JPH0325285A - Cooling device for electric furnace - Google Patents

Abstract

PURPOSE:To permit the control of the setting of a temperature in a furnace easily by a method wherein a regulating valve, whose amount of opening is changeable in accordance with the temperature variation of a furnace center tube, is provided in either one of an air supplying duct or an air discharging duct, which are connected to the openings of a gap between the furnace center tube and a heater unit and are installed from the outside to the inside of a room wherein an electric furnace is installed. CONSTITUTION:Both of an air supplying duct 41 and an air discharging duct 42, which are installed from the inside to the outside of a room R wherein an electric furnace is installed, are connected to both of the openings of a gap 24' between a furnace center tube 23 and a heater unit 25 respectively. The air supplying duct 41 is provided with a blower 43 and a regulating valve 44 is provide. below the blower 43 while an atmospheric temperature sensor 46, connected to a control box 45 attached to the outside of the electric furnace, is installed between the regulating valve 44 and the blower 43. According to this method, a temperature in the furnace, which is provided with a desired given cooling gradient, may be maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a cooling device for an electric furnace used in manufacturing magnetic heads for video tape recorders.

(Prior Art) Conventionally, for example, when manufacturing a head for a video tape recorder, a pair of half-core blocks are welded together using a bonding glass rod.

Figures 4(A) and 4(B) show the magnetic head! ! ! FIG. 2 is a schematic perspective view showing glass welding of core halves 10 and 10'' during manufacturing.

In the figure, reference numeral 11 is a glass rod for welding, and after it is set in an adhesive spring 12 and a track width regulating rod 13 formed by butting core halves 10 and 10'', it is later described as work a. {Fig. 4 (A)) Next, the furnace core tube of the electric furnace is heated to melt the glass rod 11 in the workpiece a, and then the furnace The core tube is cooled and the workpiece a set inside the furnace core tube is taken out. (Fig. 4 (B)) Here, in order to cool the furnace core tube, the heater is turned off and the furnace core tube is allowed to cool naturally. However, high temperatures (e.g. 400°C to 8°C) may be used.
It takes a long time to cool down the furnace core tube heated to 00℃), and productivity is extremely low.
5 and 6 are schematic elliptical diagrams showing an example 20 of a conventional electric furnace and an example 30 of a pond, both of which are designed to perform forced cooling. In both figures, the same components are given the same reference numerals, and the conventional example will be described below using both figures.

In the conventional electric furnace 20 shown in FIG. 5, a cooling fan 22 is installed in a stand 2l on which a pump, a power supply device, etc. are installed. A furnace core tube 23 is installed above the stand 21, and a heater section 23 is placed around it through an insulator 24.
A 5 is being thrown. In this electric furnace 20, a cooling fan 22 blows air to cool the outside of a heater section 25 provided so as to surround the furnace core tube, and the furnace core tube is cooled through this heater section 25. There is.

In another conventional electric cage 30 shown in FIG. 6, a furnace core tube 23 is installed above the stand 21, and a heater section 25 is installed around it through a ventilation gap 24'. ,
A blower 26 that sucks air using this gap is installed in the gap 2.
It is indirectly installed in the opening 27 of the 4th side. In this electric furnace 30, the furnace core tube 23 is directly cooled by blowing indoor air into the gap 24'' between the heater section 25 and the furnace core tube 23 using a blower 26. (Problems to be Solved by the Invention) However, in the electric furnace 20 described above, since the heater section 25 is cooled from the outside measurement, the cooling efficiency of the furnace core tube is poor.
In addition, in the electric furnace 30, since the furnace core tube 23 is directly blown and cooled, the cooling efficiency is better than that in the electric furnace 20, but it does not reduce the amount of indoor air. Since the air is used as cooling air and then discharged back into the room, cooling can be achieved at the required cooling gradient in the initial stage of cooling, but the temperature inside the room gradually rises due to the exhaust air exceeding 100°C. The cooling efficiency decreased and it was not possible to control the cooling gradient to the required level. FIG. 7 is a graph showing the change over time in the furnace temperature during cooling when the electric furnace 30 was used.

