JPH03204130A - Manufacture of flat tube for heat exchanger - Google Patents

Abstract

PURPOSE:To obtain a flat tube for a heat exchanger with excellent productivity by forming continuously supplied stock into a flat tube and inserting a worked insert continuously into it and brazing them. CONSTITUTION:A tube stock 1 is formed by flat tube forming rolls 3-8 in sequence into a flat tube and an insert 19 is inserted on the way. The insert 19 is obtained by supplying a steel strip 11 continuously from an uncoiler 12, curving it by guides 13, 14 in the wavy form and working it by insert wave forming rolls 15-18 into the insert shape. It is sprayed by a flux spray gun 20 with flux, dryed by a drying device 21 and inserted continuously. After the insert is inserted into the tube when it is flattened, the upper part of the flattened tube is formed by rolls 9, 10 and an edge part is heated and welded through a high-frequency induction coil 22 and welded with pressure by squeeze rolls 23, 24. The burrs 25 generated are removed with a bite 26, and the tube- intesor roll and insert are soldered in a soldering furnace, cooled by a cooles 27 straightened with a longitudinal correcting roll group 34-39, lateral correcting group rolls 40-45, cut with a cutter 46 to obtain a flattered tube 47.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing flat tubes used in aluminum heat exchangers such as automobile radiators and condensers.

[Conventional technology and its issues]

Hitherto, as this type of flat tube, for example, an extruded tube as shown in FIG. 5, and those disclosed in Japanese Patent Application Laid-Open No. 62-207572 and Japanese Patent Application Laid-open No. 63-242432 are known.

The flat tube disclosed in Japanese Patent Application Laid-Open No. 62-207572 is formed using a conventional tube mill using a material clad with a brazing filler metal on the outside or both sides, cut to a specific length, and then degreased. Inserts are formed by roll processing, goo forming, or uniform extrusion molding of materials that are not clad with brazing filler metal or that are clad on both sides, and are degreased, sprayed with flux, dried, and cut to a predetermined length. The insert is inserted into the tube, assembled, rolled and brought into close contact, and then the heat exchanger is brazed using the conventional method, in which the crest of the insert wave is brazed to the inner wall of the flat tube. In this way, the flat tube shown in FIG. 6 is obtained.

JP-A-63-242432 will be explained based on FIG. 7. In this figure, (86) has a substantially θ-shaped cross section and is melted inside the substantially central portion of both wall surfaces (88) and (89). First, Al (91
), (91) are joined, and their tips (92) are brought into contact with the opposing wall surface (89), and in this state they are fixed with a jig or core assembled, and then heated by a conventional method. However, the conventional method for manufacturing flat tubes has various problems as described below.

■It is difficult to make ultra-thin walled tubes.

■It is difficult to make tubes with brazing filler metal cladding on one side or screen.

■Manufacturing costs are relatively high.

Further, when obtaining a flat tube using the manufacturing method disclosed in Japanese Patent Application Laid-Open No. 62-207572, there are the following problems.

■It is time-consuming and costly because it is necessary to insert inserts of specified dimensions one by one into flat tubes of specified dimensions off-line.

■Flat tubes and insert materials are made of thin-walled materials, so they tend to buckle or bend during handling. In addition, dimensional accuracy tends to deteriorate.

(2) On the other hand, when obtaining a flat tube using the manufacturing method disclosed in JP-A-63-242432, there are the following problems.

■Since there are only two internal fluid flow paths, the heat exchange rate is relatively poor.

■In the case of wide flat tubes, there is only one support, so the tube is easily deformed by internal and external pressure.

■In the case of a wide flat tube, there is only one thing to support it, so
Strength is relatively low. In addition, bending and twisting are likely to occur.

[Problem to be solved by the invention]

The present invention was made to solve these conventional problems, and its purpose is to assemble flat tubes and inserts while continuously supplying and welding them, thereby achieving high strength, good precision, and low manufacturing costs. It is an object of the present invention to provide a method for manufacturing aluminum alloy flat tubes for heat exchangers with relatively low productivity with good productivity.

