JPH0852713A - Ceramics spherical molded body - Google Patents
Ceramics spherical molded bodyInfo
- Publication number
- JPH0852713A JPH0852713A JP6190786A JP19078694A JPH0852713A JP H0852713 A JPH0852713 A JP H0852713A JP 6190786 A JP6190786 A JP 6190786A JP 19078694 A JP19078694 A JP 19078694A JP H0852713 A JPH0852713 A JP H0852713A
- Authority
- JP
- Japan
- Prior art keywords
- slurry
- molded body
- ceramics
- spherical
- spherical molded
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、ボールべアリング、特
にＯＡ機器などに用いられるミニチュアボールべアリン
グ及びボールミル等に利用されるセラミックボールに関
する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ball bearing, particularly a miniature ball bearing used in OA equipment and a ceramic ball used in a ball mill.
【０００２】[0002]
【従来技術及びその問題点】セラミックスは軽量でかつ
耐摩耗性等の機械的性質に優れるため、軸受け用ボール
べアリング等の用途に適している。軸受けには様々な用
途があるが、近年、ＯＡ機器等の発展とともにミニチュ
アボールべアリングの需要が拡大してきた。このため高
精度で高品質のセラミックボールを安価に製造する方法
が求められている。従来、比較的大きなセラミックボー
ルの製造には金型プレス成形法、ＣＩＰ(Cold Isostati
c Pressing)成形法、鋳込み成形法、射出成形法、転動
造粒法等が用いられてきた。しかし、金型プレス成形法
によって製造されるセラミックボールは、加圧方向が一
軸となるために成形体内部に密度差を生じやすい。ＣＩ
Ｐ成形法によれば、ゴム型の変形を制御することが難し
く、成形体の形状が真球から大きく逸脱する。転動造粒
法によれば、加圧操作を加えないため気孔等の欠陥を生
じやすく、その上、ほぼ完全な球形の成形体を得るのが
困難である。また、鋳込み成形法、射出成形法等で製造
されるセラミックボールには、鋳込み口に突起が形成さ
れたり、ゲート部に突起又はくぼみが形成され、さらに
乾燥工程又は脱脂工程を必要とするため生産性が悪い。
しかも、上述の何れの方法でも、直径が比較的小さいボ
ールを成形しようとすると、成形能率が非常に悪く、ま
た、球形にするための後加工が必要になり、コスト高に
なるという問題がある。2. Description of the Related Art Ceramics are lightweight and have excellent mechanical properties such as wear resistance, and are therefore suitable for applications such as ball bearings for bearings. Although bearings have various uses, the demand for miniature ball bearings has expanded in recent years with the development of OA equipment and the like. Therefore, there is a demand for a method of manufacturing a highly accurate and high quality ceramic ball at low cost. Conventionally, a die press molding method and CIP (Cold Isostati) have been used to manufacture relatively large ceramic balls.
c Pressing) molding method, casting molding method, injection molding method, tumbling granulation method and the like have been used. However, since the ceramic balls manufactured by the die press molding method have a uniaxial pressing direction, a density difference is likely to occur inside the molded body. CI
According to the P molding method, it is difficult to control the deformation of the rubber mold, and the shape of the molded body largely deviates from the true sphere. According to the tumbling granulation method, since pressure operation is not applied, defects such as pores are likely to occur, and it is difficult to obtain an almost perfect spherical shaped body. In addition, ceramic balls manufactured by the casting method, injection molding method, etc., have protrusions formed at the casting port, protrusions or depressions at the gate portion, and a drying step or a degreasing step is required, so production The sex is bad.
Moreover, in any of the above methods, when a ball having a relatively small diameter is to be formed, the forming efficiency is very poor, and post-processing for forming a spherical shape is required, resulting in a high cost. .
【０００３】[0003]
【発明の目的】本発明の目的は、上記問題点を解決する
ためになされたものであり、高能率で製造できる直径１
０ｍｍ以下の比較的小さな真球状成形体を提供すること
を目的とする。SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned problems, and the diameter 1 which can be manufactured with high efficiency.
