JPS6239020Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a permanent magnet holding device suitable for use in lifting steel materials.

In this type of permanent magnet holding device, in order to obtain a strong magnetic attraction force, there is a first magnet in the magnetic circuit block.
A permanent magnet is fixed, and a second permanent magnet is rotatably housed in order to cooperate with the first permanent magnet to place the magnetic attraction surface of the magnetic circuit block in an energized and de-energized state.

Therefore, by operating the second permanent magnet to its excitation rotational position, the attraction surface can be strongly magnetized by the cooperation of both permanent magnets, and thereby a strong magnetic attraction force can be obtained. . Further, by operating the second permanent magnet to its non-excited rotational position, the permanent magnet and the first permanent magnet are magnetically short-circuited within the magnetic circuit block, thereby causing the strong magnetic field of the attracting surface. can be erased.

The first and second permanent magnets have respective magnetic flux guides so as to prevent leakage of magnetic flux from the attracting surface due to unbalance between the two magnets when the second permanent magnet is in a non-energized rotational position. The quantities are designed to be equal. However, in reality, due to variations in the material of each permanent magnet, manufacturing errors of each permanent magnet and magnetic circuit block, etc.
There is a difference in the amount of magnetic flux induction between the first and second permanent magnets, and due to this difference, leakage of magnetic flux may occur from the magnetic attraction surface even in the non-excited rotational position of the second permanent magnet. It is not possible to place the attraction surface in an almost completely non-excited state, that is, in a demagnetized state.

If the permanent magnet has a low coercive force, such as an alnico magnet, when the magnet is temporarily removed from the magnetic block and then reinserted into the predetermined position,
Utilizing the property that the amount of magnetic flux induction decreases according to the amount of the extracted portion, after partially extracting either the first or second permanent magnet with a large amount of magnetic flux induction, the magnetic circuit block is re-introduced. Adjustment work is being carried out to insert it into the specified position. This adjustment operation makes it possible to equalize the magnetic flux induction amounts of the first and second permanent magnets, and therefore,
When the second permanent magnet is operated to the non-excited rotational position, the magnetic attraction surface can be placed in a substantially completely demagnetized state.

However, in the above adjustment work, the decrease in the amount of magnetic flux induction caused by the removal of the permanent magnet cannot be compensated for except by magnetizing the permanent magnet again, and therefore this adjustment work is unlikely to fail. Unacceptable. Furthermore, it is difficult to determine the amount of extraction to obtain the desired reduction in the amount of magnetic flux induction. For this reason, there is a drawback that the adjustment work requires skill.

Further, when a permanent magnet having a high coercive force such as a ferrite magnet is used as the permanent magnet, the rotation operation of the second permanent magnet can be performed smoothly, but on the other hand, it is difficult to perform the above-mentioned adjustment work. Substantial adjustment of the amount of magnetic flux induction by a permanent magnet with high coercive force becomes impossible. Therefore, if there is a difference in the amount of magnetic flux induction between the first and second permanent magnets, it is not possible to put the magnetic attraction surface in an almost completely demagnetized state, and as a result, in reality, the above-mentioned permanent magnets It was not possible to use ferrite magnets.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a switchable permanent magnet holding device that can bring the magnetic attraction surface of a magnetic circuit block into an almost completely demagnetized state by a simple adjustment operation.

The present invention includes a magnetic circuit block comprising a pair of magnetic members each having a magnetic attraction surface and a non-magnetic member disposed between the magnetic members, and a first permanent magnetic circuit block housed and fixed within the magnetic circuit block. a second permanent magnet rotatably disposed within the magnetic circuit block and rotatably operated in cooperation with the first permanent magnet to place the magnetic attraction surface in an energized state and a de-energized state; , when the second permanent magnet is in the non-excited rotational position, both the magnetic members are magnetically connected to act as a bypass path for the magnetic flux generated due to the unbalance of the magnetic flux induction amount of the first and second permanent magnets. and a magnetic shorting member disposed in contact with the magnetic circuit block.

According to the present invention, by replacing the magnetic shorting member with one made of a material different in shape, size, or magnetic permeability, the permanent magnet can be removed without performing the conventional extraction operation of the permanent magnet. Regardless of the material of the permanent magnet, whether it is a permanent magnet with a low coercive force such as an alnico magnet or a permanent magnet with a high coercive force such as a ferrite magnet, the unbalance of the magnetic induction amount can be reduced by a magnetic short-circuiting member. By correcting this, it is possible to prevent the magnetic flux caused by the unbalance from appearing on the magnetic attraction surface, and to obtain a substantially complete demagnetization state on the magnetic attraction surface.

The features of the invention will become clearer from the following description of the illustrated embodiments.

