DRYING FURNACE AND COATING DRYING METHOD
20230058673 · 2023-02-23
Inventors
Cpc classification
F26B2210/12
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F26B3/04
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F26B15/16
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F26B15/18
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F26B15/12
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
International classification
F26B21/00
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F26B15/16
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F26B15/18
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Abstract
A drying furnace comprises a plurality of drying areas that are continuously provided along a longitudinal direction of the furnace and include a first hot air supply port, a second hot air supply port, and an exhaust port. The first hot air supply port is arranged at a position below a vehicle body in the furnace shell to discharge hot air diagonally upward. The second hot air supply port is arranged at a position higher than the first hot air supply port in the furnace shell to discharge hot air diagonally downward. The exhaust port is arranged at a position lower than the first hot air supply port and the second hot air supply port in the furnace shell to discharge the hot air outside the furnace shell. The drying furnace uniformly raises the temperature of the external and internal parts of the vehicle body while shortening the furnace length.
Claims
1. A drying furnace in which a plurality of drying areas is continuously provided along the longitudinal direction of the furnace, to blow hot air to an vehicle body while being conveyed in the longitudinal direction within a furnace shell, and then to dry a coating film applied to the vehicle body, characterized in that the plurality of drying areas comprises: a first hot air supply port arranged at a position below the vehicle body in the furnace shell to discharge hot air diagonally upward; a second hot air supply port arranged at a position higher than the first hot air supply port in the furnace shell to discharge hot air diagonally downward; and an exhaust port arranged at a position lower than the first hot air supply port and the second hot air supply port in the furnace shell to discharge hot air to the outside of the furnace shell.
2. A drying furnace, according to claim 1, characterized in that the first hot air supply port is arranged at a position of a floor-back level of the vehicle body, and the second hot air supply port is arranged at a window level position of the vehicle body.
3. A drying furnace according to claim 1, characterized in that the first hot air supply port and the second hot air supply port are both configured to include a nozzle, wherein the first nozzle constituting the first hot air supply port is more excellent than the second nozzle constituting the second hot air supply port in terms of attracting action to entrain the surrounding air in the furnace shell.
4. A drying furnace according to claim 1, characterized in that the first hot air supply port and the second hot air supply port are both configured to include a nozzle, wherein the second nozzle constituting the second hot air supply port is more excellent than the first nozzle constituting the first hot air supply port in terms of the action of allowing the hot air to advance straightly.
5. A drying furnace according to claim 1, characterized in that the distance between the inner surface of the furnace shell and the vehicle body is set to be 300 mm or less.
6. A method for drying a coating film applied to a vehicle body by blowing the hot air while the vehicle body is being conveyed in the longitudinal direction in the furnace shell of the drying furnace where a plurality of the drying areas is provided along the longitudinal direction, characterized in that, each of the drying areas comprises: a means by which the hot air is discharged diagonally upward from the first hot air supply port arranged at a position below the vehicle body in the furnace shell, so as to dry the coating film of mainly the external parts including the outer floor side of the vehicle body; another means by which the hot air is discharged diagonally downward from the second hot air supply port arranged at a position higher than the first hot air supply port in the furnace shell, wherein such hot air is introduced into a room through a window of the vehicle body, so as to dry the coating film of mainly the internal parts including inner floor portion of the vehicle body; and yet another means by which the hot air is discharged to the outside of the furnace shell through an exhaust port arranged at a position lower than the first hot air supply port and the second hot air supply port in the furnace shell.
7. A drying furnace according to claim 2, characterized in that the first hot air supply port and the second hot air supply port are both configured to include a nozzle, wherein the first nozzle constituting the first hot air supply port is more excellent than the second nozzle constituting the second hot air supply port in terms of attracting action to entrain the surrounding air in the furnace shell.
8. A drying furnace according to claim 2, characterized in that the first hot air supply port and the second hot air supply port are both configured to include a nozzle, wherein the second nozzle constituting the second hot air supply port is more excellent than the first nozzle constituting the first hot air supply port in terms of the action of allowing the hot air to advance straightly.
9. A drying furnace according to claim 3, characterized in that the first hot air supply port and the second hot air supply port are both configured to include a nozzle, wherein the second nozzle constituting the second hot air supply port is more excellent than the first nozzle constituting the first hot air supply port in terms of the action of allowing the hot air to advance straightly.
10. A drying furnace according to claim 2, characterized in that the distance between the inner surface of the furnace shell and the vehicle body is set to be 300 mm or less.
11. A drying furnace according to claim 3, characterized in that the distance between the inner surface of the furnace shell and the vehicle body is set to be 300 mm or less.
