JPH02207918A - Manufacture of heat transfer tube - Google Patents

Abstract

PURPOSE:To easily curve a metallic band plate in a roll-forming stage by performing a grooving work through a stage to form inclined groove lines and a stage to form straight grooves having specified lead angles or projection lines. CONSTITUTION:First of all, the metallic band plate 1 is fed from a coil to be passed between rolls 2, 2'. For the upper roll 2 are used inclined grooves having inclined lead angles to the feeding direction of the metallic band plate 1, and straight or nearly straight grooves or marked projection lines having lead angles <=10 deg. each to the feeding direction at the same time or at another stage and a process condition capable of forming inclined groove lines 3 and straight groove lines 4 on the metallic plate 1 at the same time is set. A curved tubular body 6 is formed through plural stages of forming rolls 5 as the surface of the metallic band plate 1 is kept inside where inclined groove lines 3 and straight groove lines 4 are formed through between the rolls 2, 2'. The butted parts of the tubular body 6 are welded by a welder 7 at the following stage and finally drawn by a drawn bench 8 to manufacture a heat transfer tube 9 having a grooved inside.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a heat transfer tube having an internally grooved structure for use in heat transfer devices such as evaporators and condensers.

[Prior Art] Conventionally, in heat transfer devices involving boiling and condensation, heat transfer tubes made of copper material with spiral grooves formed on the inner surface have been widely used as heat transfer tubes with high heat transfer efficiency and low pressure output. In addition, as a type with particularly improved condensation heat transfer performance, a heat transfer tube with a structure in which a portion that is difficult to get wet has been developed so as to intersect with the spiral groove (Japanese Patent Publication No. 57-41675, etc.) has been developed.
.

The inventors have made further improvements to the prior art described above, and have developed a technology in which a metal plate is grooved with flat portions left on both ends, formed into a tubular shape with the grooved surface facing inside, and then the abutting portions are welded. He was the first to propose a method for manufacturing heat tubes (patent application 1986-5).
No. 7058, No. 63-261154).

[Problem to be solved by the invention]

However, in the above-mentioned technology, the manufacturing process in which the metal plate material with inclined grooves is not smoothly bent to form it into a tubular body with spiral grooves carved on the inner surface using forming rolls is difficult. I had the above problem.

The present invention solves this problem and provides a method for manufacturing an internally grooved heat exchanger tube that facilitates bending in the roll forming process.

[Means to solve the problem]

That is, the method for manufacturing a heat exchanger tube provided by the present invention is to groove a metal strip on one side while feeding it, form it into a tubular body, and then butt weld both effa&& to form a grooved inner surface. In the method for obtaining a heat exchanger tube, grooving is performed by forming an inclined groove line having a lead angle oblique to the feeding direction of the metal body plate, and simultaneously or in a separate process with respect to the feeding direction. This is carried out through a step of forming a straight or substantially straight groove or protrusion having a lead angle of 10° or less overlapping the inclined groove surface, and then forming the inclined groove and the straight or substantially straight groove or protrusion. The structure is characterized in that it is roll-formed into a tubular body with the surface on which the protrusions are formed facing inside.

Copper or aluminum is effectively used as the material for the metal strip from the viewpoint of workability, heat conductivity, etc.

The grooving process is performed through a step of forming an inclined groove and a step of forming a straight or substantially straight groove or protrusion.

Among these, the slanted grooves are formed in a process in which a metal strip continuously fed from a coil is passed between an upper roll having slanted grooves and a lower roll having a smooth surface.

The linear or substantially linear grooves or protrusions have a lead angle of 10' or less with respect to the feeding direction of the metal strip, that is, 0 to lO
Conditions must be set so that the lead angle is formed overlapping the inclined groove surface within an angle range of 10.degree., and if this lead angle exceeds 10'', the effect of bending the tube body will be diminished.

In order to form these grooves or protrusions in the same process as the inclined grooves, a method can be adopted in which a pattern for forming grooves or protrusions in the above lead angle range is created on a roll for forming the inclined grooves. In order to form it in a separate process, a roll with a pattern of only straight or nearly straight grooves or protrusions is installed before or after the roll for forming inclined grooves, or a suitable embossing means other than a roll is used. It can be done using force 5.

Further, the shape of the grooves or protrusions described above may be continuous, intermittent, or partial, but it is preferable to form them as a plurality of grooves.

The process of forming the tubular body is carried out by bending the grooved metal strip using forming rolls with the processed surface facing inside.

