JPH047516Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to an improvement of a temperature control device for a heating furnace using a plurality of heaters.

Prior Art In a temperature control device for a heating furnace that heats using a plurality of heaters, a temperature control device is usually provided for each heater or a group of heaters, and the temperature of the area in the heating furnace corresponding to each heater or group of heaters is adjusted. By outputting a control signal from the temperature adjustment device to make the temperature coincide with each set temperature, electric power corresponding to the control signal is supplied to each of the heaters or a group of heaters.

Problems to be solved by the invention However, with this type of temperature control device,
Since a temperature control device is required for each region in the heating furnace, the device is complicated and expensive. In particular, in the case of a heating furnace that uses far-infrared heaters that output far-infrared rays, an extremely large number of far-infrared heaters are used, and in a heating furnace that uses far-infrared rays, it is possible to target with relatively high precision. Since it is required to maintain the temperature distribution in the furnace, the above-mentioned disadvantage becomes even more remarkable.

Means for Solving the Problems The present invention was made against the background of the above circumstances, and its gist is a temperature control device for a heating furnace that heats using a plurality of heaters. a) a temperature detection device that detects the actual temperature in the heating furnace; and (b) a common device that outputs a control signal so that a predetermined target temperature matches the actual temperature in the heating furnace. a temperature control device; and (c) manual setting means provided for each of the plurality of heaters, the manual setting means supplying electric power of a magnitude corresponding to the control signal to the heaters; a heater drive circuit that changes the power supply ratio with respect to the control signal according to the set value of the heater drive circuit;
It is to include.

Action and Effect of the Invention By doing this, a common temperature control device can
A control signal for matching the target temperature with the actual furnace temperature is determined, and the heater drive circuit determines the ratio of power supply to each heater with respect to the control signal set by the manual setting means, in other words. Electric power is supplied to each heater according to the output ratio between each heater. Therefore, it is easily configured using a common temperature control device, and the relative output ratio between each heater is set by each of the above-mentioned manual setting means, so that a desired heating/cooling temperature gradient ( In the case of a tunnel-type continuous heating furnace), the desired temperature distribution in the furnace can be obtained.

Embodiment In FIG. 1, inside the tunnel type continuous heating furnace 10, there is a conveyor belt 12 for conveying the object to be heated.
A rod-shaped far-infrared heater 14 is provided to heat the object on the conveyor belt 12.
A large number of reflectors 16 are disposed above and below the conveyed object. A thermocouple 18 is attached to the tunnel continuous heating furnace 10 for measuring the temperature at a specific position within the tunnel continuous heating furnace 10.

FIG. 2 is a circuit configuration diagram of a temperature control device for controlling the temperature of the tunnel type continuous heating furnace 10. The heater drive circuit 24 (24a...24j... ).
This control signal SC is a current signal, ie, an analog signal, which varies in the range of 4 to 20 mA, for example.
For example, ten far-infrared heaters 14 (14a...14j...) are installed above and below the conveyor belt 12.
is installed, the heater drive circuit 24
There are 20 sets of each of the far infrared heaters 14a to 14j arranged above, but in FIG. Only the heater drive circuits 24a to 24j provided are shown.

Note that if the temperature detection position is multiple and the furnace temperature can be detected by multiple thermocouples, the temperature can be further increased by using an arithmetic composite value such as an arithmetic mean value of the detected temperatures as an input signal to the temperature control device 20. Accurate temperature control is possible.

The heater drive circuits 24a to 24j each include a control element, such as an SCR, which supplies electric power of a magnitude corresponding to the control signal SC to the far-infrared heaters 14a to 14j, and an ignition control circuit that controls the timing of ignition thereof. The variable resistors 26a to 26j constitute a part of the ignition control circuit. These variable resistors 26a to 26j
The set values can be changed manually, and the power to the far-infrared heater 14 in response to the control signal SC can be changed by shifting the timing of ignition in the ignition control circuit according to the set value. Change the supply ratio. That is, variable resistor 2
6a to 26j set what ratio (%) of power to be supplied to the far infrared heaters 14a to 14j when the control signal SC is at its maximum value with respect to the maximum output capacity of the far infrared heaters 14a to 14j. In this embodiment, it functions as a manual setting means.

Each of the variable resistors 26a to 26j is set so as to obtain a desired furnace temperature distribution or heating/cooling temperature gradient (heat curve) in the tunnel type continuous heating furnace 10. For example, when obtaining the heat curve shown in FIG. 3, the variable resistor 26a is
25%, and variable resistors 26b to 26e are 50%
The variable resistors 26f to 26i are set to about 100%, and the variable resistor 26j is set to about 50%. Note that the x marks in FIG. 3 indicate temperature detection points.

