Drying oven

Abstract

An object of the present invention is to provide a drying furnace A that is a compact device, which promotes drying of the workpieces and can dry the workpieces efficiently. [Solution] The drying furnace A of the present invention is a drying furnace A for drying workpieces W, and comprises a furnace body 10 having a drying chamber 11 covered with an insulating wall B, a heat source 20 that radiates infrared rays into the drying chamber 11, a duct 30 provided within the drying chamber 11 that sends air from the upper part of the drying chamber 11 to the lower part of the drying chamber 11, and a fan 40 that draws in air from the upper part of the drying chamber 11, blows it into the duct 30, and sprays it into the lower part of the drying chamber 11.

Description

[Technical Field]

[0001] The present invention relates to a drying oven, and more particularly to a drying oven for drying a coating on a painted object. [Background technology]

[0002] In a conventional drying oven, the heating method is to raise the temperature inside the oven by generating hot air using a gas burner or an electric heater and a blower fan.

[0003] The workpiece to be dried, such as a painted object (hereinafter simply referred to as "workpiece"), is heated with hot air, which makes it difficult for the temperature of the workpiece to rise, resulting in a long drying time and making the system less energy-efficient.

[0004] Furthermore, in the case of a continuous oven, the length of the drying oven becomes long, which poses a problem of requiring a large installation space in the factory.

[0005] Furthermore, Patent Document 1 discloses a drying furnace that combines heating by radiation and heating by hot air. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 11-221513 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the drying furnace shown in Patent Document 1 above relates to a drying furnace for drying paint applied to box-shaped workpieces such as automobiles, and since the floor of an automobile body uses thicker steel plates than the side panels and roof, the temperature rise of the floor is slower, and to solve the problem that the paint in the center of the underside of the automobile body is the most difficult to dry, a radiant heat drying means consisting of a radiant heat generating unit that generates radiant heat, a circulation duct connected to the radiant heat generating unit, and a circulation fan and heater arranged in the middle of the circulation duct is used to dry the side panels and roof of the automobile body, and a hot air drying means consisting of an intake port provided at the top of the left and right side walls of the housing, an intake fan attached to the intake port, an air supply duct arranged outside the housing that sends the heated air sucked in by the intake fan, an air supply pipe connected to the outlet side of the air supply duct, and an outlet (nozzle) attached to the air supply pipe actively sucks in the hot air generated by the radiant heat drying means, and the hot air sprayed upward from the nozzle directly heats and dries the automobile body floor.

[0008] The housing of the drying oven has a space surrounded by a heat-insulating wall containing a heat insulating material. In the drying oven disclosed in Patent Document 1, an air supply duct is disposed outside the housing, which makes it prone to heat loss and also makes the oven large-scale.

[0009] The present invention has been made in consideration of the above points, and aims to provide a drying furnace that reuses infrared energy that could not be absorbed by the workpiece, is a compact device, promotes drying of the workpiece, and can dry the workpiece efficiently. [Means for solving the problem]

[0010] The present invention includes the embodiments shown below.

[0011] [1] A drying furnace for drying workpieces, comprising: a furnace body having a drying chamber covered with insulating walls; a heat source that radiates infrared rays into the drying chamber; a duct provided in the drying chamber that sends air from the upper part of the drying chamber to the lower part of the drying chamber; and a fan that sucks in air from the upper part of the drying chamber, blows it into the duct, and sprays it into the lower part of the drying chamber.

[0012] The drying oven [1] can quickly and uniformly heat the interior of the drying chamber by transporting the hot air heated by the heat source inside the drying chamber through a duct to the bottom of the drying chamber. In addition, since the hot air exchanges heat with the air inside the drying chamber while flowing through the duct installed inside the drying chamber, the interior of the drying chamber can be heated efficiently.

[0013] [2] The drying furnace according to [1] above, wherein the upper end of the heat source is lower than half the height of the drying chamber.

[0014] In the drying furnace [2], the upper end of the heat source is positioned lower than half the height of the drying chamber, which prevents the upper part of the chamber from overheating and allows the drying chamber to be heated evenly.

