JP2001112784A - Dental prosthesis attachment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dental prosthesis attachment having a stable non- magnetic area and exhibiting excellent magnetic attraction. SOLUTION: A dental prosthesis attachment is constructed of a magnet body 11, a yoke 12 provided with a recess 125 housing the magnet body 11 and formed of a soft magnetic material, a shield disc 15 arranged in a recess opening part 19 in the yoke 12 for sealing the magnet body 11 and formed of a soft magnetic material, and a ring-shaped non-magnetic modified member 18 arranged between the outer circumference part of the shield disc and the inner circumference part of the yoke and formed of a material prepared by fusing a soft magnetic material, Ni, and austenite stainless steel together. The yoke 12, the ring-shaped non-magnetic modified member 18 and a keeper 10 side disc end face 13 formed of the soft magnetic shield disc 15 are machined by grinding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small magnetic denture attachment capable of securing a required magnetic attraction force within a limited denture base.

[0002]

2. Description of the Related Art Conventionally, as a denture attachment utilizing a magnetic attraction force, for example, the one shown in FIGS. 8 and 9 has been proposed (Japanese Patent Laid-Open No. Hei 4-227253). As shown in FIG. 8, in order to mount the denture 80, the root portion 86 of the human body is used.
The base plate 85 is embedded in the base plate 85, and the keeper 10 is embedded in the root plate 85. The denture 80 is the keeper 1
The artificial tooth attachment 9 is provided so as to oppose the tooth 0, a resin bed 83 surrounding the denture attachment 9, and an enamel-like artificial tooth 84.

As shown in FIG. 9, the denture attachment 9 includes a magnet body 91 made of a columnar permanent magnet and magnetized in a direction in which a magnetic flux intersects an attraction surface that comes into contact with the keeper 10. It has a recess 99 for accommodating the magnet body 91 and a box-shaped yoke 92 made of a soft magnetic material. Further, the magnet body 91 is arranged in the recess opening 990 of the yoke so as to be sealed in the yoke 92. The shield plate 96 made of a soft magnetic material and the shield ring 97 made of a non-magnetic material are provided. The shield plate 96 and the shield ring 97 are collectively referred to as a seal plate 98. That is, the magnetic flux emitted from the magnet body 91 to fix the above-mentioned denture attachment to the keeper by magnetic attraction forms a magnetic circuit of the magnet body 91 → the shield plate 96 → the keeper 10 → the yoke 92 → the magnet body 91. That is. In order to form this magnetic circuit, a shield ring 97 made of a non-magnetic material is arranged between the shield plate 96 and the yoke 92 so as not to cause a magnetic short circuit. Each of the above members is made of a corrosion-resistant material.

Accordingly, in the above-described method of manufacturing the denture attachment, the butted portions of the outer periphery of the yoke 92 and the shield ring 97, and the inner periphery of the shield ring 97 and the outer periphery of the shield plate 96 are laser-welded.

[0005]

However, it has been found that the following problems remain from the structure and manufacturing method of the above-mentioned denture attachment. First, the non-magnetic shield ring 97 for preventing a magnetic short circuit and the welded portion between the inner periphery of the shield ring 97 and the outer periphery of the shield plate 96 allow soft magnetic flux through which a magnetic flux from the magnet body 91 to the keeper 10 passes. Since the shield plate 96 is narrowed, it causes a decrease in magnetic attraction. Secondly, when such double welding is performed, a gap or unevenness is generated in a butt portion between the yoke 92 and the outer periphery of the shield ring 97 due to distortion due to heat during welding. For this reason, a gap is formed between the denture attachment and the keeper, and the gap becomes a magnetic gap, which lowers the magnetic attractive force. In addition, laser welding is difficult at the butted portion between the inner periphery of the shield ring 97 and the shield plate 96, and welding cracks are likely to occur.

[0006] In order to solve these problems, in Proceedings of the Japan Institute of Metals (September 29, 1996), page 408, a denture attachment and a manufacturing method shown in FIGS. Proposed. The denture attachment shown in this document simplifies the structure and demagnetizes the necessary parts instead of the non-magnetic parts in order to reduce the non-magnetic parts and increase the parts that contribute to the formation of the magnetic circuit. I have.

