JPH02263514A - Manufacture of flat heat transfer tube having inside groove - Google Patents

Abstract

PURPOSE:To manufacture a flat heat transfer tube excellent in efficiency of heat transfer 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 form rolling tool making planetary revolution from the outer circumference at the plug position in the tube, working grooves on the inside surface of the tube and flattening 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 being formed in the tubular shape into the tube stock (a) so that the rod holds the plug 41. The prescribed grooves or projections are formed on the circumferential surface of the plug 41. The tube stock (a) is pressed by the form rolling tool 3 making planetary revolution from the outer circumference to the plug 41 and while the tube stock (a) is reduced in its diameter, grooves (b) are worked on the inside surface. The tube stock (a) is formed flat. In this way, the flat tube having inside grooves can be manufactured.

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention relates to a method for manufacturing flat heat exchanger tubes with internal grooves used, for example, in automobile radiators. The present invention relates to a method for manufacturing a new flat heat exchanger tube with internal grooves.

"Prior Art" Conventionally, flat heat exchanger tubes used in automobile radiators, etc. are made by forming smooth-surfaced metal strips of copper, copper alloy, aluminum, aluminum alloy, etc. into a cylindrical shape by roll forming or drawing. Both sides of the tube are welded using high-frequency induction welding, etc. to produce a blank tube, and after the welding beats of this tube are removed (only on the outer surface), the tube is manufactured by roll forming or drawing into a flat shape. No manufacturing method has yet been proposed that involves machining grooves.

Some home air conditioning heat exchangers use round tubes with grooves on their inner surfaces. There was a legal method.

One method is to manufacture a pipe of a predetermined size by cold drawing a hot extruded raw pipe several times, and use this raw pipe as, for example,
The inner surface is grooved by the method disclosed in Japanese Patent Publication No. 37059 (Japanese Patent Publication No. 61-59808). That is, in this method, a rotatable grooved plug connected via a shaft to a floating plug 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. After holding the raw pipe and pressing it against the grooved plug with a rolling roller that rotates planetarily while contacting the outer circumferential surface of the raw pipe in the region where the grooved plug is located, grooves are formed on the inner surface of the pipe. The material is finished by passing it through a finishing die.

The other method is to form a pipe by electric resistance welding a rolled metal strip of a predetermined size. While continuously feeding out, the metal strip is sandwiched between a groove processing goal and a rolling roll to form grooves or protrusions on the surface of the metal strip, and the metal strip is formed with the grooves or protrusions forming the inner surface. It is formed into a tubular shape using a group of rolls, and both sides of the butt are welded.

``Problem to be solved by the invention'' Recently, due to the demand for thinner, lighter, and smaller tubes in heat exchangers such as automobile radiators, the flat heat exchanger tubes used are, for example, thinner than conventional ones. There is a demand for flat tubes with thin walls and small diameters such as 0.35mm and 0.35m+i, which used to be 0.40mm, but the conventional flat heat exchanger tubes mentioned above have smooth inner surfaces and have no grooves or protrusions, so As the thickness of the heat exchanger became thinner, it was impossible to improve the heat transfer efficiency, and there was a limit to the miniaturization of the heat exchanger.

For the purpose of improving heat transfer efficiency, let's manufacture a flat heat transfer tube with a thin wall and internal grooves by the method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 54-37059 (Japanese Patent Publication No. 61-59808). In this case, this method involves reducing the diameter of the raw pipe by drawing with a drawing die and a floating plug, and subsequently forming internal grooves with a grooved plug connected to the floating plug and a rolling roller. Therefore, the drawing force increases significantly, making the thin-walled tube easy to break during machining, and furthermore, it is difficult to machining a deep, sharp groove shape, making it difficult to say that it is appropriate.

Furthermore, as mentioned above, after a large-diameter, thick-walled pipe is made into a small-diameter, thin-walled pipe by multiple drawings using the conventional drawing method, groove processing must be performed using the method described above, which increases the manufacturing cost of the stock pipe. There is a problem of increasing

On the other hand, the above-mentioned Japanese Patent Application Laid-Open No. 55-4 discloses an electric resistance welded pipe made from a metal strip.
When adopting the method disclosed in Publication No. 3360, there are no problems such as breakage as shown in #, and there are no manufacturing cost problems due to repeated drawing, but the beats that occur in the welded part may cause grooves and cracks on the inner surface. The protrusions become discontinuous, which tends to cause directional properties in the heat transfer performance of the heat transfer tube, and this directional property must be taken into consideration when incorporating it into a heat exchanger such as a radiator.

Furthermore, this manufacturing method has a problem that, after the grooves or protrusions are formed, when they are 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 on the side of the grooves or protrusions. There is.

An object of the present invention is to provide a method of manufacturing a flat heat exchanger tube with good heat transfer efficiency by forming grooves on the inner surface of a flat heat exchanger tube such as a radiator of an automobile, and another object of the present invention is to
It is an object of the present invention to provide a method for manufacturing a flat heat exchanger tube with internal grooves that can be easily manufactured and eliminates the above-mentioned manufacturing problems.

