JPH0533287B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to heat treatment equipment for subjecting large diameter steel pipes to various heat treatments in a production line for large diameter steel pipes such as UOE steel pipes.

In general, on steel pipe production lines, various heat treatments such as quenching, tempering, and normalizing are often performed on steel pipes after pipe production. Usually, the patterns (heat patterns) are different.
That is, the heating rate (temperature increase rate) and cooling rate differ depending on the purpose of heat treatment, the steel type, etc., and there are also differences in whether or not the maximum heating temperature is maintained.

If we classify the heat treatment in the conventional conventional steel pipe manufacturing process, it can be classified as monotonous heating and cooling, or heating → holding →
Cooling was broadly divided into two types, and heat treatment equipment such as batch furnaces and induction heating equipment was installed separately depending on each steel pipe production line.

By the way, recently, 3.5%Ni steel or 9%Ni steel
When welding UOE steel pipes made of Ni-containing low-temperature steel, known as Ni steel, etc., by submerged arc welding, welding material (wire) is
A method has been developed that uses a so-called co-metal welding material with a composition close to that of Ni steel.
In this case, in order to improve the low-temperature toughness of the co-metal weld, as a heat treatment after welding, it is held for a short time in a specific temperature range during the heating process before quenching, and then the temperature is raised to the quenching temperature and quenched. A tempering method was then developed and patented in a separate application. According to this heat treatment method, it is possible to significantly improve the low-temperature toughness of the co-metallic weld, which was considered the biggest problem in submerged arc welding of Ni-containing low-temperature steel pipes using a cometal-based welding consumable. It is possible to improve low-temperature toughness through short-time heat treatment without unnecessarily long heat treatment, so there is no need to reduce the speed of the pipe-making line. is expected to be applied.

However, as mentioned above, heat treatment in a pattern that temporarily holds heat during the temperature raising process before quenching is not performed on conventional steel pipe production lines, and therefore the above heat treatment is performed using heat treatment equipment in conventional steel pipe production lines. If we try to do this, various problems will arise. For example, if the process is carried out in a batch type furnace, it is difficult to carry out continuous treatment while transporting the steel pipes, and the heating rate is also slow, making each treatment time long and inefficient. There is a problem that the original purpose of improving toughness is lost, and the scale of the equipment needs to cover the entire length of the pipe. Huge equipment will be required. Furthermore, even if an attempt is made to perform the above-mentioned heat treatment using a heat treatment equipment that uses an induction heating device, the conventional equipment does not particularly consider maintenance during the temperature raising process. It was difficult to carry out heat treatment.

On the other hand, the above heat treatment pattern is applied to the manufacture of special steel pipes called Ni-containing low-temperature steel pipes using alloy welding materials by submerged arc welding, and will vary depending on the applied steel type. Since there is a high possibility that a specific heat treatment pattern will be required, installing specialized heat treatment equipment that is compatible with the above heat treatment pattern on the pipe making line will eliminate the flexibility of the line and make it difficult to use when making pipes of other steel types. A new problem arises in that the steel pipe cannot be subjected to appropriate heat treatment.

By the way, as a heating device for induction heating treatment of metal materials such as pipe materials, JP-A-52-122207 discloses a heating device in which a plurality of heating coil units for induction heating through pipe materials etc. are arranged in series. A device has been proposed that facilitates the replacement work when replacing heating coil units and the level adjustment of each heating coil unit in accordance with the heating temperature and heating time required for the tube material.

The heating device disclosed in JP-A No. 52-122207 is designed with only the heating of the material in mind, and does not take into account holding or cooling at the heating temperature. The heat treatment pattern cannot be adapted to any arbitrary heat treatment pattern. However, since each heating coil unit is said to be easy to replace, if the heat retention device (heat retention unit) and cooling device (cooling unit) are provided so that they can be replaced in accordance with the heating coil unit, each of these devices can be easily replaced. It is believed that by changing the arrangement of the elements, it becomes possible to match the desired heat treatment pattern.

