CN109759663B - Stainless steel/aluminum alloy dissimilar metal brazing attachment method - Google Patents
Stainless steel/aluminum alloy dissimilar metal brazing attachment method Download PDFInfo
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- CN109759663B CN109759663B CN201910044322.9A CN201910044322A CN109759663B CN 109759663 B CN109759663 B CN 109759663B CN 201910044322 A CN201910044322 A CN 201910044322A CN 109759663 B CN109759663 B CN 109759663B
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Abstract
The invention relates to a method for brazing and assembling stainless steel/aluminum alloy dissimilar metal, which comprises the steps of cleaning a tin-coated surface of a stainless steel pipe, scraping and cleaning the surface of a tin-filling tank of an aluminum alloy flange plate, then performing heating brazing and assembling, and finally cleaning a product. And detecting to ensure that the qualified requirements of products are met. The scraping treatment is carried out after the heating process after cleaning, and then the rotary brazing attachment under the guiding of the mandrel is carried out, so that the temperature field difference is reduced, the oxide residue is reduced, and the precipitation capacity of pores of a liquid tin brazing seam is promoted, therefore, in the brazing attachment process of the stainless steel pipe and the aluminum alloy flange plate, the defects of the pores, the oxide slag inclusion and the like are effectively controlled, the qualification rate is greatly improved, and the process requirement of the control of the brazing attachment process of the product and the qualified use requirement of the product are met.
Description
Technical Field
The invention relates to a stainless steel/aluminum alloy dissimilar metal brazing attachment method, and belongs to the technical field of welding.
Background
As a tin-lead soldering and assembling process of stainless steel/aluminum alloy dissimilar metal, the assembling process has important influence on the stainless steel/aluminum alloy dissimilar metal soldering.
The steel/aluminum welding structure has important application in the industrial departments of aerospace, transportation, national defense and the like. But the connection problem of the two is always a technical difficulty in the field of welding. In the past, a great deal of research work has been carried out in the field of steel/aluminum dissimilar metal connection at home and abroad, and engineering application in non-sealing structures of automobiles, satellites, high-speed rails, airplanes and the like is realized.
In the prior art, a sealing component welded by a stainless steel/aluminum alloy dissimilar metal conduit structure is adopted. The product manufacturing unit adopts a tin-lead soldering process to realize engineering application, but has a weak link in the aspect of brazing seam quality stability control. Among them, the attachment method in the brazing process of the product is also an important factor causing the quality of the brazing seam to be unstable.
In addition, the aluminum alloy flange plate is subjected to the product mounting process when the tin-lead solder is required to be heated again to be molten after tin filling and machining are finished. In the assembling process, the key process of avoiding defects and improving the quality of a drill seam is correctly operated and controlled.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, provides a method for brazing and connecting dissimilar metals of stainless steel/aluminum alloy, and solves the problem that products cannot meet the qualified standard of brazing seams due to the defects of pores, oxidation, slag inclusion and the like in brazing.
The purpose of the invention is realized by the following technical scheme:
provides a stainless steel/aluminum alloy dissimilar metal brazing attachment method, which comprises the following steps:
(1) carrying out sand blowing, galvanizing and copper plating treatment on a tin bath of the aluminum alloy workpiece; filling tin into a tin bath of the aluminum alloy workpiece, and then performing integral anodization treatment;
(2) cleaning the surface of the stainless steel pipe fitting;
(3) cleaning the surface of a tin bath of the anodized aluminum alloy workpiece;
(4) putting the aluminum alloy workpiece into a brazing furnace, heating until the brazing filler metal is molten, and taking out;
(5) putting the stainless steel pipe fitting into a tin bath, and curing the brazing filler metal;
(6) and (5) cleaning.
Preferably, cleaning the surface of the stainless steel pipe fitting comprises: cleaning the position of the stainless steel pipe to be brazed after tin coating with alcohol, drying the stainless steel pipe to be brazed, and then coating a layer of micro-active soldering flux on the tin coating surface.
Preferably, the micro-active brazing flux is liquid tin.
Preferably, the cleaning of the tin bath surface of the aluminum alloy workpiece in the step (3) comprises the following steps: firstly, scraping anodized materials on the surface of a tin bath of an anodized aluminum alloy workpiece, and then cleaning the aluminum alloy workpiece with alcohol and drying the aluminum alloy workpiece by blowing.
