JP3867903B2 - Method for manufacturing orthodontic member - Google Patents

Description

【０２５８】
表１に示すように、実施例１で得られたブラケットは、機械的強度（抗折力）および表面の硬度が高い。また、実施例１で得られたブラケットは、生体適合性および審美性も優れている。
【０２５９】
【発明の効果】
以上述べたように、本発明によれば、複雑な形状のものでも容易に製造でき、高い寸法精度を有する高密度（低空孔率）の歯列矯正部材を得ることができる。そして、押出成形によるため、生産性が高く、歯列矯正部材の量産に適する。
【０２６０】
また、従来、加工が困難であった硬質材料等についても、それを用いて歯列矯正部材を製造することができ、歯列矯正部材の機能・形状（デザイン）の拡大を図ることができる。
【０２６１】
また、切断長さを調整することにより、何種類もの歯列矯正部材を容易に製造することができるので、生産性に優れ、安価に歯列矯正部材を供給することができる。
【０２６２】
また、Ｔｉ系金属材料で構成されているものの場合、焼結体中のＣ、Ｏ、Ｎの含有量を低減することができるので、延性（靭性）の高い歯列矯正部材が得られる。
【図面の簡単な説明】
【図１】本発明の歯列矯正部材の製造方法の第１実施形態を示す工程図である。
【図２】本発明の歯列矯正部材（歯列矯正用ブラケット）の構成例を示す斜視図である。
【図３】図２に示す歯列矯正部材の底面図である。
【図４】本発明の製造方法の製造工程で得られる長尺な成形体の構成例を示す斜視図である。
【符号の説明】
１…歯列矯正用ブラケット、２…基部、３…係合部（タイウイング）、３１〜３４…突部、３５、３６…凸条、４、５…スロット（溝）、６…底面（裏面）、６１…凹凸、７、８…溝、１０…長尺成形体、１Ａ〜４Ａ…工程[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing an orthodontic member.
[0002]
[Prior art]
2. Description of the Related Art Orthodontic brackets and wires for correcting dentition are known as dental instruments (dental parts) used in the oral cavity.
[0003]
An orthodontic bracket (hereinafter simply referred to as a “bracket”) has a base portion that is adhesively fixed to a tooth and an engaging portion formed on the upper portion of the base portion. A wire is inserted through the wire, and this wire is tensioned to correct the dentition.
[0004]
Such a bracket is made of a metal material or ceramics, and is manufactured (processed) by the following method.
[0005]
[1] A method of obtaining a desired shape by machining a metal or ceramic plate.
[2] A method of obtaining a desired shape by subjecting a metal plate to electric discharge machining.
[3] A method of injection molding (MIM) a compound obtained by kneading metal or ceramic powder and a binder into a desired shape, and degreasing and sintering the obtained molded body.
[0006]
However, the method [1] has a problem in that it requires a lot of labor and time for manufacturing because all the complex shaped brackets are manufactured by machining, and is unsuitable for mass production. In addition, ceramics are difficult to machine because of their high hardness, and there is a problem that applicable materials are limited.
[0007]
In addition, the method [2] also requires a lot of labor and time to manufacture a bracket having a complicated shape, and the material is required to be conductive, so that it cannot be applied to a ceramic product. There is.
The method [3] has a problem that, for example, when a bracket having a different length is to be manufactured, a molding die must be prepared for each bracket.
[0008]
[Problems to be solved by the invention]
An object of the present invention is to provide a method of manufacturing an orthodontic member that is easy to manufacture, suitable for mass production, and has a wide range of material selection.
[0009]
[Means for Solving the Problems]
Such an object is achieved by the present invention described in (1) below.
