JPS62118973A - Adhesion preventing method for cut spatter to inner peripheral face of steel pipe - Google Patents

Abstract

PURPOSE:To effectively prevent the adhesion of the cut spatter to the inner peripheral face of a steel pipe by inserting into the steel pipe the cylindrical shielding body made of steel plate having smaller outer diameter than the inner diameter of the steel pipe in the length within the necessary range before and behind the cutting position in cutting the steel pipe in the necessary length. CONSTITUTION:A steel pipe P is cut in the necessary length by the cutting device 1 by a gas, plasma, etc. which is located at the oblique upper part of the turning steel pipe P. In this case, the cylindrical shielding body 2 made of steel plate having about 50mm smaller outer diameter than the inner diameter of the steel pipe P as well as having the length in the necessary range before and behind the cutting position is inserted into the steel pipe P. The spatter which disperses while under welding of the steel pipe P is not adhered on the inner wall face of the steel pipe P but adhered on the outer peripheral face of the cylindrical shielding body 2 made of steel plate which is inserted into the steel pipe P.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method for preventing adhesion of melt spatter to the inner circumferential surface of a steel pipe.

``Prior art'' For example, on a line that manufactures large-diameter spiral steel pipes by forming steel strips into a spiral shape and welding the joints, the spiral steel pipes are cut into required lengths using, for example, gas or plasma. There is a process to do this.

When a spiral steel pipe is cut by gas or plasma, spatter is scattered during the cutting process and adheres to the inner circumferential surface of the pipe at the cut part.

Spatter adhering to the inner circumferential surface of the pipe not only reduces product quality but also causes flaws during processing in subsequent processes. Splash on the inner circumferential surface of the pipe within the required length range.
An anti-adhesion agent was applied (see Japanese Patent Application Laid-open No. 53400948).

``Problems to be Solved by the Invention'' By the way, in order to apply a spatter adhesion prevention agent to the inner circumferential surface of a spiral steel pipe, as disclosed in Japanese Patent Application Laid-open No. 53-100948, A pipe start end detection device is provided after the pipe cutting position of a pipe cutting device along the progress line of the steel pipe, and a pipe start end detection device is supported approximately at the center of the steel pipe in front of the cutting start position of the cutting device, and a spunter adhesion prevention agent is applied in the radial direction. A solenoid-operated injector equipped with an injecting tip, and a control current sent to the solenoid of the injector in response to a detection signal from the pipe start end detection device, so that the required length range before and after the planned cutting line of the steel pipe is This requires equipment that includes a control device with a timer that sprays the spatter adhesion prevention agent onto the inner circumferential surface of the pipe, and this equipment requires a large amount of investment, which poses a problem in its implementation.

"Means for Solving the Problem" The present invention prevents adhesion of spatter from melting spatter to the inner circumferential surface of the steel pipe by an extremely simple means without requiring special equipment that requires a large capital investment. It has been made possible.

That is, as shown in FIG. 1, the present invention uses a gas or plasma fusing device 1 located obliquely above the rotating steel pipe P to melt and cut the steel pipe P to a required length. A steel plate cylindrical shield 2 having a length in the required range before and after the position and an outer diameter approximately 500 smaller than the inner diameter of the steel pipe P is expanded into the steel pipe P, and the steel pipe P is cut to the required length by the fusing device 1. It melts right away.

``Effect'' As shown in Fig. 1, the spatter scattered during the melting of the steel pipe P does not adhere to the inner circumferential surface of the steel pipe P.
It adheres to the outer peripheral surface of the steel plate cylindrical shield 2 inserted therein.

``Example'' Figure 2 shows the method of the present invention being applied to a line in which a large diameter spiral steel pipe P is manufactured by forming a steel strip S into a spiral shape and making the joint contact f6. At each time, when fusing is performed by the /8@device 1 on the trolley 3, a cylindrical shielding body 2 made of H4 plate having the required length before and after the fusing position is inserted into the spiral steel tP, and the spiral This is an embodiment in which a steel pipe P is cut into required lengths by a fusing device l.