Preferably, the specific method for placing the aluminum alloy workpiece into the brazing furnace and heating until the brazing filler metal is melted and taken out in the step (4) is as follows: heating a brazing furnace to 85-95 ℃, preserving heat for 1 hour, then putting the aluminum alloy workpiece into an electric furnace for heating, taking the aluminum alloy workpiece out of the electric furnace after the brazing filler metal is molten, and scraping off the brazing filler metal oxidized by heating on the inner surface of a tin bath of the aluminum alloy workpiece.
Preferably, the step (5) of loading the stainless steel pipe fitting into the tin bath further comprises clockwise rotation for 2-3 circles and anticlockwise rotation for 2-3 circles, wherein brazing filler metal and soldering flux are added according to requirements, and the full welding angle is ensured.
Preferably, the washing in step (6) comprises:
6.1, putting the mixture into flowing hot water at the temperature of 50-60 ℃, and drying the mixture;
6.2 soaking in alcohol, cleaning and drying;
6.3 mechanically cleaning the brazing seam until no residual brazing flux is observed visually.
Preferably, the mechanically performing the brazing seam cleaning comprises: and wrapping silk cloth outside the rigid welding wire bent into a circular ring shape, dipping alcohol, and sleeving the silk cloth on the inner side and the outer side of the stainless steel pipe fitting to clean the brazing seam.
Preferably, the method further comprises the step (7), the brazed assembly product is subjected to a gas tightness test, and the brazing seam does not allow leakage.
Preferably, the method further comprises the step (8) of carrying out CT scanning imaging inspection on the welding seams, wherein pores, slag inclusion or unfused parts exceeding the standard are not allowed to exist at the welding seams.
Preferably, the method further comprises the step (9) of carrying out endoscopic inspection, wherein residual brazing flux is not allowed to exist at the brazing seam.
Preferably, the sand blowing in the step (1) comprises the following steps:
a. cleaning and checking the surface of the aluminum alloy flange plate;
b. clamping an aluminum alloy workpiece by using a positioner, and setting a tilt angle theta of the positioner; adjusting the rotating speed of the positioner to keep the sand blowing surface of the aluminum alloy workpiece at a required constant linear speed; the spray gun blows sand vertically downwards;
c. adjusting the posture of the positioner to complete sand blowing of the inner surface of the tin bath;
d. and performing appearance inspection on the sand blowing surface, and blowing sand again if the sand blowing surface does not meet the requirements.
Preferably, the sand blowing of the inner surface of the narrow deep groove is completed by adjusting the posture of the positioner in the step c, and the method comprises the following steps: and the position changing machine respectively horizontally rotates to complete sand blowing at the bottom of the tin bath, inwards inclines theta and rotates to complete sand blowing of the inner bath surface of the tin bath, outwards inclines theta and rotates to complete sand blowing of the outer bath surface of the tin bath.
Preferably, the galvanization in the step (1) comprises the following steps:
a. polishing the aluminum alloy workpiece by using chemical polishing solution;
b. carrying out alkali corrosion on the aluminum alloy workpiece and cleaning;
c. carrying out light extraction and cleaning on the aluminum alloy workpiece;
d. primary zinc dipping and cleaning;
e. and (5) soaking zinc again and cleaning.
Preferably, the primary zincating method in the step d comprises the following steps: soaking the aluminum alloy workpiece in a zinc dipping solution at the temperature of 30-40 ℃ for 60-80 s until the tin bath of the aluminum alloy workpiece produces a uniform dark gray film.
Preferably, the method for re-zincating in the step e comprises the following steps: and controlling the temperature of the zinc dipping tank by adopting a water bath heating mode, and soaking the zinc dipping tank in a solution at the temperature of 30-40 ℃ for 60-70 s until a tin bath of the aluminum alloy workpiece generates a uniform gray yellow film.
Preferably, the copper plating in step (1) comprises the following steps:
one-time copper plating
1.1 carrying out impact current copper plating on a tin bath of the aluminum alloy workpiece after the completion of zinc plating by using a copper plating bath solution, wherein the current intensity of a single aluminum alloy workpiece is 80-110A/dm2；
1.2 adopting a copper plating bath solution to plate copper on a tin bath of an aluminum alloy workpiece, wherein the current intensity of a single part is 15-30A/dm2；
1.3 cleaning the aluminum alloy workpiece;
secondary and secondary copper plating
2.1 adopting a copper plating bath solution to carry out impact current copper plating, wherein the current intensity of a single part is 50-70A/dm2；
2.2 adopting a copper plating bath solution to plate copper on a tin bath of the aluminum alloy workpiece, wherein the current intensity of a single part is 10-20A/dm2
And 2.3 cleaning the aluminum alloy workpiece and drying.
