JPH10238984A - Internal surface grooved tube, method and apparatus for its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal surface grooved tube very excellent in heat exchange efficiency, and a method and an apparatus for manufacturing it. SOLUTION: An internal surface grooved tube manufacturing apparatus 11 includes outer races 21, 25 rotated integrally with its internal peripheral surfaces 21a, 25a having a mutually similar ellipsoid cross sectional configuration and with phases shifted 90 deg. each other. With a rolling system where 4 rolling balls 17, 18 defined in their rotation orbitals with internal peripheral surfaces 21a, 25a are planetary rotated making contact with an outer peripheral surface of a metal tube 1, an internal surface grooved tube 5 with grooves 5a, 5b formed in the internal surface thereof is manufactured. The grooves 5a, 5b are inclined in different directions and are arranged peripherally alternately with doubly formed groove pattern having a pine needle shape. Further, a boundary of the grooves 5a, 5b can be arranged spirally. For this, the internal surface grooved tube 5 ensures a very excellent heat exchange efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inner grooved tube having a groove pattern formed on the inner surface of a tube, and a method and an apparatus for manufacturing the same. TECHNICAL FIELD The present invention relates to an inner grooved pipe having various types of patterns, and a method and an apparatus for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, for a heat transfer tube used in, for example, a heat exchanger for air conditioning and refrigeration, an inner grooved tube having a groove pattern formed on the inner surface of the tube is used in order to improve the heat exchange efficiency. doing. The following so-called ball rolling method is generally known as a method for manufacturing this kind of inner grooved pipe. That is, the ball rolling method is to insert a grooved plug into a metal tube, move the metal tube in the axial direction, and move a plurality of balls whose rotational trajectory is determined on the inner peripheral surface of the outer race into the metal tube. This is a method in which the diameter of the metal tube is reduced and a groove is formed on the inner surface by rotating the planet while contacting the outer peripheral surface of the metal tube. In this method, a large number of oblique grooves can be formed on the inner surface of the metal tube.

[0003] In recent years, according to JIS revision, a so-called seam pipe manufactured by pipe-forming and welding a metal strip has also become usable as a heat transfer pipe. In the pipe welding method, a groove pattern is formed on the inner surface side of the strip, and the pipe with an inner groove is obtained by pipe welding later. in this case,
A groove pattern having a plurality of types of patterns in the circumferential direction can be formed on the inner surface of the metal tube. For example, it is also possible to set a plurality of virtual boundary lines along the axial direction on the inner surface of the metal tube and alternately arrange diagonal groove patterns in different directions so as to be symmetrical with respect to the virtual boundary lines. . That is, a groove pattern having a shape like a pine needle (hereinafter, referred to as a pine needle groove) can be formed by oblique grooves intersecting the virtual boundary line.

When a pine needle groove is formed in a heat transfer tube, refrigerant flowing along the groove comes to collide on a virtual boundary line,
The heat exchange efficiency can be improved satisfactorily. Further, in recent years, various types of heat exchangers have been studied to use an alternative refrigerant to Freon gas. Along with this, there has been an increasing demand for using the inner grooved tube having the special groove pattern as described above as a heat transfer tube to improve the heat exchange efficiency of the heat exchanger.

[0005]

However, it is not possible to obtain sufficient heat exchange efficiency simply by forming the groove pattern as a pine needle groove. Further, it has been considered to improve the heat exchange efficiency by setting the cross-sectional shape of the groove (fin cross-sectional shape) to a special shape, but this method has a limit. Therefore, the present invention described in claim 1 has been made to provide an inner surface grooved tube having extremely high heat exchange efficiency, which has not been achieved in the past.

Further, a welded portion is formed over the entire length of the inner grooved pipe manufactured by the pipe welding. Since the possibility of refrigerant leakage is higher in this welded portion than in other portions, the reliability and durability are slightly reduced. On the other hand, in the ball rolling method, it is difficult to form a complicated groove pattern on the inner surface of the metal tube, and it has been considered impossible to form a plurality of types of patterns in the circumferential direction. As an improved type of the ball rolling method, it has been considered that a groove forming process is repeated twice by changing the groove direction of the grooved plug to form a so-called cross groove in which a large number of grooves cross each other. The heat exchange efficiency of this cross groove is also inferior to the above-mentioned pine needle groove.