The manufacturing method is as follows.
6 is provided with a Ni film 105 in advance. Next, the recess opening 108 of the yoke 102 containing the magnet body 101
Then, after the seal plate 106 is arranged and covered, the space between the yoke 102 and the outer periphery of the seal plate 106 is welded. At the time of this welding, the Ni film is melted, and the Ni film is
6 and melt. Thereby, the melting portion 109
(FIG. 10B) is made non-magnetic.

However, this structure has inevitable drawbacks due to the manufacturing method and drawbacks of the manufacturing method itself. That is, as shown in FIG. 10 (B), when the Ni coating is melted between the yoke 102 and the seal plate 106 to form the fusion zone 109 as shown in FIG. Is the solid line D in FIG.
As shown in the figure, it is necessary to form just the thickness of the seal plate 106. This attempts to demagnetize the space between the yoke 102 and the seal plate 104. However, from the prototype example based on this proposal, the base material (SU
Although the amount of Ni penetration into 30Cr-2Mo in S447J1) exceeds 15%, as can be seen from the structure of the stainless steel deposited metal shown in FIG. 7, ferrite remains and it can be said that demagnetization is difficult. Therefore, the yoke 10
A magnetic short circuit occurs between the seal 2 and the seal plate 106, and the magnetic attraction decreases. In this case, by using SUS430 (17Cr) with a small amount of Cr instead of SUS447J1 (30Cr-2Mo) as the base material, demagnetization can be achieved and a high suction force can be obtained, but severe corrosion in the oral cavity can be obtained. Under the circumstances, denture attachments are easily rusted and cannot be used.

Further, if the welding depth of the fusion portion 109 is increased as shown by a broken line E in the figure and the magnet body 101 is also melted, the magnet body 101 is damaged and the magnetic attraction force is reduced.

On the other hand, if the welding depth is reduced as shown by a dotted line F in FIG. 1 to avoid this danger, the Ni film, which is a soft magnetic material, remains unmelted.
A magnetic short circuit occurs between the yoke 102 and the seal plate 104, and the magnetic attraction decreases.

Further, the thickness of the seal plate 104 is very thin, for example, about 0.2 mm. Therefore, welding conditions for forming the fusion zone 109 are extremely severe. As described above, it is very difficult to form a non-magnetic region between the yoke 102 and the seal plate 104 in the above-described manufacturing method. Therefore, even if the non-magnetic region is formed, unevenness may occur at the butted portion between the yoke 102 and the seal plate 104. For this reason, a gap is formed between the denture attachment 9 and the keeper 10, and the gap becomes a magnetic gap to reduce the magnetic attraction force.

Further, melting by a laser is instantaneous due to a high energy density and is not sufficiently stirred, so that segregation occurs and a soft magnetic portion may be locally generated. Therefore, the yoke 102 and the seal plate 10
6, the necessary non-magnetic area is not sufficiently ensured, and the magnetic short-circuit is directly generated from the yoke 102 directly to the seal plate 104, and the magnetic attractive force is reduced.

When the seal plate 106 with the Ni film 101 is made larger and fitted into the recess opening 108 of the yoke 102, the Ni film 105 is formed by plating, so that the adhesion is insufficient. , Peeling may occur. In addition, due to the above-described peeling, the demagnetization of the molten portion may be insufficient due to an insufficient amount of Ni.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide a denture attachment having a stable and small non-magnetic region and having excellent magnetic attraction.

[0015]

According to a first aspect of the present invention, there is provided a denture attachment buried in a denture base so as to face a keeper made of a soft magnetic alloy buried in a root surface portion, wherein the magnet body and the magnet body are housed therein. A yoke made of a soft magnetic material having a recess formed therein, a shield plate made of a soft magnetic material disposed in a recess opening of the yoke so as to enclose the magnet body, an outer peripheral portion of the shield plate, and A ring-shaped non-magnetic modified member in which a soft magnetic material, Ni and stainless steel are fused, is provided between the yoke, the inner peripheral portion of the yoke, and the yoke, the ring-shaped non-magnetic modified member, and the soft magnetic material. A denture attachment characterized in that a circular end face on the keeper side made of a magnetic shield plate is machined by grinding.