[0010]
(1) A molding step of obtaining a long shaped body having a cross-sectional shape corresponding to the cross-sectional shape of the orthodontic member by extrusion molding using a compound containing raw material powder;
Forming a groove corresponding to the slot in the long shaped body by machining using a dicing machine;
A cutting step of cutting the long molded body in which the groove is formed into a predetermined length;
A degreasing step of performing a degreasing process on the cut molded body to obtain a degreased body;
And a sintering step of obtaining a sintered body by sintering the degreased body subjected to the degreasing treatment.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the manufacturing method of the orthodontic member of this invention is demonstrated in detail based on suitable embodiment shown to an accompanying drawing.
[0030]
FIG. 1 is a process diagram showing a first embodiment of a method for producing an orthodontic member of the present invention, and FIG. 2 is a perspective view showing a configuration example of an orthodontic member (orthodontic bracket) of the present invention. FIG. 3 is a bottom view of the orthodontic member shown in FIG. 2, and FIG. 4 is a perspective view showing a configuration example of a long molded body obtained in the manufacturing process of the manufacturing method of the present invention.
[0031]
First, as an example of an orthodontic member, a configuration example of an orthodontic bracket will be described with reference to FIGS. 2 and 3. As shown in FIG. 2, an orthodontic bracket (hereinafter simply referred to as “bracket”) 1 includes a plate-like base (bracket base, bracket stem) 2 and an engaging portion (projecting from the base 2). Tie wing) 3
[0032]
A slot (groove) 4 into which a wire (not shown) is inserted is formed at the center of the engaging portion 3. The slot 4 extends in a direction parallel to the longitudinal direction of the long molded body 10 to be described later.
[0033]
The engaging portion 3 is formed with another slot (groove) 5 that intersects with the slot 4 and extends in a direction perpendicular to the longitudinal direction of the long molded body 10. By these slots 4 and 5, the engaging portion 3 is divided into two pairs of claw-shaped protrusions 31, 32, 33, and 34 that spread outward.
[0034]
In addition, although the cross-sectional shape of the slots 4 and 5 in this embodiment has each comprised the rectangle, it is not restricted to this, For example, V shape and U shape may be sufficient.
[0035]
Such a bracket 1 is used by bonding and fixing the bottom surface (back surface) 6 of the base portion 2 to a tooth with an adhesive. In order to increase the adhesive strength, minute irregularities 61 are formed on the bottom surface 6 of the base 2.
[0036]
In the configuration shown in the drawing, the irregularities 61 are formed in a lattice shape, but, for example, grooves formed in a streak shape, or convex portions (protrusions) arranged regularly or irregularly (scattered dots). Or a recessed part (dimple) etc. may be sufficient.
[0037]
Next, 1st Embodiment of the manufacturing method of an orthodontic member is described based on FIG.1, FIG.2, FIG.3 and FIG.
[0038]
[1A] Manufacture of molded body
In this invention, a molded object is manufactured by the extrusion method (extrusion molding) using the mixture (compound) containing raw material powder.
[0039]
This extrusion molding method is a processing method in which a compound is supplied into a cylinder of an extrusion molding machine, pressed and extruded from the mouth of a die (molding die), and continuously extruded while regulating the cross-sectional shape. This processing method has an advantage that a long molded body (long molded body 10) can be continuously manufactured.
[0040]
In particular, in the case of extrusion molding in which a cylinder and a molding die are heated, the extrusion resistance of the mixture can be reduced, and the moldability is excellent and more preferable.
[0041]
Hereinafter, the production of the molded body by the extrusion molding method will be described.
First, raw material powder and a binder (organic binder) are prepared, and these are kneaded by a kneader to obtain a kneaded product.
[0042]
Examples of the raw material powder include metal powder and ceramic powder.
Examples of the metal material constituting the metal powder include Ti, Ti-based alloys, stainless steel, and the like, and Ti or Ti-based alloys are preferable in terms of excellent biocompatibility.
[0043]
Although the average particle diameter of metal powder is not specifically limited, Usually, 0.5-150 micrometers or less are preferable and about 1-100 micrometers is more preferable.
[0044]
In this invention, since it shape | molds by extrusion molding, the metal powder of a comparatively small particle size can be used. As a result, the sintered density of the finally obtained bracket 1 can be increased, and high strength can be obtained.