Therefore, the invention according to claim 2 or 3 is:
A manufacturing method or a manufacturing apparatus capable of manufacturing the inner grooved pipe according to claim 1 and manufacturing an inner grooved pipe having excellent characteristics in all of reliability, durability, and heat exchange efficiency. Made with the purpose of providing.

[0008]

Means for Solving the Problems and Effects of the Invention In order to achieve the above object, the invention according to claim 1 is directed to an inner grooved pipe in which an oblique groove pattern is formed on the inner surface of the pipe.
An inner grooved pipe characterized in that the pattern of the groove pattern is different from a boundary portion spirally disposed on the inner surface of the pipe body.

[0009] The inner grooved pipe of the present invention having the above-described structure has an oblique groove pattern on the inner surface of the tube body, and the pattern of the groove pattern is made different at the boundary portion. High heat exchange efficiency. For example, a pine needle groove may be formed by alternately changing the inclination direction of the groove pattern. When the inner grooved tube having such a groove pattern is used as a heat transfer tube, good heat exchange efficiency can be obtained as described above.

In the present invention, the boundary of the groove pattern (which may be linear or have a certain width) is spirally disposed on the inner surface of the tube. Therefore, the inner grooved pipe of the present invention has a structure in which the entire groove pattern spirally turns the inner surface of the pipe body. Therefore, when this inner grooved tube is used as a heat transfer tube, the refrigerant is more appropriately stirred, and the heat exchange efficiency can be further improved. In addition, since the entire groove pattern spirals, the directionality of the inner grooved pipe is lost, which can also improve the heat exchange efficiency.

For example, when a groove pattern is formed symmetrically with respect to a plane including the central axis of the tubular body to form a single pine needle groove, the groove is provided in a direction in which the refrigerant flows to push up the refrigerant. Or the grooves are arranged in the direction in which the refrigerant is pushed down, the characteristics of the heat transfer tube differ greatly. When evaporating the refrigerant, it is better to arrange in the upward direction, when condensing the refrigerant, it is better to arrange in the downward direction,
Each improves the heat exchange efficiency. However, it is almost impossible to make the inner grooved tube used for the heat exchanger or the like have such an ideal arrangement over the entire length. Therefore, there is a limit in improving the heat exchange efficiency.

On the other hand, according to the present invention, the groove pattern turns spirally as a whole. For example, when the single pine needle groove is formed, the mirrored surface of the groove pattern has a structure twisted about the axis of the tubular body. For this reason, the directivity as the whole inner surface grooved pipe is lost. Also, the directionality can be similarly eliminated for multiple pine needle grooves and other groove patterns. Therefore, in the present invention, extremely excellent heat exchange efficiency can be obtained.

The inner grooved pipe of the present invention may be manufactured by the above-described pipe forming welding, or may be manufactured by rolling as described in the following second and third aspects. However, in the former case, a welded portion is formed as described above, and some problems occur in reliability and durability. In addition, it is difficult to manufacture an internally grooved pipe having an asymmetric groove pattern by pipe forming welding according to the present invention. In the latter case, on the other hand, the inner grooved pipe manufactured has no joints such as welds over the entire circumference, so that the inner grooved pipe has good reliability. Has durability.

According to a second aspect of the present invention, a plurality of balls whose rotational trajectories are determined on the inner peripheral surface of the outer race are formed by inserting a grooved plug into the metal tube and moving the metal tube in the axial direction. According to a method of manufacturing an inner grooved tube in which a diameter of the metal tube is reduced and a groove is formed in an inner surface of the metal tube by a rolling method in which a planetary rotation is performed while contacting the outer surface of the metal tube, The surface is a curved surface whose radius from the center of rotation smoothly changes along the circumferential direction, and the pressing amount applied from the ball to the outer peripheral surface of the metal tube is adjusted to a predetermined value to form a groove by the rolling method. Before or after the step of forming the groove, the pattern of the outer periphery of the grooved plug and the rotational phase or the shape of the inner peripheral surface of the outer race are made different from each other to form another groove by the rolling method. The feature is to do To have.

