JPH0297604A - Manufacture of sintered compact - Google Patents
Manufacture of sintered compactInfo
- Publication number
- JPH0297604A JPH0297604A JP24952588A JP24952588A JPH0297604A JP H0297604 A JPH0297604 A JP H0297604A JP 24952588 A JP24952588 A JP 24952588A JP 24952588 A JP24952588 A JP 24952588A JP H0297604 A JPH0297604 A JP H0297604A
- Authority
- JP
- Japan
- Prior art keywords
- liquid
- sintering
- slurry
- powder
- density
- 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
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 7
- 239000007788 liquid Substances 0.000 claims abstract description 54
- 238000005245 sintering Methods 0.000 claims abstract description 46
- 239000000843 powder Substances 0.000 claims abstract description 43
- 239000002002 slurry Substances 0.000 claims abstract description 29
- 239000011230 binding agent Substances 0.000 claims abstract description 10
- 238000000034 method Methods 0.000 abstract description 9
- 101100356682 Caenorhabditis elegans rho-1 gene Proteins 0.000 abstract 2
- 101100087528 Mus musculus Rhoj gene Proteins 0.000 abstract 2
- 101150111584 RHOA gene Proteins 0.000 abstract 2
- 238000007599 discharging Methods 0.000 abstract 2
- 238000000465 moulding Methods 0.000 description 5
- 239000002184 metal Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000012856 packing Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000004925 Acrylic resin Substances 0.000 description 1
- 229920000178 Acrylic resin Polymers 0.000 description 1
- -1 and for example Substances 0.000 description 1
- 125000002915 carbonyl group Chemical group [*:2]C([*:1])=O 0.000 description 1
- 229920002301 cellulose acetate Polymers 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000009689 gas atomisation Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229920001187 thermosetting polymer Polymers 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Producing Shaped Articles From Materials (AREA)
- Powder Metallurgy (AREA)
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明は、焼結成形物の製造方法に関し、特に寸法、精
度を厳しく要求されるものを焼結成形するのに適したも
のである。DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for manufacturing sintered products, and is particularly suitable for sintering products whose dimensions and precision are strictly required.
（従来の技術）
焼結成形物の製造方法としては、特開昭６１−１０４０
５号公報にて開示された技術がある。(Prior art) A method for manufacturing sintered molded products is disclosed in Japanese Patent Application Laid-Open No. 1040-1983.
There is a technique disclosed in Publication No. 5.
これは、焼結用粉末とバインダーとを液体を介して混合
してスラリーとし、このスラリーを液体流出口を有する
成形型内で加圧することで、その液体流出口から液体を
流出させて成形体とし、この成形体を焼結して所望形状
の焼結成形物とするものである。This method involves mixing sintering powder and a binder via a liquid to form a slurry, pressurizing this slurry in a mold that has a liquid outlet, and allowing the liquid to flow out from the liquid outlet to form a molded product. This molded body is then sintered to form a sintered molded product of a desired shape.
これにより、焼結前の加圧成形を低圧で行なうことがで
きるものとし、また、スラリーの脱液工程をその加圧成
形と同時に行うことで成形時間の短縮を図るものである
。Thereby, pressure forming before sintering can be performed at low pressure, and the molding time can be shortened by performing the step of removing liquid from the slurry at the same time as the pressure forming.
（発明が解決しようとする課題）
焼結に際しては体積収縮を生じることから、焼結前の加
圧成形体は、その収縮を見込んだ分だけ大きな寸法とさ
れている。すなわち、その焼結収縮率の予想の正確さが
製品の寸法精度を支配する要因となる。(Problems to be Solved by the Invention) Since volumetric shrinkage occurs during sintering, the size of the press-molded body before sintering is made larger to account for the shrinkage. In other words, the accuracy of predicting the sintering shrinkage rate is a factor that governs the dimensional accuracy of the product.
