JPH09136103A - Outer fin fin tube, manufacturing method thereof and roll die used in the manufacturing method - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To form a seamless stainless steel pipe having fins, which has excellent strength and toughness which cannot be obtained by extrusion. Serving dice. SOLUTION: The shape of the caliber 3 of the reduced diameter portion 6 of the roll die 1 of the cold pilger mill shown in FIG. 1 is made into a perfect circular arc shape over the entire reduced diameter portion 6, and the upper and lower roll dies 1 and 1 are milled. In the set state, the depth from the mandrel shaft center is larger than the caliber width on the large caliber diameter side, and the depth from the mandrel shaft center is smaller on the smaller caliber diameter side than the caliber width. Also, the roll die is arranged so that the gap 9 on the caliber side between the shoulders of the upper and lower roll dies has a constant fin size and thickness in all areas of the reduced diameter portion, and the stainless steel material pipe is extended only by feeding without rotating. It is thinned and rolled to manufacture a stainless steel pipe with fins on the outer surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a finned pipe made of metal, and particularly to a long finned pipe made of stainless steel.

[0002]

2. Description of the Related Art Conventionally, a long finned tube is manufactured by extruding a metal material with a die. The material of such finned tube is generally an aluminum alloy that can be easily extruded, and the finned tube made of aluminum alloy produced by such extrusion is used for applications such as heat exchangers. However, an aluminum alloy material may not be satisfactory for a member requiring high strength, and a finned tube made of a material having high strength such as steel is required. Fins of seamless steel pipe made of stainless steel are required for use under various harsh conditions. However, it is not easy to manufacture finned tubes such as steel by extrusion. That is, since it is hot extrusion, there is a problem in dimensional accuracy, and cold drawing is required. by the way,
Seamless stainless steel pipe is manufactured by cold pilger rolling. However, there has been no finned tube of seamless stainless steel tube manufactured by cold pilger rolling.

[0003]

SUMMARY OF THE INVENTION The problem to be solved by the present invention is to provide a finned pipe of seamless stainless steel pipe by cold pilger rolling which could not be manufactured conventionally, and to provide a manufacturing method thereof. And to provide a roll die for use in the manufacturing method.

[0004]

According to the present invention for solving the above-mentioned problems, in the invention of claim 1, the material pipe is non-rotatably fed in the cold pilger rolling, and fins are erected on both sides of the outer surface of the stretched pipe. This is a tube with fins on the outer surface.

According to the second aspect of the present invention, the caliber shape of the reduced diameter portion of the roll die for cold pilger rolling is a perfect circular arc shape over the entire area of the reduced diameter portion, and the caliber diameter of the upper and lower roll dies is in a mill set state. When the rolling start of most part is 1.0 section (hereinafter referred to as “sec”) and the rolling end on the small diameter side is 0.0 sec, 1.0 se of the rolling start is set.
On the c side, the depth from the mandrel axis is increased compared to the caliber width, and the depth from the mandrel axis is gradually increased compared to the caliber width as the caliber diameter increases from the large caliber diameter side. To the end of rolling, which is the smallest diameter part of the caliber.
At 0 sec, the depth from the mandrel shaft center is made equal to the caliber width, and the gap between the caliber sides between the upper and lower roll die shoulders is made to have a constant fin size thickness in all areas of the reduced diameter portion. A method of manufacturing a pipe with fins, characterized in that a roll die is arranged, and the material pipe is stretched and thinned only by feeding it without rotating it, and is rolled.

According to the third aspect of the invention, the caliber shape of the reduced diameter portion, which is the hole type of the upper and lower roll dies, is a perfect circular arc shape over the entire reduced diameter portion, and the large diameter portion side is a vertically elongated circular hole in the mill set state. Arranged in a perfect circular hole shape as it goes to the mold and the smaller diameter side, set the side relief of the caliber to 0, and provide a fin-thickness gap between the caliber sides over the entire reduced-diameter part of the upper and lower roll dies. It is a roll die for a cold pilger mill for producing finned tubes.

[0007]

The outer fin fin tube of the present invention is manufactured by cold pilger rolling, and is therefore excellent in strength, toughness and hardness. In particular, those made of stainless steel are pipes with fins that have excellent corrosion resistance.

In the method for producing a pipe with fins on the outer surface by cold pilger rolling according to the present invention, the caliber shape of the upper and lower roll dies is made into a true circular hole type, and the large diameter portion side is changed into a vertical oval hole type in a mill set state. Arranged in a perfect circular hole shape as it goes to the smaller diameter side, providing a constant gap for the fin thickness between the shoulders of the upper and lower roll dies over the entire length of the reduced diameter part of the roll die, and from the caliber. Without adding side relief to prevent biting flaws, it is set to 0 and a fin-thickness gap is provided between the caliber sides over the reduced diameter area of the upper and lower roll dies. Roll Pilger.