Next, the abutted portions of both end edges of the formed tubular body are welded. Various welding methods can be used such as TIG welding, MrG welding, electron beam welding, and high frequency welding, but among these, arc welding such as TIC and MIG, which does not require removal of the weld bead during drawing, is used. The application of is most preferred.

The tubular body after welding is finally drawn to obtain a heat exchanger tube having an internally grooved structure.

In addition, in the above process, by grooving both ends of the metal strip leaving a flat part of the same height as the groove bottom, and then processing and welding it into a tubular body, the inner surface as in the invention of Shioma No. 63-57058 is formed. It goes without saying that a heat exchanger tube having protrusions can be obtained.

[For production]

According to the present invention, the linear or substantially linear grooves or protrusions formed in the grooving process are used to smooth the bending of the metal strip in the subsequent tubular body forming process. Functions effectively. Therefore, machining accuracy is not impaired even if the feeding speed is increased, so machining efficiency is significantly improved.

Moreover, it does not inhibit the heat transfer effect of the inclined grooves, but rather also exhibits an effect that contributes to an increase in heat transfer performance.

〔Example] Hereinafter, the present invention will be explained based on examples.

Example 1 A heat exchanger tube was manufactured using a metal band plate made of phosphorus-deoxidized copper having a width of 25 mm and a thickness of 0.5 mm using the apparatus shown in FIG.

First, the metal strip 1 was fed from the coil and passed between the rolls 2.2''. The upper roll 2 has an inclined groove with a lead angle of 20' and a straight groove with a lead angle of 0° with respect to the feeding direction of the metal strip. We set process conditions that allow the formation of straight grooves and straight grooves at the same time.

The embodiment shown in FIG. 1(a) is a pattern in which the inclined grooves are symmetrically developed from the center line and four straight grooves are formed, and the embodiment shown in FIG. This figure shows an example in which a typical inclined groove and three straight grooves are simultaneously formed on two metal strips.

The metal strip, which has passed between the rolls 2.2 and has the inclined grooves 3 and straight grooves 4 formed on its upper surface, is then bent through multiple stages of forming rolls 5 and formed into a tubular body 6. Ta. In the next step, the tubular body 6 was welded at the butt portions using a welding machine 7, and finally drawn using a drawing machine 8 to produce a heat exchanger tube 9 having an internally grooved structure.

In the above process, the metal strip after being grooved is turned into a tubular body 6.
The forming process progresses significantly more smoothly than the conventional technology that does not form straight grooves, and even when the feeding speed of the metal strip l is increased, no deterioration in processing accuracy or other processing defects are observed. There wasn't.

Example 2 The same steel material as in Example 1 was used as a metal band plate L, and a roll 2 for forming inclined grooves as shown in FIG. 2 and a substantially linear groove (
Article 5) A heat exchanger tube with an internally grooved structure was manufactured using a device equipped with a forming roll 2''.

In this case, the lead angle of the groove with respect to the feeding direction of the metal strip l was 20' for the ll11 diagonal groove 3 and 5° for the substantially straight groove 4. Other conditions were the same as in Example 1.

In the above manufacturing process as well, it was confirmed that the bending of the tubular body 6 proceeded extremely smoothly due to the interposition of the substantially straight grooves 4, as in Example I.

〔Effect of the invention〕

As described above, according to the present invention, the process of bending a metal strip into a tubular body after grooved processing is significantly improved. The production efficiency can be effectively improved.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are perspective views illustrating an apparatus for carrying out the method of manufacturing a heat exchanger tube according to the present invention, and FIG. 2 is a perspective view illustrating another embodiment of the apparatus. l...Metal strip plate 2.2°, 2''...Roll 3
...Slanted groove 4...Straight groove, approximately straight groove 5
... Forming roll 6 ... Tubular body 7 ... Welding machine
8...Drawing machine 9...Heat transfer tube

Claims (1)

[Claims] 1. A method in which a metal strip is fed and grooved on one side, formed into a tubular body, and then butt welded at both ends to obtain a heat exchanger tube with internal grooves. , the grooving process includes a step of forming an inclined groove with a lead angle oblique to the feeding direction of the metal strip, and a step of forming a lead angle of 10° or less with respect to the feeding direction at the same time as this step or in a separate step. The step of forming straight or substantially straight grooves or protrusions on the inclined groove surface, and then forming the surface on which the inclined grooves and the linear or substantially straight grooves or protrusions are formed. A method for manufacturing a heat exchanger tube, characterized by roll forming it into a tubular body. 2. The method for manufacturing a heat exchanger tube according to claim 1, wherein a plurality of linear or substantially linear grooves or protrusions are formed continuously, intermittently, or partially in the inclined groove surface.