しかし、上記従来の方法では、収縮率の平均値の予想は
予め実験等を行うことで正確に行えるが、場所による収
縮率のバラツキは予想できず、厳しい寸法精度を要求さ
れる場合には適用困難なものであった。また、製品の機
械的特性にもバラツキを生じるものであった。However, with the conventional method described above, although the average value of shrinkage rate can be accurately predicted by conducting experiments in advance, it is not possible to predict variations in shrinkage rate depending on location, and it is not suitable for cases where strict dimensional accuracy is required. It was difficult. Furthermore, the mechanical properties of the products also varied.
本発明は上記課題を解決することを目的とする。The present invention aims to solve the above problems.
（課題を解決するための手段）
本発明の特徴とするところは、焼結用粉末とバインダー
とを液体を介して混合してスラリーとし、このスラリー
を液体流出口を有する成形型内で加圧することで、その
液体流出口から液体を流出させて成形体とし、この成形
体を焼結して所望形状の焼結成形物とするに際し、スラ
リーに占める液体の割合をｖｓ、焼結用粉末に膜状に吸
着した液体の膜厚をＴ、焼結用粉末のみかけ密度、タッ
プ密度、真密度、比表面積をそれぞれｒａ、■ｔ、ｆｏ
、Ｓとした場合に、
とする点にある。(Means for Solving the Problems) The present invention is characterized in that a sintering powder and a binder are mixed via a liquid to form a slurry, and this slurry is pressurized in a mold having a liquid outlet. This allows the liquid to flow out from the liquid outlet to form a molded body, and when this molded body is sintered to form a sintered molded product of a desired shape, the proportion of the liquid in the slurry vs. the sintering powder can be changed. The film thickness of the liquid adsorbed in a film is T, and the apparent density, tapped density, true density, and specific surface area of the sintering powder are ra, ■t, and fo, respectively.
, S, there is a point where .
（作 用） 本発明は以下の考察に基づく。(for production) The present invention is based on the following considerations.
焼結前の加圧成形体の焼結時における体積収縮率の場所
による不均一の要因として、その加圧成形体の場所によ
る密度の不均一がある。One of the causes of non-uniformity in the volumetric shrinkage rate depending on location during sintering of a press-formed body before sintering is the non-uniformity in density depending on the location of the press-formed body.
そのような焼結前の加圧成形体の密度不均一の原因は、
第１図に示すように、スラリー１を成形型２内で加圧し
、成形型２の液体流出口からスラリー１中の液体３を流
出させる際に、焼結用粉末４のうちの小径軽量のものが
、液体と共に流動し易いことから液体流出口に偏在して
しまうことによる。The cause of such non-uniform density of the pressed body before sintering is
As shown in FIG. 1, when the slurry 1 is pressurized in the mold 2 and the liquid 3 in the slurry 1 is flowed out from the liquid outlet of the mold 2, a small diameter and lightweight powder of the sintering powder 4 is used. This is because substances tend to flow together with the liquid and are unevenly distributed at the liquid outlet.
よって、スラリー１を加圧して液体を流出させる際に、
焼結用粉末４の流動を抑制すれば、加圧前のスラリー中
の粉末分布はランダムであることから、均一な密度の加
圧成形体を得られ、それにより、焼結時における体積収
縮の場所による不均一をなくすことができると考えられ
る。Therefore, when pressurizing slurry 1 and causing the liquid to flow out,
If the flow of the sintering powder 4 is suppressed, the powder distribution in the slurry before pressing is random, so a pressed compact with a uniform density can be obtained, thereby reducing the volumetric shrinkage during sintering. It is thought that it is possible to eliminate unevenness depending on location.
そして、スラリー１中の液体の占める割合を可及的に小
さくすれば、第２図に示すように、焼結用粉末４は互い
の流動を拘束し、また、バインダーによる流動の拘束も
最も効果的となり、粉末分布を均一なものとできる。If the proportion of the liquid in the slurry 1 is made as small as possible, the sintering powders 4 will restrain their mutual flow, as shown in FIG. This makes it possible to achieve a uniform powder distribution.
