JP2004107706A - Air blowing method of heat treatment furnace, and heat treatment furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air blowing method in the heat treatment for rapidly raising the temperature of works, and uniformly heating or cooling the works. <P>SOLUTION: A pair of works W and W are arranged on a downwind side of an axial flow fan 9 disposed on a furnace top with a ventilation space S therebetween, and the air flow F1 by the axial flow fan 9 is fed toward the air-passing space S. Since the air flow F1 passes through the ventilation space S and is circulated to form air flows F2 and F3 along surfaces of the pair of works, the air flows F1, F2 and F3 uniformly work on each of the pair of works W and W. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for blowing a heat treatment furnace and a heat treatment furnace suitable for gas heating and gas cooling of an object to be treated.
[0002]
[Prior art]
For example, when performing a heat treatment such as annealing, in a continuous heat treatment furnace, or in a batch-type heat treatment furnace, an object to be treated is arranged in the furnace, and a centrifugal or axial-flow stirring fan provided in the furnace. By flowing a heating gas in a furnace, the object to be treated is heated to a required temperature and further uniformly heated (for example, see Patent Documents 1 and 2).
[0003]
Also, in the case of cooling processing of the object to be processed, uniform cooling is performed by forcibly convection the cooling gas in the furnace with a stirring fan (see Patent Document 3).
[0004]
[Patent Document 1]
JP-A-5-26587 [0005]
[Patent Document 2]
JP-A-5-203371
[Patent Document 3]
JP, 2000-87136, A A heating gas and a cooling gas (hereinafter, simply called “heating gas”) heat and cool (hereinafter, simply, “heating”) the object to be processed by the centrifugal stirring fan. The heating gas is diffused in the circumferential direction of the stirring fan, the heating gas is not vigorously applied to the processing object, there is also a pressure loss, and the processing object is relatively slowly and uniformly heated. However, there is a problem in that it takes time to raise the temperature to a temperature that requires.
[0007]
On the other hand, in the case of the axial flow type stirring fan, the heating gas is supplied vigorously toward the blast of the fan, the diffusion is small, and therefore, by applying the heating gas to the processing object, the heating gas is applied to the processing object. Heating can be accelerated. However, it is difficult to uniformly apply the heating gas to the object to be processed, and a problem remains in uniform heating of the entire object to be processed. In other words, there remains a problem that the quality of the processing object is likely to be uneven due to uneven heating and heating of the processing object.
[0008]
[Problems to be solved by the invention]
In the heat treatment, the shortening of the heating time and the cooling time (hereinafter simply referred to as “heating time”) has a great effect on economic effects such as a reduction in energy consumption as well as a reduction in the total operation time. Further improvements are desired. The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a method for blowing a heat treatment furnace and a heat treatment furnace, in which a heating time of a processing target by a heating gas is reduced while maintaining a uniform heating state. Is what you do.
[0009]
[Means for Solving the Problems]
In order to solve the above problem, the blowing method of the heat treatment furnace according to the present invention, on the downwind side of the axial flow fan arranged on the furnace ceiling, arrange a pair of processing objects with a ventilation space between each other, The airflow from the axial fan is supplied to the ventilation space (claim 1).
[0010]
According to this configuration, the airflow supplied by the axial fan flows through the ventilation space and vigorously circulates and circulates along the surfaces of the pair of objects to be processed. It acts uniformly on each of the processing objects.
[0011]
An air blowing method for a heat treatment furnace according to one embodiment of the present invention includes supplying an airflow with an axial fan toward the ventilation space of a pair of processing objects arranged in the furnace with a ventilation space therebetween. An airflow is generated that circulates in the opposite directions to the respective outer circumferences of the pair of processing objects (claim 2).
[0012]
As a preferred embodiment, in the method, the pair of processing objects are reciprocated in the width direction of the ventilation space with a stroke smaller than the width of the ventilation space while supplying the airflow to the ventilation space. It is characterized by having (Claim 3). This is very preferable because the airflow from the axial fan comes into contact with the entire surfaces of the pair of processing objects more reliably.
[0013]
Further, the heat treatment furnace according to the present invention, the lower part of the axial fan disposed on the furnace ceiling is a stay position of a pair of objects to be processed with a ventilation space therebetween, the ventilation space, the axial fan It is characterized in that it is an air flow supply path from the outside (claim 4). According to such a heat treatment furnace, since the airflow from the axial fan circulates and circulates along the surfaces of the pair of processing objects through the ventilation space, the airflow from the axial fan is reduced. , And uniformly act on each of the pair of processing objects.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings.
