JP2020176816A - Circulation type electric furnace - Google Patents

Abstract

To provide a circulation type electric furnace capable of cooling a heated product 4 at a constant cooling rate by taking in outside gas.SOLUTION: A circulation type electric furnace of this invention comprises the following components arranged in series: a propeller fan 9 for circulating gas in the closed circulation type electric furnace; a circulation motor 4 for rotating the propeller fan; a heat generator 5 for heating the wind generated; and a plate body 13 that rotates for taking in gas from outside.SELECTED DRAWING: Figure 1

Description

The present invention relates to a series circulation electric furnace.

A furnace body capable of heating and cooling an object to be heated using hot air is described in Patent Document 1, Patent Document 2, and Patent Document 3, in which a cooling path connected in parallel to the main circulation path for cooling is provided. The cooling rate is controlled by switching the path with a damper or changing the damper angle.

JP 2017-12154 JP-A-2007-27126 JP 2000-329474

There is a reverberatory furnace as a method of heating an object to be heated at high speed and cooling it at the same time.
The reverberatory furnace does not heat the inside of the furnace body, and the heat of the heating element can be directly applied to the object to be heated.
However, heat absorption differs depending on the reflectance of the surface of the object to be heated.
Absorption of heat rays from heating elements differs between black bodies such as charcoal and polished aluminum.
Therefore, a temperature difference occurs and it becomes difficult to obtain accurate data.

Further, in the heating method using a hot plate in which a heating element is placed under the plate and an object to be heated is placed on the plate, a temperature difference occurs depending on the degree of contact between the heated surfaces and a difference between the temperature of the surface that does not contact the hot plate. Therefore, the temperature is not uniform even on the object to be heated.

For the reasons mentioned above, in the case of the reverberatory furnace and in the case of hot plate heating, a large temperature difference occurs in the object to be heated.
In the present invention, a temperature-controlled hot air is used as a medium to heat an object to be heated.
A heating element, a fan for circulating the gas heated by the heating element, a circulation path for guiding the heated gas to the object to be heated, rotating or rotating or taking in a gas having a temperature lower than the inside of the furnace body from the outside. By using a sliding plate, the structure is such that the amount of exhaust and intake can be controlled.
The above elements are arranged in series.
Changing the order of the components does not deviate from the gist of the present invention.

The heating element generates heat by Joule heat by applying a voltage to the heating element using a nichrome wire or the like. At this time, the circulating gas is heated by touching the heated heating element, and the heated gas is circulated in the furnace by a fan installed in the path.
By controlling the calorific value, the temperature is adjusted to a desired temperature.
It is also possible to raise the temperature at a constant speed or hold it at a predetermined temperature.

In the present invention, an intake port and an exhaust port are provided in the path of the circulation type electric furnace, and outside air is introduced to cool the object to be heated and the furnace body.

Further, in this cooling mechanism, the object to be heated can be cooled at a desired cooling rate by controlling the angle of the plate body.
It is structurally simple, and by changing the rotation angle of one rotating shaft, gas is taken into the circulation path from the outside and cooled.

Since the heating element, the object to be heated, the propeller fan for circulation, the intake port, and the exhaust port are arranged in series, the response is quick, the number of parts is small, and it can be manufactured at low cost.
Further, since the number of components in the furnace is small, the heat capacity is also small, and the target temperature set in the temperature control program can be quickly given from the heating element to the object to be heated.

As a method of opening, the method described in the present invention describes a method of opening the exhaust port and the intake port at the same time as closing the circulation path by the plate body.
However, the opening areas of the exhaust port and the intake port do not have to be the same. It is also possible to configure the intake port and the exhaust port with separate plates.

Detailed description of the invention

FIG. 1A is a side sectional view of a series circulation type electric furnace. FIG. 1B is a rear view.
The gas circulates in the circulation path 16 which is a closed pipe-like space surrounded by the external heat insulating wall 1, the internal heat insulating wall 2, and the side heat insulating wall.
After the object 8 to be heated is placed on the net 10, the door 9 is closed to form a closed pipe-shaped space.

