JPS6021384Y2 - Radiant tube heat treatment furnace - Google Patents

Description

[Detailed description of the invention] This invention is a vertical type radiation tube heat treatment method in which the material to be heat treated, such as a steel plate, is hung or stands up and is controlled, tempered, etc. without being moved laterally in the furnace. It is related to.

BACKGROUND ART So-called vertical furnaces have been widely known in the past, in which steel plates are suspended or made to stand up on their own and heat treated without being moved within the furnace.

However, in recent years, with the increase in the size of treated steel sheets, furnace heights reaching 6 meters have been required, so temperature non-uniformity in the height direction of the furnace due to buoyancy and convection has become noticeable. , it has become impossible to perform good heat treatment.

Therefore, a fan was installed in the hearth to stir the atmosphere inside the furnace, but in this case, the temperature around the fan impeller was 900%.
The temperature was as high as ~950°C, and the life of the fan was extremely short, posing a practical problem.

In this invention, radiant tubes are placed vertically in the heating zone where there are severe temperature changes, and radiant tubes are placed horizontally in the form of shelves in the soaking zone where temperature unevenness in the height direction is avoided, and a temperature control means is added. In this way, the temperature inside the furnace can be made uniform, high-quality heat treatment can be performed, and the life of the radiant tube can be maintained for a long time.The embodiment thereof will be explained with reference to the drawings.

1 to 4 show a first embodiment of the present invention, and a sixth embodiment of the present invention is shown in FIGS.
The figure also shows the second embodiment.

First, the overall configuration will be explained with reference to FIG.

A rectangular parallelepiped furnace is equipped with a charging door 1 at one end in the longitudinal direction and an extraction door 6 at the other end, with a ceiling insulation material 2 on the ceiling and a hearth insulation material 3 on the floor. A furnace shell 7 surrounds and holds them, and a large number of vertical radiant tubes 4 are installed in the heating zone, which is the charging side of the furnace, and a large number of horizontal radiant tubes 5 are installed in the soaking zone, which is the extraction side.
is inherent.

Next, the attachment of the vertical radiant tube 4 and the conveyance of the steel plate 12, which is the material to be heat treated, will be explained with reference to FIG.

The vertical radiant tube 4 is placed at an appropriate horizontal distance from the steel plate 12.
It passes through the ceiling heat insulating material 2, the hearth heat insulating material 3, and the hearth shell 7 in such a way as to sandwich the steel plate 12 therebetween, and is fixed to the ceiling by a fixing plate 11.

Further, a burner is provided at the lower end of the vertical radiant tube 4, and a seal between the furnace shell 7 and the vertical radiant tube 4 is provided by an extensible tube 9.

The steel plate 12 is attached to the banger device 1 installed on the ceiling.
It is suspended by 3.

Furthermore, the installation of the horizontal radiant tube 5 is in the third condition.
This will be explained with reference to the drawings and FIG.

A plurality of horizontal radiant pipes 5 are attached like shelves through the side wall insulation material 14 and the furnace shell 7, and in this embodiment,
As seen in FIG. 4, the horizontal radiant tube 5 has a U-shape, has a burner 8 at one end and is attached with a fixed plate 11, and the other end is attached and sealed with a telescopic tube 9. There is.

Further, as shown in FIG. 3, a plurality of thermocouples 15 are installed in the height direction through the side wall insulation material 14, and this temperature signal is inputted to the controller 16, and each burner 8 is provided with a plurality of thermocouples 15. A fuel supply pipe 18 is connected to each of them to send fuel as appropriate, and a flow rate adjustment valve 17 is provided in the middle of the pipe, so that the fuel supply can be increased or decreased based on instructions from the controller 16. .

In the radiation tube type heat treatment furnace configured in this way, the steel plate 12 suspended by the banger device 13 is placed at the charging door 1.
It enters the furnace and is heated by a group of vertical radiant tubes 4.

These vertical radiant tubes 4 themselves thermally expand and extend downward, but since they are sealed by the expansion tubes 9, there is no leakage to the outside of the gas furnace inside the furnace.

