JPS60158916A - Manufacture of pipe with grooved inner surface - Google Patents

Abstract

PURPOSE:To manufacture efficiently a pipe with grooved inner surface free from abnormal fins by inserting a plug having a prescribed helix angle with respect to its axial direction, and a plug having a helix angle smaller than that of the former plug into a metallic pipe and pressing the pipe from its outer circumference by rolls. CONSTITUTION:In manufacturing a metallic pipe having plural grooves or projections in its inner surface by inserting plugs 1, 1' having prescribed grooves or projections 4, 4', which have helix angles with respect to their axial directions respectively in their outer circumferences into the metallic pipe 2, and pressing its outer circumference by rolling rolls 3, 3' which revolve in planetary motions around it while feeding it in the arrow-mark axial direction; the helix angle alpha2 of the groove or projection of plug 1' located in succession to the plug 1 is set to be smaller than the helix angle alpha1 of the plug 1 located at the 1st position mentioned above. In this way, the generation of the abnormally shaped fins of projection or groove formed in the inner surface of pipe 2 is prevented, the rolling speed is increased, and the product yield and the operating efficiency are improved.

Description

TECHNICAL FIELD This invention relates to a method of manufacturing a metal tube having an inner surface.

Prior Art A plug having grooves or protrusions on the outer periphery with a helix angle relative to the axial direction is inserted into a metal tube, and the outer periphery is compressed by a plurality of planetary-rotating rolls while feeding the metal tube in the axial direction. It is known in the art to form a plurality of grooves or protrusions on the inner surface of a metal tube by.

To explain specifically with reference to the drawings, FIG. 1 is a side view of the part where the material of the metal tube 2 is sandwiched between the plug 1 and one rolling roll 20, and FIG. FIG. 2 is a cross-sectional view of the entire device taken along line A-A. FIG. 3 is a partially enlarged sectional view showing the relationship between the plug and the material of the metal tube 2 being processed by the plug. FIG. 4 is a partially enlarged perspective view that does not show the state of the fins 5 on the inner surface of the metal tube formed on the plug.

Conventionally, as shown in FIGS. 1 and 2, a plug 1 having a protrusion 4 twisted at an angle α with respect to the axial direction on its outer periphery is inserted into a metal tube 2, and a plurality of plugs are inserted from the outside of the metal tube. When the metal tube 2 is fed as shown by the arrow in Fig. 1 while being compressed by the rolling roll 3, the material of the metal tube 2 is transferred to the rolling roll 3 and the plug 1.
By the protrusion 4 on the outer periphery of the plug 1, which is sandwiched between
As shown in FIG. 3, grooves are cut over the entire length of the metal tube material 2, and fin ridges 5 are formed between the grooves. In this conventional method, the torsion angle α of the protrusion 4 is constant over the entire length ρ of the plug 1.

However, with the conventional method, the fin crests 5 formed inside the metal tube often have abnormal shapes. Specifically, as shown in FIG.
This appeared as a crack 6 or a misaligned portion 7 of the fin crest as shown in FIG.

The reason for this is that the material of the metal tube 2 compressed by the plug 1 is plastically deformed by the rolling roll 3 and stretches in the length direction. Even though the feed rate at the end is higher, the torsion angle α of the protrusion 4 on the outer periphery of the plug 1 is constant, so lateral stress acts on the fin 111 on the inner surface of the metal tube. Met.

Purpose The purpose of the present invention is to improve the above-mentioned drawbacks of the conventional method and to provide a method for forming fins without irregularities in shape on the inner surface of a metal tube.

Structure The structure of the present invention is to insert a plug having a predetermined groove or protrusion on the outer periphery that has a helix angle with respect to the axial direction into a metal tube, and to move the outer periphery while feeding the metal tube in the axial direction. In a method of manufacturing a metal tube having a plurality of grooves or protrusions on the inner surface by pressing with a plurality of planetary rotating rolls, the groove or the groove on the outer periphery of the plug in the initial position where the outer periphery of the metal tube is pressed by the rolls. This method of manufacturing an internally grooved tube is characterized by using a plug whose torsion angle at a position subsequent to the protrusion is smaller than the above-mentioned torsion angle of the protrusion.

The above structure of this invention will be specifically explained with reference to the drawings. FIGS. 5 to 7 each show a specific embodiment of this invention, and similarly to FIG. 1, a plug and one rolling roll are used. FIG. 2 is a side view of a portion of the metal tube with material 2 sandwiched therebetween.

