CN117381127A - Welding method of heat exchanger and heat exchanger - Google Patents
Welding method of heat exchanger and heat exchanger Download PDFInfo
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- CN117381127A CN117381127A CN202311558574.6A CN202311558574A CN117381127A CN 117381127 A CN117381127 A CN 117381127A CN 202311558574 A CN202311558574 A CN 202311558574A CN 117381127 A CN117381127 A CN 117381127A
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- heat exchanger
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- 238000003466 welding Methods 0.000 title claims abstract description 142
- 238000000034 method Methods 0.000 title claims abstract description 81
- 238000009792 diffusion process Methods 0.000 claims abstract description 67
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 54
- 239000002356 single layer Substances 0.000 claims abstract description 35
- 229910052742 iron Inorganic materials 0.000 claims abstract description 27
- 230000008569 process Effects 0.000 claims abstract description 26
- 229910000570 Cupronickel Inorganic materials 0.000 claims abstract description 25
- 239000000463 material Substances 0.000 claims abstract description 24
- 229910052751 metal Inorganic materials 0.000 claims abstract description 15
- 239000002184 metal Substances 0.000 claims abstract description 15
- 230000000694 effects Effects 0.000 claims abstract description 13
- 238000010438 heat treatment Methods 0.000 claims description 20
- 238000005192 partition Methods 0.000 claims description 17
- 239000007787 solid Substances 0.000 claims description 11
- 238000005070 sampling Methods 0.000 claims description 10
- 238000009864 tensile test Methods 0.000 claims description 8
- 238000012360 testing method Methods 0.000 claims description 7
- 238000004321 preservation Methods 0.000 claims description 4
- 230000000630 rising effect Effects 0.000 claims description 4
- 238000001816 cooling Methods 0.000 claims description 3
- 230000000712 assembly Effects 0.000 claims 1
- 238000000429 assembly Methods 0.000 claims 1
- 238000005219 brazing Methods 0.000 abstract description 17
- 230000007797 corrosion Effects 0.000 abstract description 9
- 238000005260 corrosion Methods 0.000 abstract description 9
- 230000004907 flux Effects 0.000 abstract description 5
- 150000002739 metals Chemical class 0.000 abstract description 5
- 238000012545 processing Methods 0.000 abstract description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 6
- 230000001276 controlling effect Effects 0.000 description 4
- 239000000945 filler Substances 0.000 description 4
- 229910000679 solder Inorganic materials 0.000 description 4
- 229910052786 argon Inorganic materials 0.000 description 3
- 238000013461 design Methods 0.000 description 3
- 239000013535 sea water Substances 0.000 description 3
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000001788 irregular Effects 0.000 description 2
- 229910052748 manganese Inorganic materials 0.000 description 2
- 239000011572 manganese Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910002482 Cu–Ni Inorganic materials 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000003889 chemical engineering Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000036757 core body temperature Effects 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010612 desalination reaction Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 229910000765 intermetallic Inorganic materials 0.000 description 1
- 210000001503 joint Anatomy 0.000 description 1
- 239000010410 layer Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 229910002059 quaternary alloy Inorganic materials 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K20/00—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating
- B23K20/02—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating by means of a press ; Diffusion bonding
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K20/00—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating
- B23K20/002—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating specially adapted for particular articles or work
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D9/00—Heat-exchange apparatus having stationary plate-like or laminated conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
- F28D9/04—Heat-exchange apparatus having stationary plate-like or laminated conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being formed by spirally-wound plates or laminae
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F9/00—Casings; Header boxes; Auxiliary supports for elements; Auxiliary members within casings
- F28F9/26—Arrangements for connecting different sections of heat-exchange elements, e.g. of radiators
- F28F9/262—Arrangements for connecting different sections of heat-exchange elements, e.g. of radiators for radiators
- F28F9/268—Arrangements for connecting different sections of heat-exchange elements, e.g. of radiators for radiators by permanent joints, e.g. by welding
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Pressure Welding/Diffusion-Bonding (AREA)
Abstract
The invention discloses a welding method of a heat exchanger and the heat exchanger, wherein the welding method comprises the following steps: constructing a single-layer assembly; stacking the single-layer assembly between two end plates to form a heat exchanger core; performing diffusion welding on the heat exchanger core; in the diffusion welding process of the heat exchanger core, the deformation amount of each single-layer assembly is controlled. The invention is applied to the diffusion welding of iron white copper BFe10-1-1 material, has compact structure and high heat exchange efficiency, does not use brazing flux in the processing process, and ensures that atoms among metals are mutually diffused by adjusting certain temperature and pressure, thereby forming a whole. The heat exchanger has the advantages of good corrosion resistance, compact structure, small volume, good heat exchange performance and good pressure-bearing effect. The deformation of each single-layer component is controlled, and the application of the deformation to the single-layer component can effectively make up microscopic gaps among atoms, so that the atoms can be fully diffused.