In this case, a support plate 2a is provided at the rear end of the steel plate cylindrical shield 2 so that the steel plate cylindrical shield 2 does not advance together with the spiral steel pipe P, and a hook 2b is rotatably attached to this support plate 2a. Attach the spiral steel pipe P to this hook 2b.
A wire 4 fixed to, for example, a forming roll frame (not shown) on the upstream side of the roller is connected.

Further, a flaw prevention ring 2c is attached to the outer periphery of the front and rear ends of the steel plate cylindrical shielding body 2 to prevent scratches from forming on the inner circumferential surface of the spiral steel pipe P.

Furthermore, if the steel plate cylindrical shielding body 2 is made of a WtsIil plate, the temperature will rise faster due to residual heat during fusing, and fusing spatter can be deposited with high efficiency.

However, if the cylindrical shielding body 2 is made of steel plate, a hole will be easily formed in the cylindrical shielding body 2 by the fusing sputter, so as shown in Fig. It is better to insert the interior cylindrical body 5 into the cylindrical shielding body 2.

Furthermore, as shown in FIG. 1, the flow of spatter scattered when cutting the rotating steel pipe P has three dimensions in the t=i direction of the drag line. The outer diameter of the shaped shield 2 is determined by the three dimensions mentioned above.

According to the inventor's experiments, it was found that the relationship between the sputter flow and the three dimensions differs depending on the wall thickness of the steel pipe P and the conveyance speed of the steel pipe P.

For example, in Figure 4 (A), the wall thickness is 6.0 mm and the conveyance speed is 2.3 mm.
Fig. 4 (B) shows the flow of spatter when steel pipe P is cut at a rate of 12.0 m/min.
1), conveyance speed 1.78++ 7 minutes (2.0m 7 minutes)
shows the flow of spatter when each steel pipe P is fused,
Figure 4 (C) shows meat W, 9.0-thick, conveyance speed 2.4 m.
This figure shows the flow of the spangoo when the steel pipe P is fused at a speed of 70 mm, and the three dimensions under the conditions shown in FIG.

Therefore, in order to satisfy a<53mm, the steel plate cylindrical shield 2
For example, in the case of a steel pipe P with an inner diameter of 600 fl, a steel plate cylindrical shield 2 with an outer diameter of 550 am may be used.

``Effects of the Invention'' As described above, the present invention provides a method for cutting a steel pipe to a required length by cutting the steel pipe to a required length by cutting the steel pipe to a required length. Since the steel plate cylindrical shield having an outer diameter is inserted into the steel pipe, the spatter scattered during the melting of the steel pipe is removed from the outer peripheral surface of the steel plate cylindrical shield inserted into the steel pipe. Therefore, no spunter was attached to the inner peripheral surface of the steel pipe.

In addition, the adhesion of spatter to the inner circumferential surface of the steel pipe can be extremely effectively prevented by the extremely simple method of sweeping a cylindrical shield made of steel plate into the steel pipe to be melted. It is economical and can be easily applied to existing steel pipe fusing equipment without any additional work.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the principle of the method of the present invention, FIG. 2 is an explanatory diagram showing an embodiment of the method of the present invention, FIG. 3 is a perspective view of an embodiment of a cylindrical shield made of steel plate, and ), (B), (C)
2A and 2B are explanatory diagrams showing that the state of sputter flow during steel pipe melting differs depending on the wall thickness of the steel pipe and the conveyance speed of the steel pipe. P... Steel pipe, ■... Fusing device, 2... Steel plate cylindrical shield, 5... Interior cylindrical body Fig. 1 Fig. 2

Claims (1)

[Claims] When cutting the steel pipe to the required length, the length must be within the required range before and after the cutting position, and the length should be 50 m longer than the inner diameter of the steel pipe.
A method for preventing adhesion of weld spatter to the inner circumferential surface of a steel pipe, the method comprising inserting a cylindrical shield made of steel plate having an outer diameter as small as 0.0 m into the steel pipe.