It is an object of the present invention to provide a relatively small spherical molded body having a size of 0 mm or less.
【０００４】[0004]
【問題を解決するための手段】本発明は、セラミック粉
末及びポリマーからなるセラミック球状成形体であっ
て、球径に対する真円度の割合が１％以下の真円度を有
することを特徴とするセラミック球状成形体に関するも
のである。本発明におけるセラミック粉末としては、窒
化ケイ素、炭化ケイ素、窒化ホウ素、ホウ化チタン、炭
化ホウ素、マグネシア、アルミナ、イットリア、ジルコ
ニア、シリカ、ムライト、スピネル等種々のセラミック
スを挙げることができる。また、本発明のポリマーは、
セラミック球状成形体が形成される時に重合可能なモノ
マーが重合することにより生成するポリマーである。セ
ラミック粉末とポリマーの割合は、セラミック粉末１０
０重量部に対して、ポリマーが１〜１０重量部が望まし
い。本発明において、セラミック球状成形体とは、セラ
ミック粉末を成形して得られる、いわゆるグリーン成形
体を意味し、かつ成形後に表面加工を一切施していない
ものである。DISCLOSURE OF THE INVENTION The present invention is a ceramic spherical molded article comprising a ceramic powder and a polymer, and is characterized by having a circularity ratio of 1% or less to the spherical diameter. The present invention relates to a ceramic spherical molded body. Examples of the ceramic powder in the present invention include various ceramics such as silicon nitride, silicon carbide, boron nitride, titanium boride, boron carbide, magnesia, alumina, yttria, zirconia, silica, mullite and spinel. Further, the polymer of the present invention,
It is a polymer produced by polymerizing a polymerizable monomer when a ceramic spherical molded body is formed. The ratio of ceramic powder to polymer is 10
The amount of the polymer is preferably 1 to 10 parts by weight with respect to 0 parts by weight. In the present invention, the ceramic spherical molded body means a so-called green molded body obtained by molding ceramic powder, and does not undergo any surface treatment after molding.
【０００５】本発明のセラミック球状成形体は、セラミ
ック粉末、重合可能なモノマー及び分散溶媒からなるス
ラリーを、これと混和しない液体中に分散させ、表面張
力によりスラリーを球状にした状態でモノマーを重合さ
せて、スラリーをゲル化することにより得られる。重合
可能なモノマーとしては、ラジカル重合する一官能性モ
ノマーが挙げられる。モノマーは、セラミック粉末１０
０重量部に対して、通常１〜１０重量部添加する。ま
た、成形体の強度を上げるために、架橋剤として二官能
性モノマーを併用することが好ましい。一官能性モノマ
ー、二官能性モノマーとしては、それぞれアクリルアミ
ド、Ｎ，Ｎ’−メチレンビスアクリルアミド等の官能基
としてビニル基やアリル基を含む水溶性モノマーが挙げ
られる。分散溶媒としては、モノマーが可溶な溶媒であ
ればよく、水や有機溶媒が用いられる。さらに、低粘度
で高濃度のスラリー調製を可能にするために、ポリカル
ボン酸塩等の分散剤を添加することが好ましい。The ceramic spherical molded article of the present invention is obtained by dispersing a slurry consisting of ceramic powder, a polymerizable monomer and a dispersion solvent in a liquid immiscible with the slurry, and polymerizing the monomer in a state where the slurry is spherical due to surface tension. Then, it is obtained by gelling the slurry. Examples of the polymerizable monomer include a monofunctional monomer that undergoes radical polymerization. Monomer is ceramic powder 10
Usually, 1 to 10 parts by weight is added to 0 parts by weight. Further, in order to increase the strength of the molded product, it is preferable to use a bifunctional monomer in combination as a crosslinking agent. Examples of the monofunctional monomer and the bifunctional monomer include water-soluble monomers having a vinyl group or an allyl group as a functional group such as acrylamide and N, N′-methylenebisacrylamide. The dispersion solvent may be a solvent in which the monomer is soluble, and water or an organic solvent is used. Further, it is preferable to add a dispersant such as a polycarboxylic acid salt in order to enable preparation of a slurry having a low viscosity and a high concentration.