The most remarkable point in the present invention is that the seal plate comprises a shield plate made of a soft magnetic material and a non-magnetic modification member fused to the outer periphery of the shield plate. The quality member and the inside of the yoke are fused together, and the end face magnetically attracted to the keeper is made thinner by grinding and made flat (FIG. 1). Further, one end face on the shield disk side of the columnar magnet body and furthermore, both end faces are processed (hereinafter, referred to as R processing) having rounded portions.

Next, the operation and effect of the present invention will be described.
In the denture attachment of the present invention, as described above, the seal plate is first formed by the shield plate made of a soft magnetic material and the nonmagnetic ring portion made of the nonmagnetic modified member fused to the outer periphery. . Further, in the present invention, the non-magnetic ring portion and the inside of the yoke are formed by fusing.

Further, in the present invention, the end face magnetically attracted to the keeper is thinned by grinding and flat. Further, at least the end face on the shield plate side of the cylindrical magnet body is rounded. That is, the end face of the cylindrical magnet body may be rounded on the shield plate side, and further the other end face may be rounded.

Therefore, according to the present invention, a stable and excellent non-magnetic region can be secured between the seal plate and the yoke. Further, as the seal plate is thinned by the grinding process, the non-magnetic region is also narrowed and reduced, so that the magnetic region of the shield plate effective for the magnetic circuit is enlarged, and the flat surface eliminates the magnetic gap. Therefore, it has excellent magnetic attraction. Further, by rounding the end surface of the cylindrical magnet body, the magnet body may be damaged by contact between the non-magnetic reformed portion heated at a high temperature and the magnet body when forming the non-magnetic modified member by laser heat. Since it is not received, the above excellent magnetic attraction force can be secured.

In the seal plate, as the soft magnetic material having excellent corrosion resistance used for the shield plate, 19
Cr-2Mo-0.2Ti-Fe, 17Cr-2Mo-
0.2Ti-Fe, 13Cr-2Mo-0.2Ti-F
e. In addition, the non-magnetic modified member constituting the non-magnetic ring portion includes a SUS30 between the shield plate and the yoke.
4. A stainless steel non-magnetic material such as SUS316, 316L and the like are arranged with Ni, and when the non-magnetic material and Ni are melted by laser heat, a part of the soft magnetic material of the shield plate and the yoke on both sides is melted together, A member formed by fusion.

In this non-magnetic modified member, the joint surface between the non-magnetic material and the soft magnetic material is fused by laser heat between the shield plate and the yoke based on the non-magnetic material. A stable and excellent non-magnetic region can be reliably formed between the seal plate and the yoke.

However, when the non-magnetic region composed of the non-magnetic modifying member is expanded, the magnetic region of the shield plate is reduced, and a magnetic gap is formed to prevent a magnetic circuit from the magnet body to the keeper, thereby reducing magnetic attraction. . Therefore, it is necessary to reduce the non-magnetic region enlarged during the non-magnetic modification as much as possible.

Also, due to the laser heat at the time of assembling the yoke and the shield plate and forming the nonmagnetic modified member, etc.
If a gap due to unevenness is formed on the circular end face on the keeper side composed of the yoke, the ring-shaped non-magnetic modification member, and the shield plate, the gap becomes a magnetic gap and the magnetic attraction force is reduced. Therefore, it is necessary to eliminate the magnetic gap as a flat surface.

In order to enlarge the magnetic region of the shield plate and to eliminate the magnetic gap, the circular end face on the keeper side is ground to reduce the non-magnetic region enlarged at the time of non-magnetic modification. The end face made of the yoke, the ring-shaped non-magnetic modification member, and the shield plate is flattened. Depending on the degree of unevenness due to non-magnetic regions or non-magnetic modification, depending on the thickness and flatness removed by grinding, from rough grinding to fine grinding,
Further, polishing is included as necessary.

Next, as in the second aspect of the present invention, it is preferable that the ring-shaped non-magnetic modified member has a stainless steel austenitic structure. That is, the nonmagnetic state can be further stabilized. As shown in FIG. 7 (structure of the welded metal of stainless steel), when the austenitic stainless steel disposed between the shield disk and the yoke made of a soft magnetic material melts, the joint surface with the shield plate or the yoke is formed. This is because the fusion of the austenitic stainless steel generates a martensite or ferrite region from the austenite region due to the fusion of the austenitic stainless steel, and the stabilizing effect of the non-magnetic region decreases when the fused portion diffuses inward from the joint surface. Therefore, it is necessary that at least the central portion of the ring-shaped non-magnetic modified member (the portion distant from the joint surface between the shield plate and the yoke) is made of stainless steel austenitic structure. Therefore, by forming a Ni coating on the outer periphery of the shield disk and fusing it with the austenitic stainless steel, it is possible to suppress the generation of martensite or ferrite regions when the austenitic stainless steel is melted.