[0015] [3] A drying furnace according to [1] above, in which a plurality of the heat sources are arranged opposite each other inside the drying chamber, and a heat source moving unit is provided to change the distance between the opposing heat sources.

[0016] The drying oven [3] can irradiate infrared rays at the appropriate position for workpieces of various sizes.

[0017] [4] The drying furnace according to [1] above, wherein the surface of the duct facing the drying chamber forms a reflective surface that reflects the infrared rays.

[0018] The drying furnace [4] can reflect infrared rays that were not irradiated onto the workpiece or that were reflected by the workpiece in the duct, allowing them to be irradiated onto the workpiece again or to contribute to raising the temperature inside the drying chamber.

[0019] [5] A drying furnace as described in [1] above, comprising a duct forming member provided on the drying chamber side of the insulating wall and forming the duct between the insulating wall and the duct forming member, the duct forming member being made of a metal material.

[0020] In the drying oven [5], the heat of the air flowing through the duct is more easily transferred to the drying chamber. In other words, the heat is more easily transferred to the drying chamber side than to the insulated wall side, making it less likely for heat to leak outside the room. [Effects of the Invention]

[0021] According to the present invention, the heating method for the workpieces is a combination of an infrared heater and the circulation of hot air inside the furnace heated by the thermal energy of the infrared heater, and by converting the energy of the heat source that was not received by the workpieces into hot air inside the furnace, the temperature inside the furnace is increased, which leads to the promotion of drying of the workpieces and enables efficient drying. In other words, by combining the heat source that is irradiated onto the workpieces and the hot air inside the furnace generated by the thermal energy that was not received by the workpieces, thermal efficiency is increased and energy saving effects are improved.

[0022] In addition, since a duct for circulating the heated warm air inside the oven is installed inside the drying chamber, the heat of the warm air flowing through the duct is less likely to leak outside the drying chamber, which increases thermal efficiency and makes the device more compact than if it were installed outside the drying chamber. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a front view of a drying furnace according to a first embodiment of the present invention. [Figure 2] FIG. 1 is a side view showing the appearance of a drying furnace according to a first embodiment of the present invention; [Figure 3] FIG. 1 is a front cross-sectional view showing the internal structure of a drying furnace according to a first embodiment of the present invention. [Figure 4] FIG. 1 is a plan view of a drying furnace according to a first embodiment of the present invention. [Figure 5] FIG. 1 is a schematic perspective view showing a part of the interior of a drying furnace according to a first embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0024] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the drying furnace according to the present invention will now be described in detail with reference to the accompanying drawings. [Example]

[0025] 1 to 5 show a drying furnace A of the first embodiment, and as shown in FIGS. 3 and 5, the drying furnace A dries a workpiece W suspended therein.

[0026] The drying oven A is mainly composed of an oven body 10, a heat source 20, a duct 30, and a fan 40.

[0027] The furnace body 10 is composed of an insulating wall B and a drying chamber 11 covered by the insulating wall B. The insulating wall B is composed of four insulating side walls B1, an upper insulating top plate B2, and a lower insulating bottom plate B3, each of which is made of insulating material, and the drying chamber 11 is formed by the space surrounded by the insulating wall B inside.

[0028] The heat source 20 uses a heat source that emits infrared rays, such as a halogen heater, and irradiates the infrared rays onto the workpiece W suspended in the drying chamber 11. As shown in Figures 3 and 5, the heat source 20 is configured by arranging multiple rod-shaped heat sources 20 horizontally and lining them up in the vertical direction (up and down).

[0029] 3 and 5, a plurality of heat sources 20 arranged in parallel in the vertical direction are arranged facing each other as two rows of heat sources 20a, 20b. A workpiece W is suspended between these two rows of heat sources 20a and 20b arranged in the vertical direction, and infrared rays are irradiated onto the workpiece W from these heat sources 20a, 20b to dry the workpiece W. A reflector 23 is provided on the side of the heat insulating side wall B1 of the heat source 20. The reflector 23 reflects the infrared rays radiated from the heat source 20 toward the side of the heat insulating side wall B1 and irradiates them onto the workpiece W.

