JP2001071024A - Production of inner face grooved tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inner face grooved tube production method having a high working precision and high productivity. SOLUTION: A mandrel 5 consisting of a connection bar 4, in which a grooved plug 2 is joined to its tip and a floating plug 3 is connected to a rear end, is inserted into a metal tube 1 to work the inner face and is passed through the metal tube 1 while pressing with plural pressing means 20, 21 arranged in the axial direction of the grooved plug 2, a prescribed indentation is obtained as a whole, a working precision is improved. By increasing a number of pressing means 20, 21, a number of rotation (m) (rotation number of pressing means/ drawing speed) is lowered. As a result, when a drawing speed of the metal tube 1 is increased, the number of rotations of the pressing means 20, 21 is not increased, thus, the drawing speed can be increased, further, the productivity is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for manufacturing an internally grooved tube.

[0002]

2. Description of the Related Art Heat exchangers such as air conditioners and refrigerators include:
2. Description of the Related Art A heat transfer tube has been used in which a phase-change refrigerant flows in a tube and exchanges heat with a fluid outside the tube to cause evaporation or condensation of the refrigerant.

[0003] As a heat transfer tube, for example, in a heat exchanger such as a room air conditioner, an inner surface groove provided with a spiral continuous groove on an inner surface thereof in order to promote heat conduction by evaporation and condensation of a refrigerant in the tube. A heat transfer tube is used. There are a seamless type and a seam type for the inner grooved pipe. As a seamless type manufacturing method, for example, Japanese Unexamined Patent Publication No.
No. 7059, Japanese Patent Laid-Open No. 6-15345, Japanese Patent No. 2756192, and the like.

FIG. 4 is an explanatory view for explaining a conventional method of manufacturing a tube with an inner groove.

A grooved plug 2 is connected to the tip of a metal tube 1 to be machined, and a floating plug 3 is
Insert the mandrel 5 consisting of the connecting rod 4 to which is connected,
The metal tube 1 into which the mandrel 5 is inserted is inserted into the drawing die 6 so that the floating plug 3 remains at the position of the drawing die 6, and at the position of the grooved plug 2 on the outlet side (the right side in the figure) of the drawing die 6. By pressing the outer circumference of the metal tube 1 through the metal tube 1 while pressing it with the planetary rotating roll 7 of the pressing means 8, the inner surface grooved tube 9 in which the inner surface of the metal tube 1 is continuously grooved is formed. Is obtained. Further, emptying is performed by a drawing die 10 arranged at the subsequent stage (right side in the figure) of the pressing means 8 to finish to a predetermined outer diameter.

Here, the pressing means 8 includes a plurality of rolls 7.
And a support member 11 that supports the roll 7 so as to be positioned on the outer periphery of the metal tube 1, and a rotation mechanism 12 that drives the support member 11 to rotate around the outer periphery of the metal tube 1.

In the case of a grooved plug, the fin-forming groove formed on the outer periphery thereof has a different angle from the axis.

[0008]

However, in recent years,
From the viewpoint of improving heat transfer, the height of the fin is increased to form the groove, and the fin apex angle formed by both side surfaces of the fin is reduced. As a result, the shape of the fin formed by the groove portion of the grooved plug inserted into the metal pipe is deteriorated, and the workability is reduced. Therefore, in order to obtain a predetermined fin height, it is necessary to reduce the pitch in the tube axis direction pressed by the pressing means.

Here, if the value obtained by dividing the number of rotations of the roller of the pressing means by the metal tube drawing speed is m, the pitch in the tube axis direction pressed by the pressing means becomes smaller.
This means that the number of rotations increases. This means that when the number of rotations of the roller of the pressing means is the same, the speed at which the metal tube is pulled out becomes slow, leading to a decrease in productivity. In addition, when the drawing speed is increased, the rotation speed becomes higher, and there is a problem that a jig is deformed by a centrifugal force generated by the pressing means and the like, so that it cannot be processed to a predetermined size. For this reason, there has been a problem that the drawing speed cannot be increased and productivity is reduced.

Further, if the number of rollers incorporated in one set of pressing means is increased, the number of rotations of the pressing means can be reduced. However, as the pipe diameter becomes smaller, the diameter of a roll or a ball used as the pressing means becomes smaller. When the roll diameter is small and the pressing amount is the same as when the ball diameter is large, there is a problem that the metal tube expands on the inlet side of the pressing means, and a processing trouble such as disconnection occurs.