12. A drying furnace according to claim 4, characterized in that the distance between the inner surface of the furnace shell and the vehicle body is set to be 300 mm or less.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0022]
[0023]
[0024]
[0025]
[0026]
[0027]
[0028]
[0029]
MODES FOR CARRYING OUT THE INVENTION
[0030] Hereinafter, the coating drying furnace 11 as an embodiment of the present invention and the coating drying method using the same will be described in detail with reference to
[0031] As shown in
[0032] The furnace body 12 constituting the drying furnace 11 has a rectangular cross-section and a tunnel shape, and an ascending entrance passage 12a, a horizontal conveying passage 12b, and a descending exit passage 12c are arranged along the longitudinal direction of the furnace. An entrance 13 and an exit 14 are provided at both ends of the furnace body 12. That is, a height difference is provided along the longitudinal direction of the drying furnace 11, such that the positions of the entrance 13 and the exit 14 arranged at both ends of the furnace are lower than that of the horizontal conveying passage 12b arranged in the center of the furnace. Then, the automobile body W1 is carried into furnace body 12 from the entrance 13 and is carried out of the exit 14.
[0033] A temperature rising zone 15 is arranged at the first part of the horizontal conveying passage 12b in the furnace body 12 to heat automobile body W1 carried from the entrance 13 by the hot air until the temperature rises up to about 160° C. A temperature holding zone 16 is arranged in the last part of the horizontal conveying passage 12b to dry the automobile body W1 by the hot air while keeping the temperature of the automobile body W1 which has been heated in the conveyance through the temperature rising zone 15. The temperature rising zone 15 is composed of two or more drying areas, and the temperature holding zone 16 is composed of one or more drying areas. Specifically, according to the present embodiment, the temperature rising zone 15 is composed of three drying areas A1, A2, and A3, and the temperature holding zone 16 is composed of one drying area A4.
[0034] As shown in
[0035] As shown in
[0036] Next, the arrangement relationship among the first hot air supply port 41, the second hot air supply port 42, and the exhaust port 43 in the drying furnace 11 of the present embodiment will be described.
[0037] As shown in
[0038] Further, as shown in
[0039] In addition, as shown in
[0040]
[0041] As shown in
[0042] Here, the ratio (quantitative ratio) of the air supplied from the second hot air supply port 42 to the air supplied from the first hot air supply port 41 is not particularly limited and can be set arbitrarily. However, it is preferable to be set, for example, in the range of 3:7 to 5:5. In other words, the ratio of the air supplied from the second hot air supply port 42 is preferably set to the same or less than the ratio of the air supplied from the first hot air supply port 41. Within this range, it is easy to achieve shortening of temperature rising time between external parts and internal parts, and reduction of the difference in temperature rising time (see the graph of
[0043] Next, a method for drying the automobile body W1 by the hot air using the drying furnace 11 of the present embodiment will be described. The graph of
[0044] The automobile body W1 which is an object to be dried is sequentially carried into the furnace body 12 from an entrance 13 by a conveying means at a constant speed. According to the present embodiment, the automobile body W1 is carried in with the door slightly open and passes through and carried out from the drying furnace 11 with the door still slightly open. The automobile body W1 is preheated while passing through the entrance passage 12a. At this time, the temperature of the external parts and the internal parts of the automobile body W1 rises from around 50° C. to 60° C. (see
[0045] The automobile body W1 that has reached the frontmost drying area A1 in the temperature rising zone 15 is exposed to the hot air discharged from the first nozzle 41a of the first hot air supply port 41. At this time, the outer floor side P1 of the automobile body W1 having a large heat capacity is first heated, then the temperature rises. Next, the automobile body W1 that has reached the drying areas A2 and A3 is exposed to the hot air discharged from the first nozzle 41a of the first hot air supply port 41 as well as to the hot air discharged from the nozzle 42a of the second hot air supply port 42. As a result, not only the main external parts including the outer floor side P1 but also the main inner parts including the inner floor side P3 are heated, then the temperature rises. At this time, both the external parts and the internal parts of the automobile body W1 are heated up to the preset temperature of about 160° C. (see
[0046] Similarly, the automobile body W1 that has reached the drying area A4 in the temperature holding zone 16 is also exposed to the hot air discharged from the first nozzle 41a of the first hot air supply port 41 together with the hot air discharged from the second nozzle 42a of the second hot air supply port 42. As a result, the coating film is completely dried and cured while the preset temperature of 160° C. is maintained. After that, the automobile body W1 passes through the exit passage 12c and then is carried out of the furnace from the exit 14.
[0047] Therefore, according to the present embodiment, the following effects can be obtained.
