JP3747302B2 - Internal grooved tube processing method - Google Patents

Description

【００２１】
次に、加工後の長さが５ｋｍとなったときに加工を終了し、内面溝付管の加工末期のフィン高さを測定した。そして、加工初期のフィン高さとの変化量を求めた。この結果を表２に示す。
【００２２】
【表２】

【００２３】
表２に示すように、実施例３乃至７並びに参考例１及び２においては、保持ダイスを徐々に移動させながら加工を行っているので、フィン高さの変化量が小さい。特に、実施例３乃至７においては、移動距離が０．１５ｍｍ以上であるので、その効果が大きい。
【００２４】
一方、比較例８においては、保持ダイスを移動させずに加工を行っているので、フィン高さの変化量が大きい。
【００２５】
【発明の効果】
以上説明したように、本発明によれば、溝付プラグに連結されたフローティングプラグを保持する保持ダイスを移動させながら素管の内面に溝を加工するので、溝付プラグ表面の摩耗を低減し、長手方向に一様に高いフィンを有する内面溝付管を製造することができる。
【図面の簡単な説明】
【図１】本発明の実施例に係る内面溝付管の加工装置を示す管軸方向の断面図である。
【図２】従来の内面溝付管の加工装置を示す管軸方向の断面図である。
【符号の説明】
１、１１；保持ダイス
２、１２；フローティングプラグ
３、１３；溝付プラグ
４、１４；連結軸
５、１５；転圧ボール
６、１６；フィン
７、１７；仕上げダイス
８、１８；素管[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for processing an internally grooved tube used in air-cooled heat exchangers such as domestic and commercial air conditioners, and in particular, a uniform high on the tube inner surface over the entire length of a long tube of several thousand meters. The present invention relates to a method of processing an internally grooved tube that can form a fin.
[0002]
[Prior art]
The condenser of the air-cooled heat exchanger uses an internally grooved tube in which a spiral groove is formed on the tube inner surface to improve heat transfer efficiency. FIG. 2 is a sectional view in the tube axis direction showing a conventional processing apparatus for internally grooved tubes (Japanese Patent Laid-Open No. 63-309321). In the conventional method for processing an internally grooved tube, a floating plug 12 is inserted into the inside of the raw tube 18. The floating plug 12 has a substantially truncated cone shape whose outer diameter on the pipe supply side is slightly smaller than the inner diameter of the raw pipe 18 and whose outer diameter on the pipe drawing side is smaller than that on the pipe supply side. A holding die 11 for reducing the diameter of the raw tube 18 together with the floating plug 12 is disposed on the outer surface of the raw tube 18 at a position aligned with the floating plug 12. A substantially cylindrical grooved plug 13 is connected to the floating plug 12 via a connecting shaft 14. A groove having a shape to be formed on the inner peripheral surface of the raw tube 18 is processed on the peripheral surface of the grooved plug 13. Further, the grooved plug 13 can freely rotate about the connecting shaft 14. A plurality of rolling balls 15 are arranged on the outer surface of the raw pipe 18 at a position aligned with the grooved plug 13 so as to be rotatable in the pipe circumferential direction about the pipe axis. Further, on the downstream side of the rolling ball 15 in the tube drawing direction, a finishing die 17 for reducing the outer diameter of the raw tube 3 having fins formed on the inner surface to a predetermined size is provided in contact with the raw tube 18. Yes.
[0003]
A conventional processing method using the processing device for an internally grooved tube configured as described above is as follows. Before starting the processing, the floating plug 12 is held by mechanical or magnetic means closer to the tube supply side than the holding die 11. Then, the supply of the raw tube 18 is started from this state, and then the holding of the floating plug 12 is released, and the floating plug 12 moves to a position aligned with the holding die 11 as the raw tube 18 moves. The base tube 18 is reduced in size by the floating plug 12 and the holding die 11. Next, the tube 18 subjected to the tube contraction is contracted by the rolling ball 15, and the grooved plug 13 disposed inside the tube 18 is subjected to the rolling force by the rolling ball 15. Pressed. The grooved plug 13 is connected to the floating plug 12 via a connecting shaft 14, and the floating plug 12 is aligned with the holding die 11 by the frictional force generated by pulling out the raw tube 18 and the drag from the holding die 11. Therefore, the grooved plug 13 also stops at a position where it is aligned with the rolling ball 15. Accordingly, when the rolling ball 15 is brought into rolling contact with the outer peripheral surface of the base tube 18 and rotationally driven in the circumferential direction, the fins 16 are formed on the inner peripheral surface of the base tube 18 by the cooperative action with the grooved plug 13. . At this time, the grooved plug 13 is rotated by a groove carved in the peripheral surface of the grooved plug 13 by pulling out the tube. Further, the raw tube 18 having the fins 16 formed on the inner surface thereof is subjected to contraction processing by a finishing die 17 to produce an inner grooved tube having a desired outer diameter.
[0004]
According to this prior art, the grooved plug 13 can be easily moved to the tube drawing side, and the breakage of the tube at the start of processing can be prevented. Similarly to this prior art, means for easily moving the grooved plug 13 to prevent the tube from breaking has been proposed (Japanese Patent Laid-Open No. 63-309322). In this prior art, means for directly holding a grooved plug by an electromagnet is provided, and the grooved plug is moved by turning on and off the electromagnet.
[0005]
[Problems to be solved by the invention]
However, when the inner grooved tube is machined by these conventional techniques, when the length of the machined tube is as long as several thousand meters, even if a cemented carbide is used as the grooved plug, The surface is worn. This is particularly noticeable with high fin shapes. For this reason, when rolling continuously, there exists a problem that malfunctions, such as a fin height becoming low, generate | occur | produce, for example.
[0006]
The present invention has been made in view of such a problem, and even if wear occurs on the grooved plug surface, the inner grooved tube processing method can be stably formed without affecting the groove shape. The purpose is to provide.
[0007]
