JP2019100697A - Circulation type electric furnace - Google Patents

Abstract

To provide a circulation type electric furnace capable of cooling a to-be-heated object to be heated at a fixed cooling velocity by taking-in the outside gas.SOLUTION: Provided is an electric furnace where a gas is circulated in a duct 6, comprising: a suction port 19 having one or more opening/closing means; and an exhaust port 23 having one or more opening/closing means, in which a heater unit 11, a gas permeable mounting part and a fan 7 are arranged in the process of a circulation passage, comprising means where, by changing the opening areas of the suction port 19 and the exhaust port 23, the gas at the outside of an electric furnace is taken in, and a to-be-heated object 4 is cooled at a desired cooling velocity.SELECTED DRAWING: Figure 1

Description

   The present invention relates to a circulation type electric furnace in which gas circulates in a circulation duct.

Various electric furnaces are used as a heating method of the to-be-heated material using a furnace. Its applications are wide-ranging such as temperature control at high speed for quality control etc., data acquisition of a large amount of expansion rate in a short time, adhesion of products at manufacturing site, soldering, promotion of chemical reaction, etc.
Patent Documents 1 to 3 describe furnaces capable of rapidly raising and decreasing the temperature, in which a refrigerator is used.

There is a radiant electric furnace as a furnace that can raise the temperature at high speed. In the case of a radiant electric furnace, high speed heating is possible. However, the amount of heat transferred from the furnace heating portion to the object to be heated differs depending on the reflectance of the surface of the object to be heated. Therefore, a temperature difference tends to occur on the object to be heated.
For the above reason, there is a drawback that the temperature can not be accurately measured unless the temperature sensor for detecting the temperature is in close contact with the object to be heated.
When the object to be heated is a metal other than a metal with high electrical conductivity such as copper, aluminum, silver, etc., a thermocouple is spot-welded to the object to be heated, or in the case of other substances, heat resistant adhesive or the like. The work of bonding the object to be heated and the temperature sensor occurs, which is complicated.
At the time of cooling, the heater of the radiant electric furnace is turned off and it is cooled by natural heat radiation.

On the other hand, in a circulation type electric furnace in which a heated gas having a temperature equal to the target temperature is circulated, heating does not affect the reflectance of the surface of the object to be heated because it is heated by conduction through the gas.
Therefore, merely setting the temperature sensor in the vicinity of the object to be heated hardly causes a temperature difference between the object to be heated and the temperature sensor. However, in a circulation type electric furnace in which a gas circulates in a thermally insulated space, it is difficult to lower the temperature faster than the natural cooling rate at which the inside of the furnace naturally cools after the heater is turned off.
In addition, when a phenomenon called overshoot occurs in which the actual temperature is higher than the target temperature due to the disturbance of the temperature control, there is no way but to wait for the temperature to decrease due to natural cooling.
In particular, a furnace with better heat insulation performance takes longer time to cool, which is a factor to deteriorate the temperature control performance at the time of cooling.

JP, 2017-120154, A Japanese Patent Application Laid-Open No. 11-57580 Japanese Utility Model Application Publication No. 63-152679

  SUMMARY OF THE INVENTION In view of the above problems, the present invention is capable of taking in surrounding gas lower than the temperature in the furnace and obtaining a constant cooling rate in a circulating electric furnace, and using a heated gas close to a target temperature An object of the present invention is to provide a heating method in which it is not necessary to attach a thermocouple or the like which is a temperature sensor to a substance to be heated by heating the substance to be heated.

  In order to solve the above-mentioned problems, the present invention is an electric furnace in which gas circulates in a duct, comprising: an intake port having one or more opening and closing means; and an exhaust port having one or more opening and closing means The heater unit, the air-permeable mounting portion, and the blower are disposed in the middle of the chamber, and by changing the opening area of the intake and exhaust ports, the gas outside the electric furnace is taken in and the object to be heated is cooled at a desired cooling rate. Adopt means to cool the

  Further, the present invention adopts a means in which the intake port is provided downstream of the permeable mounting portion and upstream of the blower, and the exhaust port is provided downstream of the blower and upstream of the permeable mounting portion. obtain.