[0030] Furthermore, the heat source 20 is provided at its lower end with a heat source moving section 22 (heat source moving rollers 22a, heat source moving rails 22b) that changes the distance between the opposing heat sources 20a, 20b, so that the two rows of opposing heat sources 20a, 20b can move in opposing directions. With this configuration, the drying furnace A can narrow or widen the distance between the heat sources 20a, 20b to accommodate workpieces W of various sizes, and infrared rays can be irradiated at an appropriate position on the workpieces W.

[0031] The upper end of the heat source 20 is preferably positioned lower than half the height of the drying chamber 11. Here, the height of the drying chamber 11 refers to the ceiling surface of the drying chamber 11, and the lower end refers to the position of the heat source moving roller 22a that moves the workpiece W. In Figure 4, symbol B4 denotes an explosion vent B4 that opens when high pressure is generated inside the drying chamber 11. By positioning the upper end of the heat source 20 lower than half the height of the drying chamber 11, the drying furnace A can prevent the upper part of the drying chamber 11 from overheating, thereby achieving uniform heating within the drying chamber 11 and reducing the risk of overheating. The upper end of the heat source 20 is preferably positioned lower than half the height of the effective drying range that allows safe and normal drying of the workpiece W in the drying furnace A. This allows the workpiece W to be heated uniformly.

[0032] Moreover, it is preferable to arrange the heat source 20 so that its lower end is located lower than the lower end of the workpiece W. By arranging the heat source 20 in this manner, the workpiece W can be heated uniformly.

[0033] The duct 30 is provided in the drying chamber 11 and serves to send air from the upper part of the drying chamber 11 to the lower part of the drying chamber 11. The fan 40 serves to suck air from the upper part of the drying chamber 11 through an intake port 31a that opens at the top of the drying chamber 11, send it to the duct 30, and spray it toward the lower part of the drying chamber.

[0034] The duct 30 is composed of an upper duct 31, a side duct 32, and a lower duct 33. The upper duct 31 is disposed on the underside of the insulating top plate B2 of the furnace body 10. That is, the upper duct 31 has an intake port 31a in the ceiling portion of the drying chamber 11 that draws in air from within the drying chamber 11. This intake port 31a is located directly above the workpiece W and opens downward. An intake port of a fan 40 is disposed above the intake port 31a.

[0035] The side duct 32 is arranged along the inner surface of the heat insulating side wall B1, communicating with the upper duct 31. In this embodiment, the side duct 32 is provided between the heat insulating side wall B1 and the heat sources 20a and 20b.

[0036] The lower duct 33 is connected to the side duct 32 and is disposed on the upper surface of the insulating bottom plate B3, and is disposed horizontally at the lower end of the side duct 32 so as to be located below the heat sources 20a, 20b, with an ejection port 33a at its tip. In this embodiment, the lower duct 33 passes through an opening 25 provided between the supports 24 that support the heat sources 20a, 20b, and protrudes toward the workpiece W side beyond the heat sources 20a, 20b. As a result, the ejection port 33a of the lower duct 33 is located closer to the workpiece W than the heat sources 20a, 20b.

[0037] Furthermore, the surface of the duct 30 facing the drying chamber 11 preferably serves as a reflective surface that reflects infrared rays emitted from the heat source 20. To maximize its effectiveness, the reflective surface is preferably polished with an abrasive of 200 or higher grit, more preferably with an abrasive of 400 or higher grit. The surface roughness of the reflective surface is preferably 0.5 μm or less, more preferably 0.2 μm or less. This configuration allows the drying furnace A to reflect infrared rays that were not irradiated onto the workpieces W or that were reflected by the workpieces W, thereby allowing the reflected infrared rays to be re-irradiated onto the workpieces or contribute to increasing the temperature inside the drying chamber. While there is no particular lower limit for the surface roughness of the reflective surface, a surface roughness of 0.02 μm or more is preferred from the standpoint of economic efficiency in forming the reflective surface. Here, the surface roughness refers to the arithmetic mean roughness Ra defined in JIS B 0601-2001.

