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WO2024084777A1 - Matériau de brasage produit par moulage d'une poudre métallique, et procédé de traitement de brasage dans la production d'un échangeur thermique de type à tubes à ailettes l'utilisant - Google Patents

Matériau de brasage produit par moulage d'une poudre métallique, et procédé de traitement de brasage dans la production d'un échangeur thermique de type à tubes à ailettes l'utilisant Download PDF

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Publication number
WO2024084777A1
WO2024084777A1 PCT/JP2023/028420 JP2023028420W WO2024084777A1 WO 2024084777 A1 WO2024084777 A1 WO 2024084777A1 JP 2023028420 W JP2023028420 W JP 2023028420W WO 2024084777 A1 WO2024084777 A1 WO 2024084777A1
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WO
WIPO (PCT)
Prior art keywords
brazing material
brazing
metal powder
tube
fin
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2023/028420
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English (en)
Japanese (ja)
Inventor
佳克 山本
等 多々良
淳平 鈴木
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Neis Co Ltd
Original Assignee
Neis Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP2022166042A external-priority patent/JP2025179273A/ja
Application filed by Neis Co Ltd filed Critical Neis Co Ltd
Publication of WO2024084777A1 publication Critical patent/WO2024084777A1/fr
Priority to JP2024566803A priority Critical patent/JP7726569B2/ja
Priority to PCT/JP2024/026963 priority patent/WO2025028483A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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
    • B23K1/00—Soldering, e.g. brazing, or unsoldering
    • 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
    • B23K1/00—Soldering, e.g. brazing, or unsoldering
    • B23K1/14—Soldering, e.g. brazing, or unsoldering specially adapted for soldering seams
    • 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
    • B23K3/00—Tools, devices, or special appurtenances for soldering, e.g. brazing, or unsoldering, not specially adapted for particular methods
    • B23K3/06—Solder feeding devices; Solder melting pans
    • 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
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/02—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape
    • B23K35/0205—Non-consumable electrodes; C-electrodes
    • 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
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
    • B23K35/24—Selection of soldering or welding materials proper
    • B23K35/30—Selection of soldering or welding materials proper with the principal constituent melting at less than 1550 degrees C
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C19/00—Alloys based on nickel or cobalt
    • C22C19/03—Alloys based on nickel or cobalt based on nickel
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C19/00—Alloys based on nickel or cobalt
    • C22C19/03—Alloys based on nickel or cobalt based on nickel
    • C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium

Definitions

  • the present invention relates to a brazing material.
  • the present invention also relates to a brazing method in the manufacture of a fin-tube heat exchanger using the brazing material of the present invention.
  • a fin-tube heat exchanger is a structure that has a tube that penetrates a heat sink made of multiple multi-layered fins made of metal, ceramic, etc., and the fins and tube are joined by brazing.
  • brazing materials are made of metals suitable for brazing, such as copper or copper alloys, aluminum or aluminum alloys, nickel or nickel alloys, and may contain trace elements. Their melting points are 450 degrees or higher, and when heat is applied to them, they melt when the temperature reaches the melting point or higher, and solidify when the temperature falls below the melting point. Some brazing materials contain flux as a solvent. As conventional brazing material compacts, two types are known: a bar-shaped brazing material which is a metal block; and a paste-like brazing material which contains powdered metal and has flowability.
  • the first compact, the rod-shaped brazing material is a metal ingot made by melting and sintering the metal material. It is often provided as a rod with a rectangular or circular cross-sectional shape.
  • the metal is melted and sintered, and the so-called packing ratio (the ratio of apparent density to true density) is 95% to 100%, making it dense and dense.
  • metal blocks contain metal oxides.
  • flux and solvent may be included in the brazing material of the metal block. The flux and solvent are not molten and widely dispersed in the metal, but are scattered in the metal block as small lumps of flux and solvent.
  • the filling rate of the entire compact varies depending on the volume of the binder and solvent, but the filling rate of the metal block other than the small lumps of flux and solvent is 95% to 100%, and it is still high density.
  • binders including mixtures of polymeric materials such as polymethacrylic acid, polyacrylic acid, polymethacrylic acid esters, and polyacrylic acid esters with ethers, esters, alcohols, and water that dissolve these materials.
  • This first formed body, a rod-shaped metal brazing material has been used for a long time and is relatively inexpensive to procure, but it also has many disadvantages.
  • the metal block is solidified into a rod shape, it can be difficult to accurately abut a thick, straight rod-shaped metal block brazing material against narrow brazing points or non-linear, curved brazing points, and the work can take time.
  • the brazing metal is melted during the molding process and then sintered to form a dense structure, the brazing heat is only directly input to the outer surface, and the specific surface area is not large, so heat diffusion to the internal metal occurs through thermal conduction, and the heat input efficiency cannot be said to be good.
  • the second molded product contains the metal to be the brazing base material in the form of metal powder, and is kneaded with a binder to create a paste-like material with high viscosity and fluidity.