Preferably, copper plating is performed once within 1.5min after the galvanization.
Preferably, when the impact current copper plating is carried out in the step 1.1, the temperature of a copper plating bath is 15-40 ℃, the electroplating time is 2-4 min, and an aluminum alloy workpiece swings back and forth and rotates circumferentially in the impact process; the specific method for copper plating of the tin bath of the aluminum alloy workpiece by using the copper plating bath solution in the step 1.2 comprises the following steps: the temperature of the copper plating bath is 15-40 ℃, the electroplating time is 2-4 min, and the aluminum alloy workpiece swings back and forth and rotates circumferentially.
Preferably, the time interval after step 1.2 is completed to the start of step 2.1 is less than 2 min.
Preferably, the specific method for carrying out impact current copper plating by using the copper plating bath solution in the step 2.1 comprises the following steps: the temperature of the copper plating bath is 15-35 ℃, the electroplating time is 2-4 min, and the aluminum alloy workpiece swings back and forth and rotates circumferentially in the impact process; the specific method for plating copper on the narrow and deep groove of the aluminum alloy flange plate by using the copper plating bath solution in the step 2.2 comprises the following steps: the temperature of the copper plating bath is 15-40 ℃, the electroplating time is 7-9 min, and the aluminum alloy workpiece swings back and forth and rotates circumferentially in the impact process.
Preferably, the bath solution for the primary and secondary copper plating is a copper cyanide solution.
Preferably, the tin groove is an annular groove, the groove depth is 15-25 mm, and the groove width is 3-10 mm.
Compared with the prior art, the invention has the following advantages:
(1) the scraping treatment is carried out after cleaning, the scraping treatment is carried out after heating, and the generation of overproof defects such as air holes, oxidation, slag inclusion, incomplete fusion and the like is controlled by adopting a clockwise and anticlockwise rotating method in the brazing assembling process, so that the brazing rate meeting the standard requirement of a brazing seam is obtained.
(2) In the cleaning process after brazing, under the combined action of flowing hot water and alcohol cleaning at 50-60 ℃, the pH value is 5-8, and the use requirement of subsequent product test storage is ensured.
(3) The invention carries out industrial CT scanning inspection and endoscopy on the product, ensures the internal and external quality of the front welding line and controls the quality state within a qualified range.
Drawings
FIG. 1 is a schematic structural view of a stainless steel pipe fitting;
FIG. 2 is a schematic view of an aluminum alloy flange;
FIG. 3 is a schematic view of a mandrel;
FIG. 4 is a schematic view of a heating furnace;
FIG. 5 is a schematic view of product attachment.
Detailed Description
The aluminum alloy flange plate provided by the invention is provided with an annular groove as a tin bath to be welded with a stainless steel pipe fitting, and the procedures of sand blowing, zinc dipping and copper plating are firstly carried out in the tin bath. The consistency of the surface roughness of the tin bath is ensured in the sand blowing process, and the uniformity of zinc and copper is ensured in the zinc dipping and copper plating processes. The tin bath is a narrow slit, and the depth is deeper, which is not beneficial to brazing. The invention provides a method for brazing and connecting dissimilar metals of stainless steel/aluminum alloy, which comprises the following steps:
(1) carrying out sand blowing, galvanizing and copper plating treatment on a tin bath of the aluminum alloy workpiece; filling tin into a tin bath of the aluminum alloy workpiece, and then performing integral anodization treatment;
(2) cleaning the surface of the stainless steel pipe fitting
Cleaning a position of the stainless steel pipe fitting to be brazed after tin coating with alcohol, drying the position, and then coating a layer of micro-active soldering flux on the surface of the tin coating; the micro-active soldering flux is liquid tin.
(3) And (3) filling tin into the tin bath of the aluminum alloy flange plate after copper plating, and then performing integral anodization treatment to clean the surface of the tin bath of the aluminum alloy flange plate after anodization treatment.
Firstly, scraping anodized materials on the surface of a tin bath of the anodized aluminum alloy flange plate, and then cleaning the flange plate by using alcohol and drying the flange plate by blowing.
(4) Heating of
Heating a brazing furnace to 85-95 ℃, preserving heat for 1 hour, then putting the cleaned flange plate into an electric furnace for heating, taking out the flange plate from the electric furnace after the brazing filler metal is molten, and scraping off the brazing filler metal oxidized by heating on the inner surface of a tin bath of the flange plate.
