JPH0356108B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light irradiation method, and more particularly to a light irradiation method that can efficiently irradiate a long object having a circular cross section.

As a means of drying paint applied to objects to be painted,
Traditionally, drying has been carried out in a heating furnace consisting of a heater, etc., but recently, in order to speed up the drying process, a photocurable paint is applied to the object to be irradiated, and the coated film is irradiated with light. It is then dried and cured. When the object to be irradiated is long and has a circular cross section, for example when drying and curing a rust-preventing coating applied to the surface of a metal pipe, many lamps are used to form a cylindrical shape. The light beams are arranged in an annular or annular shape, and are processed while passing through the light irradiation section formed thereby. This drying and curing process is one of a series of processes, and the object to be irradiated is carried in by a conveyor from the previous process, processed continuously, and carried out to the subsequent process, so the level of the pass line of the irradiated object is constant. It is. On the other hand, the position of the lamp within the light irradiation furnace is also fixed. Therefore, if the object to be irradiated has a constant outer diameter, uniform treatment can be achieved by positioning the lamp so that the object passes through the center of the object, but in reality there are various of outer diameter is dried and hardened. FIG. 6 is an explanation of this conventional example, and is a schematic diagram showing a plane perpendicular to the axis. Here, L is the inscribed circle of the lamps arranged in a cylindrical shape, and the irradiated object W is transported on the path line P, but since the levels of L and P are each constant, the irradiated object W If the outer diameters of L and W are different, the centers of L and W will be eccentric. Therefore, the distance from L to W becomes uneven, and depending on the surface of the object to be irradiated, some parts are irradiated more strongly than necessary, while other parts are insufficiently irradiated and dry poorly. Therefore, in order to eliminate this problem even a little, the illuminance within the light irradiation area should be made as uniform as possible by changing the angle of the mirror little by little and emitting light in each direction instead of concentrating the irradiated light from each lamp in the center. Attempts have been made to do so, but these also have limitations and have not produced sufficient results. Furthermore, with this method,
By lighting all the lamps, the illuminance within the light irradiation area is made uniform, so even when the object is small in diameter and has a small surface area and requires a small amount of irradiation, all the lamps are turned on. , it was extremely uneconomical.

The present invention has been made in view of these circumstances, and it is an object of the present invention to provide a light irradiation method that can uniformly and efficiently irradiate the surface of a long object to be irradiated with various outer diameters. . The purpose of this is to arrange a plurality of sets of lamps and mirrors inside the furnace in an annular or cylindrical shape facing inward, and to transport the lamps and mirrors on a pass line at a certain level into the light irradiation section formed by this. This is a light irradiation method in which the lamps are passed through a long light irradiation part and irradiated with the light, and these lamps are driven by a power source that can be turned on completely or separately, and the lamps and mirrors are lit separately. The assembly is movable in the radial direction, and during irradiation, the axis of the irradiated object and the light irradiation section are aligned by moving the furnace body up and down according to the outer diameter of the irradiated object, and the When the outer diameter of the object is small, this can be achieved by a light irradiation method characterized by increasing the lighting interval by lighting at a distance and bringing the lighted lamp and mirror combination close to the object to be irradiated.

Embodiments of the present invention will be specifically described below based on the drawings.

1 and 2 show a light irradiation furnace used in an embodiment of the present invention.
A is opened, and an object W to be irradiated, which is a metal pipe whose surface is coated with a photocurable paint, is conveyed by a roller conveyor 2 and passes through both round holes 1a, 1a. The level of this roller conveyor 2 is constant, and therefore the level of the pass line P of the object W to be irradiated is constant. A drive stand 3 with a built-in motor is arranged below the equipment box 1, and above it a cylindrical furnace body 4 is supported by a feed screw rod 31, and the furnace body 4 is moved vertically within a predetermined range. Screw feeding is possible. Inside the furnace body 4, as shown in FIG. 3, a large number of sets of lamps 5 and mirrors 6 are arranged facing inward. In this embodiment, the lamp 5 is a straight tube type with an output of 16 KW and a light emitting length of 1 m, and is arranged in a cylindrical shape with a diameter of 500 mm, thereby forming a light irradiation section 7. Of course, the lamp 5 may be a spherical point light source, in which case it is arranged in an annular shape. And each mirror 6 is
Although the irradiation light is a substantially parallel beam and is arranged so as to be focused on the axis C of the light irradiation section 7, it is not necessarily necessary to focus the light on the axis C. In short, the light irradiation section 7 is The irradiation should be done uniformly.

