Attachment

Abstract

To provide an attachment that allows a cap to be reused and allows easy separation when disposed.SOLUTION: An attachment capable of attaching a cap of the present invention comprises: a cylindrical part to which the cap can be attached; fixing and supporting means which fixes and supports a magnet on a side opposite to an attaching side in an axial direction of the cylindrical part; and diameter expanding means which expands an inner diameter of the cylindrical part to allow the magnet to be attached and detached.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an attachment, and more particularly to an attachment to which a cap can be attached. [Background technology]

[0002] In recent years, environmentally friendly efforts have been required from the perspective of CSR (Corporate Social Responsibility). Containers sealed with caps are recyclable except for the cap, so they are collected and reused after the contents have been consumed. However, from a hygiene standpoint, it is difficult to reuse caps as caps to seal containers filled with contents.

[0003] For example, Patent Document 1 describes a notice device that uses a plastic bottle cap with a specific design to express various designs and that can make effective use of the plastic bottle cap. Specifically, Patent Document 1 describes a notice device that is composed of a plastic bottle cap with a threaded portion on the inside and a cylindrical member with a locking portion on the outer periphery that fits and is fixed to the threaded portion, with a specific design on the top surface of the cap, a flange at the bottom end of the cylindrical member with an outer diameter that is approximately the same as or slightly larger than the outer diameter of the cap, and a magnet on the bottom surface of the cylindrical member that can be attached and detached to a wall, board, furniture, etc.

[0004] Furthermore, Patent Document 2 describes a liquid container cap that can hold documents and other objects by the magnetic force of a magnet and has a mark on the surface of the top plate, making it reusable. Specifically, Patent Document 2 describes a fastener that is characterized by comprising a fastener main body having a locking portion that locks to the inside of the liquid container cap, and a magnet fixed to the fastener main body. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-99176 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-106870 Summary of the Invention [Problem to be solved by the invention]

[0006] In the conventional technology described above, there is an environmental problem in that when attachments such as fasteners are disposed of, it is difficult to remove the magnets from the attachments, making separation difficult.

[0007] SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide an attachment that allows the cap to be reused and that allows easy separation when discarded. [Means for solving the problem]

[0008] In order to solve the above problems, one form of the attachment of the present invention is characterized in that (1) an attachment to which a cap can be attached comprises a cylindrical portion to which the cap can be attached, a fixing and supporting means for fixing and supporting a magnet on the axial side of the cylindrical portion opposite the side to which the cap is attached, and a diameter expanding means for expanding the inner diameter of the cylindrical portion and for allowing the magnet to be attached and detached.

[0009] In the attachment described in (1) above, (2) it is preferable that the diameter expanding means includes a notch provided on at least the side of the cylindrical portion on the mounting side of the cap.

[0010] In the attachment described in (1) above, (3) it is preferable that the diameter expanding means is provided on a side surface of the cylindrical portion and includes a slit that penetrates the cylindrical portion along the axial direction.

[0011] Furthermore, in the attachment described in any one of (1) to (3) above, (4) it is preferable that the fixing support means includes: a first protrusion provided on the inner surface of the cylindrical portion and protruding radially inward of the cylindrical portion, capable of supporting the main surface of the magnet on the opposite side to the side where the cap is attached; and a second protrusion provided on the inner surface on the side where the cap is attached relative to the first protrusion and protruding radially inward, capable of overriding the magnet when attached and capable of fixing the main surface of the magnet on the side where the cap is attached.

[0012] Furthermore, in the attachment described in any one of (1) to (4) above, it is preferable that (5) it further comprises a diameter reducing means that interferes with the inner surface of the bottom of the cap when the cap is attached, thereby applying a tightening force to the cylindrical portion in a radially inward direction to the cylindrical portion.

[0013] Furthermore, in the attachment described in (5) above, (6) it is preferable that the tubular portion further comprises a flange protruding radially outward from the tubular portion on the side opposite to the side on which the cap is attached, and that the diameter reducing means includes an inclined surface that stands upright from the flange along the axial direction of the tubular portion and faces the inner bottom surface of the cap when the cap is attached.

