JPS6012220A - Production of metallic tube - Google Patents

Abstract

PURPOSE:To obtain continuously a metallic tube having a weld zone in a flat part by deforming a cylindrical tube to a sectional shape of which the weld zone mas a min. radius of curvature then shaping the tube to a sectional shape having a large radius of curvature. CONSTITUTION:A plate-shaped hoop is formed by rolling to a cylindrical shape and is heated to melt by using a high frequency. The heated part is pressed with squeeze rolls and is thus welded. The bead on the surface after the welding is machined and the weld spatter and debris are removed with a cleaning device. The pipe is then deformed to the sectional shape of which the weld zone has a min. radius of curvature by means of rolls 8 which shape the pipe to a section having rounded angles with a rhombic shape and thereafter the pipe is shaped to a sectional shape in which the weld zone 12 is flat or has a relatively large radius of curvature. An intended flat tube 9 is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a method of manufacturing metal tubes, and more particularly to a method of manufacturing metal tubes in which the weld is located on a relatively flat portion of the tube.

BACKGROUND OF THE INVENTION For example, flat welded brass tubes are used as water tubes constituting heat exchangers for automobiles. It is known that in terms of mechanical strength, it is better for the welded portion of such a flat weld tip to be located on a flat cross-section of the tube rather than on a curved cross-section of the tube. However, flat tubes in which the welded portion is located on a flat cross section of the tube have the following problems, making it difficult to put them into practical use.

FIG. 1 is a diagram for explaining the manufacturing process of a flat welded tube. Weld. The thus-formed perfectly circular tube is bead-cut with a bead cutter 6, cleaned with a cleaning device 7, and then shaped into a flat welded tube 9 with a group of shaping rolls 8. FIG. 2 shows how the tube 10 passes through the squeeze roller 5 and some of the shaping roll group 8.
5 is shaped into a perfect circle (FIG. 2(a)), an elliptical shape (FIG. 2(b)), and then a flattened chive 9 (FIG. 2(C)). In this process, even though the welded part 11 is softened by the influence of heat from welding and is relatively easy to bend, parts other than the welded part that are easy to bend are bent. ), as shown in (e), the welded part 12
The position of is likely to fluctuate. This positional variation causes a variation in the position of the free end 11 to be welded, as shown in FIG. 2(a), causing unstable welding and external bead cutting.

Purpose of the Invention In view of the above-mentioned prior art, the present invention provides stable welding and an external bead when continuously manufacturing a welded metal tube having a welded portion in a flat or relatively large radius of curvature cross section. It is an object of the present invention to provide a practical method for manufacturing a welded metal tube of the type described above.

Structure of the Invention In order to achieve the above object, the present invention roll-forms a flat strip material into a round shape, and in the roll shaping after welding, first deforms the welded part into a cross-sectional shape having an extremely small radius of curvature. The weld is then shaped into a cross-sectional shape that is flat or has a relatively large radius of curvature.

FIG. 3 is an enlarged view of the tube welding station, and when forming the circular tube 10 by heating with the heating coil 4 and pressure welding with the squeeze roller 5, welding position 11 of the strip material is shown.
In order to position the squeeze roller 5 at the center position,
A guide sea 14 is arranged in front of the heating coil 4 (connected to the high frequency oscillator 13). However, in the case of hard-walled tubes with a plate thickness of 0.15 mm or less, welding position 1
Fluctuations of 100.1 to 0.3 inches greatly reduce welding quality, so in order to obtain stable welding, it is important that the position of the welded part 12 does not fluctuate in the process after passing through the squeeze roller 5. . However, the shaping roller group 8
When shaping is performed, the position of the welded portion 12 changes as shown in FIG. 2 due to roll runout of about 10 μm, tube vibration, etc.

This occurs because the welded portion 12 tends to move to the curved section of the tube during shaping because the vicinity of the welded portion is softened by the action of heat and becomes easily bent.

Therefore, variations in the position of the welded portion during shaping do not actually pose a problem in the manufacture of tubes in which the welded portion is located at the minimum curvature portion. Therefore, in the present invention, after the tube is welded, a special shaping step is provided so that the welded portion becomes a minimally curved portion. Due to the existence of such a shaping process, the welded portion 12 is held in a predetermined position during tube welding, allowing stable welding.

