JPH1110268A - Production of outer face grooved tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an outer face grooved tube producing method capable of forming a smooth part of an outer diameter larger than an outer diameter of a groove working part of a tube while preventing tube deformation and uneven groove forming at the time of producing the outer face grooved tube by knurl form rolling. SOLUTION: While drawing a metal tube stock 1 in one direction, the tube stock 1 is reduced in a prescribed quantity by conducting planetary rotation/ pressing a reducing roll 2 having a smooth outer peripheral face on the tube stock 1. Immediately thereafter, a groove working roll 3, which is knurled to the outer peripheral face, is subjected to planetary rotation/pressed on the tube stock 1, at a state a reducing quantity of the reducing part of the tube stock 1 reduced by the reducing roll 2 is suppressed to a minute quantity, many grooves 10 are worked on an outer peripheral face of the reduced part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an externally grooved tube (heat transfer tube) used in, for example, a shell-and-tube type heat exchanger.

[0002]

2. Description of the Related Art One of the methods for manufacturing an outer grooved tube having a large number of grooves on an outer peripheral surface includes, for example, as shown in FIG.
While pulling out the metal pipe 1 along one direction a, the groove processing rolls 3 arranged at a constant angular interval around the raw pipe 1 are planetary-rotated, and the groove processing roll 3 is pulled out of the raw pipe. There is a so-called knurl rolling method in which a large number of parallel ridges 30 knurled on the outer peripheral surface of the grooving roll 3 are transferred to the outer peripheral surface of the raw tube 1 to press the grooves 10. . The groove processing rolls 3 are arranged at an angle interval of usually 120 ° with respect to the raw tube 1. In the above method, when the raw tube 1 is made of a relatively soft material such as a copper tube or a copper alloy tube, a plug 4 is inserted into the raw tube 1 and the peripheral wall of the raw tube 1 is Groove processing is performed in such a manner as to press against the surface of the plug 4. The ridges 30 formed on the outer peripheral surface of the grooving roll 3 are formed in parallel with the axis 31 of the roll 3 or the shaft 31
Is formed in a state having a predetermined twist angle (75 ° or less). When a smooth unprocessed portion without a groove is required on the outer peripheral surface of the tube 1, the grooved roll 3 is separated from the raw tube 1 in the radial direction at this portion of the raw tube 1 so that Form a smooth unprocessed part.

[0003] As another method of manufacturing an outer grooved tube, there is a method described in, for example, JP-A-59-100396. The production method described in the above publication,
As shown in FIG. 14, while inserting the plug 4 into the metal tube 1 and pulling out the tube 1 along one direction a,
While rotating the rolling tools 5 arranged at a constant angular interval (120 °) around the raw tube 1 in planetary rotation, the rolling tools 5
Is pressed against the raw tube 1 to form a spiral groove 10 on the outer peripheral surface of the raw tube 1 while reducing the diameter thereof. As shown in the figure, the rolling tool 5 is constituted by a large number of disks 50 each having a diameter gradually reduced toward the rear in the drawing direction.
0 into the outer wall of the tube 1
A spiral groove 10 is formed on the outer peripheral surface of the raw tube 1,
The fins 11 are formed so that the pipe wall in the portion between the grooves 10 is raised in the outer peripheral direction. When a smooth unfinished portion without fins is required on the outer peripheral surface of the tube 1, the rolling tool 5 is separated from the outer surface of the tube 1 in the radial direction at the relevant portion of the tube 1 by separating the rolling tool 5 from the tube 1 in the radial direction. Form a smooth unprocessed part.

[0004] The difference between the knurl rolling method and the fin rolling method described above is as follows. According to the knurl rolling method, the raw pipe 1 is formed by the groove processing roll 3.
When the groove 10 is machined on the outer peripheral surface of the pipe, the ridge 30 of the groove machining roll 3 is pushed into the pipe wall of the raw tube 1 as shown in FIG.
Since the fins 11 are formed by raising the pipe wall between the adjacent ridges 30 in the outer circumferential direction, the outer diameter of the pipe formed by the tops of the many fins 11 is equal to the outer diameter of the portion where the outer surface of the raw pipe 1 is smooth. Larger than the diameter. Further, although there is a limit to the depth of the groove 10, it is suitable for processing the thin groove 10 having a small thickness at a high speed. On the other hand, according to the fin rolling method, the spiral fins 11 are formed on the outer peripheral surface of the raw tube 1 while reducing the diameter of the raw tube 1 by the large number of disks 50 forming the rolling tool 5 as described above. The outer diameter formed by the tops of the many fins 11 is smaller than the outer diameter of the base tube 1, so that the groove 10 can be formed deeply.
If the thickness of the groove is small, the groove 10 cannot be machined, and the machining speed is much lower than the former method.