[0045]
In addition, the manufacturing method of metal powder is not specifically limited, For example, what was manufactured by the water or gas atomizing method, the reduction method, the carbonyl method, and the grinding | pulverization method can be used.
[0046]
Next, the ceramic material constituting the ceramic powder (hereinafter simply referred to as “ceramic material”) is not particularly limited. For example, ZrO ₂ (Including partially stabilized zirconia), Y ₂ O ₃ , Al ₂ O ₃ TiO ₂ And oxide phosphate ceramics such as calcium phosphate ceramics such as hydroxyapatite.
[0047]
The average particle size of the ceramic powder is not particularly limited, but is usually preferably 30 μm or less, and more preferably about 0.1 to 10 μm.
[0048]
In the present invention, since molding is performed by extrusion molding, even a ceramic powder having a relatively small particle diameter can be easily molded. As a result, the sintered density of the finally obtained bracket 1 can be increased, and high strength can be obtained.
[0049]
In addition, the manufacturing method of ceramic powder is not specifically limited, For example, what was manufactured by the grinding | pulverization, the spray pyrolysis method, the coprecipitation method, the glass crystallization method, and the sol-gel method can be used.
[0050]
Examples of the binder (binder) include polyolefins such as polyethylene, polypropylene, and ethylene-vinyl acetate copolymers, acrylic resins such as polymethyl methacrylate and polybutyl methacrylate, styrene resins such as polystyrene, polyvinyl chloride, and poly Various resins such as vinylidene chloride, polyamide, polyester, polyether, polyvinyl alcohol, or copolymers thereof, various waxes, paraffin, higher fatty acids (eg, stearic acid), higher alcohols, higher fatty acid esters, higher fatty acid amides, etc. 1 type or 2 types or more of these can be mixed and used.
[0051]
Further, a plasticizer may be further added. Examples of the plasticizer include phthalic acid esters (eg, DOP, DEP, DBP), adipic acid esters, trimellitic acid esters, sebacic acid esters, and the like, and one or more of these are mixed. Can be used.
[0052]
In the kneading, in addition to the raw material powder, the binder, and the plasticizer, various additives such as a lubricant, an antioxidant, a degreasing accelerator, and a surfactant can be added as necessary. .
[0053]
The kneading conditions vary depending on various conditions such as the composition and particle size of the metal powder or ceramic powder to be used, the composition of the binder, the additive, and the blending amount thereof. For example, the kneading temperature is about 35 to 270 ° C., Kneading time: about 10 to 240 minutes.
[0054]
In the present invention, since it is based on the extrusion molding method, high fluidity is not required as compared with the powder injection molding method (MIM method or the like), so that the content of the binder or the like in the compound can be reduced. Thereby, first, a sintered body having a low porosity and a high sintering density is obtained, and as a result, a high-strength orthodontic member is obtained. In addition, since the number of pores on the surface is reduced, the orthodontic member is less likely to be eaten by meals and germs. Secondly, when it is made of Ti or a Ti-based alloy, the amount of C and O in the sintered body can be reduced, and an orthodontic member having high toughness can be obtained.
[0055]
Next, the kneaded product obtained above is used to extrude with an extruder, thereby producing a long shaped body 10 having a desired cross-sectional shape.
[0056]
In this case, the cross-sectional shape of the long molded body 10 is determined by selecting an extrusion die (molding die) attached to the extruder. The cross-sectional shape is constant over the entire length of the long molded body 10. In addition, the cross-sectional shape and dimension of the long molded body 10 to be manufactured are determined in consideration of the shrinkage of the molded body due to subsequent degreasing and sintering.
[0057]
Moreover, the length of the long molded object 10 is not specifically limited, For example, it can be set as about 20-400 mm.
