JPH0399708A - Method and device for manufacturing seamless steel pipe - Google Patents

Abstract

PURPOSE:To manufacture a high alloy steel seamless steel pipe of high quality by cooling the shell internal face by a cooling water during the piercing of a shell and controlling the temp. of the shell inner and outer faces at the temp. adaptive to working. CONSTITUTION:A seamless steel pipe is manufactured by a high alloy steel. In the process thereof, a shell 15 is pierced by advancing a mandrel bar 1. While under piercing the internal face of the shell 15 is cooled by injecting a cooling water to a piercing hole 16 from a nozzle port 13. The internal and external faces of the shell 15 are then controlled to the temp. adaptive for the work of the shell 15. A bottomed hole leading the coolant to the plug of a mandrel bar is provided. The shell can thus be maintained in an optimum temp. area.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a seamless steel pipe manufacturing method and apparatus,
More specifically, the present invention relates to a method and apparatus for manufacturing a seamless steel pipe using high-alloy steel, which prevents cracks from occurring by controlling the temperature of the inner and outer surfaces of the shell during drilling.

[Prior art] For example, when manufacturing a seamless steel pipe using a difficult-to-work material such as high alloy steel that is equivalent to or higher than 5USATO, Inco 800, etc., it is necessary to , and large cracks and other flaws occur on the inner surface.

Figure 8 is a diagram showing the temperature distribution in the wall thickness direction when drilling a hollow rolled pipe (hereinafter referred to as shell) made of high alloy steel. mm
The maximum temperature is reached at the position of the surface, and the temperature decreases toward the outer surface.

This phenomenon occurs when a material with high deformation resistance generates a large amount of heat during processing, resulting in high temperatures that may exceed the zero ductility temperature under certain conditions, causing large defects (a) such as cracks on the inner surface.

In order to suppress overheating, we changed the heating temperature depending on the material of the shell, made the shell hollow, etc. to reduce the degree of processing, and drilled holes, but if overheating cannot be suppressed even with these measures, The shell was stopped between the Piasa and the Elongator, and the temperature was lowered by cooling it from the outside or blowing air inside.

However, if this is done, the temperature of the outer surface will also drop, and if this becomes significant, the workability will be insufficient as shown by the solid line (■) in FIG. 7, and large defects (b) such as cracks will occur on the outer surface.

[Problem to be solved by the invention] As mentioned above, conventionally, the feeding of the shell between the pierce and the elongator is stopped to lower the temperature, so the rolling operation is interrupted during that time, resulting in time loss. This greatly hindered productivity improvement.

In addition, this often causes cracks and other flaws on the outer surface of the shell, resulting in various problems such as a decrease in yield.

The present invention has been made to solve the above-mentioned problems, and reduces loss time by cooling the inner surface of the shell during drilling with a piercer or elengater, controlling the temperature of the inner and outer surfaces, and reducing the temperature difference between the inner and outer surfaces. The object of the present invention is to provide a method and apparatus for manufacturing seamless steel pipes that are free from scratches and are free from the risk of producing flaws on the inner and outer surfaces.

[Means for Solving the Problems] The method for manufacturing a seamless steel pipe according to the present invention cools the inner surface of the shell with cooling water while drilling the shell, and controls the inner and outer surfaces of the shell to a temperature suitable for processing the shell. It was designed to do so.

In addition, in order to carry out the above manufacturing method, a hole with a bottom is provided in the plug of the mandrel bar for drilling to introduce cooling water for the mandrel bar, and a plurality of nozzle holes are provided that open from this hole with a bottom to the outer surface of the plug. It was established.

Furthermore, a through hole is provided in the center of the plug of the mandrel bar for drilling, and a member is provided for introducing cooling water for the mandrel bar into the through hole. It consists of connected cooling rods with nozzle holes that communicate with water channels.

[Function] When drilling a shell with a piercer and/or elongator, the cooling water of the mandrel bar is guided into the bottomed hole or cooling rod of the plug, and is jetted from the nozzle hole to cool the inner surface and reduce the temperature of the inner and outer surfaces of the shell. The temperature is controlled to match the material.

