KR930001126B1 - Automatically flow controlled continuous heat treating furnace - Google Patents

Abstract

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Description

Continuous heat treatment with automatic flow control

1 is a top plan view of a heat exchange type continuous heat treatment furnace having an automatic flow control system according to a first embodiment of the present invention.

2 is a vertical cross-sectional schematic of FIG.

3 is a schematic diagram of an automatic flow control system used in the continuous heat treatment furnace of FIG.

4 is a graph showing the relationship between the temperature of the workpiece and the temperature of the atmospheric gas to be treated in each compartment or heat treatment zone formed in the continuous heat treatment furnace of FIG.

5 is a schematic view similar to FIG. 3 as in accordance with a second embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

T: Heat Exchanger Continuous Heat Treatment Furnace A: Preheater

B: High temperature treatment table C: Cooling table

M: Electric Motor EY: Comparator

3: bulkhead 5a, 6a: first compartment

5b, 6b: Second division room 6c: Third division room

7: convection fan 8: first duct

9: second duct 10: hood

11 injection nozzle hole 12a

12b: discharge door 14a: first damper

14b: second damper

TECHNICAL FIELD The present invention relates to a continuous heat treatment furnace, and more particularly, to a heat exchange type continuous heat treatment control system having an automatic flow control system that allows energy savings to be performed perfectly.

In general, various attempts have been proposed to improve energy saving in a continuous heat treatment furnace consisting of a pre-heating zone, a high temperature treatment zone, and a cooling zone.

Japanese Patent Publication No. 45-10610 is arranged substantially in a “U” shape, and the preheating and cooling stages are arranged in parallel to each other, and the partition walls separated from the ceiling walls are subjected to these two heat treatments. One is disclosed by the continuous heat treatment provided between the stages. This arrangement allows heat exchange between the preheating zone and the cooling zone.

However, this type of continuous heat treatment allows efficient heat exchange as the temperature difference between the atmospheric gas and the workpiece to be treated cannot be increased because, for example, atmospheric gases are mixed therein in a preheating or cooling zone. The disadvantage is that you can't.

U.S. Patent No. 4,449,923 (corresponding to Japanese Patent Application No. 56-13126) and Japanese Patent Application No. 56-182515 are both proposed by the same applicant of the present invention. It was developed.

The former U.S. patent unifies the preheating and cooling stages into one, and the charge end portion of the preheating stage and the discharge end of the cooling stage are communicated with each other by a circulation duct installed outside the furnace. The high temperature atmospheric gas is allowed to pass through the preheating zone to preheat the workpiece to be treated, while circulating the atmospheric gas whose temperature is reduced by heat exchange with the workpiece to the high temperature treatment zone.

In this kind of furnace, the temperature difference between the atmospheric gas and the work piece is relatively small since the temperature of the atmospheric gas is substantially adjusted while notifying the preheating zone and the cooling zone. As a result, it is difficult not only to control the temperature of the workpiece by preheating or cooling to a predetermined temperature, but also to maintain a predetermined cooling rate for the workpiece.

In the latter Japanese patent application, both the preheating stage and the cooling stage are divided into a plurality of compartments each having a convection fan installed on its ceiling, and the final compartment of the preheating stage is connected to the cooling stage through a duct. In communication with the first compartment, it is configured to guide the atmospheric gas of the cooling zone into the last compartment of the preheating zone and further to the first compartment.

Note that the flow rate of the atmospheric gas flowing from the preheating zone to the cooling zone or from the cooling zone toward the preheating zone is inversely proportional to the absolute temperature of the atmospheric gas in the heat treatment zone to which the atmospheric gas is supplied. That is, when atmospheric gas is supplied from the preheating zone to the cooling zone, the absolute temperature of the atmospheric gas in the cooling zone is inversely proportional. In particular, since the temperature of the atmospheric gas of the preheating zone varies greatly depending on the presence of the workpiece to be treated, the flow rate of the atmospheric gas supplied from the preheating zone toward the cooling stage also varies greatly.

The term "flow rate" refers to the volume of gas that flows within unit time at a standard condition of 0 ° C and 1 atmosphere.

