JPH0694018B2 - drying furnace - Google Patents

Description

TECHNICAL FIELD The present invention relates to a drying oven, and more particularly to a drying oven suitable for a drying oven utilizing near infrared rays.

(Prior Art) Conventionally, as a drying oven for drying an object to be dried or the like coated with various paints, a so-called hot air oven or a drying oven utilizing far infrared rays is known. The drying mechanism of these drying paths is understood as follows.

That is, first, the material to be dried, whose surface is coated with a solid coating material composed of a solvent and a resin such as an acrylic resin, is carried into the furnace. Next, hot air is blown or far infrared rays are irradiated. Then, the solvent on the surface of the coating applied to the material 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 side, the coating film solidifies due to overheating. Then, the solvent inside the surface penetrates the already solidified coating film surface and evaporates. Then, the trace of foaming remains on the surface and pinholes occur. Therefore, in the conventional hot air oven or the drying oven using far infrared rays,
Far infrared rays are radiated and hot air is blown so as to maintain a low temperature at which the solvent on the surface of the coating film does not foam and solidify immediately without rapid heating.

However, these conventional drying ovens have a problem that it takes time to dry because they are dried while maintaining a low temperature at which foaming does not occur. Further, far infrared rays and mid-infrared rays have a problem that the plastic coating film is difficult to penetrate and in the case of an object to be dried having a complicated shape, the shadow portion which is inevitably dried cannot be completely dried.

Therefore, a drying furnace utilizing 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" (Actual Kaihei 1-151873), "Paint baking furnace dedicated light board"
(Actual development 2-43217), USP 4,863,375 "BAKING METHOD F
`` OR USE WITH LIQUID OR POWDER VARNISHING FURNACE ''
(Baking method for youth with liquid or powder varnishing furnish). In these conventional examples, a drying furnace using near infrared rays, or a drying method in which a high temperature portion and a low temperature portion are sequentially formed and dried in the drying furnace, or a ceramic reflection plate is provided behind the near infrared lamp, There is also a statement that a heater is provided in the ceramic reflector.

On the other hand, as a conventional drying oven, a hot air drying oven (101) as shown in FIG. 9 is known. The hot air drying oven is located in the middle, and is located upstream of the effective part (101) b for heating the dried object (102) with hot air, and becomes higher toward the downstream side. The introduction section (101) a has an inclination, and the exclusion section (101) c is located on the downstream side of the effective section (101) b and becomes lower toward the downstream side. (103)
Is a conveyor that conveys the material to be dried (102) according to the in-furnace route. In this conventional hot air drying oven (101), the introduction part (101) a, the exclusion part (101) c, and the effective part (101).
The bottom surface A of the joint portion of b is set higher than the ceiling surfaces of the opening ends of the introduction portion (101) a and the exclusion portion (101) c. The purpose of making the point A higher than the point B is to avoid the divergence of excess heat and to avoid lowering the heat by mixing the outside air into the effective part (101) b heated by hot air.

(Problems to be Solved by the Invention) By the way, in the drying oven using near infrared rays, the baking time is shortened by about 1/10 to 1/3 as compared with the conventional hot air drying oven, and the drying efficiency is increased. ) B is shorter than the conventional hot air drying oven (101). However, if only the effective part (101) b of the conventional mountain furnace is shortened, the introduction part (101) a and the expulsion part (101) c become relatively long, and their existence affects the heating efficiency. Become.

(Means for Solving the Problem) The present invention is directed to an introduction portion 14 provided with an inclination that becomes higher toward the downstream side.
And an effective section 15 that is installed horizontally on the downstream side of the introduction section 14,
An unloading section 16 provided on the downstream side of the effective section 15 and provided with an inclination that becomes lower toward the downstream side, between the introducing section 14 and the effective section 15 and between the effective section 15 and the unloading section 16 and upward from the bottom surface of the furnace. A drying furnace characterized by comprising a bottom side shield plate 51 installed facing toward the drying furnace, and an introducing section 14 provided with an inclination that becomes higher toward the downstream side.
And an effective section 15 that is installed horizontally on the downstream side of the introduction section 14,
A carry-out section 16 installed on the downstream side of the effective section 15 and provided with an inclination that becomes lower toward the downstream side, a conveyor 17 installed on the furnace ceiling from the upstream side to the downstream side, and a hanger conveyed to the conveyor 17. Except for the passage part which is the passage point, at least the ceiling side shield plate 52 installed from the furnace ceiling of the introduction part 14 or the unloading part 16 toward the bottom side, and the air for discharging air from the passage part 54 toward the bottom side. A drying furnace characterized by comprising a curtain 55, and an introduction part 14 provided with an inclination that becomes higher toward the downstream side.
And an effective section 15 that is installed horizontally on the downstream side of the introduction section 14,
An unloading section 16 provided on the downstream side of the effective section 15 and provided with an inclination that becomes lower toward the downstream side, between the introducing section 14 and the effective section 15 and between the effective section 15 and the unloading section 16 and upward from the bottom surface of the furnace. The bottom side shielding plate 51 installed towards, the conveyor 17 installed from the upstream side to the downstream side in the furnace ceiling, and at least the introduction section 14 or except the passage section 54 which is a hanger passage point conveyed to the conveyor 17. A ceiling-side shielding plate 52 installed from the furnace ceiling of the carry-out section 16 toward the bottom side, and a drying furnace comprising an air curtain 55 that discharges air from the passing section 54 toward the bottom side, I will provide a.