Description
Technical Field
The invention relates to the technical field of heat exchangers, in particular to a heat exchanger welding method and a heat exchanger.
Background
At present, the diffusion welding heat exchanger is widely applied to the fields of energy, power, military, electronics, aerospace, hydrogen and the like, and plays a key role in medium heat exchange. The diffusion welding process needs to strongly squeeze the welding surfaces, and then the molecular diffusion movement between the welding surfaces is accelerated by heating, so that the high-strength combination is achieved. Diffusion welding is particularly suitable for the combination of dissimilar metal materials, heat-resistant alloys, new materials such as ceramics, intermetallic compounds, composite materials and the like, and has obvious advantages especially for materials which are difficult to weld by fusion welding methods.
BFe10-1-1 is iron white copper with less nickel, has good corrosion resistance to clean or polluted seawater and estuary water, and is widely used in heat exchangers using seawater in power stations, desalination, petrochemical plants and the like. The traditional iron copper-clad plate-fin heat exchanger is processed by adopting a brazing process, and certain brazing solder is added during welding to achieve adhesion among materials, but in the actual use process, the brazing solder is extremely easy to corrode by a medium, so that the whole service life of the heat exchanger is reduced.
Disclosure of Invention
Therefore, the technical problem to be solved by the invention is to overcome the defect that the whole service life of the heat exchanger is reduced because the existing iron white copper BFe10-1-1 heat exchanger can only be welded by a brazing or argon arc welding process, thereby providing a heat exchanger welding method and a heat exchanger.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
a method of welding a heat exchanger comprising the steps of:
welding the parts to construct a single-layer assembly;
stacking the single-layer assembly between two end plates to form a heat exchanger core body, and pre-fixing the periphery of the heat exchanger core body;
and performing diffusion welding on the heat exchanger core, wherein the method comprises the following process steps of:
heating the heat exchanger core to a first temperature and applying a first pressure to the heat exchanger core during a first period of time;
in a second time period, carrying out heat preservation and pressure maintaining on the heat exchanger core;
heating the heat exchanger core to a second temperature and applying a first pressure to the heat exchanger core during a third time period;
in a fourth time period, the heat exchanger core is insulated, and the heat exchanger core is pressurized in a staged manner;
cooling the heat exchanger core during a fifth time period while reducing the pressure applied by the heat exchanger core to a first pressure; when the temperature of the heat exchanger core is reduced to a third temperature, decompressing the heat exchanger core and taking out the heat exchanger core;
and controlling the deformation of each single-layer assembly in the diffusion welding process of the heat exchanger core body.
Further optimizing the technical scheme, wherein the heat exchanger is a iron white copper BFe10-1-1 heat exchanger; the parts comprise fins, side strips and partition plates made of iron white copper BFe10-1-1 material.
Further optimizing the technical scheme, the welding of the parts is performed to construct a single-layer assembly, and the method comprises the following steps:
the fin is placed on the surface of the baffle, two edge strips are respectively placed on two end faces parallel to the flow channels on the fin, and the fin, the baffle and the edge strips are welded and fixed in a resistance spot welding mode.
According to the technical scheme, the heat exchanger core is heated to the first temperature in a uniform heating mode.
Further optimizing the technical scheme, the method further comprises at least one of the following:
the first time period is 200min, the first temperature is 800 ℃, and the first pressure is 2MPa;
the second time period is 30min;
the third time period is 30min, and the second temperature is 940 ℃; heating the heat exchanger core to a second temperature at a heating rate of 4.6 ℃/min;
the fourth time period is 200min;
the fifth time period is 1min, and the third temperature is below 200 ℃.
