JPH02263513A - Manufacture of heat transfer tube having worked inside surface - Google Patents

Abstract

PURPOSE:To reduce the manufacturing cost of a heat transfer tube by inserting a rod holding a plug where grooves and projections are formed into a position where a metallic strip is formed in a tubular shape, reducing the tube diameter with a die from the outer circumference at the plug position in the tube and forming grooves and projected lines on the inside surface of the tube. CONSTITUTION:The metallic strip 1 is delivered, formed by a group of forming rolls 10-13 in a tubular shape and welded by a welding means 2 to manufacture a tube stock (a). A rod 4 is inserted from a position where the metallic strip 1 is formed in the tubular shape into the tube stock (a) to hold the plug 41. The prescribed grooves or projections are formed on the circumferential surface of the plug 41. The tube stock (a) is passed through a fixed die 31 to contract the diameter from the outer circumference or a forging die of a rotary swaging machine at the position of the plug 41 in the tube stock (a). The grooves or projected lines 6 are formed by the fixed die 31 or the forging die and the plug 41 on the inside surface of the tube stock (a). In this way, sharp grooves or projected lines can be formed on the inside surface of the tube.

Description

Detailed Description of the Invention "Industrial Application Field" The present invention relates to an improvement in the manufacturing method of heat exchanger tubes for heat exchangers such as air conditioners. The present invention relates to a method of manufacturing a heat tube.

“Prior Art” Known methods for producing this type of heat exchanger tube include a drawing method, a forging method, and a rolling method.

For example, JP-A No. 54-37059 (JP-A No. 61-598)
No. 08) Publication states that a rotatable grooved plaque connected via a shaft to a floating plaque that works together with a drawing die to shrink the raw pipe is placed at a predetermined position of the raw pipe that has passed through the drawing die. At the location where the grooved plug is located, the raw tube is pressed against the grooved plug using rolling rollers that rotate planetarily while contacting the outer circumferential surface of the raw tube to form grooves on the inner surface. A method has been proposed in which the material is finished by passing it through a finishing die.

For example, in JP-A-55-43:150, a metal strip of a constant width is continuously fed out, and the surface of the metal strip is sandwiched between a grooved roll and a rolling roll. A method is disclosed in which grooves or protrusions are formed in the metal strip, the grooves or protrusions are formed on the inner surface, the metal strip is formed into a tubular shape using a group of forming rolls, and the abutted sides are welded.

"Problem that the invention attempts to solve" Among the conventional manufacturing methods, the former method is.

The diameter of the raw pipe is reduced by drawing with a drawing die and a floating plug, and then an internal groove is formed with a grooved plug connected to the floating plug and a rolling roller, thereby significantly increasing the drawing force. However, in the case of thin-walled tubes, the tubes tend to break during machining, and it is difficult to machining deep, sharp grooves.

In addition, since there is a limit to the length of the tube that can be drawn during the tube drawing process, it is necessary to frequently supply raw tubes, and the drawing equipment must be stopped during the supply of raw tubes, which also increases manufacturing costs. do.

On the other hand, when using the latter of the conventional methods, although there is no problem as described above, the grooves or protrusions on the inner surface become discontinuous due to the beats that occur in the welded part, which tends to cause directional problems in the heat transfer performance of the heat transfer tube. , it is necessary to consider this direction when incorporating it into a heat exchanger.

In addition, when assembling a heat exchanger tube into a heat exchanger, the relevant part of the heat exchanger tube may be expanded through a hole in the tube sheet and fixed to the tube sheet, or
During this tube expansion, the beats peel off and adhere to the inside of the tube as metal powder. Furthermore, this manufacturing method has a problem in that when the grooves or protrusions are formed and then formed into a tubular shape by a group of forming rolls, the grooves or protrusions on the surface may be crushed or deformed due to the pressure of the forming rolls.

An object of the present invention is to provide a method for manufacturing an internally processed heat exchanger tube that eliminates the above-mentioned problems.

"Means for Solving the Problems" In order to achieve the above-mentioned object, the method of the present invention manufactures a blank pipe by forming a continuously fed metal strip into a tubular shape and welding the opposing sides. and a plug having a predetermined groove or protrusion formed on the circumferential surface is held in the rod which is inserted into the raw pipe from a position before the metal strip is formed into a tubular shape or a position where the metal strip is being formed into a tubular shape. , the raw tube is passed through a fixed die or a forging die of a rotary swaging machine that reduces the diameter of the portion of the raw tube at the plug position from the outer circumference without moving the raw tube in the same direction as the feeding direction of the metal strip; A step of forming grooves or protrusions on the inner surface of the raw tube using a fixed die or a forging die and the plug is adopted.

When manufacturing a metal strip into a raw pipe, if the diameter of the raw pipe is relatively large, after manufacturing the raw pipe until passing the raw pipe through the fixed die or the forging die, By passing the raw tube through a diameter reducing die or by roll forming,
The diameter is reduced until its inner diameter is approximately equal to or close to the outer diameter of the plug.

