A kind of combustion-supporting gas that utilizes is avoided the method for cracking when increasing laser melting coating floor height
Technical field
the present invention relates to a kind of combustion-supporting gas that utilizes and when increasing laser melting coating floor height, avoid the method for cracking, belong to field of laser cladding.
Background technology
in the industrial application of laser melting coating, in order to guarantee the thickness of coating, and for post-production reserves certain surplus, usually the height of cladding layer be there are certain requirements the i.e. requirement of minimum cladding layer height.
in actual production, in order to improve cladding layer height, usually adopt to strengthen the method for laser power input, utilize more energy input, more powder are melted in laser molten pool, to be cooled after, the height of cladding layer increases naturally.
yet, take to strengthen the way of laser power input, can cause very large harm to the quality of cladding layer, this is that characteristic by laser beam itself causes.Take optical-fiber laser as example, and the energy density of laser center part is projecting part far away.Therefore, when strengthen laser power in laser cladding process, while improving the temperature of laser molten pool, the temperature increase of molten bath central authorities is very big, is the several times of other part temperature rises of molten bath, and excessive temperature head, by the thermal crack phenomenon causing in consolidation process.Although cladding layer thickness is improved, because temperature rise is inhomogeneous, position, cladding layer central authorities boundary has produced thermal crack, has destroyed quality of cladding layer, cannot reach production requirement.
Summary of the invention
in order to address the above problem, the object of the present invention is to provide a kind of for laser melting coating and the integrated coaxial shower nozzle of refrigerating function.
in order to reach above object; the technical solution used in the present invention is: a kind of combustion-supporting gas that utilizes is avoided the method for cracking when increasing laser melting coating floor height; the gas passage of the shower nozzle adopting in laser melting coating is more than or equal to two; wherein passage passes into the mixed gas of low-voltage variation gas and low pressure combustion-supporting gas; combustion-supporting gas accounts for 15~25% of mixed gas total amount; rest channels passes into high voltage protective gas, and mixed gas and high voltage protective gas together spray from shower nozzle.
preferably, the volume ratio of mixed gas and high voltage protective gas is 1:3~1:5.
further, the air pressure of mixed gas is 1.5~2 normal atmosphere, and the air pressure of high voltage protective gas is 3~5 normal atmosphere.
further, combustion-supporting gas is acetylene.
further, shielding gas is rare gas element, is preferably nitrogen.
owing to having adopted technique scheme, a kind of combustion-supporting gas that utilizes of the present invention is avoided the method for cracking when increasing laser melting coating floor height, by mix micro-combustion-supporting gas in the shielding gas of laser cladding process, 200 ℃~400 ℃ of the temperature that can improve powder flow field and cladding yard, melt more powder; Meanwhile, make the temperature rise of laser molten pool each several part even, consolidation process is mild, eliminates central thermal crack phenomenon.Not only the thickness of cladding layer improves one times nearly, and cladding layer structure is intact, without thermal crack phenomenon, occurs.And be security consideration, it is excessive that the air pressure of combustion-supporting gas is difficult for, therefore low-pressure gas is matched with high pressure gas, both improved temperature, guarantee again safety.
Accompanying drawing explanation
accompanying drawing 1 is the structural representation of shower nozzle in the embodiment of the present invention one;
accompanying drawing 2 is the structural representation of shower nozzle in the embodiment of the present invention two.
wherein:
1, shower nozzle; 2, laser channeling; 3, powder channel; 4, the first gas passage; 5, the second gas passage; 6, laser beam; 7, treat cladding workpiece; 8, cladding layer; 9, the first gas inlet.
Embodiment
below in conjunction with accompanying drawing, preferred embodiment of the present invention is described in detail, thereby so that advantages and features of the invention can be easier to be it will be appreciated by those skilled in the art that, protection scope of the present invention is made to more explicit defining.
embodiment mono-
the present embodiment provides a kind of combustion-supporting gas that utilizes when increasing laser melting coating floor height, to avoid the method for cracking; the gas passage of the shower nozzle adopting in laser melting coating is more than or equal to two; wherein passage passes into the mixed gas of low-voltage variation gas and low pressure combustion-supporting gas; combustion-supporting gas accounts for 15~25% of mixed gas total amount; rest channels passes into high voltage protective gas, and mixed gas and high voltage protective gas together spray from shower nozzle.