The gas circulates through the gaps between the circulation path 16 and the net 10.
The circulation fan motor 4 rotates the propeller fan 3 attached to the rotating shaft to create a gas flow in the direction of the wind direction 11a.

Since the place where this gas is located is in a closed circulation path, the gas flow circulates from the wind directions 11a to 11b, 11c, 11d, 11e as shown by the arrows, is accelerated again by the propeller fan 3, and circulates in the circulation path. To do.
This gas flow is heated by passing through a heating element 5 installed in the path.
The heating element 5 generates heat due to Joule heat by applying a voltage to the heating element lead wire 6.

The gas passes through the heating element 5, and if a voltage is applied to the heating element lead wire 6 at this time, the temperature rises.
A temperature sensor 7 placed in the middle of circulation detects the temperature of this heated gas.
The detected temperature is converted into an electric signal and output to the controller.
The controller creates a voltage signal for controlling the heating element 5 from the input temperature information. This voltage signal is applied to the heating element 5 through the heating element lead wire 6 to heat the heating element 5.
Further, the gas whose temperature has risen heats the object 8 to be heated. Further, it passes through the net 10 and is reaccelerated by the propeller fan 3.

By repeating the above operation, the gas circulates in the circulation path 16.
The propeller fan 3 can be replaced with a centrifugal fan, a sirocco fan, or the like, and if necessary, the air volume corresponding to the object to be heated 8 can be changed by changing the rotation speed of the circulation fan motor 4.

When lowering the temperature, gas is taken in from the outside. In the side sectional view of FIG. 1, the amount of gas taken in from the outside can be changed by changing the angle of the plate body 13.
In FIG. 1, the plate body 13 is arranged in parallel with the circulation path as shown in FIG. 1, and can flow the gas without interfering with the circulation of the gas in the circulation path 16. At this time, there is no exhaust or intake of external gas.

In FIG. 1 (c), when the plate body 13 rotates the plate body 13 in the rotation direction of the clock from the state of FIG. 1 (a) and becomes an angle as shown in FIG. 1 (c), some gas is discharged to the outside. It is discharged and the remaining gas circulates in the circulation path 16.
At this time, the gas in the furnace is discharged in the directions of the wind direction 12c and the wind direction 12d.
At the same time, since the circulation path 16 is sealed except for this opening, the same amount of external gas as the gas discharged in the directions of the wind direction 12a and the wind direction 12b is sucked in so as to maintain the internal air pressure.
The rotation angle of the plate body 13 is determined by the controller reading the electric signal from the temperature sensor 7 and calculating the rotation angle so as to reach the desired optimum temperature.
When the temperature is raised, electric power is supplied to the heating element 5, and when the temperature is lowered, the plate 13 is rotated clockwise.

As a result of the calculation, the calculated angle is sent to the stepping motor 17 by a signal from the controller, transmitted to the rotating shaft 18 so as to have a desired angle, and the plate body 13 attached to the rotating shaft 18 rotates. To do.
The stepping motor 17 can be replaced with a servo motor or the like.

In addition, this function is in the circulation path 16 in order to quickly match the actual furnace temperature to the target temperature when the target temperature in the temperature program suddenly decreases and the actual temperature becomes higher than the target temperature. It is also effective for lowering the temperature of.
In a furnace body with high heat insulation performance, it is usually not possible to have an effective cooling means.

Further, when the plate body 13 is rotated clockwise and the plate body 13 is moved to the horizontal state as shown in FIG. 3, all the gas inside is discharged.
At the same time, the same amount of gas is inhaled from the outside.
Although the temperature cannot be controlled at the position of the plate body 13, the inside of the furnace body can be cooled to the maximum, and at the same time, the object to be heated 8 can be cooled.

When the power is turned on, if the plate body 13 is stopped at an intermediate angle as shown in FIG. 1 (c), the plate body 13 is rotated 90 degrees counterclockwise.
The plate body 13 abuts against the stopper 15 in the middle of rotation, but at this time as well, the plate body 13 is further rotated, and the rotational current is continuously applied so that the total becomes 90 degrees.
The stepping motor 17 and the plate body 13 are mechanically locked, but the stopper 15 and other mechanical parts are designed to have sufficient proof stress against the force generated by the stepping motor 17, and the stepping motor 17 is used having sufficient yield strength so that the coil of the stepping motor 17 does not burn out or other failures occur even if the locked state continues.
The origin of the position of the plate 13 can be easily set by such a method.

