JP3073680B2 - Tube with outer fins, method for producing the same, and roll die used for the method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal finned tube, and more particularly to a long finned tube 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 a finned tube is generally an aluminum alloy that can be easily extruded, and the finned tube made of the aluminum alloy produced by such extrusion is used for applications such as a heat exchanger. However, aluminum alloy materials are sometimes unsatisfactory for members requiring high strength, and finned tubes made of high-strength materials such as steel are required. There is a need for stainless steel seamless steel finned tubes for use under a variety of harsh conditions. However, it is not easy to manufacture a finned tube made of steel or the like by extrusion. That is, there is a problem in dimensional accuracy due to hot extrusion, and furthermore, cold drawing is required. by the way,
Seamless stainless steel tubing is manufactured by cold pilger rolling. However, there has been no finned tube of a seamless stainless steel tube manufactured by cold pilger rolling.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a seamless stainless steel pipe finned tube by cold pilger rolling, which cannot be manufactured conventionally, and to provide a method of manufacturing the same. And to provide a roll die for use in the manufacturing method.

[0004]

The present invention for solving the above problems SUMMARY OF THE INVENTION The outer surface fins, characterized in that it has Tatsushide fins to extension tube outer surface on both sides by feeding the non-rotating element tube in co Rudopiruga rolling It relates to the attached pipe .

According to the first aspect of the present invention, the caliper shape of the reduced diameter portion of the cold pillger rolling roll die is a perfect circular arc over the entire area of the reduced diameter portion, and when the upper and lower roll dies are mill set, the caliber diameter is reduced. Assuming that most of the rolling start is 1.0 section (hereinafter referred to as “sec”) and the rolling end on the smaller diameter side is 0.0 sec, the rolling start is 1.0 sec.
The caliber depth from the mandrel axis relative to the caliber width side large west, potash from the mandrel axis relative to the caliber width taken to proceed from the caliber diameter portion to the caliber small-diameter portion
Reduce the bar depth gradually, and between the upper and lower roll dies
Roll dies are arranged so that the gap between them becomes a fixed fin thickness in all areas of the reduced diameter part, that is, the diameter of the caliber
The large part is in the shape of an oblong hole and the small diameter part of the caliber
It is arranged in the shape of a perfect circle as it becomes
Fillet between shoulders of upper and lower roll dies over the entire length of the reduced diameter part
A method of manufacturing a tube with an external fin, characterized in that a constant gap corresponding to the thickness is provided, and the raw material tube is elongated and thinned and rolled only by feeding without rotating.

According to the second aspect of the present invention, the caliber shape of the diameter-reduced portion, which is the hole shape of the upper and lower roll dies, is made to be a perfect circular arc over the entire diameter-reduced portion, and in the mill set state, the large-diameter portion has an oblong hole. It is arranged on the mold and in the shape of a perfect circle as it goes to the small diameter side, the side relief of the caliber is set to 0, and a gap of the fin thickness is provided between the caliber sides over the entire reduced diameter part of the upper and lower roll dies. A roll die for a cold pilger mill for producing finned tubes.

[0007]

The outer finned tube of the present invention is manufactured by cold pilger rolling, and therefore has excellent strength, toughness and hardness. In particular, a tube made of stainless steel is a tube with an external fin having excellent corrosion resistance.

According to the method for producing a tube with an outer fin by cold pilger rolling of the present invention, the caliber shape of the upper and lower roll dies is made into a perfect circular hole, and the large-diameter portion is formed into an elongated circular hole in a mill set state. It is arranged in the shape of a perfect circle as it gets closer to the small diameter side, and a constant gap of the fin thickness is provided 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 using side relief to prevent biting flaws, it was set to 0 to provide a gap of fin thickness between the caliber sides throughout the reduced diameter part of the upper and lower roll dies, and the upper and lower roll dies were used to cool the material pipe. Pilger rolling.

Normally, in cold pilger rolling, the material tube 7 is drawn by reciprocating the roll die 1 once, and then the material tube 7 is rotated together with the mandrel 5 by about 60 ° in the circumferential direction of the tube. Send a little pipe 7 and do the next drawing,
Repeat this.

However, in the method of the present invention, unlike the ordinary method, the roll die 1 is reciprocated once and the material pipe 7 is moved.
When the material is drawn, only the feed is performed without rotating the material pipe 7 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, a gap 9 having a fin thickness is provided at the roll die shoulder between the caliber sides across the entire diameter reduced portion 6 of the upper and lower roll dies, and the side relief is set to 0. Since a roll die is used, the material pipe 7 is reduced in diameter and stretched by drawing and the material protrudes from the gap 9 at the roll die shoulder. However, the next companding is performed only by feeding without rotating the material pipe 7. Therefore, the material which has been further reduced in diameter and stretched and which has previously protruded from the gap 9 of the roll die shoulder portion protrudes further without being crushed. Also,
Since the material is not rotated, it is pressed down on the mandrel 5 from above and below by the upper and lower roll dies 1 and 1, so that the caliber 2
The shape of the large diameter portion at the beginning of the diameter reduction is a perfect circular arc shape, but as a hole shape, it is made into an oblong shape up and down, so that the protruding fin portion of the material tube 7 and the inner surface shape of the finned tube are rounded It is effective in becoming. That is, when the fins come out, the inner surface is pulled and the inner surface of the tube on the opposite side of the fins tries to dent into both fins. The effect of pushing inward occurs. However, since the shape of the hole becomes a perfect circle toward the small diameter side, the product tube 10 is manufactured as a perfect circular finned tube.

