JPH0334430B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an energization method and device in an electric resistance welded steel pipe manufacturing line.

[Prior Art] In an ERW steel pipe manufacturing line, a pair of electrodes ( (contact tip) in a pressed state, welding current is applied to the welding point in the V-shape area and both edges of the raw tube, and both edges of the raw tube are heated to the temperature required for welding, and then squeeze rolls are used to It is possible to obtain an electric resistance welded steel pipe by pressing both edges of the raw pipe.

[Problems to be Solved by the Invention] However, as shown in FIG. 4, when microscopically observing the current-carrying region where the outer surface 1 of the tube edge portion and the electrode 2 are in contact with each other, it is found that Contact part 3
and a non-contact part 4. Therefore, in the conventional energization method, since the electrical contact point between the outer surface 1 of the tube edge and the electrode 2 moves, a spark phenomenon (local arc discharge) occurs and spark defects are transferred to the tube surface. becomes.

In addition, in the conventional energization method described above, in order to reduce the contact resistance between the outer surface 1 of the edge part of the raw pipe and the electrode 2 and improve the energization state, the electrode 2 is pressed against the outer surface 1 of the edge part of the raw pipe with strong pressure. As a result, the electrode 2 scrapes away the scale (black scale) that has formed on the outer surface 1 of the edge portion of the raw pipe. This scraped scale jumps into the V-shape region of the raw pipe, causing spot defects and impairing the quality of the weld. Moreover, under the action of the strong pressing force, the electrode 2
life expectancy decreases.

The present invention aims to improve welding quality and extend the life of electrodes.

[Means for Solving the Problems] The present invention as set forth in claim 1 provides an electric resistance welded steel pipe manufacturing method in which electrodes are brought into contact with the outer surfaces of both edge portions of the raw tube in a pressed state, and welding current is applied to both edge portions of the raw tube. In this method of supplying electricity in a line, electricity is supplied while filling a conductive material in the electrically conductive areas where the outer surfaces of the electrode and the edge portions of the tube are in contact with each other.

The present invention as set forth in claim 2 provides an electric resistance welded steel pipe manufactured by having electrodes that can be brought into contact with the outer surfaces of both edge portions of the raw tube in a pressed state and that enable welding current to be applied to both edge portions of the raw tube. In the energizing device in the line,
The electrode is formed so that the pump that pumps the good conductive material in the good conductive material storage part is connected to the pressure feeding piping connected to the pump, and the good conductive material that the pump pumps is connected to the edge of both the electrode and the raw pipe. and a pressure-feeding passage that allows the current to flow out to the energized areas that contact each other on the outer surfaces of the two.

[Function] According to the present invention as described in claims 1 and 2, the following effects are achieved.

Electricity is supplied while filling a well-conducting material between the outer surfaces of both edge portions of the tube and the electrodes, and a state of complete electrical contact can be formed between the outer surfaces of both edge portions of the tube and the electrodes. Therefore, it is possible to suppress the occurrence of spark phenomena and to suppress the occurrence of spark defects.

The conductive material filled between the outer surface of both edges of the raw pipe and the electrode functions as a lubricant between the two, thereby reducing the amount of scale removed by the electrodes and suppressing the occurrence of spot defects. , it is also possible to extend the life of the electrode.

[Example] Fig. 1 is a schematic diagram showing the main parts of an embodiment of the present invention, Fig. 2 is a side view showing the whole of the same embodiment, and Fig. 3 is a welding state of a general electric resistance welded steel pipe manufacturing line. FIG.

In the electric resistance welded steel pipe manufacturing line, as shown in FIG. , a pair of electrodes 14
are brought into contact with each other in a pressed state, and a welding current is applied to the welding point 15 of the V-shape region 12 and both edges of the raw pipe,
Both edge portions of the raw tube are heated to a temperature necessary for welding, and then both edge portions of the raw tube are pressed together by the squeeze roll 16, thereby making it possible to obtain the electric resistance welded steel pipe 17. In Figure 3, 18
is the outer bead. Also, in Figure 2, 1
9 is a contact shoe, 20 is a flexible adapter, and 21 is an electrode pressure adjustment section.

In this embodiment, a tank 23 serving as a storage section for a highly conductive material such as graphite paste, and a pump 24 for pumping the conductive material in the tank 23 are mounted on a support base 22 made of an electrically insulating material. We are prepared. On the other hand, inside the electrode 14 there is a pressure feeding passage 2.
A pressure feeding pipe 27 made of an electrically insulating material and connected to the pump 24 is connected to an inlet 26 of the pressure feeding passage 25. Pumping passage 25 for electrode 14
is opened in a current-carrying region where the outer surface 13 of both edge portions of the raw pipe and the electrode 14 are in contact with each other, making it possible to continuously fill the non-contact portions 28 of the two with a highly conductive material. 29 is the outer surface 13 of both edge parts of the raw pipe and the electrode 1
This is the contact part with 4.

According to the above embodiment, the outer surface 1 of both edge portions of the raw pipe
A state of complete electrical contact is formed between the electrode 14 and the electric resistance welded steel pipe 17, suppressing the occurrence of a spark phenomenon.
It becomes possible to suppress the occurrence of spark defects on the surface of the steel. In addition, the outer surface 13 of both edge parts of the raw pipe
A highly conductive material filled between the electrode 14 and the electrode 14 functions as a lubricant between the two, and as a result,
The amount of scale removed by the electrode 14 is reduced, thereby suppressing the occurrence of spot defects and also making it possible to extend the life of the electrode 14.