  • Silver brazing paste containing flux is widely used. As it is a paste-like material with fluidity, it can be squeezed out in a fixed amount with a dispenser, and is widely used for brazing. It is also convenient for application to flat substrates by screen printing. Additionally, brazing materials such as nickel alloys, which have been attracting attention in recent years, are hard and difficult to process, so a technology has been developed in which the powder is made by atomizing the material, mixed with a binder, and used in the form of a paste.
  • This paste-like brazing material which is the second molded body, is relatively easy to handle since it can be simply squeezed out of a dispenser and applied to the area to be brazed, but it also has many disadvantages.
  • there are disadvantages such as the brazing material remaining on the moving trace, which mars the aesthetic appearance and causes brazing material loss.
  • a paste-like brazing material after the paste spreads over the brazing points, a process is required to evaporate and dry the binder, etc., which is time-consuming and costly.
  • finned-tube heat exchanger used in water heaters and the like are a combination of fins, which act as heat radiators, and tubes, which act as heat transfer tubes through which a heat medium circulates.
  • FIG. 10 is a diagram simply illustrating the configuration of a fin-tube heat exchanger that is the subject of brazing treatment using a brazing material according to the prior art.
  • Fig. 10(a) is a perspective view of the fin 10 viewed from a slight angle with the surface of the fin 10 through which the tube 20 is inserted facing the front
  • Fig. 10(b) is a longitudinal cross-sectional view taken along the longitudinal centerline of the fin 10 with the surface of the fin 10 through which the tube 20 is inserted facing the front.
  • the cross-sectional view is taken vertically through the center of the tube 20 and a groove 14 (described later).
  • the longitudinal cross-section in Fig. 10(b) is shown hatched.
  • the multi-layered fin 10 has a plurality of heat dissipating fins 11 stacked at a predetermined interval, each of which has a tube through hole 12 penetrating through it, and a tube 20 is inserted through the tube through hole 12 .
  • the fins 10 which are heat sinks, are made by pressing a thin metal plate to form tube insertion holes and then cutting the plate to a specified size.
  • the tube insertion holes are provided to match the outer shape of the tubes. They may be circular or flat.
  • stainless steel and copper alloy materials are often used because of their moldability, heat transfer properties, and light weight.
  • a fin tube heat exchanger is configured by stacking a predetermined number of fin materials (e.g., several hundred sheets) at a predetermined interval (e.g., several millimeters) according to the dimensions of the heat exchanger, and arranging the fins 10 in multiple layers.
  • the tube 20 is a heat transfer tube through which the heat medium circulates, and is a hollow tube in which the heat medium in liquid or gaseous form circulates.
  • heat transferability, workability, and corrosion resistance SUS, copper, or copper alloy tubes are often used as the material for the tube 20.
  • a curved pipe section is often fitted into the end portion to provide a so-called U-shaped folded curved section. As shown in FIG. 10, tubes that serve as heat transfer tubes are inserted into tube through holes formed in the overlapping of the multi-layered fins 10.
  • a tool called a billet which expands the inner diameter of the tube, may be inserted into the end of the tube 20 to enlarge the outer diameter of the tube slightly in proportion to the outer diameter, thereby expanding the diameter of the tube and bringing the outer edge of the tube into close contact with the inner edge of the tube through hole in the fin material.
  • the outer periphery of the tube is joined to the inner periphery of the tube through-hole of the fin by brazing.
  • the heat dissipating fins 11 of the multi-layered fins 10 are stacked together with very narrow gaps between them, it is not possible to directly insert the bar-shaped brazing material 30a made of a metal block into the inside.
  • the area to be brazed is the abutment area 13 between the outer peripheral edge of the tube 20 inside the multi-layered fin 10 and the inner peripheral edge of the tube through hole 12 of each heat dissipation fin 11.
  • FIG. 11 is a diagram showing a case where a bar-shaped brazing material 30a made of a metal block is used in the prior art.
  • 11(a) and 11(b) show an example in which a bar-shaped brazing material 30a made of a metal block is placed in the groove 14. Since it is a hard bar-shaped member, it is placed along the linear groove 14.
  • FIGS. 11(c) and 11(d) are diagrams showing the case where a paste-like brazing material 30b used in the prior art is used.
  • a paste-like brazing material 30 is applied in a pile in the groove 14 using a dispenser (not shown).
  • the portion to be brazed is the abutment portion 13 between the tube 20 and the tube through hole 12 inside the multi-layered fin 11, and since it is difficult to insert a dispenser into the narrow width of the fin 11, it remains difficult to directly access the abutment portion 13. Therefore, the paste-like brazing material 30b squeezed out from a dispenser (not shown) is applied to the groove 14 in a piled manner.
  • FIG. 12C is a diagram illustrating the gaps in the fins 10 in an enlarged manner to clearly show the state occurring in the gaps in the fins 10, focusing on the vicinity of the joints 13.
  • the brazing material that melted and traveled down the surface of the fins 10 by capillary action left traces and reached the joints 13, causing the "wetting" to spread at the joints 13, thereby carrying out the brazing process.
  • the problem with the brazing material 30 of the prior art is that it can be applied to locations that are easily accessible from the outside, but is difficult to apply to locations that are difficult to access.