(Function) Prevents the entry of outside air from the bottom side by using a drying furnace that consists of a bottom side shield plate installed between the introduction section and the effective section and between the effective section and the unloading section, facing upward from the bottom surface of the furnace. To do.

Except for the passing part, which is the hanger passing point conveyed to the conveyor, at least the ceiling side shield plate installed from the furnace ceiling of the introduction part or the unloading part to the bottom side, and the air is discharged from the passing part to the bottom side. The use of a drying furnace consisting of an air curtain prevents the entry of outside air from the ceiling surface.

At least the introduction part or unloading except for the bottom side shielding plate installed upward from the bottom surface in the furnace between the introduction part and the effective part and the effective part and the unloading part, and the passage part which is the hanger passage point conveyed to the conveyor. When the drying furnace is composed of a ceiling side shield plate installed from the ceiling inside the furnace to the bottom side, and an air curtain that discharges air from the passage part to the bottom side, the outside air from the bottom side of the ceiling surface is mixed. To prevent the introduction section unloading section from
Even if each is shortened, it prevents the entry of outside air.

(Embodiment) FIG. 1 showing a front center sectional view of an embodiment of the present invention,
Fig. 2 showing the same plan view, Fig. 1 Fig. 3a showing the XX section, Fig. 3b showing the YY cross section, Fig. 4 showing the perspective view around the lamp, and Fig. 5 showing the same plan view. ,
A description will be given according to FIG. 6 showing a cross-sectional view of a near-infrared lamp and FIG. 7 showing a cross-sectional view of another near-infrared lamp.

(11) is a drying oven. The drying oven (11) has a carry-in port (1
2) It is made of a metal hollow prism having an opening for the carry-out port (13). (14) is an introduction section, (15) is an effective section, and (16) is an unloading section. The carry-in port (12) and the carry-out port (13) are effective parts (1
It is installed lower than 5), and the introduction part (14) and the carry-out part (16) are 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 high reflection efficiency.
Mirror finishing may be performed. (17) is a conveyor. The conveyor (17) is installed so that it can be transported inside and outside the drying furnace (11). (18) is an article to be dried which is locked on the conveyor (17). The material to be dried (18) is, for example,
A 1-mm iron plate is coated with 30 μ of solvent and paint made of resin such as acrylic resin.

(51) is a bottom side shield plate. Bottom side shield (51)
Is the introduction part (14) as shown in FIGS. 1 and 3a.
It is installed between the effective part (15) and the effective part (15) from the bottom surface to the ceiling surface to a position lower than the bottom surface of the material (18) to be dried. It is desirable that the upper end of the bottom shielding plate (51) be installed as close to the bottom surface of the article to be dried (18) as possible because the heat exchange with the outside air is small. As the bottom side shield plate (51), the bottom side shield plate (51) having a different height may be selected and installed depending on the size of the article to be dried (18) to be conveyed. That is, for example, a plurality of bottom side shield plates (51) having different heights are prepared, and a slide is provided at the bottom side shield plate (51) installation location of the drying furnace (11) so that the material to be dried (18) to be conveyed is Select the type and install the bottom side shield plate (51) by fitting it to the slide. (52) is a ceiling side shielding plate. The ceiling side shield plate (52) passes through the hanger (53) that is hung on the conveyor (17) installed on the ceiling and that locks the material to be dried (18) at the tip so that it does not interfere with the passage of the hanger (53). The part (54) is provided and installed below the ceiling. (55) is an air curtain. The air curtain (55) has an air outlet (56)
Is installed on the ceiling of the drying furnace (11) across the width of the passage portion (54). The air in the air curtain (55) is supplied by an air pump (not shown). The upper end P of the bottom shield plate (51) and the lower end Q of the ceiling shield plate (52)
And are overlapped in a front view as shown in FIG.

