JPH06137778A - Grooved rolling apparatus of bar for welding heat exchanger tube and weld flat heat exchanger tube - Google Patents

Abstract

PURPOSE:To achieve higher reliability in the quality of welding by performing a grooved rolling of a bar for a welding heat exchanger tube in such a manner that no variations are caused in the width and in the shape of the end rim of the bar to improve butting condition by a tubular forming. CONSTITUTION:A surface desired to work a bar of a groove forming roll 1 is made in a horizontal symmety to prevent twisting in working. A buffer area C1 is arranged with a gap part for absorbing the bar member extruded toward the center part of a groove forming part 1A while a buffer area C2 of the bar member is provided between a side rim rolling part 1B and a protruding thread 2' for grooving adjacent thereto. Moreover, a flange 9 is provided at an end part of a support roll 8 to restrain expanse across the width thereof so that the expanse across the width of the bar 11 is restrained as caused by the grooved rolling thereby allowing the absorption of a flow of the texture of the bar with the buffer areas C1 and C2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grooved rolling apparatus for welding heat transfer tubes used in a pre-welding process in manufacturing inner groove welded heat transfer tubes used for heat exchangers of air conditioners, and processing by this apparatus. Welding flat heat transfer tube using strip material.

[0002]

2. Description of the Related Art Household air conditioners are being made compact in order to make a living space comfortable. To achieve compactness, it is achieved by reducing the size of the components as a whole.

A large part of the air conditioner has a heat exchange part,
Copper having good thermal conductivity is used for the heat transfer tube through which the heat medium passes, and grooves are formed, for example, in a spiral shape on the inner surface in order to greatly improve efficiency.

The mainstream of the production of the heat transfer tube with inner groove is a method of producing a seamless copper tube by processing grooves from a billet material through extrusion-rolling-extraction.

Recently, in order to make a heat transfer tube with an inner groove thin,
As shown in FIG. 7, the raw strip 1 is processed by the grooved rolling part 21.
A method of forming a welded heat transfer tube 13 by applying a grooved rolling process to No. 0 to form a tubular shape by the tubular forming part 22 and welding the abutting part with an electric resistance welding device 23 has started to be used.

This high-frequency welding method can reduce the diameter of the copper pipe as compared with the seamless manufacturing method, and is therefore advantageous as a measure for downsizing the heat exchange section.

In addition, a car air conditioner is conventionally equipped with a heat exchange tube,
As shown in FIG. 8 (a), a harmonica pipe 25 formed by extrusion of aluminum or a flat pipe 27 of high frequency welded aluminum shown in FIG. The attached inner fin tubes 26 are alternately stacked via the outer fins 29 as shown in FIG.
It is used by ventilating 9 parts.

[0008]

Since a heat transfer tube produced by high frequency welding has a welded portion as compared with a seamless tube,
The reliability of this weld needs to be established.

The conditions necessary for welding must be satisfied in order to ensure reliable welding. For this purpose, it is necessary to eliminate the conditions that are necessary for welding but that may actually deviate from the proper values.

The main conditions of welding are (1) welding temperature ← heat input × speed × thickness × penetration angle × resistance, (2) butt ← parallel butt ×
Pressing margin ← Board width × thickness × preform × slit shape,
(3) Atmosphere ← non-oxidation ← Ar gas flow rate.

The heat input control is performed by using each variation factor, and the control methods of the welding temperature and the welding atmosphere in the above (1) and (3) have been established.

The management method for butt should be controlled in the steps of rolling, slitting, grooving and roll forming of strips, but the method of controlling the processing by detecting a variation factor should be adopted so far. Not. So far, we have relied on inspection and selection of strip dimensions and slit cross-sections, and have accepted practical tolerances (variations) in acceptable products.

The most important factors are the conditioning of the edges and the width of the edges and the circular shaping of the edges. Normally, this is done by taking measures to improve the accuracy of slit cutting and the accuracy of roll groove design for roll forming. For this reason, a method has been adopted in which, after the grooved rolling of the strip material is performed off-line, slitting processing of the plate width is performed on another line. Partly, a groove processing method for a strip material for circularly shaping an edge portion (for example, Japanese Patent Laid-Open No. 4-157017) is also proposed, but the width and end face shape of the strip material vary, and it is still insufficient. is there.

Therefore, even if the strip material grooved by the current grooving method is roll-formed and welded, the welding becomes unstable, and the welding strength decreases, and it is impossible to eliminate variations over time.

At present, as a heat exchange medium, preparations are being made to use CFCs that destroy the ozone layer and CFCs that substitute before they reach the ozone layer.