  • the same is true for the fluid paste-like brazing material 30b.
  • the brazing process must be performed by applying a large amount of the paste brazing material 30b near the brazing point, inputting heat, and conducting and flowing the molten brazing material into the brazing point.
  • a typical example is the joining of the fins 11 and the tubes 20 in the finned tube heat exchanger 10.
  • the brazing points 14 of the finned tube heat exchanger 10 are located inside the narrow gaps between the many closely stacked fins 11 as described above, and therefore are difficult to access from the outside. Therefore, in order to use the conventional paste-like brazing material 30b, it is necessary to apply a large amount of the paste-like brazing material 30b to the outer edge side of the fin and then input heat so that the molten solder flows along the plane of the fin and into the through hole on the inside of the fin.
  • the paste-like brazing material 30b of the prior art and the brazing method using it have the following problems.
  • the first problem is that as the brazing filler metal flows to the brazing point, in some places the heat is radiated rather than being conducted by the metal, resulting in a decrease in the heat input efficiency during the brazing process or in poor brazing.
  • the second problem is that the brazing material flows over the flat surfaces of the fins 11 and remains attached to the surfaces of the fins 11, resulting in a large loss of brazing material and impairing the aesthetic appearance.
  • the third problem is that the brazing material that melts and flows on the surfaces of the fins 11 blocks the heat dissipation space or heat reception space between the fins 11 and the atmosphere, reducing the heat exchange efficiency on the surfaces of the fins 11.
  • the inventors have considered ways to improve the joining of the fin-tube heat exchanger 10 by using the conventional brazing material 30a in the form of a metal block instead of the conventional paste-like brazing material 30b, and have devised the configuration shown in Fig. 13.
  • they have also found that there are still problems to be solved.
  • the configuration proposed by the present inventors and shown in FIG. 13 will be described below, followed by an explanation of the problems that remain in this method.
  • Fig. 13 is a diagram showing an example of the structure of a new fin-tube heat exchanger invented by the present inventors.
  • the example shown in Fig. 13 is a new example of the structure invented by the present inventors, and is not known in the prior art, nor is there any publicly known literature.
  • the brazing point is not a groove on the outer periphery of the fin, but a separate groove is provided immediately above the tube through-hole, which is the brazing point.
  • the groove is provided as a depression that is connected to the tube through-hole and is integrated with it.
  • FIG. 14 is a diagram showing a brazing process assumed in the new fin-tube heat exchanger proposed by the present inventors and having the configuration shown in FIG.
  • a conventional brazing material made of a metal block is inserted through the groove provided adjacent to the tube through-hole and set in place.
  • heat is applied to the conventional brazing material made of a metal block, the brazing material is melted by the application of heat, and the molten brazing material is transported along the fin surface to the joint in the center by capillary action, and the wetting is spread at the joint 13, thereby performing a wetting process.
  • the brazing processing method for a fin tube heat exchanger shown in Figure 14 has the advantage of being able to improve all of the first, second, and third problems that were issues with the brazing method of the conventional technology described above.
  • the first problem of a decrease in the efficiency of heat input as radiant heat can be solved because there is no process of heat flowing between the fins, so there is basically no need to rely on radiant heat from the fin surface.
  • the second problem of brazing material being wasted and spoiling the appearance is also solved, because the groove and the brazing point are adjacent to each other, there is no process of the brazing material flowing over the surface of the fin, and the problem of brazing material being wasted and spoiling the appearance is also solved.
  • the third problem in which the brazing material blocks the heat dissipation space between the fins and the atmosphere, reducing the heat exchange efficiency on the surface of the fins, can be solved because the grooves and the brazing points are adjacent to each other, so the space between the fins is not filled or blocked by the brazing material.
  • the brazing method proposed by the inventors above is a significant improvement over the brazing method for conventional fin-tube heat exchangers and is highly evaluated.
  • the room for improvement is the problem of thermal efficiency caused by the rod-shaped brazing material made of metal.
  • the rod-shaped brazing material of the metal block is formed hard, so the filling rate is high and it can be said that the thermal conductivity is high.
  • heat can only be input from the end of the rod, and the heat input area is small compared to the total surface area of the brazing material, so it must be said that the heat input efficiency is actually low.
  • the thermal conductivity is high, it starts to melt from the surface, so it takes time for heat to enter the inside. There is room for improvement here.
  • the time of thermal conduction differs between the peripheral part close to the end and the central part far from the end, resulting in a large variation in temperature and an uneven melting state of the brazing material 30a. If the brazing material 30a melts first in the peripheral part close to the end, if the material in the central part far from the end remains in a metal block state, it may become necessary to rely on radiant heat from the surroundings for melting. There is also room for improvement here.
  • Fig. 15 is a diagram showing the technique disclosed in Japanese Patent Application Laid-Open No. 55-92288 in the prior art.
  • the technique disclosed in Japanese Patent Application Laid-Open No. 55-92288 uses a special metal tube, and fills the metal tube with brazing material in the form of metal powder.
  • This metal tube uses a metal material that has a higher melting point than the brazing material and does not dissolve when a wetting process is performed.