Further optimizing the technical scheme, carrying out staged pressurization on the heat exchanger core body, and comprising the following steps:
continuing to stably maintain the first pressure during the sixth period;
uniformly increasing the pressure on the heat exchanger core to a second pressure during a seventh time period;
in the eighth time period, stably applying a second pressure to eliminate macroscopic gaps between materials, so that metal atoms can be mutually diffused;
uniformly increasing the pressure on the heat exchanger core to a third pressure during a ninth time period;
during the tenth period, the third pressure is steadily applied;
the sum of the sixth, seventh, eighth, ninth, and tenth time periods is equal to the fourth time period.
Further optimizing the technical scheme, the method further comprises at least one of the following:
the sixth time period is 30min;
the seventh time period is 10min, the second pressure is 10MPa, and the pressure rising rate for uniformly rising the pressure of the heat exchanger core to the second pressure is 0.8MPa/min;
the eighth time period is 120min;
the ninth time period is 10min, the third pressure is 16MPa, and the pressure of the heat exchanger core is uniformly increased to the third pressure, and the pressure increasing rate is 0.6MPa/min;
the tenth time period is 30 minutes.
According to the further optimized technical scheme, the deformation of each single-layer component is controlled to be between 0.08 and 0.15 mm.
Further optimizing the technical scheme, the method further comprises the step of testing welding performance:
respectively sampling from the fin position and the solid position of the heat exchanger core body formed by diffusion welding for tensile test;
judging the performance of the heat exchanger core body formed by diffusion welding according to the tensile test result;
when the fin sample is stretched, the fin sample is pulled off from the interface of the fin and the partition plate, and the section is flat; and/or the solid sample is directly broken when stretched, and plastic deformation does not occur; the diffusion welding effect of the heat exchanger core is proved to be poor;
when the fin sampling position is broken by stretching from the fin position and/or the solid sampling position is broken after plastic deformation, the welding effect of the heat exchanger core body is good.
A heat exchanger is obtained by the welding method of the heat exchanger.
The technical scheme of the invention has the following advantages:
1. the welding method of the heat exchanger is applied to diffusion welding of iron white copper BFe10-1-1 materials, has compact structure and high heat exchange efficiency, does not use brazing flux in the processing process, and ensures that atoms among metals are mutually diffused by adjusting certain temperature and pressure, thereby forming a whole. The heat exchanger has the advantages of good corrosion resistance, compact structure, small volume, good heat exchange performance and good pressure-bearing effect.
After each single-layer component is stacked, pre-welding is carried out, and then the heat exchanger core body is preliminarily fixed, so that the stability of the heat exchanger core body in the diffusion welding process can be ensured. In the diffusion welding process of the heat exchanger core, the deformation of each single-layer component is controlled, and the micro gaps among atoms can be effectively compensated by applying the deformation to the single-layer component, so that the atoms can be fully diffused, and the heat exchanger core is formed into a whole by diffusion welding.
2. According to the welding method of the heat exchanger, the iron white copper BFe10-1-1 material is welded by adopting atomic diffusion welding, and the temperature is firstly increased to the first temperature and kept for a period of time, then is increased to the second temperature and kept for a period of time, so that the temperature difference between the inside and the outside of the heat exchanger core body is prevented from being too large due to too fast temperature increase, and abnormal deformation caused by inconsistent expansion between the inside and the outside of the heat exchanger core body is avoided; in the process, the heat exchanger core is continuously pressurized, so that microscopic gaps between the fins and the partition plates as well as microscopic gaps between the partition plates and the edge strips can be continuously made up.
After the diffusion welding furnace is started, the heat exchanger core is heated to the first temperature in a uniform heating mode, so that the problem that the difference of the internal and external hardness of the material is large due to the fact that the heating speed is too high, and the difference of the internal and external hardness of the heat exchanger is small is solved.
3. According to the welding method for the heat exchanger, when the temperature is continuously increased, the pressure is regulated in a stepwise manner, and the pressure applied along with the time gradually increases, so that microscopic gaps on contact surfaces of the fins and the partition plates and contact surfaces of the partition plates and the edge strips can be effectively made up, metal atoms on the contact surfaces of the fins and the partition plates and the contact surfaces of the partition plates and the edge strips are mutually diffused in a high-temperature state, and finally the microscopic gaps are made up, so that the whole heat exchanger is formed.