Unfortunately, the alternative CFC has a heat exchange characteristic of about 20%, so that measures must be taken against the urgent abolition of CFC.

Although it is necessary to increase the heat exchange area of the heat transfer tube as much as the heat exchange characteristics are deteriorated, a problem occurs in weight and size. Therefore, it is necessary to improve the performance of the heat transfer tube by compensating for the deterioration due to the CFC substitute. There is.

The present invention has been made in view of the above problems of the prior art, and its object is to:
Welding heat-transfer tube strip rolling that can improve the quality of welding by improving the butting condition by tubular forming by performing groove rolling without variation in strip width and edge shape An object of the present invention is to provide a welding flat heat transfer tube using an apparatus and a strip processed by the apparatus.

[0019]

In order to achieve the above-mentioned object, a rolling groove forming apparatus for welding heat transfer tubes according to the present invention is a groove forming apparatus in which a large number of groove forming projections are provided at a predetermined pitch. Section and a side edge rolling section provided on both sides thereof and a groove forming roll formed by a groove forming roll formed by a side edge rolling section and a supporting roll arranged to face the groove forming roll. Is symmetrical, and when the groove is formed, the ridges of the groove forming roll are pushed into the original strip material at the time of forming the groove, and when the groove is formed, the ridges of the volume of the strip member to be extruded to both sides of the ridge are formed. A buffer area for absorbing the fluctuation amount is provided at least at one place, and one or both of the grooved roll and the support roll is provided with a restraining portion for restraining the widthwise spread of the strip.

Further, it is preferable to similarly provide a buffer area for the strip member between the side edge rolling portion and the grooved ridge adjacent thereto.

In the case of producing a flat material for welded flat heat transfer tubes, the groove portion at a predetermined pitch position among the groove portions of the roll is made shallow and flat.

The welded flat heat transfer tube is made by inserting a corrugated inner fin into a welded inner surface grooved flat tube made of a strip material having a brazed portion of the corrugated inner fin made by a strip grooved rolling device. .

[0023]

When the strip forming roll presses the strip material, the groove-forming projections enter the strip surface and are grooved. At that time, the strip member pressed and pushed out of the groove portion flows to a portion where the strip material is not pressed to increase the thickness of the strip member, and fills the gap formed between the grooved projection strips so that the strip has a predetermined height. Form a ridge.

At this time, if the thickness t ₀ of the original strip material is larger than the reference value, the strip members that could not be inserted between the grooved ridges flow in the width direction of the strip material, and the width of the strip material is reduced. Although the width of the strip is to be expanded, the width of the strip is blocked by the restraining part, so that it is absorbed in the buffer area.

For this reason, the width of the strip becomes constant and the force acting on the end of the strip does not change so much. Therefore, the width of the strip is uniform and the grooved strip with no uneven end face shape. The material is obtained.

When a low ridge is provided at the center of the buffer area of the grooved roll, the low ridge prevents the ridge from bulging at the center of the buffer area, and the ridge members from both sides are removed. By allowing it to flow into the buffer area, it is possible to prevent unreasonable force from being applied to the ends of the strip.

When the buffer area is provided between the side edge rolling section and the grooved projection adjacent to the side edge rolling section, the strip member flowing from the side edge rolling section or the groove forming section can be absorbed. Therefore, the fluctuation of the force generated in the restraint portion is further reduced.

Since the strip material processing surface of the groove forming roll is symmetrical, the processed strip material has a symmetrical shape with its center line as the axis of symmetry. Since twisting etc. does not occur during tubular forming,
The abutting state of the abutting portion due to the tubular forming becomes uniform, which enables uniform welding.

Since the groove at the predetermined pitch position among the groove portions of the roll is shallow and the bottom is flat, the ridges of the strip material processed in this shallow groove portion are lower than the other ridges and the top surface of the strip is lower. Is formed flat and becomes the brazed portion of the corrugated inner fin.

Therefore, if a flat tube with a groove on the inner surface of a weld is produced using this strip and the corrugated inner fins are inserted therein,
Since the inner fins come into contact with the shallow brazed portions of the grooves, the inner fin-shaped welded flat heat transfer tube can be obtained by brazing the abutting portions.

[0031]

Embodiments of the present invention will be described with reference to the drawings.

Example 1 In FIGS. 1 and 2, 1 and 8 are groove forming rolls and supporting rolls in a strip groove rolling apparatus, 10 is an original strip,
Reference numeral 11 denotes a strip material which has been grooved and rolled.

