Beryllium laser beam welding receives the influencing factor of critical power density

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Laser beam welding is received heat is conducted reach deep fusion welding two kinds of means, when soldering, be occurrence heat conducts solder or deep fusion welding suffers laser power density to control, if laser power density is more than the critical power density that metallic stuff asks, deep fusion welding appears when soldering, stuff is very expensive to the absorptivity of laser, it is 70%~90% normally, gotten welding line is had bigger deep wide than; If laser power density is less than the critical power density of material, solder is conducted with respect to occurrence heat when soldering, stuff is very low to the absorptivity of laser, it is normally 10% , welding line is had lesser deep wide than. Oxidation, stoma and crackle are 3 when when beryllium solders, appear main problems, among them crackle problem is overcome the hardest, and appearance of form of control welding line, those who reduce beryllium is fused it is one of efficient way that reduce crackle sensitivity, wanted to get the critical power density of beryllium and its influencing factor only, the need that when the laser beam welding that undertaking beryllium is received, can apply according to the project, the choice solders reasonably craft parameter, get the appearance of welding line form of need. Solder material is 40 class Beryllium, what the experiment uses is F 58mm and annulus of F 96mm Beryllium, a place stops outside beryllium annulus before solder beforehand buy ply 0.

40~0.

The Al-Si12 drill rod of 80mm expects, beryllium annulus is used before solder fixture secures test specimen, solder power is 1~ 2.

5kW. Test result makes clear, the power density that size of beryllium annulus diameter solders to generation deep frit can bring immediate impact, f58mm Beryllium annulus produces the power density threshold value of deep fusion welding to be 7´105W/cm2, and the power density threshold value that annulus of F 96mm Beryllium produces deep fusion welding is 5´105W/cm2, as the accretion of test specimen diameter, the demand of critical power density that realizes deep fusion welding to receive is less. Because test specimen diameter increases,this is hind, its curvature is reduced, in laser incident angle is 0 ° when, the back of the test specimen laser with big diameter reflexes strong Yu Xiaozhi diameter test specimen, and back reflex laser is more powerful, its are become to move Q pulse possibility by modulation inside laser resonance antrum bigger, and the power density that moves Q pulse compares density of general laser power normally tall quantitative class, after test specimen diameter increases, the formation that moves Q pulse brought about test specimen to be opposite of laser absorptivity rise. Be less than critical power to if the graph is shown 1 times,get the form appearance of welding line, be more than critical power to if the graph is shown 2 times,get the form appearance of welding line. The power density that deep to generation fusion welding receives the bulk that this extroversion bevel spends can produce immediate effect, the power density threshold values that produces deep fusion welding when 0 ° is 7´105W/cm2, the power density threshold values that deep fusion welding produces when incident angle is 3 ° is 8.

9´105W/cm2, increase as what an angle of incidence spends, the demand of critical power density that should realize deep fusion welding to receive is bigger. Because incident angle increases,this is hind, the surface of laser classics test specimen is reflexed, much reflexes laser and fiber-optic without the edge reflex answers the syntonic antrum of laser, only partial back reflexed laser to return syntonic antrum, the possibility of tone Q pulse of generation is reduced, although produce tone Q pulse, power of its peak value is relatively lesser also, and won't bring about test specimen to be opposite of laser absorptivity rise, tilt in solder connect the moves Q pulse intensity of the generation after proper point of view is met abate or disappear, same to the influence of test specimen absorptivity abate also. CNC Milling CNC Machining