JP2014153275A - Irradiation window of electron ray irradiation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which a sash bar of an irradiation window has been deformed by irradiation with an electron ray, a wrinkle is generated in a thin film accompanied by the deformation of the sash bar, and if the wrinkle is repeatedly generated, durability of the thin film is reduced to make a life of the thin film shorter.SOLUTION: An irradiation window 17 of an electron ray irradiation device 3 includes a thin film 22 transmitting an electron ray E, and the thin film 22 is supported from an inside of a vacuum chamber 21 by many sash bars 25A. On a rear side of each of sash bars 25A, a slender shield member 26A is provided to be associated with each of sash bars 25A, and maintain an interval. When the electron ray E is radiated outward from the inside of the vacuum chamber 21, each shield member 26A prevents each sash bar 25 from being irradiated with the electron ray E. After the electron ray E radiated outward from the inside of the vacuum chamber 21 passes through an opening 26 between respective shield members 26A and an opening 25 between respective sash bars 25A, the electron ray E passes through the thin film 22 and a polyethylene terephthalate bottle 2 outside the vacuum chamber 2 is irradiated with the electron ray E. Since the electron ray E can prevent the sash bar 25A from being deformed by a thermal expansion, a generation of a wrinkle in the thin film 22 supported by the sash bar can be suppressed, and reduction in durability of the thin film 22 can be prevented.

Description

The present invention relates to an irradiation window of an electron beam irradiation apparatus, and more particularly, to an improvement of an irradiation window having a thin film that transmits an electron beam and a plurality of bars that support the thin film.

Conventionally, an electron beam irradiation apparatus that sterilizes a container or the like by irradiating it with an electron beam is known, and such a conventional electron beam irradiation apparatus includes an irradiation window that transmits an electron beam emitted from a vacuum chamber (patent) Reference 1 and Patent Reference 2). The conventional irradiation window includes a thin film that transmits an electron beam and a plurality of crosspieces that support the thin film from the inside of the vacuum chamber, and an electron beam emitted outward from the vacuum chamber. After passing between the bars, the material passes through the thin film and is irradiated to an object to be irradiated such as a container outside the vacuum chamber.
In the conventional electron beam irradiation apparatus, since the electron beam radiated from the vacuum chamber to the outside is also irradiated to each beam of the irradiation window, each beam of the irradiation window is known to be deformed by thermal expansion. And harmful effects are occurring. Then, the proposal for solving the problem by each beam of an irradiation window deform | transforming with an electron beam is also made | formed (for example, refer patent document 3).

Japanese Patent No. 4910819 Japanese Patent No. 5034683 JP 2001-221896 A

  By the way, as described above, the beam of the irradiation window is deformed due to thermal expansion when irradiated with the electron beam, so that the thin film is wrinkled with the deformation of the beam, and this is repeated. There was a problem that the durability of the thin film was lowered and the life was shortened.

In view of the circumstances described above, the present invention includes an irradiation window that transmits an electron beam radiated from a vacuum chamber to the outside, and the irradiation window includes a thin film that transmits an electron beam, and the thin film disposed inside the vacuum chamber. A plurality of crosspieces supported from the side, and the electron beam emitted from the vacuum chamber to the outside passes through the crosspieces and then passes through the thin film to be irradiated outside the vacuum chamber. In the irradiation window of the electron beam irradiation device designed to irradiate objects,
A plurality of shielding members are provided corresponding to each of the crosspieces and spaced from each of the crosspieces on the inner side of the vacuum chamber with respect to the crosspieces, and the electron beam is emitted from the vacuum chamber toward the outside. An electron beam is shielded by each shielding member so that each beam is not irradiated, and the electron beam emitted from the vacuum chamber to the outside passes through between each shielding member and between each beam. The object to be irradiated is irradiated through the thin film.

  According to the configuration described above, when the electron beam is emitted from the vacuum chamber toward the outside, the electron beam is not irradiated onto the beam due to the presence of the shielding member. Therefore, it is possible to prevent the crosspieces from being deformed due to thermal expansion, and thus it is possible to prevent wrinkles from forming on the thin film supported by the crosspieces. Therefore, the durability of the thin film can be prevented from being lowered as compared with the conventional case, and the life of the thin film can be extended.

1 is an overall plan view showing an embodiment of the present invention. The perspective view of the principal part of FIG. Sectional drawing of the principal part which follows the III-III line of the principal part of FIG. The front view of the principal part from the arrow IV direction of FIG. The front view of the principal part from the arrow V direction of FIG.