  • This metal tube has a slit, and the brazing material inside is dissolved and supplied through the slit.
  • JP-A-55-92288 has problems.
  • the first problem is that it is difficult to secure the amount of brazing material used.
  • the slit width cannot be made too large in order to fill the inside with metal powder, so the brazing material that melts due to heat input remains in the metal tube due to surface tension and capillary action.
  • the technology disclosed in JP-A-55-92288 is applied to the inside of an automobile cam, and after the brazing process, the metal tube is left behind to serve as an oil supply path, and it is believed that the metal tube has a high melting point.
  • the second problem is that the brazing process cannot be performed uniformly depending on the direction of the slits.
  • the metal tube remains and the brazing material leaks only from the slits, so the brazing material does not leak in all directions, and there is a problem that the brazing process cannot be performed uniformly depending on the direction of the slits.
  • the present invention aims to provide a brazing material which is a new third molded body, so to speak, different from the brazing material 30a which is a rod-shaped metal block which is the first molded body of the conventional brazing material, and the paste-like brazing material 30b which is the second molded body.
  • Another object of the present invention is to provide an effective method for improving the brazing of fin-tube heat exchangers, which have traditionally posed many problems, by using the brazing material of the present invention, which is the new third formed body.
  • the brazing material of the present invention is a brazing material obtained by compacting a metal powder made by powdering a metal to be used as a brazing material into a predetermined shape without melting the powder. Due to the above-mentioned structure, the brazing material of the present invention has a very large heat input area. In other words, in the case of the brazing material made of a metal block of the prior art, the heat input area is limited to the outer surface of the metal block, whereas in the brazing material made of molded metal powder of the present invention, the total area of the outer surfaces of the individual metal powders is the heat input area, so the specific surface area is very large and the heat input efficiency is greatly improved.
  • the brazing material of the metal block of the prior art is immersed and heat is applied as a single crystal like rock candy, and it gradually melts from its outer surface
  • the brazing material molded from metal powder of the present invention is a molded block of powdered sucrose with an appropriate particle size like a sugar cube, and can melt instantly when immersed in hot water and heat is applied. This is because the area that can receive heat is the sum of the outer surfaces of each powder.
  • the brazing material produced by molding the metal powder of the present invention may contain an organic binder in addition to the metal powder. It is ideal to use a binderless material, but the use of an organic binder improves the molding condition and also makes it possible to reduce the metal oxide, which is the metal powder.
  • the particle size range of the metal powder is 20 to 75 ⁇ m, which accounts for 90% or more, and that the packing rate of the metal powder (the ratio of apparent density to true density) is in the range of 50% to 80%.
  • the particle size range of the metal powder can be set as above because a certain particle size allows for fast melting and a good molten state.
  • the filling rate of the metal powder can be set as above because if it is too low, it becomes difficult to maintain the molded state, and if it is too high, the improvement in heat input efficiency, which is the technical effect of the present invention, decreases.
  • the metal in the brazing material produced by molding the metal powder of the present invention, can be any one of nickel alloy, copper, and aluminum, or a combination of these. These have excellent physical properties as base materials for brazing materials, and since there is accumulated knowledge about them, they are easy to handle.
  • the composition may include chromium, silicon, phosphorus, and boron in addition to nickel.
  • the molded body in the brazing material obtained by molding the metal powder of the present invention, the molded body may be any one or a combination of a molded body by extrusion molding, a molded body by vacuum extrusion, and a molded body by compression molding.
  • a molding method in which the metal powder is placed in a mold and dried is also possible.
  • the shape of the molded product is not limited, but it can be molded into, for example, a rod shape, or a ring or sheet shape.
  • the brazing method in the manufacture of a fin-tube heat exchanger using the brazing material formed from the metal powder of the present invention is as follows.
  • the fin tube type heat exchanger is assumed to include a fin multi-layer structure in which a number of fins are stacked and arranged at a predetermined interval, and a tube inserted into a through hole formed in the fin multi-layer structure so as to extend through the entire structure, and further assumed to be configured such that the brazing point is the contact point between the inner peripheral edge of the through hole in the fin multi-layer structure and the outer peripheral edge of the tube.
  • a groove is provided by cutting out a portion of the through hole toward the outer periphery, and a brazing material formed from metal powder molded into a rod shape as described in claim 5 is inserted through the groove, and a predetermined heat is input to the brazing material to perform brazing processing.
  • the brazing material of the present invention used in the brazing processing has a high heat input efficiency, improving the problem of low heat input efficiency that was an issue with conventional processing methods.
  • the brazing material and the brazing point are adjacent to each other, the problems of brazing material loss and deterioration of aesthetics that were an issue with conventional processing methods are also improved.
  • the problem of the brazing material blocking the heat dissipation space of the fins, resulting in a deterioration in heat dissipation efficiency, that was an issue with conventional processing methods is also improved.
  • the problem of uneven molten state of the brazing material which was a problem with conventional bar-shaped brazing materials made of metal blocks, is improved by the brazing process method of the present invention because the brazing process time can be shortened. Even if it is assumed that a time difference occurs between the molten state of the peripheral part and the center part when the brazing material of the present invention is used, the brazing material of the present invention can instantly change to the granular state of metal powder, so that the metal powder can be melted well in a short time even by radiant heat from the surroundings, and uniform and good wetting of the brazing process occurs.
