JPH1119711A - Method for working tube with groove on its inside surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a working method of a tube with grooves on its inside surface for executing stable forming without affecting on the groove shape even when wear is generated on the surface of a grooving plug. SOLUTION: A tube stock 8 which is fed from the tube feeding side is reduced with a floating plug 2 and holding die 1. A motor 9 is rotated while being gradually moved toward the tube drawing side and rolling balls 5 which are housed in a working ring 21 arranged on the outside surface of the tube are rotated in the circumferential direction of the tube while gradually continuously or intermittently moving for the drawing side of the tube. At this time, the grooving plug 3 is rotated with the grooves carved on the peripheral surface of the grooving plug 3 by drawing the tube. In such a way, the diameter of the reduced tube stock 8 is further reduced by pressing the tube stock 8 against the grooving plug 3 with the rolling balls 5 and also spiral-shaped fins 6 which match the grooves of the grooving plug 3 are transferred on the inside surface of the tube. Furthermore, the diameter of this tube stock 8 on the inside surface of which the fins 6 are formed is reduced with a finishing die 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for processing an internally grooved tube used in an air-cooled heat exchanger such as an air conditioner for home and business use, and more particularly, to a method for processing a long tube having a length of several thousand meters. The present invention relates to a method for processing an inner grooved tube capable of forming fins having a uniform height on the inner surface of the tube.

[0002]

2. Description of the Related Art As a condenser and an evaporator of an air-cooled heat exchanger, a tube having an inner surface groove is used in which a spiral groove is formed on the inner surface of the tube to improve heat transfer efficiency. FIG. 2 is a schematic cross-sectional view in the pipe axis direction showing a conventional processing device for an internally grooved pipe (JP-A-63-309321). In the conventional method of processing a tube with an inner groove, the floating plug 12 is inserted inside the raw tube 18. The floating plug 12 has a substantially frustoconical shape in which the outside diameter on the tube supply side is slightly smaller than the inside diameter of the raw tube 18 and the outside diameter on the tube withdrawal side is smaller than that on the tube supply side. This floating plug 12
A holding die 1 for reducing the diameter of the raw tube 18 together with the floating plug 12 is provided on the outer surface of the raw tube 18 at a position matching with the holding die 1.
1 is arranged. In addition, the floating plug 12
Is connected to a substantially cylindrical grooved plug 13 via a connecting shaft 14. A pipe 18 is provided on the peripheral surface of the grooved plug 13.
A groove having a shape to be formed is formed on the inner peripheral surface. Further, the grooved plug 13 can freely rotate about the connecting shaft 14 as an axis. A plurality of rolling balls 15 are arranged on the outer surface of the base tube 18 at a position matching the grooved plug 13 in the circumferential direction of the tube. The rolling balls 15 are housed in a processing ring 31 and arranged at an appropriate distance from each other, and the rolling balls 15 are held at predetermined positions in the tube axis direction by the processing rings 31. The processing ring 31 is connected to a drive shaft 32 of the motor 19. The motor 19 has a cylindrical drive shaft 32 and a coil 33 for rotating the drive shaft 32 by a magnetic field. The power is supplied to the coil 33 so that the drive shaft 32 is driven to rotate. And rotationally driven. The base tube 18 passes through the center of the motor 19. Thereby, the rolling ball 15 rotates in the pipe circumferential direction about the pipe axis. On the downstream side of the rolling ball 15 in the tube drawing direction, a finishing die 17 for contracting the outer diameter of the tube 18 having a fin formed on the inner surface to a predetermined size is provided in contact with the tube 18. I have.

[0003] A conventional processing method using the apparatus for processing an inner grooved pipe configured as described above is as follows. Before the start of processing, the floating plug 12 is
It is held by a mechanical or magnetic means at a position closer to the tube supply side than one. Then, supply of the raw tube 18 is started from this state, and thereafter, the holding of the floating plug 12 is released, and the floating plug 12 moves to a position where it is aligned with the holding die 11 with the movement of the raw tube 18. Then, the raw tube 18 is subjected to a contraction process by the floating plug 12 and the holding die 11. Next, the reduced tube 18 is compressed by a rolling ball 15 and is subjected to a rolling force by the rolling ball 15 to a grooved plug 13 arranged inside the tube 18. Pressed. The grooved plug 13 is connected to the floating plug 12 via a connection shaft 14, and the floating plug 12 is positioned at a position where the floating plug 12 is aligned with the holding die 11 by the frictional force caused by pulling out the base tube 18 and the drag force from the holding die 11. And the grooved plug 13 is also fixed to the rolling ball 1
It stops at the position matching 5. Therefore, when the rolling ball 15 is brought into contact with the outer peripheral surface of the base tube 18 and is driven to rotate in the circumferential direction, the base member 18 cooperates with the grooved plug 13.
Fins 16 are formed on the inner peripheral surface of the fin. At this time, the grooved plug 13 is rotated by the groove formed on the peripheral surface of the grooved plug 13 by pulling out the tube. Further, the base tube 18 having the fins 16 formed on its inner surface is subjected to a contraction process by a finishing die 17 to produce an inner grooved tube having a desired outer diameter.

