JP5200526B2 - Hot air heating furnace - Google Patents

Description

  The present invention relates to a hot air heating furnace used when, for example, a workpiece to be subjected to hot forging or the like is heated to a predetermined temperature.

Conventionally, for example, Patent Document 1 discloses a heating furnace for heating a workpiece to a predetermined temperature before performing hot forging, hot rolling, or the like on a metal material or performing a heat treatment on the metal material or the like. As described above, a so-called direct-fired heating method using a gas burner using natural gas, LNG or the like as a fuel has been proposed.
There has also been proposed a hot-air heating furnace that heats the workpiece charged in the furnace body by causing the high-temperature gas discharged from the gas burner to flow inside the furnace body.
JP 2006-284019 A

By the way, in the case of a direct-heating heating furnace, the temperature adjustment is performed by controlling the air-fuel ratio of the gas burner. However, if the air-fuel ratio slightly shifts, the length of the flame fluctuates. It is very difficult to regulate the temperature inside the body. In addition, if the flame becomes longer than necessary, the flame may directly touch the work inserted in the furnace body, and a part of the work may be locally heated.
In addition, when trying to make the temperature distribution uniform in the furnace body, it is necessary to arrange a plurality of gas burners and control the combustion state of the plurality of gas burners, and temperature adjustment is very difficult. .

On the other hand, in the above-described hot-air heating furnace, the gas burner is disposed at a position away from the work, so that the flame of the gas burner does not directly touch the work and a part of the work is locally heated. This can be prevented.
However, in the hot air heating furnace, the temperature is made uniform by flowing the hot gas inside the furnace body, and the work inserted in the furnace body and the structure inside the furnace to support the work are used. When the flow of the high temperature gas is hindered, a heat shield region where the high temperature gas does not flow may be formed. In this heat shield region, the temperature rise becomes slow, and it takes a lot of time to make the temperature distribution inside the furnace body uniform.

Here, for example, if a temperature distribution is generated in the workpiece during hot forging, the deformation resistance at the time of forging will be locally different, and accurate machining will not be possible. Further, in order to uniformly heat the workpiece, a lot of time is required to make the temperature distribution inside the furnace body uniform, and there is a problem that work efficiency such as hot forging is greatly reduced.
Furthermore, when trying to make the temperature distribution inside the furnace body uniform, it is conceivable to introduce hot gas from multiple gas inlets, but the flow of hot gas introduced from each gas inlet interferes with each other. Therefore, it was difficult to control the internal temperature of the furnace body.

  The present invention has been made in view of the above-described circumstances, and even when the flow of high-temperature gas is hindered by a work inserted into the furnace body or a structure in the furnace body, the work is made uniform and An object of the present invention is to provide a hot air heating furnace that can be heated early.

In order to solve this problem, the present invention proposes the following means.
A hot air heating furnace according to the present invention includes a furnace body provided with a gas introduction port, and gas introduction means for introducing a high temperature gas into the furnace body through the gas introduction port, and is installed in the furnace body. A hot air heating furnace that heats a workpiece that has been introduced, and a heat shield region in the furnace body in which a flow of high-temperature gas introduced from the gas inlet is blocked by the workpiece and the furnace body structure. An electric heating type auxiliary heat source is disposed in or near the heat shield region , the work is placed on the bottom surface of the furnace body, and the gas inlet is connected to the furnace body. The auxiliary heat source is provided at a lower portion of the one side wall portion provided with the gas introduction port .

In the hot air heating furnace having this configuration, electric heating is performed in or near the heat shield region formed by the flow of the high-temperature gas introduced from the gas inlet into the furnace body by the work or the furnace internal structure. Since the auxiliary heat source of the system is arranged, the temperature distribution inside the furnace body can be made uniform at an early stage by heating the heat shield area with this auxiliary heat source, and the work can be heated relatively uniformly. Can do. In addition, since the auxiliary heat source of the electric heating method is used, the output control of the auxiliary heat source can be performed relatively easily, and a part of the work can be prevented from being locally heated. Furthermore, the flow of the hot gas is not hindered by the auxiliary heat source, and the temperature distribution can be adjusted relatively easily.
Further, since the work is placed on the bottom surface of the furnace body, even a relatively large and heavy work can be easily carried into and out of the furnace body.
Furthermore, when high temperature gas is introduced from the gas inlet formed in the upper part of one side wall portion of the furnace body with the workpiece placed on the bottom surface of the furnace body, It flows along the side wall part which opposes. Here, the flow of the high-temperature gas is hindered by the workpiece, whereby a heat shield region is formed in the vicinity of the lower portion of the one side wall portion where the gas introduction port is formed. Therefore, the auxiliary heat source is disposed in the heat shield region by disposing the auxiliary heat source at the lower portion of the side wall portion where the gas inlet is provided. As described above, since the gas inlet and the auxiliary heat source are disposed on one side wall portion of the furnace body, no heat source is provided on the other side wall portion of the furnace body. The structure can be made relatively simple.

