Titanium alloy processed parts have low density, high specific strength (density is generally about 4.5g/cm3, about 60% of steel), have good heat resistance strength, and can still maintain high mechanical properties in low and ultra-low temperature environments. It is a difficult-to-cut material, especially small hole tapping is very difficult. If you use unmodified taps for processing, the taps will often break because the cutting torque exceeds the strength limit of the taps, resulting in a high scrap rate and increasing product processing costs. After careful study, improvements have been made to the taps to achieve good results.
Titanium alloy manufacturer tapping small diameter internal thread cutting process force analysis
(1) Uneven force on the tap. In the process of cutting titanium alloy small-diameter internal threads, the cutting part of the cutting edge of the tool will participate in it. It is easy to see that after a round of rotation of the tap or material, the part involved in the cutting will advance by one unit in the pitch of the material. One more spalling, the processing load of each tooth is larger. When the cutting cone is cut in the hole, the cutting area gradually expands. When the tap completes the process of entering the hole, the overall area of the cutting is increased. The material of the workpiece and the friction at the cutting part gradually increase, and when the cutting layer is gradually shaped and deformed at high temperatures, it will affect the stability of the titanium alloy.
In the tapping thread, the forces on the cutting part of the tap edge are the transverse force Fa, the longitudinal force Fr and the cutting force Ft. The cutting force has a decisive effect on the torque during tapping, and the transverse and longitudinal forces have an impact on the entire cutting process. Under the normal working conditions of the tap, since the cutting area of the cutting teeth of the taps working at the same time is different, when the cutting tap When it is not long enough, the angle is larger, and the width of the cutting part of the different edge ends will be more different. Therefore, the resultant force of the radial force Fr acting on each edge of the tap is not equal to zero. When thread tapping, the cutting cone will deflect to the side where the longitudinal force is small, and the horizontal axis of the cone will be deflected, so as to approach the edge of the hole and make the hole larger.
(2) Torque is unstable. There is also the problem of unstable torque when tapping threads with other materials. However, tapping small-diameter internal threads with titanium alloys for titanium machining parts will increase protrusions. The cutting torque, the friction torque of the cutting cone and the contact surface, and the torque produced by the chips in the storage tank effectively constitute the tapping torque. Under normal circumstances, the most important thing is the cutting torque. The weight of the tap is related to its cutting thickness Ac and the number of teeth. When cutting into the bottom of the hole, the increase in the number of teeth will increase the cutting torque and friction torque. After all of them enter the hole, the torque will be increased. When the tap penetrates the hole on the other side, the torque will begin to decrease. It can be seen that in the entire cutting process, the torque goes from small to large, and then gradually decreases, and the torque is unstable.