JPH10113731A - End part drawing method of flat perforated pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the unwilling deformation due to the collapse or the like of respective heat exchange medium passage holes, especially the outermost side heat exchange medium passage holes in the width direction, in the drawing process reducing the end part of a flat perforated pipe in the width direction. SOLUTION: Drawing is executed by inserting the end of the flat perforated pipe 3 into the recessed part 7 of a drawing die 6 using the drawing die 6 disposed in upright straightening pins 10 in the bottom surface of the recessed part 7 for drawing, and pins are inserted into respective heat exchange medium passage holes 5, 5a while restraining the outer periphery in the end part of the flat perforated pipe 3 with the peripheral wall of the recessed part 7 of the die 6 by further inserting the end of the pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for drawing an end of a flat porous tube used as a heat exchange tube of a heat exchanger for an air conditioner or the like.

[0002]

2. Description of the Related Art As a heat exchanger used for a condenser for a car cooler or the like, a structure in which ends of a plurality of flat porous tubes made of an extruded die material arranged in parallel are connected to a hollow header in a communicating state. A so-called multi-flow type aluminum heat exchanger is preferably used. In this heat exchanger, the flat tube and the header are inserted and fitted into the header through the tube insertion hole formed in the peripheral wall of the header in a circumferential slit shape. They are joined and integrated by brazing all together.

[0003] When inserting the tube end into the header, the length of insertion of the tube into the header is automatically set, and the dimensions of the tube width and height are corrected. As shown in FIGS. 6 (a) and 6 (b), the flat tube (51) is drawn so that its longitudinal end is reduced at least in the width direction, and the reduced end ( As shown in FIG. 6 (c), the base end step (53) of the 52) comes into contact with the peripheral edge of the tube insertion hole (55) of the header (54).

[0004]

However, in the conventional drawing, as shown in FIG. 6 (b), the heat exchange medium passage holes (56) of the flat tube (51), especially the outermost in the width direction. Heat exchange medium passage hole (56a) (56a) located at
However, it becomes narrow unintentionally due to deformation such as crushing,
Therefore, during heat exchange, the heat exchange medium passage hole (56a)
There is a problem that the flow rate of the refrigerant passing through (56a) is reduced to deteriorate the heat exchange performance or increase the refrigerant pressure loss.

The flat tube (51) and the header (5)
In the batch brazing with 4), the brazing material may flow into the narrowed heat exchange medium passage holes (56a) (56a) on both sides in the width direction and pinch the holes (56a) (56a). there were.

The present invention has been made in view of the above-mentioned conventional problems, and can prevent undesired deformation such as collapse of each heat exchange medium passage hole in end drawing of a flat porous tube. Provide an end drawing method of a flat perforated tube, thereby improving heat exchange performance, reducing pressure loss of a heat exchange medium,
It is an object to prevent hole clogging during brazing.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to provide a flat porous tube having a plurality of heat exchange medium passage holes in the width direction by drawing at least a longitudinal end portion so as to reduce at least the width direction. In a state where the outer peripheral surface of the end portion of the flat porous tube is restrained in a deformation preventing state, a pin for straightening is inserted into each heat exchange medium passage hole of the flat porous tube from the end at the same time so as to intervene in the state. The problem is solved by a method of drawing an end portion of a flat perforated pipe, wherein a step of correcting a heat exchange medium passage hole is performed.

In the above method, a drawing step of reducing in the width direction and a step of inserting a straightening pin into each heat exchange medium passage hole of the flat perforated tube from the end thereof at the same time in a state of being inserted are carried out. In addition, undesired deformation such as collapse of the heat exchange medium passage hole due to the drawing process is corrected by the intervention of the correcting pin, and each heat exchange medium passage hole is free from undesired deformation such as collapse.

Moreover, the correction with the pin interposed in the inserted state is performed while the outer peripheral surface of the end of the flat porous tube is restrained in the deformation preventing state. It is also possible to prevent the outer peripheral shape from being deviated, and to obtain a flat perforated tube whose ends are appropriately reduced in the width direction.

[0010] In addition, the above method uses a drawing die having a recess for drawing that is narrower than the flat perforated pipe and having the pin for straightening provided on the bottom surface of the recess. While drawing the end of the tube in the longitudinal direction by inserting it into the recess of the drawing die, the outer peripheral surface of the end of the flat porous tube is restrained by the peripheral wall of the recess of the die while preventing deformation. It is preferable that the pin be inserted into each of the heat exchange medium passage holes of the flat porous tube in a state of being inserted. By simply inserting the flat perforated tube into the recess of the drawing die, the end portion is appropriately reduced in the width direction, and the heat exchange medium passage holes are undesirably collapsed. An appropriate flat porous tube without any deformation is obtained, and the productivity is improved.