4. The invention provides a welding method of a heat exchanger, which is characterized in that in the step of pressurizing a heat exchanger core body:
the pressure of the heat exchanger core is uniformly increased to the second pressure, the pressure increasing rate is 0.8MPa/min, the fins and the strakes can be guaranteed to deform slowly, and the heat exchanger core can be guaranteed to be tidy after diffusion welding. After the pressure of the heat exchanger core body is uniformly increased to the second pressure, the pressure stabilizing operation is carried out, so that the continuous compression of the fins, the partition plates, the strakes and the partition plates can be ensured, and macroscopic gaps among materials are eliminated, so that metal atoms can be mutually diffused. And then the pressure of the heat exchanger core body is uniformly increased to the third pressure and is stabilized for a period of time, so that the heat exchanger core body can meet the welding deformation requirement.
5. According to the welding method of the heat exchanger, the deformation rate of the heat exchanger core is low during welding, and the contact surface of the diffusion welded heat exchanger core fin and the partition plate is flat.
6. The welding method of the heat exchanger provided by the invention further comprises a method for testing welding performance, so that the performance of the welded heat exchanger can be verified in time, and further, the heat exchanger is produced according to parameters adopted by qualified products, and the production speed of the heat exchanger is increased.
7. According to the welding method of the heat exchanger, provided by the invention, before welding, the single-layer deformation requirement and the post-welding height requirement of the diffusion welding fin assembly are considered, the pre-welding height is fully considered, 4-8 limiting blocks are designed, and after the upper pressure head of the diffusion welding furnace is pressed to the limiting blocks, the upper pressure head of the diffusion welding furnace is not deformed downwards any more, so that the heat exchanger core body can meet the expected height requirement after being discharged from the furnace, and the deformation of each single-layer assembly is controlled.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is an exploded view of one embodiment of a heat exchanger core to be welded in accordance with the present invention;
FIG. 2 is a schematic diagram illustrating temperature control of an embodiment of a method of welding a heat exchanger provided by the present invention;
FIG. 3 is a schematic diagram illustrating pressure control of an embodiment of a method of welding a heat exchanger provided by the present invention;
FIG. 4 is a schematic illustration of one embodiment of a heat exchanger core to be welded in accordance with the present invention positioned within a diffusion welding furnace;
FIG. 5 is a drawing of a sample of the position of a fin in a tensile test after diffusion welding according to the present invention;
FIG. 6 is a drawing of a physical location sample of a tensile failure in the present invention after diffusion welding for tensile testing;
FIG. 7 is a graph showing the effect of one embodiment of a method of welding a heat exchanger according to the present invention in controlling the amount of single-layer deformation of a single-layer assembly;
FIG. 8 is a flow chart of a method of welding a heat exchanger provided by the present invention.
Reference numerals:
1. end plate, 2, fin, 3, strake, 4, baffle, 5, last pressure head, 6, stopper, 7, heat exchanger core, 8, lower pressure head.
Detailed Description
The following description of the embodiments of the present invention will be made apparent and fully in view of the accompanying drawings, in which some, but not all embodiments of the invention are shown. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. The term "front side" refers to the upper surface of the heat exchanger plate and the term "back side" refers to the lower surface of the heat exchanger plate. Furthermore, the terms "first," second, "" third, "" fourth, "and fifth" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
In addition, the technical features of the different embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
The iron white copper BFe10-1-1 is a quaternary alloy obtained by adding a small amount of elements such as iron, manganese and the like into a Cu-Ni alloy. The addition of iron and manganese elements can raise the corrosion resistance and mechanical performance of cupronickel, but the addition amount must not exceed 2% so as to prevent corrosion and cracking. The iron white copper BFe10-1-1 has the characteristics of high strength, good corrosion resistance and particularly strong corrosion capability to seawater. Therefore, the heat exchanger can be widely applied to condensing pipes and heat exchanger pipes in chemical engineering and ocean engineering.
