Opening / closing body and magnetic-matter removing apparatus

Abstract

To provide an opening / closing body capable of stably securing a high sealing degree in a closed state of an opening and easily opening the opening in maintenance or the like, and a magnetic substance removing device using the opening / closing body.SOLUTION: The body 1 is provided with an opening 12 and has a lid plate 2 for closing the opening 12. A lid plate side magnet part 21 is provided on the periphery of the lid plate 2, and a body side magnet part 11 is provided on the body 1 facing the lid plate side magnet part 21. The magnetic poles of the lid plate side magnet part 21 and the magnetic poles of the main body side magnet part 11 facing each other when the lid plate 2 is attached at a predetermined position are arranged so as to be different from each other, and the lid plate 2 can be attached to the main body 1 by firmly magnetically attracting between the different magnetic poles. Further, the main body side magnet portion 11 and the lid plate side magnet portion 21 are arranged such that different magnetic poles are aligned, and when the lid plate 2 is shifted, the same magnetic poles face each other to generate a repulsive force, so that the lid plate 2 can be easily removed.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an opening / closing body that closes an opening with an openable / closable cover plate, and also to a magnetic substance removing device that uses such an opening / closing body. [Background technology]

[0002] When manufacturing products using materials such as powders, granules, liquids, or gases, foreign matter such as metals may be mixed in the materials, which can cause malfunctions in the manufacturing equipment or be mixed into the products, resulting in defective products.For this reason, magnetic material removal devices are used to remove magnetic material such as metals from materials using magnetic force.

[0003] Figure 10 is a front view showing an example of a conventional magnetic material removal device. In the figure, 1 is the main body, 2 is the cover plate, 3 is the inlet, 4 is the outlet, 5 is the magnet body, and 51 is the bolt. Inside the main body 1, multiple magnet bodies 5 with strong magnetic force are provided. When material is fed or transported through the inlet 3, the material comes into contact with the magnet bodies 5, and if magnetic material is mixed in, the magnetic material is magnetically attracted to the magnet bodies 5 and removed. The material from which the magnetic material has been removed by the magnet bodies 5 is discharged from the outlet 4.

[0004] The magnetic materials attracted and removed in this way accumulate on the surface of the magnetic body 5. If the amount of magnetically attracted magnetic materials increases, the magnetic force acting on newly arriving magnetic materials will decrease, making it impossible to sufficiently attract the magnetic materials, or magnetic materials that have been magnetically attracted will fall off and become mixed in again with the material, causing problems. For this reason, it is necessary to clean and remove the magnetic materials that have accumulated on the surface of the magnetic body 5 at an appropriate time.

[0005] To perform cleaning, the magnet body 5 housed inside must be removed and a cleaning tool must be inserted inside, and an opening for this purpose is provided in the main body 1, with the cover plate 2 attached so as to be able to open and close freely to cover the opening. Although the cover plate 2 can be opened and closed freely for maintenance such as cleaning, it is necessary to ensure a seal so that materials do not leak from the gap between the main body 1 and the cover plate 2 during operation. For this reason, for example, in the example shown in Figure 10, the cover plate 2 is fastened to the main body 1 with multiple bolts 51.

[0006] However, tightening the bolts 51 requires time, and increasing the number of bolts 51 required to improve the level of sealing makes attaching and removing the cover plate 2 a very time-consuming process. Furthermore, the level of sealing can change due to human error, such as forgetting to tighten or tightening force, or the tightening order, which can sometimes lead to material leakage. When such material leakage occurs, the bolts 51 are tightened again to increase the tightening force, which can damage the bolts 51 or cause metal powder from the damage to become a foreign object mixed into the material.

[0007] In addition to the bolt fastening method described above, several methods have been adopted for fastening the cover plate 2. For example, Patent Document 1 describes a method using a sealing handle. The sealing handle is designed to hold the cover plate down using the rotational friction of the handle, making it easy to operate. However, with frequent use, wear occurs due to the frictional rotation, and the level of sealing cannot be ensured without readjustment. For this reason, adjustment becomes difficult when used frequently, so it can only be applied to relatively small covers. Furthermore, since the cover plate surface is held down by rotational friction, metal friction naturally generates powder, which becomes a source of foreign matter.

[0008] Other methods include using a buckle, as described in Patent Document 2, or a toggle clamp. These methods use a rotating shaft to directly press down on the cover plate, making the process relatively simple. However, if the pressing shaft loosens due to rotation, readjustment is required, making them unsuitable for installing multiple units. Therefore, they cannot be used in large numbers like bolts, and there is a limit to the force with which they can press down on the cover plate, making it more difficult to ensure a tight seal than bolts.

[0009] As described above, the conventional method of attaching a cover plate uses many bolts to ensure uniform adhesion of the cover plate and maximize airtightness. However, using a large number of bolts requires a long time to tighten and remove, hindering maintenance work. Furthermore, bolts removed during maintenance work sometimes get lost, which requires time to prepare replacement bolts, resulting in extended production downtime.

[0010] On the other hand, opening / closing devices that close an opening with an openable cover plate are not limited to the magnetic material removal device described above, but are naturally used in a variety of applications. Some of these applications use magnets. For example, the magnetic attraction force is sometimes used to keep furniture doors closed. In such applications, magnets with a weak attraction force are used so that ordinary users do not have to strain their fingers when opening the door. Another example is the magnetic attraction force used in refrigerator doors. In this case, too, the magnetic attraction force is weak because ordinary users must open the refrigerator door, and the drawback of weak magnetic attraction is compensated for by adjusting the thickness of the silicone rubber on the door.

[0011] As described above, in devices used in manufacturing lines such as the magnetic material removal device, or in opening / closing bodies for closing inspection hatches that are normally closed, a high degree of sealing is achieved when the opening is closed, but the opening cannot be easily opened during maintenance work, etc. Also, while some opening / closing doors that are intended to be opened use magnets, the current situation is that a high degree of sealing is not achieved by magnetic force alone. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Patent No. 4953042 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-347685 Summary of the Invention [Problem to be solved by the invention]

[0013] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide an opening / closing body that stably ensures a high degree of sealing when the opening is closed, and that can easily open the opening during maintenance, etc., and a magnetic material removal device that uses such an opening / closing body. [Means for solving the problem]

[0014] The invention described in claim 1 of the present application is an opening / closing body that closes an opening with an openable cover plate, wherein the peripheral portion of one side of the cover plate faces the peripheral surface surrounding the opening, and a magnet portion is provided on the opposing peripheral portion of the cover plate and on the peripheral surface surrounding the opening, and when the cover plate is attached to a predetermined position, the magnetic poles of the magnet portion on the opposing cover plate side and the magnetic poles of the magnet portion on the peripheral surface side of the opening are arranged so that they are different from each other, and the respective magnet portions are arranged so that their different magnetic poles are lined up.