In the figure, the horizontal axis shows time, the vertical axis shows the temperature inside the furnace core tube, the solid line is the actual temperature inside the furnace, and the dotted line is the set temperature. As shown in the figure, in the conventional electric furnace 30, in the summer, the outside air is high, so the temperature is always higher than the set temperature, and in the winter, the temperature is lower than the set temperature at the initial stage of cooling, and then the temperature inside the room is lower than the set temperature. In addition, since a heat insulating material such as glass wool (not shown) is provided around the heater section 25, dust from the glass wool may enter the exhaust air. The mixture polluted the indoor air and worsened the working environment. Therefore, it would be possible to make the indoor air conditioning system compatible with this, but this would require huge equipment costs and was disadvantageous in terms of cost. (Means for Solving the Problems) The present invention has been made in order to solve the above problems, and includes a heater section around a furnace core tube, and allows ventilation between the furnace core tube and the heater section. In an electric furnace cooling device that forms a gap and performs cooling by blowing air into the gap, an air supply duct and an exhaust air duct are connected to the opening of the gap from the room where the electric furnace is installed to the outdoors. An electric furnace cooling device characterized by having a variable opening adjustment valve in response to temperature changes in the furnace core tube on one duct side of the duct, or a heater section around the furnace core tube. In an electric furnace cooling device, a ventilation gap is formed around the heater part, and air is blown into this gap to perform cooling.
An air supply duct and an exhaust duct are connected to the opening of the gap from the room where the electric furnace is installed to the outside, and one of the ducts has a variable opening size in response to temperature changes in the furnace core tube. i1i! ! ! ! The purpose is to provide a cooling device for an electric furnace characterized by the provision of a valve. (Example) FIG. 1 is a schematic configuration diagram showing a cooling device 40 for an electric furnace according to the present invention. In this figure, structural elements that are the same as those in FIGS. 5 and 6 are given the same reference numerals, and their explanations will be omitted. In FIG. 1, the difference between the cooling device 40 for an electric furnace according to the present invention and that of the conventional example is that a room R where the electric furnace is installed
an air supply duct 41 installed from the outdoors to the indoors;
The exhaust duct 42 connects the furnace core tube 23 and the heater section 25, respectively.
It is connected to both of the openings of the gap 24. This air supply duct 41 is provided with a blower 43, and an adjustment valve 44 is provided below the blower 43. Furthermore, between this adjustment valve 44 and the blower 43,
An outside air temperature sensor 46 connected to a control box 45 installed outside the electric furnace is installed. When using this electric furnace cooling device 40, by rotating the blower 43 installed in the air supply duct 41,
Cooling air is supplied from outside to the gap 24 between the heater part 25 and the furnace core tube 23, and exchanges heat with the surrounding heat of the furnace core tube 23, thereby cooling the furnace core tube 23 and making it warmer due to the heat exchange. Air passes through the exhaust duct 42 and is exhausted outside.

At this time, the temperature of the air supplied to the air supply duct is detected by the outside air temperature sensor 46, and the opening amount of the regulating valve 44 is changed in accordance with the detected temperature. That is,
For example, when the outside air is high, such as in the summer, the outside air temperature sensor 46 detects a high temperature, and the control box 45 issues an instruction to increase the opening amount of the adjustment valve 44 in order to increase the cooling effect. be. FIG. 2 is a block diagram of the control box in the electric furnace cooling device 40 according to the present invention.As shown in FIG. 2, the control box 45 includes an amplifier 4,
51, an arithmetic circuit 452, a position control servo circuit 453, a valve control servo motor 454, a valve position voltage converter 455, and other circuits.

Control of this control box 45 is performed as follows. First, the outside air temperature inside the air duct 41 is detected by the outside air temperature sensor 46. This detection signal is converted into a valve position instruction signal (t) indicating the opening amount of the valve 44 by an amplifier 451.
pressure). Next, the valve position instruction signal and the valve position signal (voltage) obtained from the valve position voltage converter 455 are calculated by the calculation circuit 452 to obtain a position deviation signal. Next, in the position control servo circuit 453,
The valve control servo motor 454 is controlled in response to the position deviation signal to control the opening and closing of the adjustment valve 44. In addition, the valve control servo motor 4
The rotation angle signal from 54 is supplied to a valve position detection circuit 455. This makes it possible to maintain the furnace temperature with a desired constant cooling gradient.

