On the basis of the silk mechanism, a preliminary experimental study on the new technology of hot tapping was carried out, and hot tapping was obtained on the basis of the silk mechanism. Reduces cutting forces and improves thread accuracy.
1Proposal of the problem With the development of titanium alloy fasteners on the aircraft, the development and production of titanium alloy fasteners have received more and more attention in China. The application and production of a single-sided threaded nail with a single-sided structure on the aircraft has been well applied, but the internal thread processing of the nailing has always affected the domestic application and production of the nail. Big technical problems. At present, although the vibration tapping machine for titanium alloy single-sided threaded tapping has been successfully developed in China, there are still many problems (such as tap parameters must be optimized, tapping efficiency is too low, equipment operation control is cumbersome, etc.), which limits production. Batch. According to the performance of titanium alloy (TC4), we try to heat the cutting, that is, the thermal attack method.
2 Test method Because the titanium alloy (TC4) material has an intensity of 930 MPa in the annealed state, the ductience rate is only 10%-20%, and the section shrinkage is only more than 30%. It is difficult to process at room temperature. However, its strength and plasticity change greatly with temperature. Its strength decreases significantly above 500T, and plasticity increases significantly. The test adopts the flame overall heating method, the test piece material TC4, the annealed state, the thread bottom hole diameter ¢2.6, the thread size 3xl. 3 test results and discussion table 1 heating tapping test test times tap material crepe length tapping number remarks plug gauge The qualified test results of qualified 2 high-speed steel wire cone softening 3 cemented carbide plug gauge are shown in Table 1. According to the test results, heating tapping is feasible, but the tool needs to solve the high temperature resistance. Wear and other issues. It is the cutting torque curve of heating tapping and ordinary tapping under the same test conditions. It can be seen that the cutting torque of the heating tapping is significantly lower than that of the ordinary tapping. This is because the use of heating tapping can reduce the strength and hardness of the workpiece, increase the plasticity, reduce the rebound and friction of the material, and reduce the cutting force. In addition, the thread accuracy of the test piece was measured. One method is to check the overall accuracy of the thread with the over end and the end of the thread plug gauge. Another method is to clean the test piece threaded hole and fix it on the table. On the top, screw the tap to the lowest point in the hole, and load it in the radial direction of the tap, measure the radial displacement of the tap handle somewhere, to approximate the relative amount of the tapped hole of the heating tapping and the ordinary tapping. The amount of expansion of the tap) is as shown.
Heating tapping adiabatic tapping 5 笮 0 radial load W (S) tapping torque with the speed of the curve å› 2 thread hole expansion can be seen, the radial displacement of the heating tapping is larger than the ordinary tapping, This shows that heating tapping can significantly reduce the rebound and friction of the material. The tapping torque of the measured heating tapping is lower than that of the ordinary tapping, which further proves that the above conclusion is correct.
4 Conclusions Heat tapping is feasible and an effective method for attacking and snagging on difficult-to-machine materials.
Heated tapping should be made of hard alloy or coated carbide taps.
Heat tapping can significantly reduce cutting force and improve threading accuracy.
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