JPS5855216B2 - Post annealing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a boss annealing device installed in an electric resistance welded tube manufacturing line.

ERW steel pipes are made by continuously feeding copper strips, bending them so that the edges on both sides butt against each other, and forming a tube.The ends that are butted are heated with high frequency and lateral pressure is applied to weld them together. Manufactured.

After cutting the inner and outer bead excess of the welded part of this ERW steel pipe, it is sent to the boss annealing device, where it is heated at a frequency of 1 to 10 KHz.
Electromagnetic induction heating is performed using high frequency waves to perform annealing or normalization, thereby removing residual stress and improving the structure.

Figure 4 shows an electromagnetic inductor 10, which is the main part of the Bost annealing equipment.
It shows.

This electromagnetic inductor 10 consists of a rectangular parallelepiped iron core 11 and a conductive part 12 arranged around its outer periphery.

The iron core 11 has its longitudinal direction aligned with the steel pipe transport direction, and is made by laminating a large number of silicon steel plates in that direction.

Each steel plate has an inverted U-shape, and a groove is formed on the lower surface of the iron core 11.

The conductive part 12 is a central conductor 12 fitted into this groove.
a, and an outer conductor 12b that has a U-shape in plan view and is arranged so as to hold each of the upstream and downstream halves of the iron core 11.
, 12c and an outer conductor 12b.

A terminal portion 12d is connected to the terminals on both sides of each of the terminal portions 12c and is disposed so as to straddle the iron core 11.

12e, and the outer conductors 12b and 12c are connected to each terminal of the central conductor 12a at the lower part of the inner inner surface of the husband.

A high frequency power source using a high frequency generator or a SIRISK is connected to the terminal sections 12d and 12e via an output transformer (none of which is shown), and high frequency power is applied to the conductive section 12.

The arrow in the conductive portion 12 indicates the direction of current in a certain cycle.

The center conductor 12a has an outer conductor 12b. Since the current flows in the direction opposite to that shown in 12c, this central conductor 12
At this time, the magnetic flux caused by the current a interlinks with the steel pipe SP as shown by the dashed line in the figure.

Eddy currents due to this interlinkage magnetic flux flow through the steel pipe, and the welded portion WS is heated by the Joule heat, achieving the intended purpose.

However, in recent years, the quality required for ERW steel pipes has become higher quality, and the demand for thick-walled pipes has also increased. The trend is to install two or three electromagnetic inductors in tandem.

Looking at the functions of each inductor in a Bost annealing system equipped with multiple electromagnetic inductors, the inductor in the final stage plays a major role in determining the quality of the welded part, but the inductor in the previous stage has a preheating function. It's just a matter of fulfilling your purpose.

This is believed to be because the final stage inductor substantially determines the maximum heating temperature, which has a great effect on annealing and normalizing.

Based on the above-mentioned considerations, the present invention has a structure in which the welded part of the ERW pipe is preheated by resistance heating, and then electromagnetic induction heating is performed by an electromagnetic inductor, without using an expensive inductor. It can cope with higher quality pipes, thicker walls, and faster manufacturing speeds. Furthermore, by devising the electrode arrangement of the preheating means, efficient resistance heating can be performed, and the entire device can be made smaller and cheaper. The purpose is to provide a boss annealing device that can be realized.

The present invention will be described in detail below based on drawings showing embodiments thereof.

The device of the present invention uses one electromagnetic inductor similar to the conventional one (in some cases, multiple inductors may be arranged in tandem), and directly energizes the welded part of the ERW pipe on the upstream side in the direction of ERW pipe transfer. This is provided with preheating means for resistance heating.

FIG. 1 shows the main parts of the boss annealing apparatus according to the present invention together with the electric resistance welded steel pipe SP.

In the device of the present invention, an electrode block 20 constituting a preheating means is installed downstream of an external speed cutting device (none of which is shown) disposed downstream of the squeeze roll, and further downstream of the electrode block 20, as in the conventional case. An electromagnetic inductor 10 is provided.

As described above, the electromagnetic inductor 10 has a rectangular parallelepiped shape with a groove extending in the longitudinal direction formed on the lower surface, and a laminated core 11 whose longitudinal direction coincides with the direction of transport of the steel pipe SP, and which is fitted into the groove. The arranged central conductor 12a, this central conductor 12
Outer conductors 12b are connected to both ends of a, have a U-shape in plan view, and are arranged so as to hold about half of the upstream and downstream ends of the iron core 11.

12c and a conductive portion 12 consisting of terminal portions 12d and 12e connected to terminals on both sides of the outer conductor 12 b t 12 c and disposed so as to straddle the iron core 11. The terminal portions 12d and 12e are not shown in the figure. It is exactly the same as the conventional structure that the welded portion WS of the steel pipe SP is heated by energizing the conductive portion 12 with high frequency power through a high frequency power source via a non-conductive output transformer.