[0005]

When the outer grooved tube is incorporated into a shell-ant tube type heat exchanger, a plurality of tube plates of the shell are formed with holes through which the heat transfer tubes penetrate, and grooves are formed in the holes. Insert the heat transfer tube in a state where the unprocessed portion where no heat is formed is located, expand the unprocessed portion of the groove of the heat transfer tube (by using a pipe expansion tool), and fix the unprocessed portion of the groove of the heat transfer tube tightly to each hole of the tube sheet doing. In order to incorporate the outer grooved tube into the shell and tube type heat exchanger, it is necessary to form a non-grooved unprocessed portion on a required portion of the outer peripheral surface of the tube as described above. According to the method, when manufacturing an outer grooved tube having a non-grooved portion at a required portion, the grooved portion has a slightly larger outer diameter than the ungrooved portion, so the pipe is inserted into the hole of the tube sheet. There is a problem that the fins between the grooves on the outer peripheral surface of the pipe are broken when the pipe cannot be inserted or when the pipe is inserted into the hole of the pipe sheet, and the heat transfer performance is reduced. In order to solve such a problem, when a plug 4 having an outer diameter smaller than the inner diameter is inserted into the raw tube 1 to perform groove processing while reducing the diameter of the raw tube 1 by the groove processing roll 3, Since the clearance between the inner diameter of the tube and the outer diameter of the plug is large, there occur problems such as that a groove having a uniform size is not formed stably and the tube is deformed non-circularly.

On the other hand, when an outer grooved tube having a groove-unprocessed portion in a required portion is manufactured by the above-described fin rolling method, the groove-unprocessed portion of the heat transfer tube is smaller than the outer diameter of the groove-processed portion. Is also a large diameter, so there is no such problem as described above, but it is not possible to reduce the wall thickness of the tube, so the heat exchanger becomes large, and the productivity decreases significantly in terms of processing speed. was there.

SUMMARY OF THE INVENTION An object of the present invention is to form an outer-grooved tube by a knurl rolling method in which the outer diameter of a groove-unprocessed portion is made larger than the outer diameter of a fin top formed in a groove-processed portion of the tube. It is an object of the present invention to provide a method for manufacturing an externally grooved tube that can be manufactured. Another object of the present invention is to provide a method for manufacturing an externally grooved tube that can prevent deformation and uneven groove formation of the tube.

[0008]

SUMMARY OF THE INVENTION A method of manufacturing an externally grooved tube according to the present invention is configured as follows to solve the above-mentioned problems. In other words, in the method for manufacturing an outer grooved tube according to claim 1, the diameter reducing roll 2 having a smooth outer peripheral surface is drawn while the metal raw tube 1 is pulled in one direction.
A diameter reducing step of pressing the planetary tube 1 by a predetermined amount while rotating the planetary tube with respect to a predetermined diameter, and immediately after the diameter reducing step, the grooved roll 3 knurled to the outer peripheral surface is applied to the raw tube 1. Pressing while rotating the planet, the roll for diameter reduction 2
A large number of grooves 1 are formed in the outer peripheral surface of the reduced diameter portion in a state where the amount of reduced diameter of the reduced diameter portion of the raw tube 1 reduced by the above is suppressed to a very small amount.
0 processing.

The method of manufacturing an outer grooved pipe according to claim 2 is the method of manufacturing a pipe with outer diameter groove according to claim 1, wherein
The outer peripheral surface of the diameter reducing roll 2 on the side where the pressing force of the groove processing roll 3 against the raw tube 1 is continuous with the tops of a number of the ridges 30 formed on the outer peripheral surface of the groove processing roll 3. It is characterized in that it is located between the extended surface and the extended surface in which the bases (groove bottoms) of the plurality of ridges 30 are continuous.

