JPH0634794B2 - Dental magnet - Google Patents

Description

TECHNICAL FIELD The present invention relates to a dental magnet using a rare earth magnet alloy.

2. Description of the Related Art In recent years, in the field of dental prosthesis technology, a technology for developing artificial tooth maintenance power by utilizing attractive force between rare earth magnets or between rare earth magnets and dental magnetic alloys will be developed and reach the stage of practical application. I am trying. This is an old idea, but recently, extremely powerful rare earth magnets such as samarium-
With the advent of cobalt magnets, neodymium-iron-boron magnets, etc., it has become possible to maintain artificial teeth with extremely small magnets.

Each of the above magnets is a type of metal called an intermetallic compound, and is hard and brittle. In addition, it has poor corrosion resistance, and when it is used to expose a magnet in the oral cavity, it immediately turns black and the magnetic force gradually decreases.

Usually, plating is generally performed as a method of imparting corrosion resistance to a metal having poor corrosion resistance. However, since this type of magnet is manufactured by the powder metallurgy method, a slight amount of holes are inevitably present and the plating property is not good. In addition, even if the plating is applied, the bare metal itself is fragile, so the impact may cause the corners to fall off. Therefore, it cannot be said that the human body is absolutely reliable in that it must be absolutely safe.

On the other hand, it should not maximize the performance of the magnet, but should not weaken it.

In other words, considering that it may be used by inserting it into the tooth in some cases, it is necessary to be small and strong as possible, and it is natural that the magnetic force should not be weakened.

The side surface of the rare earth magnet is fixed to the inside of the cap-shaped soft magnetic alloy by cement, and the outer crown in which the recess is formed by the edge of the cap and the other surface of the magnet, and the recess of the outer crown A safety device for a denture including an inner crown made of a soft magnet alloy having a convex portion to be fitted therein is disclosed in Japanese Patent Laid-Open No. Sho 58-58.
Known as No. 36542.

In this product, the inner crown is loaded on the root plate of the residual tooth, the outer crown is fixed by adhering to the inside of the denture, and the outer crown is fitted to the inner crown to close the magnet with a rare earth magnet as a magnetomotive force source. A channel is formed, and friction between the rare earth magnet and the soft magnetic alloy in the vertical direction and friction between the conical inner crown and the concave outer crown fitted to it in the lateral direction. The force or fitting force suppresses and maintains the stability of the denture.

Further, in JP-A-54-16891, page 8, upper left column, line 8 to left lower column, line 3 are provided with two magnet elements composed of rare earth magnets having end faces of magnetic poles opposite to each other, and The inner cylindrical portion is opposite to the tubular shaped portion with a gap and has opposite magnetic poles at their respective ends, and one end face is bridged by a disc-shaped integral cap, A denture holding device having a disc-shaped integral holding element made of ferromagnetic stainless steel is disclosed. The magnet element and the exposed magnetic pole surface of the magnet holding element have a thickness of 5 to 10 μm. It is described that it may be covered by a thin stainless steel or platinum plated gold liner (shim).

This is one in which a holding element is fixed to the tooth root side and a magnetic element having a denture fixed to the holding element is matched by magnetic force.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention is easy to manufacture, small in size, strong in magnetic force, and prevents corner portions of rare earth magnets from falling due to impact.
The object is to provide a reliable and safe dental magnet.

Means for Solving the Problems The dental magnet of the present invention is such that one magnetic pole surface of the rare earth magnet except one magnetic pole surface and the outer peripheral portion are closely adhered and coated with a magnetic alloy, and one magnetic pole surface of the magnet is used. The surface of the magnetic alloy is the same surface, and a flat plate made of a non-magnetic alloy is provided in close contact with these surfaces.

The magnetic alloy provided in close contact with the magnetic pole surface and the outer peripheral portion of the working magnet except the one surface of the working magnet acts as a yoke for closing the magnetic circuit into a closed magnetic circuit. The non-magnetic alloy provided in close contact with the same surface has the function of increasing the attractive force due to the leakage of magnetic flux from the surface, and the magnetic alloy and the non-magnetic alloy protect the internal magnet.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. First
The figure is a basic structural diagram of the present invention. Although the figure shows an example of a cylindrical magnet, it may be a prism or a deformed column.

In FIG. 1, the magnet 1 is covered with the magnetic alloy 2 in close contact with the magnetic pole surface and the outer peripheral portion of the magnet 1 except for one magnetic pole surface, and at the same time, the magnet 1 and the magnetic pole surface are magnetically coupled to each other. The surface of the alloy 2 is formed on the same surface, and a flat plate made of the non-magnetic alloy 3 is provided in close contact with the same surface.

As the magnet 1, a rare earth magnet is used, and the attraction force needs to be about 100 g or more from FIG. 5 showing the relationship between (BH) max and the attraction force with the maximum energy product of 20 MGOe or more.

Further, the magnetic alloy 2 plays a role of a yoke for closing the magnetic circuit into a closed magnetic circuit, which brings about an increase in attractive force. Therefore, of course, a sufficient magnetic permeability and a saturated magnetic flux density are required, and in particular, the saturated magnetic flux density is important and sufficient attraction force cannot be obtained unless the magnetic flux density is 500 G or more. Sufficient suction power is 200-300g, and I want at least 100g or more. The relationship between magnetic flux density and attractive force is shown in FIG.