[Embodiment] FIG. 1 is a sectional view of an embodiment of a mandrel bar for a piercer used in the present invention. In the figure, 1 is a mandrel bar, which has a hollow structure for supplying cooling water.

Reference numeral 2 denotes a member (hereinafter referred to as a closing member) having a through hole in the center and closing the tip opening of the mandrel bar 1, and a guide having a plurality of balls 4 on the outer periphery and a through hole 5 in the center. A member 3 is integrally provided. Reference numeral 6 denotes a tip with a T-shaped cross section, a through hole 7 is provided in the center, the tip is inserted into the through hole of the closing part lug 2 via a spring 8, and the tip part is inserted into the through hole 5 of the guide part lug 3. Located within. Reference numeral 10 denotes a plug, which has a bottomed hole 11 with an inner diameter slightly larger than the outer diameter of the guide member 3 at its center, and four parts 12 formed on the inner wall at positions facing the ball 4. 13 is bottomed hole 1
A plurality of nozzle holes are slanted backward from 1 and are perforated radially to open to the outside. This plug 10 is formed by connecting the recess 12 and the ball 4 of the guide portion 3 to the mandrel bar.
1.

To make a hole in a shell using the mandrel bar 1 constructed as described above, as shown in FIG. 2, the shell 15 is loaded into the piercer and the mandrel bar 1 is advanced at the same time.

On the other hand, 20 kg/c of cooling water of 1.5 ρ/see, for example, is supplied from a cooling water source (not shown) to the hollow part of the mandrel bar 1.
Supply at ♂ pressure. As a result, the cooling water cools the mandrel bar 1 and is sent from the through hole 7 of the chip 6 to the bottomed hole 11 of the plaque 10 to cool the plug 11. This cooling water flows from the nozzle hole 13 to the perforation 1 of the shell 15.
6 and cools the inner surface to a temperature suitable for the material of the shell 15 (for example, 1000 to 1250°C).

The broken line ■ in FIG. 8 shows the temperature distribution in the thickness direction of the shell 15 rolled according to the present invention.According to the present invention, by efficiently cooling the inner surface of the shell 15, It is possible to reduce the temperature difference and control the temperature to a range that does not cause flaws.

In the above embodiment, a case where a solid shell 15 is rolled and perforated is shown, but the present invention can also be applied when rolling a shell (hollow shell) 17 that has been warped and made hollow, as shown in FIG. It can be implemented. In that case, a second bottomed hole Lla is provided from the bottomed hole 11 of the plug 10 toward the tip, and a plurality of nozzle holes L3a that are inclined forward from a are arranged radially. It is sufficient to set it in

With this configuration, cooling water is ejected from the nozzle hole 13a into the perforation 13a, thereby cooling the inner surface of the shell 17.

FIG. 4 is a sectional view of an embodiment of a mandrel bar for an elongator. In this embodiment, the bottomed hole of the plug 10 is extended to the tip and opened, and the opening is closed with a blind lid 20, and a plurality of nozzle holes 13b inclined forward are radially formed from the bottomed hole 111). It was established in

According to the plug 10 configured in this way, as shown in FIG.
The plug 10 is advanced while the inner surface is cooled by jetting cooling water, and the shell 21 is rolled to produce a steel pipe.

FIG. 6 is a sectional view showing still another embodiment of the present invention. In this embodiment, the tip of the hole provided in the plug 10 is opened to form a through hole IIc, and from the tip opening of this penetrator lie, a nozzle hole 13c having a water channel 23 in the center and provided at the tip A cooling rod 22 communicated with a water channel 23 is inserted, and its rear end is fixed to the guide member 3 with a screw or the like 24.

The function of the plug 10 constructed in this way is similar to that shown in FIGS. 3 and 5, but the nozzle hole 1.
Processing is easier compared to the case where 3a and 13b are provided,
Manufacturing costs can be reduced.

FIG. 7 is a diagram comparing the outer surface temperature of the shell in the rolling process (Piercer and Elongator) of a seamless steel pipe using Incoloy 825 between the conventional method (Figure a) and the present invention (Figure b). In the figure, P indicates Piasa, and E indicates Elongator. Note that the shell is shown as an example heated to 1150° C. in a heating furnace.

