鈦合金端面銑削加工中的微量潤(rùn)滑技術(shù)研究.pdf

1、In metal cutting operations, cutting fluids used in order to elongate the tool life and to improve the product precision. Nowadays, the use of cutting fluids in machining operations has been questioned, because of proble

2、ms they may cause to the operators and machines. The minimization of fluids lead to many economical benefits by way of saving lubricant cost, workpiece/tool/machine cleaning cycle time, and problems of procurement, stora

3、ge, disposal and maintenance. Recently, titanium alloys have been widely applied in industry because of their superior mechanical properties, heat and corrosion resistance, this trend is more emphasized for the near

4、future. Titanium alloys, however, are regarded as extremely diffficult-to-machine. Tool wear progressing rapidly because of a high cutting temperature and strong adhesion between the tool and work material resulting from

5、 their low thermal conductivity and high chemical reactivity. Removal of heat from the cutting zone is commonly used to keep the rate of wear under control, and for this purpose a copious amount of fluid is flushed into

6、the cutting zone at low pressure from the back side of the chip to facilitate heat transfer from the cutting zone.However, this will entail serious techno-environmental and biological problems to operators' health. C

7、ompletely dry cutting lowers the required cutting force and power on the part of the machine tool as a result of increase in cutting temperature. However, achievable tool life and part finish often suffer under completel

8、y dry condition. Therefore, the permissible feed and depth of cut have to be restricted. Under these considerations,the concept of minimum quantity lubrication presents itself as a possible solution. Minimum quantity

9、 of lubrication (MQL) refers to the use of cutting fluids of only a minute amount typically of a flow rate of 50 to 500 ml/hour, which is an about three to four order of magnitude lower than the amount commonly used in f

10、lood cooling condition. In this research work, this cooling technique; which is the pulverization of minimum volume of soluble oil in a flow of compressed air, used while face mill of titanium alloys to study its cooling

11、 efficiency and compare the performance with other The first result of dry milling test presented that, dry cutting of titanium is very effective with respect to tool wears at low cutting speeds; this speed can be i

12、ncrease in discontinuous cutting. Flank wear is the dominant tool failure mode, the occurrence of this failure can be avoid by decrease the cutting speed, increase feed rate or by the correct selection of depth of cut.

13、 The second result is that, Although, large percentage increase in MQL flow rate results in only small percentage increase in heat transfer, but minimum quantity of lubrication seems to be an efficient cooling techniqu

14、e compares to others in tool behavior and workpiece quality, and due to the small amount of coolant in MQL cooling technique, it has no effect in the beginning of milling and starts to affect beneficially with the progre

15、ss of cutting time. The third result, minimum lubrication of 125 ml/h is the suitable flow rate for milling of titanium alloys by using PVD-coated inserts, it is environmentally safe, and compare with wet cooling, it

16、 presented good values of tool life even at high cutting speeds. The fourth result shown, feed rate is the most influential cutting parameter affecting the duration of tool life and the amount of volume removed. Para

17、meters improving these characteristics which, has no significant effect on the quality of surface roughness, can easy optimize by using Taguchi analysis method. The fifth result is that, the study of the behavior of

18、the shape, thickness and serrations in the edge of chips form during milling is very useful procedure to explore the efficiency of cooling and the intensity of stresses. Finally, the experimental results of this rese