[Means for Solving the Problems]
The inner grooved pipe processing method according to the present invention is such that the raw pipe is successively reduced in diameter by a holding die and a plurality of rolling balls, and a floating plug is connected to the floating pipe via a connecting shaft. A grooved plug connected rotatably, and the floating plug is engaged with the holding die so that the grooved plug is positioned at the position where the rolling ball is disposed. In the processing method of the inner surface grooved tube for transferring the groove shape of the grooved plug to the inner surface of the raw tube by pressing the tube against the grooved plug, continuously or intermittently while performing the groove processing, The holding die is moved in the tube axis direction of the raw tube.
[0008]
In the present invention, the fin is processed on the inner surface of the raw tube while gradually moving the holding die for holding the floating plug connected to the grooved plug, so that the portion corresponding to the rolling ball of the grooved plug also moves gradually. . For this reason, the unworn portion of the grooved plug is always fed into the inferior portion of the rolling ball, so that the groove shape does not change due to wear, and local wear on the grooved plug surface is reduced. Furthermore, an internally grooved tube having a fin of uniform height formed on the inner surface is obtained.
[0009]
In addition, it is desirable to move the holding die so that the moving distance of the holding die is 0.15 mm or more per 1 km processed length of the raw tube.
[0010]
When the moving distance of the holding die is 0.15 mm or more per 1 km processed length of the raw tube, the wear of the grooved plug surface is further reduced, and the fin height of the inner grooved tube is changed in the longitudinal direction. It can be effectively suppressed.
[0011]
[Means for Solving the Problems]
The inner grooved tube processing method according to the present invention includes a floating plug and a grooved plug connected to the floating plug via a connecting shaft so as to be relatively rotatable with each other, and the outside of the tube is moved outside the tube. A holding die that engages with the floating plug is disposed through the raw tube, a plurality of rolling balls are disposed at positions that align with the grooved plug, and the raw tube is pulled out to thereby remove the raw tube. with successively reduced in diameter by the holding die and the compaction ball, a base tube is pressed into the grooved plug continuously transferring the groove shape of the grooved plug on the inner surface of the blank tube by the compacting ball In the inner grooved tube processing method, the groove is processed continuously or intermittently while the holding die is moved in the tube axis direction of the raw tube, and the moving distance of the holding die is processed. Length and wherein the moving 0. As a 15mm or more per km.
[0012]
The method of this embodiment is different from the conventional method in that the holding die 1 arranged on the outer surface of the pipe is gradually moved in the pipe axis direction as shown in FIG. This movement may be moved continuously or intermittently in the groove processing step.
[0013]
In this embodiment, the raw tube 8 supplied to the processing apparatus from the tube supply side is subjected to tube contraction processing by the floating plug 2 and the holding die 1 while the holding die 1 is gradually moved to the tube drawing side. And the rolling ball 5 arrange | positioned on the pipe outer surface is rotated. At this time, the grooved plug 3 is rotated by a groove carved in the peripheral surface of the grooved plug 3 by pulling out the tube. In this way, by pressing the tube 8 that has been subjected to the tube contraction against the grooved plug 3 by the rolling ball 5, the tube 8 is further reduced in diameter, and the inner surface of the tube is spirally aligned with the groove of the grooved plug 3 The fin 6 is transferred. Then, the inner tube with the fins 6 formed on the inner surface is subjected to diameter reduction processing with a finishing die 7 to complete the inner grooved tube.
[0014]
As described above, in this embodiment, since the raw tube 8 is processed while the holding die 1 is gradually moved to the tube drawing side, the rolling ball 5 of the grooved plug 3 passes through the raw tube 8. The pressed part also moves gradually. For this reason, it is reduced that the surface of the same location of the grooved plug 3 is worn.
[0015]
The moving distance of the holding die is preferably 0.15 mm or more per 1 km length of the raw tube after processing. When the moving distance is less than 0.15 mm per 1 km, wear of the grooved plug surface increases, and the height of the fin may vary in the longitudinal direction of the raw tube. For this reason, the secondary workability etc. which originate in the heat-transfer performance and dimensional change of an internally grooved pipe | tube deteriorate. Therefore, it is desirable that the moving distance of the holding die is 0.15 mm or more per 1 km after the processing of the raw tube.
[0016]
Moreover, the moving method of the holding die is not particularly limited. It can be moved by a mechanical method or an electrical method.
[0017]
Furthermore, as long as the moving direction of the holding die is in the tube axis direction, either the upstream side or the downstream side may be used.
[0018]
【Example】
Next, examples of the present invention will be described in comparison with comparative examples that depart from the scope of the claims.
[0019]
First, fins were processed on the inner surface of the raw tube at the speeds of Examples 3 to 7, Reference Examples 1 and 2 and Comparative Example 8 shown in Table 1. At this time, the fin height at the initial stage of machining was measured at the start of machining.
[0020]
[Table 1]