First, in the conventional method, as shown in Figure a, the temperature at the front end of the shell drops to about 980°C when it is loaded into the piercer, and the temperature at the rear end of the shell at the exit after being pierced by the piercer decreases to about 980°C. The temperature of is approximately 112
Heat to 5°C. Then, when the shell is charged into the elongator, the temperature at the front end of the shell decreases to about 1.00°C, but the temperature at the rear end at the exit increases to about 1170°C due to the perforation by the elongator, causing workability lame. . In addition, when the shell is left to cool between the Piasa and the Elongator, the outer surface temperature is approximately 1020° as shown by the broken line.
C (=1).For this reason, workability is insufficient and cracks may occur on the outer surface.

On the other hand, according to the present invention, by increasing the transport speed of the shell from the heating furnace to the piercer, as shown in FIG. By cooling the inner surface inside the shell, the rise in temperature due to the perforation of the shell upon exiting the piercer was also small, and the temperature at the rear end was able to be suppressed to approximately 1110°C. And the temperature when charging into Eronketa is about 1080℃.
℃, and since the inner surface was cooled according to the invention during drilling,
The surface temperature at the end of drilling remains at about 1140°C, and therefore no workability cracks or outer surface cracks occur.

In addition, when cooling the inner surface of the shell according to the present invention, the temperature can be adjusted by changing the size, number, angle, etc. of the nozzle holes provided in the plug, or by changing the amount of cooling water.

Although the embodiments of the present invention have been described in detail above, the structure of the mandrel bar plug according to the present invention is not limited to the structure of the embodiments, and can be modified as appropriate depending on the material, size, etc. of the shell.

[Effects of the Invention] As is clear from the above description, the present invention cools the inner surface by supplying cooling water while drilling the shell with a piercer and/or elongator, and adjusts the temperature of the inner and outer surfaces of the shell to the material. Since the temperature is controlled with high precision so that the temperature difference between the inner and outer surfaces is reduced, the shell can be maintained within an appropriate temperature range. Therefore, it is possible to manufacture a seamless steel pipe made of high-quality high-alloy steel without any flaws on the inner or outer surfaces.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view of an embodiment of the mandrel bar for piercing used in the present invention, Fig. 2 is an explanatory diagram of its operation, and Fig. 3 is an operation of another embodiment of the mandrel bar for piercer. 4 is a longitudinal sectional view of an embodiment of the mandrel bar for elongator, FIG. 5 is an explanatory diagram of its operation, FIG. 6 is a sectional view of another embodiment of the present invention, and FIG. 7 is a piercer and FIG. 3 is a diagram showing changes in surface temperature of the shell before and after perforation by an elongator, in which (a) shows the case according to the conventional method, and (b) shows the case according to the present invention. FIG. 8 is a diagram showing the state of temperature distribution in the thickness direction when drilling high alloy steel. 1: Mandrel bar, u, ub: bottomed hole, 11c: through hole, 13. L3a, 13b, 13c: Nozzle hole, 15.17, 21 Nigel, 1.6.1g, 19.
22: Perforation.

Claims (3)

[Claims] (1) In the process of manufacturing seamless steel pipes from high-alloy steel, the inner surface of the shell is cooled with cooling water while the shell is being drilled, and the temperature of the inner and outer surfaces of the shell is controlled to a temperature suitable for the processing of the shell. A method for manufacturing a seamless steel pipe characterized by: (2) In equipment for manufacturing seamless steel pipes using high-alloy steel, a hole with a bottom is provided in the plug of a mandrel bar for drilling to introduce cooling water for the mandrel bar, and a hole is provided on the outer surface of the plug from the hole with a bottom. A seamless steel pipe manufacturing device characterized by having a plurality of open nozzle holes. (3) In equipment for manufacturing seamless steel pipes from high alloy steel, a through hole is provided in the center of the plug of a mandrel bar for drilling, and a member is provided for introducing cooling water for the mandrel bar into the through hole, and 1. An apparatus for manufacturing a seamless steel pipe, characterized in that a cooling rod having a water channel in the center and a nozzle hole communicating with the water channel at the tip is connected to the member.