[Means and effects for solving the problem] The present invention continuously supplies an aluminum alloy strip, forms it into a flat tube shape, bends an insert into a corrugated or rectangular shape, and inserts a continuous sheet into the inside of the flat tube. The invention of claim 1 provides a method for manufacturing a flat tube for a heat exchanger, characterized in that the flat tube is inserted, integrally formed, and the edges of the flat tube are welded, and the aluminum alloy strip is continuously supplied. It is characterized by forming it into a flat tube shape, bending the insert into a corrugated or rectangular shape, continuously inserting it into the flat tube, molding it integrally, welding the edges of the flat tube, and then reducing the diameter. The invention of claim 2 provides a method for manufacturing a flat tube for a heat exchanger, in which an aluminum alloy strip is continuously supplied and formed into a flat tube shape, and an insert is bent into a corrugated or rectangular shape,
Claims a method of manufacturing a flat tube for a heat exchanger, characterized in that the flat tube is continuously inserted into the flat tube and integrally formed, the edges of the flat tube are welded, and then the inner surface of the flat tube and the insert are brazed. This is invention No. 3.

That is, in the present invention of claim 1, for example, as shown in FIG. Rolls (3) to (8) are used to sequentially form the aluminum into a flat tube shape.
12) and guides (13) and (14).
It is bent into a wavy or rectangular shape, processed into an insert shape using insert wave forming rolls (15) to (18), and is sprayed with flux using the flux spray coating device (20), and then coated with a drying device (21). Insert continuously while drying quickly and quickly. After inserting the insert into the tube that is in the middle of being flattened, the upper part of the flattened tube is formed with rolls (9) and (10), and the edge is shaped like the welded part (51) in Figure 3 through the high-frequency induction coil (22) for welding. are welded by high-frequency induction heating and pressed together with squeeze rolls (23) and (24). The generated outside welding paris (25) are removed with a cutting tool (26), and then passed through a cooling device (27) and cooled with a shower of cooling water, and then vertical straightening rolls (34) to (3)
9), straightened with horizontal straightening rolls (40) to (45), cut with a cutter (46) synchronized with the line speed, and made into a flat tube (47).
).

Further, the invention of claim 2 provides a cooling device (
27), and after being cooled by showering cooling water, the diameter of the flat tube is reduced by a group of tube shrinking sizing rolls (28) to (33), and the flat tube and insert are brought into close contact with each other, and the shape is formed. This is an additional process. By adding this diameter reduction step, a flat tube with even higher dimensional accuracy than the case of claim 1 can be obtained.

Next, the invention of claim 3 is similar to that shown in FIG.
After removing step 26), a step of brazing the inner surface of the flat tube and the insert in a brazing furnace (not shown) is added. By this brazing process, the inner surface of the flat tube and the insert are brazed, so that there is no misalignment of the insert in the subsequent process (high precision can be obtained).

However, in the present invention, the diameter reduction process using the tube shrinking sizing roll group (28) to (33) may be performed after the cooling device as shown in FIG. It may be applied later, or it may be applied both (
(not shown).

The flat tube obtained as described above is shown in FIG. (4
8) is the outer brazing material of the flat tube, (49) is the core material, (50)
is the inner brazing material, and (51) is the welding part. Although the inner wall of the flat tube and the corrugated top (52) of the insert (19) have not yet been soldered, this flat tube has no bends or twists, has excellent strength, and is easy to handle during handling. There is no bending or other damage.

Next, a method for manufacturing a heat exchanger using the flat tube obtained as described above will be explained. For example, as shown in Fig. 4, insert the flat tube (47) containing the insert into the headers (54) and (55), and insert a corrugated tube between the flat tube (47) and the reinforcing plates (56) and (57). Attach the bent corrugated fin (53) to the union (60), (
61), (62) and pipes (63) to assemble an aluminum heat exchanger core.

After this, potassium aluminum fluoride flux (KAI2F, K2A I) with non-hygroscopic and non-corrosive properties
F s, K3A E Fa, etc. singly or as a mixture), and after drying, apply in a vacuum brazing oven or N2
A heat exchanger is produced by heating and brazing in a gas atmosphere brazing furnace and cooling.