[0038] Furthermore, it is preferable that the duct 30 provided on the drying chamber 11 side of the insulating wall B has a duct-forming member that forms the duct 30 between the insulating wall B and the duct 30. A suitable metal material is, for example, a metal plate such as stainless steel (e.g., SUS304) or aluminum, and the duct 30 is formed by bending this metal plate. This configuration allows the drying furnace A to transfer heat from the air flowing through the duct 30 more easily into the drying chamber 11 than out of the drying chamber 11. In other words, because heat is transferred more easily to the drying chamber 11 side than to the insulating wall B side, the thermal energy generated by the heat source 20 is less likely to leak out of the drying chamber, improving thermal efficiency and saving energy.

[0039] Furthermore, as described above, all of the ducts 30 are arranged so as to protrude inside the insulating wall B, so that they can perform heat exchange into the drying chamber 11, and since they do not protrude outside the furnace body 10, the entire drying furnace A has a compact and smart configuration.

[0040] The fan 40 is installed in the upper duct 31 located under the center of the insulating top plate B2 of the furnace body 10, and is driven to rotate by a motor 41 installed above the insulating top plate B2 of the furnace body 10. The fan 40 is preferably a sirocco fan, which has the advantage of not taking up much space because it draws air from the upper part of the drying chamber 11 in the direction of the rotation axis of the motor 41 and blows air vertically from the direction of the rotation axis of the motor 41, i.e., horizontally within the upper duct 31.

[0041] With the above configuration, as shown in Figure 3, the air from the upper part of the drying chamber 11 sucked in by the fan 40 passes through the upper duct 31 in the direction indicated by arrow a, passes through the side duct 32 in the direction indicated by arrow b, passes through the lower duct 33 in the direction indicated by arrow c, is blown from the outlet 33a of the lower duct 33 to the lower part of the drying chamber 11, and is blown from the bottom to the top of the work W in the direction indicated by arrow d.

[0042] Therefore, the drying oven A has the effect of sending the hot air heated by the heat source 20 and rising inside the drying chamber 11 to the lower part of the drying chamber 11 through the duct 30, and by causing this hot air to rise, quickly and uniformly raising the temperature of the entire inside of the drying chamber 11. In addition, while the hot air drawn in by the fan 40 flows through the duct 30 provided inside the drying chamber 11, the hot air inside the duct 30 exchanges heat with the air inside the drying chamber 11, which has the effect of efficiently heating the inside of the drying chamber 11.

[0043] For example, in a gas furnace that uses gas as a heat source, an in-furnace temperature of 180°C to 200°C is required to achieve a work temperature of 180°C to 200°C, whereas in the drying furnace of the present invention, the in-furnace temperature can be set to 160°C to achieve a work temperature of 180°C to 200°C, resulting in good thermal efficiency, reduced thermal energy consumption, and energy savings.

[0044] The energy used in the painting and drying processes accounts for approximately 25% of the total energy used in the manufacturing process, so if we can save a large amount of energy, it will be a shortcut to becoming carbon neutral.This invention has the advantages of reducing CO2 emissions, shortening drying time, and improving work efficiency.The thermal energy received by the workpiece and in the drying chamber 11 is returned to the ambient temperature and circulated, resulting in energy savings.

[0045] The infrared heater used as the heat source for the drying oven of this invention has a fast start-up time and quickly reaches the appropriate temperature when switched on, allowing for localized heating in a short amount of time, supporting rapid work. The infrared heater's output can also be finely adjusted using a digital control panel. Furthermore, while infrared heaters have the disadvantage of easily raising the temperature of the irradiated surface, they have difficulty raising the temperature of the backside. However, this disadvantage can be eliminated by combining them with the effect of hot air circulation, which is excellent at uniformly heating the temperature, allowing the entire workpiece to be heated evenly.

[0046] Doors A1 and A2 that can be opened and closed horizontally are attached to the front of the drying furnace A, allowing the workpiece W to be carried in and out. Of course, a similar door may also be provided on the rear of the drying furnace A, in which case the workpiece W can be carried in and out from both the front and rear.