However, the heating device of the above-mentioned publication is intended for small diameter pipes, and even if a heat retaining device and a cooling device are attached to the heating device in a replaceable manner,
It was not suitable to heat treat large diameter steel pipes such as UOE steel pipes with a diameter of 500 mmφ or more using any heat treatment pattern.

In other words, when heat treating a large diameter pipe of 500mmφ or more, the heat capacity of the pipe itself is large, so the length of each device (each unit) for heating, heat retention, and cooling must be long. In general, it is thought that the length is about 1 m per induction heating device, about 3 to 4 m per heat retention device, and several meters per cooling device. Therefore, the total length from the inlet of the heating device to the outlet of the cooling device is considered to be approximately 5 to 6 m or more. Note that when a large-diameter steel pipe such as such a UOE steel pipe is continuously heat-treated, the large-diameter steel pipe is generally conveyed and supported by a skew roller.

On the other hand, the standard length of UOE steel pipe is 12 m, but depending on the transportation method, it may be shortened to about 6 m. When transporting a pipe with a length of 12 m using skew rollers, if the spacing between the skew rollers is 6 m or less, the pipe material will always be supported by two or more skew rollers, but if the spacing between the skew rollers exceeds 6 m. In this case, a state in which the pipe material is supported by only one skew roller (single point support state; cantilever support state) occurs, causing the pipe material to be tilted and unable to be conveyed smoothly. Therefore, if the pipe length is 12 m, the spacing between the skew rollers must be within 6 m, and if the pipe length is shorter than that, the spacing between the skew rollers must be within 6 m.
It is necessary to make the spacing between the skew rollers even smaller than m.

However, as mentioned above, when applying to heat treatment of large diameter pipes, the distance from the inlet of the heating device to the outlet of the cooling device will be more than 5 to 6 m, so if there is no support in between, the above-mentioned There is a possibility that a single-point support state may occur, causing the pipe material to tilt and prevent it from being transported smoothly. Of course, it is not inconceivable to install skew rollers between each device to avoid the single point support situation described above, but the spacing between each device should be determined as much as possible from the standpoint of heat loss, etc. It is desirable to make the distance narrower, and therefore, in reality, it is necessary to avoid arranging skew rollers between each device.

This invention was made in view of the above-mentioned circumstances, and when a large-diameter steel pipe is heat-treated while being transferred by a skew roller in a UOE steel pipe manufacturing line, etc., a state where the large-diameter steel pipe is supported at one point occurs. As mentioned above, it is possible to easily and efficiently carry out a heat treatment pattern in which the temperature is maintained within a predetermined temperature range during the heating process before quenching, and also to easily and efficiently carry out various other heat treatment patterns. The purpose is to provide a highly versatile heat treatment system.

That is, the heat treatment equipment of the present invention includes two or more induction heating devices for rapidly heating the large-diameter steel pipe, along a transfer line that longitudinally transports the large-diameter steel pipe by a skew roller, and a heating device for heating the large-diameter steel pipe to a predetermined temperature. One or more heat retention devices for maintaining the large-diameter steel pipe at that temperature and a cooling device for cooling the heated large-diameter steel pipe are arranged in series, and at least one of the large-diameter A skew roller is disposed inside the device having the longest length in the steel pipe transfer direction, and each of the devices is installed so that the arrangement order in the large diameter steel pipe transfer direction can be changed. .

