Electron beam irradiation device

Abstract

To provide an electron beam irradiation device that can suppress a leakage of an X-ray while maintaining nitrogen concentration within an irradiation chamber without closing a carry-in path and a carry-out path of the irradiation chamber.SOLUTION: An electron beam irradiation device according to the present disclosure comprises: a hollow almost rectangular parallelepiped irradiation chamber that irradiates a workpiece with an electron beam; a nitrogen supply unit that supplies nitrogen disposed in an upper part inside the irradiation chamber; a carry-in path that is coupled to one side of a bottom face of the irradiation chamber, and is for carrying the workpiece into the irradiation chamber; and a carry-out path that is coupled to the other side of the bottom face of the irradiation chamber, and is for carrying out the workpiece from the irradiation chamber. Each of the carry-in path and the carry-out path provided below the bottom face of the irradiation chamber at least includes: a first path that extends toward the irradiation chamber; a second path that extends upward from an end part of the first path; a third path that extends parallely along a lateral face of the irradiation chamber from an end part of the second path; and a fourth path that extends upward from an end part of the third path, and the fourth path and the bottom face of the irradiation chamber are coupled to each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an electron beam irradiation device. [Background technology]

[0002] Electron beam irradiation devices for irradiating a workpiece with an electron beam to harden the workpiece are known. Patent Document 1 discloses an ionizing radiation irradiation device that includes a transport roll that guides a transported object to be irradiated (workpiece) into an irradiation chamber where the workpiece is irradiated with an electron beam by changing the transport direction at an angle of 90 to 180 degrees, an ionizing radiation generator that irradiates the transported workpiece with ionizing radiation in the irradiation chamber, and a transport roll that changes the transport direction of the irradiated workpiece by an angle of 70 degrees or more. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-37138 Summary of the Invention [Problem to be solved by the invention]

[0004] When a workpiece is irradiated with an electron beam, nitrogen is filled inside the irradiation chamber to remove oxygen. Furthermore, X-rays are generated when the workpiece is irradiated with the electron beam. The irradiation chamber must be shielded to prevent leakage of nitrogen and X-rays from the irradiation chamber. The inventors discovered that if the entrance of the workpiece loading path and the exit of the workpiece loading path are not shielded with shutters or the like, nitrogen and X-rays may leak from the irradiation chamber. Furthermore, if the irradiation chamber is shielded with shutters or the like, the cycle time increases because of the time required to open and close the shutters.

[0005] The present disclosure has been made in consideration of the above problems, and provides an electron beam irradiation device that can suppress leakage of X-rays while maintaining the nitrogen concentration inside the irradiation chamber without closing the loading and unloading paths connected to the electron beam irradiation chamber. [Means for solving the problem]

[0006] The electron beam irradiation device according to the present disclosure is an electron beam irradiation device for irradiating an electron beam onto a workpiece to harden the workpiece, the electron beam irradiation device comprising: a hollow, approximately rectangular parallelepiped irradiation chamber that irradiates the workpiece with the electron beam; a nitrogen supply unit that supplies nitrogen and is located at the top inside the irradiation chamber; a load path connected to one side of the bottom of the irradiation chamber for loading the workpiece into the irradiation chamber; and an unload path connected to the other side of the bottom of the irradiation chamber for unloading the workpiece from the irradiation chamber, wherein the load path and the unload path, which are provided below the bottom of the irradiation chamber, each comprise at least a first path extending toward the irradiation chamber, a second path extending upward from an end of the first path, a third path extending parallel to the side of the irradiation chamber from the end of the second path, and a fourth path extending upward from the end of the third path, and the fourth path is connected to the bottom of the irradiation chamber.

