工作台的各工作段的进行运动长度及时间的分配来得出工作台速度和加速度的曲线图。再结合通过工作台运动过程求解得出的运动曲线,再对各个速度和加速度的曲线图进行比较分析来确定最佳的运动曲线。再对曲线进行分析,确定工作台运动曲线能否满足机架强度的要求。     

Prediction and compensation of motion accuracy in a linear motion bearing table

In the present research, a corrective machining algorithm is introduced to improve the motion accuracy of linear motion bearing tables. The algorithm commences with reverse analysis, in which the rail form error is estimated from the measured linear and angular motion errors. In the next step, the rail is remachined to reduce the estimated form error. Then, the motion errors are measured again, and the procedure is repeated until the measured errors are sufficiently small. A transfer function, which represents the bearing force variation of a bearing block with respect to the spatial frequency components of the rail form error, is used to describe the characteristics of the linear motion bearings. Computations are carried out via the Hertz contact theory. From the theoretical evaluation, it is evident that the magnitude of the normalized transfer function quantitatively represents the accuracy averaging effect at each spatial frequency and that motion errors are not affected by the preload and the stiffness of the bearings. It is also clear that the algorithm can be used to estimate the equivalent rail form error in terms of motion errors. As a practical application, the algorithm is utilized to improve the motion errors of an XY table with linear motion bearings. The experimental results show that the motion accuracy of a linear motion bearing table can be improved to about 1 μm of linear motion error and about 1-2 arcsec of angular motion error by applying the proposed algorithm.     

Compensation for five DOF motion errors of hydrostatic feed table by utilizing actively controlled capillaries

Five DOF motion errors of a hydrostatic bearing table driven by a coreless type linear motor were compensated by utilizing actively controlled capillaries in the present research. The motion errors of horizontal translation and yaw were compensated simultaneously with the two actively controlled capillaries, and those of vertical translation, pitch and roll were compensated simultaneously with the three actively controlled capillaries. The actively controlled capillaries were designed and their gains were adjusted by conducting micro step response tests. The five DOF motion errors were measured ultra-precisely by combining three measuring methods as follows. The yaw and pitch errors were measured with a laser interferometer, and the roll error was measured by the reversal method. Then, the translational motion errors in the horizontal and vertical directions were measured by the sequential two-point method, where influence of the angular motion errors on the translational measurement was compensated by utilizing the measured angular motion errors. By utilizing the developed capillaries and the combined measuring methods and by applying the iterative control, the motion errors of the horizontal translation, the vertical translation, the yaw, the pitch and the roll were compensated simultaneously and reduced significantly from 0.16 μm, 0.18 μm, 1.96 arcsec, 2.26 arcsec and 0.14 arcsec to 0.02 μm, 0.03 μm, 0.03 arcsec, 0.07 arcsec and 0.02 arcsec, respectively. The remaining motion errors were less than the measuring repeatabilities which were ±0.02 μm for the translational motion errors and ±0.05 arcsec for the angular motion errors. The results show that the present method is not only practical but also effective to realize the ultra-precision feed motion whose accuracy is equal to the currently reachable measuring accuracy.     

大型机床工作台的动态性能研究及结构优化

设计了用于大型落地镗铣床的新型工作台,利用ANSYS对工作台整体进行结构优化,根据可去除材料的分布云图,得到了工作台内部筋板的布置以及筋板上出砂孔的位置.对基本筋格单元进行变量的动态优化,研究了筋格结构参数对筋格固有频率的影响及筋格相关参数对工作台整体的影响,再次优化后得到理想的工作台筋格结构.优化后的工作台能减轻质量、提高刚性及动态性能.     

Experimental study and parameter design of electro-discharge diamond grinding

Electrical discharge diamond grinding (EDDG), which integrates diamond grinding and electro-discharge machining (EDM), is a new hybrid machining process for shaping electrically conductive very hard materials. The process employs synergetic interactive effect of electro-discharge action and abrasion action to increase machining performance. This paper presents an investigation on the experimental study and machining parameter design of electro-discharge diamond grinding (EDDG). The EDDG setup was designed and fabricated, and experiments were conducted on high speed steel (HSS) workpiece under varying current, pulse-ontime, duty factor and wheel speed. The settings of machining parameters were determined by using the Taguchi experimental design method. The level of the machining parameters on the MRR is determined by using analysis of variance (ANOVA). The optimum machining parameter combination was obtained by using the evaluated S/N ratio.     