[0014] Furthermore, in the attachment described in any one of (1) to (6) above, (7) it is preferable that the tubular portion further includes a threaded portion onto which the cap can be screwed, and that the diameter expansion means is provided in a region of the tubular portion that is 270° or more but less than 360° clockwise from the threading start end of the threaded portion when viewed from the side on which the cap is attached. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide an attachment that allows the cap to be reused and that allows easy separation when discarded. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a diagram showing the appearance of an attachment according to an embodiment of the present invention; [Figure 2] 1 is a cross-sectional view through the central axis of an attachment according to an embodiment of the present invention, with a cap and magnet attached; FIG. [Figure 3] 1 is a schematic diagram of an attachment according to an embodiment of the present invention, viewed from the side where a cap is attached. [Figure 4] 10A and 10B are schematic diagrams illustrating the attachment and detachment of a magnet to an attachment according to one embodiment of the present invention. [Figure 5] 1 is a schematic diagram illustrating an attachment according to an embodiment of the present invention, with a magnet attached thereto; [Figure 6] FIG. 3 is a partial enlarged view of the α region indicated by the dashed line in FIG. 2, illustrating the state of diameter reduction. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, preferred embodiments of the present invention will be described. In the following explanations using the drawings, the X, Y, and Z directions are appropriately defined, but these are definitions given for the sake of convenience and do not unduly limit the present invention.

[0018] <1. Attachment> 1 and 2, an attachment 1 according to this embodiment will be described. The attachment 1 is an attachment onto which a cap 2 can be attached. Specifically, the attachment 1 includes a cylindrical portion 10 onto which the cap 2 can be attached, a fixing and supporting means 20 that can fix and support a magnet 3 on the side of the cylindrical portion 10 opposite the side onto which the cap 2 is attached in the axial direction (Z direction in FIG. 2), and a diameter expanding means 30 that can expand the inner diameter of the cylindrical portion 10, thereby enabling the magnet 3 to be attached and detached.

[0019] (cap) The cap 2 may be any known or arbitrary cap used for opening and closing beverage containers such as PET bottles, for example, a synthetic resin cap molded into a desired shape by press molding or injection molding, but the present invention is not limited thereto. Specifically, the cap 2 has a cylindrical shape and is provided with a thread on its inner surface. The thread may have any known or arbitrary structure.

[0020] (magnet) The magnet 3 has a shape that allows it to be attached to and detached from the cylindrical portion 10 when the inner diameter of the cylindrical portion 10 is expanded by the diameter expanding means 30. Specifically, the magnet 3 has a cylindrical shape whose outer diameter is smaller than the inner diameter of the cylindrical portion 10. The material of the magnet 3 is any known or arbitrary material that has a magnetic force that allows it to hold documents, etc., sandwiched between the attachment 1 and a metal plate, etc., by magnetic attraction, but the present invention is not limited to this.

[0021] (Cylindrical part) 1 and 2, the cylindrical portion 10 has a shape that allows the cap 2 to be attached. Specifically, the cylindrical portion 10 is hollow and has a cylindrical shape whose outer diameter is smaller than the inner diameter of the cap 2. The cylindrical portion 10 also includes a first inner surface 12a that can fasten the magnet 3 with a fastening force, which will be described later, and a second inner surface 12b that is provided on the attachment side of the cap 2 from the first inner surface 12a and has a larger inner diameter than the first inner surface 12a. However, the inner diameter of the second inner surface 12b may be the same as the inner diameter of the first inner surface 12a.

[0022] The cylindrical portion 10 preferably includes a threaded portion 14 onto which the cap 2 can be screwed. Specifically, a threaded portion is formed on the outer surface of the cylindrical portion 10, which can be screwed onto a thread formed on the inner surface of the cap 2 when the cap 2 is attached. The threaded portion may have any known or arbitrary structure.

[0023] Preferably, the cylindrical portion 10 further includes a flange 16 that protrudes radially outward from the cylindrical portion 10 on the side opposite to the side where the cap 2 is attached. The flange 16 preferably protrudes radially outward from the cap 2 when the cap 2 is attached. With particular reference to FIG. 2, the diameter of the flange 16 is preferably equal to or greater than the outermost diameter of the cap 2. This allows the flange 16 to be securely held when the cap 2 is attached to the attachment 1. Returning to FIG. 1, the flange 16 is continuous along the circumferential direction of the cylindrical portion 10, but has a gap at the position where the diameter expansion means 30 is provided. The size of the gap can be set appropriately taking into account the width of a slit corresponding to the diameter expansion means 30, which will be described later.

