JPH04114764A - Near infrared ray emission device - Google Patents

Abstract

PURPOSE:To carry out drying process in which the difference between a high temperature section and a low temperature is clear by installing reflection plates on both sides of a near infrared ray lamp set facing the inner section direction of the drying oven and also in the direction in which the irradiation density of near infrared rays to be emitted gets higher. CONSTITUTION:A near infrared ray lamp 22 is set facing the inner section direction of a drying oven 11. Reflection plates 24 and the drying oven are installed on both sides of the near infrared ray lamp 22 and also in the direction in which the emission density of near infrared rays to be emitted gets higher. As a result, the drying process in which the difference between a high temperature section and a low temperature section is clear can be carried out to improve the efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a near-infrared irradiation device, and more particularly to a near-infrared irradiation device provided with a reflector for a drying oven that utilizes near-infrared rays.

(Prior Art) Conventionally, so-called hot air ovens and drying ovens using far infrared rays are known as drying ovens for drying objects coated with various paints. The drying mechanism of these drying paths is understood as follows.

That is, first, the object to be dried, whose surface has been coated with a paint consisting of a solid component made of a solvent and a resin such as acrylic resin, is carried into a furnace. Next, hot air is blown or far infrared rays are irradiated. Then, the solvent on the surface of the paint applied to the object to be dried is first evaporated, and the surface loses fluidity and solidifies. When heat such as hot air propagates inside, that is, toward the base material, the coating film solidifies due to overheating. Then, the solvent inside the surface breaks through the already solidified coating surface and evaporates. This leaves traces of foaming on the surface and creates pinholes. For this reason, conventional hot air ovens or drying ovens that use far infrared rays irradiate far infrared rays and blow hot air to maintain a low temperature that does not cause the solvent on the coating surface to foam and solidify immediately without heating up rapidly. Let's do it.

However, these conventional drying ovens have a problem in that drying takes a long time because the drying is performed while maintaining a low temperature that does not cause foaming. Further, far infrared rays and mid-infrared rays do not easily pass through plastic coatings, and there is also the problem that shadow areas, which inevitably occur in the case of objects to be dried having complex shapes, cannot be completely dried.

Therefore, a drying oven using near infrared rays has been proposed as a means for shortening the drying time of the material to be dried. For example, "Near-infrared liquid, powder, coating, stove" (Utility Model Application Publication No. 1-151873), [Tip Plate J for Paint Baking Furnace (Utility Model Application Publication No. 2-43217), [l5P4,86
3,375 r BAKING NET) IOD FO
RUSE WITHLIQUID ORPOWDERV
ARNISHING FURNACE” (baking)
Method for Use with Liquid or Powder Varnishing Furnace), etc. These conventional examples include a drying oven that uses near-infrared rays, a drying method that sequentially forms a high-temperature section and a low-temperature section in the drying oven, or a method in which a ceramic reflector is installed behind the near-infrared lamp. There is also a statement that a heater is installed in the ceramic reflector.

(Problems to be Solved by the Invention) However, there has been a demand for further improvement in the efficiency of drying ovens that utilize near-infrared rays.

(Means for Solving the Problems) The present invention includes a near-infrared lamp installed toward the inside of the drying oven;
To provide a near-infrared irradiation device characterized by comprising reflector plates for a drying oven provided on both sides of a near-infrared lamp and in a direction where the irradiation density of near-infrared rays to be irradiated becomes high.

(Function) A near-infrared irradiation device is installed with a reflector plate for the drying oven installed on both sides of the near-infrared lamp installed toward the inside of the drying oven and in a direction where the irradiation density of near-infrared rays is high. By installing multiple units side by side with openings,
It is possible to increase the difference between the high-temperature part and the low-temperature part between the near-infrared irradiation devices.

(Embodiment) FIG. 1 shows a front center sectional view of an embodiment of this invention.
Fig. 2 shows the same plan view, Fig. 3 shows the perspective view around the lamp, Fig. 4 shows the same plan view, Fig. 5 shows the same plan view of other embodiments, near-infrared lamp A cross-sectional view of the near-infrared lamp is shown in FIG. 6, and a cross-sectional view of the near-infrared lamp in the same area is shown in FIG. 7.