The present applicant has changed the inner peripheral surface of the outer race used in the conventional ball rolling method from a cylindrical surface to a curved surface of another shape, and applied a pressing force applied from the ball to the outer peripheral surface of the metal tube. The inner grooved tube was manufactured while changing the amount in various ways. As a result of this experiment, the inner peripheral surface was formed into a curved surface (e.g., an ellipse) whose radius from the center of rotation smoothly changes along the circumferential direction. It was discovered that a groove pattern was formed only in a part of the circumferential direction. Further, it has been found that, when the amount of pressing is finely adjusted, the portion where the groove pattern is formed can be arranged parallel to the axis of the tube or spirally. The above-mentioned predetermined value was experimentally determined according to the shape of the outer race and the grooved plug, the material of the metal tube, and the like, and good reproducibility was obtained.

In the present invention, the inner peripheral surface of the outer race is
Since the radius from the center of rotation is a curved surface that smoothly changes along the circumferential direction, the amount of pressing applied from the ball to the outer peripheral surface of the metal tube is adjusted to the above-mentioned predetermined value, and the groove is formed by the ball rolling method, An inner grooved pipe having a groove pattern only in a part of the circumferential direction can be manufactured. Further, in the present invention, before or after the groove forming step, the pattern of the outer periphery of the grooved plug and the rotational phase or the shape of the inner peripheral surface of the outer race are both made different from each other, so that the ball rolling method is used. Grooves are formed.

For this reason, in the latter groove forming step, since the outer peripheral pattern of the grooved plug is different from the former, a groove pattern having a different pattern from the former is formed. Also, in the latter groove forming step, since the rotation phase of the outer race or the shape of the inner peripheral surface is different from the former, the groove is formed at a position displaced in the circumferential direction from the former. Therefore, by performing the former groove forming step and the latter groove forming step successively, a groove pattern having a plurality of types of patterns in the circumferential direction can be formed on the inner surface of the metal tube.

When the groove amount is spirally arranged as described above by finely adjusting the amount of pressing, the inner grooved tube according to the first aspect is obtained. Further, in the present invention, the pressing amount may be adjusted so that the portion where the groove pattern is formed is parallel to the axis of the tubular body, and the boundary of the pattern may be disposed parallel to the axis. In any case, the inner grooved pipe manufactured according to the present invention is manufactured by a rolling method, and has no joints such as welds all over the circumference. Therefore, as described above, good reliability and durability can be obtained. Also,
Since the groove pattern has a plurality of types of patterns in the circumferential direction, extremely good heat exchange efficiency can be obtained. That is, according to the present invention, it is possible to manufacture an inner grooved pipe having excellent characteristics in all of reliability, durability and heat exchange efficiency. In particular, in the former case, the inner grooved tube according to claim 1 can be manufactured very easily.

According to a third aspect of the present invention, there are provided a plurality of grooved plugs which are inserted into a metal tube at different positions in the axial direction of the metal tube, and are individually provided around each of the grooved plugs. A plurality of outer races for holding a plurality of balls in contact with the outer peripheral surface of the metal tube around the respective grooved plugs on the inner peripheral surface and rotating the balls by planetary rotation by rotating themselves. In the apparatus for manufacturing an inner grooved pipe, the inner peripheral surface of at least one of the outer races is a curved surface whose radius from the center of rotation smoothly changes along the circumferential direction, and the outer race having the curved surface and a corresponding outer race. The grooved plug is arranged so that at least another set of the outer race and the grooved plug has a rotation phase or an inner peripheral surface shape of each of the outer races and a pattern of the outer circumference of each of the grooved plugs. It is characterized in that the allowed both different.

