JPH04337003A - Pellet for injection molding - Google Patents
Pellet for injection moldingInfo
- Publication number
- JPH04337003A JPH04337003A JP13848191A JP13848191A JPH04337003A JP H04337003 A JPH04337003 A JP H04337003A JP 13848191 A JP13848191 A JP 13848191A JP 13848191 A JP13848191 A JP 13848191A JP H04337003 A JPH04337003 A JP H04337003A
- Authority
- JP
- Japan
- Prior art keywords
- injection molding
- sintering
- granules
- molding machine
- organic binder
- 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
- 238000001746 injection moulding Methods 0.000 title claims abstract description 34
- 239000008188 pellet Substances 0.000 title abstract 4
- 238000005245 sintering Methods 0.000 claims abstract description 22
- 239000011230 binding agent Substances 0.000 claims abstract description 21
- 239000000843 powder Substances 0.000 claims abstract description 18
- 238000004519 manufacturing process Methods 0.000 claims abstract description 9
- 239000000203 mixture Substances 0.000 claims abstract description 9
- 239000008187 granular material Substances 0.000 claims description 24
- 239000000047 product Substances 0.000 description 10
- 239000012467 final product Substances 0.000 description 8
- 238000002347 injection Methods 0.000 description 5
- 239000007924 injection Substances 0.000 description 5
- 238000000034 method Methods 0.000 description 5
- 238000000465 moulding Methods 0.000 description 4
- 238000001125 extrusion Methods 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 238000010008 shearing Methods 0.000 description 3
- 239000004372 Polyvinyl alcohol Substances 0.000 description 2
- 238000003780 insertion Methods 0.000 description 2
- 230000037431 insertion Effects 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000012188 paraffin wax Substances 0.000 description 2
- 235000019809 paraffin wax Nutrition 0.000 description 2
- 235000019271 petrolatum Nutrition 0.000 description 2
- 229920002451 polyvinyl alcohol Polymers 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 229920001684 low density polyethylene Polymers 0.000 description 1
- 239000004702 low-density polyethylene Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 229920000058 polyacrylate Polymers 0.000 description 1
- -1 polyethylene Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920000098 polyolefin Polymers 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 229920001169 thermoplastic Polymers 0.000 description 1
- 229920001187 thermosetting polymer Polymers 0.000 description 1
- 239000004634 thermosetting polymer Substances 0.000 description 1
Landscapes
- Powder Metallurgy (AREA)
Abstract
Description
【０００１】0001
【産業上の利用分野】本発明は、焼結用無機粉末と有機
バインダーとの混合物から成る射出成形用造粒物に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to granules for injection molding comprising a mixture of inorganic powder for sintering and an organic binder.
【０００２】0002
【従来技術】機械部品、電子部品等のみならず、多くの
分野で焼結体が使用されている。従来、このような焼結
製品は、焼結用の無機粉末と有機バインダーとの混合物
をプレス成形した後に焼結を行なうことにより製造され
ていたが、複雑な形状の製品を製造するには不適当であ
ることから、この様な製品の製造では、上記のプレス成
形に代わって射出成形が採用されるようになっている。BACKGROUND OF THE INVENTION Sintered bodies are used not only in mechanical parts and electronic parts, but also in many other fields. Conventionally, such sintered products have been manufactured by press-molding a mixture of inorganic powder and organic binder and then sintering it, but this method is not suitable for manufacturing products with complex shapes. Because of its suitability, injection molding is now being used instead of the above-mentioned press molding in the production of such products.
【０００３】上記射出成形は、焼結用の無機粉末と有機
バインダーとの混合物との造粒物を射出成形機内に投入
し、造粒物をシリンダー内で加熱して溶融し、シリンダ
ー内にあるスクリューによって金型内に射出することに
よって行なわれる。ここで得られた成形体は、脱バイン
ダー及び焼結を経て最終製品とされる。脱バインダーは
、成形体中に含まれる有機バインダーが完全に除去され
るまで行なわれるものであり、通常、成形体を加熱する
ことにより行なわれる。脱バインダーに引き続いて行な
われる焼結により収縮を生じるが、一般に得られる焼結
体の線収縮率は、焼結前の成形体に比較して、１５〜２
５％である。[0003] In the above injection molding, granules of a mixture of inorganic powder for sintering and an organic binder are put into an injection molding machine, the granules are heated and melted in a cylinder, and the granules are heated and melted in a cylinder. This is done by injecting into a mold using a screw. The molded body obtained here is made into a final product through debinding and sintering. Binder removal is carried out until the organic binder contained in the molded body is completely removed, and is usually carried out by heating the molded body. Shrinkage occurs due to sintering that is performed subsequent to binder removal, but the linear shrinkage rate of the sintered body generally obtained is 15 to 2, compared to the molded body before sintering.