轮胎动态实验台往复运动位移自动测控系统

往复运动位移的自动测控系统是轮胎动态实验台的核心部分，它直接影响实验台的性能。文中提出一种由磁致伸缩线性位移传感器、MAXl95A／D转换器和AT89C52单片机组成的往复位移自动测控系统。现场使用和实验表明，该系统的测量误差小于1mm，具有测量精高、可靠性好和环境适应性强等优点。     

Optimization of the film coating process for polymer blends by the grey-based Taguchi method

The purpose of this paper is to find the optimum conditions of the film coating process for polymer blends and the influence of major processing parameters on the morphological properties of the material surface has been discussed. The surface roughness is regarded as the target characteristic of the smaller-the-better system. In order to achieve the aim of the multiple-response process of robustness, the grey-based Taguchi method is proposed. Nine experimental trials based on the L₉(3⁴) orthogonal array are conducted to determine the optimum processing conditions, the significant factor levels, and the percent contributions together with the analysis of variance (ANOVA). Also, confirmation experiments are performed to verify that the experimental results are reproducible. Moreover, atomic force microscopy (AFM) can be carried out with 3D atomic resolution in air for the measurement and analysis of the precision surface .     

滚动直线导轨副运动精度研究

本文运用随机振动的数学模拟法,对滚动直线导轨副的运动精度进行了研究,其结论有助于滑块沟槽过渡曲线的优化。     

Bounds on the performance of analog-to-digital converter look-up table post-correction

Analog-to-digital converter additive post-correction using look-up tables is considered. The problem of successfully predicting the converter’s performance after correction is treated in particular. An accurate expression is provided that predicts the ADC performance after correction. The expression depends on differential non-linearity, random noise variance, and the numerical precision of the correction terms. The theory shows good agreement when compared with simulations and experimental converter data. The results are useful when designing systems involving ADCs and post-correction, since the performance parameters can be obtained with knowledge of a few ADC intrinsic parameters and the correction system resolution.     

Application of Taguchi-grey multi responses optimization on process parameters in electro erosion

Convention Taguchi method deals with only single response optimization problems. Since the electrical discharge machining process involved with many response parameters, Taguchi method alone cannot help to obtain optimal process parameters in such process. In the present work, an endeavor has been made to derive optimal combination of electrical process parameters in electro erosion process using grey relational analysis with Taguchi method. This multi response optimization of the electrical discharge machining process has been conducted with AISI 202 stainless steel with different tool electrodes such as copper, brass and tungsten carbide. Gap voltage, discharge current and duty factor have been used as electrical excitation parameters with different process levels. Taguchi L₂₇ orthogonal table has been assigned for conducting experiments with the consideration of interactions among the input electrical process parameters. Material removal rate, electrode wear rate and surface roughness have been selected as response parameters. From the experimental results, it has been found that the electrical conductivity of the tool electrode has the most influencing nature on the machining characteristics in EDM process. The optimal combination of the input process parameters has been obtained using Taguchi-grey relational analysis.     

Dynamic optimization algorithm of constrained motion

The constrained motion requires the determination of constraint force acting on unconstrained systems for satisfying given constraints. Most of the methods to decide the force depend on numerical approaches such that the Lagrange multiplier method, and the other methods need vector analysis or complicated intermediate process. In 1992, Udwadia and Kalaba presented the generalized inverse method to describe the constrained motion as well as to calculate the constraint force. The generalized inverse method has the advantages which do not require any linearization process for the control of nonlinear systems and can explicitly describe the motion of holonomically and/or nonholonomically constrained systems. In this paper, an explicit equation to describe the constrained motion is derived by minimizing the performance index, which is a function of constraint force vector, with respect to the constraint force. At this time, it is shown that the positive-definite weighting matrix in the performance index must be the inverse of mass matrix on the basis of the Gauss’s principle and the derived differential equation coincides with the generalized inverse method. The effectiveness of this method is illustrated by means of two numerical applications.     

多工位级进模具运动仿真技术研究与应用

多工位级进模具工序多,模具结构复杂,其设计难度大,开发周期长。借助UG运动分析模块对模具运动全过程进行仿真设计,分析了多工位级进模运动过程,建立了仿真实验并运行,研究并实现了全过程仿真的关键技术。将该技术应用于某公司汽车零部件级进模具设计,可模拟条料送进过程中模具各工位的工作情况,使设计人员即时对设计方案进行验证、修改、优化,对提高企业模具设计水平及效率,减少开发周期及成本起到了较好的效果。     

Modeling and optimization of Al/SiCp MMC machining using Taguchi approach

This paper presents the influence of process parameters like cutting speed, feed and depth of cut on flank wear (VBc) and surface roughness (Ra) in turning Al/SiCp metal matrix composites using uncoated tungsten carbide insert under dry environment. The experiments have been conducted based on Taguchi’s L₉ orthogonal array. Abrasion and adhesion are observed to be the principal wear mechanism from images of tool tip. No premature tool failure by chipping and fracturing was observed and machining was steady using carbide insert. Built-up-edge formation is noticed at low and higher cutting speed and at high feed combination and consequently surface quality affected adversely. The optimal parametric combination for flank wear and surface roughness are found to be v1–f1–d3 and v3–f1–d3 respectively and is greatly improved through Taguchi approach. Mathematical models for flank wear and surface roughness are found to be statistically significant.     