In FIG. 1A, the groove forming roll 1 is composed of a groove forming portion 1A and side edge rolling portions 1B provided at both ends thereof, and the groove forming portion 1A is used to form a groove in the raw strip 10. A large number of grooved projections 2 having a pitch p, a height h ₂ , and an angle θ having a substantially trapezoidal cross section, and the central portion of the groove forming portion 1A, which is in contact with the surface of the raw material during the grooved rolling process. Low ridge 3
Is equipped with.

Further, in FIG. 1B, the side edge rolling section 1B is used.
Is composed of an end rolling portion 5 having a small diameter portion 7 and a slope portion 6 which are continuous with the base portion of the grooved ridge 2'at the end portion of the groove forming portion 1A. The width w ₂ of the small diameter portion 7 is equal to the width of the groove portion 4 in the groove forming portion 1A.
Of the width w _{1 of} .

The support roll 8 is provided at both ends with flanges 9 for preventing the widthwise extension of the strip that occurs during grooving.
The height of the flange 9 is the same as that of the end rolling portion 5 of the groove forming roll 1.
When the flange 9 comes into contact with the groove, the gap between the grooved projection 2'of the groove forming portion 1A and the surface of the support roll 8 becomes a predetermined thickness tmin of the groove 12 of the grooved strip 11. It has become.

Further, in FIG. 1C, the width of the small diameter portion 7'which is continuous with the base of the grooved ridge 2'in the side edge rolling portion 1B is the width w of the groove portion 4 in the groove forming portion 1A. Instead of being the same as ₁ , the diameter is smaller than the diameter of the groove 4.

The groove forming roll 1 and the supporting roll are arranged such that the flange of the supporting roll 8 is in contact with the end pressure contact portion 5 of the groove forming roll 1 constructed as described above, and both rolls are rotated to rotate the gap between them. Grooving is performed by passing the raw strip 10.

When the raw strip 10 enters between the rolls 1 and 8, the grooved projections 2 in the groove forming portion 1A of the roll 1 press the surface of the raw strip to a thickness tmin to form the grooves 12. To do.

The ridge member extruded from the pressing groove 12 by the ridge 2 increases the thickness of the adjacent portion to fill the groove portion 4 of the roll 1 to form the ridge portion 13 having the thickness tmax. The thickness t ₀ of the groove 4 is larger than the reference value or the like.
The strip member that could not enter the space moves in the width direction of the strip material and enters the gap g ₁ formed on both sides of the low protruding strip 3 provided at the center of the roll 1.

That is, the void portion g ₁ functions as a buffer area C ₁ for relaxing the extension of the strip 11 in the width direction.

Simultaneously with this grooving, both ends of the strip 11 are rolled by the end rolling portions 1B, but the extension of the strip 11 in the width direction by rolling is prevented by the flange 9 of the support roll 8. When pressed by rolling, the strip member extruded with a volume equal to or larger than the reference value as described above enters the gap g ₂ formed in the small diameter portion 7.

That is, the gap g ₂ also functions as a buffer region C ₂ for relaxing the extension of the strip 11 in the width direction.

According to this embodiment, since the extension of the strip in the width direction generated during the groove rolling is restricted by the supporting rolls and can be absorbed by the buffer areas C ₁ and C ₂ , the groove rolling is carried out. Even if there is some variation in the thickness, width, etc. of the original strip material at the end portions of the strip material 11, there is no variation in the width and end shape.

EXAMPLE As the groove forming roll 1, the pitch P of the grooved ridges 2 is 0.
55 mm, height h ₂ (= tmax-tmin) 0.16
mm, inclination θ about 10 °, thickness 0.3m
m, the width of the strip is 20.8 mm, and the raw strip made of phosphorous-deoxidized copper is grooved and rolled off-line, and the average groove pitch is 0.55.
mm, thickness tmax is 0.38, tmin is 0.22
A strip material having a groove angle of 10 ° was obtained.

This grooved strip was formed on the entire outer circumference by roll forming, rounded to a finished diameter of 6.35 mm, and the abutting portion was high-frequency welded by an electric sewing machine.

In the grooving rolling process, the width of the strip can be regulated to be constant and accurately, and the grooving can be performed.
° (conventional + 20 °, -0 °), step variation ± 0.25
It was possible to weld with mm (conventional ± 0.1 mm).

For this reason, the welding strength is greatly improved, the quality maintenance for a long time is improved to 1/50 Km (conventional 1/10 Km), the reliability of welding quality is greatly improved and stabilized, and the yield is also improved. It improved from 80% to 95%.

Therefore, the adjustment due to the material variation is small, and the operating rate is improved from 70% in the past to 95%.