  Furthermore, the present invention may employ a means in which the intake and exhaust ports are provided downstream of the blower and upstream of the air-permeable mounting portion.

  Still further, the present invention may employ means in which the air intake and exhaust are provided adjacent to each other.

  Furthermore, according to the present invention, the opening and closing means at the intake port and the opening and closing means at the exhaust port are integrally constituted by a single plate body, and the plate body has a rotary shaft at its substantially central portion and is adjacent It is possible to employ a means for pivoting around the boundary between the intake and exhaust ports.

  Still further, according to the present invention, the opening / closing means in the air inlet is constituted by a first plate, the opening / closing means in the exhaust port is constituted by a second plate, and the first plate is an end The second plate has a rotating shaft at its end and has a downstream boundary between the duct and the exhaust port. A pivoting means may be employed.

Further, according to the present invention, the air inlet or the exhaust port is provided with a means for increasing or decreasing the pressure, and by changing the pressure for increasing or decreasing the pressure together with the opening area of the inlet and the exhaust port A means for taking in the gas and cooling the object at a desired cooling rate may be employed.

  According to the circulation type electric furnace according to the present invention, natural cooling is performed by taking in a gas having a temperature lower than the temperature in the furnace from the intake port into the circulating furnace and discharging the gas in the furnace heated from the exhaust port. The temperature can be lowered faster than in the case of

  Further, according to the circulation type electric furnace according to the present invention, by controlling the opening area of the intake and exhaust ports according to the temperature control program, the external gas having a temperature lower than the temperature in the furnace is taken into the circulation furnace. The temperature can be lowered slowly according to the desired temperature lowering rate, and it becomes possible to prevent troubles such as cracking and breakage caused by the expansion coefficient of the object to be heated.

Sectional view showing an embodiment of a circulation type electric furnace according to the present invention Schematic of a linear slider for adjusting the opening area of the intake and exhaust ports Schematic of a fan-shaped rotary plate for adjusting the opening area of the intake and exhaust ports Explanatory drawing which shows the example of a shape of the opening part in an inlet or an exhaust port Schematic of valve body for adjusting opening area of intake and exhaust ports Explanatory drawing which shows embodiment at the time of carrying out opening control of interlocking | linkage with an inlet port and an exhaust port simultaneously The perspective view which shows other embodiment of the circulation type electric furnace concerning this invention An explanatory view showing an embodiment of a circulation type electric furnace concerning the present invention Explanatory drawing which shows the attachment angle of a centrifugal fan Sectional view showing another embodiment of a circulation type electric furnace according to the present invention Sectional view showing another embodiment of a circulation type electric furnace according to the present invention

The present invention is an electric furnace in which gas circulates in a duct, including an intake port having one or more opening / closing means and an exhaust port having one or more opening / closing means, and a heater unit and ventilating in the middle of the circulation path. By setting the opening area of the intake and exhaust ports, it is possible to take in gas outside the electric furnace and to cool the object at a desired cooling rate. It features.
Hereinafter, embodiments of the circulation type electric furnace according to the present invention, that is, the configuration and operation thereof will be described based on the drawings.

  In addition, the circulation type electric furnace according to the present invention is not particularly limited to the embodiments described below, and a material, a shape, a configuration, and the like capable of exhibiting the same effect within the scope of the technical idea of the present invention. The operation and the like can be changed as appropriate.

FIG. 1 is a cross-sectional view showing an embodiment of a circulation type electric furnace according to the present invention.
The circulation type electric furnace according to the present invention comprises a duct 6 constituting a sealed pipe-like space, and the gas flows in the duct 6. In addition, since drawing is showing in figure by sectional drawing, although it is shown by the aspect comprised with the external heat insulation wall 1 and the internal heat insulation wall 2 as a structure of the duct 6, the duct 6 whole is a pipe shape with heat insulation wall. It is not necessary to explain again that it is the composition surrounded by.
The outer heat insulating wall 1 is provided with an open / close door 5 for inserting the object 4 to be heated, and the duct 6 is provided with a ventilation mounting portion 3 for placing the object 4 to be heated. As long as the air-permeable mounting portion 3 is capable of mounting the object to be heated 4 and has air-permeability capable of passing the circulating gas, the specific shape and structure thereof are particularly limited. For example, a net, a punching plate or the like may be employed. The breathable mounting portion 3 also functions as a fluid resistance means for the gas circulating in the duct 6. After the object to be heated 4 is placed on the air-permeable placement unit 3 via the open / close door 5, the open / close door 5 is closed, and a duct 6 which is a sealed pipe-like space is formed.