Hereinafter, the present invention will be described with reference to the illustrated embodiments. In FIGS. 1 and 2, reference numeral 1 denotes an electron beam sterilization apparatus. The electron beam sterilization apparatus 1 is used for a plastic bottle 2 that is sequentially transferred in an irradiation area A. By irradiating the electron beam E from the electron beam irradiation device 3, each plastic bottle 2 to be sterilized can be sterilized.
The electron beam sterilizer 1 includes a lead housing 7 that houses a carry-in wheel 4, a rotating body 5, and a carry-out wheel 6, an electron beam irradiation device 3 that is connected to one side wall 7 A of the housing 7, An upstream wheel 11 arranged on the upstream side in the transfer direction of the carry-in wheel 4 on the outside of the body 7 and a downstream wheel 12 arranged on the downstream side in the transfer direction of the carry-in wheel 6 on the outside of the housing 7 are provided.

The inside of the housing 7 is roughly divided into three by two partition members 13, 13, whereby the inside of the housing 7 is a carry-in chamber 14 on the upstream side, a sterilization chamber 15 on the center, and a carry-out chamber 16 on the downstream side. It has become. A carry-in wheel 4 is arranged in the carry-in chamber 14, and a rotating body 5 is arranged in the sterilization chamber 7. A carry-out wheel 6 is arranged in the carry-out chamber 16. An opening 7 </ b> B is formed in the upstream side wall facing the carry-in chamber 14, and an opening 7 </ b> C is also formed in the downstream side wall facing the carry-out chamber 16.

When the PET bottle 2 is supplied to the upstream wheel 11 by an upstream supply means (not shown), the PET bottle 2 is sequentially held by each gripper 11A of the upstream wheel 11 rotating in the clockwise direction, and thereafter held by the gripper 11A. The plastic bottle 2 is delivered to each gripper 4A of the carry-in wheel 4 through the opening 7B and carried into the carry-in chamber 14.
Since the carry-in wheel 4 is rotated counterclockwise in synchronization with the clockwise rotation of the rotating body 5, the plastic bottle 2 held by the gripper 4 </ b> A of the carry-in wheel 4 is transferred from the carry-in chamber 14 to the sterilization chamber 15. Thus, the paper is delivered to each gripper 5A on the rotating body 5 side at the delivery position B.
The rotating body 5 includes a plurality of grippers 5A at circumferentially equidistant positions. As the rotating body 5 rotates clockwise, each gripper 5A at the delivery position B has a gripper 4A. The plastic bottles 2 are received sequentially. And the PET bottle 2 hold | maintained at each gripper 5A with the rotation of the rotating body 5 in the clockwise direction is sequentially transferred in the irradiation area A.
An irradiation window 17 that transmits the electron beam E is provided so as to face the irradiation area A, and the electron beam E emitted from an electron beam generator (not shown) of the electron beam irradiation apparatus 3 passes through the irradiation window 17 and is irradiated. The plastic bottle 2 in the area A is irradiated. Therefore, when the PET bottles 2 held by the grippers 5A of the rotating body 5 sequentially pass through the irradiation area A, the electron beam E transmitted through the irradiation window 17 is emitted to the PET bottle 2. It has become. As a result, the PET bottle 2 held by the gripper 5A and transported through the irradiation area A is sterilized by the electron beam E. In addition, since the structure of the electron beam generation part of the electron beam irradiation apparatus 3 is well-known by the said patent documents 1, 2, etc., description of the structure of an electron beam generation part is abbreviate | omitted.

As the rotating body 5 rotates, the sterilized PET bottle 2 that has passed through the irradiation area A is transferred to the position adjacent to the carry-out chamber 16 by the gripper 5A. It is delivered from 5A to the gripper 6A on the carry-out wheel 6 side.
The carry-out wheel 6 is rotated in the counterclockwise direction in synchronization with the rotation of the rotating body 5, and the sterilized PET bottle 2 held by the gripper 6 </ b> A with the rotation of the carry-out wheel 6. Is delivered to the gripper 12 </ b> A of the downstream wheel 12 through the opening 7 </ b> C of the housing 7 and discharged from the inside of the housing 7.
As described above, the PET bottle 2 to be sterilized is carried into the sterilization chamber 15 in the housing 7 and irradiated with the electron beam E emitted from the irradiation window 17 when being transferred through the irradiation area A. Has been sterilized. In addition, the above structure regarding the electron beam sterilization apparatus 1 is already well-known by the said patent document 1,2.

