JPS6356292B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an induction heating device array that heat-treats a welded portion during the manufacture of electric resistance welded steel pipes.

[Background Art] In the production of ERW steel pipes, in order to improve the toughness of the welded part, (1) normalizing or annealing the welded part, or (2) normalizing or annealing the welded part and tempering after quenching. Processing may be performed. Here, it is a well-known fact that tempering treatment after quenching the weld zone is effective in improving toughness.

By the way, conventionally, as a welding part heating device for electric resistance welded steel pipes, there have been disclosed Utility Model Application No. 58-7860, Japanese Patent Publication No. 1983-61513,
Special Publication No. 56-52974 has been proposed. Since these conventionally proposed welding zone heating devices are intended for normalizing or annealing the weld zone, they must be spaced a certain distance from other welding zone heating devices adjacent to each other in the line direction. They are each fixedly arranged.

Therefore, conventionally, when performing tempering treatment after quenching of a welded part, normalization or annealing treatment and quenching treatment are performed online, and then tempering treatment is performed offline. Therefore, in this case, it is necessary to provide an off-line induction heating device exclusively for the tempering process, and a dedicated transport facility before and after the device is also required. In addition, when the tempering treatment is performed off-line as described above, the tube bends and re-straightening is required.

[Object of the invention] The present invention can be used not only for normalizing or annealing a welded part, but also for normalizing or annealing a welded part, and for tempering after quenching. It is an object of the present invention to provide an array of induction heating devices for welded parts of electric resistance welded steel pipes, which also makes it possible to perform tempering treatment on parts.

[Structure of the Invention] In order to achieve the above object, the present invention provides an induction heating device array for a welded section of an ERW steel pipe in which a plurality of induction heating devices are arranged, an upstream induction heating device and a downstream induction heating device. The heating devices are arranged so that they can approach and separate from each other, and the quenching device can be inserted between the induction heating device on the upstream side and the induction heating device on the downstream side, which are arranged apart from each other. .

[Specific Description of the Invention] Examples of the present invention will be described below with reference to the drawings.

FIGS. 1A and 1B are schematic diagrams showing one embodiment of the present invention. In this embodiment, the electric resistance welded steel pipe 1
On the conveyance line of 0, on the exit side of the welding machine (not shown),
A total of 8 induction heating devices 11 (11A, 11B, 1
1C, 11D, 11E, 11F, 11G, 11
H) are arranged consecutively. Here, the upstream induction heating devices 11A to 11D and the downstream induction heating devices 11E to 11H are arranged so as to be able to come into contact with and separate from each other,
Upstream induction heating devices 11A to 11D and downstream induction heating devices 11E to 11D are spaced apart from each other.
During 11H, a hardening device 12 as shown in FIG. 1B can be inserted.

The induction heating device 11 is constructed as shown in FIG. That is, a lower pedestal 15 is mounted on the upper part of the foundation 13 via rollers 14 for movement in the line direction. An upper pedestal 17 is mounted on the upper part of the lower pedestal 15 via rollers 16 for moving in the left-right direction. Further, the upper frame 17 is provided with an inverter 18 and an output transformer 19, and a linear inductor 20 is provided below the output transformer 19.
is provided. That is, when the electric resistance welded steel pipe 10 is heated by the induction heating device 11, in order to position the linear inductor 20 directly above the welded portion of the electric resistance welded steel pipe 10, the upper frame 17 is moved by the operation of the electric motor 21 for left and right movement. and further adjust and move the linear inductor 20 in the vertical direction using the hydraulic cylinder device 22 for vertical movement to maintain a constant distance between the outer surface of the welded part of the ERW steel pipe 10 and the lower surface of the linear inductor 20. shall be. The induction heating device 11 is moved in the line direction by moving the lower pedestal 15 in the line direction using an electric motor or the like, and at this time, the power cable can be supplied by the cable carrier 23.

As shown in FIG. 1B, the quenching device 12 consists of a forced water cooling pipe 24 and an on-off valve 25.

Next, a method of using the above-mentioned induction heating device array will be explained. First, for example, an extremely thick electric resistance welded steel pipe 10 having a plate thickness t of 19 mm or more is subjected to a normalizing or annealing process using six to eight induction heating devices 11 . Therefore, in this case, all the induction heating devices 11A to 11H are used in a continuous arrangement as shown in FIG. 1A.