[0007] The electron beam irradiation device according to the present disclosure includes a nitrogen supply unit, and a load path and a load path provided below the bottom of the irradiation chamber, each of which includes at least a first path extending toward the irradiation chamber, a second path extending upward from the end of the first path, a third path extending parallel to the side of the irradiation chamber from the end of the second path, and a fourth path extending upward from the end of the third path, the fourth path being connected to the bottom of the irradiation chamber. The nitrogen concentration in the irradiation chamber is maintained by continuously supplying nitrogen to the irradiation chamber in a laminar flow, and the workpiece transport direction is changed multiple times, thereby attenuating X-rays generated in the irradiation chamber through multiple reflections, thereby suppressing X-ray leakage. Therefore, an electron beam irradiation device can be provided that can suppress X-ray leakage while maintaining the nitrogen concentration in the irradiation chamber without closing the load path and the load path connected to the electron beam irradiation chamber. [Effects of the Invention]

[0008] The present disclosure makes it possible to provide an electron beam irradiation apparatus that can suppress leakage of X-rays while maintaining the nitrogen concentration inside the irradiation chamber without closing the carry-in and carry-out paths connected to the electron beam irradiation chamber. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a perspective view showing an electron beam irradiation device according to an embodiment; [Figure 2] 1A and 1B are a front view and a plan sectional view showing an electron beam irradiation apparatus according to an embodiment; [Figure 3] 1 is a schematic diagram and a graph showing nitrogen concentrations in electron beam irradiation devices according to an example and a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0010] Specific embodiments of the present disclosure will be described in detail below with reference to the drawings. The right-handed xyz coordinate system shown in the figure is for the convenience of explaining the positional relationships of the components. Unless otherwise specified, the positive direction of the z axis is vertically upward. The xy plane is a horizontal plane.

[0011] <Embodiment> Fig. 1 is a perspective view showing an electron beam irradiation apparatus 1 according to an embodiment. As shown in Fig. 1, the electron beam irradiation apparatus 1 according to this embodiment is an apparatus for irradiating a workpiece with an electron beam to harden the workpiece. The workpiece is, for example, a painted object covered with paint that hardens when exposed to an electron beam, a painted film that hardens when exposed to an electron beam, or the like.

[0012] 1, the electron beam irradiation device 1 includes an irradiation chamber 10, a nitrogen supply unit 11, a carry-in path 20, and an unloading path 30. The irradiation chamber 10 is a space in which the workpiece is irradiated with an electron beam, and is a hollow, approximately rectangular parallelepiped. The inner surfaces of the irradiation chamber 10, the carry-in path 20, and the unloading path 30 are coated with a material such as lead that can absorb X-rays.

[0013] In the hardening reaction caused by electron beam irradiation, the characteristics of the surface layer are important. If oxygen remains inside the irradiation chamber 10, the hardening reaction may be inhibited, which may affect the characteristics of the surface layer. Therefore, the irradiation atmosphere for irradiating the workpiece with electron beams is, for example, a nitrogen atmosphere. That is, when irradiating the workpiece with electron beams, the irradiation chamber 10 is filled with nitrogen.

[0014] As shown in Fig. 1, the nitrogen supply unit 11 is disposed at the upper interior portion of the irradiation chamber 10. The nitrogen supply unit 11 has a path that can fill nitrogen into the irradiation chamber 10. Nitrogen gas (not shown) is continuously supplied from the nitrogen supply unit 11 into the irradiation chamber 10 in a laminar flow state, filling the irradiation chamber 10.

[0015] Next, the carry-in path 20 and the carry-out path 30 will be described with reference to Fig. 2 in addition to Fig. 1. Fig. 2 is a front view (Fig. 2a) and a plan cross-sectional view (Fig. 2b) showing an electron beam irradiation apparatus according to an embodiment. As shown in Figs. 1 and 2, the carry-in path 20 and the carry-out path 30 are provided below the bottom surface 10a of the irradiation chamber 10 (on the negative side of the z-axis).

[0016] As shown in Fig. 1, the carry-in path 20 is a path for carrying a workpiece into the irradiation chamber 10. The carry-in path 20 may be connected to one side (the negative x-axis side) of the bottom surface 10a of the irradiation chamber 10. As shown in Fig. 2, the carry-out path 30 is a path for carrying a workpiece out of the irradiation chamber 10. The carry-out path 30 may be connected to the other side (the positive x-axis side) of the bottom surface 10a of the irradiation chamber 10.