FIG. 3 is a graph showing the change in furnace temperature over time when the electric furnace cooling device 40 of the present invention is used. As is clear from the figure, it is possible to make the set temperature and the actual furnace temperature almost the same. In addition, in this embodiment, the gap 24 between the heater section 25 and the rod core tube 23 is
Although the explanation has been given using an example in which air passes through this gap (see Fig. 6), the example is not limited to this. Of course, it may also be a gap formed in the gap (see Figure 5). In addition, as a method of adjusting the cooling air, it is possible to adjust the amount of air by adjusting the rotation speed of the blower 43 of the air supply duct 41, but since the furnace core tube 23 and the blower 43 are very far apart, , it is difficult to precisely control the amount of 4 servings. Therefore, by providing the adjustment valve 44 near the furnace core tube 23 and controlling the air volume using the adjustment valve 44 as in the present invention, the actual temperature inside the furnace can be brought closer to the set temperature.

Furthermore, according to the present invention, all the cooling air uses outdoor air, so it is not affected by the indoor temperature.
In addition, since all the used cooling air is exhausted outside, foreign matter such as glass wool surrounding the furnace core tube 23 is not discharged into the room, maintaining an extremely clean condition. {Effects of the Invention} As described above, according to the electric furnace cooling device of the present invention, the working environment is not deteriorated at all.
A cooling device for an electric furnace that has a heater section around a furnace core tube, forms a ventilation gap between the furnace core tube and the heater section, and cools the electric furnace by blowing air into the gap. An adjustment valve whose opening amount can be varied in response to temperature changes in the furnace core tube is provided on one duct side of an air supply duct and an exhaust duct connected to the opening of the gap from the installed room to the outside. Alternatively, in the cooling device for an electric furnace, which has a heater part around a furnace core tube and forms a ventilation gap around the heater part, and air is blown into the gap to perform cooling. The supply air duct and the exhaust duct are connected to the opening of the gap from the room where the furnace is installed to the outside, and one of the ducts is equipped with an adjustment valve whose opening amount can be adjusted in response to temperature changes in the furnace core tube. Since it is characterized by having
Since it can take in outside air and release it to the outside air, there is no need to worry about contaminating the working environment where the device is installed, and the amount of cooling air can be changed by adjusting the opening amount of the valve according to the outside air temperature. This makes it possible to easily control the furnace temperature setting and provide an electric furnace cooling system with a constant cooling gradient.
There will be no cracks in the glass.

[Brief explanation of drawings]

No. FIG. 1 is a schematic configuration diagram showing a cooling device for an electric furnace according to the present invention, FIG. 2 is a servo block diagram of the cooling device for an electric furnace according to the present invention, and FIG. 3 is a diagram showing a cooling device for an electric furnace according to the present invention. Graphs illustrating changes in furnace temperature over time when using the cooling device shown in FIGS.
Fig. 6 is a schematic configuration diagram showing a conventional electric furnace, and Fig. 7 is a graph showing changes in furnace temperature over time during cooling when using a conventional electric furnace. 40...Electric furnace cooling device, R...Room, 41...
・Air supply duct, 42...Exhaust duct, 23...Furnace core tube, 24...Gap, 25...Heater part, 43...
・Blower, 44...Adjustment valve, 45...Control box, 451...Amplifier, 452;...Arithmetic circuit, 453...Position control servo circuit, 454...Valve control servo motor, 455
...Valve position voltage converter, 46...Outside temperature sensor Figure 1 Tato S

Claims (2)

[Claims] (1) A cooling device for an electric furnace that has a heater part around a furnace core tube, forms a ventilation gap between the furnace core tube and the heater part, and performs cooling by blowing air into this gap, An air supply duct and an exhaust duct are connected to the opening of the gap from the room where the electric furnace is installed to the outside, and one of the ducts has a variable opening size in response to temperature changes in the furnace core tube. A cooling device for an electric furnace characterized by being equipped with a regulating valve. (2) In an electric furnace cooling device that has a heater part around a furnace core tube, forms a ventilation gap around the heater part, and performs cooling by blowing air into this gap, the electric furnace is installed. An adjustment valve whose opening amount can be varied in response to temperature changes in the furnace core tube is provided on one duct side of an air supply duct and an exhaust duct that are connected to the opening of the gap from the room to the outdoors. A cooling device for an electric furnace characterized by the following.