Here, it is preferable that the auxiliary heat source is configured to be provided on a wall surface of the furnace body.
In this case, since the auxiliary heat source is provided on the wall surface of the furnace body, the work and the auxiliary heat source do not interfere with each other when the work is loaded / unloaded, and the work loading / unloading work can be performed smoothly. Furthermore, damage to the auxiliary heat source can be prevented.

Furthermore, it is preferable that a temperature measurement unit is provided in the heat shield region, and a control unit is provided that adjusts the output of the auxiliary heat source according to the temperature measurement result by the temperature measurement unit.
In this case, the temperature of the heat shield region is actually measured by the temperature measuring means, and the output of the auxiliary heat source is adjusted by the control unit according to the temperature measurement result, so that the furnace body internal temperature can be further uniformized. .

  According to the present invention, even when the flow of high-temperature gas is hindered by the workpiece inserted into the furnace body or the structure inside the furnace body, the warm air that can heat the workpiece uniformly and quickly A heating furnace can be provided.

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 3 show a hot air heating furnace according to an embodiment of the present invention.
The hot air heating furnace 10 according to this embodiment heats the metal material (work W) to a predetermined temperature before hot forging the metal material (work W) such as a Ni-base heat-resistant alloy. It is used when.

The hot air heating furnace 10 includes a furnace body 20, a gas burner 30 for introducing a high-temperature gas into the furnace body 20, and a support member 14 (in-furnace structure) for supporting the workpiece W. I have.
The furnace body 20 has a multilayer structure of refractory bricks and heat insulating bricks, and includes a bottom surface portion 21, a top surface portion 22, and a side wall portion 23.
A gas inlet 24 for introducing a high temperature gas into the furnace body 20 is provided on the upper side of the one side wall portion 23A.

  The gas inlet 24 is provided with a gas burner 30 using natural gas, LNG or the like as fuel. In this embodiment, as shown in FIG. 2, three gas burners 30 are arranged in parallel at the same height portion of one side wall portion 23A. As shown in FIG. 1, the gas burner 30 is configured to discharge the high temperature gas toward the other side wall portion 23 </ b> B facing the one side wall portion 23 </ b> A, and the high temperature gas discharged from the gas burner 30. Flows along the bottom surface portion 21 of the furnace body 20 and flows toward the bottom surface portion 21 at the other side wall portion 23B facing the one side wall portion 23A.

As shown in FIG. 3, a gas supply means 31 for supplying fuel gas and an air supply means 32 for supplying combustion air are connected to the gas burner 30 via valves 33 and 34, respectively. These valves 33 and 34 are opened and closed by a burner combustion control unit 35 so that the air-fuel ratio of the gas burner 30 is adjusted.
Here, in the present embodiment, the first thermocouple 11 for measuring the temperature in the furnace is inserted into the top surface portion 22 of the furnace body 20, and the burner combustion control unit 35 is connected to the first thermocouple 11. The air-fuel ratio of the gas burner 30 is adjusted according to the measurement result. The data of the first thermocouple 11 is sequentially recorded on the recorder 13.

  In addition, a support member 14 (in-furnace structure) for supporting a workpiece W described later is disposed on the bottom surface portion 21 of the furnace body 20. In the present embodiment, as shown in FIGS. 1 and 2, the support member 14 protrudes upward from the bottom surface portion 21, and extends from one side wall portion 23 </ b> A to the other side wall portion 23 </ b> B along the bottom surface portion 21. It is composed of two rails extending toward the front.