[0017] The carry-in path 20 and the carry-out path 30 may have the same configuration, or may have a configuration that is symmetrical in front view and plan view (see FIG. 2). As shown in FIGS. 1 and 2, the carry-in path 20 has at least a first path 21, a second path 22, a third path 23, and a fourth path 24. The carry-out path 30 has at least a first path 31, a second path 32, a third path 33, and a fourth path 34. The first paths 21, 31, the second paths 22, 32, the third paths 23, 33, and the fourth paths 24, 34 are each, for example, approximately rectangular tubular. Each path has a cross-sectional area large enough to allow the desired workpiece to pass through. Each path also has a conveyor mechanism, an elevator mechanism, or the like that can transport the workpiece.

[0018] As shown in FIGS. 1 and 2, the carry-in path 20 includes a first path 21, a second path 22, a third path 23, and a fourth path 24, arranged in this order from the negative side of the z-axis. The first path 21 extends along the x-axis direction toward the irradiation chamber 10. The first path 21 has an inlet 21a that opens into the yz plane on the negative side of the x-axis. The second path 22 extends upward (in the positive z-axis direction) from the end of the first path 21 (on the positive x-axis side). The third path 23 extends parallel to the side surface 10b of the irradiation chamber 10 (along the y-axis) from the end of the second path 22 (in the yz plane on the positive z-axis side and the negative x-axis side). The fourth path 24 extends upward (in the positive z-axis direction) from the end of the third path 23 (in the xy plane on the positive x-axis side and the positive z-axis side). The xy plane on the positive side of the z axis of the fourth path 24 and the bottom surface 10a (xy plane) of the irradiation chamber 10 are connected.

[0019] As shown in FIG. 2(a), the discharge path 30 includes a first path 31, a second path 32, a third path 33, and a fourth path 34 arranged in this order from the negative side of the z-axis. FIG. 2(b) is a plan cross-sectional view taken along line IIB-IIB in FIG. 2(a). As shown in FIGS. 2(a) and 2(b), the first path 31 extends along the x-axis direction toward the irradiation chamber 10. The first path 31 has an outlet 31a that opens in the yz plane on the positive side of the x-axis. The second path 32 extends upward (in the positive z-axis direction) from the end of the first path 31 (the negative x-axis side). The third path 33 extends parallel to the side surface 10c of the irradiation chamber 10 (along the y-axis) from the end of the second path 32 (the yz plane on the positive z-axis and positive x-axis side). The fourth path 34 is a path that extends upward (in the positive direction of the z-axis) from the end (the x-y plane on the negative side of the x-axis and the positive side of the z-axis) of the third path 33. The x-y plane on the positive side of the z-axis of the fourth path 34 is connected to the bottom surface 10a (x-y plane) of the irradiation chamber 10.

[0020] In other words, the carry-in path 20 and the carry-out path 30 may have a path structure having four or more bending portions where the workpiece conveying direction changes by 90°.

[0021] 1 and 2 indicate the paths along which the workpiece is carried in and out of the irradiation chamber 10 from outside the electron beam irradiation device 1. First, the transport direction when the workpiece is carried in to the irradiation chamber 10 of the electron beam irradiation device 1 will be described. The workpiece is carried in through the inlet 21a of the first path 21 and transported along the first path 21 in the positive direction of the x-axis. When the workpiece enters the second path 22, the transport direction is changed by 90° and the workpiece is transported in the positive direction of the z-axis. Next, when the workpiece enters the third path 23, the transport direction is changed by 90° and the workpiece is transported in the negative direction of the x-axis across the width of the third path 23 (the width in the x-axis direction). After that, the transport direction is changed by another 90° and the workpiece is transported within the third path 23 in the negative direction of the y-axis along the side surface 10b of the irradiation chamber 10. Next, the transport direction is changed by 90° when entering the fourth path 24, and the material is transported in the positive direction of the x-axis within the third path 23 and the fourth path 24, after which the transport direction is changed again by 90° and the material is transported in the positive direction of the z-axis, and then transported to the irradiation chamber 10.