  • FIG. 2 is a diagram simply showing an example of the composition of a brazing material formed from metal powder according to Example 1 of the present invention.
  • FIG. 13 is a diagram showing a brazing material produced by molding a metal powder through vacuum extrusion molding.
  • FIG. 2 shows a brazing material of a metal block made by another company having the same composition.
  • FIG. 13 is a diagram showing density as a function of the amount of added element.
  • FIG. 1 is a diagram showing the results of differential thermogravimetric analysis of a brazing material formed from metal powder according to the present invention and a brazing material in the form of a metal lump according to a conventional technique.
  • FIG. 13 is a diagram showing a brazing material produced by molding a metal powder through vacuum extrusion molding.
  • FIG. 2 shows a brazing material of a metal block made by another company having the same composition.
  • FIG. 13 is a diagram showing density as a function of the amount of added element.
  • FIG. 1 is a diagram showing the results of differential
  • FIG. 1 is a diagram simply illustrating the configuration of a fin-tube heat exchanger 100 that is brazed using a brazing material formed from a metal powder of the present invention.
  • FIG. 1 is a diagram showing a procedure for a brazing method between the fins 110 and the tubes 120 in the fin-tube heat exchanger 100 of the second embodiment (part 1).
  • FIG. 2 is a diagram showing a procedure for a brazing method between the fins 110 and the tubes 120 in the fin-tube heat exchanger 100 of the second embodiment (part 2).
  • FIG. 3 is a diagram showing the procedure of a brazing method between the fins 110 and the tubes 120 in the fin-tube heat exchanger 100 of the second embodiment (part 3).
  • FIG. 1 is a diagram simply illustrating the configuration of a fin-tube heat exchanger 100 that is brazed using a brazing material formed from a metal powder of the present invention.
  • FIG. 1 is a diagram showing a procedure for a brazing method between the fins 110 and the tubes 120 in the
  • FIG. 1 is a diagram simply illustrating the configuration of a fin-tube heat exchanger that is the subject of brazing treatment using a brazing material according to the prior art.
  • FIG. 1 is a diagram showing a case where a rod-shaped brazing material 30a made of a metal block is used in the prior art.
  • FIG. 1 is a diagram showing an example of a brazing process for a fin-tube heat exchanger according to the prior art.
  • FIG. 2 is a diagram simply illustrating an innovation in brazing processing for a fin-tube heat exchanger envisioned by the inventors.
  • 14 is a diagram showing a brazing process assumed in the new fin-tube heat exchanger proposed by the present inventors and having the configuration shown in FIG. 13.
  • FIG. FIG. 1 is a diagram showing the technique disclosed in Japanese Patent Laid-Open No. 55-92288 in the prior art.
  • FIG. 1 is a diagram simply showing an example of the composition of a brazing material formed from metal powder according to Example 1 of the present invention.
  • nickel alloys are used as the base material in all cases, but the composition of the brazing material formed from the metal powder of the present invention can be varied, and the composition shown in FIG. 1 is merely one example.
  • the compounding ratio after drying is 97.6% nickel brazing metal powder and 2.4% binder.
  • copper alloys there are various metals other than nickel alloys that can be considered, such as copper alloys. Although copper alloys are widely used in conventional technology, the present invention can also be applied to Cu-Mn-Ni copper alloys and Cu-Sn-Ti copper alloys, which are considered to be difficult to process. Additionally, powders of other metals, such as gold, silver, tin, aluminum, lead, phosphorus, chromium, tungsten, molybdenum, titanium, platinum, palladium, zinc, indium, molybdenum, manganese, and combinations thereof, can also be used.
  • other metals such as gold, silver, tin, aluminum, lead, phosphorus, chromium, tungsten, molybdenum, titanium, platinum, palladium, zinc, indium, molybdenum, manganese, and combinations thereof, can also be used.
  • the prototype is shown below.
  • the prototype was made using nickel brazing filler No. 1 in the list in FIG.
  • the nickel brazing material was made by powdering nickel using an atomizing method or the like to obtain a metallic powder of nickel brazing material. The powder was not melted, but was compressed into a rod shape by vacuum extrusion molding to obtain a molded body.
  • FIG. 2 is a diagram showing a brazing material produced by molding a metal powder experimentally produced by vacuum extrusion molding using the composition of List 1 shown in FIG.
  • Fig. 2(a) is a diagram showing the appearance of the brazing material formed from metal powder.
  • Figure 2(b) shows a photomicrograph of a cross section of a prototype braze material formed from the metal powder shown in Figure 2(a) at 30x magnification.
  • Fig. 2(c) is an enlarged microscope photograph at a magnification of 300 times higher than that of Fig. 2(b).
  • FIG. 2(c) it can be seen that even when formed into a rod shape by vacuum extrusion, the nickel alloy is not melted and remains in a granular state as a metal powder.
  • FIG. 3 shows a brazing material made of a metal block from another manufacturer having the same composition.