As described above, the manufacturing apparatus according to the present invention includes a plurality of grooved plugs inserted into the metal tube at different positions in the axial direction, and a plurality of grooved plugs individually provided around each grooved plug. (A member that holds a plurality of balls in contact with the outer peripheral surface of the metal pipe around the respective grooved plugs on the inner peripheral surface and rotates the balls by planetary rotation by itself). Therefore, by rotating each outer race while moving the metal tube in the axial direction, a groove can be formed by the ball rolling method each time the metal tube passes through each grooved plug.

Here, at least one inner peripheral surface of the outer race is a curved surface whose radius from the center of rotation smoothly changes in the circumferential direction. Therefore, by adjusting the amount of pressing applied from the ball to the outer peripheral surface of the metal tube, the outer race and the corresponding grooved plug (hereinafter, referred to as a first outer race and a first grooved plug) are obtained.
Thus, the former groove forming step can be performed. That is, the groove can be formed only in a part of the metal tube in the circumferential direction.

Further, the first outer race and the first grooved plug are provided with at least one other set of the outer race and the grooved plug (hereinafter, referred to as a second outer race and a second grooved plug). The rotational phase or the shape of the inner peripheral surface is different from the pattern of the outer periphery of the grooved plug. For this reason, the latter groove forming step can be performed by the second outer race and the second grooved plug. That is, a groove pattern of a different pattern can be formed at a position displaced in the circumferential direction from the former. The inner peripheral surface of the second outer race may be a cylindrical surface.

Further, as described above, the latter groove forming step and the former groove forming step are continuously performed each time the metal pipe passes through each grooved plug. Therefore, with the manufacturing apparatus of the present invention, the inner grooved pipe can be manufactured by the manufacturing method described in claim 2. Therefore, in the present invention, an inner grooved pipe according to claim 1 and an inner grooved pipe having excellent characteristics in all of reliability, durability and heat exchange efficiency described in relation to claim 2, That is, it is possible to easily manufacture an inner grooved pipe having no joints anywhere along the entire circumference of the pipe and having a plurality of types of circumferential groove patterns on the inner surface of the pipe. The inner grooved pipe according to the first aspect is obtained under the same conditions as those of the second aspect.

[0024]

Next, an embodiment of the present invention will be described with reference to the drawings. First, prior to describing an embodiment of the present invention, a reference example of the present invention will be described. FIG. 5A is a longitudinal sectional view showing a configuration of an inner grooved pipe manufacturing apparatus 51 of a reference example, and FIG. 5B is a sectional view taken along line AA. In addition,
FIG. 5 (A) shows only a configuration (a configuration related to the present invention) of a part of the inner grooved pipe manufacturing apparatus 51 for performing groove processing on the metal pipe 1 sent from a drawing die (not shown). In FIG. 5B, the metal tube 1 and a spindle 69 described later are omitted.

As shown in FIG. 5 (A), the inner grooved pipe manufacturing apparatus 51 includes a grooved plug 53 having a large number of oblique grooves formed on the periphery thereof. The grooved plug 53 is connected via a tie rod 55 to a floating plug (not shown) of the preceding drawing die.
It is rotatable with respect to.

The grooved plug 53 is inserted into the metal tube 1 fed from the drawing die, and four rolled balls 57 are arranged on the outer peripheral surface of the metal tube 1. The rolled balls 57 are held at an interval from each other by the retainer 59, and are in contact with the inner peripheral surface 61 a of the outer race 61. The outer race 61 is fixed to a spindle 69, and rotates integrally with the spindle 69. Then
With the rotation of the outer race 61, the rolled ball 57
Is the inner peripheral surface 61a of the outer race 61 and the metal pipe 1
The planet rotates while contacting the outer peripheral surface of the. The inner peripheral surface 61a of the outer race 61 has an elliptical cross-sectional shape as shown in FIG.

In the inner grooved pipe manufacturing apparatus 51 configured as described above, the outer race 61 is used while rotating the metal pipe 1 while drawing the metal pipe 1 in the direction of arrow P. Then, an oblique groove 3a is formed on the inner surface of the metal tube 1 having passed through the grooved plug 53, and the inner grooved tube 3 is obtained. Here, the present applicant changes the diameter of the inner peripheral surface 61a to variously change the amount of pressing applied from the rolled balls 57 to the outer peripheral surface of the metal tube 1 to manufacture the inner grooved tube 3. went.