[0015] The invention described in claim 2 of the present application is an opening / closing body characterized in that, in addition to the configuration of the invention described in claim 1 of the present application, a shifting means is further provided for shifting the cover plate along the peripheral surface of the opening.

[0016] The invention described in claim 3 of the present application is a magnetic material removal device characterized by having a built-in magnet body for attracting and removing magnetic materials by magnetic force, and having an opening / closing body described in claim 1 or claim 2, which is provided with an inlet, an outlet, and an opening for maintenance, and which covers the opening with an openable / closable cover plate.

[0017] The invention described in claim 4 of the present application is a magnetic material removal device characterized in that the cover plate of the invention described in claim 3 of the present application has a hook portion at the left or right end and a rod-shaped portion extending in the vertical direction continuous with the hook portion, and a tube portion through which the rod-shaped portion is inserted is provided on the left or right peripheral surface of the opening, and the tube portion has an internal space through which the rod-shaped portion can move when the cover plate is shifted along the peripheral surface of the opening. [Effects of the Invention]

[0018] According to this invention, when the cover plate is attached in a predetermined position and the opening is closed, the magnetic poles of the magnets on the opposing cover plate and the magnets on the periphery of the opening are different, so they attract each other, causing strong magnetic attraction between the cover plate and the magnets, ensuring a high level of airtightness. Furthermore, the magnetic attraction provides uniform contact pressure, ensuring a stable and sufficient level of airtightness.

[0019] When removing the cover plate to open the opening, the opening can be opened by sliding the cover plate along the periphery of the opening. While a large force is required to separate the magnets that are attracting each other in the direction of the magnetic field lines, a relatively small force is required to move them in a direction roughly perpendicular to the magnetic field lines. Furthermore, by sliding the cover plate, the magnetic poles of the magnets on the cover plate side and the magnets on the periphery of the opening approach each other, generating a repulsive force. This allows the cover plate to be removed with little force to open the opening. Furthermore, since no parts other than the cover plate, such as bolts, are used, problems such as lost parts can be eliminated.

[0020] Furthermore, if a shifting means for shifting the cover plate is provided, the cover plate can be slid and removed more easily to open the opening.

[0021] Such an opening / closing body can be applied to a magnetic material removal device, and when closed, a high level of sealing can be stably ensured, while the opening can be easily opened during maintenance, etc., thereby improving work efficiency during maintenance.

[0022] The hook structure also prevents the cover from shifting vertically. The rod-shaped part connected to the hook can be inserted into the tube to absorb any shifting of the cover and function as a hinge. When the cover is removed, the opening can be opened by rotating the cover, allowing maintenance to be performed. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a configuration diagram showing a first embodiment of the present invention. [Figure 2] 2 is a plan view of the cover plate and the vicinity of the opening in the first embodiment of the present invention. FIG. [Figure 3] 3 is an enlarged cross-sectional view showing an example of a magnet section in the first embodiment of the present invention. FIG. [Figure 4] 5A to 5C are explanatory views of an example of an attachment / detachment operation of the cover plate in the first embodiment of the present invention. [Figure 5] 10 is a diagram (continued) illustrating an example of the operation of attaching and detaching the cover plate in the first embodiment of the present invention. FIG. [Figure 6] FIG. 10 is an explanatory diagram of a modified example of the first embodiment of the present invention. [Figure 7] FIG. 10 is a diagram (continued) illustrating a modified example of the first embodiment of the present invention. [Figure 8] FIG. 10 is an explanatory diagram of another modified example of the first embodiment of the present invention. [Figure 9] FIG. 10 is an explanatory diagram of a second embodiment of the present invention. [Figure 10] FIG. 1 is a front view showing an example of a conventional magnetic substance removing device. DETAILED DESCRIPTION OF THE INVENTION

[0024] Fig. 1 is a diagram showing a first embodiment of the present invention, Fig. 2 is a plan view of the vicinity of the cover plate and opening, and Fig. 3 is an enlarged cross-sectional view showing an example of a magnet unit. In the figures, 1 is a main body, 2 is a cover plate, 3 is an inlet, 4 is an outlet, 5 is a magnet body, 11 is a main body-side magnet unit, 12 is an opening, 13 is a tube unit, 14 is an opening handle, 15 is a guide unit, 21 is a cover plate-side magnet unit, 22 is a packing member, 23 is a hook unit, 24 is a rod-shaped unit, 25 is a handle, 31 is a grip unit, 32 is a shaft unit, and 33 is a contact unit. This example shows an example in which the opening / closing body of the present invention is applied to a magnetic material removal device.

[0025] The magnetic material removal device has a main body 1 with an inlet 3 at the top and a discharge outlet 4 at the bottom. Inside the main body 1, multiple magnet bodies 5 with strong magnetic force are also provided. When material is fed or transported through the inlet 3, the material comes into contact with the magnet bodies 5, and if magnetic material is mixed in, the magnetic material is magnetically attracted to the magnet bodies 5 and removed. The material from which the magnetic material has been removed by the magnet bodies 5 is discharged from the discharge outlet 4.

[0026] The magnetic material thus attracted and removed accumulates on the surface of the magnetic body 5. As the amount of magnetically attracted magnetic material increases, the magnetic force acting on newly arriving magnetic material decreases, making it impossible to sufficiently attract the magnetic material, or magnetic material that has been magnetically attracted may fall off and re-enter the material, resulting in problems. Therefore, the main body 1 is provided with an opening 12 for maintenance purposes, such as cleaning and removing magnetic material accumulated on the surface of the magnetic body 5 at an appropriate time. During maintenance, the input of material is stopped, and the magnetic material magnetically attracted to the surface of the internal magnetic body 5 is cleaned and removed through the opening 12 by suction or other means. Alternatively, the internal magnetic body 5 may be removed through the opening 12, the magnetic material magnetically attracted to the surface cleaned and removed, and then the magnetic body 5 may be set back into the main body 1 through the opening 12. Of course, cleaning the interior of the main body 1 can also be performed through this opening 12.