It is an object of the present invention to solve the above-mentioned problems and to provide a method of manufacturing an inner grooved pipe having high processing accuracy and high productivity.

[0012]

In order to achieve the above object, a method of manufacturing an inner grooved pipe according to the present invention is characterized in that a grooved plug is connected to a tip of a metal pipe to be machined, and a floating plug is connected to a rear end. Insert the mandrel consisting of the connected connecting rods, insert the metal tube into the drawing die so that the floating plug stays at the position of the drawing die, and connect the metal tube from the outside at the position of the grooved plug on the outlet side of the drawing die. In a method for manufacturing an inner grooved tube in which a plurality of grooves are formed on an inner surface of a metal tube by passing while pressing by a pressing means, a plurality of grooves are formed in an axial direction of the metal tube at positions where grooved plugs of the metal tube are inserted. The pressing means is disposed, and each pressing means presses the metal tube.

In addition to the above configuration, the pressing means used in the method for manufacturing an inner grooved tube of the present invention includes a ball disposed on the outer periphery of the metal tube, a support member for supporting the ball, and a support member provided on the outer periphery of the metal tube. When the pushing amount Pr is defined as 1/2 of the difference between the outer diameters of the metal pipes before and after the pressing means, a ratio P between the pushing amount Pr and the ball diameter Db of the pressing means is provided.
r / Db may be set to 0.015 or less.

In addition to the above configuration, the pressing means used in the method for manufacturing an inner grooved tube of the present invention includes a roll disposed on the outer periphery of the metal tube, a support member for supporting the roll, and a support member provided on the outer periphery of the metal tube. When the pushing amount Pr is defined as 1/2 of the difference between the outer diameters of the metal pipes before and after the pressing means, a ratio P between the pushing amount Pr and the ball diameter Db of the pressing means is provided.
r / Db may be set to 0.015 or less.

[0015] In addition to the above structure, after the inner surface of the metal tube is grooved by the pressing means used in the method for manufacturing an inner surface grooved tube of the present invention, the metal tube is emptied with a plurality of dies. It is preferable to finish to a predetermined outer diameter.

In addition to the above configuration, the method of manufacturing an inner surface grooved tube according to the present invention provides a method of manufacturing a metal tube by using a mandrel having a protruding plug having a protrusion formed in a direction opposite to a groove of a grooved plug connected to a tip as a mandrel. Notched fins may be formed on the inner surface.

According to the present invention, a mandrel composed of a connecting rod having a grooved plug connected to the front end and a floating plug connected to the rear end is inserted into the metal tube, and the plurality of mandrels arranged in the axial direction of the grooved plug are inserted. By passing through the metal tube while gradually pressing the pressing means, a predetermined pressing amount is secured as a whole, and the processing accuracy is improved. Also, by increasing the number of pressing means, the number of m rotations (the number of rotations of the pressing means /
(Drawing speed). As a result, even if the drawing speed of the metal tube is increased, the rotation speed of the pressing means does not increase, so that the drawing speed can be increased and the productivity is improved.

Here, the material of the metal tube pressed by the pressing means flows into the groove portion of the groove plug immediately below the pressing means to form fins on the inner surface of the metal tube, whereby the grooved pipe is processed. You. However, between the grooves of the grooved plug, the material of the metal tube pushed by the pressing means must move in the axial direction and the circumferential direction of the metal tube.
If the amount of movement of the material of the metal tube is substantially the same as the amount of the material of the metal tube entering the groove of the groove plug, the circumferential extension of the metal tube becomes small.

However, when the pushing amount increases, the amount of material of the metal tube processed between the grooves of the grooved plug increases, and the elongation in the metal tube axial direction and the metal tube circumferential direction increases. . As a result, when the circumference of the metal tube increases, phenomena such as displacement of the fins in the axial direction and expansion of the metal tube at the entrance of the pressing means occur, making processing difficult.