[0021]
Next, when the length after processing reached 5 km, the processing was terminated, and the fin height at the end of processing of the internally grooved tube was measured. And the variation | change_quantity with the fin height at the initial stage of a process was calculated | required. The results are shown in Table 2.
[0022]
[Table 2]

[0023]
As shown in Table 2, in Examples 3 to 7 and Reference Examples 1 and 2 , processing is performed while gradually moving the holding die, so that the amount of change in fin height is small. In particular, in Examples 3 to 7, since the moving distance is 0.15 mm or more, the effect is great.
[0024]
On the other hand, in Comparative Example 8, since the processing is performed without moving the holding die, the amount of change in the fin height is large.
[0025]
【The invention's effect】
As described above, according to the present invention, since the groove is processed on the inner surface of the raw tube while moving the holding die for holding the floating plug connected to the grooved plug, the wear on the surface of the grooved plug is reduced. An internally grooved tube having uniformly high fins in the longitudinal direction can be produced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view in the tube axis direction showing an apparatus for processing an internally grooved tube according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view in the tube axis direction showing a conventional processing apparatus for internally grooved tubes.
[Explanation of symbols]
1 and 11; holding dies 2 and 12; floating plugs 3 and 13; grooved plugs 4 and 14; connecting shafts 5 and 15; rolling balls 6 and 16; fins 7 and 17;

Claims (1)

A floating plug and a grooved plug connected to the floating plug through a connecting shaft so as to be relatively rotatable are arranged in the raw pipe, and the outer pipe is held to engage with the floating plug through the raw pipe. with placing the die, a plurality of compaction ball disposed at a position aligned with the grooved plug, by pulling the blank tube, sequentially reduced in diameter by the holding die and the compaction ball the mother tube together with, in the compaction processing method inner grooved tube a base tube is pressed into the grooved plug continuously transferring the groove shape of the grooved plug on the inner surface of the blank tube by a ball performs a grooving while, continuously or intermittently, the holding die in the tube axis direction of the mother tube, the moving distance of the holding die, serving as the working length 1km per 0 of blank tube. 15 mm or more Method of processing an inner grooved tube and moving in one direction.

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