[0022] Next, the transport direction when the workpiece is transported from the irradiation chamber 10 to the outside of the electron beam irradiation device 1 will be described. After electron beam irradiation in the irradiation chamber 10, the workpiece is transported in the negative z-axis direction within the fourth path 34. Next, the transport direction is changed by 90 degrees, and the workpiece is transported in the negative x-axis direction across the width of the third path 33 (width in the x-axis direction). Then, the transport direction is changed by another 90 degrees, and the workpiece is transported in the positive y-axis direction within the third path 33 along the side surface 10c of the irradiation chamber 10. Then, the transport direction is changed by another 90 degrees, and the workpiece is transported in the positive x-axis direction within the third path 33. Next, when entering the second path 32, the transport direction is changed by 90 degrees, and the workpiece is transported in the negative z-axis direction. Next, when entering the first path 31, the transport direction is changed by 90 degrees, and the workpiece is transported in the positive x-axis direction, and the workpiece is transported out of the electron beam irradiation device 1.

[0023] In this embodiment, the carry-in path and the carry-out path are disposed on the positive and negative x-axis sides of the bottom surface of the irradiation chamber, but are not limited thereto as long as they are disposed below the bottom surface of the irradiation chamber. For example, they may be disposed below the bottom surface of the irradiation chamber so that the portion of the carry-in path connected to the bottom surface of the irradiation chamber does not overlap with the portion of the carry-out path connected to the bottom surface of the irradiation chamber. More specifically, for example, both the carry-in path and the carry-out path may be disposed on one side (negative x-axis side) of the bottom surface of the irradiation chamber.

[0024] In the present embodiment, the second paths 22, 32 are disposed directly below the bottom surface 10a of the irradiation chamber 10, but this is not limiting. For example, the second paths 22, 32 may be disposed on the negative or positive x-axis side of the irradiation chamber. In other words, the portions of the third paths 23, 33 connected to the fourth paths 24, 34 and the fourth paths 24, 34 may be disposed directly below the irradiation chamber 10 (negative z-axis side), and the ends of the first paths 21, 31, the second paths 22, 32, and the third paths 23, 33 may be disposed at any position on the negative or positive z-axis side of the bottom surface 10a of the irradiation chamber 10.

[0025] The inventors discovered that if the entrance of the loading route for carrying the workpiece into the irradiation chamber and the exit of the unloading route are not shielded by shutters or the like, there is a risk of nitrogen and X-rays leaking from the irradiation chamber, and if a shutter or the like is installed to shield the irradiation chamber, it takes time to open and close the shutter, which increases the cycle time.

[0026] In contrast, the electron beam irradiation apparatus according to the present disclosure includes a nitrogen supply unit, and an inlet and outlet paths provided below the bottom of the irradiation chamber, each of which includes at least a first path extending toward the irradiation chamber, a second path extending upward from the end of the first path, a third path extending parallel to the side of the irradiation chamber from the end of the second path, and a fourth path extending upward from the end of the third path, with the fourth path connected to the bottom of the irradiation chamber. Continuously supplying nitrogen to the irradiation chamber in a laminar flow manner can maintain the nitrogen concentration within the irradiation chamber. In other words, continuously supplying nitrogen to the irradiation chamber in a laminar flow manner can suppress the inflow of oxygen from the inlet of the inlet path and the outlet of the outlet path, thereby maintaining the oxygen concentration within the irradiation chamber at a desired level or lower. Furthermore, by changing the transport direction of the workpiece multiple times, X-rays generated within the irradiation chamber are reflected and attenuated multiple times, thereby suppressing X-ray leakage. Therefore, it is possible to suppress leakage of X-rays while maintaining the nitrogen concentration inside the irradiation chamber without closing the carry-in and carry-out paths connected to the electron beam irradiation chamber.

[0027] Furthermore, the electron beam irradiation device according to the present disclosure does not require shutters or the like to close the connecting portions between the irradiation chamber and the carry-in and carry-out paths, which means that the time required for opening and closing a shutter is not required, and therefore the cycle time when continuously transporting workpieces to the electron beam irradiation device can be significantly reduced. [Example]

[0028] The present disclosure will be described in detail below based on examples, but the present disclosure is not limited to these examples. In the examples and comparative examples, a simulation of the nitrogen concentration in the irradiation chamber when irradiating a workpiece with an electron beam was performed. In the examples, the electron beam irradiation apparatus shown in FIG. 1 according to the above-described embodiment was used. That is, an electron beam irradiation apparatus was used in which nitrogen was continuously supplied to the irradiation chamber in a laminar flow and which had an inlet path shaped with four or more bending sections below the bottom of the irradiation chamber where the workpiece transport direction was changed. The differences between the examples and comparative examples 1 and 2 are the arrangement and shape of the inlet path and the outlet path. For comparative examples 1 and 2, an electron beam irradiation apparatus with a linear inlet path was used. Details will be described later using FIG. 3.

[0029] Fig. 3 is a schematic diagram and graph showing the nitrogen concentration in the electron beam irradiation apparatus according to the example and the comparative example. Fig. 3(a) is a schematic front view of the example, Fig. 3(b) is a schematic front view of Comparative Example 1, Fig. 3(c) is a schematic front view of Comparative Example 2, and Fig. 3(d) is a graph showing the simulation results of the nitrogen concentration in Fig. 3(a), Fig. 3(b), and Fig. 3(c).

[0030] As shown in Fig. 3(a), the irradiation chamber 10 of the electron beam irradiation apparatus according to the embodiment includes a nitrogen supply unit 11 capable of continuously supplying nitrogen in a laminar flow to the irradiation chamber 10, and a carry-in path 20 having four or more bent sections below the bottom surface of the irradiation chamber 10, where the workpiece transport direction is changed by 90°. As shown in Figs. 3(a) and 3(d), the electron beam irradiation apparatus according to the embodiment achieved results in which the nitrogen concentration in the irradiation chamber 10 was maintained at or above the concentration required for electron beam irradiation. In other words, the inflow of oxygen from the carry-in opening 21a of the carry-in path 20 was suppressed.

[0031] As shown in FIG. 3(b), the carry-in path 120 according to Comparative Example 1 is linear and connected to the side surface on the bottom side of the irradiation chamber 110. The height from the placement surface B on which the bottom surface of the carry-in entrance 121a is placed to the ceiling surface 121b of the carry-in entrance 121a is defined as H1. The height from the placement surface B to the bottom surface 110a of the irradiation chamber 110 is defined as H2. In Comparative Example 1, the carry-in path 120 is arranged to have an upward slope to the right when viewed from the front, such that H1>H2. That is, the carry-in path 120 is arranged so that the ceiling surface 121b of the carry-in entrance 121a is above the bottom surface 110a of the irradiation chamber 110.

[0032] In the electron beam irradiation device according to Comparative Example 1, as shown in Fig. 3(b), a large amount of oxygen flowed in from the carry-in port 121a of the carry-in path 120, and the nitrogen concentration in the irradiation chamber 10 was lower than the concentration required for electron beam irradiation. As shown in Fig. 3(d), in Comparative Example 1 in which the carry-in path 120 was connected to the side of the irradiation chamber 110, the nitrogen concentration in the irradiation chamber 110 was lower than the nitrogen concentration in the irradiation chamber 10 of the electron beam irradiation device according to the example in which the carry-in path was connected below the bottom surface of the irradiation chamber.

