JP2004271052A - Drying furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drying furnace capable of efficiently raising the temperature of a work with small energy and drying the work in a short time. <P>SOLUTION: This drying furnace 1 dries a surface of the work 2 by blowing the hot air to the conveyed work 2. The drying furnace 1 comprises a furnace shell 3 and a hot air supply duct 11. The furnace shell 3 defines a work conveying space S1. The hot air supply duct 11 is provided with a blowout port 12 for blowing out the hot air to the work conveying space S1. The hot air supply duct 11 is mounted outside the work conveying space S1. The work conveying space S1 is gradually narrowed toward an upper part at least in an upper half area of the furnace shell 3. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a drying furnace for drying the surface of a work by blowing hot air to the work to be conveyed, and particularly has a feature in a shape in the furnace, an installation position of a hot air supply duct, and the like.
[0002]
[Prior art]
Normally, in a car body painting line, after painting while carrying the car body, which is a workpiece, on a conveyor truck, the car body is then transported together with the truck into a high-temperature coating drying oven. To bake and dry the coating. As a drying oven for coating used in such a coating line, a drying oven provided with a radiant heating zone in the former stage and a convective heating zone in the latter stage is conventionally well known (for example, see Patent Document 1).
[0003]
Here, an example of a conventional coating drying furnace 51 is shown. FIG. 3 shows a convection heating zone in the coating drying furnace 51. The furnace shell 52 having a substantially rectangular cross section in the convection heating zone is partitioned by a pair of left and right side walls 53 and an upper wall 54, and a work transfer space S1 is formed therein. A hot air supply duct 56 for supplying hot air is provided at a lower position inside the side wall 53, and an outlet 57 is provided in these hot air supply ducts 56. On the other hand, an exhaust port 58 is provided at the upper part of the furnace shell 52, and an exhaust duct (not shown) and the work transfer space S1 are communicated via the exhaust port 58.
[0004]
In the case of the coating drying furnace 51 configured as described above, the hot air blown out from the outlet 57 collides with the lower end of the side surface of the vehicle body 59 (so-called rocker portion) and then rises along the side surface of the vehicle body 59. At this time, heat is applied to the vehicle body 59 to increase the temperature. As a result, the solvent component evaporates from the coating film on the surface of the vehicle body 59, and the vehicle body 59 is entirely dried. On the other hand, the atmosphere in the furnace is contaminated by containing a large amount of solvent components in the coating film, and the contaminated air (exhaust gas) is sucked from the exhaust port 58 and discharged to the exhaust duct side. In FIG. 3, the flow of the hot air is represented by a curved arrow.
[0005]
[Patent Document 1]
JP-A-2000-334367 (FIGS. 3, 5 and the like)
[0006]
[Problems to be solved by the invention]
By the way, in order to efficiently heat the automobile body 59 by contact with the hot air, for example, the flow rate of the hot air may be increased, and as a specific method, the distance between the inner surface of the furnace shell 52 and the surface of the automobile body 59 is increased. It is thought that it should be as narrow as possible. However, in the conventional coating drying furnace 51, the hot air supply duct 56 is provided at a lower position inside the side wall 53 (that is, at a lower left and right position in the work transfer space S1). Therefore, even if an attempt is made to reduce the distance between the inner surface of the furnace shell 52 and the surface of the vehicle body 59, the presence of the hot air supply duct 56 naturally imposes restrictions. Therefore, conventionally, it has been difficult to improve the hot air flow velocity by narrowing the interval, and therefore, it has not been possible to efficiently heat the automobile body 59.
[0007]
Even if the space can be partially reduced, the cross-sectional shape of the inside of the furnace shell 52 (that is, the cross-sectional shape of the work transfer space S1) when cut along a plane orthogonal to the transfer direction of the vehicle body 59 is substantially rectangular. Due to the shape, a large space 60 is created at the upper left and right positions of the furnace shell 52. That is, focusing on that portion, the distance between the inner surface of the furnace shell 52 and the surface of the automobile body 59 is inevitably increased. Therefore, in the empty space 60, the flow velocity of the hot air becomes slow, and furthermore, the turbulence or stagnation of the hot air flow is likely to occur. Therefore, heat exchange due to contact with the vehicle body 59 is not efficiently performed, and it is also difficult to efficiently heat the vehicle body 59.
[0008]
For the above reasons, conventionally, the automobile body 59 cannot be dried in a short time, and it is necessary to increase the furnace length in order to completely dry the automobile body 59. Along with this, there have been problems such as increased waste of energy and increased running costs.