[0058]
Extrusion molding conditions vary depending on various conditions such as the composition and particle size of the raw material powder to be used, the composition of the binder and the blending amount thereof. For example, the cylinder temperature is preferably about 100 to 350 ° C. The mold temperature is preferably about 30 to 150 ° C., the extrusion speed is preferably about 0.1 to 50 mm / sec, and the extrusion pressure is preferably 1000 kgf / cm. ² It is as follows.
[0059]
Here, in order to improve the moldability, it is preferable that the mold temperature is set to a relatively low temperature as described above, and the compound is cooled and solidified in the mold.
[0060]
The content of the raw material powder in the molded body is preferably about 70 to 98 wt%, and more preferably about 80 to 98 wt%. If it is less than 70 wt%, the shrinkage rate when the molded body is sintered increases, and the dimensional accuracy decreases. On the other hand, if it exceeds 98 wt%, the content of the binder is relatively reduced, so that the fluidity at the time of molding becomes poor, and extrusion molding becomes impossible or difficult, or the composition of the molded body becomes non-uniform.
[0061]
As shown in FIG. 4, the long molded body 10 manufactured as described above has the extrusion direction during extrusion as the longitudinal direction, and its cross-sectional shape is constant. A groove corresponding to the slot 4 is formed in the long molded body 10. Moreover, the convex strips 35 and 36 for forming each protrusion 31-34 of the engaging part 3 are formed, and the groove | channels 7 and 8 are formed inside these convex strips 35 and 36, respectively.
[0062]
[2A] Cutting of compact
After forming a groove corresponding to the slot 5 by machining as described later on the long molded body 10 (long body) obtained in the step [1A], the long molded body is predetermined. Cut to length.
[0063]
The long molded body 10 is usually cut using a cutting device such as a metal saw or a cutter.
[0064]
From one long molded body 10, a plurality (for example, about 5 to 100) of molded bodies (cut bodies) are obtained. In this case, each cut body obtained by cutting is not limited to the same length, and may have different lengths. As described above, according to the present invention, various types of orthodontic members having different lengths can be easily manufactured by changing the cutting length.
[0065]
The cutting length of the molded body at this time is determined in consideration of the shrinkage of the molded body due to subsequent degreasing and sintering, but the length (L) of the bracket 1 finally obtained is 1 mm or more. It is preferable to cut so that it is about 2 to 10 mm. If the cutting length is too small, the cutting cycle becomes short, it is difficult to maintain dimensional accuracy, and the stability is poor.
[0066]
Further, since the molded body has a lower hardness than the sintered body, it can be easily cut regardless of the composition of the raw material powder, and is excellent in workability. Thereby, compared with the case where a hard sintered body is cut, it is possible to easily cut without using a cutting blade made of a cemented carbide or the like, a diamond cutter, or the like, so that the equipment of the cutting apparatus can be simplified. Further, since the hardness of the object to be cut is low, the burden on the cutting blade (wear, damage, etc.) is reduced, and the service life is extended.
[0067]
[3A] Degreasing treatment of molded body
A degreased body is obtained by performing a degreasing process (debinding process) on the molded body (cut body) cut in the step [2A].
[0068]
The degreasing treatment is not particularly limited, but it is a non-oxidizing atmosphere, for example, under a reduced pressure (vacuum) state (for example, 1 × 10 10 ² ~ 1x10 ^-6 Torr), or by performing heat treatment in an inert gas such as nitrogen gas or argon gas.
[0069]
In this case, the degreasing treatment is preferably performed at a temperature of about 150 to 750 ° C. for about 20 to 2200 minutes, more preferably at a temperature of about 250 to 650 ° C. for about 50 to 1300 minutes.
[0070]
Further, degreasing by such heat treatment may be performed in a plurality of steps (stages) for various purposes (for example, the purpose of shortening the degreasing time). In this case, for example, a method in which the first half is degreased at a low temperature and the second half is at a high temperature, and a method in which a low temperature and a high temperature are repeated are included.
[0071]
Moreover, you may change the pressure of the atmosphere in degreasing | defatting by the combination with the above-mentioned heat processing. In this case, for example, the first half of degreasing is reduced in pressure (for example, 1 × 10 ^-3 In the Torr) state, there are a method in which the latter half of the degreasing is performed at normal pressure and a method in which reduced pressure and normal pressure are alternately repeated.
[0072]
As described above, by changing the degreasing conditions, the molded body can be degreased more efficiently.
[0073]
In addition, you may perform this degreasing process by eluting the specific component in other methods, for example, a binder and an additive, using a predetermined solvent (liquid, gas).
[4A] Sintering of degreased body
The degreased body obtained as described above is fired and sintered in a furnace to produce a sintered body (metal sintered body or ceramic sintered body).
[0074]
By sintering, the raw material powder diffuses, grows, and becomes crystal grains. In this case, the voids disappear and a sintered body that is dense as a whole, that is, has a high density and a low porosity can be obtained.
[0075]
The sintering temperature in the sintering is, for example, preferably about 950 to 1500 ° C., more preferably about 1000 to 1450 ° C. when the metal composition is Ti or a Ti-based alloy, and preferably 1000 to 1550 in the case of stainless steel. In the case of ceramics, it is preferably about 1300 to 2200 ° C, more preferably about 1400 to 1850 ° C.
[0076]
Note that the sintering temperature may be varied (increased or decreased) with time within or outside the above-described range.
[0077]
In the case of the sintering temperature as described above, the sintering time is preferably about 30 to 480 minutes, more preferably about 60 to 300 minutes.
[0078]
In addition, the sintering atmosphere is not particularly limited, but when the raw material powder is a metal powder, it is preferably a reduced pressure (vacuum) or non-oxidizing atmosphere. Thereby, while preventing the characteristic deterioration by metal oxidation, it contributes to the reduction of the porosity of a sintered compact. Further, when the raw material powder is ceramic, it is preferable to be in the air or an inert gas atmosphere. This contributes to a reduction in the porosity of the sintered body.
[0079]
As a preferable sintering atmosphere, when the raw material powder is a metal powder, it is 1 Torr or less (more preferably 1 × 10 ^-2 ~ 1x10 ^-6 (Torr) under reduced pressure (vacuum), or an inert gas atmosphere such as nitrogen gas or argon gas at 1 to 760 Torr, or a hydrogen gas atmosphere at 1 to 760 Torr. When the raw material powder is ceramic, it is preferably an inert gas atmosphere such as a nitrogen gas of 1 to 760 Torr or an argon gas, or an air atmosphere of 1 to 760 Torr.
[0080]
By performing sintering under the above conditions, the porosity of the sintered body can be reduced. The porosity of the obtained sintered body is preferably 7 vol% or less, and more preferably 5 vol% or less. The reduction in porosity contributes to higher density of the sintered body, as well as high strength, high dimensional accuracy, prevention of sintering defects, good appearance, and good sintering efficiency. Sintering can be performed in a short sintering time, and productivity is improved.
[0081]
Sintering may be performed in two stages or more. For example, primary sintering and secondary sintering with different sintering conditions (sintering temperature, sintering time, sintering atmosphere, etc.) can be performed. In this case, the sintering temperature of secondary sintering can be higher than the sintering temperature of primary sintering. Thereby, the efficiency of sintering can be further improved, and the porosity can be further reduced.
[0082]
When the sintered body contains Ti as a basic component, that is, when it is composed of Ti or a Ti-based alloy (hereinafter referred to as “Ti-based metal material”), the sintered body has C: 0.01-0. It preferably contains 5 wt%, O: 0.02 to 0.8 wt%, and N: 0.01 to 0.6 wt%.
[0083]
Ti-based metal materials are lightweight and high-strength, are not easily deformed or damaged, have excellent durability and corrosion resistance, have very little elution of metal components, and suppress the onset of metal allergies. Excellent compatibility. Furthermore, since Ti metal material has less metallic luster than stainless steel, there is an advantage that aesthetics are not impaired when the bracket 1 is mounted.