(21) is a near infrared irradiation device. Two near infrared irradiation devices (21) are installed in this embodiment, but three or more near infrared irradiation devices (21) may be installed at equal intervals. Near-infrared irradiation device (21),
It has a near-infrared lamp (22), a lamp bank (23), and a reflector (24). The infrared rays emitted from the near infrared lamp (22) are 1-1,8μ, preferably 1-1,5μ.
Near-infrared light having a peak at is effective. The nine near-infrared lamps (22) are installed vertically, but the number is not limited. The near-infrared lamp (22) may have a circular cross section as shown in FIG. 6 or a parabolic curved surface as shown in FIG.
Install a reflector (26) on the back of 5). The lamp bank (23) has a near-infrared lamp (22) fixed on the front surface, and the surface on the near-infrared lamp (22) side is made of a metal having a mirror surface treatment or a metal having a high reflection efficiency. The reflection plate (24) has a mirror-finished surface, but may be made of a metal having good reflection efficiency, and is made of a plate-like body having a curved tip. The reflection plate (24) may further have a flat plate shape that is not curved.
(27) is the reflector rotation axis. Reflector rotation axis (27)
As shown in FIG. 4, the lamp banks (23) are vertically mounted on the lamp banks (23) side of the two reflectors (24) as shown in FIG. 4, but as shown in FIG. , The reflectors (24), (24) are integrally formed, and the lamp bank (2
3) You may install one on the back of the part. In the embodiment shown in FIG. 5, the reflection plate (24) is rotated about the rotation axis (27) of the reflection plate to set the light collecting direction in advance.

(41) is a heater. The heater (41) is an electric heater and is installed on the back surface of the reflection plate (24). Heater (4
In 1), the reflector (24) is heated to maintain the surface of the reflector (24) at a temperature higher than the ambient temperature of the drying furnace (11). It suffices that the temperature of the reflecting surface is higher than the temperature of the atmosphere of the drying furnace (11) in the range of 3 to 5 ° C., and the heating temperature of 5 ° C. or higher is not necessarily required.

Next, the operation of the embodiment will be described. Items to be dried (18)
Is coated with a solvent and a resin such as acrylic resin in the previous step, and is locked to the conveyor (17). The conveyor (17) is driven by the conveyor drive motor (34). The material to be dried (18) is conveyed to the conveyor (17), enters the drying furnace (11) through the carry-in port (12), and reaches the effective section (15). The light collecting direction is determined by the position of the reflecting plate (24) set in advance, and the energy density increases in the light collecting direction, so that the object surface temperature of the object to be dried (18) rises and becomes higher. Therefore, it is possible to increase the temperature difference between the high temperature part and the low temperature part in the furnace, as compared with the case without the reflector.

When the near-infrared rays are irradiated to the material to be dried, most of the near-infrared rays penetrate the coating film, are absorbed at the position of 1 to 2 nm from the surface of the metal plate, the temperature of the metal surface rises, and the coating film is heated from inside. Then, the curing starts near the metal surface. Therefore, rapid heating is performed before the fluidity of the coating film surface is reduced, the solvent is blown away, and solvent bubbling and pinholes are not generated after the fluidity of the coating film surface is lost. Therefore, curing can be performed in a short time, and the drying furnace itself can be downsized.

The heater (41) heats the reflection plate (24) and maintains the surface of the reflection plate (24) at a temperature higher than the ambient temperature of the drying furnace (11). For heating, the temperature of the reflecting surface is 3 to 5 ° C from the atmosphere of the drying oven (11)
By keeping it high, the surface of the reflection plate (25) is maintained above the dew point of the solvent gas, so that tar components in the solvent are prevented from sticking to the reflection surface and the reflection surface of the reflection plate (24) is prevented. It is possible to avoid a decrease in reflection efficiency.

As shown in FIGS. 3a and 3b, the drying oven (11)
Inside, a bottom side shield plate (51), a ceiling side shield plate (52), and an air curtain (55) are installed. The air curtain (55) is
It is installed on the ceiling of the drying furnace (11) across the width of the passage portion (54) with the air jet port (56) facing downward, and is installed between the upper end P of the bottom side shield plate (51) and the ceiling side shield plate (52). As shown in FIG. 1, the lower end Q has an overlapping shape in a front view. Therefore, the effective part (15) is cut off from the introduction part (14) and the carry-out part (16), and no external air is mixed into the effective part (15). Avoided, effective part (1
The surplus heat in 5) does not dissipate. Therefore, it is possible to omit the lengths of the E and F portions in the introduction section (14) and the carry-out section (16).