[0009]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a drying furnace capable of efficiently heating a work with little energy and drying the work in a short time. is there.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, in the invention according to claim 1, in a drying furnace for drying a surface of the work by blowing hot air onto the work to be conveyed, a furnace shell for partitioning a work transfer space; An outlet for blowing hot air is formed in the transfer space, and a hot air supply duct is provided outside the work transfer space, and the work transfer space gradually moves upward in at least an upper half region of the furnace shell. The gist of the present invention is a drying furnace characterized by having a narrow width.
[0011]
Therefore, according to the first aspect of the present invention, since the hot air supply duct is disposed outside the work transfer space, the inner surface of the furnace shell and the surface of the work correspond to the thickness of the hot air supply duct. The interval can be made smaller than before. In addition, since the shape of the work transfer space is gradually narrowed upward in at least the upper half region of the furnace shell, unlike the conventional structure, an empty space that causes airflow turbulence is generated. Disappears. Therefore, the distance between the inner surface of the furnace shell and the surface of the work can be uniformly reduced, and the flow velocity of the hot air flowing along the surface of the work can be increased as a whole without causing disturbance or the like. Can be. Further, since the cross-sectional area of the work transfer space, and thus the total volume of the work transfer space, is reduced, the heating capacity is reduced.
[0012]
As described above, according to the present invention, it is possible to efficiently raise the temperature of a work with little energy, and to dry the work in a short time.
[0013]
The maximum value of the distance between the inner surface of the furnace shell and the surface of the work is preferably about 1 to 2 times the minimum value of the distance between the inner surface of the furnace shell and the surface of the work. More preferably, it is about 1.5 times to 1.5 times. If the interval is set within this range, the flow velocity of the hot air can be reliably increased. In order to reduce the total volume of the work transfer space more reliably, it is desirable that the exhaust duct is also arranged outside the work transfer space.
[0014]
The gist of the invention described in claim 2 is that, in claim 1, the inside surface of at least the upper half region of the furnace shell is a curved concave surface.
[0015]
Therefore, as in the invention described in claim 2, by forming the inner surface of at least the upper half region of the furnace shell as a curved concave surface, for example, the contact resistance with air is reduced as compared with the surface where the bent portion or the like exists. Can be smaller. Therefore, the hot air flows along the curved concave surface while being smoothly guided above the furnace shell. Therefore, turbulence of the hot air can be reliably prevented, and the flow velocity of the hot air can be reliably increased.
[0016]
The gist of the invention described in claim 3 is that, in claim 1 or 2, the hot air supply duct also serves as at least a part of a side wall constituting the furnace shell.
[0017]
Therefore, according to the third aspect of the present invention, since the side wall itself is heated by the hot air, radiant heat is emitted toward the work from the inner side surface of the side wall, and the radiant heat is also used for heating the work. It becomes possible.
[0018]
The height of the hot air supply duct is preferably at least half the height of the furnace shell. Usually, in order to keep the pressure loss small, it is necessary to secure a certain cross-sectional area of the hot air supply duct. Assuming that the hot air supply duct extends along the work transfer direction, the cross-sectional area thereof is determined by the product of the thickness (that is, the dimension along the width direction of the furnace) and the height. Therefore, if the height of the hot air supply duct is set to half or more of the height of the furnace shell, the thickness of the hot air supply duct can be suppressed. Therefore, despite adopting a configuration in which the hot-air supply duct is arranged outside the work transfer space, it is possible to avoid widening the entire furnace. With this configuration, not only the lower part but also the upper part of the work is easily heated by the radiant heat.
[0019]
Here, it is particularly preferable that the drying furnace is a coating drying furnace that dries a coating film on the surface of the vehicle body by blowing hot air onto the conveyed vehicle body. In many cases, a vehicle body represented by an automobile body gradually becomes narrower upward (see FIG. 1 and the like). Therefore, when a workpiece having such a shape is accommodated in the drying oven of the present invention, the distance between the inner surface of the furnace shell and the surface of the workpiece is uniformly reduced. In other words, the coating drying furnace of the present invention exhibits its power most when such a vehicle body is used as a work. Therefore, according to the present invention, the temperature of the vehicle body can be efficiently increased with little energy, and the coating film formed on the surface of the vehicle body can be dried in a short time. Specific examples of such a coating drying furnace include an undercoating furnace for drying the undercoating coating film, an intermediate coating furnace, a topcoating furnace, and the like, and are attached to the surface before being carried into the coating zone and applied. There are draining furnaces for drying and removing water.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
[0021]
[First Embodiment]
Hereinafter, a coating drying furnace 1 according to a first embodiment of the present invention will be described in detail with reference to FIG. FIG. 1 schematically shows a state in which a convection heating zone in a coating drying furnace 1 is cut along a plane orthogonal to a workpiece conveying direction.