[0027] If the opening 12 is not closed while the device is in operation, the material will leak out through the opening 12, so the device has a cover plate 2 that closes the opening 12. The cover plate 2 is larger than the opening 12, and the peripheral portion of the surface of the cover plate 2 that faces the main body 1 faces the peripheral surface surrounding the opening 12 (the surface of the main body 1). When the device is in operation, the cover plate 2 may be subjected to air pressure due to contact and feeding of the material, so it must be firmly attached to the main body 1. For this reason, in the past, the cover plate 2 was attached to the main body 1 at the portion where the main body 1 and cover plate 2 face each other using a fastening means that is firmly attached but can also be removed, such as bolts.

[0028] In contrast, in the present invention, the cover plate 2 is magnetically attracted to the main body 1 using a magnetic force sufficient to firmly attach the cover plate 2 to the main body 1. To achieve this, a cover-side magnet portion 21 is provided around the periphery of the surface of the cover plate 2 facing the main body 1, and a body-side magnet portion 11 is provided around the periphery of the opening 12 of the main body 1 facing the cover plate 2. When the opening 12 is closed by the cover plate 2, the body-side magnet portion 11 and the cover-side magnet portion 21 are magnetically attracted to each other. This magnetic attraction attaches the cover plate 2 to the main body 1 and closes the opening 12. In this embodiment, as shown in FIG. 2 as an example, the body-side magnet portion 11 is provided around the entire periphery of the opening 12, and the cover-side magnet portion 21 is also provided around the entire periphery of the cover plate 2. In this example, the body-side magnet portion 11 and the cover-side magnet portion 21 can be, for example, sheet magnets or plate-shaped magnets with multiple north and south poles.

[0029] A high level of airtightness is required because the device must be able to withstand the contact and air pressure caused by material flow during operation and prevent leakage of these factors. For example, if the magnetic attraction force is weak, airtightness cannot be ensured, so the cover plate 2 must be firmly attached to the main body 1 using a strong magnetic attraction force. Therefore, the main body side magnet portion 11 and the cover plate side magnet portion 21 must have a magnetic attraction force sufficient to firmly attach the cover plate 2 to the main body 1 with a high level of airtightness. This magnetic attraction force allows the cover plate 2 to be firmly attached to the main body 1. For example, even if the magnetic attraction force is weak locally, it is sufficient to ensure a wide magnetic attraction area and achieve sufficient magnetic attraction overall.

[0030] In the present invention, the magnetic poles arranged on the cover plate-side magnet portion 21 and the corresponding magnetic poles arranged on the body-side magnet portion 11 are arranged so that different magnetic poles are aligned side by side. That is, an S pole is arranged adjacent to an N pole, and an N pole is arranged adjacent to an S pole. In this embodiment, as shown in an example in FIG. 2, the body-side magnet portion 11 provided around the entire periphery of the opening 12 has N poles and S poles arranged alternately in the left-right direction. The cover plate-side magnet portion 21 provided around the entire periphery of the cover plate 2 also has N poles and S poles arranged alternately in the left-right direction, corresponding to the N poles and S poles arranged on the body-side magnet portion 11.

[0031] In this example, the main body magnet section 11 and the cover plate magnet section 21 have a large number of magnets with short pole lengths arranged in the upper and lower sections. On the left and right sides, several magnets with long pole lengths in the vertical direction, for example, two to four magnets, are arranged. For example, when the magnetic pole spacing is 5 mm, an overall magnetic flux density of approximately 0.12 to 0.2 T (1200 to 2000 G (gauss)) is obtained. The magnitude of the magnetic flux density can be determined at the time of design depending on the size, weight, and airtightness of the cover plate 2. Similarly, the magnetic pole spacing and number of magnetic poles can also be determined at the time of design.

[0032] When the cover plate 2 is attached to the specified position, the magnetic poles of the cover-side magnet portion 21 and the body-side magnet portion 11 are arranged so that the opposing magnetic poles are different from each other, as shown in FIG. 3 . That is, the magnetic poles of the cover-side magnet portion 21 and the body-side magnet portion 11 are arranged so that the north pole faces the south pole and the south pole faces the north pole, respectively. As a result, the north pole faces the south pole and the south pole faces the north pole of the cover-side magnet portion 21 and the body-side magnet portion 11, attracting each other and generating a strong magnetic attraction force. In this example, the strong magnetic attraction force allows the cover plate 2 to be attached to the body 1 uniformly around the opening 12, achieving a high level of sealing overall. This does not result in artificial variations, such as those caused by bolt tightening.

[0033] Furthermore, even if the installation position of the cover plate 2 is slightly misaligned, the misalignment is corrected by the mutual attraction of different magnetic poles, allowing the cover plate 2 to be installed in approximately the desired position. If the installation position of the cover plate 2 is slightly misaligned, for example, the north pole will move away from the south pole, which would normally be magnetically attracted to each other, and approach the adjacent north pole. Since north and north poles repel each other, it will be pushed toward the south pole. The same is true for the south pole; if the north pole moves away from the north pole, which would normally be magnetically attracted to each other, and approaches the adjacent south pole, the south poles will repel each other and be pushed toward the adjacent north pole. This repulsive force between like poles and the magnetic attractive force between different magnetic poles as described above corrects any misalignment of the cover plate 2 within the magnetic pole spacing, allowing the cover plate 2 to be installed in approximately the desired position. In this example, the north and south poles are arranged alternately in the left-right direction, so the misalignment in the left-right direction is corrected, allowing the cover plate 2 to be installed in the desired position in the left-right direction.

[0034] Sheet magnets and plate-shaped magnets, which are examples of the body-side magnet portion 11 and the cover-side magnet portion 21, have been used in the past to magnetically attract the lid plate by providing sheet-shaped magnets with different magnetic poles on the opening side and the cover plate side. However, these magnets were only used to prevent the lid plate from opening or to allow the lid plate to be opened by peeling it off against the magnetic force, and were not able to seal the interior of the body. In this embodiment, by providing a large attraction area, such as around the opening 12, a sufficient level of sealing can be achieved even with sheet magnets with weak magnetic force. Note that when the lid plate 2 is magnetically attracted to a sufficient level of sealing, it is not easy to manually remove the lid plate 2 by peeling the body-side magnet portion 11 and the cover-side magnet portion 21 in the direction of the magnetic field lines. As described below, the lid plate 2 must be removed by shifting it in a direction approximately perpendicular to the direction of the magnetic field lines.

