JP2004069183A - Temperature control method for heating furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To heat and maintain the whole space inside of a furnace chamber including members such as furnace floor plates provided in the furnace chamber at the predetermined temperature when heating a material to be heated to the predetermined temperature with a heater through the atmosphere in the furnace chamber of a heating furnace. <P>SOLUTION: A specified heater is operated/controlled on the basis of the temperature of a space inside of the furnace chamber, and a heater near the furnace floor plates is operated/controlled on the basis of the temperature of the furnace floor plates. Namely, a temperature sensor is provided in the furnace floor plates, which are brought in contact with a conveyor belt circulating inside of the furnace chamber to transfer the material to be heated, or near there separately from a temperature sensor for controlling a heating means so that atmospheric temperature inside of the furnace chamber reaches a preset desirable temperature. The heating means near the furnace floor plates is controlled by the later temperature sensor so that the furnace floor plates are heated to the preset desirable temperature or near. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a method for controlling the temperature of a heating furnace, particularly a method for controlling the temperature of the heating furnace with high working efficiency, with a view to quickly transferring heat to an object to be heated.
[0002]
[Prior art]
In a continuous heating furnace, a heat-resistant conveyor belt that conveys the material to be heated is circulated in the furnace, and the material to be heated is sent into the furnace from the entrance of a tunnel-shaped furnace chamber maintained at a high temperature, and is heated and heated. Then, the object to be heated is subjected to a desired heat treatment by continuously passing through a cooling heat treatment step.
[0003]
The object to be heated conveyed into the furnace from the entrance and the conveyor belt on which it is placed are initially at room temperature or a low temperature close thereto, and are heated while being transferred into the high temperature furnace chamber. At this time, the hearth plate in the furnace chamber supporting the conveyor belt should be maintained at the same temperature as the temperature in the furnace chamber, but actually, the conveyor belt running thereon (indirectly the conveyor belt). The inventor of the present application has found that heat is deprived by contact heat transfer generated between the furnace chamber and the heating object, and the temperature is considerably lower than a desired set temperature in the furnace chamber.
[0004]
Heated objects including the conveyor belt receive heat energy in the furnace chamber, of course, mainly due to convection and radiation of the heated atmosphere in the furnace chamber, but contact heat transfer from the hearth plate with which the belt contacts cannot be overlooked. About as large.
[0005]
[Problems to be solved by the invention]
In a heating furnace, generally, a temperature sensor for controlling the temperature in the furnace chamber is mounted at a position where the transfer of the object to be heated in the furnace chamber is not obstructed, and at a position representative of the temperature in the furnace chamber. Thus, the operation of the heating elements provided in the upper, lower, or four corners of the furnace chamber is controlled.
[0006]
Due to the arrangement and operation of such a temperature sensor and a heating element, it has been considered that the furnace chamber is under a uniform temperature over the entire space. However, as described above, it is not the space where the temperature sensor is placed, but the low-temperature heated object, the conveyor belt on which it is mounted, and the belt And the space adjacent to them.
[0007]
However, when the temperature sensor detects the desired set temperature in the furnace chamber, the operation of the heating element is stopped regardless of the actual temperature of the hearth plate at that time, so that the temperature of the hearth plate is significantly higher than the desired set temperature. It is left at a low temperature.
[0008]
[Means to solve the problem]
Therefore, in order to compensate for such a temperature drop of the hearth plate, the present invention separately provides a temperature sensor in a space position near the hearth plate itself or a hearth plate that can represent the temperature of the hearth plate, and the temperature sensor is provided closest to the hearth plate. Controls the heating element installed in the furnace chamber. Of course, the maximum temperature of the hearth plate controlled in this way is limited to the same as or near the desired set temperature in the furnace chamber.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment An embodiment of the present invention will be described with reference to FIG. 1 which shows a part of a furnace chamber of a heating furnace suitable for carrying out the method of the present invention in an explanatory sectional view.
[0010]
