钛合金端面铣削加工中的微量润滑技术研究

摘要

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 problems 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, storage, 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 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 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 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. Completely 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 completely 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 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 flood 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 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 increase 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. 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 technique 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 progress 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 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. Parameters 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 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 research work prepared data of cutting conditions for different characteristic while using dry cutting and minimum lubrication cooling technique.

目录

英文文摘

论文说明：上海交通大学学位论文答辩决议书、LIST OF TABLES 、LIST OF FIGURES

上海交通大学学位论文原创性声明及上海交通大学学位论文版权使用授权书

ACKNOWLEDGEMENTS

CHAPTER 1 INTRODUCTION

CHAPTER 2 CUTTING FLUIDS AND MIST FORMATION

CHAPTER 3 EXPERIMENTS PREPARATION

3.1 Titanium Applications

3.2 Cutting Tools in Machining of Ti-4Al-6V

3.3 Fluid Injection System

3.4 Machine Tools

3.5 Hardness Test

3.6 Surface Roughness Test (JB-3C)

3.7 High-precision Digital Microscope(VH-8000)

3.8 Cutting Force Measurement

3.9 Temperature Measurement

3.10 Tool Deterioration Phenomena

3.11 Description of the Taguchi Method

3.12 Summary

CHAPTER 4 EXPERIMENTAL RESULTS AND DISCUSSIONS

4.1 Optimization Steps and Procedure

4.2 Optimum Dry Cutting Conditions

4.3 Optimum MQL Flow rate

4.4 Cutting Force

4.5 Parameters of Best Flow rate

4.5.1 Cutting speed vc= 48 m/min

4.5.2 Cutting speed vc= 55 m/min

4.5.3 Cutting speed vc= 65 m/min

4.5.4 Optimization of Parameters using Taguchi method

4.5.5 Multiple Performance Characteristics Optimization

4.6 Performance using High Cutting Conditions

4.7 Cutting Temperature

4.8 Summary

CHAPTER 5 CONCLUSIONS AND FUTURE WORK

REFERECES

APPENDIX

PUBLICATIONS