Next, as shown in FIG. 4, each lamp 5 is made up of two adjacent lamps forming a set, and each set, . . . is connected to the power supply in parallel.
The lamps 5a and 5b are arranged in the order of 5a and 5b, allowing for separate lighting in which the lamp 5a is turned off and only the lamp 5b is turned on. As shown in FIG. 4B, the combination of the lamp 5b and its mirror 6, which are lit at a distance, is movable toward the axis C. Of course, the method of distant lighting is not limited to this, but when the range of the outer diameter of the object W to be irradiated is large and the object W to be irradiated has a small diameter even though there are many lamps 5 arranged, A set of four lamps 5 is arranged in the order of 5a, 5b, 5a, and 5c. First, the lamp 5a is turned off, then the lamps 5b and 5c are turned on at equal intervals, and then the lamp 5b is also turned off. The second stage of separate lighting may be performed, and if necessary, multi-stage separate lighting such as third and fourth stages may be performed, and the set of lamp 5 and mirror 6 to be lit accordingly. Advance.

Although not shown, a blower and an exhaust device are connected to the light irradiation furnace to cool the lamp 5. A shutter or the like is attached to the round hole 1a to prevent the light from the lamp 5 from leaking to the outside.

Next, a method of irradiation using the light irradiation furnace configured as described above will be explained. The object W to be irradiated, which is a metal pipe coated with a photocurable paint, is conveyed from the previous process by the roller conveyor 2 and passes through the light irradiation section 7. The diameter is determined by measurement or other means. Since the pass line P is at a constant level, the level of the axis changes as the outer diameter of the object W changes, as shown in FIG. Moved up and down. That is, when the outer diameter is small, the level of the axial center is low, so the furnace body 4 descends, and conversely, when the outer diameter is large, it rises and aligns with the axial center of the irradiated object W, regardless of the difference in outer diameter. The axis C of the light irradiation unit 7 coincides with the axis C. Therefore, since the distance from each lamp 5 to the surface of the object W to be irradiated is always constant, uneven irradiation depending on the part does not occur.

By the way, if the outer diameter of the object W to be irradiated differs, its surface area will also differ, and the total amount of irradiation required for drying and curing will also differ. That is, when the outer diameter is large, the total amount of irradiation required is large, so all of the lamps 5 are turned on as shown in FIG. 4A. On the other hand, as the outer diameter becomes smaller, the required amount decreases, so as shown in Fig. 4B
Only the lamp 5b is lit as shown in FIG.
This combination of lamp 5b and mirror 6 moves in the direction of axis C and approaches the surface of object W to be irradiated. Therefore,
Even if the outer diameter of the object W to be irradiated changes, it is possible to always achieve the same hardening as when irradiating with the axis aligned in the furnace body 4 that is suitable for the outer diameter, resulting in uniform curing with optimal power consumption. It becomes possible to irradiate the

In this way, the present invention aligns the axes of the irradiated object and the light irradiation part by moving the furnace body up and down according to the outer diameter of the irradiated object, and when the outer diameter of the irradiated object is small, In this method, the lighting interval is increased by lighting at a distance, and the set of lit lamps and mirrors is brought closer to the object to be irradiated, so the surface of the object to be irradiated is uniformly irradiated regardless of the difference in its outer diameter, and there is no need to It can be dried and cured satisfactorily without forming areas that are strongly irradiated or areas that are insufficiently irradiated and thus fail to cure. When the outer diameter is small, power is not wasted by lighting up needlessly, and excessive irradiation is not caused. Therefore, according to the present invention, it is possible to provide a light irradiation method that can uniformly and efficiently irradiate the surface of a long object to be irradiated with different outer diameters.

[Brief explanation of drawings]

Fig. 1 is a side view of the device used in the embodiment of the present invention, Fig. 2 is a front cross-sectional view, Fig. 3 is a schematic explanatory diagram of the mirror and lamp, and Fig. 4 A and B are of the remote lighting. FIG. 5 is an explanatory diagram of the level of the irradiated object and the lamp, and FIG. 6 is an explanatory diagram of the level of the irradiated object and the lamp in a conventional example. 1...Equipment box, 2...Roller conveyor, 3
... Drive stand, 31 ... Feed screw rod, 4 ... Furnace body,
5...Lamp, 6...Mirror, 7...Light irradiation part,
W...Object to be irradiated, P...Pass line, L...Inscribed circle of lamp group, C...Axis center.

Claims (1)

[Claims] 1 A plurality of sets of lamps and mirrors are arranged inwardly in a circular or cylindrical shape within the furnace body, and a long lamp is conveyed on a pass line at a certain level inside the light irradiation section formed by this. This is a light irradiation method that passes through the object to be irradiated and irradiates it, and these lamps are driven by a power source that can be turned on at all times and at intervals, and the combination of lamps and mirrors that are lit at intervals is further reduced in diameter. During irradiation, by moving the furnace body up and down according to the outer diameter of the irradiated object, the axes of the irradiated object and the light irradiated object are aligned, and the outer diameter of the irradiated object is adjusted. is small, the light irradiation method is characterized by increasing the lighting interval by lighting at a distance and bringing the set of the lamp and mirror to be lit closer to the object to be irradiated.