[0084]
In the Ti-based metal material constituting the sintered body, C, O, and N exist, for example, in a form that forms a compound with Ti, but these elements are present in appropriate amounts in the Ti-based metal material. By being contained, physical properties such as strength, hardness, ductility (toughness), and elasticity suitable as an orthodontic member (dental appliance) can be maintained.
[0085]
The content of C in the Ti-based metal material is preferably about 0.01 to 0.5 wt%, more preferably about 0.03 to 0.25 wt%, still more preferably 0.03 to 0.15 wt%. It is said to be about. If the C content is less than 0.01 wt%, the material strength decreases when the O and N content is low, and if it exceeds 0.5 wt%, the ductility of the material may decrease.
[0086]
The content of O in the Ti metal material is preferably about 0.02 to 0.8 wt%, more preferably about 0.06 to 0.6 wt%, and still more preferably 0.06 to 0.4 wt%. It is said to be about. When the O content is less than 0.02 wt%, the material strength is lowered when the C and N contents are low, and when it exceeds 0.8 wt%, the ductility of the material may be lowered.
[0087]
The content of N in the Ti metal material is preferably about 0.005 to 0.6 wt%, more preferably about 0.01 to 0.18 wt%, more preferably 0.01 to 0.09 wt%. It is said to be about. When the N content is less than 0.005 wt%, the material strength decreases when the C and O content is low, and when it exceeds 0.6 wt%, the ductility of the material may decrease.
[0088]
Further, the total content of C, O and N in the Ti-based metal material is preferably about 0.035 to 1.2 wt%, more preferably about 0.08 to 0.95 wt%, More preferably, it is about 0.08 to 0.6 wt%. If the total content is less than 0.035 wt%, the material strength is lowered, and if it exceeds 1.2 wt%, the ductility of the material may be lowered.
[0089]
Further, in Ti-based metal materials, for example, other elements such as Fe, Ni, Cr, Pd, Co, Zr, Al, V, and Mo inevitably or actively cause problems such as metal allergy. You may contain in the range which is not. Addition of these elements contributes to an increase in strength of the metal material. These elements are preferably present in the form of an alloy with Ti or an intermetallic compound.
[0090]
In the present invention, for any purpose, there may be a pre-step of step [1A], an intermediate step existing between steps [1A] to [4A], or a post-step of step [4A]. Good. In this case, as intermediate processes and post-processes (post-processes), for example, deburring, chamfering (for example, chamfering near the edge of the cut surface), surface treatment such as cleaning, polishing, cutting, transfer (compression), Examples thereof include mechanical processing such as grinding and blasting (for example, shot blasting), chemical processing such as chemical etching, and various processing such as laser processing and electric discharge processing.
[0091]
In particular, the bracket 1 having the slots (grooves) 5 and the concavo-convex 61 as described above can be obtained by performing the above processing as an intermediate step and a post-step (post-processing).
[0092]
In addition, as a method for forming the grooves corresponding to the slots (grooves) 5 and the unevenness corresponding to the unevenness 61, machining is particularly preferable among the above processes. Thereby, it becomes possible to process easily any of a molded object, a degreased body, and a sintered body.
[0093]
A dicing machine having a rotatable grindstone is used to form a groove corresponding to the slot 5 by machining. When such a dicing machine is used, the width of the groove to be formed corresponds to the thickness of the grindstone.
[0094]
When the above-described processing is performed on the molded body, the processing can be performed more easily.
[0095]
Moreover, when performing the above processes on a degreased body, the process can be performed easily and accurately.
[0096]
Further, when the above-described processing is performed on the sintered body, the accuracy of the processing is particularly excellent. Therefore, when the finally obtained bracket 1 is required to have higher dimensional accuracy, it is preferable to perform the above-described processing on the sintered body.
[0097]
Further, the width of the slot 5 may be the same for each bracket 1 or may be different.
[0098]
Moreover, even if the above-described processing is performed on a long body (long molded body 10), it is performed on a cut body (cut molded body, degreased body, or sintered body). However, it is preferably applied to the long body.