[0024] (fixed support means) 1 and 2, the fixing support means 20 is capable of fixing and supporting the magnet 3 on the side of the cylindrical portion 10 opposite the side where the cap 2 is attached in the axial direction (Z direction in FIG. 2). Referring particularly to FIG. 2, the fixing support means 20 is preferably provided on the inner surface (specifically, the first inner surface 12a) of the cylindrical portion 10 and includes a first protrusion 20a that protrudes radially inward of the cylindrical portion 10. The first protrusion 20a is preferably capable of supporting the main surface 3b of the magnet 3 on the side opposite the side where the cap 2 is attached. Note that the protrusion length L1 of the first protrusion 20a can be set appropriately so as to prevent the magnet 3 from falling off and to exhibit magnetic attraction.

[0025] 3, from the viewpoint of stably supporting the magnet 3 and exerting a magnetic attraction effect, it is preferable that a plurality of first protrusions 20a are formed intermittently along the circumferential direction on the inner surface (specifically, the first inner surface 12a) of the cylindrical portion 10. Here, the first protrusions 20a may each have the same shape, and may be arranged at equal intervals along the circumferential direction on the inner surface (specifically, the first inner surface 12a) of the cylindrical portion 10. Furthermore, from the viewpoint of preventing the magnet 3 from falling when attaching the magnet 3 to the cylindrical portion 10, the length along the circumferential direction of the cylindrical portion 10 of the first protrusions 20a located on the diameter expansion means 30 side may be longer than the length along the circumferential direction of the cylindrical portion 10 of the first protrusions 20a located on the opposite side of the diameter expansion means 30. 3, four first protrusions 20a are arranged at equal intervals along the circumferential direction of the cylindrical portion 10, but the present invention is not limited to this, and the number and arrangement of the first protrusions 20a can be set as appropriate. However, from the viewpoint of stably supporting the magnet 3, it is preferable that the number of first protrusions 20a be three or more, and that they be arranged at equal intervals. In this case, it is more preferable that at least two first protrusions 20a are provided on the circumference of the cylindrical portion 10 on the diameter expansion means 30 side in the XY cross section of the cylindrical portion 10. It is also preferable that the first protrusions 20a are continuous along the circumferential direction of the cylindrical portion 10 on the inner surface of the cylindrical portion 10 (specifically, the first inner surface 12a).

[0026] 1 and 2, the fixing support means 20 is preferably provided on the inner surface (specifically, the first inner surface 12a) of the cylindrical portion 10 closer to the attachment side of the cap 2 than the first protrusion 20a, and includes a second protrusion 20b that protrudes radially inward of the cylindrical portion 10. The second protrusion 20b preferably enables the magnet 3 to climb over it when the magnet 3 is attached, and is capable of fixing the main surface 3a of the magnet 3 on the attachment side of the cap 2. The protrusion length L2 of the second protrusion 20b can be set appropriately so as to prevent the magnet 3 from falling off and to exhibit magnetic attraction.

[0027] In a cross section passing through the axis of the cylindrical portion 10, the second protrusion 20b includes a first inclined portion θ1 continuing from the first protrusion 20a side of the first inner surface 12a, and a second inclined portion θ2 located closer to the attachment side of the cap 2 than the first inclined portion θ1 and continuing to the first inner surface 12a, and it is preferable that the inclination angle of θ2 in the Z direction is smaller than the inclination angle of θ1. This is because the first inclined portion θ1 needs to make the magnet 3 easy to attach and detach while making it difficult to come off when the attachment 1 is in use, and the second inclined portion θ2 is specialized for the attachment of the magnet 3. Note that a straight portion may be provided between the first inclined portion θ1 and the second inclined portion θ2.

[0028] Referring also to FIG. 3, from the viewpoint of stably fixing the magnet 3, it is preferable that a plurality of second protrusions 20b are formed intermittently along the circumferential direction of the tubular portion 10 on the inner surface (specifically, the first inner surface 12a) of the tubular portion 10. Here, the second protrusions 20b may each have the same shape and may be arranged at equal intervals along the circumferential direction of the tubular portion 10 on the inner surface (specifically, the first inner surface 12a) of the tubular portion 10. Note that in FIG. 3, four second protrusions 20b are arranged at equal intervals along the circumferential direction of the tubular portion 10, but the present invention is not limited to this, and the number and arrangement of the second protrusions 20b can be set as appropriate. However, from the viewpoint of stably fixing the magnet 3, it is preferable that the number of second protrusions 20b is three or more, and that they are arranged at equal intervals. In this case, it is more preferable that at least two second protrusions 20b are provided on the diameter expanding means 30 side of the circumference of the cylindrical portion 10 in the XY cross section of the cylindrical portion 10. Furthermore, as illustrated in Fig. 3, the second protrusions 20b may be arranged at equal intervals along the circumferential direction so that at least a portion of the second protrusions 20b overlaps with the first protrusions 20a in the axial direction.