[0047] A hanging bracket 50 for hanging the workpiece W is installed at the center of the upper part of the drying chamber 11, and an appropriate detachable hook 51 is attached to the hanging bracket 50. The workpiece W is stored in the drying furnace A by hanging it on the hook 51.

[0048] (1) Change example 1 In the first embodiment described above, the workpiece W is suspended by the hanging fitting 50 and the hook 51 attached inside the drying chamber 11, but it is also possible to provide a platform on which the workpiece W is placed without providing such a hanging fitting 50. This configuration eliminates the need to hang the workpiece W on the hook 51, improving workability.

[0049] (2) Change example 2 The hanging fitting 50 in the first embodiment may be configured to be horizontally movable in the length direction of the heat source 20.

[0050] For this horizontal movement, a suspending fixture for suspending the workpiece may be attached to the conveying rail, and the workpiece together with the suspending fixture may be moved along the conveying rail by receiving power from a driving device.

[0051] With the above configuration, the work W suspended by the hanging fittings 50 from the aforementioned openable and closable doors A1, A2 can be transported out of the drying furnace A by moving it horizontally together with the hanging fittings 50 after drying is complete, and it is also possible to transport undried work W into the drying furnace A.

[0052] In this case, the undried work W is kept waiting outside the drying furnace A, and once the drying of the preceding work W is completed, the dried work W is transported out of the drying furnace A and at the same time the undried work W is transported into the drying furnace A, which makes it possible to work continuously and improves work efficiency.

[0053] (3) Change example 3 Instead of the system in the above-mentioned modified example 2 in which the workpiece receives power from the drive unit and moves along the conveying rail together with the hanging hardware, it is also possible to provide a platform on which the workpiece W is placed, as in the above-mentioned modified example 1, and configure the workpiece W together with the platform to receive power from the drive unit and move horizontally along the conveying rail.

[0054] (4) Other Although one embodiment of the present invention has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0055] A... Drying furnace, A1... Openable door, A2... Openable door, B... Insulated wall, B1... Insulated side wall, B2... Upper insulating top plate, B3... Lower insulating bottom plate, B4... Explosion vent, W... Workpiece, 10... Furnace body, 11... Drying chamber, 20... Heat source, 20a... Heat source, 20b... Heat source, 22... Heat source moving part, 22a... Heat source moving roller, 22b... Heat source moving rail, 23... Reflector, 24... Support part, 30... Duct, 31... Upper duct, 32... Side duct, 33... Lower duct, 33a... Injection nozzle, 40... Fan, 41... Motor, 50... Hanging bracket, 51... Hook

Claims

1. In a drying oven for drying workpieces, a furnace body having a drying chamber covered with a heat-insulating wall; a heat source that radiates infrared rays into the drying chamber; a duct provided in the drying chamber for sending air from an upper portion of the drying chamber to a lower portion of the drying chamber; a fan that sucks in air from the upper part of the drying chamber, blows the air into the duct, and sprays it into the lower part of the drying chamber; Equipped with The upper end of the heat source is lower than half the height of the drying chamber, The plurality of heat sources are provided opposite to each other inside the drying chamber, A drying furnace comprising a heat source moving unit that changes the distance between the opposing heat sources.

2. In a drying oven for drying workpieces, a furnace body having a drying chamber covered with a heat-insulating wall; a heat source that radiates infrared rays into the drying chamber; a duct provided in the drying chamber for sending air from an upper portion of the drying chamber to a lower portion of the drying chamber; a fan that sucks in air from the upper part of the drying chamber, blows the air into the duct, and sprays it into the lower part of the drying chamber; Equipped with The upper end of the heat source is lower than half the height of the drying chamber, The drying furnace, wherein the surface of the duct facing the drying chamber forms a reflective surface that reflects the infrared rays.

3. 3. The drying furnace according to claim 1, further comprising a duct forming member provided on the drying chamber side of the insulating wall to form the duct between the insulating wall and the duct forming member, the duct forming member being made of a metal material.

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