Normally, in cold pilger rolling, the roll die 1 is reciprocated once to draw the raw material pipe 7, and then the raw material pipe 7 is rotated together with the mandrel 5 in the circumferential direction of the pipe by about 60 °, and at the same time, the raw material pipe 7 is rotated. Send the tube 7 a little and perform the next companding,
Repeat this.

However, in the method of the present invention, unlike this ordinary method, the roll die 1 is reciprocated once to make the material pipe 7
When the material is drawn, the material tube 7 is only fed without rotating in the circumferential direction, the next drawing is performed, and this is repeated. Then, as described above, the side relief of the caliber is set to 0, and the fin thickness gap 9 is provided on the shoulder portion of the roll die between the caliber sides over the entire reduced diameter portion 6 of the upper and lower roll dies, and the side relief is set to 0. Since a roll die is used, the raw material tube 7 is reduced in diameter and stretched by drawing and the raw material protrudes from the gap 9 at the shoulder portion of the roll die. However, the material tube 7 is not rotated but only fed to perform the next companding. Therefore, the material that has been further reduced in diameter and stretched and that has protruded from the gap 9 in the shoulder portion of the roll die earlier will further protrude without being crushed. Also,
Since the material is not rotated, it is pressed down onto the mandrel 5 by the upper and lower roll dies 1 and 1, so that the caliber 2
The diameter of the large-diameter part at the beginning of the diameter reduction is a perfect circular arc shape, but the hole shape is an up-and-down elliptical shape so that the fins of the material pipe 7 project and the inner surface of the finned pipe has a perfect circle shape. It is effective in becoming. That is, the inner surface is pulled when the fin comes out and the inner surface of the tube on the opposite side of the fin tends to be recessed in both fin sides.However, by making the oval shape as described above, The action of pushing inward occurs. However, since the hole-shaped shape becomes a perfect circle as it goes to the smaller diameter side, the product pipe 10 is manufactured as a perfect circular finned pipe.

[0011]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic explanatory view of cold pilger mill rolling. The cold pilger mill has a reduced-diameter portion 6 that has a semicircular cross section and that is continuously reduced, and a sizing portion 3 that is composed of a finished size caliber that is continuous with the reduced-diameter portion 6 and has a constant cross section. Connecting rod 1 that is attached to the roll stand 16 on the outer circumference
When the roll stand 16 is moved back and forth by 7, the pinion gear 13 attached to the roll die shaft 4 rolls on the fixed rack gear 12, and thereby, the two roll dies 1 that move up and down and roll forward and backward. With the mandrel 5 having a cross section that narrows toward the tip, the raw material tube 7 is cold drawn and passed through the diameter-reduced tube portion 8 to obtain the product tube 10. The sectional area of the product pipe 10 is about one-third and the length thereof is three times that of the material pipe 7.

In the companding, when the material tube 7 is companded by reciprocating the roll die 1 once, the material tube 7 is slightly fed and the next companding is carried out, and this is repeated.

FIG. 2 shows a caliber shape of the roll die 1 used for the Pilger rolling of the present invention, that is, a hole type which is a space between a millset upper and lower roll dies and a mandrel. 2 (a) shows that the rolling start end of the reduced diameter portion 6 having a large diameter is 1.0 sec.
1.0sec when the rolling end of small diameter is 0.0sec,
Caliber 2 of roll die 1 formed between upper and lower roll dies at 0.5 sec, 0.2 sec and 0.0 sec.
And the outline of the mandrel 5, and the gap 9 formed by the shoulders of the upper and lower roll dies on the caliber side is
This is a space where the material pipe protrudes during rolling and the fin 11 is formed. The size of the gap 9 extends over the entire area of the reduced diameter portion 6,
That is, it is the same in all sections, and this gap 9 is the thickness of the fin 11. FIG. 2 (b) shows the caliber 2 of the upper and lower roll dies in each section of the hole-shaped contour.
The hole type consists of a perfect circle in each section. As for the caliber side gap, only the gap 9 of 0.0 sec has the same size as that of all the shoulder gaps 9 in (a). The upper and lower arcs of the perfect circle of the caliber 2 shown in (b) are vertically separated from each other, and the upper and lower roll dies are mill-set so that the caliber side gaps are all the same gap 9 (a). Is. Therefore, in (a), the caliber shape of the upper and lower roll dies is a vertically elongated oval with a perfect circle extending vertically on the large diameter side of 1.0 sec.