Such a heat exchanger has good thermal efficiency, no problems such as leakage, the inner wall of the flat tube and the top of the corrugated fins of the insert are well soldered, and each flow path is independent. A good product that maintains its condition can be obtained.

Therefore, in the present invention, as the material of the aluminum alloy clad strip plate (1) for flat tubes, which is the material of the flat tube, for example, 3003, Al2Mn-Cu alloy, Affi-Mg-31-Cu, etc. are used as the core material. As the brazing material, an Al2-3l alloy such as 4045.4004 can be used, and a material in which one or both sides of a core material is clad with a brazing material can be used. Further, for example, the outer and inner portions of the flat tube have a brazing material. When contacting the fin reinforcing plate or insert and brazing with the mating brazing material, it is possible to use one without any brazing material cladding or one with brazing material on one side. The coverage of the brazing filler metal is preferably about 5 to 30% of the thickness of the core material.

In addition, the material for the insert (19) is 3 as the core material.
003, etc., and 4045.4004 as the brazing material.
A material with brazing metal clad on both sides can be used, but in this case as well, if there is brazing metal on the inside of the flat tube and it is possible to solder with the other brazing metal, no brazing metal is clad. You may also use bare wood that is not available.

Although flux is used when a brazing filler metal is used, it is not necessary to apply flux when soldering is performed by vacuum brazing in the heat exchanger assembly process. Good results can be obtained by using a flux that is non-hygroscopic and non-corrosive.

Therefore, the present invention provides that the above-mentioned flat tube and insert may be brazed during the manufacturing of the flat tube, or may be brazed during the subsequent process of brazing the heat exchanger; in the former case, soldering may be performed. In the latter case, one step can be omitted. Furthermore, both can be carried out in combination, in which case the layer strength and adhesion are improved.

As described above, the present invention is capable of forming heat exchangers by continuously inserting processed inserts during the process of forming continuously supplied materials into flat tubes, and soldering the flat tubes or the flat tubes and the inserts. Compared to the conventional off-line method of manufacturing flat tubes by inserting an insert of a specific length into a flat tube of a specific length, manufacturing can be done with much higher productivity. In addition, since the insert is inserted and the diameter is reduced, the inner wall of the flat tube and the top of the corrugated or rectangular shape of the insert are in close contact with each other, and a perfect connection can be achieved during the brazing process.

Furthermore, with conventional non-corrosion flux brazing, a sound joint cannot be obtained unless flux is applied to the inside of the tube and/or the insert before soldering.
Flux treatment is complicated, but in the present invention, non-corrosion flux (for example, K
2Aj for Aj2F4+! Fs) Since the coating process is performed online, productivity is better than conventional offline processing.

When the flat tubes described above are incorporated into a heat exchanger, a heat exchanger with good solderability and excellent strength can be manufactured economically. Note that the present invention is not limited to aluminum, but also copper,
It can also be applied to the manufacture of flat tubes made of other metals.

〔Example〕

An embodiment of the present invention will be described below.

Example 1 In this example, an example in which the edges of a flat tube are welded and the inner wall of the tube and an insert are brazed will be described with reference to FIG.

(1) is an aluminum alloy clad strip plate for flat tubes, which is a raw material for flat tubes, and is continuously supplied from an uncoiler (2). In the example, the blank plate of the flat tube is made of 3003 alloy as the core material and has a thickness of 0.3 with 10% coating of 4045 alloy on both sides.
Using an aluminum alloy clad material with tan and diameter of 31 m, it was fed at a speed of 100 m/+win, and was sequentially formed into a flat tube shape by flat tube forming rolls (3) to (8).
Insert the aluminum alloy insert (19) in the middle. The aluminum alloy insert (19) is
The aluminum alloy strip plate (11) for insert material is continuously supplied from the uncoiler (12), and then the guide (13)
) and (14) to form a wave shape, and the insert wave forming rolls (15) to (18) process the insert into the shape of the insert.Flux is sprayed and applied using the flux spray coating device (20), and then the drying device ( 21) while rapidly drying. In the example, the insert material was made of 3003 alloy with a thickness of 0.15 mm and a width of 19 mm.
100 using 5mo+ bare material and synchronized with the pipe production speed.
It was inserted at a speed of m/a+in. The flux is approximately 5g/potassium aluminum fluoride salt Franks (KAj2F-+KtAIIFs), which has non-hygroscopic and non-corrosive properties.
It was applied with IF spray and dried with hot air. After inserting the insert into the tube in the middle of flattening, the upper part of the flattened tube is formed with rolls (9) and (10), and then a high-frequency induction coil (2) for welding is used.
High frequency induction heating welding is performed on the edges through (23),
(24) was pressed with a squeeze roll.