[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 formed of a reduced diameter caliber that has a semicircular cross-section and is continuously reduced, and a sizing portion 3 formed of a finished dimension caliber that is continuous with the reduced diameter portion 6 and has a constant cross section. Connecting rod 1 that is provided on the outer periphery and attached to roll stand 16
The pinion gear 13 attached to the roll die shaft 4 rolls on the fixed rack gear 12 by being moved back and forth by the roll stand 16 by the upper and lower roll dies 16, whereby the upper and lower two roll dies 1 perform forward and backward rolling. The raw material tube 7 is cold drawn by the mandrel 5 having a cross section that becomes thinner toward the tip, and the product tube 10 is obtained through the reduced diameter tube portion 8. The cross-sectional area of the product tube 10 is about one third and the length is three times as large as the material tube 7.

In the drawing, when the material tube 7 is drawn by reciprocating the roll die 1 once, the material tube 7 is fed a little, the next drawing is performed, 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 shape which is a space between the mill-set upper and lower roll dies and the mandrel. FIG. 2A shows the start of the large diameter rolling of the reduced diameter portion 6 for 1.0 sec.
1.0 sec when the rolling end of the small diameter is 0.0 sec,
Caliber 2 of roll dice 1 formed between upper and lower roll dice 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 in which the material tube protrudes during rolling and a 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 the gap 9 is the thickness of the fin 11. FIG. 2B shows the outline of the hole shape in each section with the caliber 2 of the upper and lower roll dies.
The hole shape is a perfect circle for each section. Only the gap 9 of 0.0 sec is the same size as the gap 9 of all the shoulders in FIG. The upper and lower roll dies are mill set so that the upper and lower arcs of the true circle of the caliber 2 shown in (b) are vertically separated from each other, and the gaps on the caliber side are all the same gap 9 (a). It is. Therefore, in (a), the caliber shape of the upper and lower roll dies is a vertically long ellipse with a true circle extending up and down on the large diameter side of 1.0 sec.

When cold pilger rolling is performed using the above-mentioned roll die 1, the raw material tube 7 is drawn and thinned into a hole shape of each section shown in FIG. Part of the protrusion protrudes to form fins 11. The overhang width of the fin 11 is always constant by setting the material pipe 7 having a specified size.

The metal tube with fins on the outer surface of the obtained product tube 10 made of stainless steel by cold pilger rolling is excellent in dimensional accuracy, strength, corrosion resistance, and hardness. When formed into a screw tube by twisting in the circumferential direction of the tube, it can be used as a discharge tube for drilling.

[0016]

EXAMPLE A gap 9 on the caliber side of the upper and lower roll dies
Using the upper and lower roll dies 1 and 1 having a length of 5 mm, the feed amount per rotation of the roll dies is set to 5 mm and the material pipe 7
The rolling speed of the roll dies is reduced to 50 without rotating
SUS304 stainless steel outer diameter 45m as rpm
Material pipe 7 having a thickness of 4.0 mm and a length of 4500 mm is subjected to cold pilger rolling to have an outer diameter of 25 mm ± 0.15 mm and a thickness of 2.
A stainless steel tube 10 having an outer fin having a length of 5 mm ± 0.25 mm and a length of 15000 mm was obtained. The overhang length of the fin 11 was 4.0 mm ± 0.5 mm on one side, and the 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 external fins formed by rolling with a cold pilger mill, it is possible to obtain a tube with external fins made of stainless steel, It has excellent dimensional accuracy compared to tubes, does not require a cold drawing step, and can be manufactured at low cost and easily. Further, since the outer finned tube has high strength and excellent 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 an excellent effect such that a finned tube can be easily manufactured using stainless steel or the like as a material.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a gap between a caliber shape of a caliper shape of a reduced diameter portion of an upper and lower roll die of a cold pilger mill and a caliber side at a shoulder portion of the upper and lower roll dies. FIG. 4B is a diagram illustrating a hole shape in each section of a reduced diameter portion of a die and a mandrel, and FIG.

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

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 roll die 2 caliber 3 sizing part 4 roll die shaft 5 mandrel 6 reduced diameter part 7 material pipe 8 reduced diameter pipe part 9 gap of roll die shoulder part 10 product pipe 11 fin 12 rack gear 13 pinion gear 14 reduced diameter part final point 15 Fin length 16 Roll stand 17 Connecting rod

Claims (2)

(57) [Claims] 1. A a caliber shape of the reduced diameter portion of the cold pilger rolling roll-dies is arcuate grooved circularity over the entire area of the reduced diameter portion, the mill set state of the upper and lower roll-dies, large diameter of the caliber Part side into an oblong hole shape, and
And arranged in the shape of a perfect circle as it approaches the small diameter side of the caliber.
Up and down over the entire length of the reduced diameter part of the upper and lower roll dies.
Provide a fixed gap between the shoulders of the roll dies for the thickness of the fins,
A method for producing a tube with external fins, characterized in that a raw material tube is elongated and thinned and rolled only by feeding without rotating. 2. A caliber shape of a diameter-reduced portion, which is a hole type of an upper and lower roll die, is a perfect circular arc shape over the entire diameter-reduced portion,
In the mill set state, the large diameter part is arranged in a vertically long circular hole and the smaller diameter part is arranged in a perfect circular hole, eliminating the side relief of the caliber and reducing the diameter of the upper and lower roll dies. A roll die for a cold pilger mill for producing finned tubes, wherein a gap of fin thickness is provided between caliber sides throughout the entire area.