(5) Welding of
Inserting a mandrel into a central hole of the flange plate, guiding by the mandrel, inserting the corrugated pipe into a tin melting ring groove through the mandrel, keeping tin in the tin melting groove in a melting state, clockwise rotating for 2-3 circles, anticlockwise rotating for 2-3 circles, adding brazing filler metal and brazing flux according to needs, and wiping off the brazing flux after the brazing filler metal is solidified. Ensuring the fillet is full.
(6) Cleaning of
a) Cleaning with hot water
And (3) putting the brazed product into flowing hot water at the temperature of 50-60 ℃, cleaning and drying.
b) Alcohol cleaning
In order to further remove the residual oxide and water stain after hot water cleaning, alcohol soaking, cleaning and blow-drying are carried out.
c) Mechanical cleaning
Wrapping silk cloth with a circular rigid welding wire, dipping alcohol, further cleaning the inside and outside of the brazing seam until no brazing flux is left by visual observation, and drying.
(7) Air tightness test
a) Test fixture
Prepare the air-tight test fixture and clean it with alcohol.
b) Card holder
The assembly product after the steel/aluminum dissimilar metal is brazed is placed into an air tightness test fixture, the length is ensured by a tool, and the product deformation is prevented.
c) Pressure test
Air at 0.6MPa was introduced into the inner chamber and the assembly was placed in alcohol for 5 minutes without allowing leakage. And detecting the sealing performance of the brazing seam.
d) Pressure relief
And opening the air release valve, unloading the clamp after sufficient pressure relief, cleaning the assembly product with alcohol and drying.
(8) CT examination
The product is subjected to CT scanning imaging inspection on the welding seam by an industrial CT system, and the defects of air holes, slag inclusion, non-fusion and the like exceeding the standard are not allowed to exist.
(9) Endoscopic examination
The product is subjected to endoscopic inspection, and the existence of attachments such as residual brazing flux is not allowed.
In the step (1), the sand blowing uniformity needs to be ensured, and the method specifically comprises the following steps:
a. cleaning and checking the surface of the aluminum alloy flange plate;
b. the aluminum alloy workpiece is clamped by the aid of the positioner, the positioner can drive the aluminum alloy flange to axially rotate and tilt, an inclination angle theta of the positioner can be shifted by +/-90 degrees, and the aluminum alloy flange is clamped to a three-jaw chuck of the positioner. Setting the inclination angle theta of the positioner; adjusting the rotating speed of the positioner to keep the sand blowing surface of the aluminum alloy workpiece at a required constant linear speed; the spray gun blows sand vertically downwards; the height distance between the spray gun and the surface of the aluminum alloy flange part is 100-300 mm, and the sand blowing pressure is 0.5-1.5 MPa.
c. Adjusting the posture of the positioner to complete sand blowing of the inner surface of the tin bath; and the position changing machine respectively horizontally rotates to complete sand blowing at the bottom of the tin bath, inwards inclines theta and rotates to complete sand blowing of the inner bath surface of the tin bath, outwards inclines theta and rotates to complete sand blowing of the outer bath surface of the tin bath. And controlling the position changing machine to rotate for 3-6 turns in the sand blowing process at the bottom of the groove, controlling the position changing machine to rotate for 5-8 turns in the sand blowing process of the inner groove surface of the narrow deep groove and the sand blowing process of the outer groove surface of the narrow deep groove, or controlling the sand blowing at the bottom of the groove, the sand blowing at the inner groove surface of the narrow deep groove and the sand blowing at the outer groove surface of the narrow deep groove, and finishing the sand blowing when the sand blowing surface is dark gray.
d. And performing appearance inspection on the sand blowing surface, and blowing sand again if the sand blowing surface does not meet the requirements.
The galvanizing in the step (1) needs to ensure the uniformity of galvanizing, and the method specifically comprises the following steps:
a. polishing the aluminum alloy workpiece by using chemical polishing solution;
b. carrying out alkali corrosion on the aluminum alloy workpiece and cleaning;
c. carrying out light extraction and cleaning on the aluminum alloy workpiece;
d. primary zinc dipping and cleaning; soaking the aluminum alloy workpiece in a zinc dipping solution at the temperature of 30-40 ℃ for 60-80 s until the tin bath of the aluminum alloy workpiece produces a uniform dark gray film. The workpiece swings up and down 7-8 times in the water tank, and the workpiece is damaged by excessive impact force. After taking out, the tin bath is washed by a water pipe or a water gun connected with running water at room temperature until the tin bath is cleaned at room temperature.
e. And (5) soaking zinc again and cleaning. And controlling the temperature of the zinc dipping tank by adopting a water bath heating mode, and soaking the zinc dipping tank in a solution at the temperature of 30-40 ℃ for 60-70 s until a tin bath of the aluminum alloy workpiece generates a uniform gray yellow film. The workpiece swings up and down 7-8 times in the water tank, and the workpiece is damaged by excessive impact force. After taking out, the ring groove is washed by a water pipe or a water gun connected with running water at room temperature until the ring groove is cleaned at room temperature.