The generated outside welding pad (25) is removed with a hide (26), the inner wall of the pipe and the insert are soldered together through a brazing furnace (not shown), and then the tube is passed through a cooling device (27) and cooled by showering with cooling water. Then, the navy blue straightening roll group (3
4) to (39), the tubes were straightened by horizontal straightening roll groups (40) to (45), and cut by a cutting device (46) synchronized with the line speed to obtain flat tubes (47).

FIG. 3 shows the shape of the flat tube (47) obtained in the above process. (48) is the outer brazing material of the flat tube, (49) is the core material, (50) is the inner brazing material, and (51) is the welding part. The obtained flat tube had no bends or twists, and had excellent strength and did not bend during handling.

Example 2 In this example, an example in which the inner wall of the flat tube and the insert were brazed during the heat exchanger assembly process will be described with reference to FIG. 2. (
1) is an aluminum alloy clad strip plate for flat tubes, which is a raw material for flat tubes, and is continuously supplied from an uncoiler (2). In the example, the blank plate of the flat tube is made of 3003 alloy as the core material, and both sides are coated with 10% of 4045 alloy, and the plate thickness is 0.3.
Using aluminum alloy clad material with a width of 31 mm and a width of 31 mm,
The tube is supplied at a rate of 100 m/min and is sequentially formed into a flat tube shape by flat tube forming rolls (3) to (8), and an aluminum alloy insert (19) is inserted in the middle. The aluminum alloy insert (19) is (11)
An uncoiler (
12) and guides (13) and (14).
Bend it into a wave shape with the insert wave forming roll (15) ~ (
At the same time as processing into the shape of the insert at step 18), at step (20)
Flux is sprayed and applied using a flux spray coating device, and is continuously inserted while being rapidly dried by a drying device (21).

In the example, the insert material is made of 3003 alloy with a thickness of 0.
A bare material with a diameter of 15 mm and a width of 19.5 mm was used and inserted at a speed of 100 m/win, which was synchronized with the pipe making speed. The flux is potassium aluminum fluoride salt Franks (KAfF, +K), which has non-hygroscopic and non-corrosive properties.

AzFs) was spray applied at a rate of about 5 g/rff and dried with hot air. After inserting the insert into the tube that is in the middle of flattening, roll it (9
) and (10), the upper part of the flat tube was formed, and then the edges were welded by high-frequency induction heating through a high-frequency induction coil (22) for welding, and pressed together with squeeze rolls (23) and (24). Hide (26) the generated outside welding paris (25)
After that, it is passed through the cooling device (27), cooled by showering with cooling water, and the tube shrinking roll group (27) is cooled.
The tube was shrunk in steps 8) to (33), the flat tube and the insert were brought into close contact, and the tube was shaped.

After that, it is straightened by the straightening roll group (34) to (39) and the horizontal straightening roll group (40) to (45), cut by the cutting device (46) synchronized with the line speed, and the flat tube (47) is cut. I got it.

FIG. 3 shows the shape of the flat tube (47) obtained in the above process. (48) is the outer brazing material of the flat tube, (49) is the core material, (50) is the inner brazing material, and (51) is the welding part. Although the inner wall of the flat tube and the top (52) of the insert (19) are not yet soldered together, there is no bending or twisting, and the tube has excellent strength, making it easy to handle. It didn't bend.

