Papers by Keyword: Vibration Tapping

Abstract: Screw thread connection is a common way of detachable connection. The invalidation of screw thread connection will lead to mechanical failure or even retirement. Vibration tapping is essentially a kind of high-energy impact cutting which increases the rigidity of the tool. Composite vibration tapping simultaneously with repeated cutting action reduces the surface recovery of plastic materials and enhances metal cutting rate. Theoretical study and experimental results show that vibration tapping improves the metal cutting rates, enhances the machining accuracy and makes screw thread connection assembly easier. At the same time, vibration tapping process does not reduce the strength of screw thread. As the screw thread can be more uniformed cut at different depths, vibration tapping enhances the strength of screw thread slightly.

Abstract: Vibration tapping is capable to tap the deep and small hole in difficult-to-machine materials. Taguchi method is utilized to optimize the parameters in vibration tapping process in order to get the lowest maximum torque. Besides these parameters, this investigation includes the lubrication conditions comprised of dry cutting, conventional flooded lubrication and minimum quantity lubrication (MQL). The results show that the frequency and lubrication condition are significant and interaction effects exist due to these two factors.

Abstract: To solve the problems caused by the cost of metal working fluids in manufacturing processes, many methods have been employed. MQL (minimum quantity lubrication) is a successful application as a green manufacture strategy. Vibration tapping is a workable tapping method with good performance. An application of MQL technique in vibration tapping was studied. Maximum torque and chip morphology were used to evaluate the performance of MQL operation. A comparison among MQL, flooded and dry operations was carried out. The results showed that MQL decreased the maximum torque value obviously and the chip morphology under this condition was good.

Abstract: The vibration tapping technology has been employed with success on some difficult-to-machine material such as titanium alloy, hardened steel and so on. However, there are very few studies on the application of the torsion vibration tapping in particle reinforced aluminum. The tapping performance of small size thread holes in particle reinforced aluminum matrix composites Al₂O₃p/Al and SiCp/Al during common tapping and low-frequency vibration tapping using high speed steal(HSS) machine-used taps is researched experimentally in this work. The influence of vibration parameters, e.g. cutting speed V, net forward angle of each stroke LT and times of repeat cutting Q on tapping torque, tool wear, tool life and quality of thread holes is investigated during the experimentation. The results show that the common vibration tapping with small amplitude, relatively high frequency and a lot of repeat cutting times suit to tap the Al₂O₃p/Al, whereas the step vibration tapping with large amplitude, relatively low frequency and a few repeat cutting times suit to tap the SiCp/Al due to difference performance of the two kinds of material. The influence of Q and LT on the quality of thread holes, tapping torque and tool life is sensitive on the Al₂O₃p/Al, whereas the influence of V and Q on the quality of thread holes, tool wear and tool life is sensitive on the SiCp/Al. Furthermore, the optimum vibration parameter in the Al₂O₃p/Al by dry cutting is cutting speed of 400r/min, net forward angle of each stroke of 1.5°, backward angle of each stroke of 45°. The optimum vibration parameter in SiCp/Al by dry cutting is cutting speed of 220r/min, net forward angle of each stroke of 420°, backward angle of each stroke of 430°. From the test results and micrographs, it was observed that the particle could be fractured on the surface finish on tapping processing. The proper vibration tapping parameter can void the adhesion in the tap flute, decrease the tapping torque, improve the quality of thread hole and prolong the tap life.

Abstract: As high-speed steel tap is incapable of small-hole tapping (M3) in hardened steel, vibration tapping is introduced in this paper to solve this problem. Theoretic analysis with fracture mechanics indicates that the impact effect of the tap on the workpiece results in extended micro cracks and a much lower tapping torque. And the torsional rigidity of the tap is enforced in vibration tapping as proved by dynamic analysis. The experimental results show that with well chosen amplitudes, tapping torque decreases as vibration frequency increases and increases with the increase of net cutting time ratio, with the latter being the more significant influencing factor. In vibration tapping of hardened steel, 24 threads can be machined with a single tap. Vibration tapping is then proved to be a practical solution to the problem of small-hole tapping in hardened steel.