``Means for Solving the Problems'' In order to achieve the above-mentioned object, the first method of the present invention is to form a continuously fed metal strip into a tubular shape, and then weld the opposing sides to form a blank. A step of manufacturing a tube, and moving the raw tube in the same direction as the feeding direction of the metal strip 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. A rotatable grooved plug provided on a rod that plunges into the raw pipe, and a rolling tool (for example, a roller or ball) that rotates planetarily around the outer periphery of the raw pipe while pressing the raw pipe from the outer periphery to the plug. , a step of forming grooves on the inner surface of the tube while reducing the diameter of the tube, and a step of forming the tube into a flat shape.

The second aspect of the method of the present invention is the step of manufacturing a blank pipe by welding the abutted sides while forming a continuously fed metal strip into a tubular shape, and the process of producing a blank pipe by welding the metal strips that are continuously fed out into a tubular shape. A step of reducing the diameter from the tip without moving the metal strip in the same direction as the metal strip, and a step of reducing the diameter of the metal strip from a position before it is formed into a tubular shape, or a positional force when the metal strip is being formed into a tubular shape. A step of forming grooves on the inner surface of the raw pipe using a freely rotatable grooved plug and a rolling tool that rotates planetarily around the outer periphery of the raw pipe while pressing the raw pipe from the outer periphery to the plug. It is something.

"Examples and Effects" Examples of the method of the present invention will be described below along with their effects.

As shown in FIG. 1, the metal strip 1 is fed out in a constant direction at a constant speed by an appropriate means from an uncoiler (not shown).

In this example, the metal strip l has a width of 31 mm and a wall thickness of 0.
．． 40mm aluminum alloy laminated board (core material JIS30
0, skin material on the outside surface of the tube: Brazing material JIS4
045 (coverage rate 8.3%), skin material for the inner surface of the tube: sacrificial material JIS7072 (coverage rate 10.2!)
), and while feeding it out at a speed of 100/min, the metal strip l is gradually rolled into a tubular shape in the width direction by six pairs of forming and forming rolls lO~13, and then punched. The joined sides were continuously welded using a welding induction coil (TIG welding or other suitable welding means may be used) 2, and pressed and shaped using squeeze rolls 14 and 14 to form an outer diameter of 9.5 m.
m blank tubes a were continuously manufactured, and the blank tubes a were continuously supplied to the next groove processing device 30.

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 the rod 4 is inserted into the support arm 40 into the blank pipe a produced as described above. At the same time, the groove machining device 3 for the raw pipe a is fixed.
A grooved plug 41 (FIG. 2) having parallel spiral grooves formed on the circumferential surface of the rod 4 is rotatably held at the tip of the rod 4 so as to be located within the portion where the rod 4 reaches zero.

With this configuration, the manufacturing process of the welded pipe and the processing process for forming internal grooves are continuous, and it is possible to form more uniform and sharp internal grooves while preventing pipe breakage. There is.

Before supplying the raw pipe a to the groove processing equipment @30, the beats on the outer surface caused by welding are removed using a beat cutter 5 as shown in Fig. 2, and the pipe is cooled to room temperature by passing it through a suitable cooling device 6. desirable.

In the groove machining device 30, as shown in FIG. 2 (an embodiment corresponding to the second method of the present invention), a hollow drawing die 7 is held in a die holder 70 fixed to the front surface of the housing 31.
The raw pipe a is moved in the same direction as the feeding direction of the metal band plate 1 (
While being pulled out (from the right side to the left in FIG. 2), the plug is passed through the empty drawing die 7, and the inside diameter is reduced to a state where the inside diameter is approximately equal to or close to the outside diameter of the plug 41.

A spindle 33 is rotatably provided in the housing 31 via a bearing 32 at a position subsequent to the diameter reducing die 7 of the groove processing device N30, and a roller holder 34 is attached to the tip of the spindle 33. 34, insert the raw pipe a into the inner plug 4 from the outer periphery.
A rolling tool 3 consisting of a plurality of rollers is provided at equal angular intervals, and a spindle 33 is rotated at high speed via a belt 35 by a drive device (not shown), and the rolling tool 3 is rotated at a revolution number of 24,000 rpm. Move the raw tube a to the left in FIG.
．． A spiral groove with a depth of 0° and 15 mm was formed.

Next, without moving the base pipe a with the groove formed, the third
As shown in the figure, it is formed into a flat shape by six pairs of shaving roller groups 80 to 82, and as shown in FIGS. 3 and 4, it has a spiral groove with a depth d or 0.15 mm on the inner surface, The wall thickness at the bottom of the groove is 0.325 mm, and the short outer diameter is 2.20 m.
A flat heat exchanger tube C having a long outer diameter of 14 mm was manufactured.

The welding bead on the outer surface of the flat heat exchanger tube C is removed by the beat cutter 5, and the inner bead is also small due to high frequency induction welding and is crushed during groove processing, so there will be no problem when used in a heat exchanger. In addition, the strength of the area near the weld, which has deteriorated due to the thermal effect during welding, is improved by work hardening due to the suppression during groove processing.