Using this flat tube, a heat exchanger was actually assembled by brazing. That is, using a pair of fins made of 3003 alloy with a thickness of 0.15 mm and a width of 16 mm, insert the flat tube (47) containing the insert (19) into the header (5) as shown in Figure 4.
4) Insert the corrugated fins (53) into the tube (47) and the reinforcing plates (56) and (57) between the tube (47) and the reinforcing plates (56) and (57), and attach the union (60),
An aluminum heat exchanger core was assembled by attaching (61), (62) and pipes (63). In this way, approximately 5 g/post-spray of aluminum potassium fluoride salt Franks (KA/2F, +KzAj!Fi), which has non-hygroscopic and non-corrosive properties, is applied, dried at 100-150°C, and then exposed to a N2 gas atmosphere ( Using a brazing furnace (1 atm),
Raise the temperature to 610°C at a rate of 30 to 50° (:/min)
Brazing was performed by holding for 20 minutes, and cooling was performed to produce an aluminum heat exchanger. These aluminum heat exchangers had good thermal efficiency and no problems such as leakage occurred. In addition, when we took out the flat tubes from these heat exchangers and observed the connection between the inner wall of the flat tube and the top of the corrugated fins, we found that they were very well brazed and that each flow path was independent. It was in good condition not only to prevent cross-flow inside the tube, but also to prevent rupture of the tube at normal operating pressures and maintain the structural integrity of the assembly.

Example 3 In this example, an example in which no flux is applied will be explained based on FIG. 2. (1) is an aluminum alloy clad strip plate for flat tubes and is continuously supplied from an uncoiler (2).

In the example, the blank plate of the flat tube is an aluminum alloy clad material with a thickness of 0.3 mm and a width of 31 mm, with a core material of 3003 alloy and 10% coating of 4004 alloy on both sides.
It is supplied at a speed of m/1 inch and is sequentially formed into a flat tube shape by flat tube forming rolls (3) to (8), and an aluminum alloy insert (19) is inserted in the middle. The aluminum alloy insert (19) is (11)
An uncoiler (
12) and guides (13) and (14).
Bend it into a wave shape with the insert wave forming roll (15) ~ (
Process it into the shape of the insert in step 18). In this embodiment, the inserts (19) are inserted continuously without applying flux. In the example, the insert material is a bare material of 3003 alloy with a plate thickness of 0.15 mm and a radius of 19.5 mm.
The tube was inserted at a speed of Loom/min synchronized with the pipe forming speed. After inserting the insert (19), roll (9), (1
The upper part of the flat tube was formed in step 0), and then the edges were welded by high-frequency induction heating through a high-frequency induction coil for welding (22), and pressed together with squeeze rolls in steps (23) and (24).

Remove the generated outside welding burr (25) with pi) (26), then put it in a cooling bag! (27), cooled by showering cooling water,
- (33) The tube was shrunk, the flat tube and the insert were brought into close contact, and the tube was shaped. After that, vertical straightening roll groups (34) to (39), horizontal straightening roll groups (40) to (4)
The tube was adjusted in Step 5) and cut using the cutting device in Step 46 synchronized with the line speed to obtain the flat tube in Step 47.

The third part shows the shape of the flat tube (47) obtained in the above process. (4B) is the outer brazing material of the flat tube, (49) is the core material, (50) is the inner brazing material, and (51) is the This is the welding part.

The flat tube still has the inner wall of the flat tube and the insert) (19
Although the top part (52) of the insert in ) was not soldered, it did not bend or twist, and it also had excellent strength and did not bend during handling.

Next, a heat exchanger was actually assembled using brazing using this flat tube. That is, the plate thickness of 3003 alloy is 0.15 m.
m, using a pair of fins with a width of 16 mm, insert the flat tube (47) containing the insert (19) into the headers (54) and (55) as shown in Figure 4, and insert the flat tube (47),
A corrugated fin (53) bent into a corrugated shape is attached between the reinforcing plates (56) and (57), and the union (60
), (61), (62) and pipe (63),
An aluminum heat exchanger core was assembled. Place the assembled core in a vacuum furnace and heat it at a vacuum level of 5 Xl0-'Torr.
Blazing was performed by holding at 10° C. for 3 minutes, and cooling was performed to produce an aluminum heat exchanger. These aluminum heat exchangers had good thermal efficiency and no leakage problems were ordered. In addition, when we took out the flat tubes from these heat exchangers and observed the connection between the inner wall of the flat tube and the top of the corrugated fins, we found that they were very well brazed and that each flow path was independent. This condition was good for not only preventing cross-flow inside the tubes, but also for preventing tube rupture at normal operating pressures and maintaining the structural integrity of the assembly.