Since the butt angle and the step difference are small, the life of the seam guide is extended from the conventional 100 hours to 400 hours, and the life of the squeeze roll is extended from 400 hours to 800 hours. Was greatly improved.

In the above embodiment, the buffer area C ₁ of FIG.
Although the buffer areas C ₂ and C ₃ shown in FIGS. 1B and 1C are provided at the side end portions in the central portion, any of the central portion or the side end portions C ₁ , C ₂ , C ₃ is provided. Also good.

In the above embodiment, the grooved ridges of the groove forming roll are formed in a ladder shape to form a groove in the ladder shape. However, the groove shape itself is free from the viewpoint of each manufacturer. ,
The following conditions should be met.

A. Be symmetrical, b. There is at least one continuous buffer area in the width direction of the groove forming roll in the length direction of the strip material, c. There are flange portions at both ends of the groove forming roll or the supporting roll that prevent the strip material from spreading in the width direction, d. The thickness te of the end of the strip is (tmax + tmin) /
2 ≧ te> tmin.

Embodiment 2 Referring to FIGS. 3 and 4, 1'is a groove forming roll of a strip material for an inner fin type flat heat transfer tube, and 4'is a shallow flat at a predetermined pitch position in the groove portion 4 of the roll 1 '. The groove formed on the.

Reference numeral 10 'is an aluminum strip, 11' is an aluminum strip processed by the roll 1 ', and 16 is a brazing strip formed by the groove 4'of the roll 1'.

Other configurations are the same as those of the roll 1 shown in FIGS. 1 and 2 of the first embodiment except that the roll width is slightly different. Therefore, the same parts are designated by the same reference numerals and their description will not be repeated. Is omitted.

Then, as in Example 1, the raw strip 10 '
Is rolled with a groove forming roll 1'to produce a strip 11 '. This strip 11 'is formed into a flat tubular shape on the entire outer circumference, and the abutting portions are welded by an electric resistance welding device to produce a flat tube with an inner groove.

5 and 6, the flat tube 15 with the inner groove is cut into a predetermined length (about 150 to 300 mm) so as to fit the length of the car cooler, and the flat tube 15 has inner and outer surfaces. The brazing agent 18 is applied, and the wavy fins 17 having substantially the same length as the brazing agent 18 are applied to both the projecting surfaces of the brazing fins 1 for brazing.
6 is inserted into the flat tube 15 so as to be in contact therewith.

Then, the flat tube 16 having the corrugated fins 17 inserted therein is heated in a furnace, and both projecting surface portions of the corrugated fins 17 are brazed to the brazing projections 16 on the inner surface of the flat tube.
Make a flat heat transfer tube with inner fin type inner groove as shown in (a).

Example As the groove forming roll 1, the pitch P of the grooved ridges 2 is 0.
55 mm, height h ₂ (= t _max −t _min ) 0.16 mm,
Using a material with an inclination θ of about 10 °, a raw material consisting of 3-layer clad aluminum with a plate width of 0.3 mm and a plate width of 42.2 mm was subjected to groove rolling processing offline, and the groove pitch averaged 0.5.
A strip material having a thickness of 5 mm, a thickness t _max of 0.38, a t _min of 0.22 and a groove angle of 10 ° was obtained.

This grooved strip was formed on the entire outer circumference by roll forming, and was rearwardly deviated to form a finished long diameter of 20 mm and a rectangle of 2 mm, and the abutting portion was high-frequency welded by an electric resistance welding device.

In the grooving rolling process, the width of the strip can be regulated to be constant and accurately and grooved, so that there is little variation in the butt due to the entire outer peripheral molding, and the butt angle ± 2 ° (conventional + 20 °, -0 °), step difference ± 0.025
It was possible to weld with mm (conventional ± 0.1 mm).

Therefore, the welding strength is greatly improved, the quality maintenance for a long time is improved to 1/50 km (conventional 1/10 km), the reliability of the welding quality is greatly improved and stabilized, and the yield is also improved. It improved from 83% to 98%.

Therefore, the adjustment due to the material variation is small, and the operating rate is improved from 72% to 97%.

Since the butt angle and the step difference are small, the life of the seam guide is extended from the conventional average of 350 hours to an average of 920 hours, and the squeeze roll life is extended from an average of 800 hours to an average of 3000 hours. The life of the product has been greatly improved.

In the above embodiment, the buffer area C ₁ of FIG. 4 (a) is provided in the central portion, and the buffer areas C ₂ , C ₃ of FIGS. 4 (b) and 4 (c) are provided at the side end portions. Or buffer areas C ₁ , C ₂ , C at the side edges
Any of the _three may be provided.