[0010] In a third aspect of the present invention, there is provided the method of manufacturing an outer grooved tube according to the first aspect, wherein the diameter reducing roll 2 is used.
And the groove processing roll 3 are coaxially continuous or adjacent to each other, and the diameter of the diameter reducing roll 2 is
Are formed to be smaller than the outer diameter formed by the tops of the plurality of ridges 30 formed on the outer peripheral surface and larger than the diameter formed by the bases (groove bottoms) of the plurality of ridges 30. And

In the method of manufacturing an externally grooved tube according to the present invention, a plurality of sets of groove processing rolls 3 and 3a are sequentially arranged along the drawing direction of the raw tube 1 to the outer peripheral surface of the raw tube 1 immediately after diameter reduction. Spiral grooves having different torsion angles can be formed in order. In this case, the diameter formed by the tops of the ridges 30 of the groove processing roll 3a at the front position in the pulling direction and the diameter formed by the bases of the ridges 30 at the front position in the drawing direction behind the roll 3a are determined. Grooving roll 3
(A groove processing roll that first comes into contact with the reduced diameter portion of the raw tube 1) is formed to be slightly smaller than the diameter formed by the tops of the ridges 30 and the diameter formed by the bases of the ridges 30 respectively.
It is preferable to first form a deep groove 10 on the outer peripheral surface of the raw tube 1 immediately after the diameter reduction, and then to form a slightly shallow groove 10 a so as to cross the groove 10. Thus, the deep groove 1
By forming the shallow groove 10 next to 0, it is possible to prevent the fin tops between the initially formed grooves 10 from being broken. In such a case, claims 2 and 3
In the above, the position of the outer peripheral surface on the pressing force action side of the diameter reducing roll 2 or the outer diameter of the diameter reducing roll 2 is based on the groove processing roll 3 having the larger diameter formed by the tops of the ridges 30. Set.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION

1st Embodiment With reference to FIGS. 1-5, the 1st Embodiment of the manufacturing method of the outer surface grooved pipe by this invention is described. FIG. 1 is a partial cross-sectional view showing a knurl rolling apparatus for performing the manufacturing method according to the first embodiment and a pipe being processed, FIG. 2 is a cross-sectional view taken along arrow AA in FIG. 1, and FIG. 1 is an enlarged cross-sectional view of a diameter reducing roll and a groove processing roll of the apparatus of FIG. 1; FIG. 4 is a half cut front view of an outer grooved pipe manufactured by the apparatus of FIG. 1; FIG. 4 is an enlarged view schematically showing a state in which a groove is formed.

As shown in FIGS. 1 and 2, a diameter reducing roll 2 having a smooth outer peripheral surface and a predetermined outer circumferential surface with respect to an axial center of a drawn portion of the metal tube 1 are provided. Grooving roll 3 on which a number of parallel ridges 30 having a twist angle are formed
And one set of each of them are installed at an angular interval of 120 °. The groove processing roll 3 is installed so as to approach the front side in the pulling-out direction of the diameter reducing roll 2. In this embodiment, each of the diameter reducing rolls 2 and the groove processing rolls 3 located at the same position along the drawing direction are mounted on a processing stand (not shown) while being attached to the same shaft 20, and are not shown. The actuator is configured so as to be able to approach and separate toward the drawing center (tube axis) within a predetermined range by an actuator, and to rotate planetarily with respect to the drawing center by a driving mechanism.

As shown in FIG. 3, the diameter R2 of the diameter reducing roll 2 is larger than the outer diameter R3 formed by the tops of a number of the ridges 30 formed on the outer peripheral surface of the groove processing roll 3. It is smaller and larger than the diameter r3 formed by the bases (groove bottoms) of the plurality of ridges 30. That is, on the action side of the pressing force of the rolls 2 and 3 against the raw tube 1,
The outer peripheral surface of the diameter-reducing roll 2 is located between the mutually extending surfaces of the tops of the numerous ridges 30 of the groove forming roll 3 and the mutually extending surfaces of the bases of the ridges 30.