[0029] 2, from the viewpoint of stably supporting the magnet 3, it is preferable that the protruding length L1 of the first protruding portion 20a is longer than the protruding length L2 of the second protruding portion 20b. Note that the height positions of the first protruding portion 20a and the second protruding portion 20b are not particularly limited as long as the magnet 3 can be fitted between the first protruding portion 20a and the second protruding portion 20b, and can be set appropriately taking into account the thickness of the magnet 3, etc.

[0030] (diameter expansion means) 1, the diameter expanding means 30 enables the inner diameter of the cylindrical portion 10 to be expanded, thereby enabling the attachment and detachment of the magnet 3. That is, when attaching the magnet 3, the diameter expanding means 30 is used to expand the inner diameter of the cylindrical portion 10 in the direction of arrow Y1 as shown in Fig. 4, while the magnet 3 is pushed into the attachment 1 in the direction of arrow Y2, thereby enabling the magnet 3 to be attached to the attachment 1 as shown in Fig. 5. On the other hand, when removing the magnet 3, the diameter expanding means 30 is used to expand the inner diameter of the cylindrical portion 10 in the direction of arrow Y1 as shown in Fig. 4, while the magnet 3 is pushed out of the attachment 1 in the direction of arrow Y3, thereby enabling the magnet 3 to be removed.

[0031] 1 and 3, the diameter expanding means 30 preferably includes a slit 32 provided on the side surface of the tubular portion 10 and penetrating the tubular portion 10 along the axial direction. Particularly referring to FIG. 3, the slit 32 preferably has a width set so that, when viewed from the side where the cap 2 is attached, an angle formed between a line passing through one end of the slit 32 in the penetrating direction and the center of the tubular portion 10 and a line passing through the other end of the slit 32 in the penetrating direction and the center of the tubular portion 10 is greater than 0° and less than 90°. Having a slit width within the above range allows for sufficient exertion of the tightening force described below and ensures stable attachment of the cap 2. In this specification, the term "slit" refers to a gap provided on the side surface of the tubular portion 10 and penetrating the tubular portion 10 along the axial direction. In this specification, the term "slit width" refers to the circumferential spacing of the inner surface of the tubular portion 10 (specifically, the second inner surface 12b) when viewed from the side where the cap 2 is attached.

[0032] 3, when the tubular portion 10 has the threaded portion 14, the diameter expanding means 30 is preferably provided in a region of the tubular portion 10 that is 270° or more and less than 360° clockwise from the thread cutting start end 14s of the threaded portion 14 of the tubular portion 10, as viewed from the side where the cap 2 is attached. For example, when a slit 32 is used as the diameter expanding means 30, the slit 32 is preferably provided in a region of the tubular portion 10 that is 270° or more and less than 360° clockwise from the thread cutting start end 14s of the threaded portion 14 of the tubular portion 10, as viewed from the side where the cap 2 is attached. This allows the threads of the cap 2 to enter the region of the slit 32 while engaged with the tubular portion 10 by at least 270°, thereby preventing the cap 2 from being obliquely overlapped and falling off the threaded portion 14.

[0033] (diameter reduction means) Referring to Figures 1 and 2, it is preferable that the attachment 1 further includes a diameter reducing means 40 that interferes with the inner bottom surface 2a of the cap 2 when the cap 2 is attached, thereby applying a tightening force to the tubular portion 10 toward the radially inward direction of the tubular portion 10.