  The gas circulates in the duct 6 through the gap of the air-permeable mounting portion 3. In the duct 6, a blower 7 for circulating a gas is provided. The blower 7 includes, for example, a circulation motor 7a, a rotation shaft 7b, and a propeller fan 7c, and the propeller fan 7c attached to the rotation shaft 8 of the circulation motor 7 rotates to flow gas in the wind direction 10. make. The gas flow passes through a heater unit 11 provided in the duct 6 to heat the gas. The heater unit 11 has a heating element incorporated therein and generates heat by Joule heat when a voltage is applied.

  The heater unit 11 is connected to the controller 13 via the wire 12, and the control unit 13 supplies the heater unit 11 via the wire 12 while controlling the power input from the outside.

The gas that has passed through the heater unit 11 is heated and the temperature rises. The gas circulates in a direction such as the wind direction 17 and the wind direction 18 in the duct 6 which is a closed space.
It is preferable that the temperature sensor 15 be disposed in the middle of the circulation path in the duct 6 as shown, and the temperature sensor 15 placed detects the temperature of the heated gas and uses the detected temperature as an electric signal. Then, they are input to the control unit 13 via the conductor 16.
The gas whose temperature has risen heats the object to be heated 4, passes through the permeable mounting portion 3, and is reaccelerated by the propeller fan 7 c.

The wind speed of the gas in the duct 6 is uniquely determined mainly by the number of revolutions of the propeller fan 7c, the shape in the duct 6, the fluid resistance of the air-permeable placement portion 3, and the like.
The above operation is repeated, and the gas circulates in the duct 6.
The specific type of the blower 7 is not particularly limited. For example, the propeller fan 7 c shown can be replaced by a centrifugal fan 96 described later such as a sirocco fan, a turbo fan, a blower fan, etc. By changing the number of revolutions of the motor 7a for circulation accordingly, it is possible to change the volume of air that hits the object 4 to be heated.

The air intake port 19 is constituted of, for example, a slider 20 and a control rod 21 as shown in the figure, and at least one or more downstream of the air permeable mounting portion and upstream of the blower 7 are provided. When the control rod 21 is moved in the direction indicated by the moving direction 22, the opening area of the intake port 19 is enlarged.
The exhaust port 23 is constituted of, for example, a slider 24 and a control rod 25 as illustrated, and is provided at least one or more downstream of the blower 7 and upstream of the air-permeable mounting portion. When the control rod 25 is moved in the direction indicated by the moving direction 26, the opening area of the exhaust port 23 is enlarged.
Since the duct 6 is provided with the air-permeable mounting portion, opening the intake port 19 and the exhaust port 23 allows outside air to be taken into the duct 6.
During heating in the furnace, the intake port 19 and the exhaust port 23 are closed without opening and there is no introduction of gas from outside the furnace.

FIG. 2 is a schematic view of a linear slider for adjusting the opening area of the intake port 19 and the exhaust port 23, and is a drawing of an example in which the sliders 20 and 24 of the intake port 19 and the exhaust port 23 are embodied.
That is, the sliders 20 and 24 are moved in parallel by a rack and pinion gear system. The stepping motor 30 and the pinion gear 32 attached to the rotary shaft 31 are rotated in the rotational direction 33, and the rack gear 34 is combined with this to convert the rotational movement into the linear movement as the movement direction 35. it can.

  The sliders 20, 24 are sandwiched between the two slide guides 29a, 29b and move inside thereof. The sliders 20 and 24 are connected to the rack gear 34. The stepping motor 30 receives the rotational power signal from the control unit 13 and rotates.

The control unit 13 controls the entire system of the circulating electric furnace according to the present invention, and controls heating of the heater unit 11 and opening / closing control of the inlet 19 and the outlet 23 based on the temperature detected by the temperature sensor 15 ( Control the control rods 21 and 25 connected to the sliders 20 and 24).
The control unit 13 is connected to a lead 14 connected to a bus with a large capacity, and receives supply of power through the lead 14.