[0004] According to this conventional technique, the grooved plug 13 can be easily moved to the pipe drawing side, and breakage of the pipe at the start of machining can be prevented. As in the prior art, there has been proposed a means for easily moving the grooved plug 13 to prevent the tube from being broken (Japanese Patent Application Laid-Open No. 63-1988).
309322). In this prior art, means for directly holding the grooved plug magnetically by an electromagnet is provided, and the grooved plug is moved by turning on / off the electromagnet.

[0005]

However, when an inner grooved tube is machined by these conventional techniques, if the length of the blank tube to be machined is as long as several thousand meters, even if a super hard material is used as a grooved plug. Even if used, the surface of the grooved plug will wear. This is particularly noticeable with high fin shapes. For this reason, when rolling is continuously performed, there is a problem that, for example, a problem such as a fin height being sequentially reduced occurs.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has an inner grooved pipe capable of performing stable molding without affecting the groove shape even if abrasion occurs on the grooved plug surface. An object of the present invention is to provide a processing method.

[0007]

According to the present invention, there is provided a method of processing an inner grooved pipe according to the present invention. A grooved plug that is relatively rotatably connected to the floating plug via a connection shaft is arranged, and the floating plug is engaged with the holding die to move the grooved plug to the rolling ball arrangement position. Positioning, by pressing the raw tube against the grooved plug with the rolling ball, the groove shape of the grooved plug is transferred to the inner surface of the raw tube. The processing ring to be accommodated is driven to rotate by the rotation of the motor, and the rolling ball rotates in the circumferential direction of the raw tube, thereby continuously or intermittently processing the fin on the inner surface of the tube. Characterized by moving the compacting ball by moving the drive shaft of the motor or motors in the tube axis direction to the tube axis direction of the mother tube.

In the present invention, a compaction ball located outside the raw tube with respect to the grooved plug is housed, and a motor or a drive shaft of the motor connected to the processing ring is gradually moved in the tube axis direction. Since the fins are machined on the inner surface of the raw tube while moving, the portion of the grooved plug that corresponds to the rolling ball also gradually moves in the tube axis direction. For this reason, since the pressing portion of the rolling ball always moves to the unworn portion of the grooved plug, the groove shape of the grooved plug does not change due to wear, and local wear on the surface of the grooved plug is reduced. . Further, an inner grooved tube having fins of uniform height formed on the inner surface is obtained.

[0009] It is preferable that the moving distance of the rolling ball is 0.15 mm or more per 1 km of the length of the raw tube after processing.

When the moving distance of the rolling ball is 0.15 mm or more per 1 km of the length of the raw tube, the wear of the surface of the grooved plug is further reduced, and the longitudinal length of the fin height of the internally grooved tube is reduced. Fluctuations in the direction can be effectively suppressed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The method of the embodiment of the present invention will be specifically described below with reference to the accompanying drawings. FIG. 1 is a schematic cross-sectional view in the pipe axis direction showing an internal grooved pipe processing apparatus used in the method of the embodiment of the present invention. The processing apparatus for the internally grooved pipe used in the method of the present embodiment is the same as the conventional processing apparatus shown in FIG. 2 except that the motor 9 can move in the pipe axis direction. , A grooved plug, a holding die, a compacted ball, a motor and a finishing die are provided in the same positional relationship as in FIG. That is, the floating plug 2 having a substantially truncated cone shape is inserted into the inside of the raw tube 8, and the outer surface of the raw tube 8 at a position matching the floating plug 2 is subjected to diameter reduction processing together with the floating plug 2. Holding dies 1 are arranged. The floating plug 2 has a connecting shaft 4
Grooved plug 3 in which a groove is formed in a substantially cylindrical peripheral surface through
Are connected. Further, the grooved plug 3 is connected to the connecting shaft 4.
Can be freely rotated around the axis. A plurality of rolling balls 5 are arranged on the outer surface of the raw tube 8 at a position matching the grooved plug 3. This rolling ball 5
Is stored in the processing ring 21 and the processing ring 2
1 is connected to the drive shaft 22 of the motor 9. And
When the drive shaft 22 is rotated by the coil 23 of the motor 9, the processing ring 21 is rotationally driven in the pipe circumferential direction.
For this reason, the rolling ball 5 can rotate in the pipe circumferential direction about the pipe axis. A finishing die 7 for reducing the outer diameter of the base tube 8 to a predetermined size is provided in contact with the inner grooved tube on the tube drawing side separated from the rolling ball 5 by a predetermined length. I have.

The apparatus used in the method of this embodiment is different from the conventional apparatus in that the motor 9 arranged on the outer surface of the tube is gradually moved to the tube withdrawal side as shown in FIG. It is possible. Thereby, the compacted ball 5 can be gradually moved to the pipe drawing side. This movement may be performed continuously or intermittently in the groove processing step. The movement in the tube axis direction may be on the tube drawing side or in the opposite direction.

