JPS63215309A - Manufacturing equipment for seamless steel pipe - Google Patents

Abstract

PURPOSE:To inexpensively obtain a seamless steel pipe having high-strength and high-toughness by cooling the blank pipe by a cooling facility before inserting into a reheating furnace, after rolling through a mandrel mill. CONSTITUTION:The cooling equipment 60 to perform the cooling of the blank pipe is provided between the mandrel 30 and reheating furnace 40. A billet 70 being a material is bored by a Mannesmann piercing mill 20 after heating in a heating furnace 10, the blank pipe 70a rolled through the mandrel mill 30 is cooled below the Ar1 transformation temperature by the cooling equipment 60. Further, reheated by the reheating furnace 40, then the final rolling is performed by a stretch reducer 50 to finish. By this method, transport working and a heat treating furnace necessary for the heat treating are eliminated and improvement of the product efficiency and reduction of the manufacturing cost are accomplished.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to manufacturing equipment for manufacturing seamless steel pipes with excellent strength and toughness. [Prior Art] A method for manufacturing seamless steel pipes includes After perforating the billet heated to ~1250°C with a piercer, a plug mill,
A manufacturing method that involves various processes such as a reeler (polishing machine), a sipe (or stretch reducer), and a mandrel mill after perforation.

There is a method of manufacturing through a reheating furnace and a stretch reducer.

[Problem that the invention seeks to solve]

However, both methods had the disadvantage that the temperature during billet heating was too high, resulting in coarse grains and poor toughness. Therefore, steel pipes that require high toughness have conventionally been subjected to heat treatment such as normalization, which has caused new problems such as increased manufacturing man-hours, multiple process operations, and increased costs.

On the other hand, in the manufacturing technology for thick plates such as raw plates for line pipes for cold regions that require strength and toughness, the rolling temperature is controlled to a low temperature (e.g. below the Arl transformation point) in order to obtain strength and toughness, and the austenite grains are A method of finely recrystallizing the ferrite structure to make the transformed ferrite structure fine, and a method of reheating and rolling at a temperature below the Arl transformation point are known. JP-A-50-1955 and Utility Model Publication No. 61-1922 applied this thick plate manufacturing technology to a method for manufacturing seamless steel pipes using a plug mill, reeler, and sipe 1.
Similar temperature control is aimed at improving the strength and toughness of seamless steel pipes.

That is, JP-A No. 50-1955 discloses a method in which only the outer periphery of a raw pipe of H diameter is cooled with a water injection nozzle during transportation, and finish rolling is performed after rapid cooling to just below the Arl transformation point. No. 1922 is a method in which a cooling bed serving as a bypass is provided between the polished tube equipment and the reheating furnace, and the raw tube is cooled (mainly air-cooled) to below the Arl transformation point.

However, in the former method, the temperature of the raw tube immediately after the reeler is 90
Due to the high temperature of 0 to 950℃, the raw tube is placed in Ar1 during the transportation time.
It is difficult to lower the temperature below the transformation point, and this method does not necessarily cool the tube uniformly in the longitudinal and circumferential directions, there is a risk of bending, and there is a large temperature difference between the inner and outer surfaces of the tube. However, the latter method requires a separate cooling bed, which increases equipment costs and requires a large amount of space. Q: There are problems. The present invention has the above-mentioned problems.

Apart from the above two techniques for manufacturing seamless steel pipes using plug mills, reelers, sipes, etc., this method involves drilling a billet and then using a mandrel mill.

The aim is to improve manufacturing equipment for manufacturing seamless steel pipes through a reheating furnace and a stretch reducer so that seamless steel pipes with high strength and high toughness can be obtained at low cost.

[Means for solving problems]

Therefore, 1 the present invention, as shown in FIG.
, Piasa (2), Mandrel Mill (38 Reheat Furnace (4),
In the seamless steel pipe manufacturing equipment installed in the stretch reducer (5) (or sipe) section, cooling equipment (6) for cooling the raw pipe is provided between the mandrel mill (3) and the reheating furnace (4). ) is the basic feature.