【０００６】本発明においては、まずセラミック粉末、
重合可能なモノマー及び分散溶媒をボールミル混合して
スラリーを調製する。乾燥収縮による寸法変化を極小に
するため、スラリーの流動する範囲内でスラリー濃度を
可及的に大きくすることが望ましい。次に、重合開始剤
を添加した後、スラリー中の気泡を除去するために、ス
ラリーの減圧処理を行う。重合開始剤としては、水溶性
の過硫酸アンモニウム又は有機溶媒可溶性のアゾビスイ
ソブチロニトリル（ＡＩＢＮ）等を用いることができ
る。次いで、前記スラリーをこれと混和しない液体中に
分散させ、表面張力によりスラリーを球状にした状態で
モノマーを重合させて、スラリーをゲル化することによ
り良好な真円度を有するセラミック球状成形体を得る。
ゲル化して得られた成形体は強度が大きく、液体からの
分離、洗浄、乾燥等の操作後も維持される。スラリーと
混和しない液体としては、比較的沸点が高く、モノマー
の重合を阻害しないものを用いることができ、水溶媒ス
ラリーの場合には、ブチルべンジルフタレート（ＢＢ
Ｐ）等の有機溶媒が用いられる。In the present invention, first, ceramic powder,
The polymerizable monomer and the dispersion solvent are ball mill mixed to prepare a slurry. In order to minimize the dimensional change due to drying shrinkage, it is desirable to increase the slurry concentration within the range where the slurry flows. Next, after the polymerization initiator is added, the slurry is depressurized in order to remove bubbles in the slurry. As the polymerization initiator, water-soluble ammonium persulfate or organic solvent-soluble azobisisobutyronitrile (AIBN) or the like can be used. Next, the slurry is dispersed in a liquid that is immiscible with the slurry, and the monomer is polymerized in a state where the slurry is spherical due to surface tension, and the slurry is gelled to obtain a ceramic spherical molded body having good roundness. obtain.
The molded product obtained by gelling has high strength and is maintained even after operations such as separation from liquid, washing, and drying. As the liquid that is immiscible with the slurry, one that has a relatively high boiling point and does not hinder the polymerization of the monomer can be used. In the case of the aqueous solvent slurry, butyl benzyl phthalate (BB
An organic solvent such as P) is used.
【０００７】モノマーの重合は、例えば定量ポンプで供
給したスラリーをノズルから一定速度で液体中に吐出し
ながら行う。ノズル径や供給速度を制御することにより
液滴の大きさを調節することができる。液体の温度を上
げると重合反応が促進され、固化時間の短縮ひいては装
置の小型化が可能となる。また、液体中に重合開始剤を
溶解させることによっても、重合を促進することができ
る。液体中に吐出されたスラリー液滴は、表面張力の作
用により球形に近づく。液滴が固化して得られる成形体
の真円度を向上させるためには、液滴が液体中を移動す
る際に受ける外力の作用を低減する必要がある。発明者
らは、液体の温度及び粘度等を変化させて液滴の落下速
度を調節した結果、スラリー液滴が液体から受ける抵抗
を低減できることを見出した。このような方法で製造さ
れたセラミック球状成形体は真円度が良好であるため、
軸受け用ボールとして用いる場合に必要となる精密研磨
工程において、研磨定盤を傷めることがなく、また、研
磨量が削減できるので、製造コストが安価になる。な
お、本発明における真円度とは、セラミック球状成形体
の形状誤差の最小値から最大値までの偏差を表す。Polymerization of the monomer is carried out, for example, by discharging the slurry supplied by a metering pump into the liquid at a constant rate from a nozzle. The size of the droplet can be adjusted by controlling the nozzle diameter and the supply speed. When the temperature of the liquid is raised, the polymerization reaction is promoted, the solidification time can be shortened, and the apparatus can be downsized. The polymerization can also be promoted by dissolving the polymerization initiator in the liquid. The slurry droplets ejected into the liquid become spherical due to the effect of surface tension. In order to improve the roundness of the molded product obtained by solidifying the droplets, it is necessary to reduce the effect of an external force applied when the droplets move in the liquid. The inventors have found that the resistance of the slurry droplets to the liquid can be reduced as a result of adjusting the drop velocity of the droplets by changing the temperature and viscosity of the liquid. Since the ceramic spherical molded body manufactured by such a method has a good roundness,
In the precision polishing step required when using as a bearing ball, the polishing platen is not damaged and the polishing amount can be reduced, so that the manufacturing cost is reduced. The roundness in the present invention represents the deviation from the minimum value to the maximum value of the shape error of the ceramic spherical molded body.