In the present embodiment, the workpiece W to be heated is made of a metal such as a Ni-base heat-resistant alloy and has a substantially cylindrical shape. As shown in FIG. 1, such a workpiece W is placed on the support member 14 so that the two workpieces W are arranged in parallel. Specifically, it is placed so that the axis of the cylinder formed by the workpiece W is orthogonal to the extending direction of the indicating member.
In this embodiment, the workpiece W is placed on the bottom surface portion 21 as described above, and is discharged from the gas burner 30 to the bottom surface portion 21 and the other side wall portion 23B of the furnace body 20 as shown in FIG. The hot gas flow toward the bottom surface portion 21 is blocked by the work W, and a heat shield region C in which the high temperature gas hardly flows is formed near the lower portion of the one side wall portion 23A.

  An electric heater 40 is disposed in a lower portion of one side wall portion 23 </ b> A where the heat shield region C is formed, that is, in a lower portion of the gas inlet 24. The electric heater 40 is configured by hanging a heater element 42 on a hanger pin 41 protruding from one side wall portion 23A, and the heater element 42 generates heat when energized.

  Here, a second thermocouple 12 for measuring the temperature of the heat shield region C formed in the furnace is inserted below the one side wall portion 23A. A heater control unit 43 that controls the amount of current supplied to the heater element 42 according to the measurement result of the thermocouple 12 is connected. The measurement results of the second thermocouple 12 are sequentially recorded in the same recorder 13 with the first thermocouple 11.

In the hot air heating furnace 10 having such a configuration, the two workpieces W are placed on the support member 14 provided on the bottom surface portion 21 as described above. And the gas burner 30 arrange | positioned at the gas inlet 24 is burned, and high temperature gas is introduce | transduced in the furnace body 20 inside. As described above, the introduced high-temperature gas flows inside the furnace body 20, but the flow of the high-temperature gas is blocked by the workpiece W placed on the support member 14, and the heat-shielding region C is formed. It is formed. The heat shield region C is heated by an electric heater 40 disposed on one side wall portion 23A.
In this way, the inside of the furnace body 20 is heated by the high-temperature gas and the electric heater 40, so that the workpiece W rises to a predetermined temperature, and the workpiece W is supplied to the hot forging process, which is a subsequent process. .

  According to the hot air heating furnace 10 according to the present embodiment, the work body W blocks the flow of high-temperature gas introduced into the furnace body 20 from the gas burner 30 disposed in the gas introduction port 24, so that the furnace body. Although the heat shield region C is formed inside 20, the electric heater 40 is provided as an auxiliary heat source below the one side wall portion 23A located in the heat shield region C. By heating with the heater 40, the workpiece | work W can be heated comparatively uniformly and at an early stage. Further, since the electric heater 40 is provided as an auxiliary heat source, the flow of the high-temperature gas introduced from the gas introduction port 24 is not hindered, and the interior of the furnace body 20 can be heated uniformly.

  In addition, since the electric heater 40 is disposed on the one side wall 23A, the work W and the electric heater 40 do not interfere with each other when the work W is loaded and unloaded, and the work W can be loaded and unloaded smoothly. Can be done. Further, by preventing contact between the workpiece W and the electric heater 40, the life of the electric heater 40 can be extended.

  Furthermore, since the workpiece W is placed on the bottom surface portion 21 of the furnace body 20, even if the workpiece W is relatively large and heavy, the workpiece W can be easily carried into and out of the furnace body 20. Can do. In addition, the gas inlet 24 is formed in the upper part of the one side wall part 23A, and the electric heater 40 is provided in the lower part of the one side wall part 23A, so that a heating source is provided in the other part of the furnace body 20. This is not necessary, and the structure of the hot air heating furnace 10 can be made relatively simple.

In the present embodiment, the first thermocouple 11 for measuring the temperature in the furnace is inserted in the top surface portion 22 of the furnace body 20, and the gas burner 30 has a gas burner 30 according to the measurement result of the first thermocouple 11. Since the burner combustion control unit 35 for adjusting the air-fuel ratio is provided, the internal temperature of the furnace body 20 can be controlled with high accuracy.
Further, the second thermocouple 12 is inserted in the heat shield region C, and a heater control unit 43 that controls the energization amount to the heater element 42 according to the measurement result of the second thermocouple 12 is disposed. Therefore, the output of the electric heater 40 can be adjusted according to the temperature of the heat shield region C, and the internal temperature of the furnace body 20 can be further uniformized.
In the present embodiment, since the measurement results of the first thermocouple 11 and the second thermocouple 12 are recorded in the same recorder 13, the internal temperature of the furnace body 20 including the heat shield region C is timed. It becomes possible to confirm the change.