In such heat treatment equipment, the induction heating devices can be rearranged arbitrarily according to the required heat treatment pattern, and the heat treatment speed and holding time can be adjusted by adjusting the coil input of the induction heating device or the conveyance speed of large diameter steel pipes. can be changed in various ways by adjusting the
Therefore, in addition to heat treatment in which the steel is maintained within a predetermined temperature range during the heating process before quenching, it is possible to efficiently perform heat treatment in various patterns depending on the steel type and purpose. and two or more induction heating devices,
Of the one or more heat retention devices and cooling devices, the skew roller is installed inside the device (generally the heat retention device) that has the longest length in the direction of transport of large diameter steel pipes. In addition to the skew rollers, the skew rollers inside the equipment also support the large diameter steel pipes, so even if the overall length of the equipment is long and the large diameter steel pipes are short, the large diameter steel pipes must always be supported at two or more points. Therefore, it is possible to prevent the occurrence of a single point support state and to smoothly transfer the large diameter steel pipe. Furthermore, the heat treatment equipment is equipped with induction heating equipment and heat retention equipment arranged along the longitudinal transfer line of large diameter steel pipes, and performs induction heating and heat retention while transporting large diameter steel pipes in the longitudinal direction. because there is,
It is not necessary to cover the entire length of large-diameter steel pipes at once as in the case of batch type furnaces, and therefore a device with a relatively short overall length can be used, which is advantageous in terms of equipment costs and space factors.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an example of the arrangement when two induction heating devices 1 and 2 for rapid heating, one heat retention device 3, and one cooling device 4 are used.
The arrangement order of the large-diameter steel pipes 5 in the transfer direction A can be changed arbitrarily by lifting each of the devices 1 to 4 with a crane (not shown), or by lifting with a crane and moving using an appropriate drive device, etc. is set up. Of the two induction heating devices 1 and 2, the heat retention device 3, and the cooling device 4, the heat retention device 3, which has the longest length in the transfer direction A of the large-diameter steel pipe 5, has a section inside the heat retention device 3, which will be described later. As in the case shown in FIG. 9, a skew roller 14 (omitted in FIG. 1) is provided. Furthermore, although not shown, skew rollers are provided at the front and rear of the equipment (in front of the first guiding device 1 and behind the cooling device 4) as conveyance means for the large-diameter steel pipe 5, similar to the example shown in FIG. 9.

In the arrangement example shown in FIG. 1, the first induction heating device 1, the heat retention device 3, the second induction heating device 2, and the cooling device 4 are arranged along the transfer direction A of the large diameter steel pipe 5.
are arranged in that order. An example of such an arrangement is, for example, as shown in Figure 2, in the case of a heat treatment pattern in which a large diameter steel pipe is heated from room temperature, held at a certain temperature for a certain period of time, and then further heated and then cooled (for example, quenched). It is effective for Note that it is desirable to make the distance between each device 1 to 4 as small as possible in order to reduce heat radiation loss.

Further, to specifically explain the arrangement example shown in FIG. 1, the lengths of the induction heating devices 1 and 2 are each 1 m, the length of the heat retaining device 3 is 3 m,
If a predetermined coil input is applied to the induction heating devices 1 and 2 at a transfer speed of 1 m/min, the large-diameter steel pipe 5 is heated from room temperature to, for example, 500° C. by the first induction heating device 1, as shown in FIG. Rapidly raise the temperature and then hold it at 500°C for 3 minutes using a heat retainer 3,
Then, for example, 1000
A heat treatment can be performed in which the temperature is raised to °C and then cooled from that temperature. Here, since the holding time is given by (heat retaining device length)/(steel pipe transfer speed), any holding time can be obtained by adjusting the transfer speed.

Figure 3 shows an example of an arrangement in which the arrangement of each device in the equipment shown in Figure 1 is changed to maintain it at the maximum heating temperature. This can be obtained by widening the interval between the first induction heating device 1 and the heat retaining device 3 from the arrangement state shown in FIG. With this arrangement, the large diameter steel pipe 5 is heated to the maximum heating temperature while passing through the first and second induction heating devices 1 and 2, and then heated to the maximum temperature in the heat retention device 3. The temperature can be maintained and then cooled by the cooling device 4, so that the heat treatment can be carried out in a pattern as shown in FIG.

The heat treatment equipment for large-diameter steel pipes of this invention basically requires a heat retention device 3, but when actually using this heat treatment equipment, depending on the heat treatment pattern to be applied, the retention device 3 It can also be used with it removed. Examples of such cases are shown in FIGS. 5 to 8.

