JPH0213479Y2 - - Google Patents

Description

[Detailed Description of the Invention] A. Field of Industrial Application The present invention relates to a pipe manufacturing device, and particularly to a pipe manufacturing device equipped with a solution treatment device.

B. Summary of the invention This invention is a pipe manufacturing equipment equipped with a solution treatment device consisting of a heating coil section for heating, a heat retention furnace, and a cooling section, in which the heat retention furnace is divided into multiple parts, and each heat retention furnace is separated. , can be connected freely, and at least one insulating furnace has an induction heating coil connected to a high-frequency or medium-frequency power source and a temperature control device, so that operations at different speeds (this is (Due to differences in the wall thickness of the heated material, etc.), the heat retention length can be changed to ensure sufficient diffusion and solid solution of the components of the heated material, and the temperature of the heat retention furnace can also be controlled accurately. It is possible to obtain high quality products.

C. Prior Art In a pipe manufacturing device that continuously makes pipes from strips, a long strip is conveyed at a predetermined speed, passed through a plurality of guide rolls, and gradually bent into a pipe shape. The edges are butted together using a squeeze roll, and the abutted portions are welded to form a pipe.

In the above-mentioned pipe manufacturing apparatus, when the material of the pipe to be manufactured is, for example, austenitic stainless steel (austenitic stainless steel pipe), heat treatment is performed with the main purpose of restoring the corrosion resistance of the welded part. Solution treatment is performed. Solution treatment is heating the pipe, which is the material to be heated, to a temperature of about 1100 to 1200℃, and keeping it at that temperature (approximately 1100℃ or higher) for a certain period of time (for example, 50℃).
100 seconds) to sufficiently diffuse and solidify carbon, etc. precipitated at grain boundaries, etc. within the crystal grains, and then rapidly cooled (water cooling, etc.).

The solution treatment apparatus may be an electric furnace or a burner furnace, or may be a high-frequency or medium-frequency induction heating coil. When an electric furnace or a burner furnace is used, heating → heat insulation → rapid cooling is performed while the material to be heated remains in the furnace, so there is no need for a heat retention furnace separate from the electric furnace or burner furnace. However, in the case of equipment that continuously manufactures pipes while moving the raw plate, it is required to carry out solution treatment while moving the pipe, and this requires the use of the above-mentioned high-frequency and medium-frequency induction heating coils. most suitable to use. In this case, it is necessary to provide a heat retention furnace separately from the heating coil.

A conventional pipe manufacturing apparatus equipped with a solution treatment apparatus using the above-mentioned induction heating coil will be explained with reference to FIG. This is the position where it will be carried out. The pipe material 1 is transported from left to right in the figure, and guide rolls 3 and 4 are arranged at a predetermined interval ahead of the welding position 2 (only in the moving direction). A solution treatment device 8 includes a heating coil section _{5 having an induction heating coil 51} between parts 3 and 4, a heat retention furnace 6, and a cooling part 7.
is provided. Then, the pipe material 1 to which both end edge abutting parts 1a of the stainless steel strip are welded at the TIG welding position 2 is heated and kept warm in the heating coil part 5 and the heat retention furnace 6, and then rapidly cooled in the cooling part 7. During these processes, the stainless steel is subjected to solution treatment. The heat-retaining furnace 6 is conventionally formed into a tunnel shape of a predetermined length using a heat insulating material, as shown in FIG.
It is connected to the outlet of the heating coil section 5 via a shield 10. Note that the cooling section 7 uses a water-cooled jacket in which cooling water is spouted from the inner periphery of an annular pipe.

D. Problems to be solved by the invention By the way, there have conventionally been two main problems to be solved regarding this heat-retaining furnace 6. The first is to keep the pipe 1 within a predetermined temperature range from the time it enters the furnace 6 to the time it leaves the furnace 6 while moving it, but this has not been possible. That is,
In order to obtain a product with high quality in terms of mechanical properties, structure, and corrosion resistance, it is necessary to ensure sufficient heat retention time to diffuse and dissolve carbon precipitated at grain boundaries into crystal grains. This can be done by making the heat retention furnace 6 longer, but on the other hand, if the heat retention furnace 6 is too long, the temperature of the pipe material 1 in the heat retention furnace 6 will drop and the temperature will not reach the appropriate temperature. It will be below the range. Especially the temperature just before cooling
When the temperature drops below 850°C, precipitation of chromium carbide becomes a problem, and in the case of a conventional heat-retaining furnace 6, as shown in Fig. 10, the temperature gradually drops as the pipe 1 moves inside the furnace, so it is simply a heat-retaining furnace. It was not possible to lengthen the furnace 6. On the other hand, if the heating temperature is set to 1200° C. or higher, the material to be heated becomes brittle, so it was impossible to unnecessarily raise the temperature to a high temperature and place the material in the insulating furnace 6. As described above, the problem of ensuring the desired heat retention time and heat retention temperature cannot be solved by changing the length of the heat retention furnace 6.