[For production]

The temperature of the raw pipe immediately after the reeler in the continuous seamless steel pipe manufacturing equipment line, which includes a heating furnace, a piercer, a plug mill, a reeler, and a sipe, is as high as about 900 to 950°C. In Utility Model Publication No. 61-1922, it is not easy to cool the raw tube below the Arl transformation point. On the other hand, heating furnace (1), Piasa f2), 7
In the continuous line of seamless steel pipe manufacturing equipment, there is a 7-drel mill (3), a reheat furnace (4), and a stretch reducer (5).

Mandrel mill (3) After rolling, from the raw tube to the mandrel bar
When it is pulled out, it is already at about SOO°C, so as in the present invention, after rolling in the mandrel mill (3), the raw tube is cooled in the cooling equipment (6) before being charged into the reheating furnace (4). In this case, it can be easily cooled to below the Arl transformation point (approximately 600° C.). Therefore, by quickly cooling the pipe to below the Arl transformation point using the cooling equipment (6), reheating it in the reheating furnace (4), and finishing it with the stretch reducer (5), a seamless steel pipe with high strength and high toughness can be produced. Obtainable.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 2 shows seamless steel pipe manufacturing equipment according to an embodiment of the present invention, which includes a heating furnace a1, a Mannesmann Piaser kiln, a mandrel mill (1), a cooling equipment (60), and a reheating furnace (40).
) and a stretch reducer (50). Then, the billet (70) serving as the material is heated in a heating furnace α
[After being heated to about 1200° C., the raw pipe (70a) that has been perforated with a Mannesmann piercer and rolled with a mandrel mill is cooled to below the Arl transformation point in a cooling facility (60). Furthermore, it is reheated in a reheating furnace (40) and final rolled in a stretch reducer (50) for finishing.

Here, the cooling equipment (60) has an equipment configuration and equipment as shown in FIG. An apparatus configuration as shown in FIG. 4 was used in this example.

The cooling equipment (60a) shown in FIG.
) (61b) and the turning roller (6ta) (ax
b) A cooling fan (62) that air-cools the outer periphery of the raw tube (70a) when it is rotating on the turning roller (sxa) (6xb), and when the raw tube (70a) is placed on the turning roller (sxa) (6xb). It consists of an air blow nozzle (63) that blows cooling air onto the inner surface of the raw pipe (7 oa) from the ffi section side.

In the cooling equipment (60a), two raw pipes (70
In order to cool the inner and outer surfaces of a), three sets of turning rollers (aia In order to cool the inner and outer surfaces at the same time, a total of six sets are installed.By rotating each base pipe (70a) in the circumferential direction, the cooling fan (62) can uniformly spread the outer circumference in the circumferential direction. Three cooling fans (62) are provided in the axial direction of the two blank tubes (70a) arranged in parallel above the two blank tubes (70a). ) can be cooled uniformly in the length direction.Furthermore, the air blow nozzle (63) is installed on the end side of the two blank tubes (7oa) in order to cool the inner surfaces of the two blank tubes (7oa). There are two in total, one each,
The raw pipe (70a) is a turning roller (sla) (6ib
) is installed so that it rises when placed on top of the base tube (7Qa) and blows out cooling air onto the inner surface of each base tube (7Qa).

In addition, three rollers (64) provided in parallel with the turning roller (ala>(axb) group) are connected to the cooling bag [1 (60
The raw tube (70a) cooled in step a) is transferred to the next reheating furnace (40).
This is a conveyor roller for conveying to. Furthermore, when the raw tube (70a) is transferred from the turning rollers (61a) (61b) to these conveyor rollers (64), it is configured to move laterally appropriately using a walking beam or the like.