Next, the electrode block 20 of the preheating means will be explained.

This electrode block 20 is located above the center of the steel pipe SP transfer area.
That is, a large number of electrodes 22 are mounted and supported on a mounting frame 21 extending in the direction of the steel pipe transport force above the passage area of the welded portion WS and arranged in the direction in which the mounting frame 21 extends.

FIG. 2 is an enlarged perspective view of a part of the electrode block, in which the mounting frame 21, which is suspended so that it can be raised and lowered using an air cylinder or the like as a required support member, is attached to two side plates made of insulating material. 21a.

21a are opposed to each other and connected at key points to form a framework that is elongated in the steel pipe transfer direction as a whole, and the side plates 21a
, 21a are connected between the beams 21b and 2Ib, two electrodes 22 are arranged as a set in the steel pipe transport direction, and a guide groove 21c is formed on the opposite side surface, that is, the inner surface, of the side plates 21a, 21a. , 21c.

The electrode 22 is made of prepared alloy, and has a rectangular parallelepiped-shaped support part 22a at the upper part, and a small plate-shaped slider 22b whose lower end part is rounded and tapers in one direction. Both of them are removable so that they can be replaced when the slider 22b becomes worn.

The two electrodes 22.22 are connected to respective sliders 22b, 22b.
The tapered surfaces of the two electrodes face each other, a V-shaped gap is formed between them, and an insulating plate 22c such as a glass base material laminate is interposed between both electrodes to insulate them. and two sliders 22b.

22b is used as a slider assembly.

Both cisternae movers 22b and 22b are connected to the respective support portions 22a.
, 22a are slidably fitted into the guide grooves 21c, 21c.

Disposed below and parallel to the mounting frame 21 is a slider guide 23 made of an insulating material, which is capable of sliding the sliders 22b, 22b of the combined electrodes 22.22. Guide frame portions 23a closely surrounding each other and adjacent guide frames 23
a, a connecting rod 23b connecting between 23a, and connecting rod 2
3b is a screw pestle 2 which is suspended and fixed to the beam 21b of the mounting frame 21.
The slider guide 23 can be moved up and down depending on the position of the nut screwed into the screw 24.

An arc-shaped leaf spring 25 is provided between the beam 21b and the upper surface of the support portion 22a of each electrode 22, and biases the electrode 22 downward.

With this configuration, when the mounting frame 21 is lowered to an appropriate height, the slider 22b of each electrode 22 comes into sliding contact with the welded part WS located at the top of the steel pipe SP with an appropriate pressure.

As will be described later, each electrode 22 is connected to a predetermined terminal on the secondary side of a transformer 30 provided for resistance heating via a flexible lead wire 22d.

Although not particularly shown, the side plates 21a, 21 of the mounting frame 21
The size of the electrode block 20 may be reduced by passing cooling water through the support portion 22a of the electrode 22, or by passing cooling oil through the support portion 22a of the electrode 22.

Next, the slider 22b will be explained.

This slider 22b contacts the steel pipe SP and energizes it,
Joule heat is generated due to the resistance of the steel pipe SP and the welded part W
Used to preheat S.

Therefore, it is desirable that the contact with the steel pipe SP be made stably and with low contact resistance.

Since the welding part WS has a smooth surface by cutting off the excess from '' by an external bead cutting device, the above-mentioned requirements can be satisfied by making the width of the slider 22b a little narrower than the welding part dimension. .

However, because the surrounding atmosphere is poor, the cutting surface is contaminated with oil and dust between the bead cutting device and the electrode block 20, which causes poor contact and arcs, resulting in a decrease in the quality of the steel pipe and damage to the slider. There is a possibility that this will lead to wear and tear.

In order to reliably avoid this, at a position close to the upstream side of the electrode block 20, polish an area approximately twice the width of the electrode block 20, including the welded part, with a wire brush or grinder, and then use a dust collector to remove the polished layer. The contact between the slider and the steel pipe can be made more reliable by this method.

In addition, if this preheating method is used, the welding area will be at most 300mm.
Since the temperature rises only to about ℃, there is no risk of scale forming on the surface and getting caught up in the slider on the downstream side.

Next, the manner of connection between the transformer 30 of the preheating means of the apparatus of the present invention and each electrode 22 will be explained.

FIG. 3 is a wiring diagram schematically showing this aspect, in which the primary winding 31 to be connected to the preheating high-frequency power source 40 is one winding, whereas the secondary winding 32 has many windings. Each secondary winding 32 has a potential of the same polarity applied to the two electrodes 22, 22 that are tied together to form a set, and each secondary winding 32 has a potential of the same polarity applied to the two electrodes 22, 22 of the adjacent set facing each other. The opposing electrodes are connected to each other so that potentials of different polarities are applied to the opposing electrodes.

In other words, potentials of different polarities are applied to opposing sliders of adjacent slider sets, thereby energizing the sliders.