[0034] When the cylindrical portion 10 includes a flange 16, the diameter reducing means 40 preferably extends from the flange 16 along the axial direction of the cylindrical portion 10 and includes an inclined surface 44 that faces the inner bottom surface 2a of the cap 2 when the cap 2 is attached. Specifically, the diameter reducing means 40 preferably extends from the flat surface of the flange 16 on the attachment side of the cap 2 (hereinafter also referred to as the "flange surface 16a") along the axial direction of the cylindrical portion 10 and includes an inclined portion 42 that continues along the circumferential direction of the cylindrical portion 10, sandwiching the diameter expanding means 30 therebetween. The inclined portion 42 preferably includes an inclined surface 44 that faces the inner bottom surface 2a of the cap 2 when the cap 2 is attached. As a result, when the cap 2 is attached, the inclined surface 44 interferes with the inner bottom surface 2a of the cap 2, thereby reducing the width of the slit corresponding to the diameter expanding means 30 and tightening the magnet 3, thereby preventing the magnet 3 from coming off when the attachment 1 is in use. More specifically, when the cap 2 is seamed onto the attachment 1, the outer periphery of the inclined surface 44 is pressed toward the inner diameter by the inner bottom surface 2a of the cap by the overlap L6 shown in FIG. 6, thereby reducing the diameter of the attachment 1. The inclined portions 42 may be provided piecemeal, rather than continuously, along the circumferential direction of the cylindrical portion 10. However, from the viewpoint of preventing the magnet 3 from detaching, it is preferable to provide three or more inclined portions 42, and it is preferable to provide them at equal intervals. With particular reference to FIG. 3 , it is more preferable that, in the XY plane of the cylindrical portion 10, at least two inclined portions 42 are provided on the circumferential side of the cylindrical portion 10 facing the diameter expansion means 30, spaced apart by predetermined intervals L4 and L5 from the diameter expansion means 30. It is preferable that the predetermined intervals L4 and L5 be greater than 0° and less than 90° (L3 + L4 + L5) along the circumferential direction of the inner surface (specifically, the second inner surface 12b) of the cylindrical portion 10. If the angle is greater than 0°, the rigidity of the cylindrical portion 10 decreases, making it easier to attach and detach the magnet 3. If the angle is 90° or less, there is no problem in terms of exerting fastening force. Here, L3 means the circumferential spacing of the second inner surface 12b of the cylindrical portion 10 when viewing the cylindrical portion 10 from the side where the cap 2 is attached. Note that the inclined portions 42 may be arranged intermittently.

[0035] 6, when the nominal diameter of the cap is 28 mm, the erection height H1 of the inclined portion 42 is more preferably 3 mm or less. This is because a height of 3 mm or less allows the cap 2 to be easily attached. From the viewpoint of tightening force and ease of attachment of the cap 2, the inclination angle θ of the inclined surface 44 is more preferably 45° or more, and in terms of radial dimensions, the outer diameter of the tip of the inclined portion 42 is preferably 22 mm or more and 28 mm or less, and the outer diameter of the base of the inclined portion 42 is preferably 28 mm or more. In this specification, the "inclination angle" refers to the angle between the inclined surface 44 and the flange surface 16a.

[0036] <2. Attachment manufacturing method> An example of a manufacturing method for the attachment 1 according to this embodiment will be briefly described. The attachment 1 according to this embodiment can be manufactured by a known or arbitrary injection molding method using an injection mold that molds the outer shape of the attachment 1. Specifically, the attachment 1 is obtained by forcing heated and molten resin into an injection mold that molds the outer shapes of the tubular portion 10, the fixing and supporting means 20, the diameter expansion means 30, and the diameter reduction means 40 that make up the attachment 1 at a predetermined injection pressure and then cooling the resin after molding. The resin may be a synthetic resin such as polyethylene or polypropylene that is soft enough to allow the diameter expansion means 30 to deform, but the present invention is not limited to these. The multiple cavities provided on the outer surface of the tubular portion 10 shown in FIG. 1 and other figures are formed by an extrusion mechanism or the like for releasing the attachment 1 from the injection mold and are not essential for achieving the effects of the present invention.

[0037] In addition, instead of preforming the outer shape of the expansion means 30 in an injection molding mold, the expansion means 30 may be formed by scraping off a portion of the outer periphery of the tubular portion 10 using a known or arbitrary method after injection molding.

[0038] (effect) The attachment 1 of this embodiment described above is characterized by mainly comprising a tubular portion 10 to which the cap 2 can be attached, a fixing and supporting means 20 that can fix and support the magnet 3 on the axial side of the tubular portion 10 opposite the side on which the cap 2 is attached, and a diameter expanding means 30 that can expand the inner diameter of the tubular portion 10 so that the magnet 3 can be attached and detached.

[0039] According to this configuration, the magnet 3 can be attached to the attachment 1 by using the diameter expansion means 30 to expand the inner diameter of the cylindrical portion 10 and pushing the magnet 3 into the attachment 1 from the side where the cap 2 is attached. Meanwhile, the magnet 3 can be removed by using the diameter expansion means 30 to expand the inner diameter of the cylindrical portion 10 and pushing the magnet 3 out from the side opposite the side where the cap 2 is attached toward the attachment side. This makes it possible to reuse the cap 2 and facilitates separation when disposing of the attachment 1. However, the direction in which the magnet 3 is attached and detached is not necessarily limited to the above-described direction. For example, the magnet 3 may be attached to the attachment 1 from the side opposite the side where the cap 2 is attached toward the attachment side. Furthermore, the magnet 3 may be pushed out from the side where the cap 2 is attached toward the opposite side of the attachment 1.