As a result, when the pressing amount is adjusted to a predetermined value, as shown in a developed view of FIG. 6, the oblique groove 3a is formed only partially in the circumferential direction over substantially the entire length of the inner grooved tube 3. Found to be formed. This is because, under the above-mentioned pressing amount, the rolled ball 57 disposed on the major axis of the ellipse is in contact with the metal tube 1 and the rolled ball 57 disposed on the minor axis is short.
It is considered that a sufficient amount of pressure is applied to the metal tube 1 to form a groove, and that the rolled balls 57 move around the metal tube 1 with a revolving delay due to planetary rotation.

Further, the applicant of the present application adjusts the above-mentioned pressing amount more finely, and as shown in FIG. 6 (A), arranges the portion where the groove 3a is formed in parallel with the axis of the inner grooved tube 3. Or
As shown in FIG. 6B, it has been discovered that the portion where the groove 3a is formed can be spirally arranged with a twist angle β. Further, the predetermined value of the pressing amount is experimentally determined according to the material of the metal tube 1 and the like unless the design of the inner grooved tube manufacturing apparatus 51 is changed, and it has been found that good reproducibility can be obtained. Therefore, the applicant of the present application considered producing an inner grooved tube having a pine needle groove by a ball rolling method by continuously performing the step of partially forming the groove 3a as described above.

FIG. 1 is a sectional view showing the structure of an inner grooved pipe manufacturing apparatus 11 according to an embodiment of the present invention.
1A is a longitudinal sectional view, FIG. 1B is a sectional view taken along line BB, and FIG. 1C is a sectional view taken along line CC. 1B and 1C, the metal tube 1
And a spindle 29 described later is omitted.

As shown in FIG. 1A, the inner grooved pipe manufacturing apparatus 11 includes a pair of grooved plugs 13 and 14. The grooved plugs 13 and 14 are provided at different positions in the axial direction of the metal tube 1 sent from a drawing die (not shown) at the preceding stage, and have oblique grooves inclined in different directions around the circumference. Are formed in large numbers. The grooved plugs 13 and 14 are connected to a floating plug (not shown) of the drawing die via a tie rod 15, and are connected to the tie rod 15 so as to be individually rotatable. Further, since the metal tube 1 is drawn through the grooved plugs 13 and 14, the upstream grooved plug 13 is formed to have a larger diameter than the downstream grooved plug 14.

The grooved plugs 13 and 14 are inserted into the metal tube 1 described above, and the outer peripheral surface of the metal tube 1 is provided with the grooved plugs 13 and 14.
, Four rolled balls 17 are arranged around the grooved plug 14, and four rolled balls 18 are arranged around the grooved plug 14, respectively. The rolled balls 17 are spaced from each other by the retainer 19 and are in contact with the inner peripheral surface 21 a of the outer race 21. The rolling balls 18 are held at an interval from each other by the retainer 23 and are in contact with the inner peripheral surface 25 a of the outer race 25. The outer races 21 and 25 are configured as an integral rotor member 27, and the rotor member 27 is
It is fixed to.

For this reason, when the spindle 29 is rotated, the outer races 21 and 25 rotate integrally. Then, as the outer races 21 and 25 rotate, the rolling balls 17 and 18 rotate in a planetary manner while contacting the inner peripheral surfaces 21 a and 25 a of the outer races 21 and 25 and the outer peripheral surface of the metal tube 1. Also, the inner peripheral surfaces 21a, 25a of the outer races 21, 25 have similar elliptical cross-sectional shapes as shown in FIGS.
It is off by 0 °.