[0022]
The coating drying oven 1 of the present embodiment is a drying oven for drying a coating film formed on the surface of the automobile body 2 by blowing hot air onto the automobile body 2 as a work. The coating drying furnace 1 is formed in a tunnel shape having a length of several tens of meters, and has a carry-in port and a carry-out port (both not shown) at both ends. The furnace shell 3 constituting a main part of the coating drying furnace 1 is constituted by a pair of left and right side walls 4, 5 and a floor wall 6, and a work transfer space S1 is formed therein. The periphery of the furnace shell 3 is surrounded by a heat insulating material (not shown). A floor conveyor 7 is laid on the floor wall 6 in the furnace shell 3 so as to extend along the longitudinal direction of the furnace shell 3. A cart 8 is installed on the floor conveyor 7, and the car body 2 is placed on the cart 8 in a horizontal state. The floor conveyor 7 conveys the cart 8 on which the automobile body 2 is placed from the entrance to the exit.
[0023]
In the case of the present embodiment, the pair of left and right side walls 4 and 5 are formed such that the inner side surfaces 4a and 5a are entirely curved concave surfaces, and the curvatures of the inner side surfaces 4a and 5a are also substantially constant. ing. Therefore, the work transfer space S1 defined by the side walls 4 and 5 having such a shape is formed in at least an upper half region of the furnace shell 3 (specifically, a region of about three-half upper half of the furnace shell 3). The width gradually becomes narrower upward. Since the side walls 4 and 5 extend above the work transfer space S1, they also function as upper walls.
[0024]
A hot air supply duct 11 for supplying hot air to the work transfer space S1 is provided at a lower position of the furnace shell 3. The hot air supply duct 11 is disposed outside the work transfer space S1 as a whole. The main surface of the hot air supply duct 11 of the present embodiment (that is, the surface exposed in the work transfer space S1) is a curved concave surface as a whole, and the curvature of the surface is the inner surface 4a of the side walls 4, 5. , 5a. The main surface of the hot air supply duct 11 and the inner side surfaces 4a and 5a of the side walls 4 and 5 are continuous. Therefore, the hot air supply duct 11 of the present embodiment also functions as a part of the side walls 4 and 5 so to speak. The bottom surface of the hot-air supply duct 11 is at the same level as the top surface of the floor wall 6, while the top surface of the hot-air supply duct 11 is located at about 2/5 of the height H1 of the furnace shell 3. That is, the hot-air supply duct 11 has a height H2 that is about 2/5 of the height H1 of the furnace shell 3.
[0025]
A plurality of nozzle-shaped outlets 12 are arranged on the main surface of the hot-air supply duct 11 at predetermined intervals along the work transfer direction (the longitudinal direction of the furnace shell 3). These outlets 12 communicate the hot air supply duct 11 with the work transfer space S1. The tip of the outlet 12 is directed obliquely upward to aim at the locker portion of the vehicle body 2. As a result, hot air of 150 ° C. to 170 ° C. is blown out from the tip of each outlet 12 toward the rocker.
[0026]
On the other hand, a plurality of exhaust ports 13 are provided at a central position in the upper part of the furnace shell 3 at predetermined intervals along the work transfer direction (the longitudinal direction of the furnace shell 3). These exhaust ports 13 are connected to an exhaust duct (not shown) outside the furnace shell 3. Therefore, the contaminated air generated in the work transfer space S1 is discharged from the upper part of the furnace shell 3 to the outside of the furnace through these exhaust ports 13.
[0027]
Next, the operation of the coating drying oven 1 configured as described above will be described.