Next, the ring-shaped non-magnetic modified member may include the non-modified non-magnetic member up to a half of its thickness. A non-magnetic region is formed between the shield disk and the yoke by having a ring-shaped non-magnetic modified member on the keeper side and a non-magnetic member made of austenitic stainless steel on the magnet body side. can do. In the case of this structure, the non-magnetic region formed by the ring-shaped non-magnetic modified member is reduced and the magnetic region formed by the shield disk is expanded, so that the efficiency of the magnetic circuit is improved and the magnetic attractive force is improved. .

Further, a circular end face on the keeper side comprising the yoke, the ring-shaped non-magnetic modified member and the soft magnetic shield disk is made flat by grinding at least 0.050 mm in thickness, The thickness of the shield disk is 0.050 to 0.150 mm. here,
The reason why the thickness removed by grinding is 0.050 mm is as follows.
This is because the thickness to be removed is necessary in order to remove a step, unevenness and distortion generated at the time of assembling the yoke and the shield disk or the like at the time of non-magnetic modification, and to obtain a flat surface. On the other hand, if the thickness is excessively removed to reduce the thickness, the non-magnetic region is reduced and the magnetic region is enlarged, but the magnet body may be exposed or the non-magnetic modified member may be eliminated. 0.050 mm is required. Conversely, if the removal is reduced and the thickness is reduced, the magnetic region cannot be expanded because there are many non-magnetic regions, and the denture attachment cannot be reduced due to the large height of the denture attachment. The upper limit was 0.150 mm.

The magnet body used in the present invention is a magnet having a high magnetomotive force per unit volume.
Rare earth magnets having a high energy product such as d-Fe-B are preferred. Moreover, the shape is a columnar shape, and at least one end is R-processed, and the NS pole or the S-pole is arranged in a direction in which the magnetic flux intersects the attracting surface that contacts the keeper.
The north pole is growing. R processing is 0.10 to 0.30mm
Of arc-shaped roundness. In order not to damage the magnet body by the laser heat at the time of forming the nonmagnetic modified portion, at least 0.10 mm R processing is necessary, while
If it exceeds 0.30 mm, a gap is formed between the shield plate and the shield plate made of a soft magnetic material, and magnetic attraction decreases. Furthermore, by performing R processing on both end surfaces of the cylindrical magnet body, the same or slightly larger R processing as the R part of the cylindrical magnet body is also performed on the corner of the recess of the yoke in which the cylindrical magnet body is fitted. While the end surface of the magnet body and the bottom surface of the yoke recess are in close contact with each other, and the magnet body side peripheral surface and the yoke recess inner peripheral surface can be in close contact with each other, the magnet body can be stored in the yoke recess without any gap. In this way, the magnet of the maximum size is accommodated in the yoke recess, and the magnetic flux at the shoulder of the yoke is smoothed by the R processing, and the magnetic attraction force is improved.

The yoke has a container shape for accommodating the magnet body, and is made of a corrosion-resistant soft magnetic material. That is, the yoke is required so as not to cause a problem in use in the oral cavity. It is necessary to have excellent magnetic properties in order to form a magnetic circuit that has corrosion resistance and transmits magnetic flux from a magnet. The material used for the yoke is 1
8Cr stainless steel, 17Cr-2Mo, 19Cr-
A corrosion-resistant soft magnetic material such as 2Mo stainless steel is preferable.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A denture attachment and a method of manufacturing the same according to the present invention will be described with reference to FIGS. As shown in FIG. 1, the denture attachment 1 of this embodiment has a magnet body 11, a recess 125 for accommodating the magnet body 11, and a yoke 12 made of a soft magnetic material. Shield disk 1 made of a soft magnetic material disposed in recess opening 19 of yoke 12
5, the outer peripheral portion of the shield disk 15 and the yoke 1
And a ring-shaped non-magnetic modified member 18 in which a soft magnetic material, a ring-shaped Ni film, and austenitic stainless steel are fused between the yoke 12 and the ring-shaped member. Circular end face 1 on the keeper 10 side comprising a non-magnetic modified member 18 and the above-mentioned soft magnetic shield disk
3 is a flat surface processed by grinding.