The heat exchange performance of the traditional double pipe heat exchanger is low, and a large volume is usually required to meet the heat exchange performance. The brazing is to adhere the metals together by using the brazing filler metal, pressurization is not needed, and only the brazing filler metal is required to be melted and cooled, so that the brazing filler metal is simpler, and is essentially the melting welding of the brazing filler metal. Diffusion welding is a process of mutually diffusing atoms through high temperature and high pressure, so that the requirement on the surface quality of materials is high. The iron white copper material is relatively soft, the iron white copper material is easy to deform under high temperature pressurization, and the temperature and pressure curves are difficult to control, so that the traditional iron white copper plate-fin heat exchanger is processed by adopting a brazing process and an argon arc welding process. During welding, certain brazing solder is added to achieve adhesion among materials, but in the actual use process, the brazing solder is extremely easy to corrode by a medium, so that the service life of the whole heat exchanger is reduced.
The invention adopts a diffusion welding mode to weld the iron white copper BFe10-1-1 material, and further does not use brazing flux in the processing process.
Specific embodiments of the present invention will be described in detail below in connection with the welding method of the heat exchanger of the first aspect of the present invention and the heat exchanger of the second aspect.
It should be noted that, the welding method of the heat exchanger according to the first aspect of the present invention is only a preferred embodiment of the present invention, the heat exchanger according to the present invention may be manufactured by the welding method of the heat exchanger according to the first aspect of the present invention, or may be manufactured by other methods, and for convenience of explanation, a specific welding process of the heat exchanger according to the present invention is described below by the welding method of the heat exchanger according to the first aspect of the present invention.
Referring to fig. 1 to 8, a method for welding a heat exchanger includes the steps of:
s1, welding parts to construct a single-layer assembly.
S2, stacking the single-layer assembly between the two end plates 1 to form a heat exchanger core body, and pre-fixing the periphery of the heat exchanger core body.
S3, placing the pre-welded heat exchanger core body in a diffusion welding furnace for diffusion welding, wherein the method comprises the following steps of:
heating the heat exchanger core to a first temperature and applying a first pressure to the heat exchanger core during a first period of time;
in a second time period, heat preservation and pressure maintaining are carried out on the heat exchanger core body;
heating the heat exchanger core to a second temperature and applying a first pressure to the heat exchanger core during a third time period;
in a fourth time period, heat preservation is carried out on the heat exchanger core body, and staged pressurization is carried out on the heat exchanger core body;
cooling the heat exchanger core during a fifth time period while reducing the pressure applied by the heat exchanger core to a first pressure; and when the temperature of the heat exchanger core is reduced to the third temperature, decompressing the heat exchanger core and taking out the heat exchanger core.
S4, controlling the deformation of each single-layer component in the diffusion welding process of the heat exchanger core.
Because no method for directly utilizing the iron white copper BFe10-1-1 material to be diffusion welded into the heat exchanger exists at present, the invention provides a welding method of the heat exchanger. The welding method of the heat exchanger is applied to diffusion welding of iron white copper BFe10-1-1 materials, is particularly suitable for diffusion welding between iron white copper plates and plate fin heat exchangers, does not use brazing flux in the processing process, and enables atoms among metals to diffuse mutually by adjusting certain temperature and pressure, so that a whole is formed. The heat exchanger has the advantages of good corrosion resistance, compact structure, small volume, good heat exchange performance and good pressure-bearing effect.
In step S1, the fins 2, the side bars 3, and the separators 4 to be diffusion-welded, which constitute the heat exchanger, are welded and fixed in a single-layer assembly by means of resistance spot welding. The step S1 specifically comprises the following steps: the fin 2 is placed on the surface of the baffle plate 4, two edge strips 3 are respectively placed on two end faces parallel to the flow channel on the fin 2, and the fin 2, the baffle plate 4 and the edge strips 3 are welded and fixed in a resistance spot welding mode.
In step S2, the single-layer assembly is clamped on a fixed tool, and the stacking height is more than or equal to 30mm, so that the heat exchanger core is formed. And pre-welding and fixing the periphery of the heat exchanger core to be welded by using a laser welding or argon arc welding process.
As a specific embodiment, as shown in fig. 2 and 3, step S3 specifically includes the following steps:
s31, starting the diffusion welding furnace, and uniformly heating the heat exchanger core body from normal temperature to 800 ℃ within 200min in order to avoid the fact that the temperature difference between the inside and the outside of the heat exchanger is too high to cause the large difference between the hardness of the inside and the hardness of the material. In order to avoid the deformation of the channels caused by irregular expansion of the heat exchanger core body due to heating, the heat exchanger core body is continuously pressurized for 2MPa and maintained in the process.