  • Fig. 3(a) shows the appearance of a metal block brazing material made by another company that has the same composition. Only one piece is shown.
  • Fig. 3(b) shows a micrograph of a cross section of a metal block brazing material made by another company, which has the same composition as Fig. 3(a).
  • the cross section is a vertical section.
  • the magnification is 30 times.
  • Fig. 3(c) is an enlarged microscope photograph at a magnification of 300 times higher than that of Fig. 3(b).
  • the brazing material of the metal block is a molten nickel alloy that has been formed into a block.
  • the metal block is a uniform, homogeneous block.
  • the state of the brazing material formed from the metal powder of the present invention shown in FIGS. 2(b) and 2(c) is clearly different from the state of the brazing material in the form of a metal block shown in FIGS. 3(b) and 3(c), and the powdery, granular metal powder can be clearly observed. It can be seen that the brazing material formed from the metal powder of the present invention has never been melted, but is in a powdery, granular state that has been physically compressed into a compact.
  • the grain size range of the metal powder in the brazing material molded from the prototype metal powder was 90% or more with a median diameter of 20 to 75 ⁇ m. Specifically, this is within the range shown in [Table 1] below, and it can be said that the overall grain size is substantially 63 ⁇ m or less.
  • the packing ratio of the brazing material formed from the metal powder was measured.
  • the packing ratio represents the ratio of the apparent density to the true density.
  • a brazing material made by another company with the same composition is also shown.
  • the filling rate of the prototype was as shown in Table 2 below.
  • the packing ratio was calculated by the ratio of the actually measured density to the theoretical value using the calculated density values of each metal shown in FIG.
  • the fill rate of the brazing material of the metal block of the other company is in the range of about 82% or 90%, but it is considered that such a low value range is calculated because flux and binder are also mixed in. If only the metal block part of the brazing material of the other company's metal block is measured, the fill rate is assumed to be 95% or more.
  • the packing ratio of the brazing material molded from the metal powder of the present invention is clearly smaller than that of the brazing material made from metal blocks by other companies, at about 60%.
  • This packing ratio can be adjusted by the pressure applied during extrusion molding.
  • the range of the filling rate of the metal powder in the compact is preferably 50% to 80%. If it is less than 50%, the binder is in a small amount, so the hardness is low and the brazing material formed from rod-shaped metal powder is easily broken when handled during brazing. If it is more than 80%, depending on the binder content, it becomes closer to a conventional metal block product and there is a risk of reduced heat input efficiency. Therefore, here, the range of the filling rate of the metal powder in the compact is assumed to be 50% to 80%.
  • a differential thermogravimetry analyzer is a device that can measure "thermogravimetry (TG),” which continuously measures the weight change while heating a sample at a constant rate, and "differential thermal analysis (DTA),” which measures the change in temperature difference between a reference material and a sample when it is heated together with the reference material.
  • TG thermogravimetry
  • DTA differential thermal analysis
  • a brazing material formed from the metal powder of the present invention and a brazing material in the form of a metal block according to the prior art were prepared as samples, and differential thermogravimetric analysis was carried out under the following measurement conditions.
  • Measurement equipment "Differential thermogravimetric analyzer (NEXTA STA-300: manufactured by Hitachi High-Tech Science Corporation)" Temperature conditions: room temperature to 1200°C Temperature rise condition: 10° C./min Sample amount: 10 ⁇ 1 mg
  • FIG. 5 is a diagram showing the results of differential thermogravimetric analysis (time changes of DTA (uV) and TG (wt%)) of the brazing material formed from metal powder according to the present invention and the brazing material in the form of a metal lump according to the prior art.
  • FIG. 5(a) is a graph showing the time change in DTA (uV) and TG (wt%) of a brazing material formed from the metal powder of the present invention
  • FIG. 5(b) is an enlarged view showing the change in the vicinity of where the powder melts in FIG. 5(a).
  • FIG. 5(c) shows the time-dependent changes in DTA (uV) and TG (wt%) of a brazing material for a metal block according to the prior art
  • FIG. 5(d) shows an enlarged view of the changes in the vicinity of where the metal block melts in FIG. 5(c).
  • the brazing material formed from the metal powder of the present invention started to melt after 97.4 minutes, and the sample was completely melted after 99.7 minutes. In other words, it took 2.3 minutes for the brazing material formed from the metal powder to start to melt and reach a state where it could be brazed.
  • the brazing material of the metal block manufactured by Company A started to melt after 97.4 minutes, and the sample was completely melted after 102.2 minutes. In other words, it took 5.2 minutes for the brazing material of the metal block to start to melt and become in a state suitable for brazing.
  • the brazing material made from the metal powder of the present invention has a large total area of the outer surface of the granular metal powder, resulting in a large heat input area, while the brazing material made from the metal block produced by Company A only has a heat input area from the ends of the rod-shaped outer surface, and only metal thermal conduction exists toward the center.
  • the brazing material of the present invention which is a compact formed by molding the metal powder into a predetermined shape, has an extremely high heat input efficiency.