When cold pilger rolling is performed using the roll die 1 described above, the material pipe 7 is drawn and thinned into the hole shape of each section shown in FIG. A part protrudes and forms a fin 11. The overhanging width of the fin 11 can be made constant by setting the material tube 7 having a specified size.

Since the metal pipe with fins on the outer surface of the obtained product pipe 10 made of stainless steel by cold pilger rolling has excellent dimensional accuracy, strength, corrosion resistance and hardness, the total length of the pipe is further increased. When the screw pipe is formed by twisting in the circumferential direction of the pipe, it can be used as a discharge pipe for perforation.

[0016]

[Example] Gap 9 on the caliber side of the upper and lower roll dies
Using the upper and lower roll dies 1, 1 having a diameter of 5 mm, the feed amount per rotation of the roll dies is 5 mm, and the material pipe 7
Rolling speed of the roll die is 50 without rotating
45m outer diameter made of SUS304 stainless steel as rpm
Cold pilger rolling of a material tube 7 having a thickness of 4.0 m, a thickness of 4.0 mm and a length of 4500 mm, an outer diameter of 25 mm ± 0.15 mm, and a wall thickness of 2.
A product pipe 10 of stainless steel having a fin of 5 mm ± 0.25 mm and a length of 15,000 mm and having an outer fin was obtained. The overhang length of the fin 11 was 4.0 mm ± 0.5 mm on one side, and the wall thickness of the fin 11 was 5.0 mm ± 0.15 mm.

[0017]

As described above, since the present invention is a metal tube with an external fin, which is formed by rolling with a cold pilger mill, an external fin tube made of stainless steel can be used. It is superior in dimensional accuracy to pipes, does not require a cold drawing process, and can be manufactured inexpensively and easily. Further, since it is an outer surface finned tube having high strength and excellent in corrosion resistance, the field of application of the finned tube can be expanded more than the field of application of the conventional finned tube by extrusion. Further, since the method of the present invention performs cold pilger rolling, the present invention has excellent effects such that a finned tube can be easily manufactured using stainless steel or the like as a raw material.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a cold pilger mill, (a)
Shows a mandrel shape and a drawn state of a metal tube in a partial cross section, and (b) is a plan view of a cold pilger mill.

FIG. 2 is a diagram showing a caliber shape in the reduced diameter portion of the upper and lower roll dies of a cold pilger mill and a gap between caliber sides at the shoulders of the upper and lower roll dies, where (a) is the upper and lower rolls in a mill set state. FIG. 3B is a diagram illustrating a hole type in each section of the dice and the mandrel at the reduced diameter portion, and FIG.

FIG. 3 is a perspective view of a partially shortened outer finned tube according to the present invention.

[Explanation of symbols]

 1 Roll Die 2 Caliber 3 Sizing Section 4 Roll Die Shaft 5 Mandrel 6 Reduced Diameter Section 7 Material Tube 8 Reduced Diameter Section 9 Roll Die Shoulder Gap 10 Product Tube 11 Fin Gear 12 Rack Gear 13 Pinion Gear 14 Reduced Diameter Final Point 15 Fin length 16 Roll stand 17 Connecting rod

Claims (3)

[Claims] 1. A pipe with fins on the outer surface, characterized in that, in cold pilger rolling, the material pipe is non-rotatably fed to form fins on both sides of the outer surface of the stretched pipe. 2. The caliber shape of the reduced diameter portion of the cold die of cold pilger rolling is formed into an arc shape of a perfect circle over the entire reduced diameter portion, and in the mill set state of the upper and lower roll dies, the caliber portion on the larger caliber diameter side is used. The depth from the mandrel axis is larger than the width, and the depth from the mandrel axis is smaller than the caliber width on the small caliber diameter side, and the caliber side between the upper and lower roll die shoulders is smaller. Roll dies are arranged so that the gap between them has a constant fin size and thickness in all areas of the reduced diameter portion, and the outer wall is characterized in that the material pipe is stretched and thinned by feeding only without rolling the material pipe. Pipe manufacturing method. 3. The caliber shape of the reduced diameter portion, which is a hole type of the upper and lower roll dies, is a circular arc shape of a perfect circle over the entire reduced diameter portion,
In the mill set state, the large diameter side is arranged in a vertically long circular hole type and as it becomes the small diameter side, it is arranged in a perfect circular hole type, eliminating the side relief of the caliber and reducing the diameter of the upper and lower roll dies. A roll die for cold pilger mills for producing finned pipes, characterized in that a fin thickness gap is provided between caliber sides over the entire area.