In the inner grooved pipe manufacturing apparatus 11 configured as described above, the metal pipe 1 is used by rotating the rotor member 27 while drawing the metal pipe 1 in the direction of arrow P. As a result, diagonal grooves 5a and 5b having different directions are sequentially formed on the inner surface of the metal tube 1 each time the plugs 13 and 14 pass through, and the inner grooved tube 5 is formed. Here, in the inner grooved pipe manufacturing apparatus 11, the amount of pressing applied from the rolling balls 17, 18 to the outer peripheral surface of the metal tube 1 is adjusted as described above, and the grooved plugs 13, 1 are adjusted.
Each of the grooves 4 is formed only on a part of the inner grooved tube 5 in the circumferential direction. Also, in this case,
The grooved plugs 13 and 14 form two pairs of grooves 5a and 5b that face each other on the inner surface of the inner grooved tube 5. In the inner grooved tube manufacturing apparatus 11, by adjusting the dimensions and the like of each part,
Each of the grooves 5a and 5b is formed over one fourth of the inner periphery of the inner grooved tube 5.

Inner peripheral surface 21 of outer races 21 and 25
a and 25a are similar to each other and have a phase of 90.
The position at which the grooves 5a and 5b are formed in the inner grooved tube 5 is also shifted by 90 ° because of the shift. For this reason, as shown in the developed view of FIG. 2, a double pine needle groove in which the grooves 5a and 5b alternately appear twice in the circumferential direction is formed on the inner surface of the inner grooved tube 5. Further, since the width of each of the grooves 5a and 5b is 1/4 of the inner circumference of the inner grooved tube 5, the grooves 5a and 5b do not overlap or leave a gap. In this case, too, by finely adjusting the amount of pressing, the boundary between the grooves 5a and 5b can be arranged in parallel with the axis of the inner grooved pipe 5, as shown in FIG. As shown in FIG. 2 (B), the grooves 5a,
5b can be spirally arranged with a twist angle β.

As described above, the inner grooved pipe manufacturing apparatus 11 can easily manufacture the inner grooved pipe 5 in which the groove pattern of the double pine needle groove is formed on the inner surface. When the inner grooved tube 5 in which the double pine flutes are formed is used as a heat transfer tube, the refrigerant flowing along the grooves 5a and 5b collides on the above-mentioned boundary line, and the heat exchange becomes favorable. Efficiency can be improved. Further, in the inner grooved pipe manufacturing apparatus 11, since the inner grooved pipe 5 is manufactured by a ball rolling method, the inner grooved pipe 5 has a joint portion such as a welded portion everywhere over the entire circumference. Absent. Therefore, good reliability and durability can be obtained. That is, the inner grooved pipe manufacturing apparatus 11 can easily manufacture the inner grooved pipe 5 having excellent characteristics in all of reliability, durability, and heat exchange efficiency.

In particular, the boundary between the grooves 5a and 5b is shown in FIG.
When arranged in a spiral as shown in (1), the refrigerant is more appropriately stirred, and the heat exchange efficiency can be further improved.
In addition, since the entire groove pattern spirals, the direction of the inner grooved tube 5 is lost, thereby also improving the heat exchange efficiency. Therefore, the inner grooved tube 5 shown in FIG. 2 (B) can improve the heat exchange efficiency very well when used as a heat transfer tube.

Next, an inner grooved tube 5 (embodiment) shown in FIG. 2B was actually manufactured, and the heat exchange efficiency was compared with a conventional product. The results are shown in FIG. FIG. 3 shows the results of an experiment of evaporating the refrigerant (HCFC-22) using various inner grooved tubes, and measuring the change in the heat transfer coefficient in the tube with respect to the change in the refrigerant mass velocity. In FIG. 3, the measurement results of an inner grooved pipe having a one-way groove manufactured by a conventional ball rolling method (hereinafter referred to as a rolled spiral grooved pipe) are shown by a solid line and a single pipe manufactured by pipe forming welding. The measurement result when the inner grooved pipe having the creasing groove of the present invention (hereinafter referred to as welded creasing grooved pipe) is disposed in the direction of pushing down the refrigerant with respect to the flow of the refrigerant is indicated by a broken line, and the welded creasing grooved pipe is shown. Is shown by a dashed line, and the measurement result of the above embodiment is shown by a two-dot chain line. The fin cross-sections were the same.