[0028]
The vehicle body 2, which is a work in the present embodiment, has a cross-sectional shape that becomes gradually narrower as it goes upward. When the vehicle body 2 having such a shape is carried into the convection heating zone, the distance between the inner side surfaces 4a and 5a of the side walls 4 and 5 and the surface of the vehicle body 2 is uniformly reduced. (See FIG. 1). Specifically, the maximum value of the interval is about 1 to 1.3 times the minimum value of the interval, and the difference between the maximum value and the minimum value is extremely small as compared with the related art. Therefore, when hot air is blown from the end of the outlet 12 toward the rocker portion, the hot air moves at a relatively high speed from the lower part to the upper part in the gap. Since the inner side surfaces 4a and 5a of the pair of left and right side walls are curved concave surfaces, the hot air flows while being smoothly guided over the furnace shell 3 along the curved concave surfaces. However, the hot air gradually changes its traveling direction toward the center of the work transfer space S1 as it goes upward. From the above, the hot air having a high flow velocity sufficiently comes into contact with not only both side surfaces but also the upper surface of the vehicle body 2, and heat exchange by the contact between the hot air and the vehicle body 2 is performed efficiently. As a result, the vehicle body 2 is efficiently heated in a short time.
[0029]
Therefore, according to the present embodiment, the following effects can be obtained.
[0030]
(1) In the coating drying furnace 1, the hot air supply duct 11 is arranged outside the work transfer space S1. Therefore, the distance between the inner surfaces 4a and 5a of the side walls 4 and 5 and the surface of the vehicle body 2 can be made smaller than before by an amount corresponding to the thickness of the hot air supply duct 11. In addition, the shape of the work transfer space S1 gradually becomes narrower as it goes upward in at least the upper half region of the furnace shell 3. Therefore, unlike the conventional structure, an empty space that causes turbulence of the airflow does not occur inside the furnace shell 3. Therefore, it is possible to uniformly narrow the interval, and it is possible to increase the flow velocity of the hot air flowing along the surface of the vehicle body 2 without causing disturbance or the like. Further, according to the above configuration, the cross-sectional area of the work transfer space S1, and thus the total volume of the work transfer space S1, is reduced, so that the heating capacity is reduced. Therefore, according to the coating drying furnace 1, the temperature of the vehicle body 2 can be efficiently raised with little energy, and the coating film on the surface of the vehicle body 2 can be dried in a short time. Therefore, it is sufficiently possible to completely dry the automobile body 2 without particularly increasing the furnace length, and it is possible to save energy and reduce running costs.
[0031]
[Second embodiment]
Hereinafter, a coating drying furnace 21 according to a second embodiment of the present invention will be described in detail with reference to FIG. FIG. 2 schematically shows a state in which the convection heating zone in the coating drying furnace 21 is cut along a plane orthogonal to the workpiece transfer direction. Here, only the configuration different from that of the first embodiment will be described, and the common configuration will only be assigned the same member number.
[0032]
As shown in FIG. 2, in the drying oven for coating 21, the structure of the hot air supply duct 22 is different from that of the first embodiment. The height H2 of the hot air supply duct 22 is substantially equal to the height H1 of the furnace shell 3, and the thickness (dimension along the width direction of the furnace) generally increases as the height increases. ing. Therefore, the entire main surface of the hot air supply duct 22 having the curved concave surface functions as the inner surfaces 4a and 5a of the side walls 4 and 5, so to speak, the hot air supply duct 22 is at least partially (accurately) the side walls 4 and 5. Is almost all).
[0033]
Therefore, according to the present embodiment, the following effects can be obtained in addition to the effects of the first embodiment.
[0034]
(1) Since the height H2 of the hot-air supply duct 22 is substantially equal to the height H1 of the furnace shell 3, the pressure loss is maintained at a small value even if the thickness of the hot-air supply duct 22 is considerably reduced. Can be. Therefore, a decrease in the flow velocity of the hot air can be avoided beforehand, and the entire furnace can be prevented from being widened despite the configuration in which the hot air supply duct 22 is arranged outside the work transfer space S1. .
[0035]
(2) Also in the configuration of the first embodiment, radiant heat is emitted from the main surface of the hot air supply duct 11 serving also as the side walls 4 and 5 toward the vehicle body 2, and this radiant heat is Can be used for heating. However, according to the configuration of the hot air supply duct 22 of the present embodiment, not only the lower part but also the upper part of the vehicle body 2 can be heated by radiant heat. Therefore, such radiant heat can be used more effectively, and energy can be further saved.
[0036]
Note that the embodiment of the present invention may be modified as follows.
[0037]
In the above-described embodiment, the inner surfaces 4a and 5a of the pair of left and right side surfaces 4 and 5 and the main surface of the hot air supply duct 22 functioning as the inner surfaces 4a and 5a are curved concave surfaces. A concave shape may be used.