An upper heating element 4 is provided in a space above the furnace chamber 2 which is formed by being surrounded by a furnace shell 1 made of a heat insulating material and has a rectangular section extending in a tunnel shape in the longitudinal direction of the heating furnace. It is mounted transversely to the longitudinal direction. Similarly, a lower heating element 5 is mounted in the lower space. Near the lower heating element, a 25 mm thick hearth plate 3 made of graphite refractory extends in the longitudinal direction of the furnace. A conveyor belt 6 is circulated and driven in the longitudinal direction of the furnace so as to slidably contact the hearth plate on the hearth plate. The heated portion 7 is continuously stacked on the belt.
[0011]
A temperature sensor 8 having a temperature detection terminal 9 placed in the above-mentioned upper space in the furnace chamber is provided. The temperature in the upper space detected by this sensor and considered to be representative of the temperature in the furnace chamber 2 is sent to a temperature control mechanism 13 via a temperature sensor circuit 12, and a heating element operating signal from the temperature control mechanism is sent from the temperature control mechanism 13. Is sent to the upper heating element 4 via the circuit 14.
[0012]
On the other hand, an 8 mm temperature detection terminal 11 of another temperature sensor 10 is attached to the hearth plate 3, and the temperature of the hearth plate detected by this is sent to another temperature control mechanism 16 via another temperature sensor circuit 15. Then, an operation signal for the lower heating element 5 is sent to the lower heating element 5 via another heating element signal circuit 17.
[0013]
Now, the temperature control mechanism 13 and another temperature control mechanism 16 were set at 800 ° C. and heated. The conveyor belt 6 having a width of 40 cm and a weight of 8 kg / m was driven at a speed of 20 cm / min. A large number of copper objects 7 having a total weight of 40 kg / m were successively placed on the belt and heated. When this series of objects to be heated 7 was interrupted by passing through the furnace chamber 2, the temperature of the hearth plate 3 was 798 ° C. as measured by a radiation temperature sensor having a radiation range of 18 mm in diameter.
[0014]
In comparison, the operation of the upper heating element 4 and the lower heating element 5 is the same as shown in FIG. Was controlled by the temperature control mechanism 23 of FIG. In FIG. 2, the same members as those in FIG. 1 are denoted by the same reference numerals as those in FIG. Reference numerals 14 ′ and 14 ″ in FIG. 2 are branch circuits of the circuit 14.
The temperature of the hearth plate 3 was measured to be 785 ° C. after the temperature control mechanism 23 was set to 800 ° C. and a series of objects to be heated 7 were heat-treated in the same manner as in the example.
[0015]
【The invention's effect】
In the above-described embodiment according to the method of the present invention, the temperature of the hearth plate 3 deprived by the contact heat transfer with the conveyor belt 6 to the belt and the object 7 to be heated mounted thereon is well compensated. Is evident. In other words, according to the method of the present invention, the entire space including each member in the furnace chamber is maintained at a desired preset temperature or at a temperature very close to the desired preset temperature, and the object to be heated is always kept at a predetermined temperature. There is an excellent effect that can be heated.
[Brief description of the drawings]
FIG. 1 is an explanatory sectional view showing a part of a furnace chamber of a heating furnace suitable for carrying out a method of the present invention.
FIG. 2 is an explanatory sectional view similar to FIG. 1, showing a part of a furnace chamber of a heating furnace whose temperature is adjusted by a conventional method.
[Explanation of symbols]
1—heat insulating furnace shell 2—furnace chamber 3 having a rectangular cross section—furnace floor plate 4—upper heating element 5—lower heating element 6—conveyor belt 7—object to be heated 8—of upper space in the furnace chamber Temperature sensor 9-temperature detection terminal 10 of temperature sensor 9-temperature sensor 11 of the hearth plate-temperature detection terminal 12 embedded in the hearth plate of temperature sensor 10-temperature sensor circuit 13-temperature control mechanism 14-upper heating element operation Signal circuit 14'-branch circuit 14 "of signal circuit 14-another branch circuit 15 of signal circuit 14-another temperature sensor circuit 16-another temperature control mechanism 17-signal circuit for operating the lower heating element

Claims (1)

Separately from the temperature sensor that controls the heating means so that the temperature of the atmosphere in the furnace chamber is set to a desired temperature set in advance, on the hearth plate itself in contact with a conveyor belt that circulates in the furnace chamber and transfers the object to be heated or A temperature sensor is provided in the vicinity thereof, and the heating means close to the hearth plate is controlled by the other temperature sensor to heat the hearth plate to the above-mentioned predetermined desired temperature or a temperature in the vicinity thereof. How to control the temperature of the heating furnace.

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