The second problem is that the heat retention length must be changed each time to ensure sufficient diffusion and solid solution of components for heated materials having different operating speeds. For example, if the pipe is thin, the transfer speed will be fast, so the required length of the insulating furnace will be longer (see Figure 11), but on the other hand, if the pipe is thick, the transfer speed will be slow, and its heat capacity will also be large. If the heat retention furnace is left for a long time, the heat retention time will become excessive and coarsening of crystal grains will occur.
(See Figure 2).

An object of the present invention is to provide a pipe manufacturing apparatus that solves the first and second problems described above.

E. Means for Solving Problems This invention bends and forms a steel strip plate into a pipe shape, welds the abutting parts of both edges, and uses a heating coil for heating to heat the welded pipe to solution treatment. , a pipe manufacturing apparatus equipped with a solution treatment device consisting of a heat retention furnace and a cooling section, wherein the heat retention furnace is divided into a plurality of parts in the direction in which the pipe travels, and at least one of the divided heat retention furnaces is equipped with a high frequency or medium frequency It is characterized in that it has an induction heating coil and a temperature control device connected to a power source, and that a plurality of heat retention furnaces and cooling parts are configured to be able to be separated and connected.

FIG. 1 is a basic principle diagram of the solution treatment apparatus 8 according to the present invention, in which the heating coil section ₅ has the same structure as the conventional one having high and medium frequency induction heating coils 51, ... is divided into a plurality of parts as seen in the direction of movement of the pipe, and each heat retention furnace 6a, 6
A... are constructed so that they can be connected and separated via a shield 10. Moreover, each heat retention furnace 6a, 6a...
Each of them has a heat insulating coil 6 _a1 consisting of a high-frequency induction heating coil and a medium-frequency induction heating coil, and also has a temperature control device (not shown). 6 _a2 is a high frequency or medium frequency power source. Furthermore, a cooling section 7a using a water-cooled jacket is disposed at the front of the most advanced heat-retaining furnace 6a when viewed in the direction of travel of the pipe.

According to the above configuration, each of the heat retention furnaces 6a, 6a... has a heat retention coil _6a1 and a temperature control device, and is connected by the shield 10, so that the inside of the heat retention furnace 6a can be maintained at a desired temperature and kept warm. The temperature from the inlet to the outlet of the furnace 6a can be maintained uniformly. Therefore, by increasing or decreasing the number of heat-retaining furnaces 6a, 6a, etc., the heat-retaining length can be freely set as shown in Fig. 2, which is optimal when the operating speed changes depending on the wall thickness of the pipe 1. It is best to choose the number of heating coils so that the heating time is 50 to 100 seconds. Moreover, in this way, the heat retention furnaces 6a, 6a...
The cooling section 7a is also structured to be movable in order to increase or decrease the temperature, so that the cooling section 7a can be disposed at the outlet of either the long or short heat insulating furnace 6a.

Further, a conventional heat-retaining furnace 6 may be incorporated between the induction heating type heat-retaining furnace 6a according to the present invention and the cooling section 7a, and the temperature distribution in that case will be as shown in FIG. 3.

F. Embodiment The present invention will be described below based on the embodiment shown in FIGS. 4 to 7. That is, FIG. 4 shows a case where the pipe 1, which is the material to be heated, is thin and moves at a high speed, and two heat retention furnaces 6 are installed in the heating coil section 5.
Fig. 5 shows an example in which pipes a and 6a are connected.
is thick and the moving speed is slow, and the heating coil part 5
An example is shown in which one insulating furnace 6a is connected to.

In each figure, the heating coil section 5 is installed on a movable frame 11 having wheels (not shown in the figures). A guide ring 12 is attached to one end of the movable frame 11 via a support portion 12a.
This guide ring 12 is used when passing through the plate, that is, when first inserting the pipe material 1 whose abutting portions of both edges are unwelded into the heat insulating furnace 6a.
This is a guide ring for guiding the pipe when passing through it, and has an inner diameter slightly larger than the outer diameter of the pipe after welding. Further, the heat-retaining furnace 6a is also installed on a movable pedestal 11 similar to that described above, and a guide ring 12 is provided at one end of the movable pedestal 11 via a support portion 12a. Each guide ring 12,
12 is embedded in a shield 10 of a predetermined length provided on each movable frame 11, 11, and the tip of the shield 10 is connected to the tip of the shield 10 extending from the other movable frame 11 at the position indicated by the connection line 13. Connected. In this way, one or more heat retention furnaces 6a can be detachably connected to the heating coil section 5.