As mentioned above, although embodiment of this invention was described, this invention is not limited to this, It can change suitably in the range which does not deviate from the technical idea of the invention.
For example, before performing hot forging on a metal material (work) such as a Ni-base heat-resistant alloy, it has been described as being used when heating the metal material to a predetermined temperature, but it is limited to this. Instead, it may be used in a heating furnace for performing a heat treatment on a metal material (workpiece).
Moreover, there is no limitation in the shape etc. of a workpiece | work, You may insert and heat the workpiece | work of arbitrary shapes in the furnace body inside.

  Furthermore, although it has been described that a gas burner is disposed directly at the gas inlet, the present invention is not limited to this, and the gas burner is burned in a gas chamber provided separately from the furnace body and obtained in this gas chamber. It is good also as a structure which introduces the obtained high temperature gas into the inside of a furnace body via a gas inlet. Furthermore, you may use the waste gas discharged | emitted from another installation as high temperature gas, without using a gas burner.

  In addition, the electric heater has been described as having a structure in which a heater element is hung on a hanger pin protruding from one side wall portion, but is not limited to this. For example, a detachable electric heater unit is provided. It is good also as a structure mounted in the bottom face part of a furnace body.

Below, the result of the comparative experiment performed in order to confirm the effectiveness of this invention is demonstrated.
As an example of the present invention, a cylindrical workpiece having a diameter of 360 mm and a length of 1900 mm is heated by a hot gas introduced from a gas burner and an electric heater provided on a side wall using the hot air heating furnace described in the embodiment. did. At this time, the measurement temperature of the thermocouple (second thermocouple) inserted in the heat shield region formed by blocking the flow of the high temperature gas by the work was recorded. The target temperature (lower limit) in the furnace was set to 785 ° C.

  As a conventional example, a cylindrical workpiece having a diameter of 360 mm and a length of 1900 mm was heated only by a high-temperature gas introduced from a gas burner, using the hot air heating furnace described in the embodiment. At this time, the measurement temperature of the thermocouple (second thermocouple) inserted in the heat shield region formed by blocking the flow of the high temperature gas by the work was recorded. The target temperature (lower limit) in the furnace was set to 785 ° C.

The result of this comparative experiment is shown in FIG.
As shown in FIG. 4, according to the conventional example using no electric heater, it was confirmed that the temperature of the heat shield region reached 785 ° C., which is the target temperature (lower limit), after 220 minutes from the start of heating. That is, at least 220 minutes of heating is necessary to perform hot forging.
On the other hand, according to the example of the present invention using an electric heater, it was confirmed that the temperature of the heat shielding region reached 785 ° C., which is a target temperature (lower limit), after 42 minutes from the start of heating.
That is, according to the example of the present invention, it was confirmed that the heating time can be significantly reduced as compared with the conventional example.

It is sectional drawing of the warm air heating furnace which is embodiment of this invention. FIG. 2 is a cross-sectional view taken along the line XX shown in FIG. 1. It is a system block diagram of the warm air heating furnace which is embodiment of this invention. It is a graph which shows the result of an Example.

Explanation of symbols

10 Hot air heating furnace 12 Second thermocouple (temperature measuring means)
14 Support member (in-furnace structure)
20 furnace body 23 side wall part 24 gas introduction port 30 gas burner (gas introduction means)
40 Electric heater (auxiliary heat source)
43 Heater control unit (control unit)

Claims (3)

A hot air heating system comprising a furnace body provided with a gas introduction port, and gas introduction means for introducing a high temperature gas into the furnace body through the gas introduction port, and heating a workpiece charged in the furnace body A furnace,
Inside the furnace body, there is formed a heat shield region in which the flow of the high-temperature gas introduced from the gas inlet is blocked by the work and the furnace body structure, in the heat shield region or the vicinity thereof, An electric heating type auxiliary heat source is provided,
The workpiece is placed on the bottom surface of the furnace body, and the gas introduction port is formed on an upper portion of one side wall portion of the furnace body,
The hot air heating furnace , wherein the auxiliary heat source is provided in a lower portion of the one side wall portion provided with the gas introduction port .   The warm air heating furnace according to claim 1, wherein the auxiliary heat source is provided on a wall surface of the furnace body. A temperature measuring means is disposed in the heat shield region,
The hot air heating furnace according to claim 1 or 2, further comprising a control unit that adjusts an output of the auxiliary heat source according to a temperature measurement result by the temperature measuring means.

Images