  The electron beam irradiation apparatus 3 includes a box-shaped casing 20 connected to the opening 7D of the side wall 7A of the casing 7 and a vacuum chamber 21 constituted by the internal space of the casing 20. The irradiation window 17 is provided in the opening 20A on the irradiation area A side. An electron beam generating means (not shown) is provided in the vacuum chamber 21. When the electron beam E is emitted by the electron beam generating means, the electron beam E passes through the irradiation window 17 and is connected to the outside of the vacuum chamber 21. The irradiation area A of the sterilization chamber 15 is irradiated. In this embodiment, the irradiation window 17 of the electron beam irradiation apparatus 3 is configured as follows to prevent the durability of the thin film 22 provided in the irradiation window 17 from being lowered, and the thin film 22 and the irradiation window 17. This is a longer life.

As shown in FIGS. 2 to 4, the irradiation window 17 is composed of a flat window member 23, a thin film 22, and a frame member 24 that are provided fitted in the opening 20 </ b> A of the casing 20 while maintaining airtightness. It is configured. The thin film 22 is attached so as to cover the window member 23 from the outer side of the vacuum chamber 21, and the four sides and the center part are covered with the frame member 24 from the outer side and fixed to the outer surface of the window member 23. Thereby, a pair of left and right radiation surfaces 17A, 17A are formed. The thin film 22 is a titanium film having a thickness of several μm to several μm, and can transmit an electron beam E emitted from the vacuum chamber 21 to the outside.
A large number of horizontally elongated openings 25 are provided at equal pitches in the vertical direction on the radiation surfaces 17A and 17A of the window member 23, and a large number of elongated bars 25A are formed by these openings 25. Each crosspiece 25A is provided with an opening 25 so as to bend in the same direction. Thus, even if each crosspiece 25A is deformed due to thermal expansion, all the crosspieces 25A are bent in the same direction. Therefore, the width of the opening 25 does not change greatly, and the thin film 22 is not drawn into the opening 25 and the irradiation density of the electron beam E does not change. In such a configuration, when an electron beam E is emitted from the electron beam generator in the vacuum chamber 21 toward the outside, the electron beam E passes through the openings 25 between the bars 25A of the window member 23. The irradiation area A is irradiated through the thin film 22. The thin film 22 is pulled inward from the opening 25 due to a pressure difference between the inside and outside of the vacuum chamber 21, but is supported by the crosspiece 25A.

In the present embodiment, on the premise of the configuration of the irradiation window 17 described above, a plurality of elongated shielding members 26 are arranged on the back side of each beam 25A that is inside the vacuum chamber 21 so as to correspond to each beam 25A. It is a feature. That is, as shown in FIGS. 3 and 5, the plate-like shield 27 is arranged separately from each crosspiece 25 </ b> A. The shield 27 is fixed to the window member 23 by an unillustrated fixing means above the upper end opening 25 and below the lower end opening 25. The shield 27 is formed with a horizontally elongated opening 26 having the same shape at the same position as each opening 25 formed in the window member 23. The openings 26 of the shield 27 are provided at equal pitches in the vertical direction, and these openings 26 form elongated bars having the same dimensions as the above-described many bars 25A, thereby forming the shielding member 26A. Yes. When the shield 27 is connected to the back side of each radiation surface 17A by a fixing means, the back surface of each crosspiece 25A is completely shielded by the shielding member 26A. As described above, in this embodiment, each shielding member 26A is attached to the window member 23 in a state in which the shielding member 26A corresponds to each of the crosspieces 25A of the window member 23 and is separated from the corresponding crosspiece 25A.
As shown in FIGS. 3 and 5, each of the shielding members 26 </ b> A is divided in the middle, thereby absorbing the thermal expansion caused by the irradiation of the electron beam E of each shielding member 26 </ b> A and thermally expanding the shielding member 26 </ b> A. Does not protrude into the opening 26 and cover the opening 25 of the window member 23.
As a result, when the electron beam E is emitted from the electron beam generating part in the vacuum chamber 21 toward the outside of the vacuum chamber 21 (toward the irradiation area A), each shielding member 26A is inward of each crosspiece 25A. By being present on the side, each beam 25A is not directly irradiated with the electron beam E. Therefore, each beam 25A can be prevented from being deformed due to thermal expansion by the electron beam E. When the electron beam E is radiated from the inside of the vacuum chamber 21 to the outside, the electron beam E passes through the opening 26 between the shielding members 26A and the opening 25 between the crosspieces 25A. The PET bottle 2 in the irradiation area A is irradiated through the thin film 22.
As described above, the shielding member 26A is divided in the middle, and in this divided portion 26B, the one part 26Aa and the other part 26Ab of the divided shielding member 26A are in contact with each other even if thermal expansion occurs. For example, in the example shown in FIG. 3, the dividing portion 26 </ b> B is formed so as to obliquely cross the irradiation direction of the electron beam E, with a predetermined gap that is not present. The portion 26Aa is overlapped with the other portion Ab and the other portion Ab is overlapped, so that the influence of the thermal expansion of the shielding member 26A is avoided.