In the step (1), copper plating needs to be carried out continuously and uniformly, and copper plating is carried out once within 1.5min after zinc plating. The method specifically comprises the following steps:
one-time copper plating
1.1 carrying out impact current copper plating on a tin bath of the aluminum alloy workpiece after the completion of zinc plating by using a copper plating bath solution, wherein the current intensity of a single aluminum alloy workpiece is 80-110A/dm2(ii) a The temperature of the copper plating bath is 15-40 ℃, the electroplating time is 2-4 min, and the aluminum alloy workpiece swings back and forth and rotates circumferentially in the impact process;
1.2 adopting a copper plating bath solution to plate copper on a tin bath of an aluminum alloy workpiece, wherein the current intensity of a single part is 15-30A/dm2(ii) a The specific method for plating copper on the tin bath of the aluminum alloy workpiece by adopting the copper plating bath solution comprises the following steps: the temperature of the copper plating bath is 15-40 ℃, the electroplating time is 2-4 min, and the aluminum alloy workpiece swings back and forth and rotates circumferentially.
1.3 cleaning the aluminum alloy workpiece.
Secondary and secondary copper plating
2.1 adopting a copper plating bath solution to carry out impact current copper plating, wherein the current intensity of a single part is 50-70A/dm2(ii) a The time interval from the completion of step 1.2 to the start of step 2.1 is less than 2 min.
2.2 adopting a copper plating bath solution to plate copper on a tin bath of the aluminum alloy workpiece, wherein the current intensity of a single part is 10-20A/dm2
And 2.3 cleaning the aluminum alloy workpiece and drying.
The invention is described in further detail below with reference to the figures and the embodiments.
As shown in fig. 1, the narrow gap groove depth of the aluminum alloy flange is Hb; an inner diameter N; an outer diameter W. The inner diameter of the flange is D, and the outer diameter is D. The diameter phi c of the mandrel is smaller than the diameter phi B of the inner hole of the flange plate, the height Hc of the mandrel is larger than the height Hd of a part product, and the mandrel is of a solid structure.
Example 1: the method for brazing the steel/aluminum dissimilar metal with the inner diameter phi of the groove of the aluminum alloy flange plate being 70 mm.
(1) Cleaning the surface of the stainless steel pipe fitting
Cleaning a position of the stainless steel pipe fitting to be brazed after tin coating with alcohol, drying the position, and then coating a layer of micro-active soldering flux on the surface of the tin coating;
(2) and cleaning the surface of the tin bath of the aluminum alloy flange plate.
Firstly, scraping anodized materials on the surface of a tin bath of the anodized aluminum alloy flange plate, and then cleaning the flange plate by using alcohol and drying the flange plate by blowing.
(3) Heating of
Heating a brazing furnace to 85-95 ℃, preserving heat for 1 hour, then putting the cleaned flange plate into an electric furnace for heating, taking out the flange plate from the electric furnace after the brazing filler metal is molten, and scraping off the brazing filler metal oxidized by heating on the inner surface of a tin bath of the flange plate.
(4) Welding of
Inserting a mandrel into a central hole of the flange plate, guiding by the mandrel, inserting the corrugated pipe into the tin melting ring groove through the mandrel, rotating clockwise for 2-3 circles, rotating anticlockwise for 2-3 circles, adding brazing filler metal and brazing flux according to requirements, and wiping off the brazing flux after the brazing filler metal is solidified.
(5) Cleaning of
And (3) putting the brazed product into flowing hot water at the temperature of 50-60 ℃, cleaning and drying.
In order to further clear the residual oxide and water stain after the hot water cleaning, alcohol soaking, cleaning and blow-drying are carried out.
And (3) checking and cleaning the residual soldering flux at the brazing seam by using a hard plastic cleaning tool and a reflector, wrapping silk cloth by using a welding wire bent into a circular ring shape, dipping alcohol, further cleaning the brazing seam until no residual soldering flux is observed visually, and drying.
