JPS58173022A - Manufacture of tube having internal spiral rib - Google Patents

Abstract

PURPOSE:To obtain a titled high quality ribbed tube of high rib height ratio even in case of material difficult to work by manufacturing a metallic tube having a straight rib on inner face by hot extrusion, and twisting it in circumferential direction by tensile force smaller than the yield strength of the tube material. CONSTITUTION:In manufacturing a tube having intenal spiral rib used mainly for a heat transmitting tube, a hollow round heated metallic piece 5 coated with glass lubricant on inner and outer faces is put from the back into a container to which a die 2 is attached in the front. A stem 7 is put in from its back, and at the same time, a mandrel 8, which has a straight groove 9 on the outer peripheral face and moves axially in the stem 7, is inserted in the piece 5. Then, the stem 7 is advanced, and the material is pushed out between the hole of the die 2 and the mandrel 8, and a tube 10 having internal straight rib is obtained. One end and another end of the tube 10 are chucked by a heat stock 12 and a tail stock 13 respectively, and the tube 10 is twisted while a applying axial tensile force, and a tube having internal spiral rib is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a metal tube having spiral ribs on its inner surface (hereinafter referred to as a tube with inner spiral ribs), which is generally called a rifle tube.

This inner spiral ribbed tube, which is mainly used for heat transfer tubes such as boiler steam generation tubes, has conventionally been manufactured by cold drawing using a plug. To briefly explain the situation in the first drawing, a rotatable plug (1) with a spiral groove on the outer peripheral surface is coaxially installed in the hole mold of the die (2), and in this state, the die (2) is ), the plaque (1) is driven to rotate and a spiral rib (4) is formed on the inner surface of the tube. According to this method, the inner circumferential portion of the tube has the following characteristics: , :,′
7. In the case of so-called difficult-to-work materials such as high-alloy steel and stainless steel, which are subject to severe processing, seizing is likely to occur between the plug and the material, and the degree of processing must be moderated. 1+) is 2 of the tube thickness (1)
It is said that it cannot be made larger than 5%.

The larger the ratio of the rib height (01) to the tube thickness (1) (hereinafter referred to as rib height), the wider the surface inside the tube, and in the case of heat transfer tubes, the heat transfer efficiency increases. It is desirable to make it as large as possible because it will improve the product quality and increase the product value.

The present invention has responded to this demand by making it possible to maintain a large rib height (47g) and produce high-quality products even when paulownia wood is made of so-called difficult-to-process materials such as high alloy steel and stainless steel. The purpose of the present invention is to provide a manufacturing method for one tube with internal spiral ribs, and the time required for this is to manufacture a metal tube with straight ribs on the inside (hereinafter referred to as a tube with straight ribs on the inside) by hot extrusion. This tube is twisted in the circumferential direction to form a tube with internal spiral ribs.

In other words, instead of cold drawing, hot extrusion creates a tube by forcing heated material into an annular gap formed between the hole of the die and the mandrel. We are particularly good at manufacturing tubes made of difficult-to-work materials such as high-alloy steel and stainless steel, as well as irregularly shaped tubes. Therefore, according to this hot extrusion, even when the material is a so-called difficult-to-work material such as high alloy steel or stainless steel, an inner straight ribbed tube with a large rib height can be manufactured. and,
If twisting is applied to this tube with straight ribs on the inner surface, the straight ribbed tube (IJ) will be converted into a spiral rib at the same time as the tube is twisted, and the inner surface of the tube with straight ribs will be twisted without applying any harsh processing to the tube. is obtained, and the rib height is the same as that of the inner straight rib thin tube described above.

Therefore, according to the method of the present invention, the material is high alloy steel,
Even in the case of difficult-to-process materials such as stainless steel, high-quality internal spiral lip capillaries with large rib heights can be manufactured.

By the way, when the material is a difficult-to-work material such as high alloy steel or stainless steel, the lip height increase is limited to 25% using the conventional cold drawing method, but the method of the present invention reduces this to about 70%. This makes it possible to manufacture a pipe with internal spiral ribs of high quality, which is impossible to achieve using conventional methods.

Furthermore, according to the method of the present invention, an inner spiral ribbed tube with a high lip height can be easily manufactured with a high forging ratio, and also post-treatments such as appropriate heat treatment can be easily performed. The structure, especially the crystal grain size, can be adjusted to a required constant grain size, and creep resistance, etc. can be easily improved.

Hereinafter, the method of the present invention will be explained in more detail with reference to the drawings.

The method of the present invention includes the manufacturing process of an inward straight ribbed tube by hot extrusion as shown in FIG.
There are two steps as shown in b): the twisting step of the tube with nutrate ribs on the inner surface.