In the method of the present embodiment, the raw pipe 8 supplied from the pipe supply side to the processing apparatus is subjected to the contraction by the floating plug 2 and the holding die 1. And the motor 9
Is rotated while gradually moving it toward the pipe drawing side, and is rotated in the circumferential direction of the pipe while gradually or intermittently gradually moving the compacted balls 5 arranged on the outer surface of the pipe and housed in the processing ring toward the pipe drawing side. Let it. At this time, the grooved plug 3 is rotated by the groove formed on the peripheral surface of the grooved plug 3 by pulling out the tube. By pressing the reduced tube 8 against the grooved plug 3 by the rolling ball 5, the diameter of the tube 8 is further reduced, and a spiral shape matching the groove of the grooved plug 3 is formed on the inner surface of the tube. Is transferred. Then, the inner tube 8 having the fins 6 formed on its inner surface is reduced in diameter by a finishing die 7 to complete an inner grooved tube.

As described above, in the method of the present embodiment, since the raw tube 8 is processed while the rolling ball 5 is gradually moved to the tube drawing side by moving the motor 9, the grooved plug 3 is processed. The portion pressed from the rolling ball 5 via the raw tube 8 also gradually moves. For this reason, the wear of the surface of the same location of the grooved plug 3 is reduced.

In the method of this embodiment, the motor 9
Was moved to the tube drawing side, but the driving shaft of the motor 9 was moved in the tube axis direction by using the axial extension due to the heat generated by machining, etc. 5 can also be moved in the tube axis direction.

The method of moving the motor or its drive shaft is not particularly limited. It can be moved by a mechanical method, an electric method, or the like.

The moving distance of the rolling ball is preferably not less than 0.15 mm per 1 km of the length of the raw tube. When the moving distance is less than 0.15 mm per km, the effect of reducing the wear of the grooved plug surface is small, and
The height of the fin tends to fluctuate in the longitudinal direction of the raw tube.
For this reason, the heat transfer performance and the secondary workability of the inner grooved tube due to the dimensional change deteriorate. Therefore, it is desirable that the moving distance of the rolling ball be 0.15 mm or more per 1 km after the processing of the raw tube.

[0018]

As described above, according to the present invention,
Since grooves are machined on the inner surface of the raw tube while moving the rolling ball in the tube axis direction, wear of the grooved plug surface is reduced, and an inner grooved tube having uniformly high fins in the longitudinal direction is manufactured. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view in the pipe axis direction showing an apparatus for processing an inner grooved pipe used in a method according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view in the pipe axis direction showing a conventional processing device for an internally grooved pipe.

[Explanation of symbols]

 1, 11; holding dies 2, 12; floating plugs 3, 13; grooved plugs 4, 14; connecting shafts 5, 15; rolling balls 6, 16; fins 7, 17; finishing dies 8, 18; , 19; motors 21, 31; processing rings 22, 32; drive shafts 23, 33;

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FIF28F 1/40 F28F 1/40 D (72) Inventor Kiyonori Koseki 65, Hirasawa, Hadano-shi, Kanagawa Prefecture Kobe Steel, Ltd. Hadano Plant (72) Invention Person Tetsuo Uchida 65, Hirasawa, Hadano City, Kanagawa Prefecture, Kobe Steel Works, Hadano Plant

Claims (3)

[Claims] 1. A raw pipe is sequentially reduced in diameter by a holding die and a plurality of rolling balls, and a floating plug is connected to the floating pipe in the raw pipe via a connection shaft so as to be relatively rotatable. A grooved plug is arranged, the floating plug is engaged with the holding die, the grooved plug is located at the position where the rolling ball is provided, and the raw tube is pressed against the grooved plug by the rolling ball. In the method of processing an inner grooved tube for transferring the groove shape of the grooved plug onto the inner surface of the raw tube, a processing ring for accommodating the rolling ball is rotationally driven by rotation of a motor to rotate the rolling ball. Is rotated in the circumferential direction of the tube, whereby the motor is continuously or intermittently moved in the tube axis direction while processing fins on the inner surface of the tube. A method for processing an inner grooved pipe, wherein a pressure ball is moved in a pipe axis direction of the raw pipe. 2. The raw tube is sequentially reduced in diameter by a holding die and a plurality of rolling balls, and a floating plug is connected to the raw tube via a connecting shaft so as to be relatively rotatable. A grooved plug is arranged, the floating plug is engaged with the holding die, the grooved plug is located at the position where the rolling ball is provided, and the raw tube is pressed against the grooved plug by the rolling ball. In the method of processing an inner grooved tube for transferring the groove shape of the grooved plug onto the inner surface of the raw tube, a processing ring for accommodating the rolling ball is rotationally driven by rotation of a motor to rotate the rolling ball. Is rotated in the circumferential direction of the pipe, whereby the drive shaft of the motor is continuously or intermittently moved in the pipe axis direction while processing fins on the pipe inner surface. And moving the compacted ball in the tube axis direction of the raw tube. 3. The processing of an inner grooved pipe according to claim 1, wherein a moving distance of the rolling ball is 0.15 mm or more per 1 km of a length of the raw pipe after processing. Method.