As shown in FIG. 1, the permanent magnet holding device 10 according to the present invention includes a magnetic circuit block 12.
and first and second permanent magnets 14 and 16 housed within the magnetic block.

The magnetic circuit block 12 includes a pair of magnetic members 18
and a plate-shaped non-magnetic member 2 inserted between the magnetic member.
0, and the magnetic circuit block is formed with an upper lumen 22 and a lower lumen 24 that extend parallel to each other in the lateral direction of the non-magnetic member across the non-magnetic member 20 at the center of the magnetic circuit block. has been done.

In the illustrated example, the upper lumen 22 has a rectangular cross-sectional shape, in which the first permanent magnet 14 having a corresponding rectangular cross-sectional shape is arranged. The permanent magnet 14 is fixed within the bore 22 and has different magnetic pole faces (S, N) on both sides facing each magnetic member 18. Each cross-sectional shape of the inner cavity 22 and the fixed first permanent magnet 14 housed in the inner cavity can be made into a desired shape such as a circle. Further, as the first permanent magnet 14, a low coercive force permanent magnet such as an alnico magnet or a high coercive force permanent magnet such as a ferrite magnet can be used.

The lower lumen 24 has a circular cross-sectional shape and includes a second generally cylindrical permanent magnet 16 having an outer diameter slightly smaller than the inner diameter of the lumen 24.
is arranged so that it can rotate. This second permanent magnet 16 is a permanent magnet having a high coercive force, such as ferrite. The second permanent magnet 16 is magnetized in its diametrical direction, and has different magnetic pole faces (S, N) on mutually opposing diametrical outer peripheral surface portions. In the illustrated example, the permanent magnet 16 is slightly chamfered on both sides perpendicular to the radial direction of the magnetic pole surface, but a permanent magnet with a completely circular cross section is used without this chamfering. be able to. Further, as the second permanent magnet, a permanent magnet having a low coercive force such as an alnico magnet can be used, but since such a permanent magnet has a high magnetic flux density, it is difficult to design a dynamic magnetic circuit.
Requires high permeance. For this reason, the second
It is necessary to use a well-known permanent magnet 16' having an oval cross-sectional shape as a whole, as shown by the broken line in FIG. 1, as the permanent magnet.

The second permanent magnet 16 can be one whose total magnetic energy product is equal to that of the first permanent magnet 14, but in order to make the demagnetization adjustment described later easier, It is preferred to use permanent magnets having a total magnetic energy product slightly less than the total magnetic energy product of .

The second permanent magnet 16 or 16' can be moved between the non-excited rotational position shown in FIG. rotated between.
In the excitation rotational position, the magnetic pole of the second permanent magnet 16 or 16' is located on the same polar side as that of the first permanent magnet 14, so that both permanent magnets 14 and 16 , 16' pass through the magnetic attraction surface 18a formed at the lower end of each magnetic member. Therefore, the magnetic attraction surface 18a is strongly magnetized, and the material to be attracted, such as steel, can be reliably attracted and held on the attraction surface.

On the other hand, in the non-excited rotational position of the second permanent magnet 16 or 16', the magnetic pole of the second permanent magnet 16 or 16' is located on a side different from that of the first permanent magnet 14. As is well known, most of the magnetic flux of both permanent magnets 14 and 16, 16' constitutes a closed circuit within the magnetic circuit block 12. Therefore, the magnetic attraction force of the magnetic attraction surface 18a is significantly reduced.

However, when the second permanent magnet 16 or 16' is used as the second permanent magnet 16 or 16', the total magnetic energy product of which is smaller than that of the first permanent magnet 14, the induced magnetic flux of the first permanent magnet The amount of induced magnetic flux becomes larger than the amount of induced magnetic flux of the second permanent magnet. Therefore, a magnetic imbalance occurs between the first and second permanent magnets, and a portion of the magnetic flux passes through the attraction surface 18a, so that the second permanent magnet is in the non-excited rotational position. Despite this, the suction surface 18
It is not possible to place a in a completely de-energized state, that is, in a demagnetized state.

The above-described magnetic imbalance is not limited to the case where magnets with different total magnetic energy products are intentionally used as described above, but can also occur due to manufacturing errors of the above-mentioned permanent magnets and magnetic circuit blocks, etc.
In order to correct such magnetic imbalance, a magnetic shorting member 26 is provided in the magnetic circuit block 12.

The magnetic shorting member 26 is made of a magnetic material with high magnetic permeability, such as an iron plate, and is placed in contact with the tops of both magnetized members 18 . In the illustrated example, a cover 28 made of a non-magnetic material is disposed on the upper surface of the magnetic shorting member 26, and the cover 28 is integrally connected to the base portion 30a of the hanging fitting 30 and the bolt 32.
It is removably attached to the magnetic circuit block 12 via.