The cross-sectional shape of the tube to which the present invention can be applied is
In addition to cases where there is a weld on the flat part of a flat shape as shown in the figure (,), for example, when there is a weld on the short axis of an ellipse, a flat part of the cross section or a part with a relatively large radius of curvature. This is the case where there is a welded part. In addition, the material of the tube can be brass, aluminum, copper, or any other metal that can be easily welded.

Example of the invention Brass (30% copper) with plate thickness o, iam, plate width 291nrIL
] Flat part length 11mm from plate-shaped building material, 5 curved parts radius 1mrn
Manufactures welded flat chives. The only difference from the conventional method is the shaping process after the plate-shaped material is deformed into a cylindrical shape and welded, that is, the shaping roll group 8 in FIG. 1. The strip material uncoiled from the uncoiler 1 is formed into a cylindrical shape using a total of six stages of round forming rolls 3, heated and melted using a heating coil 4 using a high frequency of 200 to 400 kHz, and then welded by applying pressure using a squeeze throw 25. do. After welding, a bead cutter is applied to cut the bead on the surface, and the cleaning device 7 removes the welding spots A? that have adhered to the tube surface. Clean off chips from ivy and bead cutting. Then the fourth
Three or four stages of shaping rolls are installed in a diamond-shaped cross section with rounded corners as shown in Figures (b) and (c). The radius of curvature of the curved portion of these rolls is about 1 to 10111111, and the opening angle of the curved portion of the roll that receives the weld is 900 to 12o0. Thereafter, it is passed through rolls as shown in FIG. 4(d) in order to obtain the desired flat tube 9.

As a result, as shown in FIG. 4(d), a flat tube having a welded portion 12 on the flat part is obtained, and moreover, as shown in FIG.
, ), there was no positional fluctuation of the welded portion 11 in the squeeze roller 5, and as a result, stable welding and external bead cutting were achieved.

Effects of the Invention As is clear from the above description, the present invention has practical advantages in the continuous production of metal chives from flat strips in which welds exist in large curvature radius or flat parts. A method is provided.

[Brief explanation of drawings]

Figure 1 is a schematic side view illustrating an apparatus for manufacturing chives from flat strip material, Figure 2 is a diagram showing a series of roll shaping operations in the prior art, and Figure 3 is an enlarged view of the welding station in Figure 1. 4 are diagrams showing a series of roll shaping operations according to the present invention. DESCRIPTION OF SYMBOLS 1... Uncoiler, 2... Flat strip material, 3... Round forming o-le 9p, 4... Heating coil, 5... Squeeze roller, 8... Shaping roll group, 9... ...Deformed tube, 11°12...Welded part, 14...Guide shoe. Patent Applicant Nippondenso Co., Ltd. Patent Application Representative Patent Attorney Akira Aoki Patent Attorney Kazuyuki Nishidate Patent Attorney Tetsu Koga Patent Attorney Akira Yamaguchi Procedural Amendment (Voluntary) August 72, 1980 Commissioner of the Japan Patent Office Wakasugi Kazuo 1, Indication of the case 1982 Patent Application No. 118235 2, Name of the invention Method for manufacturing metal tubes 3, Relationship with the person making the amendment Name of the patent applicant (426) Nippondenso Co., Ltd. 4, Agent (3 others) 5. Subject of amendment (11 "Detailed Description of the Invention" column (2) of the specification) Figures 1, 2, 3 and 4 of the drawings 6, Contents of the amendment ( 1) Amend "11" to "12" in the 6th line of page 3 of the specification. (2) Amend Figures 1 to 4 of the drawings as shown in the attached sheet. 7. Corrected drawings for catalog of attached documents (Fig. 1, Fig. 2, Fig. 3, Fig. 4) 1 copy Fig. 2 (a) (b) (c) Fig. 4 (a) (c) (b) , K”+ 1 (d )

Claims (1)

[Claims] successively supplying a flat metal strip, roll forming the strip into a cylindrical shape having mutually opposing free ends, welding the free ends to form a cylindrical tube, and A metal tool is used to further shape the cylindrical tube with rolls.
In the method for manufacturing tubes, in the roll shaping after welding, the cylindrical tube is first deformed into a cross-sectional shape in which the welded portion has a minimal radius of curvature, and then the welded portion has a flat or relatively large radius of curvature. A method characterized by shaping the material into a cross-sectional shape.