Then, at a certain point, each electrode will take the +- polarity as shown in Figure 3, and the current will flow between the opposing electrodes of adjacent pairs, and no other current will flow into it. The heating of unnecessary parts due to the dispersed flow of current is avoided, and selective heating of the welded part can be performed effectively.

Furthermore, by making the connections as described above, the inductance of the steel pipe is reduced, making it easier for current to flow.

As mentioned above, in order to reduce unnecessary power consumption due to current dispersion, it is desirable to make the distance between the sliders that should be energized as equal as possible, and also to shorten the distance to some extent. is effective, for example, reducing the number of sliders to 1m.
Preferably, the number of sliders is 10 per slider (slider spacing is approximately 20 cyrr).

The secondary winding of the transformer 30 does not need to be a large number of independent windings, but may be a single winding with a large number of taps from which an equal voltage can be drawn.

Regardless of the configuration of the transformer, the voltage between the secondary terminals, the impedance between the primary and secondary windings, and other transformer specifications must be determined by heating the welded part WS to approximately 300°C. It is determined so that the maximum possible load current can be obtained.

The power source for the preheating means as described above is not limited to a high frequency power source, but may be a commercial frequency power source.

When using a high frequency power source, current dispersion is less likely to occur and power usage efficiency is high.

Furthermore, although the surface current tends to increase due to the skin effect, there is no problem in preheating since internal heating due to heat conduction can be expected.

External impeders, which are sometimes installed in welding equipment in an electric resistance welded steel pipe production line, may be provided on both sides of the electrode block 20 to more effectively distribute the current in the pipe circumferential direction.

On the other hand, when a commercial frequency power source is used, the current penetrates deep enough without the influence of the skin effect, and a uniform preheating effect can be obtained in the depth direction.

However, since the current is more easily dispersed than when using a high frequency power source, it is necessary to increase the arrangement density of the sliders.

Therefore, it can be said that it is economical to rely on a high-frequency power source if an existing high-frequency power source is available, and to rely on a commercial frequency power source if it is not available.

When installing other car invention devices, please use the electrode block 20.
Consideration should be taken to suppress ground leakage current, such as using rubber rolls as rolls for transferring steel pipes directly under the ground.

The apparatus of the present invention configured as described above moves the electrode block 20 and the electromagnetic inductor 10 up and down according to the outer diameter of the steel pipe to be manufactured, and the former is slid by the air cylinder supporting the mounting frame 21 and the leaf spring 25. The positions of the movers 22b are determined so that they are in contact with the steel pipe under appropriate pressure, and the latter is secured with an appropriate distance (lift-off amount) from the steel pipe, and energization is started at the same time as production begins. do.

Then, the steel pipe welded part WS is preheated to about 300°C by resistance heating by electricity passing through the electrode 20, and then when it reaches the area where the electromagnetic inductor 10 is installed, it reaches the temperature required for annealing or normalizing. The intended purpose of Bost annealing can be distantly related.

The preheating means consisting of the electrode 22 and others has the function of replacing the previous electromagnetic inductor in a conventional boss annealing device equipped with a plurality of electromagnetic inductors. Alternatively, it is possible to increase the manufacturing speed.

A plurality of slider assemblies of the device of the present invention are arranged in parallel at appropriate lengths in the direction of passage through the welded portion, each consisting of two sliders arranged close to each other and insulated from each other. Electrical potentials of different polarities are applied to the opposing sliding elements, and electricity is passed between the opposing sliding elements to heat them, so that the current is applied to areas other than the welded area, that is, areas that do not require heating. Efficient heating can be performed without dispersion.

Further, the preheating means of the present invention can be constructed in a smaller size and at a lower cost than an electromagnetic inductor, and the electrothermal conversion efficiency is much higher, so that power consumption can be significantly reduced, and the present invention has excellent effects.

[Brief explanation of drawings]

Fig. 1 is a perspective view of the main parts of the device of the present invention, Fig. 2 is a perspective view of the electrode block, Fig. 3 is a schematic diagram showing the connection between the preheating transformer and the electrodes, and Fig. 4 is a perspective view of the electromagnetic inductor. It is a diagram. 10... Electromagnetic inductor, 20... Electrode block, 21... Mounting frame, 22... Electrode, 22b... Slider , 30...Transformer.

Claims (1)

[Claims] 1. An electromagnetic inductor arranged along the welded part passage area of an electric resistance welded pipe manufactured by bending a continuously fed metal strip into a cylindrical shape and welding opposing edges, and the electromagnetic induction A plurality of slider assemblies, each consisting of two sliders in contact with the electric resistance welded pipe placed close to each other and insulated from each other on the upstream side of the child, are arranged in parallel at appropriate lengths apart in the welding passage direction. It is connected to a power source in order to apply potentials of different polarities to opposing sliding pieces of adjacent slider sets, and the welded portion of the ERW pipe is A boss annealing device characterized by comprising a preheating means for resistance heating.