Since the flow rate of the atmospheric gas supplied through the duct in any one of the above structures is changed, the atmospheric gas from the preheating zone or the cooling zone is introduced into the treatment passage. Therefore, the atmospheric gas introduced into the treatment tray is heated unnecessarily and economically in the treatment table.

Accordingly, the present invention was developed to substantially eliminate the above disadvantages inherent in the conventional continuous heat treatment furnace, and an essential object of the present invention is an improved continuous heat treatment having an automatic flow control system capable of completely saving energy. In providing the furnace. To this end, according to the present invention, a new continuous heat treatment furnace is provided with an automatic flow control system. The continuous heat treatment furnace has a high temperature treatment table having a heating means therein, a preheating table and a high temperature table disposed at one end of the high temperature treatment table. It has a cooling stand attached to the other end of the treatment station, and the preheating stand and the cooling stand provide an improved continuous heat treatment furnace equipped with an automatic flow control system, each of which is partitioned into a number of compartments with convection fans on their own ceilings. do. The automatic flow control system includes a first duct means for communicating the preheating zone, the last compartment and the first compartment of the cooling compartment, a second duct means for communicating the last compartment of the cooling compartment and the first compartment of the preheater, and in the middle of the first duct means. A first flow control means for adjusting the flow rate of the atmospheric gas flowing in the first duct means and second flow control means for adjusting the flow rate of the atmospheric gas disposed in the middle of the second duct means and adjusting the flow rate of the atmospheric gas flowing in the second duct means; have. By this arrangement, the flow rate of the atmospheric gas introduced into the preheating stage and the flow rate of the atmospheric gas introduced into the cooling stage are automatically adjusted to coincide.

In this arrangement, instead of the second duct means, one end is connected to the last compartment of the cooling stand and the other end is replaced by another duct means, which is connected to the fan or blower, so that the ambient air is fed into the cooling stand by the fan and heat treated in the furnace. The workpiece may be cooled.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Referring to the drawings, FIGS. 1, 2 and 3 show a heat exchange type continuous heat treatment furnace T according to a first embodiment of the present invention. This heat treatment furnace (T) is composed of a preheating table (A), a high temperature processing table (B), and a cooling table (C), and these three heat treatment tables (A, B, and C) are provided on two separating walls (2). Separated from each other. The preheating zone A is further divided into two compartments of the first compartment 5a and the first compartment 5b by a partition wall 3, and the cooling zone C is similarly divided into two partition walls ( 4) divided into three compartments, namely the first compartment 6a, the second compartment 6b and the third compartment 6c, and these compartments 5a, 5b, 6a, 6b. And 6c are each provided with circulation or convection fans 7. The high temperature treatment table B is a high temperature treatment table provided with a plurality of direct type burners 1 and a plurality of circulation or convection fans 7. A series of conveying rollers 13 are rotatably installed in the furnace to convey the processing workpiece W in the direction of the arrow D. FIG. The furnace is also provided with a charging door 12a for charging the work piece W therein and a discharge door 12b for discharging the work piece W from the furnace after the heat treatment.

The second compartment 5b, which is the last compartment of the preheating zone A, communicates with the first compartment 6a of the cooling zone C via the first duct 8, and similarly to the first compartment of the preheating zone A. 5a communicates with the third compartment 6c, which is the last compartment of the cooling table C, through the second duct 9, and the two gas flow control dampers 14a and 14b are connected to the first duct (1). 8) and 2nd duct 9, respectively. Atmospheric gas is the first compartment 6a, the first duct 8 of the cooling table C, the second compartment 5b of the preheater A, the first compartment 5aq of the preheater A, and the first compartment. 2 ducts, circulated in the direction of the arrow E in the order of the third compartment 6c and the second compartment 6b of the cooling table C, and then again the first compartment of the cooling table C ( You will be returned to 6a).

In the continuous heat treatment furnace of this structure, the flow rate of the atmospheric gas is automatically by the first damper 14a and the second damper 14b connected to each electric motor M, as shown in FIG. Adjusted.