In controlling the intake port 19 and the exhaust port 23, the control unit 13 needs to know the initial value that the opening area is zero, and makes the aperture areas of the intake port 19 and the exhaust port 23 zero when the power is turned on. .
As a detection means with an opening area of zero, the control unit 13 rotates the stepping motor 30 in the direction in which the opening area becomes zero simultaneously with the power-on.
The rotational speed is a rotational speed sufficient for the opening to be zero, assuming that the opening area of the intake port 19 and the exhaust port 23 is maximum.
As a result, the sliders 20 and 24 abut against the stopper 36. With this as an origin, the distance from this point can be stored each time a signal is sent to the motor by the control unit 13, and the opening area can be grasped.

  At this time, when the intake port 19 and the exhaust port 23 do not have the maximum value, they hit the stopper 36 during the operation, but the rotational current continues to flow at this time as well. The stepping motor 30 is mechanically locked, but the stopper 36 and other mechanical parts are designed to have sufficient resistance to the force generated by the stepping motor 30, and the stepping motor 30 is The control unit 13 controls the rotation current so that burning of the coil inside the motor and other troubles do not occur even when the locked state continues. Alternatively, even if the current control is not performed, parts having sufficient resistance are used.

  Instead of the stopper 36, a mechanism for mechanically or optically detecting the position of the sliders 20 and 24 is provided at a position where the sliders 20 and 24 are closed, and the sliders 20 and 24 are closed by the detection signal. An aspect of detecting

The structure using the fan-shaped rotary plate 41 can also be considered about the structure of the inlet 19 and the exhaust port 23. FIG. FIG. 3 is a schematic view using a fan-shaped rotating plate for adjusting the opening area of the inlet 19 and the outlet 23.
The drive shaft 45 of the stepping motor 46 is disposed in the portion 44, and the fan-shaped rotary plate 41 attached to the shaft is rotated to change the opening areas of the intake port 19 and the exhaust port 23 forming a fan-shaped opening. It can be done.
The stopper 43 plays the same role as the stopper 36 in the linear slider system.

Here, the atmospheric pressure difference between the intake port 19 and the exhaust port 23 with respect to the atmospheric pressure will be described.
When the rotation stage of the circulation motor 7a in the fan 7 is stopped, the air pressure in the duct 6 is equal to the atmospheric pressure. By rotating the propeller fan 7c in this state, a flow of gas to the wind direction 10 is created.

  At this time, the downstream (exhaust side) of the propeller fan 7c becomes higher than the atmospheric pressure, and conversely, the upstream (intake side) of the propeller fan 7c becomes lower than the atmospheric pressure. As shown in FIG. 1, the propeller fan 7c, the heater unit 11, and the breathable mounting portion 3 are arranged, gas flows as arrows 10, 17 and 18, and the breathable mounting portion 3 is suitable for the flow of gas. Higher than atmospheric pressure from the downstream of the propeller fan 7c to the heater unit 11, the exhaust port 23 and the portion of the breathable mounting portion 3 with the breathable mounting portion 3 as the boundary. The pressure to the upstream of the sexing portion 3, the intake port 19, and the propeller fan 7c is lower than the atmospheric pressure.

  In this state, when the intake port 19 and the exhaust port 23 provided in the flow path of the circulating gas are opened respectively, the air pressure is lower than the ambient pressure at the intake port 19, so the gas is taken in. Since the air pressure is higher than the surrounding air pressure, the gas is discharged.

At this time, if the inside of the furnace has a high temperature, the exhaust port 23 exhausts the high temperature gas and the intake port 19 takes in the external gas. If the fluid resistances of the intake port 19 and the exhaust port 23 do not have a large difference as compared with the fluid resistance of the breathable mounting portion 3, the external gas is diverted and a part of the diverted gas is the heated object 4. Cooling.

  When the intake port 19 and the exhaust port 23 are greatly opened for rapid cooling, that is, when the fluid resistance of each opening is extremely low, the gas taken in from the outside is sucked from the intake port 19 and exhausted from the exhaust port 23 Since only the heater unit 11 is cooled, the object to be heated 4 can not be cooled sufficiently.