具体的には、スラリー１中の液体は、第３図に示すよう
に、焼結用粉末４に膜状に吸着する膜状液体５と、この
膜状液体５以外の自由液体６とに分けられる。そして、
第４図に示すように、焼結用粉末４が膜状液体５を介し
て接触する状態となれば、互いの流動を規制する。よっ
て、焼結用粉末４の間の空間を可及的小さくすることが
、スラリー１中の液体の占める割合を可及的に小さくす
ることになる。Specifically, as shown in FIG. 3, the liquid in the slurry 1 is divided into a film-like liquid 5 that is adsorbed to the sintering powder 4 in a film-like manner and a free liquid 6 other than this film-like liquid 5. It will be done. and,
As shown in FIG. 4, when the sintering powders 4 come into contact with each other via the film-like liquid 5, their mutual flow is restricted. Therefore, by making the space between the sintering powders 4 as small as possible, the proportion of the liquid in the slurry 1 will be made as small as possible.
そして、加圧前の焼結用粉末４のみかけ密度をｆａ、真
密度を／’ｏとすれば、加圧前に焼結用粉末４の間に生
じる空間の全体積に占める割合は、１−７’ａ ／ ｆ
ｏで表され、これが、自由液体６の加圧前における最小
量となり、これより多ければ焼結用粉末は流動すること
になる。また、焼結用粉末４の比表面積Ｓ、膜状液体５
の厚さをＴとすれば、膜状液体５の最小比体積はＴ−３
となる。If the apparent density of the sintering powder 4 before pressurization is fa and the true density is /'o, then the proportion of the space created between the sintering powders 4 before pressurization in the total volume is 1 -7'a/f
This is the minimum amount of free liquid 6 before pressurization, and if the amount is larger than this, the sintering powder will flow. In addition, the specific surface area S of the sintering powder 4, the film-like liquid 5
If the thickness of is T, the minimum specific volume of the film-like liquid 5 is T-3
becomes.
よって、加圧前における焼結用粉末４の間に生じる空間
が、全体積に占める割合を、
で表した場合、スラリー１に占める液体の割合Ｖｓをこ
れより小さくすれば、焼結用粉末４が流動することはな
い。Therefore, if the proportion of the space created between the sintering powders 4 before pressurization to the total volume is expressed as follows, then if the proportion Vs of the liquid in the slurry 1 is made smaller than this, the sintering powders 4 never flows.
一方、加圧後の最密充填状態での焼結用粉末４のタップ
密度をｒｔとすると、最密充填時における焼結用粉末４
の間に生じる空間が全体積に占める割合は、１−ｆ’ｔ
／ｆ’ｏで表され、これが、自由液体３の粉末最密充填
時における最小量となる。On the other hand, if the tap density of the sintering powder 4 in the closest packed state after pressurization is rt, then the sintering powder 4 in the closest packing state
The ratio of the space created between them to the total volume is 1-f't
/f'o, which is the minimum amount of free liquid 3 when the powder is most closely packed.
また、粉末最密充填時における膜状液体の最小比体積は
加圧前と同様にＴ−３である。よって、粉末最密充填時
における焼結用粉末４の間に生じる空間が、全体積に占
める割合を、
で表した場合、スラリー１に占める液体の割合ＶＳをこ
れより大きくすれば、焼結用粉末４とツマインダーとは
液体を介してスラリーの状態を保持できる。Further, the minimum specific volume of the film-like liquid when the powder is most closely packed is T-3 as before pressurization. Therefore, if the ratio of the space created between the sintering powders 4 to the total volume during the closest packing of the powder is expressed as follows, then if the ratio VS of the liquid to the slurry 1 is made larger than this, the sintering powder 4 The powder 4 and the binder can maintain a slurry state through the liquid.
（実施例） 以下の表に示す条件で、金型を焼結成形した。(Example) A mold was sintered and molded under the conditions shown in the table below.
次 葉
この表の中で、ａは金属粉末の粒径 、Ｖａｉｎは前記
■式で計算した値、Ｖｍａｘは前記１式で計算した値を
示す。なお、液体の膜圧Ｔは１０−’ｕ＋＊とした。In this table, a is the particle size of the metal powder, Vain is the value calculated using the above equation (2), and Vmax is the value calculated using the above equation 1. Note that the film pressure T of the liquid was 10-'u++.