the volume ratio of mixed gas and high voltage protective gas is 1:3~1:5.The air pressure of mixed gas is 1.5~2 normal atmosphere, and the air pressure of high voltage protective gas is 3~5 normal atmosphere.
combustion-supporting gas in the present embodiment adopts acetylene, also can adopt other inflammable gass in actual applications.
shielding gas is preferably used nitrogen, does not advise with helium; Use helium, first is uneconomical, and second affects intensification effect.
a kind ofly for above-mentioned a kind of combustion-supporting gas that utilizes, when increasing laser melting coating floor height, avoid the shower nozzle of the method for cracking, as shown in Figure 1, it has the laser channeling 2 that is opened in these shower nozzle 1 central authorities, be opened in laser channeling 2 one end around the other end that is connected with mixed gas adding set and run through the first gas passage 4 of shower nozzle 1 bottom surface, the one end that is opened in the first gas passage 4 peripheries the other end that is connected with powder adding set runs through the powder channel 3 of shower nozzle 1 bottom surface, the one end that is opened in powder channel 3 peripheries the other end that is connected with high voltage protective co-feeding gas device runs through the second gas passage 5 of shower nozzle 1 bottom surface.
mixed gas sprays between laser and powder, contributes to strengthen the homogeneity in powder flow field, and high voltage protective gas, in the peripheral ejection of powder, contributes to strengthen centrality and the convergency in powder flow field.
the first gas passage 4 has a plurality of, and is uniformly distributed around the central shaft of laser channeling 2; The second gas passage 5 has a plurality of, and is uniformly distributed around the central shaft of laser channeling 2.
it should be noted that; combustion-supporting gas can first mix with low-voltage variation gas; mixed gas is passed into again to the first gas passage 4 when carrying out laser melting coating; and spray from shower nozzle; also can be when carrying out laser melting coating combustion-supporting gas and low-voltage variation gas being passed into respectively to the first gas passage 4 mixes; together from shower nozzle, spray again; or also can when carrying out laser melting coating, combustion-supporting gas and low-voltage variation gas be passed into respectively to the first gas passage 4, then from shower nozzle sprays, mix respectively simultaneously.
the size at the place, gas inlet of each first gas passage 4 and the second gas passage 5 is greater than the size of gas outlet, the pressure while ejecting from shower nozzle to increase gas.
embodiment bis-
the difference of the present embodiment and embodiment mono-is: a kind of shower nozzle of the method for above-mentioned raising laser melting coating effect, as shown in Figure 2, it has the laser channeling 2 that is opened in these shower nozzle 1 central authorities, be opened in the first gas inlet 9 that the other end laser channeling 2 is connected that is connected with mixed gas adding set, one end on shower nozzle 1, laser channeling 2 one end around the other end that is connected with powder adding set runs through the powder channel 3 of shower nozzle 1 bottom surface, the one end that is opened in powder channel 3 peripheries the other end that is connected with high voltage protective co-feeding gas device runs through the second gas passage 5 of shower nozzle 1 bottom surface.
the first gas inlet 9 is more than or equal to 5cm with laser channeling 2 connection in the vertical directions apart from shower nozzle 1 bottom surface; to guarantee that shielding gas forms the stable mobile wind of wind direction within it from centre gangway ejection; and then guarantee that powder do not rushed in centre gangway, also can guarantee that shielding gas fully mixes with powder from central channel injection goes out simultaneously.
the first gas inlet 9 has a plurality of, and is uniformly distributed around the central shaft of laser channeling 2; The second gas passage 5 has a plurality of, and is uniformly distributed around the central shaft of laser channeling 2.
a kind of combustion-supporting gas that utilizes of the present invention is avoided the method for cracking when increasing laser melting coating floor height, can, guaranteeing, under the prerequisite of quality of cladding layer, to increase substantially cladding layer thickness, guarantee safety simultaneously.The shower nozzle of application the inventive method is not limited to the nozzle structure in above-mentioned two embodiment.
above-described embodiment is only explanation technical conceive of the present invention and feature, and its object is to allow person skilled in the art can understand content of the present invention and implement according to this, can not limit the scope of the invention with this.All equivalences that spirit is done according to the present invention change or modify, within all should being encompassed in protection scope of the present invention.