The wall thickness t1 of the magnetic alloy 2 also has a great relationship with the attraction force characteristic. As a result of the experiment, as shown in FIG. 4, the suction force is maximized in the vicinity of 0.5 mm, and the suction force is reduced regardless of whether it is thick or thin. It was also found that this optimum wall thickness changes depending on the saturation magnetic flux density of the magnetic alloy 2, and moves to the thinner side as the saturation magnetic flux density increases.

The wall thickness is related to the attractive force and the distance (d) between the magnet structure and the magnetic material to be attracted, and the relationship is shown in FIG.
A is the case of a single magnet, and B is the case of the present invention.
The suction force of B is much higher than that of A when d is small. As is clear from the figure, the action of the magnetic alloy 2 as a yoke increases the attraction force when d is small, but decreases like A when d increases. The intersection of A and B also changes depending on the saturation magnetic flux density and magnetic permeability of the magnetic alloy 2, but if the material is the same, it changes greatly with the wall thickness t1. In the case of using it for dentistry, there is a case where it is desired to prevent the suction force from being lowered so much even if the value of d becomes slightly large depending on the case. Therefore, the meat pressure may be made a little thin to bring the intersection of A and B to the larger d. Since the greatest role of the magnetic alloy 2 is to protect the magnet, d needs to be 0.2 mm practically from that point of view, and the wall thickness t1 has an optimum value of about 0.5 mm as described above. Therefore, it is necessary to limit the maximum to 0.7 mm or less. If it exceeds 0.7 mm or less than 0.2 mm, the suction force will be less than 100 g from Fig. 4.

Next, regarding the non-magnetic alloy 3, naturally, it is preferable that the magnetic permeability is as low as possible. Moreover, for the role of protection, the minimum thickness t2 is required to be 10 μm, and if it is thick, the suction force cannot be effectively used as can be seen from FIG. Therefore, the limit is 100 μ. The lower the magnetic permeability, the better, but practically up to 20 is allowed.

The magnetic alloy 2 provided in close contact with the other magnetic pole surface and the outer peripheral portion of the magnet 1 except the one surface thereof functions as a yoke for closing the magnetic circuit into a closed magnetic circuit. The non-magnetic alloy 3 provided in close contact with the same surface leaks the magnetic flux unbundled by the magnetic alloy 2 from its surface, increases the attractive force due to the presence of the leakage magnetic flux, and is provided on the tooth root side not shown. The magnetic alloy 2 and the non-magnetic alloy 3 protect the internal magnet 1 while producing a strong attractive force between the magnet and the magnetic alloy.

As described above, according to the present invention, one magnetic pole surface of the rare earth magnet except one magnetic pole surface and the outer peripheral portion of the rare earth magnet are closely adhered and coated with the magnetic alloy. The surface of the magnet is the same as the surface of the magnet, and a non-magnetic alloy is closely attached to these surfaces. The alloy is the shortest magnetic circuit with no magnetic loss, and the non-magnetic alloy provided in close contact with one magnetic pole and the same surface of the magnetic alloy is easy to manufacture because it can be formed on a single plane. The magnetic flux from the rare earth magnet and magnetic alloy leaks from the entire surface, and the attractive force is increased by the magnetic flux leaking from the rare earth magnet and magnetic alloy, and a strong attractive force is generated between the magnet or magnetic alloy provided on the tooth root side. Magnetic alloy and non-magnetic alloy as well as generate Since it covers the entire surface of the rare earth magnet inside and protects it, it is small and has a strong magnetic force, and the rare earth magnet does not fall down due to impact, and is reliable and safe for use on the human body.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of the present invention, and FIG. 2 is a thickness area sufficiently large in a direction perpendicular to the nonmagnetic alloy 3 of the magnet structure of FIG.
A curve showing the relationship between the attractive force and the distance d when a magnetic material having magnetism is placed, where A is a single magnet with the same outer diameter, and B is a
Shows the structure of FIG. In this case, the thickness of the non-magnetic material is 0. FIG. 3 is a curve showing the relationship between the saturation magnetic flux density of the magnetic alloy 2 and the attractive force, FIG. 4 is a curve showing the relationship between the thickness t of the magnetic alloy 2 and the attractive force, and FIG. 5 is (BH). 5 is a curve showing the relationship between max and suction force. 1 ... Magnet, 2 ... Magnetic alloy, 3 ... Non-magnetic alloy.

Claims (4)

[Claims] 1. A rare earth magnet, except for one magnetic pole surface, the other magnetic pole surface and the outer peripheral portion are closely adhered and coated with a magnetic alloy, and one magnetic pole surface of the magnet and the magnetic alloy surface are made to be the same surface. At the same time, a flat plate made of a non-magnetic alloy is provided in close contact with these surfaces to provide a dental magnet. 2. The rare earth magnet has a maximum energy product of 20 MG.
The dental magnet according to claim 1, which is Oe or more. 3. A magnetic alloy having a saturation magnetic flux density of 5000 G or more,
Permeability is 100 or more and the wall thickness of the coating is 0.2-0.7mm
The dental magnet according to claim 1, wherein: 4. The dental magnet according to claim 1, wherein the non-magnetic alloy is a substantially non-magnetic alloy having a magnetic permeability of 20 or less, and the wall thickness is 10 μ or more and 100 μ or less.