As shown in FIG. 3, the heat exchange rate is high in the order of the embodiment, the welded crutch grooved tube arranged in the pushing up direction, the welded crutched grooved tube arranged in the pushing down direction, and the rolled spiral grooved tube. Efficiency was shown. When an inner grooved pipe having double pine needle grooves similar to that shown in FIG. 2 (A) is manufactured by pipe-forming welding and the same experiment is performed, a pipe line between a dashed line and a broken line in FIG. 3 is obtained. It is known from conventional considerations to exhibit properties.
Since it is unlikely that the heat exchange efficiency changes depending on whether it is manufactured by the ball rolling method or by pipe forming welding, FIG.
It is considered that the inner grooved tube 5 shown in FIG.

That is, FIG. 2 shows that the groove pattern has a twist angle β.
In the inner grooved tube 5 of (B), the helical structure of the groove pattern stirs the refrigerant more satisfactorily, and the heat exchange efficiency is extremely improved. When the groove pattern is spirally arranged in this manner, the direction of the inner grooved tube 5 is lost, and when used as a heat transfer tube in an actual heat exchanger, the heat exchange efficiency is lower than that of a conventional product. It is thought that it will improve further.
Thus, the inner grooved pipe manufacturing apparatus 11 can easily manufacture the inner grooved pipe 5 having extremely excellent characteristics in all of reliability, durability, and heat exchange efficiency. In addition, it is difficult to manufacture an inner surface grooved pipe in which the boundary of the pattern is spirally arranged, even by pipe-forming welding. That is, the fact that the inner grooved pipe 5 shown in FIG. 2B can be easily manufactured is a unique operation and effect of the inner grooved pipe manufacturing apparatus 11.

In the above description, the outer races 21 and 25
The above-mentioned amount of pressing is adjusted by changing the diameter of the inner peripheral surfaces 21a, 25a. However, the amount of pressing can be adjusted similarly by changing the diameter of the rolling balls 17, 18. Further, the outer races 21 and 25 may be provided with a well-known adjustment mechanism disclosed in, for example, Japanese Patent Publication No. 3-51491 to adjust the amount of pressing. Further, the revolving period can be changed by changing the diameter of the rolled balls 17 and 18, or the inner peripheral surfaces 21a and 2 can be changed.
Changing the ratio of the major axis to the minor axis (so-called ellipticity) of the ellipse constituting the cross section of 5a changes the appropriate value of the pressing amount. So change these parameters,
The appropriate value may correspond to the amount of pressing applied to the metal tube 1 from the rolling balls 17 and 18. That is, the pressing amount may be indirectly adjusted by changing another parameter.

Further, in the inner grooved tube manufacturing apparatus 11, the amount of pressure applied to the metal tube 1 from the rolled balls 17, 18; the diameter of the rolled balls 17, 18; the ellipticity of the inner peripheral surfaces 21a, 25a; By further changing the phase and the like, the inner grooved pipe 5 shown in FIG. 4 could be manufactured. The inner grooved tube 5 of FIG. 4A has the grooves 5a and 5b formed over a width smaller than 1/4 of the inner circumference, and the grooves 5a and 5b are arranged with a gap. The inner grooved tube 5 in FIG. 4B is formed by forming the grooves 5a and 5b over a width wider than １ ／ of the inner circumference and partially overlapping the grooves 5a and 5b. The inner grooved pipe 5 in FIG. 4C is one in which the boundary between the grooves 5a and 5b meanders by adjusting the above conditions.

FIG. 4D shows the inner grooved pipe 5 manufactured with the inner peripheral surface 21a of the outer race 21 having a circular cross-sectional shape. In this case, the grooved plug 1
3 forms an oblique groove 5a on the inner surface of the metal tube 1 over the entire circumference. By overlapping the groove 5b formed in a part in the circumferential direction as described above, a groove pattern as shown in FIG. 4D is formed. Each of the groove patterns can be formed by turning at a twist angle β. It goes without saying that the conventional fin cross-sectional shape in each groove pattern can be applied to all the shapes.