Further, in the above embodiment, the groove-forming ridges of the groove forming roll are formed in a ladder shape to form a groove in the ladder shape. However, the groove shape itself is the idea of each manufacturer. It suffices if the following conditions are met.

A. The groove shape should be bilaterally symmetric, but the finned part should not be symmetrical.

B. At least 1 in the middle direction of the groove forming roll
There shall be a continuous buffer area in the length direction of the strip material.

C. There must be flanges on both ends of the groove forming roll or the support roll that prevent the material from spreading in the middle direction.

[0070]

Since the present invention is configured as described above, it has the following effects.

(1) A grooved strip material having a uniform width and no unevenness in the end face shape can be absorbed in the buffer area to absorb the widthwise extension of the strip member which spreads in the width direction of the strip material. Can be continuously processed.

(2) Since the grooved strip does not twist when formed into a tubular shape, the ends can be abutted uniformly, and uniform welding can be performed.

(3) Therefore, the reliability and yield of the weld heat transfer tube are improved, and the operating rate of the welding heat transfer tube manufacturing apparatus is improved.

(4) Since there is no variation in the welded portion,
The life of consumables such as seam guides and squeeze rolls is greatly improved.

(5) By using a flat heat transfer tube in which corrugated fins are inserted in the flat tube with groove on the inner surface, it is possible to obtain an effect of improving heat exchange characteristics by 20% or more as compared with the conventional flat heat transfer tube having no groove on the inner surface. Was given.

[Brief description of drawings]

1A, 1B, and 1C are cross-sectional views showing a groove forming process state and a side edge rolling process state according to a first embodiment.

2 (a) and (b) are cross-sectional views showing an original strip and a strip-rolled strip according to Example 1. FIG.

3A, 3B, and 3C are cross-sectional views showing a groove forming process state and a side edge rolling process state according to the second embodiment.

4 (a) and (b) are cross-sectional views showing an original strip and a strip-rolled strip according to Example 2. FIG.

5A and 5B are cross-sectional views of a main part of the flat heat transfer tube and an enlarged view of a main part of the inner fin according to the second embodiment.

FIG. 6 is an explanatory diagram of inserting the inner fin according to the second embodiment.

FIG. 7 is a schematic view showing a method for manufacturing a welded heat transfer tube with an inner groove.

8A, 8B and 8C are sectional views showing a conventional heat transfer tube for a car cooler.

[Explanation of symbols]

 1, 1 '... Groove forming roll 1A ... Groove forming part 2B ... Side edge rolling part 2, 2' ... Groove for groove 3 ... Ridge 4 ... Groove part 5 ... End rolling part 6 ... Slope part 7 ... Small diameter part 8 ... Support roll 9 ... Flange 10, 10 '... Original strip material 11 ... Strip material 12 ... Groove 13 ... Welding heat transfer tube 14 ... Inner fin type flat grooved inner surface heat transfer tube 15 ... Inner grooved flat tube 16 ... For brazing Ridges 17, 28, 29 ... Wavy fins 18 ... Lotion agent 21 ... Groove rolling part 22 ... Tubular forming part 23 ... ERW welding device 25 ... Harmonica pipe 26 ... Inner fin pipe 27 ... Flat pipe

Claims (5)

[Claims] 1. A groove forming roll comprising a plurality of grooved projections provided at a predetermined pitch and side edge rolling parts provided on both sides of the groove forming roll, and the groove forming roll is arranged to face the groove forming roll. In the case of rolling a groove into a strip with a support roll, the strip forming surface of the groove forming roll is left-right symmetric, and the groove forming part is provided with a buffer area with a void in at least one place. And one or both of the support rolls are provided with a restraint portion for restraining the widthwise spread of the strip, and a strip groove rolling apparatus for a welded heat transfer tube. 2. A strip rolling apparatus for welding heat transfer pipe according to claim 1, characterized in that a low ridge which is in contact with the surface of the raw strip is provided at the center of the buffer zone of the grooved roll. . 3. A weld heat transfer pipe strip according to claim 1, wherein a buffer area having a gap is provided between the side edge rolling portion and the grooved projection strip adjacent thereto. Rolling machine with material groove. 4. A grooved portion of a roll grooved portion at a predetermined pitch position is formed to be shallower and flatter than other grooved portions, and a brazed portion of a corrugated inner fin is formed on a strip material. 3. A rolling device with a groove for a welding heat transfer tube according to any one of 3 to 3. 5. A corrugated inner fin is inserted into a flat tube with a groove on a welded inner surface using a strip material rolled by the strip material rolling apparatus for a weld heat transfer tube according to claim 4. Welded flat heat transfer tube.