[0015]
FIG. 1 is a longitudinal sectional view of a main part of a heat treatment furnace according to one embodiment of the present invention, FIG. 2 is a longitudinal sectional view of a heat treatment furnace according to one embodiment of the present invention, and FIG. FIG. 4 is a comparison diagram of a heating rate according to a difference between a fan shape and a rotation speed.
[0016]
The heat treatment furnace 1 is a tempering furnace for performing, for example, annealing. The heat treatment furnace 1 includes a furnace main body 3 having a charging port 2 for charging a workpiece W such as a steel part, and a door 4 for opening and closing the charging port 2.
[0017]
In the processing chamber 5 defined in the furnace main body 3, rollers 6 as transport means for carrying the object to be processed W and guiding it into the furnace main body 2 are arranged with a predetermined space therebetween. Is established. The processing object W is placed on a tray 7 and supplied from the loading port 2 onto the roller 6. The roller 6 is operatively connected to a drive source (not shown). In the drawings, a roller hearth type is used as the conveying means, but the present invention is not limited to this, and a tray pusher type conveying means may be employed.
[0018]
On both sides of the inside of the furnace main body 3, direct fire burners 8 are provided as heat sources for heating the supplied gas. However, the heat source may be of another type such as a so-called radiant tube.
[0019]
An axial fan 9 is disposed in the processing chamber 5 defined in the furnace main body 3 as a fan for circulating the heating gas. In the present embodiment, the axial fan 9 is disposed on the ceiling of the furnace main body 3 via the rotating shaft 10.
[0020]
In the drawing, reference numeral 14 denotes a centrifugal fan disposed behind the axial fan 9 in the processing chamber 5, and the centrifugal fan 14 has a uniform processing target W heated to a required temperature by the axial fan 9. Has the function of maintaining heating. Reference numeral 15 denotes a front purge chamber, 16 denotes an oil tank, 17 denotes a rear purge chamber, and 18 denotes an outlet conveyor.
[0021]
The axial fan 9 is driven to rotate by a motor 11 as a prime mover, and sends out the heated gas in the processing chamber 5 downward in parallel with the axial direction of the rotating shaft 10. As a result, the heating gas passes through the gap between the rollers 6, hits the floor surface 12 of the furnace body 3, flows upward while spreading radially outward, and is sucked into the axial fan 9. You.
[0022]
Thus, in the processing chamber 5 defined by the furnace main body 3, by the rotation of the axial fan 9, the downward airflow F 1 along the rotation axis of the axial fan 9 and the floor surface 12, A circulating airflow is generated that includes an airflow F2 that spreads radially outward and an upward airflow F3 that is sucked from the lower part of the processing chamber 5 into the intake area 13 above the axial fan 9.
[0023]
In the present invention, a pair of processing objects W, W, each of which is formed into a block, is charged into the processing chamber 5 defined in the furnace main body 3, and heat treatment is performed. The pair of processing objects W, W are provided with a ventilation space S of an appropriate width between them, and the ventilation space S is positioned directly below the axial fan 9 so that the processing chamber 5 It is allowed to stay inside when the temperature rises.
[0024]
When the axial fan 9 is rotated, a part G1 of the heated gas in the processing chamber 5 heated by the direct-fire burner 8 is blown onto the upper surfaces of the pair of processing objects W, W. Can be At the same time, another part G2 of the heating gas flows downward through the ventilation space S by the blowing action of the axial fan 9 (F1).
[0025]
Thereafter, the heating gas spreads radially on the floor surface 12 (F2), heats the bottom, turns upward (F3), and is sucked into the intake area 13 of the axial fan 9.
[0026]
Similarly, the airflow G <b> 1 hitting the upper surfaces of the pair of processing objects W, W expands laterally and rises, and is sucked into the intake area 13 of the axial fan 9. The air flow circulating in this manner contacts the respective surfaces of the pair of processing objects W, W without evenness. As a result, each of the pair of processing objects W, W is rapidly heated while being uniformly heated.
[0027]
In particular, since the axial fan 9 is used as the circulation fan, the airflows G1 and G2 have momentum, a large air volume is obtained, and the pressure loss is small, so that the time required for temperature rise can be reduced. It is desirable that the ventilation space S has a width smaller than the effective ventilation width of the axial fan 9.