Further, in the flat porous tube before drawing, the cross-sectional area of the outermost heat exchange medium passage holes in the width direction is larger than the cross-sectional area of the heat exchange medium passage hole in the middle part in the width direction. It should be set. Thereby, even if the drawing process is performed to reduce the width, the outermost heat exchange medium passage hole in the width direction is not unintentionally narrowed. Therefore, it is possible to prevent an excessive mechanical load from being imposed on the pin due to the insertion of the pin for straightening, and to reduce the amount of straightening deformation of the flat porous tube by the pin, thereby obtaining a flat porous tube having good quality. .

[0012]

Next, embodiments of the present invention will be described with reference to the drawings.

The flat perforated tube according to the present embodiment is used as a heat exchange tube in a multi-flow type heat exchanger used for a condenser for a car air conditioner, for example. As shown in FIGS. 4 (a) and 4 (b), the flat porous tube (3) has a tube insertion hole (2) formed in a circumferential slit shape on the peripheral wall of a cylindrical hollow header (1) made of aluminum. Through the end,
The multi-flow type heat exchanger is inserted into the header (1) and integrally joined to the header (1) in a state of internal communication by batch brazing. The flat perforated tube (3)
The end in the longitudinal direction is reduced in the width direction by drawing, and the base end step (4) formed on both sides in the width direction of the reduced end is provided with a tube insertion hole of the header (1). The abutment is made on the periphery of (2), and the insertion amount of the end of the flat porous tube (3) is automatically set.

In the present embodiment, the end drawing of the flat porous tube (3) as described above is performed as follows.

That is, the flat porous tube before drawing is shown in FIG.
As shown in (a), an aluminum extruded material having a plurality of, for example, five heat exchange medium passage holes (5)... (5a) (5a) in the width direction has an elliptical cross-sectional outer peripheral shape. Tube. In the flat porous tube (3), the heat exchange medium passage holes (5) at the middle portion in the width direction are formed in a circular cross section and are designed to have the same size. Also,
Each heat exchange medium passage hole (5a) (5a) on the outermost side in the width direction is a passage hole (5a) after drawing in drawing described later.
The cross-sectional shape and the cross-sectional area of (5a) are designed to be the same as the cross-sectional shape and the cross-sectional area of each heat exchange medium passage hole (5). It is designed to have an elliptical or elliptical cross-sectional shape with its major axis directed in the width direction, and each cross-sectional area is larger than each of the heat exchange medium passage holes (5) at the middle part in the width direction.

Using the flat porous tube (3) having such a structure, drawing is performed so that the end is reduced in the width direction.
For this drawing, a drawing die (6) as shown in FIG. 2 is used. The mold (6) has a drawing recess (7) narrower than the flat porous tube (3). The inner side of the recess (7) except for the inlet side has an oblong shape in plan view, the length in the major axis direction is smaller than the width of the flat porous tube (3), and the length in the minor axis direction is flat. It is designed to have the same height as the perforated pipe (3). On the entrance side of the concave portion (7), both peripheral wall portions in the major diameter direction are inclined outward (9) (9).
The inclined surfaces (9) and (9) are used as aperture inclined surfaces. On the bottom surface of the concave portion (7), circular correction pins (10) for correcting the passage holes (5), (5a), (5a) of the flat porous tube (3) are provided upright. The height of each straightening pin (10) is the upper end of the slope (9).
It is set to be located lower than (9). The cross-sectional shapes and sizes of the correction pins (10) are designed to be the same.

The drawing process of the end of the flat porous tube (3) is performed as follows using this mold (6). That is, as shown in FIG. 1 (a), the longitudinal end of the flat porous tube (3) is inserted into the recess (7) of the mold (6). Then, as shown in FIG. 1 (b), the ends of the flat perforated pipe (3) extend from the front end to both sides in the width direction.
The drawing is reduced in the width direction by the drawing inclined surfaces (9) and (9) on the entrance side of the mold concave portion (7) and drawing is performed. By this drawing, each of the heat exchange medium passage holes (5)... (5a) (5) inside the flat perforated pipe (3) at the drawn part.
a) is deformed. In particular, a relatively large deformation occurs in the heat exchange medium passage holes (5a) (5a) on the outermost side in the width direction, and the passage area is reduced and deformed. Therefore, the flat perforated tube (3)
Is inserted further inward, and as shown in FIG. 1 (c), the insertion pins (10)...
(5) ... (5a) and (5a).
By inserting these pins (10), the heat exchange medium passage holes (5), (5a), (5a) are corrected into holes having appropriate shapes. In particular, the outermost heat exchange medium passage holes (5a) (5
a) is corrected into a hole having an appropriate shape by inserting the pins (10).