In particular, the expansion of the metal tube at the entrance of the pressing means is likely to occur when the ball diameter (or roller diameter) is small and the pushing amount is large. Taking the ratio of the indentation amount and the ball diameter (indentation amount / ball diameter) and looking at workability, if the indentation amount / ball diameter is 0.015 or more, the metal tube expands at the entrance of the pressing means. When the ratio is 0.015 or less, the metal tube does not expand at the pressing means entrance.

Therefore, the ratio Pr / Db of the pushing amount Pr to the ball diameter (roll diameter) Db of the pressing means is 0.015.
It is preferable to make the following.

[0022]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is an explanatory view for explaining an embodiment of a method for manufacturing an inner grooved pipe according to the present invention. Note that common members are used for members similar to those shown in FIG.

A mandrel 5 composed of a connecting rod 4 having a grooved plug 2 connected to the front end and a floating plug 3 connected to the rear end is inserted into the metal tube 1 to be processed, and the mandrel 5 is inserted. The metal tube 1 is inserted into the drawing die 6 so that the floating plug 3 remains at the position of the drawing die 6, and two stages (two stages in the figure, but three or more stages) at the position where the grooved plug 2 is inserted. The metal tube 1 is passed (pulled out) while being pressed from the outside of the metal tube 1 by the pressing means 20 and 21), whereby the inner surface of the metal tube 1 is continuously grooved, and the fins are formed. Is obtained.

Here, the pressing means comprises a plurality of balls (or rolls) arranged on the outer periphery of the metal tube 1, a support member for supporting the balls (or rolls), and a rotation of the support member in the circumferential direction of the metal tube. A ball (or a roll) rotates in a planetary manner around the outer circumference of the metal tube 1 with a rotating mechanism to be rotated. Two sets (three or more sets) of the pressing means are arranged in the axial direction of the metal tube at positions where the grooved plugs of the metal tube are inserted. Further, pressing means 20, 2
1, a drawing die 10 disposed at the subsequent stage (right side in the figure).
A blanking is performed by a and 10b to finish to a predetermined outer diameter. The number of drawing dies 10a and 10b is two in the figure, but is not limited.

The outer diameter of the floating plug 3 of the mandrel 5 may be slightly larger than the inner diameter of the drawing die 6 and large enough to allow a metal pipe to be internally processed to pass through.

FIG. 2 is an enlarged view of the pressing means shown in FIG.

The pressing means comprises a first pressing means 20 and a second pressing means 21.

The pressing means 20 includes a plurality of balls 22, rings 23 and 24 for supporting the balls 22 on the outer periphery of the metal tube 1, a retainer 25 for holding the balls 22 in the rings 23 and 24, 26, and a rotation mechanism (not shown) for rotating the rings 23 and 24.

Similarly to the pressing means 20, the pressing means 21 includes a plurality of balls 27, rings 28 and 29 for supporting the balls 27 on the outer periphery of the metal tube 1, and rings 28, 29.
It comprises retainers 30 and 31 for holding the ball 27 in 29 and a rotating mechanism (not shown) for rotating the rings 28 and 29.

Conventionally, the fins were completely formed on the inner surface of the metal tube by one set of pressing means. In the present embodiment, however, the first pressing means 20 uses the conventional pressing means for the amount of pressing until the fins are completely formed. The pressing amount is about 50% of the pressing means. In the first pressing means 20, fins are formed, but fins are not completely formed. The remaining 50% is pressed into the final fin shape by the next second pressing means 21.

The grooved plug 2 is integral with the connecting rod 4 and the floating plug 3, and the fin formed by the pressing means 20 is kept in the groove of the grooved plug 2 by the second pressing means. 21 to complete the formation of the fins, the first pressing means 20 and the second pressing means 2
The fins do not shift between the fins. As a result, the shape of the fin is not deteriorated, and the processing accuracy is improved.

Here, assuming that 1/2 of the difference between the outer diameters of the metal tube 1 before and after the pressing means 20 and 21 is the pushing amount Pr, the pushing amount Pr and the diameter Db of the balls 22 and 27 of the pushing means 20 and 21 It is preferable that the ratio Pr / Db with respect to is not more than 0.015.

FIG. 3 is an explanatory view for explaining another embodiment of the method of manufacturing an inner grooved pipe according to the present invention.

The difference from the embodiment shown in FIG. 1 is that notched fins are formed on the inner surface of a metal tube using a mandrel having a plug with a projection connected to the tip.