Furthermore, the present invention is not limited to the above-described embodiment, and can be implemented in various forms without departing from the gist of the present invention. For example, the inner peripheral surfaces 21a and 25a are not limited to those having an elliptical cross-sectional shape, and may have various shapes as long as the radius from the center of rotation smoothly changes along the circumferential direction. For example, it may have a cross-sectional shape of a closed curve represented by the following equation.

R = b + a · cos (n · θ) where r: radius θ: azimuthal angle around the axis of the metal tube 1 n: any integer a, b: any real number satisfying b> a In this case, the metal tube A groove pattern in which the same pattern is repeated n times (for example, an n-fold pine needle groove) can be formed on the inner surface of one. Also, three or more sets of grooved plugs and outer races may be used, and three or more types of groove patterns may be overlapped.

Further, in the inner grooved pipe manufacturing apparatus 11, the outer races 21 and 25 are integrally formed and are integrally rotated by one spindle 29. However, the outer races 21 and 25 are separately formed. Spindles may be provided individually and rotated separately. In this case, by changing the rotation speed of the outer races 21 and 25, more various groove patterns can be formed. In this case, it is preferable that the outer races 21 and 25 are arranged adjacent to each other, and each spindle is provided on both sides thereof. By doing so, the step of forming the groove by the grooved plugs 13 and 14 can be performed continuously, and a better groove pattern can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of an inner grooved pipe manufacturing apparatus to which the present invention is applied.

FIG. 2 is a development view showing a configuration of an inner surface grooved pipe manufactured by the apparatus.

FIG. 3 is an explanatory view showing an effect of the inner grooved pipe.

FIG. 4 is a developed view showing a configuration of another internally grooved tube manufactured by the above-described device.

FIG. 5 is a cross-sectional view illustrating a configuration of an inner grooved pipe manufacturing apparatus according to a reference example of the present invention.

FIG. 6 is a development view showing a configuration of an inner grooved pipe manufactured by the apparatus.

[Explanation of symbols]

1: Metal tube 5: Tube with internal groove
5a, 5b Groove 11 Inner grooved pipe manufacturing apparatus 13, 14 Groove plug 17, 18 Rolled ball 21, 25 Outer race 21a, 25a Inner peripheral surface 27 Rotor member
29 ... Spindle

Claims (3)

[Claims] 1. An inner grooved pipe in which an oblique groove pattern is formed on an inner surface of a tube body, wherein the groove pattern is different from a boundary portion spirally disposed on the inner surface of the tube body. An internally grooved pipe characterized by having 2. Inserting a grooved plug into a metal tube, and moving a plurality of balls whose rotational trajectory is determined on the inner peripheral surface of the outer race on the outer peripheral surface of the metal tube while moving the metal tube in the axial direction. By the rolling method that rotates the planet while making contact,
In the method for manufacturing an inner grooved tube in which the diameter of the metal tube is reduced and a groove is formed in the inner surface of the metal tube, a radius from a rotation center of the inner peripheral surface of the outer race smoothly changes along a circumferential direction. A groove is formed by the above-mentioned rolling method by adjusting a pressing amount applied from the ball to the outer peripheral surface of the metal tube to a predetermined value, and before or after the groove forming step, the outer periphery of the grooved plug is formed. A method of manufacturing an inner grooved pipe, wherein a pattern and a rotational phase of the outer race or a shape of an inner peripheral surface are made different from each other to form another groove by the rolling method. 3. A plurality of grooved plugs which are inserted into the metal tube at different positions in the axial direction of the metal tube, and a plurality of grooved plugs individually provided around each of the grooved plugs. A plurality of outer races that hold a plurality of balls that are in contact with the outer peripheral surface of the metal tube on the inner peripheral surface and rotate each of the balls by planetary rotation by rotating themselves, and manufacturing an inner grooved tube comprising: In the device, the inner peripheral surface of at least one of the outer races is a curved surface whose radius from the center of rotation smoothly changes along the circumferential direction, and the outer race having the curved surface and the corresponding grooved plug are provided with: For at least one other set of the outer race and the grooved plug, the rotational phase or the shape of the inner peripheral surface of each outer race and the outer peripheral pattern of each of the grooved plugs are different. DOO apparatus for producing inner grooved tube, wherein.