(Ll) is a drying oven. The drying oven (11) is located at the loading entrance (
12), consists of a metal hollow prismatic shape with an opening (13). (14) is the introduction part, (15) is the effective part, (
16) is an unloading section. Loading entrance (12), loading exit (13)
) is set lower than the effective part (I5), the introduction part (14),
The unloading section (16) is installed at an angle. In this embodiment, the inner surface of the effective portion (15) is made of a metal plate having a surface with good reflection efficiency, but it may be mirror-finished. (17
) is a conveyor. The conveyor (17) is connected to the drying oven (1
1) Installed so that it can be transported both inside and outside. (18) is an object to be dried that is stopped by the conveyor (17). The material to be dried (18) is dried on a 1 mm iron plate, for example, by 3mm in the previous process.
A paint consisting of a μ solvent and a resin such as acrylic resin is applied.

(21) is a near-infrared irradiation device. Although two near-infrared irradiation devices (21) are installed in this embodiment, three or more near-infrared irradiation devices (21) may be installed at equal intervals. Near-infrared irradiation device (21)
are a near-infrared lamp (22), a lamp bank (23),
It has a reflecting plate (24). The infrared rays emitted by the near-infrared lamp (22) are 1 to 1.8 μ, preferably 1
Near-infrared light having a peak at ~1.5μ is effective. Nine near-infrared lamps (22) are installed horizontally, vertically, but the number is not limited. The cross section of the near-infrared lamp (22) may be circular as shown in FIG. 6 or parabolically curved as shown in FIG. Install a reflector (26). The lamp bank (23) has near-infrared lamps (
22) is fixed, and the surface on the near-infrared lamp (22) side is made of a mirror-treated metal or a metal with good reflection efficiency. The reflecting plate (24) may have a mirror-finished surface or may be made of metal with good reflection efficiency, and may be a plate-shaped body with a curved tip. The reflecting plate (24) may further have a flat plate shape that is not curved. (27) is the reflection plate rotation axis. Even if the reflector rotation shaft (27) is attached vertically to the lamp bank (23) side of the two reflectors (24) as illustrated in FIG. Lamp bank (23), reflector (24), (24)
) may be integrally formed and one piece may be installed on the back of the lamp bank (23) portion. (31) is the reflector rotation axis (27
) drive motor. The drive motor (31) rotates in forward and reverse directions to rotate the reflection plate rotation shaft (27) and move the tip of the reflection plate (24) toward the center or wall of the drying oven (11). (32) is a control device consisting of a microcomputer or the like, and controls the drive of the drive motor. (33) is a non-contact type sensor, which is installed upstream of the conveyor (17) of the near-infrared irradiation device (21) to sense the proximity of the material to be dried (18). (34) is a conveyor drive motor. Both the sensor (33) and the conveyor drive motor (34) are connected to the control device (32). The near-infrared irradiation device may be fixed.

In the embodiment illustrated in FIG.
) around the center of rotation to set the direction of condensing light in advance.

(41) is a heater. The heater (41) is an electric heater and is installed on the back surface of the reflector (24).

The heater (41) heats the reflector (24) and
4) Maintain the surface at a higher temperature than the ambient temperature of the drying oven (11). The heating may be performed as long as the temperature of the reflective surface is higher than the temperature of the atmosphere of the drying oven (11) within a range of 3 to 5°C, and the temperature is 5°C or less.
Higher temperatures are not necessarily required.

Next, the operation of the embodiment will be explained. Materials to be dried (18
) is coated with a paint consisting of a solvent and a resin such as acrylic resin in a previous step, and is secured to a conveyor (17). The conveyor (17) is driven by a conveyor drive motor (34). The material to be dried (18) is conveyed to the conveyor (17), enters the drying oven (11) through the inlet (12), and reaches the effective section (15). Then, in the embodiment shown in FIGS. 4 and 5, the proximity of the object to be dried (18) is sensed by the sensor (33).

When the sensor (33) senses, the signal is sent to the control device (32).
). The control device (32) includes a drive motor (3
1) to rotate each reflecting plate (25) toward the a side. The control device (32) is a conveyor drive motor (34)
The conveyor drive speed signal is also transmitted. The control device (32) controls the reflection plate (32) in synchronization with the drive speed of the conveyor based on the input conveyor drive speed signal.
25) in the direction b, that is, the direction of movement of the material to be dried (18),
Move according to the movement speed. Downstream sensor (3
3) As the detection is sequentially performed, the downstream near-infrared irradiation device (21) is sequentially activated in the same way. Material to be dried (1
8) is outside the irradiation range of the near-infrared irradiation device, for example, after a certain period of time has elapsed after detection by the sensor (33), the drive motor (31) is driven by the control device (32) and the reflector rotation shaft ( 27) to face the front again.