  • FIG. 6 is a diagram simply illustrating the configuration of a fin-tube heat exchanger 100 to which brazing treatment is to be performed using the brazing material formed from the metal powder of the present invention.
  • Fig. 6(a) is a perspective view of the fin 110 viewed from a slight angle with the surface of the fin 110 through which the tube 120 is inserted facing the front
  • Fig. 6(b) is a longitudinal cross-sectional view taken along the longitudinal center line of the fin 110 with the surface of the fin 110 through which the tube 120 is inserted facing the front.
  • the cross-sectional view is taken vertically through the center of the tube 120 and a groove 112 (described later). Note that the longitudinal cross-section in Fig. 6(b) is shown hatched.
  • the fins 110 which are heat sinks, are fabricated by pressing a thin plate of copper, SUS, aluminum, or the like to form tube through-holes 111 and then cutting the plate to a predetermined size.
  • the tube through-holes 111 are provided to match the outer shape of the tubes 120. They may be circular or flat. In this example, they are circular.
  • the material of the fins may be any of those used in the prior art. For example, copper, SUS, and aluminum alloy materials are often selected from the viewpoints of moldability, heat transfer, and light weight.
  • the brazing method for manufacturing the fin-tube heat exchanger of the present invention may be applied to any of the materials.
  • the fins 110 in the finned tube heat exchanger 100 are configured to be multi-layered. There is no limit to the number of fins 110, and it may be, for example, several hundred. In this example, 36 fins are stacked. There is also no limit to the spacing between the fins 110, and they may be stacked with a gap of, for example, several millimeters. When the multi-layered fins 110 are stacked, all of the tube through holes 111 drilled in the fins 110 are aligned in the same position, forming a continuous hole space. In addition, the number of tube through holes 111 may be one or more.
  • a configuration is also possible in which multiple tubes 120 are inserted, and a U-shaped curved portion is provided at the end of the tube to fold the circulation path and make the fins go back and forth multiple times.
  • a U-shaped curved portion is provided at the end of the tube to fold the circulation path and make the fins go back and forth multiple times.
  • the fin 110 according to the second embodiment has a groove 112 on the upper outer side of the tube insertion hole 111.
  • This groove 112 is for providing a space for inserting and storing the brazing material 200 formed from the metal powder of the present invention in a continuous manner at a position adjacent to the tube 120, as will be described later.
  • the groove 112 is provided on the upper outer side of the tube insertion hole 111, and is integrally connected to and adjacent to the tube insertion hole 111. Therefore, when the brazing material 200 formed from the metal powder of the present invention inserted into this groove 112 melts, it immediately reaches the tube 120 directly below, which has the advantage of expanding the "wetting" area.
  • the tube 120 is a hollow tube and can be any metal tube with high thermal conductivity. There are no particular restrictions on the material, but copper or copper alloy tubes are often used due to their workability, heat transfer, ease of installation, and corrosion resistance.
  • the brazing process between the fins 110 and the tubes 120 in the fin-tube heat exchanger 100 according to the second embodiment is carried out in the following manner. 7 to 9, (a) is a perspective view seen from a slight angle with the surface of the fin 110 through which the tube 120 is inserted as the front, and (b) is a vertical cross-sectional view cut vertically along the center line with the surface of the fin 110 through which the tube 120 is inserted as the front, as in Fig. 6. The vertical cross-section in (b) is shown hatched.
  • a rod-shaped brazing material 200 formed from the metal powder of the present invention is inserted into the space formed by the groove 112 on the upper outer side of the tube insertion hole 111. It is preferable that the length of the brazing material 200 formed from the metal powder of the present invention is approximately the same as the penetration length of the multi-layered fin 110 .
  • a heat source of a predetermined temperature is brought into contact with the end of the brazing material 200 formed from the metal powder of the present invention, and heat is input.
  • a heat source of 200 degrees is used.
  • the brazing material 200 formed from the metal powder of the present invention has a high heat input efficiency as shown in Example 1, and the brazing material melts efficiently in a short time, and the brazing material melts not only at the ends but also at the center in a short time. As a result, as shown in FIG.
  • the brazing material 200 formed from the metal powder of the present invention quickly melts in its entirety, and the brazing material 200 that melts and becomes liquid in the space of the groove 112 reaches the tube insertion hole 111 directly below in an extremely short time and spreads to the outer circumferential edge of the tube 120 that is in contact with the inner circumferential edge of the tube insertion hole 111.
  • the so-called “wetting” spreads in a short time to the contact point between the fin 110 and the tube 120, that is, the brazing point, and good “wetting" is achieved throughout the entire brazing point.
  • FIG. 9 is a diagram showing the completed state of the brazing process between the fins 110 and the tubes 120 in the fin-tube heat exchanger 100.
  • the brazing material 200 formed from the metal powder of the present invention has a small amount of binder and requires a short drying process, so it takes only a short time to go from the state shown in Fig. 7 to the state shown in Fig. 9.
  • the nickel alloy brazing material easily solidifies into a metallic state when it is cooled to 140°C or lower, so it can quickly cool down from the heat input temperature of 200°C to the state shown in Fig. 7.