[0035] In this embodiment, the packing member 22 is located inside the cover-side magnet portion 21 provided around the periphery of the cover plate 2. The packing member 22 is made of an elastic material, and when the cover plate 2 is attached, it is sandwiched and compressed between the cover plate 2 and the main body 1 around the opening 12 of the main body 1, as shown in FIG. 3 . This increases the airtightness of the device when the cover plate 2 is closed. Note that, depending on the elasticity and thickness of the packing member 22, the main body-side magnet portion 11 and the cover-side magnet portion 21 may not come into contact simply by attaching the cover plate 2. However, by slightly pushing the cover plate 2 against the elastic force of the packing member 22, the main body-side magnet portion 11 and the cover-side magnet portion 21 approach each other and make contact, thereby generating a stronger magnetic force. This further compresses the packing member 22, increasing the tightness of contact between the packing member 22 and the main body 1 and increasing the airtightness of the device.

[0036] Of course, this packing member 22 may be provided inside the main body-side magnet portion 11, or may be provided on both the main body 1 side and the cover plate 2 side so that the packing members are pressed against each other. Also, if the cover plate-side magnet portion 21 or the main body-side magnet portion 11 have cushioning properties, they may be configured to fulfill the function of the packing member 22. Of course, if the contact surfaces of the cover plate-side magnet portion 21 and the main body-side magnet portion 11 are sufficiently smooth, or if sufficient sealing can be ensured, the packing member 22 may not be provided.

[0037] The alternating arrangement of magnetic poles described above is effective when removing the cover plate 2 from the main body 1 for maintenance, etc. As described above, the magnetic attraction between the main body-side magnet portion 11 and the cover plate-side magnet portion 21 firmly attaches the cover plate 2 to the main body 1 with a high degree of sealing. Therefore, pulling the cover plate 2 toward the front to remove it from the main body 1 requires a strong force to overcome the strong magnetic attraction, making it difficult to remove the cover plate 2 by pulling it away. Generally, it is not easy to separate the magnets in the direction of the magnetic field lines when their north and south poles are attracted to each other. In contrast, shifting the magnets in a direction approximately perpendicular to the magnetic field lines requires less force than separating them in the direction of the magnetic field lines. In other words, shifting the main body 1 and the cover plate 2 in the planar direction (left-right or up-down in the figure) requires less force than separating them in the direction of the magnetic field lines (toward the front).

[0038] For example, if the north pole of the cover-side magnet portion 21 and the corresponding south pole of the main body-side magnet portion 11 are attracted to each other, shifting the cover plate 2 left or right will reduce the magnetic attraction between the attracted north and south poles. At the same time, the north pole of the cover-side magnet portion 21 will approach the north pole adjacent to the south pole of the main body-side magnet portion 11, generating a repulsive force between the north poles. Similarly, the south pole of the main body-side magnet portion 11 will approach the south pole adjacent to the north pole of the cover-side magnet portion 21, generating a repulsive force between the south poles. In this way, shifting the cover plate 2 reduces the magnetic attraction and increases the repulsive force, causing the cover plate 2 to naturally move in the opening direction, allowing it to be removed with little force.

[0039] As described above, in the present invention, the magnetic attraction force allows the cover plate 2 to be firmly and stably attached to the designated position on the main body 1, ensuring a level of airtightness sufficient for use on a production line. Furthermore, the magnetic attraction ensures uniform contact pressure between the cover plate and the main body, ensuring a stable and sufficient level of airtightness. When the cover plate 2 needs to be removed for maintenance or other purposes, it can be easily removed by simply shifting the cover plate 2 with little force. This improves the efficiency of maintenance.

[0040] Unlike conventional bolt fastening methods, which require time-consuming work such as installing and removing bolts one by one, this method eliminates the need for separate parts, and there are no problems such as losing parts when removing the cover plate 2. Of course, the attachment strength when the cover plate 2 is attached is comparable to other fastening methods, and the uniform magnetic attraction force eliminates the variations that occur with bolt fastening, ensuring a stable level of airtightness. Furthermore, there is no need to adjust the attachment strength, which is necessary with some fastening methods, and there is no risk of metal powder being mixed into the material due to damage, etc.

[0041] The operation to shift the cover plate 2 may be performed manually by an operator, but in this example, a shifting means for shifting the cover plate 2 may be provided. In this example, an opening handle 14 is provided on the main body 1 as the shifting means. This opening handle 14 has a grip portion 31, a shaft portion 32, and an abutment portion 33, and by holding the grip portion 31 and rotating it about the shaft portion 32, the abutment portion 33 also rotates. As the handle rotates, the abutment portion 33 abuts against the side of the cover plate 2, and by further rotating it, the cover plate 2 can be shifted. Note that various known structures other than the opening handle 14 can be used as the structure for shifting the cover plate 2, and such a structure need not be provided.

[0042] In this embodiment, a hook portion 23 protrudes from the left or right end of the cover plate 2, and a rod-shaped portion 24 extending in the vertical direction continues from the hook portion 23. Furthermore, a tube portion 13 extending in the vertical direction is provided at the left or right end of the opening 2 in the main body 1, and the rod-shaped portion 24 of the cover plate 2 is inserted into this tube portion 13. In the example shown in FIGS. 1 and 2, the tube portions 13 are provided at the top and bottom of the main body 1, sandwiching the opening handle 14 on the left side. Two rod-shaped portions 24 corresponding to the tube portions 13 extend downward from the hook portion 23 protruding from the main body of the cover plate 2. Note that the cover plate 2 shown in FIG. 2(A) shows the surface facing the main body 1, and since the left and right sides are reversed, the hook portion 23 and rod-shaped portion 24 are provided on the right side in FIG. 2(A).

[0043] The hook portion 23 of the cover plate 2 abuts against and catches the upper end of the pipe portion 13 of the main body 1, preventing the cover plate 2 from falling off. Furthermore, the hook portion 23 and rod-shaped portion 24 of the cover plate 2 and the pipe portion 13 of the main body 1 form a hinge portion. When the cover plate 2 is removed from the main body 1, the cover plate 2 can be rotated around this hinge portion as a rotation center to open the opening 12 of the main body 1. This allows the opening 12 to be opened with little force by simply rotating the cover plate 2, which is a heavy object, without having to lift or carry it, and also prevents damage caused by the cover plate 2 falling or injury to workers. Of course, the cover plate 2 can also be removed from the main body 1 by lifting the cover plate 2 upward and pulling the rod-shaped portion 24 off the pipe portion 13. In this example, two sets of hinge portions, each consisting of the hook portion 23, rod-shaped portion 24, and pipe 13, are provided. However, only one set or three or more sets may be provided.