The reflection of the near-infrared lamp (22) by the reflector plate (25) is the near-infrared lamp (22) of the near-infrared lamp (22).
The energy density for the object to be dried (18) during the previous passage increases, and the surface temperature of the object to be dried (18) increases.

Furthermore, since the reflecting plate (25) moves in synchronization with the transport speed of the material to be dried (18), the irradiation time of the near-infrared lamp (22) is extended.

In the embodiment shown in FIG. 9, the temperature is higher in the light collection direction where the light collection direction is determined from the predetermined position of the reflection plate (24). Therefore, it is possible to increase the difference between high and low temperatures in the furnace compared to the case without a reflector.

When the material to be dried is irradiated with near-infrared rays, most of the near-infrared rays pass through the paint film and are absorbed at a position 1 to 2 nm from the surface of the metal plate, increasing the temperature of the metal surface and heating the paint film from within. Hardening begins near the metal surface. Therefore, rapid heating is performed before the fluidity of the coating surface decreases, and the solvent is blown away, so that no solvent foaming or pinholes occur after the coating surface loses fluidity. Therefore, curing can be performed in a short time, and the drying oven itself can be downsized.

The heater (41) heats the reflector (24) and
4) Maintain the surface at a higher temperature than the ambient temperature of the drying oven (11). The heating is performed by maintaining the temperature of the reflecting surface 3 to 5° C higher than the atmosphere of the drying oven (11), thereby maintaining the surface of the reflecting plate (25) above the dew point of the solvent gas.
It is possible to prevent tar and the like in the solvent from sticking to the reflecting surface, and it is possible to avoid a decrease in the reflection efficiency of the reflecting surface of the reflecting plate (24).

(Example 1) A drying oven having the shape shown in Figures 1 and 2 was used, the near-infrared irradiation device was fixed, and the temperature change on the surface of the dried object was measured depending on the presence or absence of a reflector. .

Effective part (15) 5,000mm
Effective section passage time: 10 minutes Near-infrared irradiation device 2 units Near-infrared irradiation device spacing 2,800 mm Distance from the end of the effective section to the center of the near-infrared irradiation device
1,600mm steel plate thickness (bonde steel plate)
2mm ambient temperature
Fig. 8 shows a case where a 160° C reflector is installed and a case where a 160° C reflector is not installed. C is the part where the reflector is attached, ■ is the introduction part, and ■ is the effective part.

When a reflector is attached, the energy density of infrared rays is concentrated in front of the lamp, and the energy density at the hearth end is reduced, so the initial temperature may be higher without a reflector than with a reflector. Regardless, the rising point is slow,
The surface temperature reverses at about 4 minutes from the effective part entrance.

Near the lamp bank, the temperature rise gradient becomes larger in the case with the reflector, intersects the temperature curve without the reflector at the front of the lamp bank, and thereafter the surface temperature in the case with the reflector becomes higher. This indicates that the material to be dried is rapidly irradiated in front of the lamp and its temperature rises, causing a rapid rise in the temperature of the coating film, promoting the crosslinking reaction of the resin as the solvent evaporates, and reducing the degree of crosslinking. It becomes possible to increase the number of people.

(Effects of the Invention) Therefore, according to the present invention, it is possible to provide an efficient drying oven that is capable of drying with a clear difference between a high temperature part and a low temperature part in near-infrared irradiation.

[Brief explanation of the drawing]

FIG. 1 is a front center sectional view of an embodiment of the invention, FIG. 2 is a plan view of the same, FIG. 3 is a perspective view of the area around the lamp, FIG. 4 is a plan view of the same, and FIG. 5 is another embodiment. 6 is a sectional view of the near-infrared lamp, FIG. 7 is a sectional view of the near-infrared lamp, FIG. 8 is a temperature change diagram of the example, and FIG. 9 is a further example of another example. FIG.

Claims (1)

[Claims] A near-infrared lamp installed toward the inside of the drying oven,
A near-infrared irradiation device characterized by comprising a drying oven reflector plate provided on both sides of a near-infrared lamp in a direction where the irradiation density of the near-infrared rays to be irradiated becomes higher.