The magnetic shorting member 26 acts as a bypass path for a portion of the magnetic flux of the first permanent magnet adjacent thereto.

Therefore, by selecting the plate thickness, shape, material, etc. of the magnetic short-circuiting member 26, an excessive portion of the total magnetic energy product of the first permanent magnet can be short-circuited through the magnetic short-circuiting member 26. ,
As a result, in the non-excited rotational position of the second permanent magnet 16 or 16', part of the magnetic flux is transferred to the attraction surface 1.
8a, thereby allowing the attracting surface 18a to be in an almost completely demagnetized state.

As shown in phantom in FIG. 2, a magnetic shorting member 26 can be removably inserted into the bottom of the first lumen 22 from the side of the magnetic circuit block 12. Further, the total magnetic energy product of the first permanent magnet 14 is greater than the total magnetic energy product of the second permanent magnet 16 or 1.
If a magnetic imbalance occurs due to a large value of 6', in order to correct this, as shown by the solid line in FIG. A magnetic shorting member 26 that contacts both magnetic members 18 in the vicinity of the second permanent magnet can be removably disposed in the recess formed in the recess.

As mentioned above, it is desirable to use permanent magnets with the same total magnetic energy as the first and second permanent magnets, but in this case, it is virtually impossible to manufacture multiple permanent magnets with completely equal magnetic energy products. It is impossible, and the magnetic circuit block 12
It is not possible to predict which of the first and second permanent magnets will have a larger amount of magnetic flux induction due to manufacturing errors, etc. It is necessary to judge whether it should be placed. Therefore, as mentioned above, by using one permanent magnet in advance with a larger total magnetic energy than the other permanent magnet,
It is possible to eliminate the need for determining the selection of the placement location of the magnetic short-circuiting member described above.

Although a single permanent magnet holding device is shown in FIGS. 1 and 2, the present invention may also be applied to a double permanent magnet holding device 10 as shown in FIG. 3, for example. Structural parts which are similar to those shown in FIGS. 1 and 2 are provided with the same reference numerals. In the embodiment of FIG. 3, as is well known in the art, the right half of the intermediate magnetic member 18-1 is paired with the right magnetic member 18-2 joined to it via the non-magnetic member 20a. , the left side magnetic member 1 to which the left half of the intermediate magnetic member 18-1 is joined to this via the non-magnetic member 20b.
Pairs with 8-3. At the non-excited rotational position of each second permanent magnet 16, each magnetic member 18-1, 2,
A magnetic short-circuiting member 26 for placing the magnetic adsorption surface 18a of No. 3 in an almost completely demagnetized state is connected to the magnetic member 18.
-1, 2, and 3 and are removably arranged.

According to the present invention, as described above, by selecting the magnetic short-circuiting member, the magnetic attraction surface of the magnetic circuit block can be kept in an almost completely demagnetized state during non-excitation operation. Therefore, in order to adjust this demagnetization, there is no need to perform the above-mentioned extraction operation of the permanent magnet as in the conventional method, and it is possible to perform the adjustment work extremely easily without accidentally demagnetizing the permanent magnet more than necessary. Become.

Further, according to the present invention, even if a permanent magnet having a high coercive force such as a ferrite magnet is used as the permanent magnet, the above-mentioned adjustment for demagnetization is possible, and therefore, an almost complete demagnetization state can be obtained. Therefore, an inexpensive ferrite magnet can be used as the permanent magnet, which allows easy rotation of the permanent magnet and also prevents gaps between the magnetic attraction surface of the magnetic circuit block and the object to be attracted. It is possible to take advantage of the feature of ferrite magnets, which is the ability to effectively exert adsorption force.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a permanent magnet holding device according to the present invention, and FIGS. 2 and 3 are views similar to FIG. 1 showing other embodiments of the present invention. 12: Magnetic circuit block, 14: First permanent magnet, 16, 16': Second permanent magnet, 18, 18
-1, 2, 3: Magnetic member, 20, 20a, 20
b: non-magnetic member, 26: magnetic short-circuit member.

Claims (1)

[Scope of utility model registration request] a magnetic circuit block comprising a pair of magnetic members each having a magnetic attraction surface and a non-magnetic member disposed between the magnetic members; a first permanent magnet housed and fixed within the magnetic circuit block; a second permanent magnet rotatably disposed within the magnetic circuit block and rotatably operated in cooperation with the first permanent magnet to place the magnetic attraction surface in an energized state and a de-energized state; is arranged in the magnetic circuit block so as to be in magnetic contact with both the magnetic members in order to correct the unbalance of the magnetic flux induction amount of the first and second permanent magnets when the permanent magnet is in the non-excited rotational position. a switchable permanent magnet retaining device comprising: a magnetic shorting member;