专家主轴设计系统英文翻译.docx

1、专家主轴设计系统英文翻译英文翻译英文原文 Expert spindle design systemAbstracThis paper presents an expert spindle design system strategy which is based on the efficient utilization of past design experience, the laws of machine design, dynamics and metal cutting mechanics. The configuration of the spindle is decided fr

2、om the specifications of the workpiece material, desired cutting conditions, and most common tools used on the machine tool. The spindle drive mechanism, drive motor, bearing types, and spindle shaft dimensions are selected based on the target applications. The paper provides a set of fuzzy design r

3、ules, which lead to an interactive and automatic design of spindle drive configurations. The structural dynamics of the spindle are automatically optimized by distributing the bearings along the spindle shaft. The proposed strategy is to iteratively predict the Frequency Response Function (FRF) of t

4、he spindle at the tool tip using the Finite Element Method (FEM) based on the Timoshenko beam theory. The predicted FRF of the spindle is integrated to the chatter vibration stability law, which indicates whether the design would lead to chatter vibration free cutting operation at the desired speed

5、and depth of cut for different flutes of cutters. The arrangement of bearings is optimized using the Sequential Quadratic Programming (SQP) method.Keywords: Spindle design; Expert system; Chatter vibration; Finite element method; Optimization1. IntroductionThe spindle is the main mechanical componen

6、t in machining centers. The spindle shaft rotates at different speeds and holds a cutter, which machines a material attached to the machine tool table. The static and dynamic stiffness of the spindle directly affect the machining productivity and finish quality of the workpieces. The structural prop

7、erties of the spindle depend on the dimensions of the shaft, motor, tool holder, bearings, and the design configuration of the overall spindle assembly.This research considers spindle component selection and configuration using the proposed expert system based on the digital knowledge base. The expe

8、rt system with fuzzy logic is implemented as the selection system.Eskicioglu et al. 1 developed a rule-based algorithm for the selection of spindle bearing arrangement using PRO-LOG, which is a programming language for expert systems. The bearing arrangements are determined by the cutting operation

9、type, and the required cutting force and life of bearings. Wong and Atkinson 2 demonstrated a knowledge cell approach for diverse designs. They divided the knowledge cell into four parts; the Function, Selection, Graphics, and Logic cells.For design optimization of spindles, Yang 3 conducted static

10、stiffness to optimize a bearing span using two bearings, and described the methods used to solve the multi-bearing spans optimization method. Taylor et al. 4 developed a program which optimizes the spindle shaft diameters to minimize the static deflection with a constrained shaft mass. The Downhill

11、Simplex Method is used to find the optimumvalue. Lee and Choi 5 conducted an optimization design in which they minimized the weight of the rotor-bearing system with the augmented Lagrange multiplier method. Chen et al. 6 and Nataraj and Ashrafiuon 7 demonstrated the optimization results to minimize

12、the forces transmitted by the bearings to the supports. Wang and Chang 8 simulated a spindle-bearing system with a finite element model anddepending on the machining application. In addition, most of them optimize design parameters, such as shaft diameter, bearing span, and bearing preload, to minim

13、ize the static deflection. This paper considers more than two bearings in the spindle model and takes into account the chatter stability that is totally related to the dynamic properties of the spindle.The overall expert spindle design system is outlined in Fig. 1. The design of the spindle with opt

14、imized bearing spacing is automated using the requirements set by the machining application, expert spindle design rules, cutting mechanics, structural dynamics and chatter stability of milling process.2. Expert system for spindle design The expert system for spindle design is introduced here to fac

15、ilitate the design process using past experience and knowledge.The expert system combined with the fuzzy logic is used as the selection system of components for the spindle design in order to handle uncertainties in the design process as illustrated in Fig. 2. The required input data for the spindle

16、 design, such as the cutting torque and power, are computed using the laws of cutting mechanics, as described in 11. The input data is entered into the fuzzy inference system, which is established by design experts, and is fuzzified using membership functions. The Mamdani method is used as the infer