【０００８】[0008]
【実施例】以下に、本発明の実施例を説明する。 実施例１ 原料粉末として粒径０．２μｍの窒化ケイ素粉末１００
重量部、焼結助剤としてアルミナ粉末３重量部及びイッ
トリア粉末６重量部、分散剤としてポリアクリル酸アン
モニウム塩０．３重量部、モノマーとしてアクリルアミ
ド３．６重量部、架橋剤としてＮ，Ｎ’−メチレンビス
アクリルアミド０．４重量部を、溶媒として水を用い、
４０時間ボールミル混合してスラリーを調製した。この
スラリーを１００ｇ採取し、重合開始剤として５ｗｔ％
過硫酸アンモニウム水溶液０．１ｍｌを添加し、減圧脱
泡処理を行った。次に間歇型定量ポンプを用いて、スラ
リーをこれと混和しない液体中にノズルから吐出、滴下
した。液体は、ＢＢＰ１００重量部に、重合開始剤とし
てＡＩＢＮ１〜６重量部、増粘剤としてバインドセラム
ＳＡ５３１（三井東圧（株）製）２０〜１００重量部を
溶解して調製した。この液体を内径２０ｍｍの一端を封
じたガラス管に装填し、外部から加熱することにより系
の温度を７０〜９５℃に調節した。増粘剤添加量及び系
の温度を変化させることにより、表１に示すように落下
速度を調節した。得られた成形体を乾燥した後、球径及
び真円度を測定した結果を表１に示す。EXAMPLES Examples of the present invention will be described below. Example 1 Silicon nitride powder 100 having a particle size of 0.2 μm as a raw material powder
Parts by weight, 3 parts by weight of alumina powder as a sintering aid and 6 parts by weight of yttria powder, 0.3 part by weight of polyacrylic acid ammonium salt as a dispersant, 3.6 parts by weight of acrylamide as a monomer, and N, N 'as a crosslinking agent. -0.4 parts by weight of methylenebisacrylamide, water as solvent,
A slurry was prepared by mixing with a ball mill for 40 hours. 100 g of this slurry was sampled, and 5 wt% as a polymerization initiator
0.1 ml of an aqueous solution of ammonium persulfate was added, and defoaming treatment under reduced pressure was performed. Next, using an intermittent metering pump, the slurry was discharged and dropped from a nozzle into a liquid that was immiscible with the slurry. The liquid was prepared by dissolving 1 to 6 parts by weight of AIBN as a polymerization initiator and 20 to 100 parts by weight of Bind Serum SA531 (manufactured by Mitsui Toatsu Co., Ltd.) as a thickener in 100 parts by weight of BBP. This liquid was loaded into a glass tube with one end having an inner diameter of 20 mm sealed, and the temperature of the system was adjusted to 70 to 95 ° C. by heating from the outside. By changing the addition amount of the thickener and the temperature of the system, the falling speed was adjusted as shown in Table 1. Table 1 shows the results of measuring the spherical diameter and the roundness after drying the obtained molded body.