  • strong metal bonding is made between the fins 110 made of aluminum metal material and the tubes 120 made of copper metal material using a brazing material made of nickel alloy metal material, resulting in an extremely strong fin-tube heat exchanger 100.
  • the brazing material of the present invention which is made by molding metal powder into a rod shape, can be used as a wide variety of brazing materials.
  • the brazing method for manufacturing a fin tube heat exchanger using the brazing material formed from the metal powder molded into a rod shape according to the present invention can be applied to the brazing process in manufacturing a wide variety of fin tube heat exchangers, and can be applied to a method for brazing two metal members or ceramic members in various mechanical devices, not limited to fin tube heat exchangers.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Powder Metallurgy (AREA)
  • Details Of Heat-Exchange And Heat-Transfer (AREA)

Abstract

La présente invention aborde le problème consistant à fournir : un nouveau matériau de brasage qui est un corps moulé ; et un procédé d'amélioration d'un traitement de brasage pour un échangeur thermique de type à tubes à ailettes utilisant le matériau de brasage. Une poudre métallique préparée par pulvérisation d'un métal qui sert de matériau de brasage, tel qu'un alliage de nickel, est comprimée pour obtenir une forme souhaitée sans qu'il soit nécessaire de faire fondre la poudre métallique, ce qui permet de produire un corps moulé. 90 % ou plus de la poudre métallique est composée d'une poudre présentant un diamètre de particule médian de 20 à 75 µm, et le taux de remplissage de la poudre métallique dans le corps moulé varie de 50 à 80 %. Un échangeur thermique de type à tubes à ailettes 100 est conçu de façon à posséder une rainure 112 formée en entaillant une partie d'un trou de pénétration de tube 111 dans une ailette 110 jusqu'au côté périphérique externe. Un matériau de brasage 200 de la présente invention, qui est produit par moulage d'une poudre métallique sous la forme d'une barre, est inséré et introduit à travers la rainure 112, puis chauffé en vue de la mise en œuvre d'un brasage.
PCT/JP2023/028420 2022-10-17 2023-08-03 Matériau de brasage produit par moulage d'une poudre métallique, et procédé de traitement de brasage dans la production d'un échangeur thermique de type à tubes à ailettes l'utilisant Ceased WO2024084777A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP2024566803A JP7726569B2 (ja) 2022-10-17 2024-07-29 金属粉体を成形したろう付材およびそれを用いたフィンチューブ式熱交換器の製造におけるろう付処理方法
PCT/JP2024/026963 WO2025028483A1 (fr) 2022-10-17 2024-07-29 Élément de brasage produit par moulage de poudre métallique et procédé de brasage dans la fabrication d'un échangeur de chaleur de type tube à ailettes l'utilisant

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JP2022166042A JP2025179273A (ja) 2022-10-17 金属粉体を成形したろう付け材およびそれを用いたフィンチューブ式熱交換器の製造におけるろう付け処理方法
JP2022-166042 2022-10-17

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PCT/JP2024/026963 Pending WO2025028483A1 (fr) 2022-10-17 2024-07-29 Élément de brasage produit par moulage de poudre métallique et procédé de brasage dans la fabrication d'un échangeur de chaleur de type tube à ailettes l'utilisant

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02247454A (ja) * 1989-03-20 1990-10-03 Uchida Seisakusho:Kk １缶２回路式給湯機の熱交換器
JPH04108957U (ja) * 1991-02-25 1992-09-21 株式会社鈴木鉄工所 伝熱管とフインとのロウ付け構造
JPH07308794A (ja) * 1994-05-19 1995-11-28 Showa Alum Corp 低温ろう付用ろう材
JPH11170089A (ja) * 1997-11-12 1999-06-29 Kin Meichin ろう材圧粉成形体、ろう材仮焼体及びそれらの製造方法
JP2016540644A (ja) * 2013-11-22 2016-12-28 ホガナス アクチボラグ （パブル） 鑞付け用プリフォーム
JP2020503174A (ja) * 2016-12-16 2020-01-30 スウェップ インターナショナル アクティエボラーグ ろう付け用材料

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4483880B2 (ja) * 2007-03-15 2010-06-16 セイコーエプソン株式会社 成形体形成用組成物、脱脂体および焼結体

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02247454A (ja) * 1989-03-20 1990-10-03 Uchida Seisakusho:Kk １缶２回路式給湯機の熱交換器
JPH04108957U (ja) * 1991-02-25 1992-09-21 株式会社鈴木鉄工所 伝熱管とフインとのロウ付け構造
JPH07308794A (ja) * 1994-05-19 1995-11-28 Showa Alum Corp 低温ろう付用ろう材
JPH11170089A (ja) * 1997-11-12 1999-06-29 Kin Meichin ろう材圧粉成形体、ろう材仮焼体及びそれらの製造方法
JP2016540644A (ja) * 2013-11-22 2016-12-28 ホガナス アクチボラグ （パブル） 鑞付け用プリフォーム
JP2020503174A (ja) * 2016-12-16 2020-01-30 スウェップ インターナショナル アクティエボラーグ ろう付け用材料

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