  Since the irradiation window 17 of the electron beam irradiation apparatus 3 in the present embodiment is configured as described above, the following effects can be obtained. That is, when the electron beam E is radiated from the inside of the vacuum chamber 21 toward the irradiation area A outside the vacuum chamber 21, the electron beam E is not directly irradiated to each beam 25A by being shielded by each shielding member 26A. It has become. Therefore, each crosspiece 25A can be prevented from being deformed by thermal expansion. Thereby, since it can suppress that a wrinkle arises in the thin film 22 supported by each crosspiece 25A, it can suppress that the durability of the thin film 22 falls compared with the past, and by extension, compared with the past. Also, the lifetime of the thin film 22 and the irradiation window 17 can be extended.

In addition to the above configuration, in this embodiment, each shielding member 26A with which the electron beam E directly collides is made of a carbon material. This is based on the knowledge that the lower the atomic number, the more the generation of braking X-rays generated by collision of electron beams can be suppressed.
That is, the window member 23 of the present embodiment closes the opening 20A of the casing 20 forming the vacuum chamber 21 in an airtight manner in a state where the opening 25 is covered with the thin film 22. Therefore, it is made of a metal material having high airtightness and rigidity, and copper is adopted in this embodiment.
However, heavy metal elements such as copper have a high atomic number and tend to generate braking X-rays. In order to prevent such X-rays from leaking to the outside, the surroundings are covered with a lead-made casing 7. However, the larger the amount of X-rays generated, the thicker the casing 7 must be and the amount of lead used. Become more. Therefore, by using a material of the shielding member 26A that shields the beam 25A of the window member 23 from the electron beam E irradiated, a material having an atomic number lower than that of the window member 23 is used to suppress the generation of braking X-rays. I have to. As a result, the effect of suppressing the generation of braking X-rays while maintaining the airtightness of the vacuum chamber 21 and reducing the amount of lead used in the housing 7 is obtained.
Note that the crosspiece 25A and the shielding member 26A may be integrally formed in the window member 23 and the shielding body 27 as illustrated in the present embodiment, or may be separately manufactured and fixed. .

2. PET bottle (irradiated object) 3. Electron beam irradiation device 17 ... Irradiation window 21 ... Vacuum chamber 22 ... Thin film 25 ... Opening 25A ... Crosspiece 26 ... Opening 26A ... Shielding member E ... Electron beam

Claims (4)

An irradiation window that transmits an electron beam emitted from the vacuum chamber to the outside is provided, and the irradiation window includes a thin film that transmits the electron beam and a plurality of bars that support the thin film from the inner side of the vacuum chamber. Has
The electron beam emitted from the vacuum chamber to the outside passes through the gaps, then passes through the thin film, and is irradiated by an electron beam irradiation apparatus that irradiates the irradiated object outside the vacuum chamber. In the window
A plurality of shielding members are provided corresponding to each of the crosspieces and spaced from each of the crosspieces on the inner side of the vacuum chamber with respect to the crosspieces, and the electron beam is emitted from the vacuum chamber toward the outside. An electron beam is shielded by each shielding member so that each beam is not irradiated, and the electron beam emitted from the vacuum chamber to the outside passes through between each shielding member and between each beam. An irradiation window of an electron beam irradiation apparatus, wherein the irradiation object is irradiated through the thin film. The irradiation window of the electron beam irradiation apparatus according to claim 1, wherein each of the shielding members is divided in the middle to avoid the influence of thermal expansion. 3. The electron beam irradiation apparatus according to claim 2, wherein one of the divided portions and the other of the divided portions of the shielding member are overlapped with each other with a predetermined gap in the irradiation direction of the electron beam. Irradiation window. The irradiation window of the electron beam irradiation apparatus according to any one of claims 1 to 3, wherein each of the shielding members is made of a material having an atomic number lower than that of the material constituting the crosspiece.

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