In the temperature control device configured as described above, each heater drive circuit 24 operates according to the ratio according to the setting value of the variable resistor 26 based on the control signal SC output from the common temperature control device 20. Since power is supplied to the far-infrared heaters 14, the desired target temperature set in the setting device 22 can be obtained, and if the environmental conditions outside the furnace are constant and the object to be heated is constant, the temperature between each far-infrared heater 14 is A target constant heat curve corresponding to the thermal output ratio is obtained. Further, by manually adjusting the variable resistor 26, various heat curves corresponding to the set value can be obtained. Moreover, since only the common temperature control device 20 is used, the entire control device is configured extremely simply.

Next, another embodiment of the present invention will be described. In addition,
In the following description, parts common to those in the above-mentioned embodiments are given the same reference numerals, and the description thereof will be omitted.

In FIG. 4, a batch type heating device 30 has a large number of flat far-infrared heaters 32 arranged on one side, and a desired temperature distribution according to the heat output ratio of each far-infrared heater 32 is achieved. Then, for example,
The plastic sheet 34 is preheated prior to vacuum forming. As a result, the intensely heated region 36 of the plastic sheet 34 where plastic deformation is expected is locally heated to a sufficiently high temperature to enable plastic deformation, as shown in FIG.

The heating device 30 is provided with a temperature control device shown in FIG. In the figure, each variable resistor 26 is set so that the thermal output of the far infrared heater 32 facing the intense heating area 36 of the plastic sheet 34 is greater than that of the other. By molding the heated plastic sheet 34 on a mold, the region 36 of the plastic sheet 34 is easily plastically deformed and vacuum-formed into the shape shown in FIG.

Also in this embodiment, the common temperature control device 20
Based on the control signal SC output from the controller, each heater drive circuit 24 supplies power to the far-infrared heater 32 at a rate corresponding to the setting value of the variable resistor 26. When the desired target temperature is obtained and the object to be heated is constant under constant outside-furnace environmental conditions, each infrared heater 32
A desired heating distribution can be obtained according to the thermal output ratio between the two, and the device can be easily configured using a common temperature control device 20.

Although one embodiment of the present invention has been described above based on the drawings, the present invention can also be applied to other aspects.

For example, in the embodiments described above, far infrared heaters 14 and 32 were used, but other types of heaters may be used.

Further, in the above embodiment, the thermocouple 18 for detecting the ambient temperature inside the tunnel type continuous heating furnace 10 or the batch type heating device 30 is used as a temperature detection device, but the surface of the far infrared heater 14 or 32 is A thermocouple or a radiation thermometer that detects temperature may be used as the temperature detection device.

Further, in the above-described embodiment, the temperature adjustment device 20,
Although the heater drive circuit 24 is constituted by an analog type circuit, it may be constituted by a digital type circuit.

Furthermore, the control signal SC may be an on/off signal.

In addition, a plurality of thermocouples that detect temperatures at a plurality of positions are provided, and a calculation device that calculates and synthesizes the temperatures of the plurality of points detected by the thermocouples according to a predetermined calculation formula is provided, and the calculation result is One type of temperature may be used as the actual temperature.

The above-mentioned embodiment is merely an embodiment of the present invention, and various modifications may be made to the present invention without departing from the spirit thereof.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating a heating furnace to which the temperature control device of FIG. 2 is applied. FIG. 2 is a diagram illustrating the configuration of a temperature control device according to an embodiment of the present invention.
FIG. 3 is a diagram illustrating the setting method of the variable resistor in the embodiment of FIG. 2. FIGS. 4 and 6 are views corresponding to FIGS. 1 and 2 in other embodiments of the present invention. FIG. 5 is a diagram illustrating the strongly heated region of the material to be heated in the embodiment of FIG. 4. FIG. 7 is a diagram illustrating the shape of the material to be heated in FIG. 5 after molding. 10...Tunnel type continuous heating furnace (heating furnace), 1
4, 32... far infrared heater (heater), 18...
... thermocouple (temperature detection device), 20 ... temperature adjustment device, 24 ... heater drive circuit, 26 ... variable resistor (manual setting means), 30 ... heating device (heating furnace), SC ... control signal .

Claims (1)

[Claims for Utility Model Registration] A temperature control device for a heating furnace heated using a plurality of heaters, comprising: a temperature detection device for detecting the actual temperature in the heating furnace; a predetermined target temperature; It has a common temperature control device that outputs a control signal so that the actual temperature in the heating furnace matches, and manual setting means provided respectively corresponding to each of the plurality of heaters, Temperature control characterized by comprising: a heater drive circuit that supplies a corresponding amount of electric power to the heater and changes the supply ratio of the electric power to the control signal according to the setting value of the manual setting means. Device.