As described above, as shown in FIG. 3B, the end is reduced in the width direction, and the heat exchange medium passage holes (5)... (5a) (5a) at the end are formed. A flat perforated pipe (3) having a circular cross section and an equal cross-sectional area is obtained.

As described above, in the above-described embodiment, after performing the drawing process in which the width direction is reduced at the end of the flat porous tube (3), each heat exchange medium passage hole of the flat porous tube (3). (5) ... (5a) At (5a), insert a pin (1
0) are inserted at the same time, so the heat exchange medium passage holes (5) ... (5a) formed by drawing in the width direction are reduced.
(5a) can correct undesired deformation such as crushing,
Each heat exchange medium passage hole (5) ... (5a) (5a) is free from unintentional deformation such as crushing, so that heat exchange performance is improved, pressure loss of the heat exchange medium is reduced, and holes for brazing. Prevention of jamming can be realized.

Further, the pins (10) are inserted while the outer peripheral surface of the end of the flat porous tube (3) is restrained by the inner peripheral wall of the concave portion (7) of the mold (6) in a deformation preventing state. It is possible to prevent the end outer peripheral shape of the flat perforated tube (3) from being distorted due to the insertion of the pin (10). The flat perforated tube whose end is appropriately reduced in the width direction. A tube (3) can be obtained.

In particular, since the drawing die (6) in which straightening pins (10)... Are provided on the bottom surface of the drawing recess (7) is used, the flat porous tube (3) is drawn. By simply performing the operation of being inserted into the concave portion (7) of the processing die (6), the end portion is appropriately reduced in the width direction, and each heat exchange medium passage hole is undesirably deformed such as collapsed. An appropriate flat perforated pipe (3) free of defects can be obtained, and processing can be performed with high productivity.

Further, the flat porous tube (3) before drawing is
The cross-sectional area of each of the outermost heat exchange medium passage holes (5a) (5a) in the width direction is set to the heat exchange medium passage hole (5)
Are set to be larger than the cross-sectional area of..., The outermost heat exchange medium passage holes (5a) (5a) in the width direction are undesirably narrowed even if the drawing process is performed in the width direction. Therefore, it is possible to prevent an excessive mechanical load from being applied to the pin (10) when inserting the pin for correction, and to correct the deformation of the flat porous tube by the pin (10). And a flat perforated tube of good quality can be obtained. Moreover, the cross-sectional area and cross-sectional shape of each heat exchange medium passage hole (5)... (5a) (5a) at the end of the flat porous tube (3) can be made the same, and each heat exchange medium passage hole (5 5)
(5a) The flow rate of the heat exchange medium passing through (5a) can be equalized.

Since the pin (10) is inserted into all the passage holes (5)... (5a) (5a), the insertion of the pin (10) into one passage hole (5a) is performed. It is possible to prevent the occurrence of a secondary inconvenience such as the deformation of the other passage hole (5) due to the correction and the narrowing of the passage hole (5).

In the embodiment shown in FIGS. 1 to 4, after the flat perforated pipe (3) is first drawn, the pins are inserted into the heat exchange medium passage holes (5)... (5a) (5a). As described above, the height of the straightening pin (10) is increased, and the pin (10) is inserted into the heat exchange medium passage holes (5)... (5a) (5a) before drawing. Is also good. In addition, although it has been described that the hole correction is performed after the drawing, the drawing and the hole correction may be performed simultaneously.

FIG. 5 shows another embodiment method. In this method, first, as shown in FIGS. 5A and 5B, the end of the flat perforated tube 3 is drawn using a mold 11 provided with no insertion pin. Fig. 5
(C) As shown in (d), the end of the drawn flat perforated pipe (3) is inserted into a mold (6) provided with insertion pins (10). Insert the pins (10) into the heat exchange medium passage holes (5) (5a) (5a). As described above, the drawing process and the straightening process using the pin may be performed as separate processes using different molds (11) and (6).

Although the embodiment of the present invention has been described above, the present invention is not limited to this, and various modifications are possible. For example, in the above embodiment, the cross-sectional area of the outermost heat exchange medium passage holes (5a) (5a) in the widthwise outermost portion of the flat porous tube (3) to be drawn is the heat exchange medium in the middle part in the widthwise direction. Designed to be larger than the cross-sectional area of the passage holes (5), but all the heat exchange medium passage holes (5) ... (5a)
(5a) may be designed to be the same size. In that case, the outermost heat exchange medium passage holes (5a) (5a) that have been crushed by the drawing process are expanded and corrected by the outermost insertion pins (10) (10). In the above embodiment, a flat porous tube made of an extruded material is used, but the invention is not limited to the extruded material. Further, in the above embodiment, the case where the end of the flat porous tube (3) is drawn only in the width direction is described, but the drawing may be performed in both the width direction and the height direction. .