When the outer peripheral surface of the raw tube 1 is grooved, the plug 4 attached to the plug rod 40 is inserted into the raw tube 1.
While pulling out the raw tube 1 in the direction of arrow a in FIG. 1, while rotating each of the diameter reducing rolls 2 and each of the groove forming rolls 3 with respect to the raw tube 1, the outer peripheral wall of the raw tube 1 is removed. Plug 4
Press against the outer peripheral surface of. When it is necessary to form a groove unprocessed portion on the outer peripheral surface of the pipe, each time the diameter reducing roll 2 and each processing roll 3 are separated from the raw pipe 1 in the radial direction for a predetermined time. According to this method, the tube 1 is reduced in diameter by each of the rolls 2 for diameter reduction, and immediately after that, the ridges 30 of the groove processing rolls 3 are transferred to the outer peripheral surface of the reduced diameter portion, thereby obtaining the structure shown in FIG. As described above, the outer peripheral surface has a large number of grooves 10 having a predetermined torsion angle with respect to the tube axis, and a required portion is a smooth portion 1 which is a groove unprocessed portion.
2 is manufactured. A smooth portion 13 having a length corresponding to the rear end of the diameter-reducing roll 2 and the rear end of the groove forming roll 3 is formed at the rear end of the groove forming region at the rear end in the drawing direction. An incompletely machined portion in which the diameter is reduced and grooved only by the grooving roll 3 at the front end portion in the drawing direction (portion where the groove is incompletely machined)
13a are formed.

The above-described diameter reduction of the raw tube 1 and the subsequent groove processing on the reduced diameter portion are performed in the following manner. As shown schematically in an enlarged manner in FIG. 5, the raw tube 1 is first reduced in diameter from the two-dot chain line state in FIG. 5 to the solid line state by the outer peripheral surface of the diameter reducing roll 2. Next, a large number of ridges 30 of the groove processing roll 3 are pushed into the outer peripheral surface of the raw tube 1, and the pipe wall of the portion is raised on the groove side between the ridges 30,
A groove 10 corresponding to the ridge 30 is formed. The outer peripheral surface of the diameter-reducing roll 2 is, on the working side of the pressing force, an extended surface formed by a large number of the ridges 30 of the groove processing roll 3 and an extended surface formed by the grooves 31 at the base of the many ridges 30. In the process of forming the groove 10 on the outer peripheral surface of the raw tube 1, the diameter-reduced portion of the raw tube 1 is only reduced to an extremely small amount by the groove processing roll 3. .

The externally grooved tube 1a manufactured as described above is
The outer diameter of the smooth portion 12 is larger than the outer diameter of the portion where the groove 10 is formed on the outer peripheral surface (the outer diameter formed by the fin tops between the grooves 10). Therefore, the outer grooved tube is inserted into the hole of the tube sheet so that the smooth portion 12 is located in the hole (not shown) of the tube sheet of the shell (this hole is formed slightly larger than the outer diameter of the smooth portion 12). When the flattened portion 12 is expanded with a pipe expansion tool (not shown) and fixed to the hole in close contact with the hole, the grooved portion of the tube does not become unable to be inserted into the hole. Since the fin tops are not destroyed, the shell-and-tube heat exchanger can be assembled without deteriorating the heat transfer performance of the outer grooved tube 1a. The grooved portion of the raw tube 1 has been reduced in diameter by a predetermined amount by a diameter reducing roll 2 in advance, and when the grooved portion is grooved by the grooved roll 3, the reduced diameter portion is only slightly reduced in diameter. Therefore, stable and more uniform groove processing can be performed without deforming the reduced diameter portion into a non-circular shape by the groove processing. Since the groove processing is performed on the outer peripheral surface of the reduced diameter portion immediately after the reduced diameter, the smooth portion 13 of the reduced diameter portion shown in FIG. The decrease can be minimized. Further, since the diameter reducing roll 2 and the groove processing roll 3 are mounted coaxially, their pressing force and other controls are easy.

EXAMPLE A phosphor-deoxidized copper tube having an outer diameter of 15.88 mm and a wall thickness of 0.75 mm was used as the raw tube 1, and the outer diameter was 13.60 mm inside the raw tube 1.
The outer diameter φR2 = 18.00 mm formed by a set of three diameter reducing rolls 2 each of which has a single outer diameter φR2 = 18.50 mm and a thickness of 10 mm.
mm, the outer diameter φr3 formed by the bases of the ridges 30 = 18.
00mm, height 0.50mm, helix angle 20 °, number of ridges 5
A set of three groove processing rolls 3 having a thickness of 10 mm and both sides taken out was used. Then, each of the diameter reducing rolls 2 and each of the groove processing rolls 3 are uniformly pressed against the outer peripheral surface of the raw tube 1, and the rolls 2, 3 are separated from the raw tube 1 by the same amount at the necessary portions at the same time. An outer surface grooved tube was manufactured by setting the planetary rotation speed at 500 rpm and the tube drawing speed at 2 m / min. According to this procedure, the maximum outer diameter φ15.80 mm formed by the fin tops between the grooves 10, the outer diameter φ14.80 mm formed by the bottoms of the grooves 10, the depth 0.50 mm of the grooves 10, and the twist angle 20 °, number of grooves 42, groove bottom thickness 0.50m
m, an outer grooved tube having an outer diameter of 15.30 mm and an inner diameter of 13.80 could be manufactured.