[0044] In this example, in order to facilitate the operation of rotating the cover plate 2, a handle 25 is provided near the end of the cover plate 2 opposite to the side where the hook portion 23 and the rod-shaped portion 24 are provided. The presence or absence of the handle 25 and its shape are optional.

[0045] As described above, the hinge portion is made up of the hook portion 23, the rod-shaped portion 24, and the pipe 13, but operations such as sliding the cover plate 2 sideways are not possible with ordinary hinges. Therefore, in this embodiment, the pipe portion 13 provided on the main body 1 has an internal space that allows at least the rod-shaped portion 24 of the cover plate 2 to move left and right. Furthermore, the distance between the end of the cover plate 2 where the rod-shaped portion 24 is located and the rod-shaped portion 24 should be large enough to allow the cover plate 2 to be moved when removing the cover plate 2. With this configuration, the cover plate 2 can be easily removed from the main body 1 by sliding the cover plate 2 sideways relative to the main body 1 and then rotating it.

[0046] In this example, when the cover plate 2 is removed, it is shifted to the right in the drawing, and the internal space of the tube part 13 has at least enough space to allow the inserted rod-shaped part 24 to move to the right by the amount of shift when removing the cover plate 2. For the cover plate 2 as well, a gap at least equal to the amount of shift when removing the cover plate 2 is provided between the end face of the cover plate 2 and the rod-shaped part 24.

[0047] The internal space of the tube portion 13 requires not only the space through which the rod portion 24 is inserted as described above, but also the space through which the rod portion 24 can move when the cover plate 2 is shifted. The amount of shift required to remove the cover plate 2 is determined by the distance from the state in which the opposite magnetic poles attract each other to the state in which adjacent identical magnetic poles face each other and repel each other. In the initial state of shifting the cover plate 2, the force of attraction between the opposite magnetic poles is still strong, so a certain amount of shifting is necessary. Therefore, the cover plate 2 is shifted within a range of approximately 1 / 3 to 1 / 2 to 1 to 4 / 3 of the width of the magnetic poles or the distance between the centers of the magnetic poles. If the shift exceeds this range, the adjacent opposite magnetic poles will be closer, and the magnetic attraction force will again become stronger. Therefore, when removing the cover plate 2, it is recommended to shift it within a range of approximately 1 / 3 or 1 / 2 to 1 or 4 / 3 of the width of the magnetic poles or the distance between the centers of the magnetic poles. It is also advisable to ensure that the internal space of the tube portion 13 allows the rod-shaped portion 24 to move within this range. Furthermore, if this internal space is ensured, even if the cover plate 2 is shifted beyond the aforementioned range of movement, the rod-shaped portion 24 will abut against the wall of the tube portion 13 and will not be able to move, thereby limiting the movement of the cover plate 2. This means that when attaching the cover plate 2, it can be attached to the main body 1 with an error of approximately 1 / 3 or 1 / 2 to 1 or 4 / 3 of the width of the magnetic poles or the distance between the centers of the magnetic poles, and thereafter the cover plate 2 can be attached in approximately the desired position by using the repulsive force between like poles and the magnetic attractive force between opposite magnetic poles, or by initially shifting the cover plate 2 slightly.

[0048] To explain a specific example based on the illustrated example, when the cover plate 2 is attached in a predetermined position, the rod-shaped portion 24 is in contact with or close to the wall of the tube portion 13 on the left side in the figure. For example, if the magnetic pole width or center-to-center distance of the magnetic poles is 5 mm, then when removing the cover plate 2, it should be moved to the right by approximately 1.7 mm or 2.5 mm to 5 mm. Therefore, the internal space of the tube portion 13 should have enough space to allow the rod-shaped portion 24 to move to the right by approximately 1.7 mm or 2.5 mm to 5 mm from the insertion position. Furthermore, immediately after removing the cover plate 2, if the rod-shaped portion 24 is in contact with the wall of the tube portion 13 on the right side in the figure, further movement of the cover plate 2 can be limited. Of course, these numerical values ​​are merely examples and can be determined at the time of design based on various conditions, such as the magnet arrangement. The left-right direction can also be determined based on the design, such as whether the door is opened to the right or left and which direction the cover plate 2 should be moved.

[0049] As mentioned above, the internal space of the pipe 13 is large enough to allow the rod-shaped portion 24 to move, but this large internal space allows the inserted rod-shaped portion 24 some freedom of movement within the pipe 13, which causes the door edge side (the side opposite the rod-shaped portion 24) of the cover plate 2 to tend to sag due to its own weight. Therefore, when the removed cover plate 2 is rotated and attached to the main body 1, there is a concern that the cover plate 2 may abut against the main body 1 at a slight angle. In order to correct this sagging on the door edge side, a guide portion 15 is provided in this example.

[0050] As shown in Figure 1(B), this guide portion 15 is a rod- or plate-shaped member whose upper surface slopes downward as it moves away from the main body 1 in the forward direction. When attaching the cover plate 2 to the main body 1, the cover plate 2 is rotated closer to the main body 1, and the hanging edge of the cover plate 2 abuts against the upper surface of the end of the guide portion 15. When the cover plate 2 is further rotated closer to the main body 1, the edge side of the cover plate 2 is lifted in accordance with the slope of the upper surface of the guide portion 15. When the cover plate 2 finally abuts against the main body 1, the sagging edge side of the cover plate 2 is corrected, and the vertical attachment position of the cover plate 2 is set to the specified position.

[0051] Furthermore, when attaching the cover plate 2 to the main body 1, there is a concern that the attachment position may be misaligned by the amount of lateral movement when removing it due to the large internal space of the tube portion 13. However, as described above, the same poles of the main body side magnet portion 11 and the cover plate side magnet portion 21 repel each other, and the opposite magnetic poles attract each other, so that the misalignment in the left-right direction is corrected.

[0052] When attaching the cover plate 2 to the main body 1, no force is required by the worker to adjust the attachment position, and the cover plate 2 can be easily attached to approximately the desired position. Furthermore, because the cover plate 2 is attached by magnetic force, it is attached to the main body 1 with approximately the desired force and with a uniform force. There is no need for the work of applying pressure to the cover plate 2 against the main body 1 as with conventional bolt fastening, and there is no variation in the tightening force or the need for retightening.