(6) Air tightness test
Prepare the air-tight test fixture and clean it with alcohol.
The assembly product after the steel/aluminum dissimilar metal is brazed is placed into an air tightness test fixture, the length is ensured by a tool, and the product deformation is prevented.
Air at 0.6MPa was introduced into the inner chamber and the assembly was placed in alcohol for 5 minutes without allowing leakage.
And opening the air release valve, unloading the clamp after sufficient pressure relief, cleaning the assembly product with alcohol and drying.
(7) CT examination
The product is subjected to CT scanning imaging inspection on the welding seam by an industrial CT system, and the defects of air holes, slag inclusion, non-fusion and the like exceeding the standard are not allowed to exist.
(8) Endoscopic examination
The product is subjected to endoscopic inspection, and the existence of attachments such as residual brazing flux is not allowed.
Example 2: the method for brazing and connecting the steel/aluminum dissimilar metal with the inner diameter phi of 320mm in the groove of the aluminum alloy flange plate.
(1) Cleaning the surface of the stainless steel pipe fitting
Cleaning a position of the stainless steel pipe fitting to be brazed after tin coating with alcohol, drying the position, and then coating a layer of micro-active soldering flux on the surface of the tin coating;
(2) and cleaning the surface of the tin bath of the aluminum alloy flange plate.
Scraping the anodized material on the surface of the tin bath of the anodized aluminum alloy flange plate, cleaning the flange plate by using alcohol and drying the flange plate by blowing.
(3) Heating of
Heating a brazing furnace to 85-95 ℃, preserving heat for 1 hour, then putting the cleaned flange plate into an electric furnace for heating, taking out the flange plate from the electric furnace after the brazing filler metal is molten, and scraping off the brazing filler metal oxidized by heating on the inner surface of a tin bath of the flange plate.
(4) Welding of
Inserting a mandrel into a central hole of the flange plate, guiding by the mandrel, inserting the corrugated pipe into the tin melting ring groove through the mandrel, rotating clockwise for 2-3 circles, rotating anticlockwise for 2-3 circles, adding brazing filler metal and brazing flux according to requirements, and wiping off the brazing flux after the brazing filler metal is solidified.
(5) Cleaning of
And (3) putting the brazed product into flowing hot water at the temperature of 50-60 ℃, cleaning and drying.
In order to further clear the residual oxide and water stain after the hot water cleaning, alcohol soaking, cleaning and blow-drying are carried out.
And (3) checking and cleaning the residual soldering flux at the brazing seam by using a hard plastic cleaning tool and a reflector, wrapping silk cloth by using a welding wire bent into a circular ring shape, dipping alcohol, further cleaning the brazing seam until no residual soldering flux is observed visually, and drying.
(6) Air tightness test
Prepare the air-tight test fixture and clean it with alcohol.
The assembly product after the steel/aluminum dissimilar metal is brazed is placed into an air tightness test fixture, the length is ensured by a tool, and the product deformation is prevented.
Air at 0.6MPa was introduced into the inner chamber and the assembly was placed in alcohol for 5 minutes without allowing leakage.
And opening the air release valve, unloading the clamp after sufficient pressure relief, cleaning the assembly product with alcohol and drying.
(7) CT examination
The product is subjected to CT scanning imaging inspection on the welding seam by an industrial CT system, and the defects of air holes, slag inclusion, non-fusion and the like exceeding the standard are not allowed to exist.
(8) Endoscopic examination
The product is subjected to endoscopic inspection, and the existence of attachments such as residual brazing flux is not allowed.
The above description is only for the best mode of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.
Those skilled in the art will appreciate that the invention may be practiced without these specific details.
