Papers by Keyword: Tapping Torque

Abstract: In order to provide references for the application of low frequency torsional vibration tapping, three typical difficult to cut materials 30CrMnSi, GH4169 and TC4 were selected to carry out experiments. Experiment results show that net cutting angle L_T and backoff angle L_G have great influence on tapping torque, and the process parameters should be selected reasonably according to material characteristics and combining with tapping efficiency. Larger L_G and smaller L_T should be selected for materials with small elastic modulus such as TC4. Smaller L_G and larger L_T can be selected for materials similar to 30CrMnSi. For materials similar to GH4169, parameters should be selected between that of TC4 and 30CrMnSi.

Abstract: Low frequency torsional vibration tapping is an effective method to solve the problem of tapping in difficult to cut materials. Tapping parameters affect tapping torque and service life of tap, and cutting angle is the key parameter. Experiments were conducted to study the lubrication mechanism and the influence of cutting angle on lubrication effect. Experimental results indicate that the separate type boundary lubrication mode greatly enhances the lubrication effect of cutting fluid and the lubrication effect decreases with the increase of cutting angle. To obtain good technological effect, the smaller cutting angle should be selected.

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: With Third Wave AdvantEdge FEM software, an equivalent finite element model in tapping has been built, making a simulation study of the chip curling of titanium alloy TC4 and analyzing the influnce of a tap hook angle and chip flute shape on chip curling. Based on the simulation study above, the modified-tooth taps made of high-speed steel W9, which have two types of chip flute shape with a chamfer angle of 7°30´and respectively, were developed and the comparative tests of tapping TC4 have been done. The results indicates that the chip removal effects in hand tapping with the standard flute shape and respectively are on the same level, but the tapping torque has become smaller and more effective to a chamfer angle of .

Abstract: The mechanical model of the tapping torque and the friction one were established based on Theoretical Research of Tapping Forces. A series of standard taps with a cutting cone angle of 7°30′ were prepared from high-speed steel W9 and used to tap Nickel-based superalloy GH4169.It was found that the friction torque was about 45% of the total torque as tapping with the standard taps. Friction torque is the main reason in tapping difficult –to-cut materials.

Abstract: Based on the theoretical principle of tapping formation and simulation with modified-tooth tap, the relationship among the different geometric parameters of the tap was further analyzed. A series of modified-tooth taps and standard ones with a cutting cone angle of 7°30´and a outer diameter of M6, which were made from high-speed steel W9, were taken to do the comparative tapping test on nickel-based high-temperature alloy GH4169, titanium alloy TC4 and 45 steel. The test results indicated that the leading cause of difficult tapping in GH4169 and TC4 was the largeness of their friction torques which were about 35 % and 62 % of tapping torque respectively, where the frictional wear was a fundamental reason for tough tapping GH4169 and the spring back of machined surface for TC4.The obvious decreases of friction torque with the modified-tooth tap approximately 70% and 50% respectively for GH4169 and TC4 were attributed to its unique tapping formation principle of generating broaching but no remarkable effects on 45 steel in comparison with standard tap.

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.