No pressing means is arranged at the position of the protruding plug 32 connected to the tip of the mandrel 5. A notch is formed in the fin formed by the grooved plug 2 by making the outer diameter of the plug 32 with the protrusion smaller than the outer diameter of the plug 2 with the groove and larger than the diameter of a circle contacting the groove bottom of the plug 2 with the groove. The obtained inner grooved pipe 9a can be obtained.

In the above, since the pushing amount of one set of pressing means is small, the diameter of a ball or a roll can be reduced. As a result, the number of balls or rolls used by one set of pressing means can be increased.

When the processing pitch is the same as the conventional one, the rotation speed of the pressing means with respect to the drawing speed of the metal tube decreases, so that even if the drawing speed is increased, the increase in the rotation speed can be suppressed. When the pushing amount by one set of pressing means is small, the circumferential elongation of the metal tube is small, and the circumferential deformation of the metal tube in the processing portion is small. As a result, lifting of the fin from the grooved plug, displacement of the fin, and the like are suppressed, and a fin having a good shape is formed. The fin shape affects heat transfer performance, brazing during heat exchanger assembly, and the like. If the fin shape is good, adverse effects on performance and brazing are reduced, and a high-quality heat exchanger can be manufactured.

[0039]

In summary, according to the present invention, the following excellent effects are exhibited.

It is possible to provide a method for manufacturing an inner grooved pipe having high processing accuracy and high productivity.

[Brief description of the drawings]

FIG. 1 is an explanatory view for explaining an embodiment of a method for manufacturing an inner grooved pipe of the present invention.

FIG. 2 is an enlarged view of a pressing unit shown in FIG.

FIG. 3 is an explanatory view for explaining another embodiment of the method for manufacturing an inner grooved pipe of the present invention.

FIG. 4 is an explanatory diagram for explaining a conventional method of manufacturing a tube with an inner surface groove.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal tube 2 Slotted plug 3 Floating plug 4 Connecting rod 5 Mandrel 20, 21 Pressing means

Claims (5)

[Claims] 1. A mandrel consisting of a connecting rod having a grooved plug connected to a front end and a floating plug connected to a rear end is inserted into a metal pipe to be internally processed, and the metal pipe is inserted into a drawing die. The floating plug is retained at the position of the drawing die, and the metal tube is passed from the outside while being pressed by a pressing means at the position of the grooved plug on the outlet side of the drawing die, thereby allowing the floating plug to pass through the inner surface of the metal tube. In the method for manufacturing an internally grooved pipe having a plurality of grooves, a plurality of pressing means are arranged in an axial direction of the metal pipe at positions where the grooved plugs of the metal pipe are inserted, and the metal pipe is formed by each pressing means. And a method of manufacturing an inner grooved pipe. 2. The pressing means comprises a ball disposed on the outer periphery of the metal tube, a support member for supporting the ball, and a rotating mechanism for rotating the support member on the outer periphery of the metal tube. The ratio Pr / Db of the pushing amount Pr and the ball diameter Db of the pressing means is set to 0.015 or less, where 1/2 of the difference between the outer diameters of the metal pipes before and after the means is defined as the pushing amount Pr. 2. The method for manufacturing an inner grooved pipe according to item 1. 3. The pressing means comprises a roll disposed on the outer periphery of the metal tube, a support member for supporting the roll, and a rotating mechanism for rotating the support member on the outer periphery of the metal tube. The ratio Pr / Db of the pushing amount Pr and the ball diameter Db of the pressing means is set to 0.015 or less, where 1/2 of the difference between the outer diameters of the metal pipes before and after the means is defined as the pushing amount Pr. 2. The method for manufacturing an inner grooved pipe according to item 1. 4. The method according to claim 1, wherein after the groove is formed on the inner surface of the metal tube by the pressing means, the metal tube is emptied with a plurality of dies to finish it to a predetermined outer diameter. The method for manufacturing a tube with an inner surface according to any one of the above. 5. A notched fin is formed on the inner surface of the metal tube by using a mandrel having a protruding plug formed with a protrusion in a direction opposite to that of the groove of the grooved plug at the tip as the mandrel. 5. The method for manufacturing an inner grooved pipe according to any one of 1 to 4.