[0027]

As described above, according to the method for drawing an end of a flat perforated pipe of the present invention, the end of the flat perforated pipe having a plurality of heat exchange medium passage holes in the width direction is formed at least in the width direction. Drawing step so as to reduce the size of the heat exchange medium passage hole, and inserting the straightening pin into each heat exchange medium passage hole of the flat perforated tube at the same time from the end of the heat exchange medium passage hole so as to interpose the heat exchange medium passage hole. Because it implements
Undesired deformation such as collapse of the heat exchange medium passage hole due to the drawing process in the width direction is corrected by the intervention of the correcting pin, so that each heat exchange medium passage hole is free from undesired deformation such as collapse. It is possible to improve the heat exchange performance, reduce the pressure loss of the heat exchange medium, and prevent clogging of holes at the time of brazing.

Further, since the heat exchange medium passage hole is corrected by inserting the pin in the inserted state, the end outer peripheral surface of the flat porous tube is restrained in the deformation preventing state. In addition, it is possible to prevent the outer peripheral shape of the flat porous tube from being out of order, and to obtain a flat porous tube whose end portion is appropriately reduced in the width direction.

Further, the above-mentioned method uses a drawing die having a drawing recess having a width narrower than that of the flat perforated tube and having the above-mentioned pin for correction standing upright on the bottom surface of the recess. While drawing the end of the tube in the longitudinal direction by inserting it into the recess of the drawing die, the outer peripheral surface of the end of the flat porous tube is restrained by the peripheral wall of the recess of the die while preventing deformation. By inserting the pin into each heat exchange medium passage hole of the flat perforated tube in the inserted state,
By simply inserting the flat perforated tube into the recess of the drawing die, the end portion is properly reduced in the width direction, and each heat exchange medium passage hole is undesirably deformed such as collapsed. An appropriate flat perforated pipe can be obtained, and the processing can be performed with high productivity.

Further, in the flat porous tube before drawing, the cross-sectional area of the outermost heat exchange medium passage holes in the width direction is larger than the cross-sectional area of the heat exchange medium passage hole in the widthwise middle part. By setting it, even when drawing in the width direction is reduced, the heat exchange medium passage hole on the outermost side in the width direction is not unintentionally narrowed. It is possible to prevent an excessive mechanical load from being applied to the pin due to the insertion, and to reduce the amount of correction deformation of the flat porous tube by the pin, thereby obtaining a flat porous tube having good quality.

[Brief description of the drawings]

FIGS. 1A to 1C are cross-sectional views sequentially illustrating a procedure of a method according to an embodiment.

FIG. 2 is a sectional view showing a drawing die.

FIGS. 3A and 3B show a drawn flat perforated tube, in which FIG. 1A is a plan view, FIG. 2B is a view taken along line II of FIG. 1A, and FIG. 2) is a sectional view taken along line II-II.

FIGS. 4A and 4B show a heat exchanger incorporating a flat perforated tube having an end drawn, wherein FIG. 4A is a plan sectional view and FIG. 4B is a front sectional view.

5A to 5D are cross-sectional views sequentially showing the procedure of a method according to another embodiment.

6 (a) is a plan view of a flat porous tube, an end view thereof, and FIG. 6 (b) is a plan view, an end view, and FIG. It is a plane sectional view of a heat exchanger in the state where a flat perforated tube was inserted in a tube insertion hole of a hollow header.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 3 ... Flat porous tube 5, 5a ... Heat exchange medium passage hole 6 ... Drawing die 7 ... Drawing concave part 10 ... Insertion pin

Claims (3)

[Claims] 1. A step of drawing a longitudinal end portion of a flat porous tube having a plurality of heat exchange medium passage holes in a width direction so as to reduce at least the width direction, and an outer periphery of the end portion of the flat porous tube. The heat exchange medium passage hole is straightened by simultaneously inserting a straightening pin into each heat exchange medium passage hole of the flat porous tube from its end in a state where the surface is restrained in the deformation preventing state. A method for drawing an end of a flat perforated pipe, comprising performing a step. 2. A longitudinal drawing of a flat perforated pipe having a concavity for drawing which is narrower than the flat perforated pipe, and a drawing die in which the pin for straightening is provided on a bottom surface of the concave. Direction by inserting the end in the direction into the concave portion of the drawing die, while restricting the outer peripheral surface of the end of the flat porous tube to the peripheral wall of the concave portion of the die while preventing the flat porous tube from deforming. The end drawing method for a flat perforated pipe according to claim 1, wherein the pin is inserted into each heat exchange medium passage hole of the pipe in a state of being inserted. 3. The flat porous tube before drawing has a cross-sectional area of the outermost heat exchange medium passage holes in the width direction which is larger than a cross-sectional area of the heat exchange medium passage holes in the widthwise middle part. The end drawing method for a flat perforated pipe according to claim 1 or 2, wherein: