JPH0459930A - Continuous irradiation method for high-energy beam - Google Patents

Abstract

PURPOSE:To continuously and uniformly irradiate a traveling strip with an electron beam in the crosswise direction of the strip by concaving the cross section of the strip orthogonal to the traveling direction toward the irradiation source side in conformity to a curve of the second order. CONSTITUTION:The traveling strip 1 is scanned by a fixed electron gun 2 in the direction crossing the traveling direction to irradiate the strip 1 with an electron beam 3. Since the strip 1 is moved, the scanning direction of the electron gun 2 is inclined in the direction orthogonal to the strip traveling direction. In this case, the cross section of the strip in the direction orthogonal to the strip 1 traveling direction is concaved in conformity to a curve of the second order, and beam irradiation is carried out. Consequently, even the traveling strip 1 is uniformly irradiated with the beam in its crosswise direction.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is directed to a high-energy beam such as a laser beam or an electron beam while conveying a strip of metal, plastic, or various composite materials. It relates to a method of repeatedly scanning and continuously irradiating the surface of a strip with a high-energy beam.

(Prior Art) High-energy beam irradiation is widely used for the purpose of surface modification of the various strips mentioned above.

For example, Japanese Patent Application Laid-open No. 58-181820 discloses that a touch roll is used to support the strip from the back side, flatten it, and then irradiate it with a laser beam.
-23823 and No. 63-83227 each disclose a method of irradiating laser beams by arranging multiple irradiation devices,
JP-A-56-112419 discloses that a bundle of optical fibers is lined up in the width direction of a strip and irradiated with a laser beam.

In addition, Japanese Patent Laid-Open No. 63-9621 discloses that the quality of steel sheets can be improved by irradiating an electron beam in a direction perpendicular to the rolling direction of the steel sheets.
This is disclosed in Japanese Patent Laid-Open No. 1-298118, and an apparatus in which the energy density does not change depending on the irradiation position during electron beam irradiation has been proposed in Japanese Patent Application Laid-Open No. 1-298118.

In other words, when an electron beam is scanned from a fixed irradiation source toward a flat strip, the beam spot, which is circular at the center of the scanning area, becomes elliptical toward the edge of the scanning area, so the energy density decreases toward the edge of the scanning area. becomes smaller.

Therefore, the above-mentioned publication proposed an apparatus having a function of curving a strip onto which an electron beam is irradiated so that it has an arcuate cross section.

(Problem to be solved by the invention) Is it possible to uniformly irradiate the strip with an electron beam in the width direction of the strip using the above-mentioned device? If continuous irradiation is carried out in a direction perpendicular to the direction of conveyance of the strip while the strip is being conveyed. Since the scanning direction of the electron beam must be tilted with respect to the direction perpendicular to the transport direction depending on the transport speed, the problem arises again that the energy density changes depending on the irradiation position.

An object of the present invention is to propose a method that can uniformly irradiate a strip in the width direction even when continuously irradiating the strip with an electron beam while it is being transported.

(Means for Solving the Problem) This invention scans a high-energy beam irradiation source fixedly arranged opposite to the strip conveyance path in a direction tilted toward the conveyance direction from a direction perpendicular to the strip conveyance direction. When irradiating the surface of the strip with the high-energy beam, the strip has a high-energy beam whose cross section in a direction perpendicular to the conveying direction is held in a concave shape that curves toward the irradiation source according to a quadratic curve. This is a continuous irradiation method.

Furthermore, when the conveyance speed of the strip changes, it is advantageous in practice to select a quadratic curve according to the conveyance speed.

Next, continuous irradiation with a high-energy beam according to the present invention will be explained with reference to FIG.

In the figure, reference numeral 1 denotes a strip being conveyed, and a high-energy beam irradiation source, that is, a fixedly arranged electron gun 2 in the illustrated example, is scanned across the strip 1 in a direction transverse to the conveying direction. Irradiate with electron beam 3. At this time, since the strip 1 is in motion, the electron gun 2 tilts its scanning direction toward the conveyance direction with respect to the direction perpendicular to the strip conveyance direction.

In beam irradiation with the scanning direction of the electron beam tilted in this way, as shown in FIG. 1(b), the strip 1
The beam irradiation is performed after giving the strip 1 a concave shape whose cross section in a direction perpendicular to the conveyance direction is curved according to a quadratic curve.

(Function) Now, when the beam irradiation source is fixedly arranged and the irradiation source is rotated to scan, the beam spot on the flat surface shown in Fig. It becomes an almost perfect circle at the position where the distance from the irradiation source is the minimum), and it becomes an ellipse at the scanning end section B (the position where the distance from the irradiation source is the maximum). Therefore, the energy density of the irradiated beam is highest at the A section, and decreases as it moves from the A section toward the B section at the scanning end.

To make the energy density of the beam uniform over the entire scanning length, that is, to make the beam spot circular over the entire scanning length, it is sufficient to arrange the irradiated surface on an arc whose radius is the distance between part A and the irradiation source. can be achieved by curving according to this arc.

By the way, in order to irradiate the strip being transported with an electron beam and to arrange the electron beam spots regularly in the width direction of the strip I as shown in FIG. 3(a), it is necessary to irradiate the strip as shown in FIG. , the conveying speed V of strip 1 is
, the beam scanning direction is tane=l/Vs (
It is necessary to tilt the strip 1 at an angle θ expressed by Vs (beam scanning speed) in the transport direction of the strip 1.

When the beam scanning direction is tilted toward the strip conveyance direction in this way, even if the strip is curved along an arc as described above, the spot cannot be made circular over the entire scanning length.

As mentioned above, when the direction is perpendicular to the beam scanning direction or the transport direction, it is preferable to curve the strip according to the arc of a circle determined by the distance between the strip and the irradiation source, and here the cylinder shown in FIG. Assuming that the end face is a circle, the above circular arc becomes BIB2. If a scanning beam passes through this cylinder with its end face tilted at an angle θ to the strip conveyance direction, the cross section perpendicular to the strip conveyance direction will pass through the plane M, and it will be cut at this plane M. The other side becomes an ellipse. Therefore, part of the arc B=84 of the ellipse corresponds to the arc BI32,
It can be seen that it is advantageous to curve the strip according to the arc of an ellipse if the beam scanning direction is tilted at an angle e with respect to the direction perpendicular to the transport direction.

In addition, whether the curvature of the strip follows the arc of an ellipse or not, the deformation of the ellipse during acceleration and deceleration of the strip conveyance speed, the deformation of the ellipse due to the strip catenary, or the correction of defective strip shapes should be taken into account when determining the strip. In order to achieve more uniform irradiation by finely adjusting the curved shape of the strip, in this invention we decided to curve the strip according to a quadratic curve including a curve approximating the arc of an ellipse.

In addition, since the inclination of the beam scanning direction with respect to the direction perpendicular to the conveyance direction changes depending on the strip conveyance speed,
It is preferable that the quadratic curve that determines the curvature of the strip is also changed appropriately.

(Example) Continuous irradiation with a high energy beam according to the present invention
As shown in the figure, a strip 1 sandwiching a beam irradiation source 2
This is carried out using equipment equipped with a curving device 4 for curving the strip at the front and rear of the conveyance direction.

As this bending device, for example, the one shown in FIG. 6 or FIG. 7 is advantageously suitable.

The device shown in FIG. 6(a) consists of a drum-shaped convex roll 5 whose roll diameter increases from the axial end to the center, and a drum-shaped convex roll 5 whose diameter increases from the axial center to the end of the roll. The convex roll 5 and the concave roll 6 are arranged opposite to each other, and the roll curves of the convex roll 5 and the concave roll 6 are shaped to follow the arc of an ellipse or a circle. Through the roll skew unit 8, roll skew can be performed to change the intersection angle (roll skew angle α) between the transport direction and the roll axis on the transport line surface.

The strip 1 is then passed between a convex roll 5 and a concave roll 6 to be curved according to the roll gap, and at this time, the roll skew angle α is determined according to the conveying speed of the strip 1.
A desired concave shape can be imparted to the strip 1 by changing . The figure (bl) shows an example in which the two sets of rolls shown in figure (a) are roll-skewed in opposite directions in order to cancel the thrust force caused by the roll skew.

The device shown in FIG. 7 has a plurality of pairs of wheels 9a and 9b arranged above and below the strip conveyance path in the width direction of the conveyance path, and supports the strip 1 between the wheels 9a and 9b while at the same time bending the strip. Further, by freely controlling the position of each wheel 9a, 9b using the position control cylinder 10, an arbitrary concave shape can be provided.

Next, the continuous high-energy beam irradiation method of the present invention will be specifically described.

That is, a coil (approximately ton), line speed 30m
The electron beam is passed through the processing equipment shown in FIG.
kV, current 60mA, scanning interval 10mm, beam diameter 0.
1 mm and a vacuum degree of 3XIO-'nunHg. Regarding the electron beam irradiation area, the steel plate was curved into an elliptical arc shape such that the distance between the steel plate surface and the electron beam source in the width direction was equal to each other using the curving device shown in FIG. Further, for comparison, electron beam irradiation was performed on a steel plate curved into an arc shape under the same conditions.

When the dispersion of the iron loss value in the plate width direction of the thus obtained product was investigated, it was found to be improved by 0.002 w/kg compared to the dispersion of the product obtained in the comparative example.

(Effects of the Invention) According to the present invention, it is possible to uniformly irradiate the strip with a high-energy beam in the width direction even on the strip being conveyed, and therefore, it is possible to irradiate the strip with a high-energy beam continuously in the actual production line. It is easily achievable and greatly contributes to the industrialization of this type of processing.

[Brief explanation of the drawing]

Figures 1 (a) and (b) are explanatory diagrams showing continuous beam irradiation according to the present invention, Figure 2 is an explanatory diagram showing the beam spot shape at each irradiation position, and Figure 3 (a) and (b). 4 is a schematic diagram showing the beam scanning direction and the optimum trajectory of the beam spot. FIG. 5 is a schematic diagram of the equipment used in this invention. 6 and 7
The figure is a schematic diagram of a device for imparting curvature to a strip. 1 Strip 2-Irradiation source 3 Electron beam 4-Bending device 5=Convex roll 6-Concave roll 7-Chock 9a, 9b-Wheel

Claims (1)

[Claims] 1. A high-energy beam irradiation source fixedly arranged opposite to the strip conveyance path is scanned from a direction perpendicular to the strip conveyance direction to a direction tilted toward the conveyance direction, and the strip surface is scanned. A continuous high-energy beam irradiation method characterized in that, in irradiating the high-energy beam, the strip has a concave cross-section in a direction perpendicular to the conveying direction that curves toward the irradiation source according to a quadratic curve. 2. The method according to claim 1, wherein the strip is held in a concave shape that curves according to a quadratic curve selected depending on the conveying speed of the strip.