S32, after the temperature is raised to 800 ℃, the heat is preserved for about 30 minutes, so that the heat exchanger core body can be fully heated, and the core body temperature is consistent with the surface temperature, in order to enable the fins 2 and the partition plates 4 to be welded in a pre-diffusion way, the macroscopic gaps among materials are made up, and meanwhile, in order that the fins cannot be deformed by pressure, the heat exchanger core body is continuously pressurized for 2MPa and maintained in the process.
S33, in order to enable BFe10-1-1 metal atoms in the heat exchanger to be sufficiently active and meet the requirement of diffusion welding among atoms, the temperature in the furnace is uniformly increased to 940 ℃ for 30min, and the heating rate is about 4.6 ℃/min. At the same time, in order to avoid the deformation of the channels caused by irregular expansion generated by heating the heat exchanger core, and to enable preliminary pre-welding, the heat exchanger core is continuously pressurized to 2MPa and maintained in the process.
S34, maintaining at 940 ℃ for about 200min, and pressurizing the heat exchanger core in a stepwise manner:
continuing to stably maintain the pressure of about 2MPa for 0-30 min;
in the 30 th to 40 th minutes, the pressure is uniformly increased to 10MPa, in order to ensure that the fins and the strakes can be deformed slowly, the heat exchanger core body can ensure that the channels are tidy after diffusion welding, and the pressure increasing rate is 0.8MPa/min;
in 40-160min, a pressure of about 10MPa is stably applied to ensure that the fins and the separator and the strakes and the separator are continuously pressed so as to eliminate macroscopic gaps among materials and enable metal atoms to be mutually diffused;
uniformly raising the pressure to 16MPa in 160-170min, wherein the raising speed is 0.6MPa/min;
and (3) stably applying pressure of about 16MPa within 170-200min, so as to ensure that the heat exchanger core body can meet the welding deformation requirement.
After the procedure is finished, the pressure is reduced to 2MPa within 1min, the pressure is kept, the heat exchanger core is cooled along with the furnace until the temperature is reduced to below 200 ℃, and then the pressure is relieved and the core is taken out.
In step S4, in order to enable diffusion welding to be completed, the heat exchanger core is free from leakage and can withstand a certain pressure, and it is necessary to control the single-layer deformation amount of the single-layer assembly to be between 0.08 and 0.15 mm. As shown in fig. 7, the initial contact is in the form of irregularities, and when a deformation amount is applied to the single-layer assembly, deformation and interface are formed, and then grain boundary migration, micropore removal, and finally volume diffusion and micropore removal are performed. Therefore, the deformation of the single-layer assembly can effectively compensate microscopic gaps among atoms, so that the atoms can be fully diffused, and the heat exchanger core body is formed into a whole through diffusion welding.
It should be noted that the welded plate-fin heat exchanger of the present invention is different from the microchannel heat exchanger.
In a first aspect, the welding temperature of the stainless steel-based microchannel structured heat exchanger is typically above 1000 ℃, while the diffusion welding temperature of the plate-fin structured heat exchanger of the present invention is 940 ℃. After the iron white copper is heated to above 1000 ℃, the material can become very soft, and the iron white copper is easy to deform and collapse under high-temperature pressurization. Therefore, the maximum diffusion welding temperature of the plate-fin heat exchanger is controlled to 940 ℃, and the plate-fin heat exchanger can meet the welding requirement of iron white copper.
In the second aspect, the micro-channel structure needs to be depressurized after being pressurized for a period of time due to the specificity of the channels, so that the stress between the channels is released, the flatness of the plates can be ensured, and the gaps between the plates are made up. The design deformation of the plate-fin structure heat exchanger is between 0.08 and 0.15mm (the test result shows that after the single-layer deformation of the plate-fin structure is 0.02mm, the pressure bearing performance is poor), and the heat exchanger has enough deformation to make up the gaps among components. Therefore, in step S34, when the heat exchanger core is pressurized stepwise, the pressure does not need to be released and the pressure is increased. The time required for diffusion welding is increased because the pressure is re-increased after the depressurization. The invention does not reduce pressure in the process of pressurizing the heat exchanger core in a stepwise manner, thereby saving a large amount of diffusion welding time and reducing production cost.