[0053] With this configuration, even if vibration or external pressure to shift the cover plate 2 is applied, for example, a downward force will prevent the cover plate 2 from shifting due to the hook portion 23 or further the guide portion 15. Also, even if an upward force is applied, for example, the cover plate 2 will not fall unless the rod-shaped portion 24 comes out of the tube portion 13. Furthermore, if a force is applied in the left-right direction, for example, the rod-shaped portion 24 will come into contact inside the tube portion 13 and the cover plate 2 will not shift if the force is in the opposite direction to the removal direction. In the worst case scenario, there is a concern that the cover plate 2 may come off if a force is applied in the direction of removal of the cover plate 2, but even in this case the hook portion 23 is caught on the upper part of the tube portion 13, preventing the risk of it falling.

[0054] To deal with unexpected removal of the cover plate 2 due to such lateral forces, a structure to prevent lateral displacement may be added to either or both of the left and right ends of the cover plate 2. For example, one possible structure is that when the cover plate 2 is attached, a protrusion on one side fits into a recess on the other side, and when the cover plate 2 is removed, the protrusion retracts to release the engagement. Alternatively, various known structures can be applied, such as a crescent-like rotation for engagement and release.

[0055] 4 and 5 are explanatory diagrams illustrating an example of the operation of attaching and detaching the cover plate in the first embodiment of the present invention. As described above, when removing the attached cover plate 2, the cover plate 2 can be removed from the main body 1 by shifting the cover plate 2 relative to the main body 1. First, as shown in FIG. 4(A), the release handle 14 is rotated and the cover plate 2 is pushed aside, thereby shifting the cover plate 2 in the surface direction, in this example, to the right in the figure. When the cover plate 2 is attached, as shown in FIG. 3, the north and south poles are strongly magnetically attracted to each other. However, by shifting the cover plate 2 in the surface direction relative to the main body 1, the arrangement of the magnetic poles shown in FIG. 3(B) shifts as shown in FIG. 4(B). Then, by shifting the cover plate 2, the opposing area of ​​the magnetically attracted north and south poles decreases, thereby reducing the magnetic attraction force. Furthermore, because the north and south poles are arranged adjacent to each other, shifting the cover plate 2 brings the north pole of the main body-side magnet section 11 closer to the north pole on the cover plate-side magnet section 21, and the south pole of the main body-side magnet section 11 closer to the south pole on the cover plate-side magnet section 21, thereby increasing the repulsive force. In this way, shifting the cover plate 2 reduces the attractive force between different magnetic poles and increases the repulsive force between the same magnetic poles, making it relatively easy to remove the cover plate 2. The cover plate 2 can be removed by shifting it by about half the distance between the magnetic poles arranged in the main body-side magnet section 11 and the cover plate-side magnet section 21.

[0056] Even if the cover plate 2 comes off the main body 1, the hook portion 23 of the cover plate 2 is caught on the upper part of the tube portion 13 of the main body 1, so it will not fall. Then, as shown in FIG. 5(A), by rotating the cover plate 2 around the hinge portion formed by the rod-shaped portion 24 and the tube portion 13 as an axis, the opening 12 of the main body 1 will be exposed. In this state, maintenance of the inside of the main body 1 can be performed. Magnetic substances mixed in with the materials are magnetically attracted to the magnet body 5 contained inside the main body 1, and these can be cleaned and removed. Of course, cleaning and maintenance of the inside of the main body 1 can also be performed.

[0057] When the maintenance work is completed and the cover plate 2 is to be attached to the main body 1, the opening handle 14 is rotated to its original position so that the abutment portion 33 of the opening handle 14 does not abut the cover plate 2. Then, as shown in FIG. 5(B), the cover plate 2 is rotated around the hinge portion formed by the rod portion 24 and the tube portion 13 as an axis, and the cover plate 2 is brought close to the installation position on the main body 1. If the edge of the cover plate 2 is drooping, rotating the cover plate 2 toward the main body 1 will cause the edge of the drooping cover plate 2 to abut against the upper surface of the end of the guide portion 15. As the cover plate 2 is further rotated closer to the main body 1, the edge of the cover plate 2 is lifted in accordance with the inclination of the upper surface of the guide portion 15, and when the cover plate 2 finally abuts against the main body 1, the drooping of the edge of the cover plate 2 is corrected. The guide portion 15, the hook portion 23 of the cover plate 2, and the upper portion of the pipe 13 of the main body 1 are positioned vertically by abutment therebetween.

[0058] When the cover plate 2 abuts against the main body 1, the cover-side magnet portion 21 and the main body-side magnet portion 11 face each other. The north pole of the main body-side magnet portion 11 then attracts the south pole of the cover-side magnet portion 21, and the south pole of the main body-side magnet portion 11 attracts the north pole of the cover-side magnet portion 21. In this example, because different magnetic poles are arranged in the left-right direction, even if the same poles face each other, they are attracted to the adjacent different magnetic poles, and the cover plate 2 is attached in approximately the predetermined position in the left-right direction. For example, Figure 4(B) shows the relationship between the magnetic poles of the cover-side magnet portion 21 and the main body-side magnet portion 11 when the cover plate 2 is shifted by half the width of the magnetic poles. If the cover plate 2 faces the main body 1 in this state when the cover plate 2 is attached, the north poles repel each other and the south poles attract each other, and the south poles attract each other, so the cover plate 2 is attached to the main body 1 in the predetermined position where the south poles face each other. Thereafter, if necessary, the cover plate 2 is pressed to compress the packing member 22, thereby increasing the degree of airtightness inside the main body 1.

[0059] When like poles face each other, different magnetic poles exist on the adjacent left and right sides, raising the question of which side will be attracted to which different magnetic pole. However, if the internal space of the tube portion 13 attached to the main body 1 is limited to a size corresponding to the amount of shifting of the cover plate 2 when it is removed, the different magnetic poles will attract each other, allowing the cover plate 2 to be attached in the desired position. For example, in this example, the cover plate 2 is removed by shifting it to the right in the figure. The internal space of the tube portion 13 is limited so that the shifting amount is approximately 1 / 3, 1 / 2, to 1 / 4 / 3 of the width of the magnetic poles or the distance between the centers of the magnetic poles. This allows the cover plate 2 to be attached to the main body 1 with an error of approximately 1 / 3, 1 / 2, to 1 / 4 / 3 of the width of the magnetic poles or the distance between the centers of the magnetic poles. If the cover plate 2 can be attached to the main body 1 with this error, the repulsive force between like poles and the magnetic attractive force between the different magnetic poles in the desired position will allow the cover plate 2 to be attached in approximately the desired position.