When forming spiral grooves or protrusions on the inner surface of the heat exchanger tube, the rod or plug is rotatably provided, and the grooves or protrusions are formed in the plaque in a spiral shape with respect to the axis of the plug.

``Function'' In the process of manufacturing raw pipes, by selecting metal strips with the desired wall thickness and width, the raw pipes with the desired wall thickness and diameter can be easily manufactured continuously, and the diameter of the raw pipe can be reduced. There is no need to repeat the drawing process.

In addition, the rod of the plug is inserted into the raw pipe from a position before the metal strip is formed into a tubular shape or from a portion where the metal strip is being formed into a tubular shape, so that the manufacturing process of the raw pipe and the process of inner surface processing are continuous. This eliminates the work of supplying raw pipes.

Furthermore, even if a diameter reduction process is provided between the production process of the raw pipe and the process of internal processing, in which the raw pipe is passed through a diameter reduction die, it is possible to arrange the plug lots as described above. Since the manufacturing process of the raw tube, the diameter reduction process, and the inner surface machining process are continuous, the raw tube supply work is also omitted.

In this way, by eliminating the need for repeated drawing to reduce the diameter of the raw tubes and the need for supplying the raw tubes, equipment downtime can be significantly shortened, and the heat transfer performance can be improved at extremely low costs. This makes it possible to manufacture heat exchanger tubes with internal processing properties.

Moreover, even when reducing the diameter of the raw pipe prior to internal groove machining,
Since no floating plug is used, the pulling force is reduced, and in the case of thin-walled pipes, breakage of the pipe during processing can be prevented, and deeper and sharper inner grooves can be processed.

Although one or more of the methods of the present invention are mainly described with respect to a method for manufacturing round heat exchanger tubes, the present invention may be applied to the manufacture of flat heat exchanger tubes used in automobile radiators, etc. After carrying out the method, the heat exchanger tube may be flattened using a group of shaving rolls.

"Example" Hereinafter, preferred embodiments of the method of the present invention will be explained with reference to the drawings.

From an uncoiler (not shown), a metal strip 1 made of copper, aluminum, alloys thereof, or other metals is continuously fed out at a constant speed in a constant direction as shown in FIG. 1, using appropriate means.

In this example, the metal strip l made of a copper plate with a wall thickness of 0.6 mm and a width of 60 m is fed out at a speed of 10 m/min, and is moved by six pairs of forming roll groups lO to 13.
is rolled in the width direction and gradually formed into a tubular shape, and the abutted sides are continuously welded by TIG welding, induction coil for welding, or other suitable welding means 2, and squeeze roll 14
．． 14 to continuously produce raw material tubes a having an outer diameter of 19 mm, and continuously supply the volamous tubes a to the next inner surface processing device 3.

A support arm 40 is suspended from above at a suitable position in the region where the metal strip l is being formed into a tubular shape, and a rod is inserted into the support arm 40 into the interior of the blank pipe a produced as described above. The rod 4 is provided with a spiral parallel groove on its circumferential surface so that the rod 4 is fixed and positioned within the portion of the blank tube a that reaches the inner surface processing device 3.

A plug 41 (FIG. 2) having a protrusion formed thereon is rotatably held.

Before supplying the raw pipe a to the inner surface processing device 3, as shown in FIG. 2, beats on the outer surface caused by welding are removed using a beat cutter 5, and the pipe is passed through an appropriate cooling device (not shown) to be cooled to room temperature. is desirable.

The inner surface processing device 3 is provided with a die holder 30 as shown in FIG. ), a fixed die 31 is provided to pressurize the diameter of the raw tube a toward the plug 41 side, and an appropriate pulling device (not shown) pulls the raw tube a in the same direction as the feeding direction of the metal strip l. 0.5m deep inside
By manufacturing a heat exchanger tube C having 40 spiral grooves or protrusions, and passing this heat exchanger tube C through a finishing die (not shown) provided continuously on the die holder 30, an outer diameter of 15. Finish it to 88mm and cut it to a certain length one by one.

In this embodiment, when the raw pipe a to be manufactured has a relatively large diameter, the raw pipe a is cut into a diameter reducing die (not shown) before forming grooves or protrusions on the inner surface of the raw pipe a using the inner surface processing device 3. The step of reducing the inner diameter of the blank pipe a until it becomes close to the outer diameter of the plug 41 can be adopted.

FIGS. 3 and 4 show another embodiment of the method of the present invention, and the manufacturing of the raw pipe a and the molding of the raw pipe a by the squeeze roll 21 are substantially the same as in the previous embodiment. Preferably, the welding bead is removed at the stage of the X-tube a, as in the previous embodiment, and the raw tube a is cooled to room temperature.

In addition, a rod 4 is inserted into the raw pipe a to be manufactured in the same state as in the case of the above embodiment, and the rod 4 has a spiral shape on the circumferential surface so as to be located at the part of the inner surface processing device 3. A plug 41 having grooves or protrusions formed therein is rotatably held.