In the third aspect, the diffusion welding temperature is different from the pressure matching, and in the diffusion welding, it is required that the product is continuously and slowly deformed in a high-temperature and high-pressure state. Slight pressure and temperature mismatch can result in the product being directly compressed to the final height, resulting in the product not being continuously pressurized and thus affecting interatomic diffusion. Because the product of the invention is in an isostatic state in a diffusion welding furnace, when the product is pressurized, the pressure applied to each single-layer assembly is the same, and the deformation rate is consistent theoretically. It should be noted that, the control point of the deformation of the single-layer component in the invention is that the product obtains an original height through calculation before diffusion welding, and then designs the height of the limiting block, so that the height reaches the design requirement height after the diffusion welding is completed, the original height subtracts the post-welding height, and then divides the number of layers to calculate the required deformation of the single-layer component.
According to the welding method of the heat exchanger, the heat exchanger core body formed by diffusion welding can achieve the pressure bearing performance of more than 5MPa, and the pressure bearing requirement of most heat exchangers is met.
The diffusion welding parameters of the welding method of the heat exchanger can effectively weld the plate-fin structure made of the iron white copper BFe10-1-1 material and the butt joint welding between the plates. The plate-fin heat exchanger core body formed by diffusion welding can bear the water pressure of 5MPa, and can meet the pressure-bearing requirement under the working condition of multiple pressures.
The welding method of the heat exchanger further comprises the step of testing welding performance:
and respectively sampling the fin position and the solid position of the heat exchanger core body formed by diffusion welding for tensile test. It should be noted that, the solid position refers to a position without fins, for example, four corners in fig. 1 are solid areas.
And judging the performance of the heat exchanger core body formed by diffusion welding according to the tensile test result. When the fin sample is stretched, the fin sample is pulled off from the interface of the fin and the partition plate, and the section is flat; and/or the solid sample is directly broken when stretched, and plastic deformation does not occur; the diffusion welding effect of the heat exchanger core proves to be poor. When the fin sampling position is broken by stretching from the fin position and/or the solid sampling position is broken after plastic deformation, the welding effect of the heat exchanger core body is good.
Fig. 5 is a drawing of a drawing fracture at a sampling position of a fin, which is a physical drawing of the fin sample when an actual drawing test is performed, and from the drawing, it can be seen that the invention is fracture at the fin position, which shows that the connection strength of the fin and a separator plate is very high after diffusion welding of a heat exchanger, and the welding effect is very good.
Fig. 6 is a drawing of a drawing fracture at a physical location sample, which is a physical drawing of a physical sample when an actual drawing test is performed, from which it can be seen that plastic deformation occurs at the physical sample of the present invention, indicating that the welding effect is good.
As a further improved implementation mode, in order to enable the height of the heat exchanger core body to be controllable after diffusion welding is completed, as shown in fig. 4, 4-8 limiting blocks 6 are arranged around the upper pressure head 5 and the lower pressure head 8, when the upper pressure head 5 is pressed down to the limiting blocks 6, the upper pressure head 5 cannot continuously move downwards again because the pressure bearing performance of the limiting blocks 6 is far greater than that of the heat exchanger, and therefore the purpose of controlling the height of the heat exchanger core body 7 after diffusion welding is achieved. Specifically, the layout mode of the limiting blocks can be determined according to the actual placement condition of the heat exchanger core.
A heat exchanger obtainable by the method of welding a heat exchanger according to the first aspect of the invention. The heat exchanger in the embodiment is an iron white copper BFe10-1-1 heat exchanger, and a diffusion welding method is provided for the iron white copper BFe10-1-1 material to be diffusion welded into the heat exchanger, and brazing flux is not used in the processing process, and atoms among metals are mutually diffused by adjusting certain temperature and pressure, so that a whole is formed. The heat exchanger has the advantages of good corrosion resistance, compact structure, small volume, good heat exchange performance and good pressure-bearing effect.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. And obvious variations or modifications thereof are contemplated as falling within the scope of the present invention.