松散物料在水平圆振动干燥机中的运动分析

依据流体力学和振动学的基本原理,建立物料在水平圆振动干燥机中的运行方程,得出物料在单层孔板上运行周期及时间表达式.并通过该方程的电算方法得到物料运行任意位置所需时间,经实际验证模拟值与实测值吻合较好.     

铁路提速客车轴承的台架运转性能试验分析

通过台架试验的温升对比数据分析和分解检查,验证了铁路提速客车轴承设计的正确性,可完全满足我国铁路提速客车运用的需要,可以为装车试验做充分的准备。     

A study of the Taguchi optimization method for surface roughness in finish milling of mold surfaces

The objective of this paper is to develop a Taguchi optimization method for low surface roughness in terms of process parameters when milling the mold surfaces of 7075-T6 aluminum material. Considering the process parameters of feed, cutting speed, axial-radial depth of cut, and machining tolerance, a series of milling experiments were performed to measure the roughness data. A regression analysis was applied to determine the fitness of data used in the Taguchi optimization method using milling experiments based on a full factorial design. Taguchi orthogonal arrays, signal-to-noise (S/N) ratio, and analysis of variance (ANOVA) are used to find the optimal levels and the effect of the process parameters on surface roughness. A confirmation experiment with the optimal levels of process parameters was carried out in order to demonstrate the effectiveness of the Taguchi method. It can be concluded that Taguchi method is very suitable in solving the surface quality problem of mold surfaces.     

Design optimization for the performance enhancement of large scale thermosyphons

As a method to enhance performance of a low-tilt thermosyphon, a groove wick was recommended and individual performance limitations which includes the capillary, boiling, entrainment, viscous and sonic limits corresponding to the existing wick configuration, were first examined for different operating vapor temperatures using conventional steady-state techniques available in the literature. Second, using a computer model developed to predict the axial liquid pressure drop and the boiling limit heat flux, a parametric investigation was performed to determine an optimal configuration of groove wicks designed to improve the operational performance. Results of the present study showed that the heat transport capacity was significantly affected by wick geometry, such as groove angle, groove width and groove depth.     

Methodology of Taguchi optimization for multi-objective drilling problem to minimize burr size

Formation of exit burr on part edges during drilling has several undesirable features with regard to product quality and functionality. Hence it is essential to select optimum drilling process parameters to minimize burr size at the production stage. This paper presents the application of the Taguchi optimization method for simultaneous minimization of burr height and burr thickness influenced by cutting conditions and drill geometry. The Taguchi design approach to the multi-objective optimization problem is based on the introduction of a new concept of fitness function for each trial of orthogonal array. The fitness function is derived through mapping the objective functions of the drill optimization problem. In the present work, optimal values of cutting speed, feed, point angle and lip clearance angle are determined for selected drill diameter values to minimize burr height and burr thickness during drilling of AISI 316L stainless steel workpieces. The details of experimentation, analysis of means and analysis of variance are presented in the paper.     

一种基于指令向量表的软PLC系统实现方法

提出了一种基于指令向量表的嵌入式软PLC系统的实现方法。系统由开发系统和执行系统构成。开发系统所编辑的梯形图（LAD）、语句表（STL）形式的PLC程序将被转换生成为中间代码。执行系统建立一个指令向量表,按指令识别码储存中间代码指令函数的入口地址,使解释型软PLC系统取指后可以对中间代码的指令执行函数进行直接快速跳转,从而提高解释型软PLC的执行效率,保证了解释型软PLC执行系统的实时性,使解释型软PLC执行系统具有接近于编译型软PLC执行系统的执行速度。     

Multi-objective optimization of forming parameters for tube hydroforming process based on the Taguchi method

Tube hydroforming is an attractive manufacturing technology which is now widely used in many industries, especially the automobile industry. The purpose of this study is to develop a method to analyze the effects of the forming parameters on the quality of part formability and determine the optimal combination of the forming parameters for the process. The effects of the forming parameters on the tube hydroforming process are studied by finite element analysis and the Taguchi method. The Taguchi method is applied to design an orthogonal experimental array, and the virtual experiments are analyzed by the use of the finite element method (FEM). The predicted results are then analyzed by the use of the Taguchi method from which the effect of each parameter on the hydroformed tube is given. In this work, a free bulging tube hydroforming process is employed to find the optimal forming parameters combination for the highest bulge ratio and the lowest thinning ratio. A multi-objective optimization approach is proposed by simultaneously maximizing the bulge ratio and minimizing the thinning ratio. The optimization problem is solved by using a goal attainment method. An example is given to illustrate the practicality of this approach and ease of use by the designers and process engineers.