The manufacture of the tube with internal nutrate ribs is the same as the manufacture of tubes by ordinary hot extrusion, except that a mandrel (8) having straight grooves (9) on the outer circumferential surface is used.

That is, first, a hollow round heated metal piece (5) whose inner and outer surfaces are coated with Galanu lubricant is charged from the rear into a container (6) with a die (2) attached to the front. At the same time, the mandrel (8) moving in the axial direction inside the stem (7) is inserted into the metal piece (5).
). The outer circumferential surface of the mandrel (8) is provided with the straight grooves (9) as described above, and the number and cross-sectional shape of the grooves are determined according to the inner straight ribbed tube to be manufactured (inner spiral ribbed tube before twisting). The number and cross-sectional shape of the lips are the same.

As the metal piece (5), it is possible to use not only difficult-to-process materials such as high alloy steel and stainless steel, but also other steels, and even those that are subject to hot extrusion processing. Metals other than steel can also be used thermally.

Metal piece (5), stem (7) and mandre zv (8)
is set as described above, the stem (7) is advanced and the mold is formed between the hole of the die (2) and the mandrel/L/(8), as shown in Fig. 2(a). Extrude the material forward through the gap to create an inner straight lip bone canal H'e.

Once the inner straight ribbed tube (10) has been manufactured, the inner tube with nutrate ribs αoV?-is twisted in the direction of placement by a method similar to that shown in FIG. The method of manufacturing ribbed pipes (in Figure 2) utilizes a nutretcher, which was originally used for the purpose of adding twist to the pipe after pipe production to correct twists, bends, etc. of irregularly shaped pipes. It is.

The nutretcher consists of a headstock a2 which is connected to a hydraulic cylinder 01) to apply an axial tensile force to the material, and a tilter 1-tsk 0.0 which applies a circumferential torsional torque to the material.
1, one end of the tube αO with the inner nutrate lip is chucked with the head stock α, and the other end is chucked with the Tinutok 0 [with], so that the tube α0 with the inner nutrate lip is attached to the tube α0 in the tube axial direction. The pipe is twisted in the circumferential direction without applying any tensile force to produce a pipe with internal spiral ribs.

Inner Stray 1 to Rib Example At both ends of the tube Q1, in order to prevent the tube from idling during twisting, there are ribs shown in FIG. 3(a) (1).
), the fins αa are formed by welding overlay etc. on both ends.
It is preferable to provide .

The twisting of the inner straight ribbed tube may be performed cold, that is, after the tube has been cooled, warm, that is, while the tube is being cooled, or hot, that is, immediately after tube manufacturing or after reheating.
.

In addition, in order to make the torsion applied to the inner straight ribbed tube uniform in the tube axial direction and to improve the lip shape of the inner spiral ribbed tube, as shown in the method shown in Figure 2 (to), the tube is It is desirable to twist the tube while applying tensile stress. Needless to say, care must be taken so that this tensile stress does not exceed the yield strength in the processing temperature range of the pipe.

Next, an example of the present invention will be shown and its effects will be clarified.
A tube with straight ribs on the inside was manufactured.

The material of this pipe is 25Or-25Ni steel, and the dimensions are shown in Figure 4.Do-42,7 silk, d
, =82.85WW, dλ=28.11ff, 7.
= 6000 drunkenness.

Once the inner tube with nutrate lip is manufactured, it is next shown in Fig. 2 (
As shown in b), the tube was twisted 15 times in the circumferential direction while being pulled in the axial direction using a stretcher to produce a tube with an inner spiral rib having 8 rips and a twisting pitch of 1 rotation/400 Wll. The processing temperature was room temperature (10° C.), and the tensile stress was about 0.5% expressed as elastic strain.

The stretcher had a maximum tensile capacity of 100 tons for the headstock H, a maximum torque of 1500 HM for the head stock H, and a maximum torsional torque of 450 kg/m for the tail stock θ East.

The manufactured inner spiral rib capillary tube has virtually the same cross-sectional shape as the internal nutrate lipped tube manufactured in the previous step (see Figure 4), and its material is 25Or-25Ni nutrate lip, which is difficult to process. Despite being made of steel, a 46% increase in lip height was achieved. Incidentally, in the case of this material, the rib height could only be increased by 25% as described above using the conventional cold drawing method.