Next, the cooling section 7a is constructed by attaching a water cooling jacket divided into left and right halves to the movable table 14. That is, as shown in FIGS. 6 and 7, in the cooling section 7a, the semicircular left and right members 15, which can be connected and separated at the connection section 16, are connected to an air pipe 15a provided on the insulating furnace side, respectively, and adjacent to the air pipe 15a. A water pipe 15b provided in the water pipe 15b jets cooling water toward the outer periphery of the pipe 1 from a small hole provided in the water pipe 15b, and a water pipe 15b is provided in the air pipe 15a. An air curtain is created by ejecting air toward the outer periphery, and the cooling water ejected from the water pipe 15b flows into the heat retention furnace 6.
a (located to the left in FIG. 6). In addition, 17 is a water pipe 15
Hose joint provided at b, 18 is air pipe 15a
This is a hose joint installed in the

Furthermore, in the cooling section 7a, 19 is a water collection tube that collects the cooling water spouted from the water pipe 15b. The water collecting tube 19 is formed by connecting a large number of tapered cylindrical members so as to be expandable and retractable, and its approximately middle portion is supported by a movable cart 20. At the rear end of this water collection tube 19, a water collection tank 21 is provided above a drainage hole (not shown), and the tip of the water collection tube 19 is configured to be able to be connected to a water pipe 15b in a watertight manner and detachable. . Since the water collecting cylinder 19 is supported by the movable cart 14 in this way, it is movable to an appropriate location, and is also expandable and contractible, so that the water collecting cylinder 19 can be moved to a suitable location, and can be expanded and contracted as shown in FIGS. 4 and 5.
Even if the number of units a increases or decreases, and therefore the installation position of the cooling unit 7a connected to the rear end of the heat retention furnace 6a changes,
The water collection tank 21 is installed at a predetermined location,
This can be dealt with by expanding and contracting the length of the water collection tube 19, and there is no need to move the concentration tank 21 connected to the drain port (fixed position) every time. In the cooling section 7a, the water pipe 15
The cooling water spouted from b toward the outer periphery of the pipe 1 flows through the water collection tube 19 and is collected in the water collection tank 21, thereby preventing it from scattering to the surroundings.

Note that the air pipe 15a and the water pipe 15b are divided into two parts, and when the plate is passed through, these parts are opened to the left and right, and the inside of the pipe material is expanded in a shape of a rubber band. Although it is stretchable, it is not a left-right split structure. However, since the water collection pipe 19 generally has a larger diameter than the water pipe 15b, it does not necessarily have to have a split structure.
After passing the pipe material through the water pipe 15b and closing it again, it can be easily passed into the water collection tube 19. According to this embodiment, each member of the solution treatment apparatus, especially the heat insulating furnaces 6a, 6a, the cooling section 7a, and the water collection tube 19, are movable by the moving cart, and therefore the pipe 1, which is the material to be heated, is movable. The operation of connecting and separating the heat retention furnaces 6a, 6a, . . . can be easily performed in response to changes in transfer speed due to differences in thick and thin walls.

G. Effects of the invention According to the invention, at least one insulation furnace is an induction heating insulation furnace, and by controlling the input power, the pipe material can be optimized during the entire insulation time required for the diffusion and solid solution of the components. It is now possible to maintain heat within the temperature range of This makes it possible to easily set the optimum heat retention time for the material to be heated. In particular, in solution treatment, the temperature and time of heat retention are greatly related to the mechanical properties and corrosion resistance of the heated material, but with the heat retention furnace of the present invention, the temperature and time of heat retention can be accurately controlled. This makes it possible to obtain products of excellent quality and also to increase production volume.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the principle of the solution treatment apparatus according to the present invention, Fig. 2 is a graph showing the temperature change of the pipe according to Fig. 1, and Fig. 3 is a diagram showing a heat retention furnace with a heating coil and a conventional heat retention furnace. FIG. 4 and FIG. 5 are side views showing two embodiments of the solution treatment apparatus according to the present invention, and FIG. 6 is a graph showing the temperature change of the pipe when combined. 7 is a front view of the cooling section, FIG. 8 is a plan view of a conventional pipe manufacturing device, and FIG. 9 is a cross-sectional view of a conventional solution treatment device and its heat retention furnace. Fig. 10 is a graph showing an example of the temperature change of the pipe according to Fig. 9, and Figs. 11 and 12 are graphs showing the conventional solution treatment of thin-walled and thick-walled pipes shown in Fig. 8 and Fig. 9, respectively. It is a graph showing an example of temperature change of a pipe when passing through a device. 1... Pipe, 5... Heating coil section, 6a...
Heat retention furnace, 7a...cooling section.

Claims (1)

[Scope of claims for utility model registration] (1) Continuously bending and forming a steel strip into a pipe shape,
In a pipe manufacturing apparatus equipped with a solution treatment device consisting of a heating coil section for heating, a heat retention furnace, and a cooling section for welding the butt portions of both edges and subjecting the welded pipe to solution treatment, the heat retention furnace The furnace is divided into multiple parts in the direction of pipe travel, and each furnace is configured to be connected and separated via a shield, and each divided furnace is connected to an induction heating coil connected to a high-frequency or medium-frequency power source. A pipe manufacturing device comprising a temperature control device and a plurality of heat retention furnaces and cooling sections configured to be separable and connectable. (2) The pipe manufacturing according to claim 1 of the utility model registration claim, characterized in that the cooling section has a two-part structure, has an air curtain on the insulating furnace side, and is constituted by a movable water cooling jacket. Device.