[0060] To be more specific, for example, if we consider the south pole of the cover plate-side magnet section 21 and the north pole of the body-side magnet section 11, which face each other when the cover plate 2 is attached in a predetermined position, the amount of shifting of the cover plate 2 when removing it is limited to the extent that the south pole adjacent to the right of the north pole of the body-side magnet section 11 faces the south pole of the cover plate-side magnet section 21. Also, when attaching the cover plate 2, the error when the cover plate 2 abuts against the body 1 is limited to the extent that the south pole adjacent to the right of the north pole of the body-side magnet section 11 faces the south pole of the cover plate-side magnet section 21, and the south pole of the cover plate-side magnet section 21 will not face or be attracted by the north pole two poles to the right of the north pole of the body-side magnet section 11. After that, the S pole adjacent to the right of the N pole of the main body side magnet part 11 and the S pole of the cover plate side magnet part 21 repel each other, and the N pole of a specified main body side magnet part 11 and the S pole of a specified cover plate side magnet part 21 attract each other, and the cover plate 2 is attached to the specified position.

[0061] If the amount of displacement of the cover plate 2 is approximately the width of the magnetic poles or the distance between the centers of the magnetic poles, it is possible that when the cover plate 2 is brought into contact with the main body 1, the same poles will be positioned facing each other, resulting in only a repulsive force. However, since the tube portion 13 restricts the movement of the rod-shaped portion 24 to the right in the figure, it will not be attracted to the different magnetic pole that is moving away from the designated position. Even in this case, the cover plate 2 can be attached to the designated position by moving it slightly to the left in the figure.

[0062] In this way, the cover plate 2 can be removed simply by shifting it, in this example by rotating the opening handle 14, and the cover plate 2 can be attached simply by bringing it close to the main body 1. This makes maintenance of the device extremely easy. Also, since no parts other than the cover plate, such as bolts, are used, problems such as lost parts can be eliminated.

[0063] 6 and 7 are explanatory diagrams of a modified example of the first embodiment of the present invention. In the above example, the body-side magnet portion 11 provided on the body 1 side and the cover-plate-side magnet portion 21 provided on the cover plate 2 side are provided around the entire circumference. However, if the cover plate 2 can be attached to the body 1 with a sufficient degree of sealing, these do not need to be provided around the entire circumference. For example, as shown in FIGS. 6(A) and 6(B), they can be provided intermittently. In this case, too, by arranging different magnetic poles adjacent to each other, the cover plate 2 can be easily removed.

[0064] Furthermore, if the cover plate 2 is removed by sliding it left and right, the main body magnet portion 11 and the cover plate magnet portion 21 may be provided only on the top and bottom portions, as shown in Figures 6(C) and 6(D). Alternatively, the main body magnet portion 11 and the cover plate magnet portion 21 may be provided only on the left and right portions, as shown in Figures 6(E) and 6(F). In this case, it is preferable to arrange adjacent different magnetic poles in the direction in which the cover plate 2 is moved when removed. In the example shown in Figure 7(A), the north pole and the south pole are arranged on the left and right.

[0065] Furthermore, in the example shown in Figures 7(A) and (B), the north and south poles are arranged so that different magnetic poles are aligned vertically on the left and right sides. This arrangement can prevent the cover plate 2 from shifting up and down. Also, the cover plate 2 can be attached in an approximately predetermined position in the vertical direction.

[0066] Similarly, in the examples shown in Figures 7(C) and (D), in the example where the main body side magnet portion 11 and the cover plate side magnet portion 21 are provided only on the left and right portions as shown in Figures 6(E) and (F), the north and south poles are arranged so that different magnetic poles are aligned vertically. This example may be applied, for example, to a configuration in which the cover plate 2 is removed by shifting it vertically. Furthermore, for example, as in the example shown in Figures 6(A) and (B), the main body side magnet portion 11 and the cover plate side magnet portion 21 may be provided intermittently on the top and bottom portions and on the left and right portions in the example shown in Figures 7(A) and (B).

[0067] Of course, the arrangement of the main body side magnet portion 11 and the cover plate side magnet portion 21 is not limited to these examples, and it goes without saying that various modifications are possible as long as the magnetic poles of the cover plate side magnet portion 21 and the magnetic poles of the main body side magnet portion 11 that face each other when the cover plate 2 is attached at a predetermined position are arranged so that they are different from each other, and the cover plate side magnet portion 21 and the main body side magnet portion 11 each have different magnetic poles lined up.

[0068] 8 is an explanatory diagram of another modified example of the first embodiment of the present invention. This example shows an example of a configuration in which the cover plate 2 is removed by sliding it to the left in the figure. An opening handle 14 for sliding the cover plate 2 is provided on the right side of the main body 1 in the figure, and the cover plate 2 can be easily moved to the left in the figure by rotating the opening handle 14 and pushing the cover plate 2 to the left in the figure with the abutment part 33.

[0069] In order to shift the cover plate 2 to the left in the figure, when the cover plate 2 is attached in a predetermined position, the rod-shaped portion 24 is positioned closer to the right side of the pipe portion 13 in the figure, with a space provided to the left of it in the pipe portion 13 of the main body 1. This space is just large enough for the rod-shaped portion 24 to move to the left within the pipe portion 13 when the cover plate 2 is shifted to the left in the figure. In addition, the movement of the rod-shaped portion 24 is restricted by the wall on the left side of the pipe portion 13, preventing the cover plate 2 from shifting too much. Note that in the above example, two sets of pipe 13, rod-shaped portion 24, and hook portion 23 were provided, but in this example, only one set is provided that extends vertically without being divided.

[0070] The other configurations are as described above, and it goes without saying that modifications of those can also be applied to this configuration example. Whether the cover plate 2 is to be slid to the left or right when removed can be decided at the time of design.

[0071] 9 is an explanatory diagram of a second embodiment of the present invention. In the figure, reference numeral 41 denotes a support portion. This second embodiment shows an example in which the hook portion 23 and rod-shaped portion 24 of the cover plate 2 and the tube portion 13 and opening handle 14 of the main body 1 in the first embodiment are not provided. Therefore, the cover plate 2 in this second embodiment is provided with a cover plate-side magnet portion 21 or a cover plate-side magnet portion 21 and a packing member 22.