[0099]
Thereby, for example, when a groove corresponding to the slot 5 is formed in the long body (long shaped body 10), the alignment can be easily performed. Moreover, such a groove | channel can be formed easily and continuously.
[0100]
Such processing may be performed a plurality of times. For example, the slot 5 (or the corresponding groove) and the unevenness 61 (or the corresponding unevenness) may be formed in different steps.
[0176]
As mentioned above, although preferred embodiment of the manufacturing method of the orthodontic member of this invention was described, this invention is not limited to these.
[0178]
For example, in the above-described embodiment, the method of performing the degreasing process only once has been described. However, the degreasing process may be performed twice or more. For example, primary degreasing and secondary degreasing with different degreasing conditions (at least one of a degreasing temperature, a degreasing time, and a degreasing atmosphere) can be performed. In this case, intermediate processing such as machining may be performed between the primary degreasing and the secondary degreasing.
[0179]
【Example】
Next, specific examples of the method for manufacturing an orthodontic member of the present invention will be described.
[0180]
Example 1
As a raw material powder (metal powder), a Ti powder having an average particle diameter of 20 μm manufactured by a gas atomization method was prepared.
[0181]
This metal powder: 91 wt%, a binder composed of polystyrene (PS): 2.7 wt%, ethylene-vinyl acetate copolymer (EVA): 2.7 wt%, and paraffin wax: 2.3 wt%, and dibutyl Phthalate (plasticizer): 1.3 wt% was mixed, and these were kneaded in a kneader at 100 ° C. for 60 minutes.
[0182]
Next, using this kneaded material (compound), in an extruder, an irregular cross section shown in FIG. 4 (for bracket: cross-sectional area = 3.5 mm) ² ) Long molded body (long molded body) was extruded. The molding conditions at the time of extrusion molding are as follows: cylinder temperature 140 ° C., mold (outlet part) temperature 70 ° C., extrusion pressure 120 kgf / cm. ² The extrusion speed was 10 mm / sec. Content of the metal powder in the obtained long molded object was about 91 wt%.
[0183]
The long molded body thus obtained was machined to form a groove corresponding to the slot (groove) 5 in FIG. The grooves were formed using a dicing machine equipped with a rotatable grindstone.
[0184]
Next, the long shaped body subjected to the machining as described above is cut into a predetermined length, and the cut length is 4.5 mm (target dimension after sintering: cut length: 4 mm) 50 compacts (cut bodies) were obtained.
[0185]
Next, degreasing treatment was performed on these cut compacts (cut bodies) using a degreasing furnace. Degreasing conditions are 1 × 10 ^-3 Under reduced pressure of Torr, the temperature was set to 500 ° C. × 60 minutes.
[0186]
Next, the degreased body that had been degreased was sintered using a sintering furnace to obtain a sintered body. The sintering condition is 1 × 10 ^-3 Under reduced pressure of Torr, the temperature was 1200 ° C. × 180 minutes.
[0187]
Asperities 61 were formed by machining the bottom surface of the sintered body thus obtained to obtain an orthodontic member (bracket). The irregularities 61 were formed by shot blasting.
[0188]
This orthodontic member (bracket) is made of a Ti-based metal material, and is manufactured by LECO EC-12 (carbon analyzer), RO-116 (oxygen analyzer), TN-114 (nitrogen). As a result of elemental analysis by the analyzer of the analyzer, the amounts of C, O and N contained were C: 0.055 wt%, O: 0.42 wt% and N: 0.03 wt%, respectively.
[0189]
Moreover, the porosity (measured by Archimedes method) of the orthodontic member (bracket) was 3 vol%.
[0249]
<Evaluation of quality and characteristics>
The orthodontic members (brackets) obtained in the above examples were evaluated for quality and characteristics as shown below.