Second Embodiment FIG. 6 is a partial cross-sectional view showing a knurl rolling apparatus for performing a manufacturing method according to a second embodiment and a pipe being processed.
In this embodiment, around the drawing center of the raw tube 1, 12
A set of three diameter reducing rolls 2 and a set of three groove forming rolls 3 and 3a arranged at equal angular intervals of 0 ° are sequentially installed closer to each other from the rear in the drawing direction. The diameter reducing roll 2 and the groove processing rolls 3 and 3a are mounted on the same shaft 20. Each diameter reduction roll 2 and each groove processing roll 3, 3a are:
It is installed so that it can be planet-rotated at the same speed with respect to the base tube 1 and can simultaneously approach and separate in the direction of the tube axis. The ridges 30, 30 on the outer peripheral surfaces of the groove processing rolls 3 and 3a have the same twist angle and different twist directions.

As shown in FIG. 1, a plug is inserted into the tube 1 and the rolls 2, 3, and 3a are pulled out of the tube 1 while pulling out the tube 1 in the direction of arrow a in FIG. While rotating, the raw material tube 1 is pressed against the outer peripheral wall of the raw material tube 1, and the diameter of the raw material tube 1 is reduced uniformly by a small amount by each of the diameter reducing rolls 2. Forming a large number of grooves 10 twisted in a predetermined direction with respect to the pipe axis, and then forming a large number of grooves 10a twisted in a direction opposite to the groove 10 by each groove processing roll 3a, thereby reducing the diameter of the groove. The outer grooved pipe 1a having a cross groove is manufactured.

In this embodiment, the diameter formed by the tops of the ridges 30 of the grooving roll 3 that first comes into contact with the reduced diameter portion of the raw tube 1 and the diameter formed by the bases of the ridges 30 are: Next, the diameter of the ridge 30 of the groove processing roll 3a that comes into contact with the reduced diameter portion is slightly larger than the diameter formed by the tops of the ridges 30 and the diameter formed by the bases of the ridges 30. Is smaller than the diameter formed by the tops of the ridges 30 of the groove processing roll 3 that first comes into contact with the reduced diameter portion of the raw tube 1, and is larger than the diameter formed by the bases of the ridges 30. Is set. With such a configuration, the fin tops between the grooves 10 initially formed on the surface of the reduced diameter portion of the base tube 1 (fin tops other than the portions where the grooves 10a are formed).
Is prevented from being broken by the groove processing roll 3a that comes into contact with the surface of the reduced diameter portion. Other configurations, operations, and effects of the manufacturing method according to the second embodiment are the same as those of the manufacturing method according to the first embodiment, and a description thereof will be omitted.

Third Embodiment FIG. 7 is a partial cross-sectional view showing a knurl rolling apparatus and a pipe being processed for implementing the manufacturing method according to the third embodiment. FIG. It is an enlarged view which shows typically the positional relationship of the outer peripheral surface of a roll and the pressurizing force action direction of a grooving roll. In the manufacturing method of this embodiment, the diameter of each groove processing roll 3 is larger than the outer diameter of each diameter reducing roll 2, and these rolls 2, 3 are separate shafts 20, 32, respectively.
Attached to. Other configurations are almost the same as those in the first embodiment.

Each of the diameter reducing rolls 2 and each of the groove processing rolls 3 in this embodiment have different diameters and different shafts 2.
8, the rotation axis P2 of the diameter reducing roll 2 is closer to the center of the planetary rotation than the rotation axis P3 of the groove processing roll 3, as shown in an enlarged manner in FIG. Position. In such a case, on the side where the pressing force of each of the rolls 2 and 3 against the raw pipe (not shown) acts (the lower side in FIG. The surface 21 is always located between the extension surface 33 formed by the tops of the ridges 30 of the groove processing roll 3 and the extension surface 34 formed by the bases (groove bottoms) of the ridges 30. Designed.