As described above, the present invention makes it possible to manufacture a tube with internal spiral ribs having a large height, which could not be manufactured by the conventional cold drawing method.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing the conventional method, Figure 2 (a) 0)l
3 is a cross-sectional view and a side view showing an example of the method of the present invention.
Figure (a) (to) is a side view and a front view showing the shape of the tube end in the method shown in FIG. In the figure, 2: die 7.5: metal piece, 6: container 7: stem, 8: mandrel, IO: inner straight ribbed tube,
12: Head nut tsuku, 13: Tail nu 1-tsuku. Applicant: Sumitomo Metal Industries Co., Ltd. Applicant: Idemitsu Sekiyu Ishigaku Co., Ltd., Representative Patent Attorney Izumi Katamoto Heavy voluntary procedure amendment 1. Indication of the case 3, Person making the amendment Relationship with the case Patent applicant address: 5-15-6 Kitahama, Higashi-ku, Osaka City Drawing 7 to be amended, Contents of the amendment (1) Figure 2 (a) of the drawing is attached as an attached document. I will correct it. Above Figure 2 (0) 5 Written amendment of voluntary procedure 1, Indication of the case Patent Application No. 54619 of 1982 2, Name of the invention Method for manufacturing internal spiral rigged pipe 3, Person making the amendment Relationship with the case Patent application Address 5-15 Kitahama, Higashi-ku, Osaka Name (21
1) Sumitomo Metal Industries, Ltd. Representative Norifumi Kumagai (and 1 other person) 4. Agent (Document sending date: Month, Day, 1939) 6. In the “Scope of Claims” column of the specification to be amended, Explanation" (Netherlands, "Brief Description of Drawings" column, Drawing 7, contents of amendments (11) Please refer to the appendix for the claims of the specification. (2) From page 3, line 2 of the above In line 3, it says, ``This tube is twisted in the circumferential direction...''
This is corrected by twisting the tube in the circumferential direction while applying a tensile force that is less than the lateral force of the tube material. (3) From line 18 to line 19 on page 5 of the same page, the phrase ``Other steel classes...'' was replaced with ``Other steel types...''
..." will be corrected. (4) From page 7, line 7 to line 8 of the same page [...
It is better to be able to fix it in the circumferential direction. ” and then add the following. ``In addition, a core metal may be inserted into the tube end to prevent tube buckling during chucking.'' (5) From page 7, line 14 to line 15 of the same page, ``Tube with internal spiral ribs'' In order to improve the lip shape of the pipe, "stop" is corrected to "in order to improve the lip shape of the pipe with internal spiral ribs, and to make the lip helical pitch and outside diameter of the pipe as uniform as possible in the pipe axis direction." . (6) On page 7, line 17 of the specification, it is desirable to perform twisting. ” was corrected to “perform the twisting process.” (7) Insert the following between page 7, line 19 and the last line of the same page. "After the twisting process, the internal spiral ribbed tube removed from the chuck 00 moe can be used as a product, or if necessary, the required length at both ends can be cut and removed." (8) Same as above, No. 8 In the ninth line of the page, the statement "Twist 15 times in the circumferential direction while pulling in the axial direction of the tube" is corrected to "Twist 15 times in the circumferential direction while applying a tensile force in the axial direction of the tube." (9) Insert the following between page 8, line 19 and the last line of the same page. [The outer diameter of the pipe in the axial direction and the torsion pitch puffiness of the inner spiral lip were 42.1 to 438 mm and 310 to 520 mm in the comparative example, which was twisted without applying any tensile force, and the puffiness was large and In extreme cases, only a undulating surface as shown in Fig. 5 could be obtained; As shown in the figure, a pipe with no undulating surface can be obtained.'' (Page 9, line 7 of the specification 10 states, ``...a pipe with a spiral rib on the same surface can be manufactured.'') It is corrected to ``...A tube with internal spiral ribs can be easily manufactured with high dimensional accuracy.'' αη Same as above, page 9, line 14, ``...This is an explanatory diagram of the cross-sectional shape. '' has been corrected as follows. ``...Explanatory diagram of the cross-sectional shape, Figure 5 shows the outside of the tube that occurs when the inner straight rib L1 is twisted without applying tensile force in the tube axis direction.'' This is an explanatory diagram showing a warm state.'' 02 Figure 5 of the drawing is supplemented as shown in the attached sheet. Above (Attachment) Claims (1) Manufacture of a metal tube having 7 tray trips on the inner surface by hot extrusion. After that, apply 1I of the tube material to the metal tube.
1. A method for manufacturing a tube with internal spiral ribs, which comprises twisting the tube in the circumferential direction while applying a tensile force equal to or less than the liJ force to produce a metal tube having spiral ribs on the inner surface.

Claims (1)

[Claims] (1) An inner surface characterized by manufacturing a metal tube having straight ribs on the inner surface by hot extrusion, and then twisting the metal tube in the circumferential direction to obtain a metal tube having spiral ribs on the inner surface. A method for manufacturing a spiral ribbed tube.