In particular, three thermo-sensors (TE1), (TE2) and (TE3), such as thermocouples, etc., are placed in each compartment 6a, 6b and 6c of the cooling table C. ) And detect the temperature of the atmospheric gas in these compartments 6a, 6b and 6c. These thermograms (TE1), (TE2) and (TE3) are electrically connected to the respective temperature display controllers (TIC1), (TIC2) and (TIC3) to send electrical signals to these controllers. The display controllers TIC1, TIC2 and TIC3 are electrically connected to one comparator EY so as to output respective voltage signals to the comparator. A second of the three signals output from these temperature display controllers TIC1, TIC2, and TIC3 being operably connected to the second damper 14b by comparing with the reference voltage in the comparator EY By controlling the electric motor M, the opening degree of the second damper 14b disposed in the middle of the second duct 9 is adjusted.

Furthermore, each of the first duct 8 and the second duct 9 separately configures the thermo sensor TE11 and TE12 to detect the temperature of the atmospheric gas flowing therein, and the differential pressure transducer The transmitters (DPT110 and (DPT12) are configured to detect the flow rate of the atmospheric gas, but of course these thermometer sensors (TE11) and (TE12) and the differential pressure transducers (DPT11) and (DPT12) are connected to one flow arithmetic. An electrical connection is made to the controller FC to output a voltage signal, which is the product of the two outputs from the thermo sensor TE11 and the differential pressure transducer DPT11. Can be driven according to the result obtained by comparing the opening degree of the first damper 14a with the flow calculation controller FC by comparing the product of the two thermostat sensors TE12 and the differential pressure transducer DPT12 multiplied by To control the first electric motor (M) The.

In this embodiment, the first compartment 5a and the second compartment 5b of the heat zone A and the first compartment 6a of the cooling zone C each have a plurality of nozzle nozzles 11 for injection on the lower surface thereof. Constitute a hood (10). The first duct 8 and the second air under the nutrition of the positive pressure generated in the hood 10 by the circulation fan 7 and the negative pressure generated outside the hood 10 by the circulation fan 7. It circulates through the duct 9 in the direction previously described, wherein both ends of the first duct 8 open out of the hood 10 and one end of the second duct 9 is preheated. It is open to the inside of the hood 10 in the first compartment (5a). Needless to say, the blower or blowers may be further installed in the middle of the first and / or second ducts (8) and / or (9).

Thus, the workpiece W charged into the preheating zone A through the charging door 12a is preheated in the first compartment 5a by the atmospheric gas of about 510 ° C supplied from the second compartment 5b, where The work piece W is further preheated by a mixed gas of about 600 ° C. which is composed of a high temperature atmospheric gas coming from the first compartment 6a of the cooling table C and a combustion gas coming from the high temperature processing table B. do. Subsequently, the workpiece W is conveyed into the high temperature treatment table B and heated to about 720 ° C. in the high temperature treatment table B.

Subsequently, the workpiece W processed at the high temperature treatment table B is cooled in the first compartment 6a of the cooling table C by the relatively low temperature 420 ° C. atmospheric gas supplied from the second compartment 6b. do. In this first compartment 6a, the temperature of the atmospheric gas is heated to about 720 ° C. at the high temperature treatment table B until the workpiece W is transported into the second compartment 5b of the preheating zone A. The work piece W is raised to about 550 ° C.

Subsequently, the workpiece W is cooled in the second compartment 6b and the third compartment 6c of the cooling table C according to a predetermined cooling curve, and then the cooling table C is discharged through the discharge door 12b. Is discharged from.

4 shows the temperature T1 of the work piece W and the temperature T2 of the atmospheric gas in each compartment or heat treatment table in this case.

Hereinafter, the automatic flow control system of atmospheric gas will be described in detail.

The electrically controlled first damper 14a and the second damper 14b regulate the atmospheric gas circulating in the first duct 8 and the second duct 9 to control the flow rate in the first duct 8. The flow rate in the second duct 9 is the same. This adjustment is made by measuring the flow rate of the atmospheric gas immediately upon detecting the flow rate and temperature in the first duct 8 and the second duct 9.

The automatic control of the flow rate is made based on any one of the two flow rates in the first duct 8 and the second duct 9, and the remaining flow rate is controlled to be equal to the reference flow rate.

Therefore, there is no doubt that the two flow rates are controlled separately so as to be a predetermined one flow rate.