The amount of gas taken in at a temperature lower than the temperature in the furnace is approximately proportional to the opening area, and the opening area is generally determined by the result of the PID calculation.
Set value (SV) measured value (PV) deviation (e) When it is assumed that the manipulated variable (MV), the value obtained by subtracting the measured value (PV) from the set value (SV) is the deviation (e). When the value is positive, the manipulated variable (MV) is usually positive to heat the heater. The electric power is supplied to the heater according to the operation amount (MV) to heat the heater, and the gas flowing in the heater unit 11 is heated by the heater unit 11, thereby heating the circulating gas and further heating the gas. The object to be heated 4 is heated by being in contact with the object to be heated 4. Incidentally, even if the deviation (e) is positive, the manipulated variable (MV) which is the calculation result of the PID may be minus depending on the calculation result of the PID.
When the operation amount (MV) is negative, the opening area of the suction port 19 and the discharge port 23 is increased or decreased according to the operation amount (MV).

By moving the opening area of the intake port 19 and the exhaust port 23 until the displacement determined by the PID calculation result as described above, the amount of taking in the gas is determined.
Although the intake port 19 and the exhaust port 23 move in unison, they do not deviate from the spirit of the present invention even if they are not necessarily the same opening surface. However, when either one is closed, the effects of the present invention can not be exhibited.
In the case of changing the shape of the opening, there is an element based on the difference between the current temperature of the object 4 to be heated and the temperature of the gas taken in, and an element based on the air volume, and the cooling property is not necessarily proportional to the opening area. There is.

FIG. 4 is an explanatory view showing an example of the shape of the opening at the intake port 19 or the exhaust port 23; (a) is a net-like opening 51, (b) is a triangular opening 52, and (c) is a fan-shaped triangular opening Part 53 is shown.
The mesh opening 51 has a fluid resistance at the opening 19 or the opening 23 and is used for the purpose of making the performance of the sliders 20 and 24 insensitive, so that the resolution of the pulse motor can be apparently increased. It is possible.
The triangular openings 52 and the fan-shaped triangular openings 53 can start opening from the thin tip at the beginning of the opening, and therefore have the function of making the performance of the sliders 20 and 24 insensitive and perform minute temperature control. Can be done at this tip.

  FIG. 5 is a schematic view of the valve body 61 for adjusting the opening area of the intake port 19 and the exhaust port 23, (a) is a partial cross-sectional view showing the structure of the valve body 61, (b) and (c) These are explanatory drawings which show the difference in the position of the drive shaft 62 in the valve body 61. FIG. That is, as a structure for adjusting the opening area of the intake port 19 and the exhaust port 23, a method using the valve body 61 can be adopted.

In FIGS. 5A and 5B, a drive shaft 62 is provided substantially at the center of the valve 61, and the stepping motor 63 can change the angle of the valve 61 about the drive shaft 62.
When the valve body 61 becomes parallel to the gas flows 65a and 65b, the flow rate becomes maximum, and when it becomes perpendicular, the gas flow stops.
The valve box 64 is an outer frame that accommodates the valve body 61, and corresponds to the ducts 83 and 85 in FIG.

Further, as shown in FIG. 5C, an aspect in which the drive shaft 68 is provided close to one end of the valve body 61 is also possible.
When the drive shaft 62 is disposed substantially at the center of the valve body 61 as shown in FIG. 5B, the rotational torque generated on the drive shaft 62 by the flow of gas cancels around the drive shaft and does not occur. On the other hand, when the drive shaft 62 is moved to one end of the valve body 61 as shown in FIG. 5C, the gas flow 65c generates rotational torque in the drive shaft 62 by the flow velocity, but the stepping motor There is no problem if 63 has enough rotational torque to overcome it.

The valve body 61 has a sinusoidal shape with respect to the angle of the stepping motor 63 when the valve body 61 is located at a position perpendicular to the fluid, that is, when the flow of wind is zero.
The characteristic of a sine curve with a small amount of initial change is an effective means for minute control.