On the other hand, for a medium-walled electric resistance welded steel pipe 10 with a plate thickness t of 12.7 mm or less, all induction heating devices 11A to 11 are used.
The downstream induction heating devices 11E to 11H of H are moved backward in the line direction, and the upstream induction heating devices 11A to 11D and the downstream induction heating devices 11E to 11H are moved backward in the line direction.
11H, the hardening device 12 is inserted, and the upstream induction heating devices 11A to 11D perform normalization or annealing treatment. After the hardening treatment is performed by the hardening device 12, the downstream side Induction heating device 1
Tempering treatment is performed according to steps 1E to 11H. In addition,
After quenching the above welded part, the plate thickness t of the tempered material is
The reason for specifying it to be 12.7 mm or less is that if the plate thickness t exceeds 12.7 mm, the specified cooling rate cannot be achieved in the vicinity of the inner surface of the tube by quenching using unidirectional forced water cooling from the outer surface of the tube. This is because it cannot be done.

In addition, in the induction heating device row, the inductor frequencies of the downstream induction heating devices 11E to 11H are as follows:
Since it is also used for tempering processing, it is necessary to set it lower than the inductor frequency of the upstream induction heating devices 11A to 11D. That is, when the frequency of the induction heating devices 11E to 11H on the downstream side is high, the direct heating depth is shallow and the heat uniformity is poor.Therefore, in order to improve the heat uniformity, it is necessary to set the frequency low. . Specifically, the inductor frequency of the upstream induction heating devices 11A to 11D is set to 500Hz, and the inductor frequency of the downstream induction heating devices 11E to 11D is set to 500Hz.
The inductor frequency of 11H is 300Hz.

Further, the heating coil widths of the downstream induction heating devices 11E to 11H are the same as those of the upstream induction heating devices 11A to 11H.
It needs to be lower than the heating coil width of 11D.
This is because the width of the heating coil needs to be set wider in order to reliably temper the heating zone performed on the upstream side during the tempering process on the downstream side.

In addition, in the induction heating device 11, it is important to make the inductor 20 follow the welded part in order to perform a satisfactory heat treatment. Move at a constant gap along the surface. That is, each unit is individually provided with a seam detector and a gap sensor, and the obtained signals are processed by a control computer to perform feedback control. Regarding temperature control, a known thermometer is used to measure the temperature at the center of the heating section, and a temperature control computer performs feedback control.

Figure 3 shows the plate thickness t of 19 mm using 8 induction heating devices.
This is a temperature rise curve for the inner and outer surfaces of an ERW steel pipe that is normalized or annealed.

Figure 4 shows that an ERW steel pipe with a plate thickness t of 12.7 mm is normalized or annealed by four induction heating devices located on the upstream side, and then heated to four induction heating devices located on the downstream side. This is a temperature rise curve for the inner and outer surfaces of the tube when tempering is performed.

Figure 5 shows the shear py results when the welded part of an ERW steel pipe made of steel type A with an outer diameter of 508 mm and a plate thickness of 12.7 mm is quenched and then tempered as shown in Figure 4 above. FIG. According to this Figure 5, the transition temperature vTrs shows a value equivalent to that of the base material, and the absorbed energy vE _-46 at the test temperature of -46°C is
It is recognized that the value is higher than that of the base metal. Note that this Charpy test used a test material with a cross section of 10 mm x 10 mm and a V-notch depth of 2 mm.

[Effects of the Invention] As described above, the present invention provides an arrangement in which an upstream induction heating device and a downstream induction heating device are mutually connected in a row of induction heating devices for a welded portion of an ERW steel pipe in which a plurality of induction heating devices are arranged. The quenching device can be inserted between the upstream induction heating device and the downstream induction heating device, which are arranged so as to be able to approach and separate from each other. Therefore, the induction heating device array according to the present invention cannot be used for normalizing or annealing a welded part, nor can it be used for normalizing or annealing a welded part, or for tempering after quenching.

[Brief explanation of the drawing]

FIG. 1A is a schematic diagram showing a usage state of an induction heating device row according to an embodiment of the present invention, FIG. 1B is a schematic diagram showing another usage state of the same induction heating device row, and FIG.
The figure is a front view showing an induction heating device according to an embodiment of the present invention, FIG. 3 is a diagram showing a heating pattern for normalizing or annealing treatment by the induction heating device array according to the present invention, and FIG. 4 is a diagram showing the heating pattern of the induction heating device according to the present invention. FIG. 5 is a diagram showing the heating pattern of the post-quenching and tempering process using the induction heating device array according to the present invention, and FIG. 5 is a diagram showing the sharpie results when the induction heating device array according to the present invention is used. 10
...Electrical welded steel pipe, 11...Induction heating device, 11A-11
D... Upstream induction heating device, 11E to 11H... Downstream induction heating device, 12... Quenching device.

Claims (1)

[Claims] 1. In an induction heating device row for a welded part of an electric resistance welded steel pipe in which a plurality of induction heating devices are arranged, the upstream induction heating device and the downstream induction heating device are arranged so as to be able to approach and separate from each other, and are arranged so as to be separated from each other. A row of induction heating devices for welded parts of electric resistance welded steel pipes, characterized in that a hardening device can be inserted between an upstream induction heating device and a downstream induction heating device.