[0038]
In the above-described embodiment, the car body 2 is placed on the carriage 8 accommodated in the work transfer space S1, and the car body 2 is conveyed and dried while being conveyed. However, the present invention is not limited to this. For example, a support column may be protruded from a cart 8 disposed outside the work transfer space S1, a support may be provided at the tip, and the vehicle body 2 may be placed on the support and dried while being transferred. Good.
[0039]
The drying furnace of the present invention may be embodied as a continuous drying furnace that performs drying while transporting a workpiece such as the automobile body 2 at a substantially constant speed, and may also perform drying of the workpiece while repeatedly transporting and temporarily stopping the workpiece. It may be embodied as a batch drying oven to be performed.
[0040]
In the above embodiment, the present invention is embodied as the drying furnaces 1 and 21 for drying the automobile body 2, but is not limited to this. For example, the present invention may be embodied as a drying furnace for drying a vehicle body other than the automobile body 2 such as a train body. Further, the present invention may be embodied as a drying furnace for drying an object other than the vehicle body (particularly, a large and heavy work such as a vehicle).
[0041]
Next, in addition to the technical ideas described in the claims, technical ideas grasped by the above-described embodiments will be listed below.
[0042]
(1) A drying method using the drying furnace according to any one of claims 1 to 4, wherein a maximum value of a distance between an inner surface of the furnace shell and a surface of a work is determined by an inner surface of the furnace shell. A drying method characterized in that the distance is set to 1 to 2 times the minimum value of the distance between the workpiece and the surface of the work. Therefore, according to this technical idea, the flow velocity of hot air can be reliably increased.
[0043]
(2) The drying furnace according to claim 3, wherein the height of the hot air supply duct is equal to or more than １ ／ of the height of the furnace shell.
[0044]
(3) The drying furnace according to claim 3, wherein the height of the hot air supply duct is not less than 2/3 of the height of the furnace shell.
[0045]
(4) In a drying furnace for drying the surface of the work by blowing hot air onto the work to be conveyed, a furnace shell defining a work transfer space and an outlet for blowing hot air into the work transfer space are formed. A drying oven, comprising: a hot air supply duct disposed outside a transfer space; and an inner surface in at least an upper half region of the furnace shell is concave.
[0046]
(5) Hot air, which can be used in a drying furnace for drying a workpiece by using hot air, has an outlet on a main surface exposed to the furnace space, and has a concave main surface. Supply duct structure. Therefore, according to this technical idea, the drying furnace according to any one of claims 1 to 3 has a structure suitable for realizing the drying furnace.
[0047]
(6) It can be used in a drying furnace for drying a workpiece by using hot air, has a blowout port on a main surface exposed to the furnace space, has a curved concave surface, and has a thickness. The hot air supply duct structure is characterized in that the size of the hot air supply duct increases as it goes upward. Therefore, according to this technical idea, it has a structure particularly suitable for realizing the drying furnace according to claim 3 or 4.
[0048]
【The invention's effect】
As described in detail above, according to the first to fourth aspects of the present invention, it is possible to provide a drying furnace that can efficiently raise the temperature of a work with little energy and can dry the work in a short time. it can.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view illustrating a coating drying furnace according to a first embodiment of the present invention.
FIG. 2 is a schematic sectional view showing a coating drying furnace according to a second embodiment.
FIG. 3 is a schematic sectional view showing a conventional drying oven for coating.
[Explanation of symbols]
1, 21 ... Coating drying furnace 2 as a drying furnace 2 ... Automotive body 3 as a work 3 ... Shell 4,5 ... Side wall 11,22 ... Hot air supply duct 12 ... Outlet S1 ... Work transfer space H1 ... Height of the furnace shell Height H2: Height of hot air supply duct

Claims (4)

In a drying furnace for drying the surface of the work by blowing hot air to the work to be conveyed,
A furnace shell for partitioning the work transfer space;
An outlet for blowing hot air is formed in the work transfer space, and a hot air supply duct is provided outside the work transfer space.The work transfer space goes upward in at least an upper half region of the furnace shell. A drying oven characterized in that the width gradually becomes narrower. The drying furnace according to claim 1, wherein an inner side surface of at least an upper half region of the furnace shell is a curved concave surface. 3. The drying furnace according to claim 1, wherein the hot-air supply duct also serves as at least a part of a side wall that forms the furnace shell. 4. The said drying furnace is a coating drying furnace which dries the coating film on the surface of the said vehicle body by blowing a hot air on the vehicle body conveyed, The coating furnace of any one of Claims 1 thru | or 3 characterized by the above-mentioned. Drying oven.

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