Figures 5 and 6 show graphite as a good conductive material.
FIG. 3 is a diagram showing a specific implementation result of the present invention using a 60% graphite-based paste.

Figure 5 shows the case where the high current density (line speed) is 50 m/min under the electrode pressure of 30 kg, and the broken line shows the case where the low current density is 30 m/min. The case is shown by a dashed line. According to FIG. 5, it is recognized that the higher the current density and the higher the pipe forming speed, the more likely spark defects will occur.

In FIG. 6, the case where the electrode pressure is 50 Kg is shown by a broken line, and the case where the electrode pressure is 30 Kg is shown by a dashed line under conditions where the pipe forming speed is 50 m/min.
According to FIG. 6, it is recognized that when the electrode pressure is in the range of 30 to 50 kg, the highly conductive material acts effectively and does not make a large difference in the occurrence of spark defects. From the above, in order to prevent the occurrence of spark defects, it is necessary to increase the pump pressure for pumping the conductive material to 8.
It is recognized that the electrode pressure should be at least Kg/cm ² and 30Kg.

FIG. 7 is a front view showing the surface condition of an electric resistance welded steel pipe (outer diameter 10 inches, wall thickness 10 mm) manufactured by a conventional method. Spark defects with a depth of 0.05 to 0.08 mm and a length of 10 to 15 mm were observed over the entire surface length of this ERW steel pipe.

On the other hand, FIG. 8 is a front view showing the surface condition of an electric resistance welded steel pipe (outer diameter 10 inches, wall thickness 10 mm) manufactured by the method of the present invention. In this electric resistance welded steel pipe, only one spark flaw is observed per 1 m of surface length, and the spark flaw has a depth of 0.01 mm and a length of 5 to 10 mm. That is, according to the present invention, it is possible to improve the surface quality of the electric resistance welded steel pipe.

[Effects of the Invention] As described above, the present invention according to claim 1 has the following advantages:
In an energization method in an ERW steel pipe manufacturing line in which welding current is applied to both edges of the raw pipe, the current is applied while filling the current-carrying area where the electrode and the outer surface of the raw pipe are in contact with each other with a material with good electrical conductivity. This is what I did.

Further, the present invention as set forth in claim 2 provides an electric welding welding machine having electrodes that can be brought into contact with the outer surfaces of both edge portions of the raw tube in a pressed state and that can supply a welding current to both edge portions of the raw tube. In an energizing device in a steel pipe manufacturing line, an electrode is formed so that a pump that pumps a good conductive material in a good conductive material storage section is connected to a pressure feeding piping connected to the pump, and the electrode is connected to a pump that pumps a good conductive material in a good conductive material storage section. , it has a pressure-feeding passage that allows the current to flow to the current-carrying area where the electrode and the outer surfaces of both the edge portions of the blank tube contact each other.

Therefore, according to the present invention, it is possible to improve welding quality and extend the life of the electrode.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the main parts of an embodiment of the present invention, Fig. 2 is a side view showing the whole of the same embodiment, and Fig. 3 is a perspective view showing the welding state of a general electric resistance welded steel pipe production line. , Fig. 4 is a schematic diagram showing the main parts of the conventional energization method, Fig. 5 is a diagram showing the relationship between pump pressure, pipe forming speed, and spark flaw occurrence state, Fig. 6
The figure is a diagram showing the relationship between pump pressure and electrode pressure and the state of spark flaw occurrence, Figure 7 is a front view showing the surface texture of an ERW steel pipe produced by the conventional method, and Figure 8 is a diagram showing the surface texture of an ERW steel pipe produced by the method of the present invention. FIG. 3 is a front view showing surface properties. 11...Made tube, 13...Outer surface, 14...Electrode,
17... ERW steel pipe, 23... Tank (good conductive material storage section), 24... Pump, 25... Pressure feeding passage,
27...Pressure piping, 28...Non-contact part, 29...
contact part.

Claims (1)

[Scope of Claims] 1. In an energization method in an ERW steel pipe manufacturing line, in which an electrode is brought into contact with the outer surface of both edge portions of the raw tube in a pressed state and a welding current is applied to both edge portions of the raw tube, the electrode and both edges of the raw tube are A method for energizing an electric resistance welded steel pipe production line, characterized by energizing while filling a conductive material in the energizing regions that contact each other on the outer surfaces of the sections. 2. In an energizing device for an ERW steel pipe manufacturing line, which has electrodes that can be brought into contact with the outer surfaces of both edge portions of the raw tube in a pressed state and that enable welding current to be applied to both edge portions of the raw tube, good electrical conductivity is required. The electrode is formed so that the pump that pumps the conductive material in the material storage part and the pressure-feeding piping connected to the pump are connected, and the well-conducting material that the pump pumps is connected to the outer surface of both the electrode and the edge of the raw pipe. 1. An energization device for an electric resistance welded steel pipe manufacturing line, characterized in that it has a pressure-feeding passageway that allows energization to flow into energized regions that abut each other.