Although the two openings of the intake port 19 and the exhaust port 23 can be controlled separately, respectively, it is also possible to control the two ports simultaneously in conjunction with each other. FIG. 6 is an explanatory view showing an embodiment in which the intake port 19 and the exhaust port 23 are simultaneously controlled by using, for example, the connecting rod 71. As shown in FIG. The valve body 61 of the intake port 19 and the valve body 61 of the exhaust port 23 are interlocked by one stepping motor 63 and controlled to open at the same angle.

FIG. 8 is an explanatory view showing an embodiment of a circulation type electric furnace according to the present invention.
The air-permeable mounting portion 92 for mounting the object to be heated 4 shown in FIG. 8 is larger than the air-permeable mounting portion 3 shown in FIG. 1 and can heat many objects to be heated 4.
On the other hand, since the upstream duct 6 thinner than the area of the permeable mounting portion 92 blows hot air to the central portion, the central portion of the permeable mounting portion 92 is heated from the outside, and the temperature distribution is deteriorated.
In order to prevent this, it is preferable to dispose a baffle plate 91 upstream of the air-permeable mounting portion 92 in the duct 6 and to diffuse the hot air so as not to concentrate at the central portion.

By the way, as shown in FIG. 8, the aspect using the centrifugal fan 96 instead of the propeller fan 7c can also be adopted.
In FIG. 8, the circulation motor 93 can rotate the fins 98 of the centrifugal fan 96 in the rotational direction 95 via the rotation shaft 94 to generate a gas flow in the wind direction 97 using centrifugal force.
The suction port of the centrifugal fan 96 is disposed on both sides or one side of the rotation shaft.

FIG. 9 is an explanatory view showing the form of the centrifugal fan 96, where (a) shows the rotational axis of the centrifugal fan 96 at right angles to the flow of gas, and (b) shows the rotational axis of the centrifugal fan 96 It shows the case of being parallel to the flow.
The centrifugal fan 96 in FIG. 8 corresponds to the installation angle of FIG. 9 (a). In the centrifugal fan 96, the gas bends from the side at a right angle as in the wind direction 103 and flows into the central portion of the centrifugal fan 96. At this time, the thickness of the centrifugal fan 96 must be thinner than that of the duct 6 so as not to impede the flow of gas. The gas input to the centrifugal fan 96 is rotated and accelerated by the rotation of the fins 98, and is discharged in the direction of the wind direction 105a by centrifugal force.

  FIG.9 (b) is a figure at the time of rotating 90 degree | times and arrange | positioning Fig.9 (a). In the centrifugal fan 96, the gas flows in a wind direction 104 parallel to the rotation axis. The rotated and accelerated gas is discharged in the direction of the wind direction 105b by centrifugal force.

Next, another embodiment of the circulation type electric furnace according to the present invention will be described with reference to FIG. The same parts as those of the first embodiment will not be described.
FIG. 10 is a cross-sectional view showing another embodiment of the circulation type electric furnace according to the present invention, in which the intake port 19 and the exhaust port 23 are provided downstream of the blower 7 and upstream of the permeable mounting portion. Show.

At this time, with regard to the positional relationship between the intake port 19 and the exhaust port 23, the exhaust port 23 is disposed in the front stage (upstream side) and the intake port 19 is disposed in the rear stage (downstream side). If this arrangement is reversed, the outside air taken in from the air intake port 19 will be immediately expelled from the air exhaust port 23, which does not make the meaning of the furnace cooling.
In addition, the positional relationship between the intake port 19 and the exhaust port 23 may be separated from each other, but it may be adjacent to each other as illustrated. By taking such an aspect, for example, an opening is provided at one place in the outer heat insulating wall 1 of the duct 6, and two pipes for intake and exhaust are attached thereto, whereby the intake port 19 and the exhaust port 23 are disposed. It contributes to the ease of device design and assembly processing.

In the case where the intake port 19 and the exhaust port 23 are arranged adjacent to each other, as shown in the figure, the opening / closing means in the intake port 19 and the opening / closing means in the exhaust port 23 are integrated by one plate 110. The configured aspect can be taken.
The plate 110 includes a rotating shaft 111 at a substantially central portion thereof, and rotates around a boundary between the adjacent intake port 19 and exhaust port 23 as a fulcrum. At this time, the plate 110 located on the side of the intake port 19 rotates inward (toward the duct 6), and the plate 110 located on the side of the exhaust port 23 rotates outward.
According to this aspect, the opening and closing operations of the intake port 19 and the exhaust port 23 can be interlocked to be performed in one operation, which contributes to operability.