Figure 5 shows that a plug 1 with a large helix angle α1 and a plug 1' with a small helix angle α2 of the protrusion 4 on the outer circumference of the plug are installed apart from each other, and rolled D-rules 3 and 3' are assembled separately to each plug. Give an example.

FIG. 6 shows an example in which a plug 1 with a large helix angle α1 of the protrusion 4 on the outer periphery and a plug 1' with a small helix angle α2 are in close contact with each other, and a wide rolling roll 3 is combined with them.

FIG. 7 shows the torsion angle α of the protrusion 4 in one plug.
This is an example in which a wide rolling roll 3 is combined with a roll having a large blind portion and a small twist angle α2 portion.

In all of these specific examples, the torsion angle of the protrusion 4 on the outer periphery of the plug is divided into two stages, but these may be divided into three or more stages, and the rolling roll may also be divided into three or more parts. good.

The relationship between the torsion angles α1 and α2 of the protrusions on the outer periphery of the plug of the present invention shown in the above drawings can be determined from the difference in elongation of the material between the initial stage of processing and the latter stage of processing, as explained above.

The numerical values will be specifically explained below using examples.

As an example product, the outer diameter is 12.7 cm and the bottom wall thickness is 0.700 Il.
l.

When making an internally grooved metal tube with a fin ridge height of 0.30 cm, a number of threads of 60, and a fin helix angle of 25°, use plug protrusions 4 with helix angles α1 = 26° and α2 = 25°. It was rolled.

The product fins had a clean appearance with no cracks or deviations.

effect The method of this invention provides the following effects.

1. No abnormalities in the shape of the fins occur when manufacturing pipes with internal grooves.

2. Since abnormalities in the shape of the fins do not appear, it is possible to increase the speed of rolling and polishing.

3. For the same reason, yield and operation rate can be expected to improve.

4゜Production efficiency improves.

[Brief explanation of drawings]

FIG. 1 is a partial side view of the apparatus used in the method of the present invention, FIG. 2 is an overall sectional view taken along line A-A in FIG. 1, and FIG. 3 is a plug and a metal tube material being processed. FIG. 4 is a partial enlarged sectional view taken along line A-A showing the relationship between the fins and the abnormal state of the fin. FIG. 4 is a partially enlarged view showing another example of the abnormal state. FIG. 5 is a device used in the present invention. FIG. 6 is a partial side view showing another specific example of the device used in this invention, and FIG. 7 is a partial side view showing another specific example of the device used in this invention. FIG. 1 and 1'...Plug, 2...Metal tube, 3...
Roll) 4 and 4--protrusion, 5-fin crest, 6-crack, 7-misaligned portion. α, α1, α2... Torsion angle of protrusion 4.4-Patent applicant Sumitomo Light Metal Industries Co., Ltd. Agent Patent attorney Hidetaka Komatsu Patent attorney Kosai Asahi Figure 5 Figure 26 Procedure details... Original document (spontaneous) February 22, 1980 Kazuo Wakasugi, Commissioner of the Japan Patent Office 1. Indication of the case 1988 Patent Application No. 013320@Relationship with the case Patent applicant name (227) Sumitomo Light Metal Industries, Ltd. 5. Date of amendment order. 6. Detailed explanation of the invention in the statement of subject matter of the amendment. 7. Contents of the amendment As shown in the attached sheet. (Attachment) (1) Correct “Roll Roll 2” in Line 10 of Page 2 of Specification M to “Roll Roll 3.” (2) Lines 13 to 15 [Figure 3 shows 81. . Figure 4 shows 00. ] is corrected to "36. for Figures 3 and 4." (3) Correct “Figure 3” on page 3, line 13 to “Figure 4.”

Claims (1)

[Claims] A plug with a predetermined groove or protrusion on the outer periphery that has a helix angle with respect to the axial direction is inserted into a metal tube, and the outer periphery is compressed by a plurality of planetary rotating rolls while feeding the metal tube in the axial direction. In the method of manufacturing a metal tube having a plurality of grooves or protrusions on the inner surface, the outer circumference of the metal tube is compressed by a roll. III. Method for manufacturing an internally grooved pipe characterized by using a plug in which the helix angle is small at the position of