The inner surface processing device 3 of this example uses a rotary swaging machine, and a diameter reducing die 6 held by a die halter 60 is provided in front of the inner surface processing device 3, and the raw pipe a is The metal strip plate 1 is moved in the same direction as the string extension direction using an appropriate l, do.

In the inner surface processing device 3, a forging die 32 of a rotary swaging machine is provided on the outer periphery of the portion of the raw pipe a where the plug 41 is located, and the outer periphery of the raw pipe a being moved is cut by the forging die 32. Pressure is applied more toward the plug 41 side, and a spiral groove or protrusion is formed on the inner surface.

That is, the forging die 32 is divided at equal angles and approaches and departs from the plug 41, and does not pressurize the raw tube a toward the plug 41 from the outer periphery. By rotating it clockwise, a heat exchanger tube C having grooves or protrusions as shown in # is manufactured while reducing the diameter of the raw tube a, and this heat exchanger tube C is passed through a finishing die (not shown). The product is obtained by sequentially cutting to a predetermined length.

In each of the above embodiments, the welding means 2 may be TIG welding, high frequency induction welding, laser welding or other known means.

Further, if the grooves or protrusions on the circumferential surface of the plug 41 are not spiral but linear parallel to the axis, the plug 41 does not need to rotate as described above, and the grooves or protrusions When forming the rod in a spiral shape, the plug 41 only needs to be rotated with respect to the blank tube a, so even if the rod 4 is rotatably held by the support arm 4G in FIG. Alternatively, the rod 4 may be fixed to the support arm 40 and the flag 41 may be rotatably held by the rod 4.

``Effects of the Invention'' The method for manufacturing an internally processed heat exchanger tube according to the present invention has the structure described in the claims, which eliminates the need for drawing in the step of manufacturing the raw tube, and the loft of the plug is adjusted to the height of the metal strip. The production of heat exchanger tubes has been improved by passing the tube from the molding part into the tube being manufactured, allowing the manufacture of the tube to continue and the inner surface processing, eliminating the need for repeated supply of the tube and shortening the downtime of the equipment. Further cost reduction can be achieved.

In addition, since the diameter is not drawn using a floating 7° lug and a drawing die, excessive drawing force is not required, there is almost no breakage of the pipe during manufacture, and deeper and sharper grooves or protrusions are created on the inner surface of the pipe. Furthermore, since the grooves or protrusions are processed after the pipe is formed, the grooves or protrusions will not be crushed or deformed.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an example of the equipment used in the manufacturing process of a blank pipe in the method of the present invention, Fig. 2 is a sectional view showing an example of the equipment used in the inner surface processing step, and Fig. 3 is a perspective view showing an example of the equipment used in the inner surface processing step. FIG. 4 is a partial vertical sectional view of the apparatus shown in FIG. Internal processing device, 31 is a fixed die, 32 is a forging die in a rotary swaging machine, 4 is a rod, 40 is a support arm, 41 is a plug, a is a raw pipe,
b indicates a groove or a ridge, and C indicates a heat exchanger tube.

Claims (3)

[Claims] (1) The step of manufacturing a raw pipe by welding the abutted sides while forming a continuously fed metal strip into a tubular shape, and the position or position of the metal strip before being formed into a tubular shape. A rod inserted into the raw tube from a position where it is being formed into a tubular shape holds a plug having a predetermined groove or protrusion on its circumferential surface, and the raw tube is moved in the same direction as the direction in which the metal strip is fed out. While moving, the part of the raw pipe at the plug position is passed through a fixed die or a forging die of a rotary swaging machine that reduces the diameter from the outer periphery, and the fixed die or forged die and the plug form a groove or groove on the inner surface of the raw pipe. A method for producing an internally processed heat exchanger tube, the method comprising the step of forming a protrusion. (2) The process of manufacturing a raw pipe by welding the abutted sides while forming a continuously fed metal strip into a tubular shape, and manufacturing the raw pipe in the same direction as the feeding direction of the metal strip. and a step of reducing the diameter of the metal strip by passing it through a diameter reducing die while moving the metal strip into a diameter reducing die, and inserting a rod into the diameter reduced blank pipe from a position before the metal band plate is formed into a tubular shape or a position where the metal band plate is being formed into a tubular shape. A plug having a predetermined groove or protrusion on the circumferential surface is held, and the diameter-reduced raw pipe is not moved in the same direction as the feeding direction of the metal strip, so that the position of the plug in the raw pipe is changed. passing the part through a fixed die or a forging die of a rotary swaging machine whose diameter is reduced from the outer periphery, and forming grooves or protrusions on the inner surface of the raw tube by the fixed die or forging die and the plug. A manufacturing method for internally processed heat exchanger tubes. (3) The internally processed heat exchanger tube according to claim 1 or 2, wherein the plug or rod is rotatable, and the groove or protrusion on the circumferential surface of the plug is formed in a spiral shape with respect to the axis of the plug. manufacturing method.