【０００９】比較例１ 原料粉末として粒径０．２μｍの窒化ケイ素粉末１００
重量部、焼結助剤としてアルミナ粉末３重量部及びイッ
トリア粉末６重量部、分散剤としてポリアクリル酸アン
モニウム塩０．３重量部、結合剤としてポリビニルアル
コール１重量部を、溶媒として水を用い、４０時間ボー
ルミル混合してスラリーを調製した。これをスプレード
ライヤーを用い１５０℃で造粒した。造粒物をゴム型に
充填し、１５００ｋｇｆ／ｃｍ2の成形圧力でＣＩＰ成
形することにより球状成形体とした。実施例１と同様の
測定によって得られた球径及び真円度を表１に示す。Comparative Example 1 Silicon nitride powder 100 having a particle size of 0.2 μm as a raw material powder
Parts by weight, 3 parts by weight of alumina powder and 6 parts by weight of yttria powder as a sintering aid, 0.3 parts by weight of polyacrylic acid ammonium salt as a dispersant, 1 part by weight of polyvinyl alcohol as a binder, and water as a solvent, A slurry was prepared by mixing with a ball mill for 40 hours. This was granulated at 150 ° C using a spray dryer. The granulated product was filled in a rubber mold and subjected to CIP molding at a molding pressure of 1500 kgf / cm 2 to obtain a spherical molded body. Table 1 shows the spherical diameter and roundness obtained by the same measurement as in Example 1.
【００１０】[0010]
【表１】 [Table 1]
【００１１】[0011]
【発明の効果】本発明によれば、直径１０ｍｍ以下の真
円度の良好なセラミック球状成形体を安価に提供でき
る。According to the present invention, it is possible to inexpensively provide a ceramic spherical molded body having a diameter of 10 mm or less and good roundness.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 仁木 豊明 山口県宇部市大字小串1978番地の５ 宇部 興産株式会社宇部研究所内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toyoaki Niki 5 1978, Kobugushi, Ube City, Yamaguchi Prefecture Ube Kosan Co., Ltd. Ube Laboratory
Claims (1)
ラミック球状成形体であって、球径に対する真円度の割
合が１％以下の真円度を有することを特徴とするセラミ
ック球状成形体。1. A ceramic spherical molded body comprising a ceramic powder and a polymer, wherein the roundness to the spherical diameter has a circularity of 1% or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6190786A JPH0852713A (en) | 1994-08-12 | 1994-08-12 | Ceramics spherical molded body |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6190786A JPH0852713A (en) | 1994-08-12 | 1994-08-12 | Ceramics spherical molded body |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0852713A true JPH0852713A (en) | 1996-02-27 |
Family
ID=16263720
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6190786A Pending JPH0852713A (en) | 1994-08-12 | 1994-08-12 | Ceramics spherical molded body |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0852713A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001163673A (en) * | 1999-09-30 | 2001-06-19 | Toshiba Corp | Raw material for ceramic ball and method of producing ceramic ball |
| US7976941B2 (en) | 1999-08-31 | 2011-07-12 | Momentive Performance Materials Inc. | Boron nitride particles of spherical geometry and process for making thereof |
| JP2011153071A (en) * | 1999-09-30 | 2011-08-11 | Toshiba Corp | Material for ceramic ball |
| US9550888B2 (en) | 1999-08-31 | 2017-01-24 | Momentive Performance Materials Inc. | Low viscosity filler composition of boron nitride particles of spherical geometry and process |
-
1994
- 1994-08-12 JP JP6190786A patent/JPH0852713A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7976941B2 (en) | 1999-08-31 | 2011-07-12 | Momentive Performance Materials Inc. | Boron nitride particles of spherical geometry and process for making thereof |
| US9079801B2 (en) | 1999-08-31 | 2015-07-14 | Momentive Performance Materials Inc. | Boron nitride particles of spherical geometry and process of making |
| US9550888B2 (en) | 1999-08-31 | 2017-01-24 | Momentive Performance Materials Inc. | Low viscosity filler composition of boron nitride particles of spherical geometry and process |
| JP2001163673A (en) * | 1999-09-30 | 2001-06-19 | Toshiba Corp | Raw material for ceramic ball and method of producing ceramic ball |
| JP2011153071A (en) * | 1999-09-30 | 2011-08-11 | Toshiba Corp | Material for ceramic ball |
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