[0048] (1) The drying furnace 11 of the present embodiment is characterized in that the first hot air supply port 41, the second hot air supply port 42, and the exhaust port 43 are arranged at different height positions, as described above, in the plurality of drying areas A1 to A4, respectively. Therefore, when discharging hot air diagonally upward from the first hot air supply port 41 arranged at the lower position of the automobile body W1, the hot air mainly hits the external parts, and the coating film of the external parts is efficiently heated. Further, by discharging hot air diagonally downward from the second hot air supply port 42 arranged at a position higher than the first hot air supply port 41, while the hot air is being discharged from the exhaust port 43 arranged at a position lower than the first hot air supply port 41 and the second hot air supply port 42, the hot air is easily introduced into the room through the window P2 of the automobile body W1. As a result, the hot air from the second hot air supply port 42 mainly hits the internal parts, and the coating film of the internal parts is efficiently heated. Therefore, the heating-up time of the external part and the internal part is shortened, and at the same time, the difference in the heating-up time is reduced. As a result, the temperature of the external parts and the internal parts can be raised efficiently and uniformly, thus making it possible to shorten the length of the furnace. Moreover, according to the present embodiment, heating-up time is shortened, thus making it possible to shorten the length of the temperature rising zone 15 by about 10 m to 20 m.
[0049] (2) According to the drying furnace 11 of the present embodiment, hot air is discharged diagonally upward from the first hot air supply port 41 arranged at the position of the floor-back level L1 of the automobile body W1 so that the coating film of mainly external parts including the outer floor side P1 of the automobile body W1 is efficiently heated, then the temperature rises. Further, hot air is discharged diagonally downward from the second hot air supply port 42 arranged at the position of the window level L2 of the automobile body W1 so that the hot air can be introduced into the room through the window P2 of the automobile body W1. Therefore, the coating film of mainly the internal parts including the inner floor side P3 of the automobile body W1 is efficiently heated, then the temperature rises. Since the exhaust port 43 is arranged at a position lower than the floor-back level L1 of the automobile body W1, high-temperature air does not stay in the upper part of the furnace shell 17. Therefore, it is possible to prevent the quality abnormality of the coating film caused by excessive heating of the upper part of the automobile body W1.
[0050] (3) According to the drying furnace 11 of the present embodiment, the first nozzle 41a constituting the first hot air supply port 41 is more excellent than the second nozzle 42a constituting the second hot air supply port 42 in terms of attracting action to entrain the surrounding air in the furnace shell 17. Thus, using the first nozzle 41a makes it possible to apply a large amount of hot air to the external floor side P1 of the automobile body W1. Therefore, the coating film of mainly the external parts including the eternal floor side P1 of the automobile body W1 is heated more efficiently, thus the temperature rises in a shorter time. On the other hand, the second nozzle 42a constituting the second hot air supply port 42 is more excellent than the first nozzle 41a constituting the first hot air supply port 41 in terms of the action of allowing the hot air to advance straightly. Thus, the hot air can be properly introduced to the room through the window P2 of the automobile body W1, and the hot air can also reach the inner floor side P3 of the automobile body W1 at a relatively distant position and heat it. Therefore, the coating film of mainly the internal parts including the inner floor side P3 of the automobile body W1 is heated more efficiently, then the temperature rises in a shorter time.
[0051] (4) According to the drying furnace 11 of the present embodiment, the second nozzle 42a constituting the second hot air supply port 42 is made such that more than half of the total length is embedded in the furnace shell 17, and that the distance between the portion where the second hot air supply port 42 is formed and the automobile body W1 in the furnace shell 17 is set to be 300 mm or less. With such a configuration, the protrusion of the second nozzle from the furnace shell 17 can be reduced without impairing the straight-advancing action of the hot air from the second nozzle 42a constituting the second hot air supply port. For this reason, the portion where the second hot air supply port is formed in the furnace shell 17 can also be brought close to the automobile body W1, so as to heat the automobile body W1 more efficiently, thus making it possible to raise the temperature in a shorter time. In this embodiment, the distance between the automobile body W1 and any portions other than the portion where the second hot air supply port 42 is formed, is set to be 300 mm or less. As such, the extra space in the furnace shell 17 can be reduced, and the furnace can be totally downsized, thus eventually making it possible to reduce the facility cost and initial cost. Also, downsizing the entire furnace makes it possible to reduce the total air supply volume, the fuel cost, and the running cost. In addition, such a downsizing of the entire furnace makes it possible to reduce the total exhaust air volume, which eventually leads to the reduction of carbon dioxide emissions.