As shown in FIG. 7, a plug similar to that shown in FIG. 1 is inserted into the raw tube 1 and the raw tube 1 is pulled out in the direction of arrow a.
When each of the diameter reducing rolls 2 and each of the groove processing rolls 3 are planetary-rotated while maintaining the positional relationship shown in FIG. 8, and each of the rolls 2 and 3 is pressed against the outer peripheral surface of the raw tube 1, the raw tube 1 is contracted. The diameter is reduced by a predetermined amount by the diameter roll 2, and immediately after the diameter is reduced, the ridges 30 of the groove processing roll 3 are transferred to the outer peripheral surface of the reduced diameter portion, whereby a number of parallel grooves 10 are formed on the surface of the reduced diameter portion. The outer grooved pipe 1a having the above is manufactured. In a necessary portion, by separating the diameter reducing roll 2 and the groove processing roll 3 from the raw tube 1 for a predetermined time, a smooth portion having an outer diameter larger than the groove processing portion is formed in the outer surface grooved tube 1a. In the manufacturing method of this embodiment, on the side on which the pressing force of each of the rolls 2 and 3 against the raw tube is applied, the outer peripheral surface 21 of the diameter reducing roll 2 is arranged such that the tops of the respective ridges 30 of the grooved roll 3 are mutually opposed. Since it is designed so that it is always located between the extension surface 33 and the extension surface 34 formed by the bases (groove bottoms) of the ridges 30, the diameter of the base tube 1 is reduced by the diameter reducing roll 2. Immediately thereafter, when the groove 10 is formed on the surface of the reduced diameter portion by the groove processing roll 3, the reduced diameter portion is only reduced in diameter by a small amount. Other operations and effects of the manufacturing method of this embodiment are almost the same as those of the manufacturing method of the first embodiment, and the description thereof will be omitted.

Fourth Embodiment FIG. 9 is a partial cross-sectional view showing a knurl rolling apparatus for performing a manufacturing method according to a fourth embodiment and a pipe being processed.
According to the manufacturing method of this embodiment, in the apparatus of the second embodiment, the grooving roll 3a that comes into last contact with the raw tube 1 is formed to have a larger diameter than the grooving roll 3 that comes into contact with first, and the front and rear in the drawing direction. Roll 2 adjacent at one side
And the groove processing roll 3 are mounted on the same shaft 20, and the groove processing roll 3 a is mounted on another shaft 32.

The outer diameter of the diameter reducing roll 2 is smaller than the diameter formed by the tops of the ridges 30 on the outer peripheral surface of the adjacent groove processing roll 3 and is smaller than the diameter formed by the bases of the ridges 30. It is formed large. On the side where the pressing force of the grooving rolls 3 and 3a against the raw pipe 1 is applied, the ridges 3 of the grooving roll 3a
The extended surfaces formed by the apex portions 0 are slightly away from each other in the direction of the axis 32 than the extended surfaces formed by the ridges 30 of the groove processing roll 3 adjacent to the diameter reducing roll 2. Have been.

A plug similar to that of the embodiment shown in FIG. 1 is inserted into the raw tube 1, and the raw tube 1 is pulled out in the direction of arrow a in FIG. By pressing the groove processing roll 3a adjacent to the front thereof against the outer circumferential surface thereof while rotating the planetary roll with respect to the raw tube 1, the surface of the reduced diameter portion of the raw tube 1 reduced in diameter by the diameter reducing roll 2 Then, an outer grooved pipe 1a having a number of cross grooves 10, 10a is manufactured. At the beginning of the manufacturing process and in the process, the rolls 2, 3, and 3a are separated from the raw tube 1 for a predetermined time to form a large-diameter smooth portion at a necessary portion. Other configurations, operations and effects of this embodiment are the same as those of the second embodiment.
The description is omitted because it is almost the same as that of the embodiment.

Fifth Embodiment FIG. 10 is a partial cross-sectional view showing a knurl rolling apparatus for performing a manufacturing method according to a fifth embodiment and a pipe being processed. In this embodiment, since a large number of ridges 30 are formed on the outer peripheral surface of the grooving roll 3 in a state of crossing at a predetermined twist angle, a plug is inserted into the raw tube 1 to remove the raw tube 1. When each of the rolls 2 and 3 is pressed against the outer peripheral surface of the tube 1 while being pulled out in the direction of the arrow a while rotating planetarily, a large number of cross-shaped grooves 10 are formed in the reduced diameter portion reduced by the diameter reducing roll 2. The outer grooved pipe 1a having the above is manufactured. The manufacturing method of this embodiment is similar to the manufacturing method of the second embodiment except that a cross-shaped groove 10 can be formed on the outer peripheral surface of the raw tube 1 by one groove processing roll 3. Since the manufacturing method is almost the same as that of the embodiment, the description thereof is omitted.

