外文翻譯--三維微細(xì)超聲波加工研究（英文）

1、Z. Y. Yu e-mail: zyu@unlserve.unl.eduK. P. RajurkarA. TandonDepartment of Industrial revised September 2, 2004. Associate Editor: K. Dohda.Journal of Manufacturing Science and Engineering NOVEMBER 2004, Vol. 126 Õ

2、727enlarges the working area and more abrasive grains get involved in the material removal. The tool is also impacted by the abrasive grain, which causes the local deformation at the tool working area, followed by the cr

3、ack generation and material removal from the tool, leading to the tool wear. When the static load increases, the force acting on the tool increases, resulting in the increase of the tool wear as shown in Figs. 6 and 7. T

4、he generated cracks at the sharp-edge portion of a tool lead to tool fracture at the edge por- tion more easily than the center part of the tool. The proportion of the wear on the edge part in a smaller size tool is high

5、er than a large size tool. Therefore, the tool wear increases with the de- crease in tool size as shown in Figs. 6 and 7. It is observed that the gap decreases with the increase of static load ?Fig. 8?. The static load m

6、ay also suppress the lateral vibration of the tool when the static load increases. The above-mentioned experimental results indicate the extent of tool wear during micro-USM. When a 3D microshape is ma- chined, a tool wi

7、th microfeatures is needed to generate corre- sponding microfeatures. However, the preparation of a complex shaped microtool is a difficult task. Additionally, it is necessary to fabricate several complex shaped microtoo

8、ls to realize the accu-racy requirements of a design part because of the tool wear during machining ?20,21?. The use of multiple tools leads to tool align- ment problems. Therefore, it is difficult and uneconomical to fa

9、b- ricate and use multiple microtools. To solve these problems, a simple shaped tool, such as a cylinder or square, can be used to move along a designed tool path to generate 3D microshapes. The Wire Electrical Discharge

10、 Grinding ?WEDG? method is used to obtain simple shaped tools with various cross sections ?22?. A high tool wear occurring during machining prohibits the use of a single simple-shaped tool traveling along the CNC generat

11、ed path to machine complex 3D microcavities. Therefore, an approach of integrating the Uniform Wear Method with CAD/CAM software, which compensates tool wear and generates desired tool paths, is used in the following att

12、empt to generate 3D microcavities by USM. This approach has been successfully demonstrated for mi- cro EDM ?23,24?.3D Microcavities by USMTo generate complex 3D cavities with desired accuracy, it is necessary to compensa

13、te the tool wear and generate the tool path accordingly. An introduction to the Uniform Wear Method and its integration with a commercial CAD/CAM software is presented below ?from ?23,24??.Uniform Wear Method. The static

14、 load used to remove ma- terial from workpiece also causes wear of the microtool, resulting in local deformation and cracks on the microtool surface. To gen- erate accurate 3D microshapes it is necessary to compensate th

15、e tool wear in micro-USM. The basic principle of Uniform Wear Method is that under certain conditions, the shape of the tool is regained due to the tool wear after machining one layer. Thus, it may become shorter in leng

16、th but is able to regain the shape. To enhance this phenomenon, the tool path design must include fol- lowing rules.Layer-by-Layer Machining. The 3D microshapes are ma- chined layer-by-layer in the z-axis using simple-sh

17、aped tools. With a small tool feed to each layer, the shape of tool tip can easily be recovered after one layer machining without a deterio- rating effect on the machining surface.To-and-From Scanning. In one layer machi

18、ning, the machined surface inclines from the start point of tool paths to the end point of tool paths because the tool length becomes shorter due to the wear in machining. Reversing the tool paths, i.e., to-and-from scan

19、ning, is helpful in reducing the inclination of generated sur- face. This can be verified using the tool wear model. To further improve the machining accuracy, the cutting angle, i.e., the direc- tion of main paths is al

20、so changed.Tool Paths Overlapping. The edges and corners of a tool tip are worn more easily than the center part under the impact of ultrasonic vibration. The rounded edges and corners will be re- flected on the machined

21、 surface when the tool moves along theFig. 5 MRR versus average static loadFig. 6 Tool wear length versus average static loadFig. 7 Tool wear ratio versus average static loadFig. 8 Gap versus average static loadJournal o