The area where the tube group of the vertical radiant tubes 4 is located is called a heating zone, and the steel plate 12 can be rapidly heated, and the temperature difference in the height direction within the furnace is of an allowable nature.

Furthermore, in this heating zone, the material temperature is low, as shown in the temperature curve diagram in FIG.
Although the thermal cycle that the tube undergoes is significant, since it is suspended vertically, there is no deflection due to the weight of the tube itself that occurs with horizontally placed radiant tubes, which is an ideal condition for a radiant tube, so its lifespan is short. It can be extended sufficiently for practical purposes.

Next, the steel plate 12 enters the soaking zone where the group of horizontal radiant tubes 5 is located.

Here, the temperature of the steel plate 12 has risen to near the heat treatment temperature, but as described above, since there is temperature unevenness, in this soaking zone, the temperature is slightly increased and the temperature is made uniform.

In this soaking zone, the temperature inside the furnace is measured by a plurality of thermocouples 15, and at a low temperature point, the flow rate control valve 17 can be opened according to instructions from the controller 16 to raise the temperature.

This controller 16 can control the temperature of the soaking zone in the height direction inside the furnace as desired.

In this soaking zone, as shown in FIG. 5, the temperature of the copper plate 12 and the set temperature in the furnace are very close, and the temperature change of the horizontal radiant tube 5 itself is very small, so there is little thermal expansion and contraction, so the horizontal radiant tube 5 There is no stress on the surface, and therefore, the lifespan will not be shortened even though the surface is level.

Note that the vertical axis t in FIG. 5 is temperature, and the horizontal axis X is the moving distance of the material, that is, time.

Further, in the figure, a is a heating zone, b is a soaking zone, and C is a set temperature in the furnace.

Furthermore, the curve d shows the temperature of the radiant tube in the heating zone, the curve e shows the temperature of the radiant tube in the soaking zone, and the curve f shows the material temperature (temperature of the steel plate 12).

FIG. 6 is a sectional plan view of a second embodiment of the present invention shown in correspondence with FIG. 4, and is an example in which the horizontal radiation tube 5 is L-shaped.

As mentioned above, according to the present invention, the radiant tubes are placed vertically in the heating zone where there are severe temperature changes, and the radiant tubes are placed horizontally in the form of shelves in the soaking zone where temperature changes are small but temperature unevenness is to be avoided. In addition to the arrangement, since a temperature control means is added, it is possible to equalize the temperature in the soaking zone and perform high-quality heat treatment, and the life of both the radiant tubes can be maintained for a long time, which is extremely advantageous. Become something.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional side view showing the first embodiment of the present invention;
The figure is an enlarged cross-sectional elevational view taken along section line A-A in Figure 1.
The figure is an enlarged cross-sectional elevational view taken along section line B-B in Figure 1.
The figure is a cross-sectional plan view taken along cutting line C-C in Figure 3, Figure 5 is a temperature curve diagram of the heat treatment furnace in Figure 1, and Figure 6 is a diagram showing the second embodiment of the present invention corresponding to Figure 4. FIG. 3 is a cross-sectional plan view of the embodiment. 1... Charging door, 2... Ceiling insulation material, 3... Hearth insulation material, 4... Vertical radiant pipe, 5... ...Horizontal radiant pipe, 6...Extraction door, 7...Furnace shell, 8...Burner, 9
...Extensible pipe, 10...Duct, 11.
... Fixed plate, 12 ... Steel plate, 13 ...
... Banger device, 14 ... Side wall insulation material, 1
5...Thermocouple, 16...Controller, 17...Flow control valve, 18...Fuel supply pipe.

Claims (1)

[Scope of utility model registration request] In vertical heat treatment, in which heat treatment is performed while holding the material to be heat-treated vertically and moving it laterally from a heating zone to a soaking zone, the heating zone is arranged so as to sandwich the material to be heat-treated at an appropriate horizontal distance. It consists of a group of vertical radiant tubes installed in
In addition, the soaking zone is made up of a group of horizontal radiant tubes installed along the flow of the material to be heat treated and arranged in a plurality of shelves in the height direction, and the group of horizontal radiant tubes includes a temperature control tube. A radiation tube heat treatment furnace characterized by being equipped with a device.