Sixth Embodiment FIG. 11 is a partial cross-sectional view showing a knurl rolling apparatus for performing a manufacturing method according to a sixth embodiment and a pipe being processed. In the manufacturing method according to this embodiment, the dies 7 are installed along the drawing direction of the raw tube 1, and the diameter reducing rolls 2 and the groove processing rolls 3 having substantially the same configuration as the first embodiment.
Are installed at intervals of 120 degrees, and a floating plug 7 connected to each other by a connecting shaft 41 and a plug 4 smaller in diameter than the floating plug 7 are placed in the raw tube 1 with the die 7 and each of the rolls 2, 3. Insert at the position corresponding to. While pulling out the raw tube 1 in the direction of the arrow a in the drawing, each of the diameter reducing rolls 2 and the groove forming rolls 3 are pressed against the raw tube 1 while rotating planetarily, and the raw tube 1 is pressed with the floating plug 6 and the die 7. The outer diameter grooved pipe 1a is formed by reducing the diameter with the diameter reducing roll 2, the groove processing roll 3 and the plug 4 and forming a groove on the surface of the reduced diameter portion.
Is configured to be manufactured. When forming a large-diameter smooth portion in a required portion of the outer grooved tube 1a, separate the diameter reducing rolls 2 and the groove processing rolls 3 from the reduced diameter raw tube 1 in a required time radial direction. .

In general, a small-diameter copper base tube is wound in a long coil shape. In the manufacturing method of the first to fifth embodiments, the base tube 1 is limited to a straight tube. The material must be stretched and cut to length to be used.
Each time the groove processing for one raw pipe is completed, the next raw pipe must be set, which increases the cost. In this respect, according to the manufacturing method of the sixth embodiment, the coil-shaped raw tube can be used as it is, and it can be cut every time it is processed over a certain length, and can be transferred to the next processing.
The operation rate and productivity can be further improved. Other configurations, operations, and effects in the manufacturing method of this embodiment are as follows.
The description is omitted because it is almost the same as the first embodiment.

Other Embodiments In the manufacturing method according to the present invention, grooves can be formed on the outer peripheral surface of not only copper or copper alloy tubes but also aluminum-based tubes, iron-based tubes, and stainless steel tubes. First to fifth
In the embodiment, for example, when a groove is formed in the outer peripheral surface of a hard metal pipe such as an iron or stainless steel pipe, it is not necessary to insert a plug into the pipe. Further, the diameter reducing roll 2 and the groove processing roll 3 can be continuously and integrally formed.

[0032]

According to the method for manufacturing an outer surface grooved pipe according to the first aspect, immediately after the diameter of the raw tube 1 is reduced by the diameter reducing roll 2 whose outer peripheral surface is smooth, the outer peripheral surface is knurled. Since the groove is formed on the outer peripheral surface of the reduced diameter portion in a state where the reduced diameter of the reduced diameter portion is suppressed to a minute amount by the processing roll 3, the groove is formed on the outer peripheral surface while preventing deformation and uneven groove processing of the pipe. An outer grooved tube having a smooth portion having a larger diameter than a portion in a required portion can be manufactured with high productivity. Further, since the groove is formed in the reduced diameter portion immediately after the diameter reduction of the raw tube 1, the unprocessed portion of the groove in the reduced diameter portion can be minimized.

According to the manufacturing method of the outer grooved pipe according to the second aspect, the outer circumference of the diameter reducing roll 2 is on the side of the pressing force of the diameter reducing roll 2 and the groove processing roll 3 against the raw tube 1. An extended surface in which the tops of a number of the ridges 30 formed on the outer peripheral surface of the groove processing roll 3 are continuous, and an extended surface in which the bases (groove bottoms) of the plurality of ridges 30 are continuous. Therefore, the manufacturing method of claim 1 can be more smoothly and reliably performed.