The amount of diameter reduction due to empty drawing should not be too large in order to reduce die wear and to reduce the pulling force required for empty drawing. In addition to the above-mentioned dry drawing, the diameter can also be reduced by roller molding, and in this case too, the amount of diameter reduction should not be excessive.

The above explanation relates to an embodiment corresponding to the second method of the present invention, but when carrying out the first method of the present invention, the apparatus without the empty drawing die 7 shown in FIG. 2 is used. After producing the raw tube a as described above, the inner surface grooves are processed without passing the raw tube a through an air drawing die. This method is carried out when the manufactured raw tube a has good dimensional accuracy and the inner diameter of the raw tube a is approximately equal to the outer diameter of the grooved plug 41.

In carrying out the first method of the present invention, for example, to prevent the torsional force on the raw pipe a caused by the revolution of the rolling tool 3 from acting on the welded part of the raw pipe a and causing defects, for example, By means such as holding the raw tube a with rolls to prevent rotation,
It is desirable to prevent adverse effects on the welding area.

It is preferable that the blank tube a is pulled out using, for example, a rubber caterpillar drive device (not shown), and the forming roll group is driven in the pulling direction to reduce the pulling force, and the pulling speed and welding speed are controlled to be synchronized. It is desirable to prevent the thin-walled tube from breaking.

In the third embodiment, the rolling tool 3 has a grooved plug 41 as shown in FIG. 5 instead of the roller shown in FIG.
You can use a ball that revolves around a planet.

In FIG. 5, 36 is a ball holder, and the other structure of the groove machining device 30 is the same as that in FIG. 2.

In each of the above embodiments, the welding means 2 is high frequency induction welding,
TIG welding or other known welding means can be used, or high frequency induction welding with fewer weld beats is preferable.

Also, the groove on the circumferential surface of the plug 41! The plug 41 rotates as the inner grooved tube travels, but since the plug 41 rotates with respect to the raw tube a, it attaches to the support arm 40 in FIG. The rod 4 may be fixed to the support arm 40 and the plug 41 may be rotatably held to the rod 4. ``Effects of the Invention'' According to the present invention According to the manufacturing method of flat heat exchanger tubes, the inner surface is grooved, so it is possible to manufacture flat heat exchanger tubes with good heat transfer efficiency, and it is possible to make the tubes more compact and to make the entire heat exchanger smaller. can.

In addition, since the method of the present invention allows the use of thinly rolled metal strips from the beginning, there is no need for multiple drawings to reduce the diameter of the pipe as in the conventional method. By inserting the material into the tube from the position before it is formed into a tube shape or from the position where it is being formed into a tube shape, the manufacturing process of the mother tube and the process of internal processing can be carried out continuously, which makes it possible to manufacture flat surfaces with internal grooves at a lower cost. Can manufacture heat exchanger tubes.

In addition, since the grooves are processed after forming the metal strip into a tube shape and manufacturing the raw tube, the grooves on the inner surface are continuous, so there is no directionality in heat transfer performance and the grooves do not collapse. .

Moreover, even when reducing the diameter of the raw pipe prior to internal groove machining,
(no floating plug) reduces the pulling force, prevents pipe breakage during groove processing, especially in the case of thin-walled pipes, and creates deeper and sharper grooves.

It is possible to perform internal groove machining.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an example of the equipment used in the manufacturing process of the raw pipe according to the method of the present invention, Fig. 2 is a cross-sectional view showing an example of the equipment used in the process of forming grooves on the inner surface, and Fig. 3 is a perspective view showing an example of the equipment used in the process of forming the pipe into a flat shape. A perspective view illustrating the process, FIG. 4 is a partially enlarged sectional view of the flat heat exchanger tube manufactured in the embodiment shown in FIGS. 1 to 3, and FIG. 5 is a portion showing another example of the apparatus in the groove processing process. FIG. Explanation of the symbols in the main figures ■ is a metal strip, lO~13 is a group of forming rolls, 2 is a welding means, 3 is a rolling tool, 30 is a groove processing device, 31 is a housing, 33 is a spindle, 34 is a roller holder 4 is a rod, 40 is a support arm, 41 is a grooved plug, 5 is a beat cutter, and 7 is a blank die. a is a raw tube, b is a groove, and C is a flat 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 manufacturing the raw pipe in the same direction as the feeding direction of the metal strip. A rotatable grooved plug provided on a rod that protrudes 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 while moving the raw pipe to A step of forming grooves on the inner surface of the raw tube while reducing the diameter of the raw tube using a rolling tool that planetarily rotates the outer periphery of the raw tube while pressing the plug from the outer periphery, and shaping the raw tube into a flat shape. A method for manufacturing a flat heat exchanger tube with internal grooves, the method comprising: (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 rotatable grooved plug provided on the rod that protrudes 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. , forming grooves on the inner surface of the raw pipe using a rolling tool that planetarily rotates the outer periphery of the raw pipe while pressing the raw pipe from the outer periphery to the plug; and forming the raw pipe into a flat shape. A method for manufacturing a flat heat exchanger tube with internal grooves, the method comprising: (3) The method for manufacturing an internally grooved flat heat exchanger tube according to claim 1 or 2, wherein the groove of the grooved plug has a spiral shape with respect to the axis of the plug.