As shown in FIG. 2, a denture attachment 2 of the following example is similar to the denture attachment 1 shown in FIG.
Part of the nonmagnetic modified member 18 (1/2 or less of its thickness) becomes the nonmagnetic member 26, and the nonmagnetic modified member 28 is thin.

As shown in FIG. 3, the denture attachment 3 is similar to the denture attachment 1 shown in FIG.
In the yoke 12 having a recess 125 for accommodating the magnet body 11 and made of a soft magnetic material, the denture 8 shown in FIG.
As a modified example of the shape of the yoke so that the denture attachment does not easily fall off from the resin floor 83 of the "0.
K1 is comprised of a yoke 32 larger than the outer diameter DK2 of the surface to be bonded to the keeper.

The above-mentioned ring-shaped non-magnetic modified member is shown in FIG.
As shown in (A), after the magnet body 41 is housed in the recess 425 of the yoke 42, the shield disk 15 and the ring-shaped Ni film 17 and the austenitic stainless steel 16 on the outer circumference of the shield disk shown in FIG. Is disposed. Then, the austenitic stainless steel 66 and the Ni film 67 are heated and melted by a laser beam with focus. At this time, the surfaces of the soft magnetic materials on both sides are also melted, and the melt on the Ni film side has a high Ni concentration, and even if mixed with a Cr melt containing no Ni,
Cr melt is austenitic stainless steel melt (Cr
-Ni melt) to be solidified in a state where it is prevented from leaching out, and becomes a nonmagnetic modified member 48 showing an austenite structure.

When the depth of heating and melting by the laser beam is small, the ring-shaped Ni film 17 and the austenitic stainless steel 16 are not melted.

Here, the shield disk 15 shown in FIG. 6 and the seal plate 60 made of a ring-shaped Ni film 17 and an austenitic stainless steel 16 on the outer periphery of the shield disk are manufactured by the following method as a specific example. . As shown in FIG. 6, 19Cr-2Mo-0.2
SUS as a soft magnetic material 65 of Ti-Fe and a non-magnetic member
A shield plate 60 having a required thickness is formed by slicing a non-magnetic material 66 made of 316 and integrally formed with a Ni plating layer 67 interposed therebetween.

Next, a specific example of this embodiment will be described below with reference to FIG. In FIG. 4A, 19Cr
The yoke 42 made of a soft magnetic material of -2Mo-0.2Ti-Fe is a concave case having an outer diameter of 4.00 mm, a height of 1.45 mm, an opening diameter of 3.10 mm, and an outer diameter thickness of 0 for the case. .45 mm and a depth of 0.80 mm. The outer peripheral shoulder of the case has an outer diameter and a height of 0.4 mm each with a 45 degree inclination. The inner shoulder of the recess 425 of the case is formed of a 0.2 mm R portion.

As the magnet 41, (BH) max = 4
A 2MGOe Nd-Fe-B permanent magnet body was used. It has a cylindrical shape with a diameter of 3.05 mm and a height of 0.6 mm, and the upper and lower end faces are chamfered by 0.20 mmR.

The magnet body 41 is housed in a recess of the case (yoke 42), and the shield plate 60 is inserted into the recess opening 49.
Is arranged. The shield plate 60 has the configuration shown in FIG. 6, and the shield disk 15 made of a soft magnetic material of 19Cr-2Mo-0.2Ti-Fe has a diameter of 2.76 mm.
The Ni film 17 has a thickness of 0.01 mm, and the austenitic stainless steel 16 made of SUS316 has a thickness of 0.15 m.
m and a disk shape of 3.08 mm in diameter and 0.25 mm in thickness.

Next, as shown in FIG.
A non-magnetic modified member 48 is formed by irradiating a laser beam having a diameter of 200 μm with the 16 and the Ni film as focal points. The austenitic phase shown in FIG.