Claims (21)
1. A stainless steel/aluminum alloy dissimilar metal brazing attachment method is characterized by comprising the following steps:
(1) carrying out sand blowing, galvanizing and copper plating treatment on a tin bath of the aluminum alloy workpiece; filling tin into a tin bath of the aluminum alloy workpiece, and then performing integral anodization treatment;
(2) cleaning the surface of the stainless steel pipe fitting;
(3) cleaning the surface of a tin bath of the anodized aluminum alloy workpiece;
(4) putting the aluminum alloy workpiece into a brazing furnace, heating until the brazing filler metal is molten, and taking out;
(5) putting the stainless steel pipe fitting into a tin bath, and curing the brazing filler metal;
(6) cleaning;
the copper plating in the step (1) comprises the following steps:
one-time copper plating
1.1 carrying out impact current copper plating on a tin bath of the aluminum alloy workpiece after the completion of zinc plating by using a copper plating bath solution, wherein the current intensity of a single aluminum alloy workpiece is 80-110A/dm2；
1.2 adopting a copper plating bath solution to plate copper on a tin bath of an aluminum alloy workpiece, wherein the current intensity of a single part is 15-30A/dm2；
1.3 cleaning the aluminum alloy workpiece;
secondary and secondary copper plating
2.1 adopting a copper plating bath solution to carry out impact current copper plating, wherein the current intensity of a single part is 50-70A/dm2；
2.2 adopting a copper plating bath solution to plate copper on a tin bath of the aluminum alloy workpiece, wherein the current intensity of a single part is 10-20A/dm2
2.3 cleaning and drying the aluminum alloy workpiece;
the step (3) of cleaning the surface of the tin bath of the aluminum alloy workpiece comprises the following steps: firstly, scraping anodized materials on the surface of a tin bath of an anodized aluminum alloy workpiece, and then cleaning the aluminum alloy workpiece with alcohol and drying the aluminum alloy workpiece by blowing.
2. The method of dissimilar metal brazing attachment of stainless steel/aluminum alloy according to claim 1, wherein cleaning the surface of the stainless steel tubular member comprises: cleaning the position of the stainless steel pipe to be brazed after tin coating with alcohol, drying the stainless steel pipe to be brazed, and then coating a layer of micro-active soldering flux on the tin coating surface.
3. The method of dissimilar metal brazing attachment of stainless steel/aluminum alloy according to claim 2, wherein: the micro-active soldering flux is liquid tin.
4. The method of dissimilar metal brazing attachment of stainless steel/aluminum alloy according to claim 1, wherein: the specific method for putting the aluminum alloy workpiece into the brazing furnace to be heated until the brazing filler metal is molten and taken out in the step (4) is as follows: heating a brazing furnace to 85-95 ℃, preserving heat for 1 hour, then putting the aluminum alloy workpiece into an electric furnace for heating, taking the aluminum alloy workpiece out of the electric furnace after the brazing filler metal is molten, and scraping off the brazing filler metal oxidized by heating on the inner surface of a tin bath of the aluminum alloy workpiece.
5. The method of dissimilar metal brazing attachment of stainless steel/aluminum alloy according to claim 1, wherein: and (5) loading the stainless steel pipe fitting into the tin bath, further comprising clockwise rotating for 2-3 circles, and then anticlockwise rotating for 2-3 circles, wherein brazing filler metal and soldering flux are added according to requirements, and the full welding angle is ensured.
6. The method of dissimilar metal brazing attachment of stainless steel/aluminum alloy according to claim 1, wherein: the cleaning in the step (6) comprises:
6.1, putting the mixture into flowing hot water at the temperature of 50-60 ℃, and drying the mixture;
6.2 soaking in alcohol, cleaning and drying;
6.3 mechanically cleaning the brazing seam until no residual brazing flux is observed visually.
7. The method of dissimilar metal brazing attachment of stainless steel/aluminum alloy according to claim 6, wherein: the mechanical brazing seam cleaning method comprises the following steps: and wrapping silk cloth outside the rigid welding wire bent into a circular ring shape, dipping alcohol, and sleeving the silk cloth on the inner side and the outer side of the stainless steel pipe fitting to clean the brazing seam.
8. The method of dissimilar metal brazing attachment of stainless steel/aluminum alloy according to claim 1, wherein: and (7) carrying out an air tightness test on the brazed assembly product, wherein the brazing seam is not allowed to leak.
9. The method of dissimilar metal brazing attachment of stainless steel/aluminum alloy according to claim 8, wherein: and (8) carrying out CT scanning imaging inspection on the welding seam, wherein the welding seam is not allowed to have air holes, slag inclusion or unfused exceeding the standard.
10. The method of dissimilar metal brazing attachment of stainless steel/aluminum alloy according to claim 9, wherein: the method also comprises a step (9) of carrying out endoscopic inspection, wherein residual brazing flux is not allowed to exist at the brazing seam.
11. The dissimilar metal brazing attachment method of stainless steel/aluminum alloy according to claim 1 or 4, wherein: the sand blowing in the step (1) comprises the following steps:
a. cleaning and checking the surface of the aluminum alloy flange plate;
b. clamping an aluminum alloy workpiece by using a positioner, and setting a tilt angle theta of the positioner; adjusting the rotating speed of the positioner to keep the sand blowing surface of the aluminum alloy workpiece at a required constant linear speed; the spray gun blows sand vertically downwards;
c. adjusting the posture of the positioner to complete sand blowing of the inner surface of the tin bath;
d. and performing appearance inspection on the sand blowing surface, and blowing sand again if the sand blowing surface does not meet the requirements.