[0250]
1. quality
The brackets obtained in Example 1 were cut in multiple directions, and their cut end faces were visually observed to check for the presence of sintered defects. As a result, the bracket according to Example 1 was of good quality with no sintering defects.
[0251]
2. Dimensional error
For the 10 brackets obtained in Example 1, the maximum width of the engaging portion 3 and the width of the slot 4 were measured, and the dimensional error (dimensional variation) was examined. The dimensional error was ± 0.5%. It was the following. Thereby, it was confirmed that the thing of Example 1 has high dimensional accuracy.
[0252]
3. Mechanical strength (bending strength)
The bending strength of the bracket obtained in Example 1 was measured in accordance with Japan Powder Metallurgy Industry Association Standard JPMA M 09-1992.
[0253]
4). hardness
Based on JIS Z 2244, the Vickers hardness Hv of the surface of the engaging part 3 in the sintered compact of the bracket obtained in Example 1 was measured (load 500 g).
[0254]
5). Metal component elution (biocompatibility)
The bracket obtained in Example 1 was immersed in a 0.05% hydrochloric acid solution for 100 days, and then the metal ion concentration in this solution was analyzed and quantified by a plasma emission analyzer. The smaller the elution amount, the better the biocompatibility.
[0255]
6). Aesthetics
The difference between the glossiness of the surface and the color tone of the teeth was judged visually. The evaluation was made in four grades of ◎, ○, Δ, and × in order from the one with less gloss (= high aesthetics). Moreover, the thing with little difference with the color tone of a tooth was also evaluated as having high aesthetics.
[0256]
The mechanical strength (bending strength), hardness, metal component elution amount (biocompatibility) and aesthetic results are shown in Table 1 below.
[0257]
[Table 1]

[0258]
As shown in Table 1, the bracket obtained in Example 1 has high mechanical strength (bending strength) and surface hardness. Moreover, the bracket obtained in Example 1 is excellent in biocompatibility and aesthetics.
[0259]
【The invention's effect】
As described above, according to the present invention, even a complicated shape can be easily manufactured, and a high-density (low porosity) orthodontic member having high dimensional accuracy can be obtained. And since it is by extrusion molding, productivity is high and it is suitable for mass production of an orthodontic member.
[0260]
Moreover, an orthodontic member can be manufactured also about the hard material etc. which were conventionally difficult to process, and the expansion of the function and shape (design) of the orthodontic member can be aimed at.
[0261]
In addition, by adjusting the cutting length, various types of orthodontic members can be easily manufactured, so that the orthodontic members can be supplied with excellent productivity and at low cost.
[0262]
Further, in the case of a material composed of a Ti-based metal material, the content of C, O, and N in the sintered body can be reduced, so that an orthodontic member having high ductility (toughness) can be obtained.
[Brief description of the drawings]
FIG. 1 is a process chart showing a first embodiment of a method for producing an orthodontic member of the present invention.
FIG. 2 is a perspective view showing a configuration example of an orthodontic member (orthodontic bracket) according to the present invention.
FIG. 3 is a bottom view of the orthodontic member shown in FIG. 2;
FIG. 4 is a perspective view showing a configuration example of a long molded body obtained in the manufacturing process of the manufacturing method of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Orthodontic bracket, 2 ... Base part, 3 ... Engagement part (tie wing), 31-34 ... Projection part, 35, 36 ... Projection, 4, 5 ... Slot (groove), 6 ... Bottom (back surface) ), 61... Concavity and convexity, 7, 8... Groove, 10.

Claims (1)

Using a compound containing raw material powder, a molding step of obtaining a long shaped body having a cross-sectional shape corresponding to the cross-sectional shape of the orthodontic member by extrusion molding,
Forming a groove corresponding to the slot in the long shaped body by machining using a dicing machine;
A cutting step of cutting the long molded body in which the groove is formed into a predetermined length;
A degreasing step of performing a degreasing process on the cut molded body to obtain a degreased body;
And a sintering step of obtaining a sintered body by sintering the degreased body subjected to the degreasing treatment.

Images