According to the method of manufacturing an outer grooved pipe according to the third aspect, the diameter reducing roll 2 and the groove processing roll 3 are coaxially continuous or close to each other, and The diameter is smaller than the outer diameter formed by the tops of the multiple ridges 30 formed on the outer peripheral surface of the groove processing roll 3, and is smaller than the diameter formed by the bases (groove bottoms) of the multiple ridges 30. Since it is formed large, the manufacturing method of claim 1 can be smoothly and reliably implemented, and the diameter reducing roll 2 and the groove processing roll 3 can be operated at the same time. Is easier.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing a knurl rolling apparatus and a pipe being processed for implementing a manufacturing method according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along arrows AA in FIG.

FIG. 3 is an enlarged sectional view of a diameter reducing roll and a groove processing roll of the apparatus of FIG.

FIG. 4 is a half cut front view of an externally grooved tube manufactured by the apparatus of FIG. 1;

FIG. 5 is a partially enlarged view schematically showing a state in which the raw pipe is reduced in diameter and grooved by the apparatus of FIG. 1;

FIG. 6 is a partial cross-sectional view showing a knurl rolling apparatus and a pipe being processed for performing the manufacturing method of the second embodiment.

FIG. 7 is a partial cross-sectional view showing a knurl rolling apparatus and a pipe being processed for performing the manufacturing method of the third embodiment.

8 is a partially enlarged view schematically showing the positional relationship between the outer circumferential surface of the processing device of FIG. 7 in the pressing force acting direction of the diameter reducing roll and the groove processing roll.

FIG. 9 is a partial cross-sectional view showing a knurl rolling apparatus and a pipe being processed for performing a manufacturing method according to a fourth embodiment.

FIG. 10 is a partial cross-sectional view showing a knurl rolling apparatus and a pipe being processed for performing a manufacturing method according to a fifth embodiment.

FIG. 11 is a partial cross-sectional view illustrating a knurl rolling apparatus and a pipe being processed for performing a manufacturing method according to a sixth embodiment.

FIG. 12 is a partial cross-sectional view showing a knurled rolling apparatus and a pipe being processed for explaining a conventional method of manufacturing a grooved pipe with external surfaces.

FIG. 13 is a partially enlarged view schematically showing a state where a groove is formed in a raw pipe by the apparatus of FIG. 12;

FIG. 14 is a partial cross-sectional view showing a fin rolling apparatus and a pipe being processed for explaining a conventional method for manufacturing a pipe with external grooves (fins).

[Explanation of symbols]

 a Arrow R2 Outer diameter of roll for diameter reduction R3 Diameter formed by the tops of the ridges of the groove processing roll r3 Diameter formed by the bases of the ridges of the groove processing roll P2, P3 Rotation axis 1 Elementary tube 1a Outer surface groove Attached pipe 10, 10a Groove 11 Fin 12 Large-diameter smooth portion 13 Smooth portion 13a Incompletely machined portion 2 Roll for reducing diameter 20 Shaft 3, 3a Grooving roll 30, 30a Protrusions 31 Groove 32 Shaft 4 Plug 40 Plug rod 41 Connecting shaft 5 Rolling tool 50 Disc 6 Floating plug 7 Dice

Claims (3)

[Claims] 1. While pulling out a metal tube 1 in one direction, a diameter-reducing roll 2 having a smooth outer peripheral surface is pressed against the tube 1 while rotating in a planetary manner against the tube 1 to reduce the tube 1 by a predetermined amount. Immediately after the diameter reducing step, the grooving roll 3 knurled to the outer peripheral surface is pressed against the raw tube 1 while rotating planetary, and is reduced by the diameter reducing roll 2. And forming a large number of grooves 10 on the outer peripheral surface of the reduced diameter portion in a state where the reduced diameter of the reduced diameter portion of the raw tube 1 is suppressed to a very small amount. Production method. 2. The roll 2 for reducing diameter and the roll 3 for forming grooves.
On the side of the pressing force acting on the raw tube 1, the outer peripheral surface of the diameter reducing roll 2 is an extended surface formed by connecting the tops of a number of ridges 30 formed on the outer peripheral surface of the groove processing roll 3. The method for manufacturing an externally grooved pipe according to claim 1, wherein the pipe is located between an extended surface in which the bases (groove bottoms) of the plurality of ridges 30 are continuous. 3. The diameter reducing roll 2 and the groove processing roll 3 are coaxially continuous or adjacent to each other, and the diameter of the diameter reduction roll 2 is formed on the outer peripheral surface of the groove processing roll 3. The outer diameter formed by the tops of the plurality of ridges 30 formed is larger than the diameter formed by the bases (groove bottoms) of the ridges 30.
4. The method for producing an externally grooved tube according to item 1.