JPS642448B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for manufacturing an inner groove tube used in a heat exchanger such as a cooler, and provides a manufacturing method particularly suitable for mass production with high processing speed. It is something.

[Problems to be solved by conventional technology and invention]

In general, in order to increase the efficiency of heat exchangers such as coolers, inner groove tubes with many fine grooves formed on the inner surface of the tube are used, and are conventionally manufactured by forging, drawing, rolling, etc. In order to mass produce such inner groove tubes, a processing speed of 50 to 100 m/min is desired. As shown in FIG. 1, the forging method involves rotating a forging roll 2 rotating around a grooved plug 1, inserting a metal pipe 3 between the plug 1 and the forging roll 2, and pulling it out. Many grooves are formed on the inner surface, and the processing speed is quite slow at 5 to 25 m/min, making it unsuitable for mass production. The drawing method forms a large number of grooves on the inner surface of the pipe by drawing the metal pipe using a die and a grooved plug.The drawing method has a high processing speed and is suitable for mass production, but the depth of the grooves obtained is limited. However, there is a drawback that the efficiency of the heat exchanger cannot be sufficiently increased. In addition, the rolling forming method involves gradually bending a metal strip with grooves formed in advance using forming rolls and presser rolls arranged in multiple stages, forming it into a tubular shape one after another, and then welding the joints, resulting in a high processing speed. Although it is suitable for mass production, it has the disadvantage that the groove is crushed by the presser roll during bending.

[Means and actions for solving the problem]

In view of this, as a result of various studies, the present invention has developed a manufacturing method for internal groove tubes that has a high processing speed and is suitable for mass production.The method of the present invention is to gradually bend a metal strip using forming rolls and presser rolls arranged in multiple stages. In a method of manufacturing a pipe in which the joints are welded after being processed and formed into a tubular shape one after another, a large number of protrusions are provided on the surface of each presser roll in a predetermined width at sequentially changing positions, and only the portion where the protrusions are located is used. is in contact with the surface of the metal strip, and is supplied to the forming roll and presser roll group, and has grooves partially formed in advance, or a metal strip with a smooth surface without groove processing. It is characterized in that it is gradually bent into a tubular shape using each forming roll and a presser roll, and the inner surface of the tubular body is sequentially grooved by a predetermined width using each presser roll.

That is, in the present invention, the rolled metal strip is
In the conventional method of sequentially bending in the width direction using forming rolls and presser rolls provided in stages to form a tube, a large number of grooving ridges are formed in a predetermined width by sequentially changing the position on the surface of the presser roll in each stage. By sequentially bending the rolled metal strip P in the width direction in five stages as shown in FIGS. 2 a to 3 e and 3 a to e, the inner surface of the tube of the strip P is Grooving G of a predetermined width is sequentially performed, and grooves are formed on the entire inner surface of the tube until the final machining (Fig. 2 e and Fig. 3 e).
The seam W of the strip plate P bent into a tubular shape is welded to produce an inner groove tube.

The angle of the groove with respect to the direction of movement of the metal strip is 0~
The grooves can be formed at an angle of 90°, but in order to prevent the strip from escaping to the left or right due to horizontal force during groove machining, the groove angles should be set in opposite directions relative to the center of the strip. It is best to balance it as Furthermore, weldability is better when the edges of the strips to be welded are not grooved, and blowholes are less likely to occur.

Next, examples of the present invention will be described.

〔Example〕

An inner groove tube with an outer diameter of 12.7 mm was manufactured by sequentially bending pure copper strips with a thickness of 0.4 mm and a width of 39.0 mm in the width direction according to the steps shown in Fig. 2 a to e and Fig. 3 a to e. . A height of 0.3 mm is applied to each tier of presser rolls from both sides of the strip, corresponding to 5 mm each.
A protrusion with a depth of 0.3 mm, a pitch of 0.3 mm, and an inclination of 30 degrees is formed, and the strip is gradually bent. At the same time, a groove with a depth of 0.3 mm, a pitch of 0.3 mm, and an inclination of 30 degrees is partially formed on the inner surface of the tube. In the final step, grooves were formed on the entire inner surface of the tube, the tube was formed into a tube shape, and the mating surfaces were welded. As a result, an inner groove tube with 130 grooves, a groove depth of 0.3 mm, a groove angle of 30°, and an outer diameter of 12.7 mm was obtained.
The processing speed at that time was 50 m/min.

In addition, in the above-mentioned inner groove tube, the welding finish was better when the 0.2 to 0.5 mm of the edge of the strip plate corresponding to the welded portion was not grooved.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to easily create an inner groove tube with sufficient groove depth and high thermal efficiency.
Furthermore, mass production is possible with greatly improved machining speed, and the process is significantly more effective than conventional methods.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a method for manufacturing an inner groove tube using a conventional forging method, and FIGS. 2 a to 3 e and 3 a to 3 e show variations of the strip plate in the forming process according to the method of the present invention. FIG. 2 is a front view, and FIG. 3 is a plan view. 1... Grooved plug, 2... Forged roll, 3...
Pipe, P... Band plate, G... Grooving area, W...
welded part.

Claims (1)

[Claims] 1. In a tube manufacturing method in which a metal strip is gradually bent into a tubular shape using forming rolls and presser rolls arranged in multiple stages, and the joints are welded, A large number of protrusions are provided in a predetermined width so that only the portions where the protrusions are located are in contact with the surface of the metal strip, and the metal strip is supplied to the forming roll and presser roll group, with grooves being partially formed in advance. A metal strip with a smooth surface that has not been processed or grooved is gradually bent using each forming roll and a presser roll to form it into a tubular shape one by one. 1. A method for manufacturing an inner groove tube, characterized by sequentially grooving the tube to a predetermined width.