In the above manufacturing process, as shown in FIG. 4 (A), the magnet is housed in the recess of the case (yoke 42), and the case 4 is assembled when the shield plate 60 is disposed.
There is a step between the shield 26 and the shield plate 60. In addition, when the non-magnetic modified member is formed by the laser beam, as shown in FIG. 4 (B), the non-magnetic modified member and its peripheral portion are distorted, uneven, and the like. These steps,
About 0.15 mm of the distortion, the irregularities, and the like were removed using a # 500 grinding wheel with respect to the surface of the shield disk.
As a result, as shown in FIG. 1, the thickness of the shield disk was about 0.10 mm, and the width of the non-magnetic modified member on the keeper 10 side (the melting width by the laser beam) was 0.55 mm before grinding.
To 0.35 mm, and the diameter of the shield disk is 2.
As the diameter was enlarged from 40 mm to 2.60 mm, the circular end face 13 was able to obtain a flat surface, and a small denture attachment with excellent magnetic attraction was obtained.

That is, the magnetic attraction force of the denture attachment is 6.2 N / mm ² before grinding and 7.0 N after grinding.
/ Mm ² .

In the invention example shown in FIG. 2, after the assembly according to FIG. 4A, when irradiating a laser beam having a diameter of 200 μm with a focus on the SUS316 and Ni film, the amount of energy can be suppressed to reduce the energy of the non-magnetic modified member. In the formation, a part of the SUS 316 and the Ni film is not melted, and the nonmagnetic member 26 can be left. After the grinding, the thickness of the nonmagnetic modified member 28 was about 0.06 mm, and the thickness of the nonmagnetic member 26 was about 0.04 mm. In addition, the thickness of the shield disk was about 0.10 mm. And
The diameter of the shield disk was 2.65 mm. Therefore, the magnetic attraction force of the denture attachment is 7.5 N / m.
m ² was obtained.

In the embodiment shown in FIG. 3, the yoke 42 is a concave case in the assembly according to FIG.
4.20 mm outside diameter of DK1 and 4.00 mm outside diameter of DK1
It has an inclined outer peripheral surface of 1.3 mm in height from 2 parts to 1 part of DK, a height of 1.45 mm and an opening diameter of 3.10 m.
m, case outer diameter thickness 0.45 mm and depth 0.80
mm. The outer peripheral shoulder of the case has an inclination of 30 degrees and the outer diameter is smaller by 0.4 mm than DK2. The inner shoulder of the case recess 425 is 0.2 mm.
R section. The following manufacturing method is the same. Therefore, the magnetic attraction force of the denture attachment was 8.5 N / mm ² in the same manner as the invention example shown in FIG.
Also, the strength of the drop prevention by the tensile test is 110N in FIG.
/ Mm ² to 200 N / mm ² .

[0044]

The effect of the present invention will be described below with reference to FIG. Due to the non-magnetic modifying member 18 forming a non-magnetic region between the shield disk 15 made of a soft magnetic material and the yoke 12 made of a soft magnetic material, the magnetic circuit
1 → shield disk 15 → keeper 10 → yoke 12 → magnet body 11. Thus, first, a magnetic circuit having no magnetic flux leakage and excellent magnetic attraction is formed because of the stable nonmagnetic region formed by the nonmagnetic modifying member.

However, the non-magnetic region is to generate a magnetic air gap which can also be a factor of deteriorating the magnetic circuit. In addition, even when these denture attachments are assembled or non-magnetically modified, magnetic voids are generated due to unevenness and distortion. Therefore, the second is to increase the area through which the magnetic flux density passes in the magnetic circuit, that is, the magnetic area which is not affected at the time of the non-magnetic modification, by making the surface flat and reducing the non-magnetic area.

For example, in FIG. 5, the outer diameters before and after grinding (15 'and 15) of the shield disk made of a soft magnetic material, which is the magnetic region, are DS2 and DS1, and the outer diameters before and after grinding of the yoke (ground portion 12'). The inner diameters are DY2 and DY1, the outer diameter of the yoke is D, and the diameter of the magnet body is DM. The thicknesses before and after the grinding of the seal disk are T2 and T1, and the thickness to be ground is t. By removing the thickness t (T2-T1) by grinding, the nonmagnetic modified member 18 'is removed, and the magnetic region of the shield disk becomes ((DS2) ^2- (DS1) ² ).
× (π / 4), and the efficiency of the magnetic circuit with respect to the magnet body (diameter DM) is improved. In addition, the magnetic region of the yoke 12 that is in close contact with the keeper 10 is also removed by removing 12 ′.
((DY1) ^2- (DY2) ² ) × (π / 4).