As shown in FIG. 1, FIG. 2, and FIG. 3, the flow volume in the 1st duct 8 is controlled according to the flow volume in the 2nd duct 9. As shown to FIG. In this case, since the processing temperature and cooling rate of the workpiece W are always constant, the atmospheric gas temperature in the first compartment 6a of the cooling table C can be kept constant. Therefore, when the second damper 14b in the second duct 9 is set to primary to allow atmospheric gas to flow at a predetermined flow rate, the flow rate does not change in the second duct 9 from that time. . Therefore, if the flow rate of the first duct 8 is set equal to the flow rate in the second duct 9, heat exchange can effectively occur between the workpiece W and the atmospheric gas.

On the other hand, whenever the heat treatment conditions such as treatment temperature, cooling rate, or the like, and the production capacity of the work piece W are changed, the work piece W emits different thermal energy from the cooling table C. Depending on the environment, the temperature of the atmospheric gas in the cooling table (C) can be changed as necessary. In this case, in some cases, by adjusting the flow rate of the atmospheric gas flowing in the cooling table (C) to correspond to the heat energy emitted from the workpiece (W), it must be effectively recovered.

As shown in Figs. 1, 2 and 3, the flow rate control of the atmospheric gas is based on the above concept or idea.

In this embodiment, the temperature is automatically controlled in the cooling table C to allow the work piece W to be cooled according to a predetermined cooling rate. To this end, by controlling the opening of the second damper 14b by the signal transmitted from the comparator EY, the flow rate of the atmospheric gas is made the optimum flow rate. That is, since the heat energy emitted from the work piece W decreases as the production capacity decreases, the temperature in the cooling table C decreases. Therefore, the second damper 14b is closed by any one of the signals transmitted from the temperature display controllers TIC1, TIC2 and TIC3, and the last compartment of the cooling zone C from the preheating zone A is closed. The flow rate of the low-temperature atmospheric gas supplied toward 6c is reduced.

On the contrary, since the heat energy emitted from the work piece W increases with increasing production capacity, the temperature in the cooling table C rises. As a result, the second damper 14b is further opened, whereby the flow rate of the atmospheric gas is increased.

By controlling the flow rate of the circulating atmospheric gas in the manner as described above to match the heat energy emitted from the work piece W in the cooling table C, the heat energy can be effectively recovered even in a furnace having a large change in production capacity.

In the present embodiment, since the flow rate of the atmospheric gas circulating from the preheating zone A toward the cooling table C through the second duct 9 is automatically controlled according to the production capacity, The flow rate of the atmospheric gas flowing toward the preheating zone A through the one duct 8 is also controlled to match the production capacity.

Note that in this embodiment, the flow rate of the atmospheric gas by the signal transmitted from the heat treatment table showing the greatest variation among the three signals output from the three temperature display controllers TIC1, TIC2 and TIC3. Even if the control is performed, the second damper 14b can be adjusted only by the temperature display controller corresponding to the heat treatment zone where the maximum heat energy is released from the workpiece in advance or the cooling required for the heat treatment is substantially completed. .

It is to be noted that, as shown in FIG. 3, the cooling means 21 for cooling the atmospheric gas supplied into the third compartment 6c of the cooling table C may optionally include the second duct 9. It can be installed on the way.

5 shows an automatic flow control system of a continuous heat treatment furnace according to a second embodiment of the present invention.

In FIG. 5, the automatic flow control system includes a second duct 9a and a fan 22 or a blower communicating with the third compartment 6c of the cooling table C. It can supply into 3rd compartment 6c of the cooling stand C. Therefore, the second duct 9 of the first embodiment communicating with the first compartment 5a of the heating zone A and the last third compartment 6c of the cooling zone C is removed in the furnace of this embodiment. Further, the first damper (TE11) and the differential pressure transducer (DPT11) are installed in the middle of the second duct (9a) to match the flow rate of the air supplied from the fan (22) through the second damper (14b). Control 14a).

In addition, in this embodiment, a third duct 9b is provided in communication with the first compartment 5a of the preheating zone A and having a third damper 14c configured at the open end. In the first compartment 5a of the preheating table A, electrically connected to the electric motor M connected to the third damper 14c, and the pressure in the furnace is determined by the third damper 14c. The pressure control EPC of this kind of furnace may be installed in a conventional combustion furnace or may be installed in this embodiment.

Note that, instead of the direct burner 1, a heating member such as a heat radiating tube of indirect heating means may be used.

