What is tungsten copper alloy?
Tungsten copper alloy, as a powder metallurgical composite with a wide range of uses, has also received widespread attention from the international scientific and technological community. With the research of tungsten-copper densification process in recent years, high-density tungsten-copper alloys have been gradually obtained, but it is still impossible to determine the optimal parameters of high-density tungsten-copper alloys and the influence of plastic deformation on the density structure of tungsten-copper alloys. So there are still some issues that need to be resolved.
In this paper, the mechanical ball milling, sintering, hot extrusion and hot rolling of tungsten copper alloys are analyzed and researched to achieve the optimization parameters of tungsten copper alloy compactness and grasp the influence of plastic deformation on the structure and properties of tungsten copper alloys. This will not only promote the mutual penetration and development of plastics machining disciplines, powder metallurgy, materials science and other disciplines, but also have important significance for improving the research and development and manufacturing level of tungsten-based materials in China.
Nanostructured tungsten copper alloy
Powder particle size and uniformity strongly affect the sintering characteristics of tungsten copper alloys. If the powder particle size is reduced, the sintered density and material properties will be greatly improved. Since the 1990s, nanostructured materials have been found to have specific abilities not found in conventional crystalline materials, and various types of nanomaterials have been researched and developed. Similarly, nanostructured tungsten copper alloys have also been developed.
When nano-tungsten-copper composite powders are used to prepare tungsten-copper alloys, they exhibit strong densification effects under both solid-phase and liquid-phase sintering conditions. The manufacture of ultra-fine, dispersive mixed powders of pure metals tungsten and copper is difficult. However, chemical synthesis methods such as metal oxide powder co-reduction method, chemical evaporation condensation method, chemical mechanical method, etc. are very easy to produce ultra-fine, dispersed, uniform, high-purity composite powder, and then obtain nanocrystalline tungsten copper alloy; CVC synthesis After the tungsten copper oxide nano-powder is directly pressure-molded, hydrogen reduction is performed in stages, and liquid or solid-phase sintering can also obtain a nearly full-density nano-tungsten copper alloy.
Tungsten copper wire thread machining technology
Taps are easy to wear and break when tapping is the main reason for unqualified thread machining, and taps are easy to wear and break. The main factors are
1.Due to the cnc machining characteristics of tungsten-copper alloy materials, it is easy to cause the taps to wear faster, resulting in unqualified small diameter internal threads (M3 and below M3), the thread T plug gauge cannot be screwed into place, and the tap is easy to break if it is continuously processed. ;
2. When using a tap to process a blind hole, the drilling depth does not reach the effective depth of the thread, which will cause the tap to break; ③ When using a tap to process a tungsten copper alloy blind hole, short chips are formed. Due to the small diameter of the thread, the chip space is limited, such as Failure to clean up in time will cause blockages and cause the taps to break.
Measures to solve the problem of easy wear and break of taps
1. When tapping, try to choose a rigid, coated tap, that is, replace the original high-speed steel uncoated spiral tap with a steam tempered physical coating cobalt-containing high-speed steel straight slot tap, and manually grind it. , Increase the tap shovel back and front angle, make the tap blade thickness thin, can effectively increase the rigidity and sharpness of the tap
2. When using a tap to process a blind hole, the drilling depth must be 1-2 pitches deeper than the thread to prevent the tap from hitting the bottom of the hole
3. Chips should be cleaned in time when tapping to avoid blockage of thread bottom hole. The selection of the bottom diameter of the thread is an important factor affecting the qualification of the thread. The bottom diameter of the thread is directly obtained by querying the national standard. After tapping is completed, the bottom diameter of the thread will become smaller, which will cause the thread to fail, and the tap will be easily "held" in the bottom hole of the thread. Reselect the base diameter size. In the calculation, the actual outer diameter of the external thread is used to obtain a more accurate bottom diameter of the thread.
4. According to the actual observation and analysis during tapping, the main reason for the failure of the thread is the high plasticity and elastic modulus of the tungsten copper alloy material. When the thread is processed, the plastic deformation of the metal causes the bottom diameter of the thread to become smaller.
5. Calculate the bottom diameter of the thread based on the calculation formula of the bottom diameter of the thread, and use the control variable method to perform the test on this basis. Take the M2 thread as an example, the national standard M2 thread bottom diameter is 1.567 + 0.1120, and the bottom diameter of the thread is calculated by the formula as 1.67-1.68. The range of variables and test results are shown in Table 1.
Table 1 Machining test table of different thread bottom diameters (mm)
6. Test by the control variable method in Table 1, with the thread diameter as the variable. It can be seen that the qualified rate of threads processed with the national standard thread bottom diameter is low; with the increase of the thread bottom diameter, the thread qualification rate gradually increases, and after a certain range, the qualification rate gradually decreases; the bottom diameter size is Φ1.67－ At 1.68, the TZ of the threaded plug gauge is qualified, but the screwing is not smooth; when selecting the base diameter size of Φ1.71-1.73, the TZ of the threaded plug gauge is qualified, and the screwing is relatively smooth (the threaded plug gauge Z is screwed in 3-4 buckle,
7. The national standard thread allows thread plug gauge Z to be screwed into 2-4 buckles, which meets the requirements of the national standard.) When selecting a thread bottom diameter of Φ1.75 to 1.77 and above, the thread plug gauge Z can be screwed in more than 6 Buckle, does not meet the national thread standards.
8. The test shows that the size of the bottom diameter of the screw thread is increased by 0.01 to 0.04 mm based on the formula, and the thread pass rate is the highest. By changing the process method, the torque during tapping is significantly reduced, and the wear and breakage of the tap is also significantly reduced. The number of qualified products for a single tap is increased from the original one to 20.
Tungsten copper wire thread machining conclusion
1. For M2. －6H internal thread (50 sets of 200 pieces in total, four groups in total) machining test, the thread TZ plug gauge pass rate is 95% -98%, confirming the correct selection of the bottom diameter size. When machining small threads of tungsten-copper alloy materials, the cnc machining size of the bottom diameter of the thread must be larger than that of ordinary materials, and the upper limit should be selected as far as possible. The processed parts can fully meet the design requirements, and the pass rate of one inspection can reach 98. %, Which greatly improves the machining efficiency.
2. This process method not only solves the machining problems of turning tungsten copper alloy materials and tapping small threads (below M3 and M3), but also a process method for turning tungsten copper alloy materials and tapping small threads (below M3 and M3) To provide a reference, the service life of the tap is increased by about 20 times.