成形形状のＡは第５図のマスターモデル７を用いて金型
を成形し、成形形状のＢは第６図のマスターモデル７を
用いて金型を成形したことを示す。Molding shape A indicates that the mold was molded using the master model 7 in FIG. 5, and molding shape B indicates that the mold was molded using the master model 7 in FIG. 6.
焼結時間の分子は最高温度での保持時間を示し、分母は
全工程時間を示す。The numerator of the sintering time indicates the holding time at the highest temperature and the denominator indicates the total process time.
寸法収縮差は、焼結後に金型の高さや径等の各部の寸法
収縮率を計測し、その最大値と最小値との差を示す。The dimensional shrinkage difference measures the dimensional shrinkage rate of each part such as the height and diameter of the mold after sintering, and indicates the difference between the maximum value and the minimum value.
また、第７図に示す成形型２を用いた。この成形型２は
、外枠８と、この外枠８に内装される前記マスターモデ
ル７と、加圧プランジ中９とで構成される。そして、外
枠８は紙面直交方向に並列する複数の分割体により成形
され、各分割体の対向面間がスリットとされ、そのスリ
ットが液体流出口とされている。また、外枠８の内型面
と加圧プランジャ９との間もスリット状の液体流出口と
されている。Further, a mold 2 shown in FIG. 7 was used. The mold 2 is composed of an outer frame 8, the master model 7 housed in the outer frame 8, and a pressure plunger 9. The outer frame 8 is formed by a plurality of divided bodies arranged in parallel in a direction perpendicular to the plane of the paper, and a slit is formed between the opposing surfaces of each divided body, and the slit is used as a liquid outlet. Further, a slit-shaped liquid outlet is also formed between the inner mold surface of the outer frame 8 and the pressurizing plunger 9.
上記外枠８に、カーボニル法やガスアトマイズ法によっ
て製造した金属粉末とバインダーとを液体を介して混合
したスラリー１を充填し、加圧プランジャ９により１５
０ ｋｇ ／ｄ で加圧してスリットから液体を流出
させた。なお、成形型２は９゜°に予熱した。そして、
表中の焼結条件で焼結後に離型し、乾燥炉で乾燥した。The outer frame 8 is filled with a slurry 1 in which metal powder produced by the carbonyl method or gas atomization method and a binder are mixed through a liquid, and the slurry 1 is
A pressure of 0 kg/d was applied to cause the liquid to flow out from the slit. Note that the mold 2 was preheated to 9°. and,
After sintering under the sintering conditions shown in the table, the mold was released and dried in a drying oven.
以上の結果から明らかなように、Ｖｓを本発明に基づき
定めることで、寸法収縮差を小さくすることができる。As is clear from the above results, by determining Vs based on the present invention, the difference in dimensional shrinkage can be reduced.
すなわち、場所による焼結収縮率のバラツキを小さくし
、高精度の製品を得ることができる。That is, it is possible to reduce the variation in sintering shrinkage rate depending on location and obtain a highly accurate product.
なお、焼結用粉末としては金属粉末に限らず、例えばセ
ラミック粉末を用いてもよく、焼結成形品は金型に限定
されるものではない。Note that the sintering powder is not limited to metal powder, and for example, ceramic powder may be used, and the sintered molded product is not limited to a mold.
バインダーとしては、無機バインダーやアクリル樹脂系
、酢酸セルロース性、熱硬化樹脂系の有機バインダーを
用いることができる。As the binder, an inorganic binder or an acrylic resin-based, cellulose acetate-based, or thermosetting resin-based organic binder can be used.
スラリーとするための液体としては水や有機溶剤を用い
ることができる。Water or an organic solvent can be used as the liquid to form the slurry.