Here, FIG. 5 shows an example of the arrangement when heat treatment is performed in which there is no need to maintain a predetermined temperature and cooling is performed immediately after reaching the maximum heating temperature (i.e., the pattern shown in FIG. 6). It shows
In this case, the heat retaining device 3 is removed, and the first induction heating device 1 and the second induction heating device 2 are placed as close to the cooling device 4 as possible with the first induction heating device 1 and the second induction heating device 2 close to each other. In this case, when cooling immediately after rapid heating, if the capacity of the induction heating device is sufficient, only one induction heating device 1 or 2 is used as shown in Fig. 7, or conversely, if the capacity of the induction heating device is If even two heating devices are insufficient, another induction heating device 6 may be added as shown in FIG. Note that the heat retention device has been removed here, so
Even if another induction heating device 6 is added, there is no problem in terms of space.

Among the equipment arrangement examples shown in Figures 1, 3, 5, 7, and 8, the heat retention equipment has a long length in the direction of transport of large-diameter steel pipes. In the case of the arrangement example in which the apparatus 3 is incorporated, that is, in the case of FIG. 1 and in the case of FIG. 3, the total length of the heat treatment equipment is also 5.
~6m or more. Therefore, when transferring large diameter steel pipes using skew rollers, the distance between the skew rollers before and after the heat treatment equipment is 5 to 6 meters or more.
If the length of the large-diameter steel pipe 5 is short, when the large-diameter steel pipe 5 passes through the heat treatment equipment, it may come off either the front skew roller or the rear skew roller of the heat treatment equipment. However, as mentioned above, a skew roller is separately provided within the heat retaining device 3, and the large diameter steel pipe 5 is supported by the skew roller within the heat retaining device 3, so even if the large diameter steel pipe 5 is short, There is very little risk that the large-diameter steel pipe will become supported at one point and tilt while passing through the heat treatment equipment.

A more specific example of the heat treatment equipment of this invention is shown in FIG.

The heat treatment equipment shown in Figure 9 is a specific example in which the arrangement of each device is changed using a crane. In Figure 9, a large diameter steel pipe is held in the middle of heating, and The first induction heating device 1, the heat retention device 3, the second induction heating device 2, and the cooling device 4 are arranged in that order so that the temperature is raised to the maximum heating temperature and then immediately cooled down, that is, the first Figure 2 shows a state corresponding to the illustrated example.

In FIG. 9, a hanging handle 7 such as a hanging bolt is attached to the upper part of the induction heating devices 1, 2 and the heat retaining device 3 for hanging a wire when hoisting the devices 1, 2 with a crane. , 3 are placed on a pedestal 8. Skew rollers 11 are provided in front and behind the pedestal 8, respectively, for conveying the steel pipe. Each skew roller 11 is connected by a universal joint 12 and configured to be rotationally driven by a drive motor 13. And heat retention device 3
A skew roller 14 is also provided inside. Further, the cooling device 4 has a structure in which a cooling header 9 for uniformly spraying cooling water in the circumferential direction of the large-diameter steel pipe is covered with a removable cover 10.

In the example of the arrangement of heat treatment equipment shown in FIG. 9, the skew rollers 14 are provided inside the heat retaining device 3, so when considered together with the skew rollers 11 before and after the equipment, the spacing between the skew rollers is narrow. Therefore, even in the case of a relatively short large diameter steel pipe, it can always be supported by the skew rollers at two or more points.

Note that the heat treatment equipment shown in Figure 9 is also arranged in a heat treatment pattern (the pattern in Figure 6) that rapidly heats up to the maximum heating temperature without holding it during heating, and then immediately cools (quenches). A suitable sequence can be substituted. To explain the procedure in that case, in this case, first, as shown in FIG. let Next, as shown in FIG. 10B, the heat retaining device 3 is lifted up by a crane and placed outside the line, and then, as shown in FIG. 10C, while the first induction heating device 1 is lifted again by the crane 15, the second
close to the induction heating device 2. Thereafter, as shown in FIG. 10D, a temporary skew roller 11A is installed on the inlet side of the first induction heating device 1 and connected by a joint 2A to obtain an appropriate skew roller spacing.

On the other hand, the heat treatment equipment shown in FIGS. 11 to 14 shows an example in which each device is moved by a driving method.

