Improvement Measures for CNC Machining of Titanium Alloys

Improvement of Tapping Process of Titanium Alloy CNC Machining

Structure of a standard tap. Standard straight flute taps are divided into I taper and n taper. The cutting part of I taper is 4 pitches in length. The included angle is 30°, and the front angle is 7. =7°±1°, relief angle a,,=10°±1°, the standard straight groove tap structure is shown in Figure 4. The cutting amount of the I-cone accounts for 60% of the total cutting amount, and the cutting part of the n-cone is the length of 2 pitches, and the cutting amount accounts for 40% of the total cutting amount.

Improvements to the structure of the tap. When machining titanium alloy A/2.5mm threaded holes, the standard straight groove taps wear fast, are easy to break, and cannot be taken out, resulting in scrapped workpieces. In order to increase the rigidity of the tap, improve the durability, and make the force and cutting amount of the tap more reasonable, the structure of the tap is improved. a. Increase the relief angle a"«15° to make the tool sharper for chip removal, reduce material rebound, and prevent metal materials from bonding with the flank of the tap. b. Decrease the rake angle >. 0°, the tap increases rigidity. As shown in Figure 5, by modifying the tap, not only the working time is saved by about 2.5 times, but the number of machined parts is increased by 3 to 4 times. The specific comparison data are shown in Table 2.

Choice of cutting fluid. During the machining process, the cutting tap should be filled with cutting fluid when cutting the internal thread in the prefabricated hole of the workpiece to reduce the wear of the tap and improve the quality of the thread. After years of experience, it is concluded that different cutting fluids should be selected for different materials, as shown in Table 3. After many tests and comparisons, when drilling and tapping titanium alloy materials, using soybean oil as lubricant and cooling effect is the best

Workpiece quality inspection

Use special inspection tooling, as shown in Figure 6, to process batch parts by three process methods and inspect them. Comparing the qualified quantities of products using different process methods, the statistical analysis data is shown in Table 4, and it is determined that the parts processed by the fitter using the dual-purpose drill die for drilling and tapping are the optimal process method.

Comparison of processing effects after process improvement

After actual production, the improved process method has been fully verified, and the optimized structural angle of the drill bit and the tap is well applied to the parts, which not only reduces the production cost, but also greatly improves the production efficiency. It has applied for a national invention patent, and the tooling and processing methods have been officially incorporated into the blueprint process. Since it was put into use, it has processed 3,500 titanium alloy parts, saving about 850,000 yuan in processing costs, increasing the production efficiency by more than ten times, and the quality fully meets the process design requirements. , No out-of-tolerance scrapped products are produced, and the batch production requirements are fully met.

in conclusion

(1) By replacing the quick-change drill sleeve and the quick-change tapping guide sleeve in sequence, the position of each threaded hole and the vertical centripetal axis of the axis can be precisely controlled.

(2) When drilling titanium alloy materials, the tip of the drill core is properly ground to increase the diameter of the bottom hole; the rear angle a" is increased to improve the heat dissipation conditions and avoid sticking to the knife; reduce the rake angle of the main cutting edge 7. , to increase the strength of the cutting edge.

(3) When the titanium alloy material is tapped, increase the tap back angle a. ===15° makes the tool sharper for chip removal, reduces material rebound, and prevents metal materials from bonding with the tap; reducing the rake angle by 7° produces 0°, and the tap increases the rigidity.

(4) When drilling and tapping titanium alloy materials, the use of soybean oil (not purified soybean oil) has the best lubrication and cooling effect.

(5) This set of special tooling for fitter drilling and tapping has reasonable structure design, convenient operation, easy to master the processing method, and easy to popularize. batch production requirements.