Claims (10)
1. A method of welding a heat exchanger, comprising the steps of:
welding the parts to construct a single-layer assembly;
stacking the single-layer assembly between two end plates (1) to form a heat exchanger core body, and pre-fixing the periphery of the heat exchanger core body;
and performing diffusion welding on the heat exchanger core, wherein the method comprises the following process steps of:
heating the heat exchanger core to a first temperature and applying a first pressure to the heat exchanger core during a first period of time;
in a second time period, carrying out heat preservation and pressure maintaining on the heat exchanger core;
heating the heat exchanger core to a second temperature and applying a first pressure to the heat exchanger core during a third time period;
in a fourth time period, the heat exchanger core is insulated, and the heat exchanger core is pressurized in a staged manner;
cooling the heat exchanger core during a fifth time period while reducing the pressure applied by the heat exchanger core to a first pressure; when the temperature of the heat exchanger core is reduced to a third temperature, decompressing the heat exchanger core and taking out the heat exchanger core;
and controlling the deformation of each single-layer assembly in the diffusion welding process of the heat exchanger core body.
2. The method of welding a heat exchanger according to claim 1, wherein the heat exchanger is a iron white copper BFe10-1-1 heat exchanger; the parts comprise fins (2), side strips (3) and a partition plate (4) which are made of iron white copper BFe 10-1-1.
3. The method of welding a heat exchanger according to claim 2, wherein the welding the parts to construct a single layer assembly comprises the steps of:
the fin (2) is placed on the surface of the partition plate (4), two side strips (3) are respectively placed on two end faces parallel to the flow channel on the fin (2), and the fin (2), the partition plate (4) and the side strips (3) are welded and fixed in a resistance spot welding mode.
4. The method of welding a heat exchanger according to claim 1, wherein the means for heating the heat exchanger core to the first temperature is a means for uniformly heating.
5. The method of welding a heat exchanger of claim 1, further comprising at least one of:
the first time period is 200min, the first temperature is 800 ℃, and the first pressure is 2MPa;
the second time period is 30min;
the third time period is 30min, and the second temperature is 940 ℃; heating the heat exchanger core to a second temperature at a heating rate of 4.6 ℃/min;
the fourth time period is 200min;
the fifth time period is 1min, and the third temperature is below 200 ℃.
6. The method of welding a heat exchanger according to claim 1, wherein the heat exchanger core is pressurized in stages, comprising the steps of:
continuing to stably maintain the first pressure during the sixth period;
uniformly increasing the pressure on the heat exchanger core to a second pressure during a seventh time period;
in the eighth time period, stably applying a second pressure to eliminate macroscopic gaps between materials, so that metal atoms can be mutually diffused;
uniformly increasing the pressure on the heat exchanger core to a third pressure during a ninth time period;
during the tenth period, the third pressure is steadily applied;
the sum of the sixth, seventh, eighth, ninth, and tenth time periods is equal to the fourth time period.
7. The method of welding a heat exchanger of claim 6, further comprising at least one of:
the sixth time period is 30min;
the seventh time period is 10min, the second pressure is 10MPa, and the pressure rising rate for uniformly rising the pressure of the heat exchanger core to the second pressure is 0.8MPa/min;
the eighth time period is 120min;
the ninth time period is 10min, the third pressure is 16MPa, and the pressure of the heat exchanger core is uniformly increased to the third pressure, and the pressure increasing rate is 0.6MPa/min;
the tenth time period is 30 minutes.
8. The method of welding a heat exchanger according to claim 1, wherein the deformation amount of each of the single-layer assemblies is controlled to be between 0.08 and 0.15 mm.
9. The method of welding a heat exchanger according to any one of claims 2 to 8, further comprising the step of testing welding performance:
respectively sampling from the fin position and the solid position of the heat exchanger core body formed by diffusion welding for tensile test;
judging the performance of the heat exchanger core body formed by diffusion welding according to the tensile test result;
when the fin sample is stretched, the fin sample is pulled off from the interface of the fin and the partition plate, and the section is flat; and/or the solid sample is directly broken when stretched, and plastic deformation does not occur; the diffusion welding effect of the heat exchanger core is proved to be poor;
when the fin sampling position is broken by stretching from the fin position and/or the solid sampling position is broken after plastic deformation, the welding effect of the heat exchanger core body is good.
10. A heat exchanger, characterized in that it is obtained by means of a welding method of a heat exchanger according to any one of claims 1-9.
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| CN202311558574.6A CN117381127A (en) | 2023-11-21 | 2023-11-21 | Welding method of heat exchanger and heat exchanger |
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| CN202311558574.6A CN117381127A (en) | 2023-11-21 | 2023-11-21 | Welding method of heat exchanger and heat exchanger |
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