| Due to the development of the manufacturing industry, deep-hole machining technology is widely applied in the field of mechanical machining. As a result, challenges are confronted,in terms of great varieties, small batch, new types of materials and increasingly high requirements of accuracy and efficiency. Topics about how to improve the quality and productivity of deep-hole drilling have attracted more and more attentions of researchers in China and other countries. However, congestion of chip removing, high oil temperature and low level of automation are still restricting the preciseness and efficiency development of deep-hole drilling technology because of the closed or semi-closed processing environments.During deep-hole drilling process, the chip congestion deteriorates the stability of the entire machining system to a large extent, which interrupts the drilling process; high oil temperature decreases the cooling effect of drilling tools, limiting their machinability, and ruins the surface integrity; low level of automation often means that, due to the closed environment of deep-hole processing, operators cannot directly observe the processing conditions which can only be estimated through touching the drill pipe, listening to the drilling noises and watching the oil pressure gauge. Therefore, in order to solve the problems of chip congestion, oil cooling and intelligent monitoring, the author developed high efficiency chip removal technology based on the pulsed fluid, integrated real time monitoring system and pneumatic negative pressure chip-extraction technique using double oil cooling for deep-hole drilling processes. The main research contents are as follows:(1) A high efficiency chip removal technology based on the pulsed fluid was studied.After sufficiently considering the pressure and the linear loss of the cutting fluid, wall friction and other factors such as the friction from the chips and self-gravity, the mathematical modelof the forces bore by the chips was established. The boundary conditions of the chip congestion were also studied. The results show that the main reasons for chip congestion are relatively low chip breaking coefficient(small area of thrust surface), uncompleted chip cutting, insufficient pressure and cutting fluid speed, etc. The unsteady turbulent transient fluid model of the pulsed cutting fluid was established and the fluid characteristics were analyzed. It is indicated that the pulsed fluid can create jet flow with superior speed and chaotic flow field which randomly varies with time. This can easily increase the chip breaking coefficient and the maximum flow speed of the cutting fluid, leading to the solutions of chip congestion problem and enhancing chip removal efficiency. A new pulsed DF system was designed. With experiments under different pulse switch frequency, f, its efficiency of chip removal was examined. When ?Hzf 7.0, the distribution of cutting fluid properties is the most advantageous for the chip removal of deep-hole drilling.(2) A integrated real time monitoring system was studied. The key signals of working condition during deep-hole processing were analyzed. The real time monitoring and warning system regarding the oil pressure and temperature, drill pipe vibration and chip removal condition signals was determined. The study of real time monitoring technology was divided into four parts. First, the mathematical model of the cutting flow field for deep-hole drilling was established. The equations of relationship between the drilling depth, spindle speed and the chip congestion degree, which influence the entrance pressure of cutting fluid field, were obtained. The real time monitoring system of oil pressure and temperature was developed.Second, the vibration equations regarding mass eccentricity, non-linear strength, dynamic drilling force and gravity of the drill pipe were acquired. The influence of the spindle speed on the movement of the drill pipe was analyzed. The vibration measuring principle of parallel laser was studied. The real time monitoring system of the drill pipe vibration signals based on the IG-28 parallel laser sensors was developed. Third, sound pressure difference of pulsed ultrasound under conditions with and without the chips in drill pipe was analyzed. The real time monitoring system of the chip removal condition, which is based on the mechanism ofultrasonic flaw detection, was schematically designed. The maximum time interval between two adjacent chips removed, ?t, was selected as the measurement to determine whether the chip removal condition is regular or not. The prewarning value,YJ?t, was set, which realizes the monitoring and the prewarning of chip removal. Forth, the integrated system for monitoring four types of signals and prewarning was completed, therefore improving the level of automation.(3) A pneumatic negative pressure chip-extraction system for deep-hole drilling machine was designed. It includes three major components, which are pneumatic negative pressure chip-extraction part, water cycling part and the self-cooled part for the heat dissipation of the negative pressure chip-extraction box. Under the impact of compressed cool air, an area of negative pressure is created at the tale of the drill pipe, which can generate the effect of chip-extraction. Meanwhile, part of the cutting fluid is atomized and exchanges the heat with the compressed cool air, completing the first cooling. Water cycling channels are installed inside the box walls, which can maintain the low temperature of the box. When cutting fluid flows through, the heat is exchanges with the cooled box and the fluid is cooled second time. The flow and temperature field of the cutting fluid in pneumatic negative pressure chip-extraction system were simulated and analyzed. Results show that the cutting fluid is well distributed and the cooling effect is improved using the designed system.In conclusion,the results of this article can effectively improve the chip removal preformance of deep hole processing,the automation level of deep hole machines and the cooling effect of the cutting fluid,therefore promoting the development of high efficiency and intelligentization of deep hole processing technology. |
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