In the cooling equipment (60a) having the above device configuration, the raw tubes (7 oa) rolled by the mandrel mill (to) are placed one by one in parallel on the turning rollers (61a) and (61b) by the conveying device. The turning roller (s1aX
6th) rotates in the circumferential direction thereof. At this time, three cooling fans (62) are rotating above the two blank tubes (7oa), uniformly cooling the outer peripheral surface of the blank tube (70a) in its circumferential direction and length direction. On the other hand, air blow nozzles (63) are raised at the ends of each of the blank tubes (70a), and blow cooling air onto the inner surfaces of these blank tubes (70a) to cool the inner surfaces at the same time.

In this way, since the two raw tubes (70a) are simultaneously cooled from their inner and outer surfaces, the cycle time is not reduced (,8
It can be rapidly cooled from a temperature of about 00° C. to a temperature below the Ar transformation point. and the conveyor roller (
64) and is transported to the next reheating furnace (40).

The cooling equipment (6ob) shown in FIG.
) (61b) and the turning roller (siaX6t
b) A cooling fan (62) that air-cools the outer periphery of the raw tube (70a) when it is rotating on the top, and a cooling fan (62) that air-cools the outer periphery of the raw tube (70a) when the raw tube (70a) is placed on (61a) (61b). , has a cooling bar (65a) that moves inside the base pipe (7oa) in its longitudinal direction, and the cooling bar (65a)
) and an internal forced cooling device (65) that cools the inner surface of the raw pipe (7oa) while spouting high-pressure water from the wood pipe (70a). It consists of an external forced cooling device (66) that is installed around the outer circumference of the tube and jets high-pressure water around the entire circumference to cool the outer circumference of the base pipe (7 oa).

In this cooling equipment, turning rollers (61a) (61b
) and the cooling fan (62) are almost the same as the equipment array described above, only that they are configured to cool the raw pipes (7 oa) one by one. On the other hand, in this cooling equipment, a forced cooling device (65 x 66) for internal and external surfaces is newly installed to jet high-pressure water onto the internal and external surfaces of the base tube (70a) to further improve cooling efficiency.

Among them, the internal forced cooling device (65) supports the end of the cooling bar (65a) with a support stand (ssb).

A transport conveyor (6
The transport conveyor (65c) is fixed to the belt surface of 5e).
By driving the cooling bar (65a)'i:
The blank pipe (70a) is configured to be movable in the inner longitudinal direction. A flexible hose (65d) is attached to the end of the cooling bar (65a) in the support base (6sb), and high pressure water is supplied from a boost pump (not shown) to the cooling bar (65a).
5a) moves inside the raw tube (70a), high pressure water is spouted from the tip of the cooling bar (SSa) and
a) Enables forced cooling of the entire inner surface.

The outer surface forced cooling device (66) is composed of a link-shaped outer surface disscaler through which the raw tube (70a) can be inserted through its center. ) to the next reheating furnace (40), the conveyor roller (64
) is installed in the direction in which the wood pipe (701L) is being transported, and high-pressure water supplied by a booster pump (not shown) or the like is sprayed onto the outer circumferential surface of the wood pipe (701L) while the wood pipe (701L) is being transported.

In the cooling equipment (6ob) consisting of the above device configuration.

Turning rollers (6xa) (6th) and cooling fan (62) uniformly cool the outer circumferential surface of the raw pipe (70a) in the circumferential direction and length direction, and the raw pipe (70 m)
Cooling nozzle of internal forced cooling device (65) from pipe joint side
65a) and move it inside, and forcefully cool the inner surface of the raw pipe (70 m) by jetting high-pressure water from its tip.

Thereafter, the cooling bar (65a) is extracted from the inside of the raw pipe (70a), and the raw pipe (70a) is moved to the conveyor roller (64).
) and transferred toward the reheating furnace (40). At this time, the outer surface forced cooling device (66) sprays high-pressure water onto the outer circumferential surface of the raw pipe (7 oa) being transferred to forcibly cool the outer circumferential surface.