The amount of rotation of the plate 110 is appropriately determined in consideration of the amount of outside air taken in from the air inlet 19 and the amount of hot air in the duct 6 from the air outlet 23.
In this embodiment, the plate 110 is rotated by 90 degrees to interrupt the circulation path of the duct 6 by making the length from the rotation axis 111 of the plate 110 to the outer peripheral end substantially the same as the inner width of the duct 6 It is also possible to totally replace the gas in the duct 6 with the outside air, thereby achieving rapid furnace cooling.

Next, another embodiment of the circulation type electric furnace according to the present invention will be described with reference to FIG. Descriptions of parts similar to those in the first embodiment and the second embodiment are omitted.
FIG. 11 is a cross-sectional view showing another embodiment of the circulation type electric furnace according to the present invention, wherein the intake port 19 and the exhaust port 23 are provided downstream of the blower 7 and upstream of the air-permeable mounting portion, An embodiment is shown in which the opening / closing means at the port 19 is constituted by the first plate 113 and the opening / closing means at the exhaust port 23 is constituted by the second plate 114.

  Regarding the positional relationship between the intake port 19 and the exhaust port 23, the exhaust port 23 at the front stage (upstream side) and the intake port 19 at the rear stage (downstream side) in this order Although it is possible, as shown in the figure, it is also possible to adopt an aspect of being arranged adjacent to each other as in the second embodiment.

  The first plate 113 constituting the opening / closing means at the intake port 19 and the second plate 114 constituting the opening / closing means at the exhaust port 23 respectively have the rotary shaft 111 at the end, and the first plate The body 113 is pivoted about the upstream boundary between the duct 6 and the intake port 19 as shown in the figure, and the second plate 114 is, as shown, the duct 6 and the exhaust port 19 as well. It turns around the downstream boundary as a fulcrum. At this time, the first plate 113 and the second plate 114 both rotate inward (toward the duct 6).

The amount of rotation of the first plate 113 and the second plate 114 is appropriately determined in consideration of the amount of outside air taken in from the air inlet 19 and the amount of hot air in the duct 6 from the air outlet 23.
The length from the rotation axis 111 to the outer peripheral end of the first plate 113 and the second plate 114 is made substantially the same as the inner width of the duct 6, so that at least the first plate 113 or the second It is also possible to interrupt the circulation path of the duct 6 by rotating any one of the plate members 114 by 90.degree. So that the gas inside the duct 6 can be totally replaced with the outside air, and a rapid furnace can be obtained. It is also possible to achieve internal cooling.

Next, another embodiment of the circulation type electric furnace according to the present invention will be described with reference to FIG. Descriptions of parts similar to those in the first to third embodiments are omitted.
FIG. 7 is a cross-sectional view showing another embodiment of the circulation type electric furnace according to the present invention, and shows an aspect in which means for increasing or decreasing the pressure in the air inlet 19 or the air outlet 23 is provided.

Although the drawing shows the case where the exhaust port 23 is provided with means for changing the pressure such as pressure increase or pressure reduction, the invention is not limited to the exhaust port 23 but the intake port 19 may be provided with the means.
In combination with the opening area of the intake port 19 and the exhaust port 23, the pressure change such as pressure increase or decrease can be made to facilitate the adjustment of the gas intake outside the electric furnace, and the object to be heated can be made at a desired cooling rate. It becomes possible to cool 4 linearly.

  Normally, by installing a fan 81 at the outlet of the duct 83 of the exhaust port 23 used for exhausting so as to take in gas in the direction of the wind direction 82, the exhaust port 23 is introduced into the duct 6 contrary to normal exhaust. Try to send in gas.

In this case, when the exhaust port 23 is viewed from the circulation type electric furnace main body, it has an intake function, and the gas sent in is exhausted from the intake port 19 and is exhausted in the direction of the wind direction 84 via the duct 85. Ru.
As described above, it is possible to force the gas into the duct 6 and reverse air intake and exhaust.
At this time, the sliders 20 and 24 move to the position corresponding to the operation amount (MV) which is the result of the PID calculation by the control unit 13, and change each opening.