[0040] The above-described embodiment is merely an example, and various modifications are possible, including combinations of the various embodiments, without departing from the spirit of the present invention. The above-described embodiment may also include optional components not shown in the drawings. Furthermore, the components shown in the drawings may be modified or omitted without departing from the spirit of the present invention.

[0041] As a modification, the diameter expanding means of the present invention may include a notch provided on at least the side of the cylindrical portion on the side where the cap is attached, instead of the slit. The width of the notch can be set to the same as the width of the slit.

[0042] As a modified example, the diameter expanding means of the present invention may be a thin-walled portion or a flexible portion provided at a location corresponding to the slit or notch, instead of the slit or notch. In this specification, the term "thin-walled portion" refers to a region of the tubular portion that is thinner than the thickness of the area other than where the thin-walled portion is provided. In addition, in this specification, the term "flexible portion" refers to a portion of the tubular portion that has a higher elastic modulus than the elastic modulus of the area other than where the flexible portion is provided. For example, if the tubular portion is mainly made of resin, the flexible portion may be made of an elastic material such as rubber.

[0043] As a modified example, the cylindrical portion of the present invention does not necessarily have to include the threaded portion described above. That is, the cap does not necessarily have to be attached to the cylindrical portion by screwing, but the cylindrical portion itself may be made of a known or arbitrary material so as to be flexible inward and outward in the radial direction, and the cap may be attached by the elastic force of the cylindrical portion.

[0044] As a modified example, the attachment is not limited to being made of resin as described above, but may be made of metal such as aluminum. [Industrial Applicability]

[0045] The present invention is suitable for providing an attachment that allows the cap to be reused and that allows for easy separation when discarded. [Explanation of symbols]

[0046] 1: Attachment 2: Cap 2a: Inside of hem 3: Magnet 3a: First main surface 3b: Second main surface 10: Cylindrical part 12a: First inner surface 12b: Second inner surface 14: Threaded part 14s: Thread start point 16: Flange 16a: Flange surface 20: Fixed support means 20a: First protrusion 20b: Second protrusion θ1: First inclined portion θ2: Second inclined portion 30: Diameter expansion means 32: Slit 40: Diameter reduction means 42: Inclined part 44: Inclined surface

Claims

1. For attachments that can be fitted with caps, a cylindrical portion to which the cap can be attached; a fixing and supporting means for fixing and supporting a magnet on the axial side of the cylindrical portion opposite to the side where the cap is attached; a diameter expanding means for expanding the inner diameter of the cylindrical portion and for allowing the magnet to be attached and detached; characterized in that it comprises attachment.

2. The diameter expanding means includes a notch provided on at least the attachment side of the cap of the side surface of the cylindrical portion.

2. The attachment of claim 1.

3. The diameter expanding means is provided on a side surface of the cylindrical portion and includes a slit penetrating the cylindrical portion along the axial direction.

2. The attachment of claim 1.

4. The fixed support means is a first protrusion provided on an inner surface of the cylindrical portion and protruding radially inward from the cylindrical portion, the first protrusion being capable of supporting a main surface of the magnet opposite to the attachment side of the cap; a second protruding portion that is provided on the inner surface closer to the cap mounting side than the first protruding portion and protrudes radially inward, the second protruding portion enabling the magnet to climb over when the magnet is mounted and enabling the main surface of the magnet on the cap mounting side to be fixed; characterized in that it comprises 2. The attachment of claim 1.

5. The present invention is characterized in that the cap further comprises a diameter reducing means that applies a tightening force toward the radially inward direction of the cylindrical portion to the cylindrical portion by interfering with the inner surface of the bottom of the cap when the cap is attached.

2. The attachment of claim 1.

6. the cylindrical portion further includes a flange protruding radially outward from the cylindrical portion on a side opposite to the side where the cap is attached, the diameter reducing means is provided upright from the flange along the axial direction of the cylindrical portion, and includes an inclined surface that faces the inner surface of the bottom of the cap when the cap is attached.

6. The attachment according to claim 5.

7. the cylindrical portion further includes a threaded portion onto which the cap can be threaded; The diameter expanding means is provided in a region of the cylindrical portion that is 270° or more and less than 360° clockwise from the threading start end of the threaded portion when viewed from the attachment side of the cap.

7. An attachment according to any one of claims 1 to 6.

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