In the above example, high frequency induction welding was used as the welding method for the flat tube, but high frequency contact welding, AC-T I
Various welding methods such as C, welding, DC5P-TAG welding, and laser welding can be used.

〔Effect of the invention〕

As described above, according to the method of the present invention, the inner wall of the flat tube has an extremely thin wall and a cladding layer of brazing material, and is strong enough to not bend or bend during handling. The waveform of the insert or the top of the rectangle is soldered,
This method has remarkable industrial effects, such as being able to manufacture highly productive aluminum flat tubes for heat exchangers in which independent flow channels are formed.

[Brief explanation of drawings]

FIGS. 1 and 2 are perspective views of equipment for manufacturing aluminum flat tubes for heat exchangers according to an embodiment of the present invention. FIG. 3 is a cross-sectional view of a flat tube manufactured according to an embodiment of the present invention, FIG. 4 is a perspective view of an aluminum heat exchanger manufactured using the flat tube of the present invention, and FIG. 5 is a conventional FIG. 6 is a cross-sectional view of an example of a multi-hole flat tube manufactured by extrusion, and FIG. 7 is a cross-sectional view of a tube manufactured by another conventional heat exchanger manufacturing method.
FIG. 3 is a cross-sectional view of a welded tube for a heat exchanger manufactured by another conventional forming method. 1... Aluminum alloy clad strip plate for flat tubes, 2.
・・Uncoiler-3～8・・Flat tube forming roll, 91
0... Roll, 11... Aluminum alloy strip plate for insert, 12... Uncoiler-13, 14...
- Guide, 15-18... Insert wave forming roll, 19... Insert, 20... Flux injection 11 cloth device, 21... Drying device, 22... High frequency induction coil, 23° 24...・Squeeze roll, 2
5...Harness outside welding, 26...Hide, 27...
- Cooling device, 28-33... tube shrinking sizing roll, 34-39... vertical straightening roll, 40-45... horizontal straightening roll, 46... cutting machine, 47... flat tube,
48...Outer brazing metal (clad metal), 49...
Heartwood, 50...Inner brazing material (cladding material), 51.
... Welding part, 52... Top of insert.

Claims (6)

[Claims] (1) Continuously supply an aluminum alloy strip, form it into a flat tube, bend the insert into a corrugated or rectangular shape, continuously insert it into the flat tube, form it integrally, and A method of manufacturing a flat tube for a heat exchanger, the method comprising welding the edges. (2) Continuously supplying an aluminum alloy strip, forming it into a flat tube shape, bending the insert into a corrugated or rectangular shape, continuously inserting it into the flat tube, forming it integrally, and forming it into a flat tube. A method for manufacturing a flat tube for a heat exchanger, characterized in that the edges are welded and then reduced in diameter. (3) Continuously supplying an aluminum alloy strip, forming it into a flat tube shape, bending the insert into a corrugated or rectangular shape, continuously inserting it into the flat tube, forming it integrally, and forming the edge of the flat tube. 1. A method for manufacturing a flat tube for a heat exchanger, which comprises welding the inner surface of the flat tube and an insert after welding the inner surface of the flat tube. (4) The aluminum alloy strip is clad with a brazing material on one or both sides, or is not clad at all.
3. The method for manufacturing a flat tube for a heat exchanger according to 2 or 3. (5) The method for manufacturing a flat tube for a heat exchanger according to claim 1, 2 or 3, wherein the insert is clad with brazing filler metal on both sides or is not clad at all. (6) The method for manufacturing a flat tube for a heat exchanger according to claim 1, 2 or 3, characterized in that inserts coated with flux or not coated with flux are continuously inserted into the flat tube.