[0033] As shown in FIG. 3(c), the carry-in path 220 according to Comparative Example 2 is linear like that of Comparative Example 1 and is connected to the side surface on the bottom side of the irradiation chamber 210. The height H1 is defined as the height from the placement surface B on which the bottom surface of the carry-in entrance 221a is placed to the ceiling surface 221b of the carry-in entrance 221a. The height H1 of Comparative Example 1 and the height H1 of Comparative Example 2 are the same height. The height H3 is defined as the height from the placement surface B to the bottom surface 210a of the irradiation chamber 210. In Comparative Example 2, the carry-in path 220 is arranged to have an upward slope to the right when viewed from the front, so that H1 = H3. In other words, the carry-in path 220 is arranged so that the ceiling surface 221b of the carry-in entrance 221a and the bottom surface 210a of the irradiation chamber 210 are at the same height.

[0034] In the electron beam irradiation device according to Comparative Example 2, as shown in FIG. 3(c), oxygen flowed in from the carry-in port 221a of the carry-in path 220, and the nitrogen concentration in the irradiation chamber 10 was lower than the concentration required for electron beam irradiation. In Comparative Example 2, the ceiling surface 221b of the carry-in port 221a and the bottom surface 210a of the irradiation chamber 210 were arranged to be at the same height. In other words, the height H3 from the placement surface B to the bottom surface 210a of the irradiation chamber 210 was greater than the height H2 from the placement surface B to the bottom surface 110a of the irradiation chamber 110 in Comparative Example 1 (see FIG. 3(b)). With this configuration, as shown in FIG. 3(d), a higher nitrogen concentration was obtained in the irradiation chamber 210 compared to Comparative Example 1. However, as shown in Figure 3(d), in Comparative Example 2, in which the loading path 220 is connected to the side of the irradiation chamber 210, the nitrogen concentration in the irradiation chamber 210 was lower than the nitrogen concentration in the irradiation chamber 10 of the electron beam irradiation device of the embodiment in which the loading path is connected below the bottom surface of the irradiation chamber.

[0035] From the above results, it was found that the electron beam irradiation apparatus according to this embodiment can maintain the nitrogen concentration in the irradiation chamber by continuously supplying nitrogen in a laminar flow to the irradiation chamber and by having a carry-in path with four or more bending sections below the bottom of the irradiation chamber where the workpiece transport direction is changed. Therefore, the electron beam irradiation apparatus according to this embodiment can maintain the nitrogen concentration in the irradiation chamber without closing the carry-in path and the carry-out path connected to the electron beam irradiation chamber.

[0036] The present disclosure is not limited to the above-described embodiment, and can be modified as appropriate within the scope of the present disclosure. [Explanation of symbols]

[0037] 1 electron beam irradiation device, 10, 110, 210 irradiation chamber, 10a bottom surface, 10b, 10c side surface, 11 nitrogen supply unit, 12 filter, 20, 120, 220 carry-in path, 21, 31 first path, 21a, 121a, 221a carry-in entrance, 22, 32 second path, 23, 33 third path, 24, 34 fourth path, 30 carry-out path, 31a carry-out exit, 121b, 221b ceiling surface, B placement surface, H1, H2, H3 height

Claims

[Claim 1] An electron beam irradiation device for irradiating an electron beam onto a workpiece to harden the workpiece, The electron beam irradiation device is a hollow, substantially rectangular parallelepiped irradiation chamber for irradiating the workpiece with the electron beam; a nitrogen supply unit disposed in an upper portion inside the irradiation chamber and configured to continuously supply nitrogen into the irradiation chamber in a laminar flow state; a carry-in path connected to one side of a bottom surface of the irradiation chamber and used to carry the work into the irradiation chamber; a carry-out path connected to the other side of the bottom surface of the irradiation chamber and for carrying the work out of the irradiation chamber, The carry-in path and the carry-out path provided below the bottom surface of the irradiation chamber are each a first path extending toward the irradiation chamber; a second path extending upward from an end of the first path; a third path extending from an end of the second path in parallel along a side surface of the irradiation chamber; a fourth path extending upward from the end of the third path and disposed directly below the bottom surface of the irradiation chamber; The fourth path is connected to a bottom surface of the irradiation chamber. Electron beam irradiation equipment.

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