[0028]
Further, it is desirable that the tray 7 be made of a gas-permeable tray or the like so that the heating gas can effectively contact the lower surfaces of the processing objects W and W. Further, a rectifying means having a rectifying surface for smoothly diffusing the air flow F1 descending through the ventilation space S radially and guiding it as the air flow F2 is provided on the floor surface 12 in the furnace main body 3. It can also be set up.
[0029]
In the case of a tray pusher type heat treatment furnace, a spacer (not shown) that forms a space corresponding to the ventilation space S between the trays 7, 7 is used, so that the pair of processing objects W, W The ventilation space S can be formed between them.
[0030]
Furthermore, it is desirable to perform the heat treatment while controlling the operation of the roller 6 so that the pair of processing objects W, W are simultaneously reciprocated in the same direction with a stroke s smaller than the width of the ventilation space S. . In this way, the contact of the heating gas to all surfaces of the pair of processing objects W, W is further ensured, soaking is further improved, and the temperature rise is accelerated.
[0031]
According to the air blowing method of the present invention, the individual processing objects W, W are rapidly heated while being uniformly heated, so that the operation time such as annealing can be shortened. Therefore, a high-quality heat-treated product can be obtained in a short time regardless of whether it is a continuous type or a batch type, which is preferable.
[0032]
FIG. 3 shows the results of the comparative experiment. In the drawing, A is a temperature rise curve at 6 points in the tray in the furnace according to the present invention, and B is a temperature rise curve at 6 points in the tray in a conventional furnace using a centrifugal (sirocco) fan. From the viewpoint of minutes, in the furnace according to the present invention, each part of the tray, including the bottom, is rapidly heated to about 800 ° C. in a relatively small variation state, whereas in the conventional furnace using a centrifugal fan, Each part of the tray was finally around 600 ° C, and under the same conditions, the time required to reach the soaking temperature of 880 ° C plus or minus 5 ° C was 103 minutes from the charging in the case of the furnace using the conventional centrifugal fan. In contrast, in the case of the furnace according to the present invention, it took 46.5 minutes from the charging. That is, it was confirmed that the heating time could be reduced to about one half.
[0033]
FIG. 4 shows the results of another comparative experiment. This figure is a comparison diagram of the heating rate due to the difference in the fan shape and the difference in the number of rotations. It has been found that when the number of revolutions is changed, increasing the number of revolutions increases the rate of temperature rise.
[0034]
Further, in the present invention, it has been confirmed that the temperature of the furnace upper part is significantly reduced as compared with the conventional furnace using a centrifugal fan, so that the radiant heat is small and the energy loss is small. It seems to have contributed partly to
[0035]
In this embodiment, the case of gas heating has been described as an example. It is needless to say that the object to be processed can be cooled quickly and uniformly in this case.
[0036]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the blowing method and the heat treatment furnace of the heat treatment of this invention, shortening of the temperature rise time of an object to be processed can be performed, maintaining a uniform heating state. The effect is economical.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a main part of a heat treatment furnace according to one embodiment of the present invention.
FIG. 2 is a longitudinal sectional view of a main part of a heat treatment furnace according to one embodiment of the present invention.
FIG. 3 is a comparison diagram of a temperature rise curve.
FIG. 4 is a diagram illustrating a heating rate comparison diagram based on a difference in fan shape and rotation speed.
[Explanation of symbols]
3 Furnace (furnace body)
9 Axial fan S Ventilation space s Stroke (reciprocating width)
W Processing object F1, F2, F3 Airflow

Claims (4)

A pair of processing objects is arranged below the axial fan disposed on the ceiling with a ventilation space therebetween, and an airflow by the axial fan is supplied toward the ventilation space. , Heat treatment furnace blowing method. An airflow is supplied by an axial fan toward the ventilation space of the pair of processing objects arranged in the furnace with a ventilation space therebetween, and the outer peripheries of the pair of processing objects are turned in opposite directions to each other. A method for blowing air in a heat treatment furnace, characterized by generating a circulating air flow. The method according to claim 1, wherein the pair of processing objects are reciprocated in a width direction of the ventilation space with a stroke smaller than a width of the ventilation space while supplying the airflow to the ventilation space. 4. The blowing method of the heat treatment furnace according to 4. The lower part of the axial fan arranged on the ceiling portion is set as a stay position of a pair of processing objects having a ventilation space between them, and the ventilation space is used as a supply path of airflow from the axial fan. And a heat treatment furnace.

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