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

Effective part (15) 5,000mm Effective part transit time 10 minutes Near infrared irradiation device 2 units Near infrared irradiation device interval 2,800mm Distance from end of effective part to near infrared irradiation device center 1,600m
m Iron plate thickness (bonded steel plate) 2 mm Atmosphere temperature 160 ° C Fig. 8 shows a with and without a reflector. Reference numeral c is a reflector mounting portion, I is an introduction portion, and II is an effective portion.

When the reflector is attached, the energy density of infrared rays is concentrated in front of the lamp, and the energy density at the furnace edge is small, so the initial temperature is higher when the reflector is not installed than when the reflector is attached. However, the ascending point is slow,
The surface temperature reverses at a point of about 4 minutes from the effective part entrance. In the vicinity of the lamp bank, the temperature rise gradient becomes larger with the reflection plate, intersects with the temperature curve without the reflection plate in front of the lamp bank, and thereafter the surface temperature with the reflection plate becomes higher. This indicates that the material to be dried is rapidly irradiated with the temperature in front of the lamp and the temperature rises rapidly, the temperature of the coating film rises rapidly, the crosslinking reaction of the resin is promoted as the evaporation of the solvent progresses, and the degree of crosslinking increases. It is possible to increase.

(Effect of the Invention) Therefore, according to the present invention, it is possible to prevent the outside air from being mixed into the effective portion in the drying furnace.

[Brief description of drawings]

FIG. 1 is a front center sectional view of an embodiment of the present invention, FIG. 2 is a plan view of the same, FIG. 3a is a sectional view of FIG. 1 XX, and FIG.
YY cross-section, Fig. 4 is a perspective view around the lamp, Fig. 5 is a plan view of the same, Fig. 6 is a cross-sectional view of a near-infrared lamp, Fig. 7 is a cross-sectional view of another near-infrared lamp, and Fig. 8 is FIG. 9 is a temperature change diagram of the example, and FIG. 9 is a conventional example diagram. (11) …… drying oven, (14) …… introduction section, (15) …… effective section, (16) …… delivery section, (17) …… conveyor, (51)…
… Bottom side shield, (52) …… Ceiling side shield, (53) ……
Hanger, (54) …… Passing part, (55) …… Air curtain

Claims (3)

[Claims] 1. An introduction part 14 provided with an inclination that becomes higher toward the downstream side, an effective part 15 installed horizontally on the downstream side of the introduction part 14, and a downstream side installed on the downstream side of the effective part 15. And a bottom surface side shield plate 51 installed upward from the bottom surface of the furnace between the introduction portion 14 and the effective portion 15 and between the effective portion 15 and the discharge portion 16 and an inclined portion. A drying oven characterized by comprising. 2. An introduction section 14 provided with an inclination that becomes higher toward the downstream side, an effective section 15 installed horizontally on the downstream side of the introduction section 14, and a downstream side installed on the downstream side of the effective section 15. The unloading section 16 provided with an inclination that becomes lower as it goes to, the conveyor 17 installed from the upstream side to the downstream side in the furnace ceiling, and the conveyor 17
Except for the passing portion 54 which is a hanger passing point conveyed to the ceiling side shielding plate 52 which is installed at least from the furnace ceiling of the introducing portion 14 or the unloading portion 16 toward the bottom surface side, and from the passing portion 54 toward the bottom surface side. A drying furnace characterized by comprising an air curtain 55 that discharges air. 3. An introduction part 14 provided with an inclination that becomes higher toward the downstream side, an effective part 15 horizontally installed on the downstream side of the introduction part 14, and a downstream side installed on the downstream side of the effective part 15. And a bottom surface side shield plate 51 installed upward from the bottom surface of the furnace between the introduction portion 14 and the effective portion 15 and between the effective portion 15 and the discharge portion 16 and an inclined portion. , The conveyor 17 installed from the upstream side to the downstream side on the furnace ceiling, and the conveyor 17
Except for the passing portion 54 which is a hanger passing point conveyed to the ceiling side shielding plate 52 which is installed at least from the furnace ceiling of the introducing portion 14 or the unloading portion 16 toward the bottom surface side, and from the passing portion 54 toward the bottom surface side. A drying furnace characterized by comprising an air curtain 55 that discharges air.