外文翻譯----設計并聯(lián)機床使用kinetostatic標準的表現(xiàn)

1、THE DESIGN OF PARALLEL KINEMATIC MACHINETOOLS USING KINETOSTATIC PERFORMANCECRITERIA1. INTRODUCTIONMost industrial machine tools have a serial kinematic architecture, which means thateach axis has to carry the following

2、one, including its actuators and joints. High SpeedMachining highlights some drawbacks of such architectures: heavy moving parts requirefrom the machine structure high stiffness to limit bending problems that lower thema

3、chine accuracy, and limit the dynamic performances of the feed axes.That is why PKMs attract more and more researchers and companies, because theyare claimed to offer several advantages over their serial counterparts, li

4、ke high structuralrigidity and high dynamic capacities. Indeed, the parallel kinematic arrangement of thelinks provides higher stiffness and lower moving masses that reduce inertia effects. Thus,PKMs have better dynamic

5、performances. However, the design of a parallel kinematicmachine tool (PKMT) is a hard task that requires further research studies before wideindustrial use can be expected.Many criteria need to be taken into account in

6、the design of a PKMT. We pay specialattention to the description of kinetostatic criteria that rely on the conditioning of theJacobian matrix of the mechanism. The organisation of this paper is as follows: nextsection in

7、troduces general remarks about PKMs, then is explained why PKMs can beinteresting alternative machine tool designs. Then are presented existing PKMTs. Anapplication to the design of a small-scale machine tool prototype d

8、eveloped at IRCCyNis presented at the end of this paper.2. ABOUT PARALLEL KINEMATIC MACHINES2.1. General RemarksThe first industrial application of PKMs was the Gough platform (Figure 1),designed in 1957 to test tyres1.

9、PKMs have then been used for many years in flightsimulators and robotic applications2 because of their low moving mass and high dynamicperformances. Since the development of high speed machining, PKMTs have becomeinteres

10、ting alternative machine tool designs3, 4.guide rail interior to cause it to scratch, the attrition or the corrosion phenomenon. (7) Stewart platform suits in the modular production Regarding the different machine scope,

11、 only need change the connecting rod length and the contact position, maintains also easily, does not need to carry on part's remaking and to adjust, only need the new organization parameter input. (8) transformation

12、 coordinate system is convenient Because does not have the entity coordinate system, the engine bed coordinate system and the work piece coordinate system transform depend on the software to complete completely, is conve

13、nient. When the Stewart platform applies in the engine bed and the robot, may reduce the static error (, because high rigidity), as well as dynamic error (because low inertia). But Stewart the platform inferiority lies i

14、n its working space to be small, and it has the singular point limit in the working space, but the serial operation platform, the controller meets time the singular point, accountant will figure out the actuation order w

15、hich the drive is unable to achieve to create the ning error, but the Stewart platform will lose the support partial directions in the strange position the strength or moment of force ability, will be unable to complete

16、the constant load object. Figure 2a. A bipod PKMFigure 2b. A biglide PKM2.2. SingularitiesThe singular configurations (also called singularities) of a PKM may appear insidethe workspace or at its boundaries. There are tw

17、o types of singularities5. A configurationwhere a finite tool velocity requires infinite joint rates is called a serial singularity. Aconfiguration where the tool cannot resist any effort and in turn, becomes uncontrolla