JPH01202329A - Manufacture of heat transfer tube - Google Patents

Abstract

PURPOSE:To improve the heat transfer efficiency of a heat transfer tube by intermittently delivering a metal strip sheet, slowing forming a groove on the strip sheet surface as well and joining the strip sheet by rounding in the width direction. CONSTITUTION:The cross rolling mill 3 consisting of a flat die 30 and work roll 31 is provided on the intermediate position of an uncoiler 1 and feeding rolls 4, 4 and a metal strip sheet 2 is intermittently delivered on about 30mm each between the die 30 and roll 31. Numerous projecting bars 3a are formed on one part of the peripheral face of the work roll 31 and the gap (b) with the flat die 30 is formed narrower toward the front part direction. The roll 31 is turned by moving it in the width direction on each the intermittent delivery of the strip sheet 2. A groove 21 is thus formed on the strip sheet 2 and the width is enlarged with rolling. The strip sheet 2 is then subjected to pipe making welding with delivering the strip sheet 2 from a coil 6 and a heat transfer tube (a) is formed. The heat transfer efficiency of the heat transfer tube (a) is improved by the deep and correct groove 21.

Description

Detailed Description of the Invention: "Industrial Application Field" The present invention relates to a method for manufacturing a heat exchanger tube having grooves or protrusions on the inner or outer surface, and is particularly used in heat exchangers such as evaporators or condensers. The present invention relates to a method for manufacturing a heat exchanger tube.

"Prior art" Conventional methods for manufacturing this type of heat exchanger tube include, for example,
As disclosed in Japanese Patent No. 4-37058, a plug having a predetermined groove or protrusion on the circumferential surface is inserted into the metal tube while feeding the metal tube in the axial direction by drawing, and the outer periphery of the metal tube is A so-called rolling method in which a metal strip is compressed by a plurality of planetary rotating rolls or balls; and 1. As disclosed in JP-A-55-43360, for example, a metal strip is rolled out and grooves or protrusions are formed on the circumferential surface. After forming grooves or protrusions on the surface of the metal strip through the metal strip between the processing roll and the rolling roll that is pressed against the processing roll, the metal strip is rolled in the width direction and both sides are welded. In the latter manufacturing method, there is also a method in which grooves or protrusions are formed on the surface of the metal strip using a cutting tool instead of the processing roll described above.

"Problem to be solved by the invention" Among the above-mentioned conventional techniques, the former involves, prior to manufacturing the heat exchanger tube,
In addition to the high cost of producing small-diameter, thin-walled metal pipes by drawing them multiple times, it is also difficult to form grooves with complex cross-sectional shapes. When cutting grooves on the surface of
It is difficult to form deep grooves, especially in hard and difficult-to-process materials such as titanium and stainless steel.

In addition, the latter method, in which grooves are formed on a metal strip using a medium-term cutting tool, has a poor yield, and moreover, it is difficult to form grooves on thin metal plates or hard materials that are difficult to machine.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a heat exchanger tube that improves the above-mentioned problems.

"Means for Solving the Problems" In order to achieve the above-mentioned object, the method of the present invention is to apply a metal strip to a predetermined length onto the upper surface of the flat die of a cross rolling mill consisting of a flat die and a work roll having the following structure. A step of gradually forming a groove of a predetermined depth on the surface of the metal strip while intermittently feeding out the metal strip, and rolling the metal strip in the width direction with the groove inside or outside the groove, and rolling the metal strip on both sides thereof. The process of forming a pipe by joining the sides was adopted.

The work roll is located above the flat die and has a large number of protrusions parallel to the circumferential surface of the work roll along the axis of rotation and the direction in which the metal strip is fed out. The gap between the flat die and the upper surface of the flat die becomes narrower toward the front in the direction of contact with the edge of the metal strip, and each time the metal strip is fed out intermittently, the metal strip is pressed against the upper surface of the metal strip. It is configured to rotate while moving in the width direction.

``Operation'' When a metal strip is rolled intermittently in a cross rolling mill with the structure described above, the gap between the work roll and the top surface of the flat die becomes narrower as the distance to the rear of the metal strip in the feeding direction increases. Because of this, the grooves formed in the metal strip are shallow at first, and gradually become deeper each time they are fed out intermittently.

``Example'' The drawings illustrate an apparatus for carrying out the method of the present invention. For example, a metal band plate 2 made of titanium with a width of 40 mm and a wall thickness of 0.7 cm held by an uncoiler 1 is A pair of intermittent feed rolls 4.4 intermittently feeds out a length of 3 hm at a constant speed.

A cross pressure ff1 consisting of a flat die 30 and a work roll 31 whose rotation axis is along the direction in which the metal strip 2 is fed out is placed between the installation positions of the uncoiler 1 and the feed roll 4.4.
m3 is provided, and the metal strip 2 is fed out while being sandwiched between the flat die 30 and the work roll 31.

The work roll 31 has, for example, a large number of parallel protrusions 3a in a spiral shape on a part of its circumferential surface (a part that does not come into contact with a backup roll 32, which will be described later) during driving, as shown in FIGS. 1 and 2. , the gap with the lower flat die 30 is inclined forward in the feeding direction so that it becomes narrower from the rear position of the metal strip 2 toward the front position (right end in FIG. 2), and the metal strip 2 is 30 mm. As shown in FIG. 3, as shown in FIG. It is pressed and rotates. That is, for example, it rotates while moving horizontally from the position A in FIG. 3 to the position B in the same figure (or from the position A in the same figure to the position B and then back to the position A).

In this embodiment, a backup roll 32 is provided above the work roll 31, and the work roll 31 is configured to move horizontally along a guide frame 33 via the backup roll 32 as shown in FIG.