成形型２の液体流出口をスリットとしたときは、そのス
リット幅Ｗは粉末平均粒径Ｊ（μｍ）に対し、１０μ■
≦Ｗ≦３ａとするのがよい。１０μｍ以下とするのは工
業的に困難である。３ａを越えると粉末流出により成形
困難となるからである。もっとも液体流出口の形状はス
リットに限定されず、例えば、成形型をポーラスを有す
る材質で形成してもよい。When the liquid outlet of the mold 2 is a slit, the slit width W is 10 μm with respect to the powder average particle diameter J (μm).
It is preferable that ≦W≦3a. It is industrially difficult to reduce the thickness to 10 μm or less. This is because if it exceeds 3a, molding becomes difficult due to powder outflow. However, the shape of the liquid outlet is not limited to a slit; for example, the mold may be made of a porous material.
（発明の効果）
本発明によれば、焼結成形物を製造するに際し、焼結収
縮率の不均一を小さくすることができ、寸法精度が高く
、機械的特性も均一な製品を得ることができる。(Effects of the Invention) According to the present invention, when manufacturing a sintered product, it is possible to reduce non-uniformity in sintering shrinkage rate, and to obtain a product with high dimensional accuracy and uniform mechanical properties. can.
第１図及び第２図はそれぞれ相異なったスラリーの中の
焼結用粉末の動きを説明する図、第３図及び第４図はそ
れぞれ相異なったスラリーの状態を示す図、第５図及び
第６図はそれぞれ相異なったマスターモデルの断面図、
第７図は成形型の断面図である。
１・・・スラリー、２・・・成形型、３・・・液体、４
・・・焼結用粉末。
特許出願
株式会社神戸製鋼所
第３図
第４図
第５図
第７
＠１図Figures 1 and 2 are diagrams explaining the movement of sintering powder in different slurries, Figures 3 and 4 are diagrams showing different states of slurry, Figures 5 and Figure 6 is a cross-sectional view of different master models,
FIG. 7 is a sectional view of the mold. 1... Slurry, 2... Molding mold, 3... Liquid, 4
... Powder for sintering. Patent application Kobe Steel, Ltd. Figure 3 Figure 4 Figure 5 Figure 7 @Figure 1
Claims (1)
てスラリーとし、このスラリーを液体流出口を有する成
形型内で加圧することで、その液体流出口から液体を流
出させて成形体とし、この成形体を焼結して所望形状の
焼結成形物とするに際し、スラリーに占める液体の割合
を（Ｖｓ）、焼結用粉末に膜状に吸着した液体の膜厚を
（Ｔ）、焼結用粉末のみかけ密度、タップ密度、真密度
、比表面積をそれぞれ（■ａ）（■ｔ）（■ｏ）（Ｓ）
とした場合に、 １−■ｔ／［■ｏ＋■ｔ・Ｔ・Ｓ］≦Ｖｓ≦１−■ａ／
［■ｏ＋■ａ・Ｔ・Ｓ］とすることを特徴とする焼結成
形物の製造方法。(1) Sintering powder and binder are mixed through a liquid to form a slurry, and this slurry is pressurized in a mold having a liquid outlet, so that the liquid flows out from the liquid outlet to form a molded product. When this compact is sintered to form a sintered product of a desired shape, the proportion of the liquid in the slurry is (Vs), and the film thickness of the liquid adsorbed in the form of a film on the sintering powder is (T). , the apparent density, tap density, true density, and specific surface area of the sintering powder are (■a) (■t) (■o) (S), respectively.
In this case, 1-■t/[■o+■t・T・S]≦Vs≦1−■a/
A method for producing a sintered molded article, characterized in that [■o+■a・T・S].
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24952588A JPH0297604A (en) | 1988-10-01 | 1988-10-01 | Manufacture of sintered compact |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24952588A JPH0297604A (en) | 1988-10-01 | 1988-10-01 | Manufacture of sintered compact |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0297604A true JPH0297604A (en) | 1990-04-10 |
Family
ID=17194278
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP24952588A Pending JPH0297604A (en) | 1988-10-01 | 1988-10-01 | Manufacture of sintered compact |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0297604A (en) |
-
1988
- 1988-10-01 JP JP24952588A patent/JPH0297604A/en active Pending
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