As described above, according to the present invention, it is possible to provide a denture attachment which is stable and has a small non-magnetic region, and has a flat surface facing the keeper and which has excellent magnetic attraction.

[Brief description of the drawings]

FIG. 1 is an explanatory cross-sectional view of a denture attachment according to a first embodiment.

FIG. 2 is an explanatory cross-sectional view of a denture attachment according to a second embodiment.

FIG. 3 is an explanatory sectional view of a denture attachment according to a third embodiment.

FIG. 4 is an explanatory view showing a method for manufacturing a denture attachment in the first embodiment.

FIG. 5 is an explanatory view of a non-magnetic region and grinding in the method of manufacturing the denture attachment in the first embodiment.

FIG. 6 is a perspective view showing an integrated manufacturing method of the seal plate and the like in the embodiment.

FIG. 7 is an explanatory view of a denture in a conventional example.

FIG. 8 is a phase diagram showing the structure of a stainless steel deposited metal.

FIG. 9 is an explanatory view of a denture attachment in a conventional example.

FIG. 10 is an explanatory view of a denture attachment in another conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Denture attachment 10 ... Keeper 11 ... Magnet body 110 ... R part of magnet body (corner side of the recess of the yoke 12) 111 ... R part of magnet body (non-magnetic modification) 12 ... yoke 12 '... part of the yoke 12 removed by grinding 121 ... R part at the corner of the recess of the yoke 12 125 ... bottom surface of the recess of the yoke 12 13 ・ ・ ・ Circular end face 15 ・ ・ ・ Shield disk 15 ′ ・ ・ ・ Part of shield disk removed by grinding 16 ・ ・ ・ Austenitic stainless steel 17 ・ ・ ・ Ni coating 18 ・ ・ ・ Nonmagnetic Reforming member 18 ': Non-magnetic modifying member removed by grinding 19: Recess opening of yoke 12 26: Non-magnetic material 28: Non-magnetic modifying member 32: Yoke 41: magnet body 42: yoke 421 .. R portion 425 at the corner of the recess of the yoke 42 425... Bottom surface 426 of the recess of the yoke 42... Recess opening 60 ... seal plate 65 ... soft magnetic material 66 ... austenitic stainless steel 67 ... Ni plating layer 80 ... denture 83 ... resin floor 84 ... artificial teeth 85 ... root plate 86 ... tooth root 9 ... denture attachment 91 ... magnet body 92 ... yoke 96 ... shield plate 97 ... shield ring 98 ... shield plate 99 ... Recess 990 recess opening 101 magnet body 102 yoke 105 Ni coating 106 shield plate 108 recess opening 109 melting Part

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tadashi Taichi, Aomachi, Tokai City, Aichi Prefecture 1 Aichi Steel Co., Ltd.

Claims (4)

[Claims] 1. A denture attachment buried in a denture base so as to face a keeper made of a soft magnetic alloy buried in a root surface, comprising: a magnet body; a recess for accommodating the magnet body; A yoke made of a material, a shield plate made of a soft magnetic material disposed in a recess opening of the yoke so as to enclose the magnet body, and an outer peripheral portion of the shield plate and an inner peripheral portion of the yoke. A keeper made of a ring-shaped non-magnetic modified member in which soft magnetic material, Ni and austenitic stainless steel are fused, and the yoke, the ring-shaped non-magnetic modified member, and the soft magnetic shield plate A denture attachment characterized in that the side circular end face is machined by grinding. 2. The denture attachment according to claim 1, wherein the composition of the ring-shaped non-magnetic modified member comprises an austenitic structure of stainless steel. 3. The denture attachment according to claim 1, wherein the ring-shaped non-magnetic modified member includes a non-modified non-magnetic member up to a half or less of a thickness thereof. 4. A keeper-side circular end face comprising said yoke, said ring-shaped non-magnetic modified member and said soft magnetic shield plate is ground to a flat surface by grinding to a thickness of 0.050 mm or more, and said shield is formed. 0.050 plate thickness
2. The denture attachment according to claim 1, wherein the thickness is 0.150 mm.