Further, in this embodiment, when the metal strip 2 is intermittently fed out five times or once every 30 mm, the corresponding portion of the metal strip 2 passes below the work roll 31.

Therefore, when the metal strip 2 is intermittently transferred to the position of the work roll 31 by the above-mentioned length, the surface of the corresponding portion of the metal strip 2 initially has the shape shown in FIG. 4(a). Although only a shallow and narrow groove 21 is formed as shown in FIG.
As the grooves 21 gradually become deeper and wider, the cross-sectional shape of the grooves 21 gradually becomes more accurate, and at the same time, the width of the metal strip 2 increases due to rolling.

In the process of forming the grooves 21 in this way, the work roll 31 moves in the width direction of the metal strip 2, and in the next step, the metal strip 2 is paid out to a predetermined length and the work roll 31 is moved.
When moving in the width direction, it is designed so that it is guided by the protrusions 3a of the work roll 31 or the grooves 21 that are being formed on the surface of the metal strip 2.

After forming the grooves 21 on the surface of the metal strip 2 as described above,
It is desirable to guide the metal strip 2 to the cleaning tank 5 using guide rollers 51, 52, 53, and wash the metal strip 2 to remove dirt, oil, etc. attached thereto.

Thereafter, the metal strip 2 is wound onto a winding drum 6, and the winding drum 6 that has been wound is transferred to the next pipe-making process.

In the pipe making process, metal strips 2. While continuously feeding out the metal strip 2, the edges 22 at both edges of the metal strip 2 are cut out to a width of 50 mm using a roll cutter 7.7, and then two forming rolls (not shown) are used to cut the metal strip 2 so that the groove 21 is on the inside ( or outside) and roll it in the width direction,
The heat exchanger tube a is manufactured by welding both sides of the metal strip 2 using a suitable welding means 8.

This heat exchanger tube a is shaped into a more perfect circle by passing it through a finishing die (not shown) and drawing it dry.
The diameter is reduced to form a heat exchanger tube a with an outer diameter of 15.88 mm.

In the embodiment described above, the groove 21 was formed in the metal band plate 2 and then the metal band plate 2 was wound onto the winding drum 6, but this winding may be omitted and the metal band plate 2 may be subsequently formed into a pipe.

In addition to TIG welding and high frequency induction welding, other known welding methods can be used for welding during pipe manufacturing.

Further, two similar work rolls 31 with different directions of the protrusions 3a are arranged before and after the method of feeding out the metal strip 2, and the respective work rolls 31 have different directions on the surface of the metal strip 2. Grooves 21 may be formed. In this case, the grooves 21 are formed to intersect, and the portion surrounded by the grooves 21 becomes a protrusion.

Furthermore, in the embodiment, the work roll 31 is cut into a flat die 3.
0, the gap between the work roll 31 and the top surface of the flat die 30 becomes narrower toward the front in the feeding direction of the metal strip 2. However, instead of this structure, The rotational axis of the work roll 31 is made horizontal, and the top surface of the flat die 30 is tilted so that the gap between the work roll 31 and the top surface of the flat die 30 becomes narrower as it moves toward the front in the direction in which the metal strip 2 is fed out. It can be implemented even if it is configured as follows. For example, as shown in FIG. 5(a), the rotation axis of the work roll 31 is made parallel to the flat die 30, and the work roll 31 is made into a conical shape whose diameter becomes larger as the work roll 31 moves toward the front in the direction in which the metal strip 2 is fed out. It is also possible to provide the platform 3b or several step portions 3C to 3e and form the protrusions 3a on the surfaces of each.

The protrusions 3a of the work roll 31 may be formed not in a spiral shape as described above, but in a straight line parallel to the axis of the work roll 31.

"Effects of the Invention" According to the method for manufacturing a heat exchanger tube according to the present invention, the grooves on the surface of the metal strip formed by work rolls are gradually formed to the final shape and depth, so that Even if the material is hard and difficult to process, it is possible to easily manufacture a heat exchanger tube with an accurate shape and a groove with a high heat transfer efficiency.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an example of an apparatus for carrying out the method of the present invention, FIG. 2 is a side view with a part of the cross rolling mill in the apparatus shown in FIG. 1 in cross section, and FIG. 4(a)(b)(c)
) is a partial sectional view showing the process of forming grooves in a metal strip, and FIGS. 5(a) and 5(b) are side views showing a modified example of the work roll in a cross rolling mill. Explanation of the symbols in the main diagram: 2 is a metal strip, 21 is a groove, 3 is a cross rolling machine, 30 is a flat die, 31 is a work roll, 32 is a backup roll, 3a is a convex strip, 4 is an intermittent feed roll, 5 is a Washing tank, 6
is a winding drum, 7 is a roll cutter, 8 is a welding means, a
is a heat exchanger tube, b is a whirl roll, and Fig. 4
Figure 2

Claims (2)

[Claims] (1) While intermittently feeding a metal strip to the upper surface of the flat die of a cross rolling mill consisting of a flat die and a work roll having the structure described in the following [1] to [4], A process of gradually forming grooves of a predetermined depth on the surface of the metal strip, and rolling the metal strip in the width direction with the grooves on the inside or outside, and joining both sides to form a pipe. A method for manufacturing a heat exchanger tube, including a process. [1], The rotation axis is located at the upper part of the flat die, and the rotational axis is along the feeding direction of the metal strip, [2], A large number of protrusions are formed parallel to the circumferential surface, [3], The whirl roll is The gap between the circumferential surface of the die and the upper surface of the flat die becomes narrower toward the front in the direction of feeding out the metal strip; The metal strip rotates while moving in the width direction of the metal strip. (2) The method for manufacturing a heat exchanger tube according to claim 1, wherein the protruding stripes of the whirl roll are formed parallel or spirally to the axis of the work roll.