[0072] The support portion 41 is a groove-shaped member provided in the main body 1. When the cover plate 2 is attached to a predetermined position, the lower part of the cover plate 2 abuts against the bottom of the groove-shaped portion, restricting the up and down movement of the cover plate 2. Of course, even without the support portion 41, the cover plate 2 is firmly attached to the main body 1 by the magnetic attraction force of the main body-side magnet portion 11 and the cover plate-side magnet portion 21, and this state is maintained. However, there is a concern that the cover plate 2 may shift and fall due to vibrations to the cover plate 2 or unexpected external pressure, and the support portion 41 supports the cover plate 2 to prevent it from falling.

[0073] Furthermore, when removing the cover plate 2 for maintenance work or the like, the cover plate 2 can be moved left and right along the support portions 41. The worker can move the cover plate 2 left and right while the weight of the cover plate 2 is resting on the support portions 41, which allows for efficient removal of the cover plate 2. Furthermore, the support portions 41 prevent the cover plate 2 from falling when moving the cover plate 2 left and right, allowing for safe operation. After moving the cover plate 2 left and right, the cover plate 2 can be lifted slightly upward to remove the lower end of the cover plate 2 from the support portions 41. Note that, similar to the first embodiment, by providing a means for moving the cover plate 2, such as the opening handle 14, and using this means to move the cover plate 2, the removal of the cover plate 2 can be performed even more easily.

[0074] When attaching the cover plate 2, the lower end of the cover plate 2 is fitted into the groove of the support portion 41. Using the support portion 41 in this way makes it easy to determine the vertical attachment position of the cover plate 2. As for the left-right attachment position, once it has been positioned to a certain extent, the different magnetic poles of the main body side magnet portion 11 and the cover plate side magnet portion 21 attract each other, and the cover plate 2 is attached in the specified position. For example, an abutment portion for the cover plate 2 may be provided on the left or right end of the support portion 41, and the cover plate 2 may be attached by abutting against this abutment portion, allowing the cover plate 2 to be attached in approximately the specified position.

[0075] In this second embodiment, in order to prevent the cover plate 2 from shifting laterally when attached, it is advisable to add a structure for preventing lateral shifting to either the left or right end of the cover plate 2, as in the first embodiment described above. In this case, various known structures can be applied to the structure for preventing lateral shifting. Also, a structure for preventing shifting may be added to the upper position of the cover plate 2. For either structure for preventing lateral shifting, a simple structure will suffice as long as it can prevent large positional shifts.

[0076] Furthermore, various modifications are possible for the main body side magnet section 11 and the cover plate side magnet section 21, as shown in Figures 6 and 7. The packing member 22 may also be provided inside the main body side magnet section 11, or on both the main body 1 side and the cover plate 2 side, or a configuration without the packing member 22 may also be possible.

[0077] In the above-described embodiments, examples have been shown in which the cover plate 2 is removed by sliding it left or right. However, this is not limiting, and the cover plate 2 may be removed by sliding it upward or downward, for example. For example, in the configuration of the main body-side magnet portion 11 and the cover plate-side magnet portion 21 shown in FIG. 7, sliding the cover plate 2 upward or downward reduces the magnetic attractive force and increases the repulsive force due to the different magnetic poles adjacent to the top and bottom of the main body-side magnet portion 11 and the cover plate-side magnet portion 21, allowing the cover plate 2 to be easily removed.

[0078] Furthermore, in each of the above-described embodiments, the magnetic body 5 is housed inside the main body 1, and during maintenance, the cover plate 2 is opened and the magnetic body 5 is cleaned through the opening 12. However, the present invention is not limited to this, and may be configured, for example, such that the magnetic body 5 is attached to the cover plate 2, and by removing the cover plate 2, the magnetic body 5 can be taken out together with the cover plate 2 from inside the main body 1, and then the magnetic body 5 can be cleaned.

[0079] Furthermore, in each of the above-described embodiments, an example of a configuration has been shown in which material is introduced from the top of the main body 1, and the material from which magnetic material has been removed by the magnet body 5 is discharged from the bottom. However, this is not limited to this, and the present invention can also be applied to a magnetic material removal device having a structure in which material is fed in the left-right direction and magnetic material is removed. In many cases, such magnetic material removal devices have an opening for maintenance at the top, and a cover plate to cover the opening. The present invention can be applied to this part. Needless to say, various modifications are possible without departing from the spirit and scope of the present invention.

[0080] Furthermore, the opening / closing body of the present invention is not limited to application to the magnetic material removal device described in the above-mentioned embodiments, but can be applied to various applications in which an opening is closed with an openable / closable cover plate. For example, the present invention can be applied to openings provided for maintenance work in industrial equipment other than magnetic material removal devices, or to inspection hatches provided in pipelines, and of course to various covers in consumer equipment. Furthermore, the present invention can be applied to various applications that have openings that need to be opened and closed, such as various doors, doors, and windows. [Explanation of symbols]

[0081] 1...main body, 2...cover plate, 3...feeding port, 4...discharge port, 5...magnet body, 11...magnet portion on main body side, 12...opening, 13...tube portion, 14...opening handle, 15...guide portion, 21...magnet portion on cover plate side, 22...packing member, 23...hook portion, 24...rod-shaped portion, 25...handle, 31...gripping portion, 32...shaft portion, 33...contact portion, 41...support portion, 51...bolt.

Claims

1. An opening / closing body that closes an opening with an openable cover plate, wherein the peripheral portion of one side of the cover plate faces the peripheral surface surrounding the opening, and a magnet portion is provided on each of the opposing peripheral portion of the cover plate and the peripheral surface surrounding the opening, and when the cover plate is attached to a predetermined position, the magnetic poles of the magnet portion on the cover plate side that face each other and the magnetic poles of the magnet portion on the peripheral surface side of the opening are arranged so that they are different from each other, and the respective magnet portions are arranged so that their different magnetic poles are lined up.

2. 2. The opening / closing body according to claim 1, further comprising a shifting means for shifting the cover plate along the peripheral surface of the opening.

3. A magnetic material removal device characterized by having an opening / closing body as described in claim 1 or claim 2, which has a built-in magnet body for attracting and removing magnetic materials by magnetic force, and is provided with an inlet, an outlet, and an opening for maintenance, and which closes the opening with an openable / closable cover plate.

4. The magnetic material removal device described in claim 3, characterized in that it has a hook portion at the left or right end of the cover plate and a rod-shaped portion extending in the vertical direction from the hook portion, and a tube portion through which the rod-shaped portion is inserted is provided on the left or right peripheral surface of the opening, and the tube portion has an internal space through which the rod-shaped portion can move when the cover plate is shifted along the peripheral surface of the opening.

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