Further, it is also possible to control the cooling only by the rotation of the fan 81 by controlling the rotation of the fan 81 and keeping the opening area of the intake port 19 and the opening area of the exhaust port 23 constant. At this time, the sliders 20 and 24 are closed until the start of cooling, and are opened simultaneously with the start of cooling.

  The present invention is very useful because it can be used as a heating means for any object to be heated regardless of the heating target. Therefore, the industrial applicability of the "circulating electric furnace" according to the present invention is considered to be great.

DESCRIPTION OF SYMBOLS 1 outside heat insulation wall 2 inside heat insulation wall 3 air-permeable mounting part 4 to-be-heated 5 opening-closing door 6 duct 7 fan 7a circulation motor 7b rotating shaft 7c propeller fan 10 wind direction 11 heater unit 12 lead 13 control part 14 lead 15 temperature sensor 16 Conductors 17 Wind direction 18 Wind direction 19 Air intake 20 Slider 21 Control rod 22 Movement direction 23 Exhaust port 24 Slider 25 Control rod 26 Movement direction 29a Slide guide 29b Slide guide 30 Stepping motor 31 Rotation shaft 32 Pinion gear 33 Rotation direction 34 Rack gear 35 Movement Direction 36 Stopper 41 Fan-shaped rotary plate 43 Stopper 44 Requires drive shaft 46 Stepping motor 51 Reticulated opening 52 Triangular opening 53 Sectored opening 61 Valve body 62 Valve body drive shaft 63 Stepping motor 64 Valve box 65a Air Body flow 65b Gas flow 65c Gas flow 71 Connecting rod 81 Fan 82 Wind direction 83 Duct 84 Wind direction 85 Duct 91 Baffle plate 92 Permeable mounting portion 93 Circulation motor 94 Rotating shaft 95 Rotational direction 96 Centrifugal fan 97 Wind direction 98 Fin 103 wind direction 104 wind direction 105 a wind direction 105 b wind direction 110 plate 111 rotating shaft 113 first plate 114 second plate

Claims (7)

In an electric furnace where gas circulates in the duct,
An intake port having one or more opening and closing means, and an exhaust port having one or more opening and closing means, and a heater unit, a ventilation mounting portion, and a blower are disposed in the middle of the circulation path.
A circulating electric furnace characterized by taking in gas outside the electric furnace and cooling the object at a desired cooling rate by changing the opening area of the intake and exhaust ports.   The air intake port is provided downstream of the air-permeable mounting portion and upstream of the blower, and the exhaust port is provided downstream of the air blower and upstream of the air-permeable mounting portion. Circulation type electric furnace.   The circulation type according to claim 1, wherein the air inlet and the air outlet are provided downstream of the blower and upstream of the air-permeable mounting portion or downstream of the air-permeable mounting portion and upstream of the air blower. Electric furnace.   The circulating electric furnace according to claim 3, wherein the air inlet and the air outlet are provided adjacent to each other. The opening and closing means at the intake port and the opening and closing means at the exhaust port are integrally formed of a single plate;
5. The circulating electric furnace according to claim 4, wherein the plate body has a rotary shaft at a substantially central portion thereof, and rotates around a boundary between an adjacent inlet and outlet as a fulcrum. The opening and closing means at the intake port is constituted by a first plate, and the opening and closing means at the exhaust port is constituted by a second plate.
The first plate body has a rotation shaft at an end, and is pivoted about the upstream boundary between the duct and the intake port as a fulcrum,
The circulation type electric furnace according to claim 3 or 4, wherein the second plate body is provided with a rotation shaft at an end portion, and rotates around a downstream boundary between the duct and the exhaust port as a fulcrum. .   By providing means for increasing or decreasing the pressure at the intake or exhaust port, and changing the pressure for increasing or decreasing the pressure together with the opening area of the intake and exhaust ports, gas outside the electric furnace can be taken in and desired. The circulating electric furnace according to any one of claims 1 to 6, wherein the object to be heated is cooled at a cooling rate.