It should also be noted that in the above embodiments, although the first, second and third dampers 14a, 14b and 14c are electrically controlled by the electric motor M, they are hydraulic or pneumatic instead. It is possible to use a damper or the like controlled in the manner.

As apparent from the above, according to the present invention, the atmospheric gas heated to a certain temperature through the cooling of the hot work piece W carried from the high temperature treatment table B into the cooling table C0 is cooled in the cooling table C. Air flows in a direction opposite to the direction in which the workpiece W is conveyed by allowing it to flow from the first compartment 6a to the last compartment 5b of the preheating table A through the first duct 8. Thereby preheating the workpiece W, where convection is imparted to the atmospheric gas by the reflux fan 9. Furthermore, both the preheating zone A and the cooling zone C are convection fans on their ceilings. Therefore, since the atmospheric gas in one compartment is not substantially mixed with the atmospheric gas in the adjacent compartment, the temperature of the atmospheric gas in each compartment is determined by the work piece (7). Always higher or lower than the temperature of W) To, after the heat exchange is performed efficiently between the two kinds of temperature can be increased energy savings.

In addition, the second duct 9 or 9a whose one end is connected to the last compartment 6c of the cooling table C is provided with a second damper 14b which is automatically controlled in the middle of the second duct 9 or 9a. The flow rate of the atmospheric gas or air flowing therein can be adjusted to a predetermined flow rate. In addition, a first damper 14a which is automatically controlled by the first duct 8 communicating with the first compartment 6a of the cooling table C and the last compartment 5b of the preheating table A is formed. The flow rate of the atmospheric gas flowing in the first duct 8 can be adjusted to match the flow rate flowing in the second duct 9 or 9a. Such a structure makes it possible to increase energy savings since the excess air gas is never introduced into the high temperature treatment table B and heated.

Claims (2)

High temperature processing table (B) having a heating means (1) therein, preheating table (A) and the other end of the high temperature processing table (B) disposed in connection with one end of the high temperature processing table (B) Cooling table (C), the preheating table (A) and the cooling table (C) is isolated by a plurality of compartments (5a, 5b, 6a, 6b, 6c) each having a convection fan (7) installed on the ceiling In the heat exchange type continuous heat treatment furnace (T), (A) the first duct means (8) for communicating the last compartment 5b of the preheating zone (A) and the first compartment (6a) of the cooling zone (C), (B) the second duct means 9 for communicating the last compartment 6c of the cooling table C with the first compartment 5a of the preheating table A, and (c) the first duct means 8 The second flow control means (14a M, FC) and (d) installed in the middle of the second duct means (9) for adjusting the flow rate of the atmospheric gas flowing in the first duct means (8). 9) second flow control means for adjusting the flow rate of the atmospheric gas flowing in the By configuring (14b, M, EY), the flow is automatically adjusted so that the flow rate of the atmospheric gas introduced into the preheating zone (A) and the flow rate of the atmospheric gas introduced into the cooling zone (C) are automatically adjusted to match each other. Controlled continuous heat treatment furnace. High temperature processing table (B) having a heating means (1) therein, preheating table (A) and the other end of the high temperature processing table (B) disposed in connection with one end of the high temperature processing table (B) Cooling table (C), the preheating table (A) and the cooling table (C) is isolated by a plurality of compartments (5a, 5b, 6a, 6b, 6c) each having a convection fan (7) installed on the ceiling In the heat exchange type continuous heat treatment furnace (T), (A) the first duct means (8) for communicating the last compartment 5b of the preheating zone (A) and the first compartment (6a) of the cooling zone (C), (B) second duct means 9, one end of which is connected to the last compartment 6c of the cooling table C and supplies ambient air into the cooling table C, and (c) the first duct means 8 The first flow control means (14a, M, FC) for adjusting the flow rate of the atmospheric gas flowing in the first duct means (8) and the second duct means (9) in the middle of the second duct means (9) Second flow for regulating the flow rate of air flowing in the duct means 9 By configuring the cutting means 14b, M, and EY, an automatic flow that automatically adjusts the flow rate of the atmospheric gas introduced into the preheating zone A and the flow rate of the air introduced into the cooling zone C to coincide with each other. This controlled continuous heat treatment furnace.

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