17、ence system. The fuzzified values are applied to the fuzzy rules and aggregated using the maximum method. The result of the aggregation is defuzzified using the centroid method,and a defuzzified number is obtained. The simple defuzzified number is applied to the selection rule forthe spindle compone

18、nts. An external database, which includes material cutting coefficients, is connected to the fuzzy inference system, which users can access. The supervising engineer, who is permitted to maintain this expert system, can modify the membership function and database when the tendency of the fuzzy terms

19、, such as high, middle, and low changes as the technology evolves. In this article, transmission and lubrication types are determined using the expert system with fuzzy logic3. Optimization of bearing locations In order to apply the optimization to the spindle design, objective and design variables

20、are established. Chatter vibration is an important issue for machine tools since it may lead to spindle, cutter and part damages.There are significant number of parameters in a typical spindle design process, such as the dimensions of the spindle shaft, housing, and collars. However, the most effect

21、ive design parameters need to be selected to optimize the spindle design in practice. There are numerous constraints on the geometric design of spindle parts, and design dimensions which are usually coupled with each other. For example, if the diameter of the spindle shaft changes, the bore diameter

22、 of the housing also has to be changed, where more parameters need to be taken into account which may lead to a convergence problem in optimization algorithm. Since the objective function is highly non-linear, the Sequential Quadratic Programming (SQP) method is used in the optimization of the spind

23、le design.4. Application of the expert spindle design system The proposed system is demonstrated against a commercially existing machine tool (Mori Seiki SH-403) as shown in Fig. 14 for comparison. The main spindle specifications of SH-403 are shown in 17. The spindle has a motorized transmission wi

24、th oilair type lubrication with four bearings at the front and one at the rear. The maximum spindle speed is 20,000 rpm and the power and torque properties of the spindle motor are set from the data shown in 17. It is assumed that the user wishes to use the machine predominantly in cutting aircraft

25、parts made from Al7075-T6 with a four-fluted end mill with a desireddepth of cut of 3 mm and 15,000 rpm spindle speed. The most common cutting conditions are listed in Table 4. In order to select the transmission type from either the direct coupling type or the motorized type, Spindle Speed, High Dy

26、namic Stiffness vs. Low Balancing Vibration, Low Thermal Effect vs. Small Noise, and Low Replacement Operation Cost vs. Low Replacement Parts Cost need to be input. The spindle speed is automatically set from the maximum motor speed. In this case, the numbers are assumed from the concepts of the mac

27、hine written in the SH-403 catalog 17. The fuzzy weight numbers are setas 3, 8, and 4, respectively. Similarly, the fuzzy weight of the lubrication system is set.Table 5 shows the results of the spindle components selection. The Expert Spindle Design System selected the proper transmission and lubri

28、cation type.Table 6 shows the list of agreements between the actual design and the design that uses this expert system. The results attained via the expert system match those of the actual design in all five cases. Therefore, the proper spindle components can be selected with the proposed expert sys

29、tem, that is, the rule base and the membership functions of this system are defined properly.5. Conclusions This paper presents an Expert Spindle Design system for machine tool engineers. It proposes an alternative method to the present design practice, which is based on the past experience of indiv

30、idual designers, while attempting to eliminate costly trials by using the laws of machine design, solid mechanics, and metal cutting dynamics in an integrated fashion.The design configurations and membership functions are stored in a knowledge base using sets of design rules based on the past experi

31、ence and laws of cutting mechanics. Fuzzy logic is used as an inference engine in the proposed expert system. The fuzzy logic can deal with design uncertainties such as high, medium and low speeds or large/small torque required from the spindles where the exact numerical valuesare difficult to set r

32、igidly by the designers. The membership functions can be updated by the designers as the rules change due to technological advances in industry. The expert system leads to automatic generation of spindle configuration which includes drive shaft, motor type and size, transmission mechanism between the motor and shaft, and tool holder style.While the configuration and sub-components of the spindle are based on the torque, power, and speedrequirements from the machine tool, the exact locations of the bearings must be determined based on the chatter vibration stability of the spin