Instead of using the stopper 14 and the stopper 15, there is also a method of detecting and controlling the position of the plate body 13 by light or magnetism.

Next, an example using two rotating plate bodies 21 and a plate body 22 will be described.
FIG. 2A shows a state of the plate body 21 and the plate body 22 whose temperature is rising.
This is the same state as in FIG. 1 (a).
At this time, the plate body 21 and the plate body 22 do not affect the gas flow path at all.
In FIG. 2B, when the two plate bodies 21 and the plate body 22 rotate from the vertical position and the plate body 21 and the plate body 22 have an angle as shown in FIG. 2B, the circulation path 16 is established. A part of the flowing gas is discharged to the outside like the wind direction 24. At the same time, the same amount of gas is sucked in from the outside like the wind direction 25.
In FIG. 2C, when the plate body 21 and the plate body 22 are further held in parallel as shown in the figure, all the gas flowing through the circulation path 16 is discharged to the outside.
At the same time, the same amount of gas is sucked from the upper part of the plate 22 in the direction of the wind direction 25.
In this way, an external gas can be taken into the circulation path 16.
Here, the mixing prevention plate 23 is installed for the purpose of preventing the exhausted gas from being taken into the adjacent intake port and deteriorating the efficiency.

In FIG. 3A, exhaust is performed using the pressure in the circulation path 16.
This is a method of pushing the exhaust port plate 33 apart by the wind pressure created by the propeller fan 3.
In FIG. 3C, the plate body 31 blocks the flow path of the circulation path 16.
Therefore, at the lower part of the plate body 31, the wind pressure is increased by the propeller fan 3 and the exhaust port plate body 33 is pushed open.
In this way, the gas circulating in the circulation path 16 is discharged to the outside.
By exhausting, the air pressure in the circulation path 16 decreases.
Therefore, the intake port plate 32 opens the outside air so as to replenish the lowered air pressure, and takes in gas from the outside.

Here, the intake port plate body 32 and the exhaust port plate 33 are in the state shown in FIG. 3A due to their own weight when no external force is applied. When the plate body is placed parallel to the flow path, the wind pressure that pushes the plate body away is not generated, so that the intake port plate body 32 and the exhaust port plate 33 do not have an effect of taking in external gas into the circulation path 16. .. The feature of this method is that it does not require a motor that gives rotation to the intake port plate 32 and the exhaust port 33 from the outside, which is convenient.
FIG. 3 (b) is located between FIGS. 3 (a) and 3 (c), and the exhaust is also moderate.

Although the description described here is to change the opening area for the rotating type plate, it is easy to increase or decrease the number of plates to obtain the same effect.
Further, it is easy to imagine that a slide type plate is used instead of the rotation type, and the opening area is changed by sliding the plate to obtain the same effect.

A basic circulation furnace configuration diagram with a singular plate. Circulation furnace configuration diagram with multiple plates. Circulation furnace configuration diagram using wind pressure.

1 Outer insulation wall 2 Inner insulation wall 3 Propeller fan 4 Circulation fan motor 5 Heater 6 Heater lead wire 7 Temperature sensor 8 Heated object 9 Door 10 Net 11a Wind direction 11b Wind direction 11c Wind direction 11d Wind direction 11e Wind direction 12a Wind direction 12b Wind direction 12d Wind direction 13 Plate 14 Stopper 15 Stopper 16 Circulation path 17 Stepping motor 18 Rotating shaft 21 Plate 22 Plate 23 Mixing prevention plate 24 Wind direction 25 Wind direction 31 Plate 32 Intake port plate 33 Exhaust port plate 34 Wind direction 35

Claims (1)

In a gas circulation type electric furnace where gas circulates in the duct and can heat the object to be heated,
A heater that can control electric power and
With a fan that circulates gas,
The exhaust of the gas inside the furnace to the outside and the plate body that controls the intake of the outside gas into the furnace by rotating or sliding are
Electric furnace installed in series.

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