[0052] (5) The drying furnace 11 of the present embodiment has a structure of a mound-shaped furnace such that a part of the heated air in the horizontal conveying passage 12b is returned to the entrance passage 12a by the air supply system 61 and by air supply passage 62, thus reheating the air. Therefore, the heat in the furnace can be efficiently used, thus making it possible to reduce the fuel cost.
[0053] (6) According to the drying furnace 11 of the present embodiment, the second hot air supply port 42 is arranged at the position of the window level L2 of the automobile body W1, and the second nozzle 42a is arranged so as to face diagonally downward. Thus, even when the door is slightly opened, hot air can be properly introduced into the room through the window P2 of the automobile body W1. Therefore, it is unnecessary to open/close the door in the furnace by using e.g., a door opening/closing mechanism (see e.g., JP-A-2005-138037), nor necessary to change the flow direction of the hot air by using a deflector (see e.g., JP-A-2016-125783). This not only contributes to the reduction of equipment costs but also contributes to the downsizing of the entire furnace.
[0054] The embodiment of the present invention may also be modified as follows. [0055] According to the above embodiment, the temperature rising zone 15 is composed of three drying areas A1, A2, and A3, and the temperature holding zone 16 is composed of one drying area A4, but the present invention is not limited to this. For example, the temperature rising zone 15 may be composed of two drying areas or four drying areas or more. Also, the temperature holding zone 16 may be composed of two or more drying areas. [0056] According to the above embodiment, the drying furnace 11 of the present invention is embodied as a mound-shaped furnace, but it may be embodied, for example, as a flat-type furnace. [0057] According to the above embodiment, the automobile body W1 is the object to be dried, but of course, other vehicle bodies (e.g., a train car body or the like) may also be the object to be dried. [0058] According to the above embodiment, the drying furnace 11 of the present invention is embodied as an electrodeposition drying furnace for drying and curing an electrodeposited coating film, but it may also be embodied as a sealer furnace for drying and curing a coating film after under-coating. Yet it may be embodied as a coating drying furnace for drying and curing the coating film after intermediate-coating, under-coating, and top-coating. [0059] According to the above embodiment, the first hot air supply port 41 and the second hot air supply port 42 are arranged in only a single furnace structure in the height direction, but they may also be arranged in plural furnace structures in the height direction. [0060] According to the above embodiment, the nozzle is used as the first hot air supply port 41 and the second hot air supply port 42, but a slit can also be used. [0061] According to the above embodiment, the first nozzle 41a and the second nozzle 42a are symmetrically arranged with respect to the longitudinal direction of the furnace, but they may be arranged asymmetrically. [0062] The first nozzle 41a and the second nozzle 42a may be arranged at a predetermined angle in a predetermined direction to make a rotational flow in the furnace. Yet they may also be arranged at a predetermined angle in a predetermined direction to create a countercurrent flow. [0063] According to the above embodiment, the automobile body W1 which is the object to be dried is continuously conveyed at a constant speed, but the present invention is not limited to this, and cycle conveyance may be applied. Further, in the case of using such a conveyance, the first nozzle 41a may be arranged so as to face the outer floor side P1 or the like of the automobile body W1 which requires a longer temperature rising time. [0064] According to the above embodiment, the air supply/exhaust positions (first hot air supply port 41, second hot air supply port 42, and exhaust port 43) are continuously and regularly provided in the longitudinal direction of the furnace, but the air supply/exhaust positions may not be selectively provided on some sections.
[0065] Besides the technical ideas of the present invention, as described above, other technical ideas to be understood are described hereinafter.
[0066] (1) According to any one of the above aspects 1 to 6, the inside of the furnace is divided into a temperature rising zone and the subsequent temperature holding zone, and the two or more drying areas are arranged in the temperature rising zone, and one or more drying areas are arranged in the temperature holding zone.
[0067] (2) According to any one of the above aspects 1 to 6, the ratio of the amount of air supplied from the second hot air supply port to the amount of air supplied from the first hot air supply port (air volume ratio) is to be set within the range of 3:7 to 5:5.
[0068] (3) According to any one of the above aspects 1 to 6, the exhaust port is arranged in a narrow space located directly under the vehicle body.
DESCRIPTION OF THE REFERENCE NUMERALS
[0069] 1: Drying furnace
[0070] 17: Furnace shell
[0071] 41: First hot air supply port
[0072] 41a: First nozzle
[0073] 42: Second hot air supply port
[0074] 42a: Second nozzle
[0075] 42: Exhaust port
[0076] A1 to A4: Drying area
[0077] L1: Floor-back level
[0078] L2: Window level
[0079] W1: Automobile body as the vehicle body