In this way, in addition to air cooling the outer circumferential surface of element Ii# (70a), its inner and outer surfaces are cooled with an inner and outer forced cooling device (65
), cooling to a temperature below the Arl transformation point is performed more quickly than with the cooling equipment (aQa).

Next, the AFJA and others installed conventional seamless steel pipe manufacturing equipment that was installed in the order of heating furnace, piercer, mandrel mill, reheating furnace, and stretch reducer, as well as the mandrel mill (end) and reheating furnace (40). Cooling equipment (60a) shown in Figure 3 between
Using the seamless steel pipe manufacturing equipment of this example equipped with
The mechanical properties of these pipes were investigated, and the results shown in the table below were obtained.

As is clear from the above table, the oil country tubular goods rolled by the equipment of this example have higher absorbed energy and better mechanical properties than those manufactured by the conventional equipment. Therefore, heat treatment such as normalization is not required,
Transportation costs and heat treatment furnace fuel costs were reduced, and a significant reduction in manufacturing costs was achieved.

〔Effect of the invention〕

According to the seamless steel pipe manufacturing equipment of the present invention described in detail above, it is possible to obtain steel pipes that are free from bending, have stable quality, and have mechanical properties equivalent to conventional products that have been subjected to heat treatment such as normalization. This eliminates the need for transportation work and heat treatment furnaces required for these heat treatments, resulting in improved production efficiency and a significant reduction in manufacturing costs. Further, in the present invention, the cooling equipment does not require a large space and can be installed at low cost, so it can be easily installed in a conventional mill line.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the equipment configuration of the present invention, Fig. 2 is an explanatory diagram showing the equipment configuration according to an embodiment of the invention, and Fig. 3 is a perspective view showing an example of the cooling equipment in this embodiment. , FIG. 4 is a perspective view showing another example of the cooling equipment. In the figure, (1) αQ is the heating furnace, (2) ■ is Piazza, (3)
M is mandrel mill% (4X40) is reheating furnace, (5
X50) is stretch reducer% (6) (60) (6
0a) (60b) is cooling equipment, (61a) (61b)
is a turning roller, (62) is a cooling fan, (63
) indicates an air blow nozzle, (65) indicates an internal forced cooling device, and (66) indicates an external forced cooling device. Patent applicant: Nippon Kokan Co., Ltd. Inventor: Yamazaki-Otoko Fuyuhiko Kajiyama Representative Patent attorney: Sho Yoshihara Sando
Masatoshi Tomabechi

Claims (1)

[Claims] 1. Heating furnace, Piasa, mandrel mill, reheating Heat furnace, stretch reducer or sizer Seamless steel pipe manufacturing equipment installed in the following order: between the mandrel mill and the reheat furnace. Cooling equipment was installed to cool the raw pipes. Seamless steel pipe manufacturing equipment characterized by: 2. In the seamless steel pipe manufacturing equipment mentioned above, Turning that rotates the pipe in its circumferential direction The growler and the raw pipe rotate on the roller. A cooling fan that air-cools the outer periphery of the Then, the raw pipe is placed on the turning roller. When placed, the inner part of the raw pipe is removed from the end side. Air blower that blows cooling air onto the surface Configuring the cooling equipment from Zuru Claim 1, which is characterized by: seamless steel pipe manufacturing equipment. 3. Seamless steel according to claim 1 In pipe manufacturing equipment, the raw pipe is a turning roller that rotates the When the raw pipe is rotating on the rollers, A cooling fan that cools the outer periphery and the When the raw pipe is placed on the coating roller, Cooling that moves inside the tube in its longitudinal direction The cooling bar has a high pressure Cools the inner surface of the tube while jetting water Internal forced cooling device and raw tube are the next reheating furnace A ring is placed around the outer periphery of the raw pipe when it is transferred to Then high pressure water is ejected all around it. An external forced cooling device that cools the outer circumference of the pipe. It is characterized by configuring its cooling equipment. Seamless as described in claim 1 Steel pipe manufacturing equipment.