12. The method of dissimilar metal brazing attachment of stainless steel/aluminum alloy according to claim 11, wherein: and c, adjusting the posture of the positioner to complete sand blowing of the inner surface of the narrow and deep groove, and the method comprises the following steps: and the position changing machine respectively horizontally rotates to complete sand blowing at the bottom of the tin bath, inwards inclines theta and rotates to complete sand blowing of the inner bath surface of the tin bath, outwards inclines theta and rotates to complete sand blowing of the outer bath surface of the tin bath.
13. The dissimilar metal brazing attachment method of stainless steel/aluminum alloy according to claim 1 or 4, wherein: the galvanization in the step (1) comprises the following steps:
a. polishing the aluminum alloy workpiece by using chemical polishing solution;
b. carrying out alkali corrosion on the aluminum alloy workpiece and cleaning;
c. carrying out light extraction and cleaning on the aluminum alloy workpiece;
d. primary zinc dipping and cleaning;
e. and (5) soaking zinc again and cleaning.
14. The method of dissimilar metal brazing attachment of stainless steel/aluminum alloy according to claim 13, wherein: the primary zinc dipping method in the step d comprises the following steps: soaking the aluminum alloy workpiece in a zinc dipping solution at the temperature of 30-40 ℃ for 60-80 s until the tin bath of the aluminum alloy workpiece produces a uniform dark gray film.
15. The method of dissimilar metal brazing attachment of stainless steel/aluminum alloy according to claim 14, wherein: the method for soaking zinc again in the step e comprises the following steps: and controlling the temperature of the zinc dipping tank by adopting a water bath heating mode, and soaking the zinc dipping tank in a solution at the temperature of 30-40 ℃ for 60-70 s until a tin bath of the aluminum alloy workpiece generates a uniform gray yellow film.
16. The method of dissimilar metal brazing attachment of stainless steel/aluminum alloy according to claim 1, wherein: and carrying out primary copper plating within 1.5min after galvanization.
17. The method of dissimilar metal brazing attachment of stainless steel/aluminum alloy according to claim 16, wherein: when impact current copper plating is carried out in the step 1.1, the temperature of a copper plating bath is 15-40 ℃, the electroplating time is 2-4 min, and an aluminum alloy workpiece swings back and forth and rotates circumferentially in the impact process; the specific method for copper plating of the tin bath of the aluminum alloy workpiece by using the copper plating bath solution in the step 1.2 comprises the following steps: the temperature of the copper plating bath is 15-40 ℃, the electroplating time is 2-4 min, and the aluminum alloy workpiece swings back and forth and rotates circumferentially.
18. The method of dissimilar metal brazing attachment of stainless steel/aluminum alloy according to claim 17, wherein: the time interval from the completion of step 1.2 to the start of step 2.1 is less than 2 min.
19. The method of dissimilar metal brazing attachment of stainless steel/aluminum alloy according to claim 18, wherein: the specific method for carrying out impact current copper plating by adopting the copper plating bath solution in the step 2.1 comprises the following steps: the temperature of the copper plating bath is 15-35 ℃, the electroplating time is 2-4 min, and the aluminum alloy workpiece swings back and forth and rotates circumferentially in the impact process; the specific method for plating copper on the narrow and deep groove of the aluminum alloy flange plate by using the copper plating bath solution in the step 2.2 comprises the following steps: the temperature of the copper plating bath is 15-40 ℃, the electroplating time is 7-9 min, and the aluminum alloy workpiece swings back and forth and rotates circumferentially in the impact process.
20. The method of dissimilar metal brazing attachment of stainless steel/aluminum alloy according to claim 19, wherein: the bath solution for the primary and secondary copper plating is a copper cyanide solution.
21. The method of dissimilar metal brazing attachment of stainless steel/aluminum alloy according to claim 1, wherein: the tin bath is the annular, and the groove depth is 15 ~ 25mm, and the groove width is 3 ~ 10 mm.
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| CN111940862A (en) * | 2020-07-14 | 2020-11-17 | 首都航天机械有限公司 | Active brazing flux, metal oxide film removing method and tin coating method |
| CN116967648B (en) * | 2023-09-22 | 2023-12-19 | 淄博永晟精陶科技有限公司 | Silicon carbide pipe welding device |
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