11 and 12, a grooved jig 16 having a rail-shaped groove 15 along the steel pipe transfer direction is attached to the bottom of the induction heating devices 1, 2 and the heat retention device 3. Each device 1,
2 and 3 are placed on an elevating frame 17. This elevating frame 17 is raised and lowered by an elevating drive means (not shown), and is maintained at the raised position as shown in FIGS. 11 and 12 during normal operation, that is, during heat treatment. On the other hand, below the elevating frame 17 in the raised position, driving rollers 18 and non-driving rollers 19 are arranged at appropriate intervals at positions corresponding to the grooves 15 of the respective devices 1, 2, and 3. The drive roller 18 is driven by a motor 20 centered on an axis perpendicular to the steel pipe transfer direction.
These rollers 18, 19 and the elevating pedestal 17 are positioned so as not to interfere with each other when the elevating pedestal 17 is lowered. Furthermore, there are lifting hands 7 on the top of each device 1, 2, and 3 so that it can be lifted by a crane.
is installed. Furthermore, the heat retention device 3 is
Although not particularly shown, a skew roller is provided inside as in the case of FIG. 9.

When changing the arrangement of each device in the heat treatment equipment as described above, the elevating frame 17 is lowered as shown in FIGS. 13 and 14. In this way, the roller 1 is placed in the groove 15 at the bottom of each device 1, 2, 3.
8 and 19 are fitted, each device 1, 2, and 3 can be moved in the steel pipe transfer direction by driving the drive roller 18. It goes without saying that the crane 7 may also be used to rearrange the arrangement, for example by lifting the heat retaining device 3 and removing it out of the line as shown by the chain line in FIG.

As is clear from the above explanation, according to the heat treatment equipment of the present invention, when heat treating a large diameter steel pipe while conveying it using a skew roller, even when heat treating a relatively short large diameter steel pipe, the large diameter steel pipe Heat treatment of various patterns can be performed by changing the equipment arrangement according to the type of large-diameter steel pipe to be treated and the purpose of treatment, without causing a situation where the heat treatment equipment becomes supported at one point and tilts. Since it is a facility that continuously performs induction heating and heat retention while transporting large-diameter steel pipes in the longitudinal direction, the overall length of each device is relatively short.
It is also advantageous in terms of equipment costs and sparsity factors.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a first arrangement example of heat treatment equipment of the present invention, FIG. 2 is a diagram showing a heat treatment pattern according to the arrangement example of FIG. 1, and FIG. 4 is a diagram showing a heat treatment pattern according to the arrangement example of FIG. 3, FIG. 5 is a schematic diagram showing a third arrangement example of the heat treatment equipment of the present invention, and FIG. FIG. 5 is a diagram showing the heat treatment pattern according to the arrangement example, and FIGS. 7 and 8 are schematic diagrams showing still other arrangement examples for implementing the heat treatment pattern shown in FIG. 6, respectively.
FIG. 9 is a side view showing a specific example of the heat treatment equipment of the present invention, FIGS. A partially cutaway side view showing another specific example of the heat treatment equipment of the present invention, FIG. 12 is A of FIG. 11.
-A front view in the direction of arrow A; FIG. 13 is a side view corresponding to FIG. 11 showing the lowered state of the elevating platform in the equipment shown in FIGS. 11 and 12; and FIG. 14 is FIG. 13. FIG. 1, 2, 6...induction heating device, 3...heat retention device, 4...cooling device, 14...skew roller.

Claims (1)

[Claims] 1. Two or more induction heating devices for rapidly heating the large-diameter steel pipe and a large-diameter steel pipe heated to a predetermined temperature are installed along a transfer line for longitudinally transporting the large-diameter steel pipe by a skew roller. One or more heat retention devices for maintaining the temperature at that temperature and a cooling device for cooling the heated large diameter steel pipe are arranged in series, and at least one of these devices is arranged in a direction in which the large diameter steel pipe is transferred. A heat treatment facility for large-diameter steel pipes, characterized in that a skew roller is disposed inside the device having the longest length, and each of the devices is installed so that the arrangement order with respect to the transport direction of the large-diameter steel pipes can be changed. .