It is 5%.
【０００４】上記のような射出成形を行なうに当たって
使用される造粒物は、一般に押出し造粒機などを用いて
焼結用の無機粉末と有機バインダーとの混合物を適当な
サイズに造粒することにより調製される。従来、この造
粒物のサイズはあまり考慮されておらず、射出成形機の
挿入口の径（通常、２０〜５０ｍｍ程度） より小さい
範囲内において可及的に大きい方が、造粒に要する時間
が短くて製造が容易であるのでよいとされていた程度で
ある。[0004] The granules used in the above-mentioned injection molding are generally made by granulating a mixture of inorganic powder for sintering and an organic binder to an appropriate size using an extrusion granulator or the like. Prepared by Conventionally, the size of this granulated material has not been taken into consideration, and the time required for granulation is determined by the size of the injection molding machine's insertion port (usually around 20 to 50 mm). This was considered acceptable because it was short and easy to manufacture.
【０００５】[0005]
【発明が解決しようとする課題】上記方法により焼結製
品を工業的な規模で製造する場合、各射出成形サイクル
毎の成形体の重量の安定性（成形サイクル毎の成形体で
重量のバラツキがないこと）が、脱バインダー及び焼結
を行なって最終的に得られる製品の寸法安定性に大きな
影響を及ぼすことが知られている。即ち、射出成形体の
重量は、成形体中に含まれる焼結用無機粉末の充填量に
ほとんど等しく、このため、各成形体毎で焼結用無機粉
末の充填量が異なると、最終的に得られる焼結体（最終
製品）の重量が変動し、その寸法も変動することになる
。[Problems to be Solved by the Invention] When producing sintered products on an industrial scale using the above method, it is important to check the stability of the weight of the molded product for each injection molding cycle (the variation in weight of the molded product for each molding cycle). It is known that the dimensional stability of the final product obtained by debinding and sintering is greatly influenced by In other words, the weight of the injection molded body is almost equal to the amount of inorganic powder for sintering contained in the molded body, and therefore, if the amount of inorganic powder for sintering is different for each molded body, the final weight will be The weight of the obtained sintered body (final product) will vary, and its dimensions will also vary.
【０００６】従来の射出成形法においては、大量生産を
行なった場合、射出成形体の重量変動を生じ、最終製品
である焼結体の寸法がばらつき、最終製品の寸法公差に
歩留りよく寸法を納めることが極めて困難であり、特に
精密機械部品、精密電子部品等の分野においては要求さ
れる寸法公差が非常に厳しいため、このような寸法のバ
ラツキは、製造上の大きな問題となっていた。[0006] In the conventional injection molding method, when mass production is carried out, the weight of the injection molded body fluctuates, and the dimensions of the sintered body, which is the final product, vary, making it difficult to meet the dimensional tolerances of the final product with a good yield. It is extremely difficult to do so, and the dimensional tolerances required are extremely strict, especially in the fields of precision mechanical parts and precision electronic parts, so such dimensional variations have been a major problem in manufacturing.
【０００７】従って本発明の目的は、寸法のバラツキな
く焼結体を製造することが可能な射出成形用造粒物を提
供することにある。[0007] Accordingly, an object of the present invention is to provide a granulated material for injection molding, which allows production of sintered bodies without dimensional variations.
【０００８】[0008]
【課題を解決するための手段】本発明によれば、焼結用
無機粉末と有機バインダーとの混合物から成る射出成形
用造粒物であって、射出成形機のシリンダー内径をｄ１
、射出成形機のスクリュー外径をｄ２ としたとき、
前記造粒物の最大寸法Ｄｍ は、下記式Ｄｍ ＜（ｄ１
−ｄ２ ）／２
を満足していることを特徴とする射出成形用造粒物が提
供される。[Means for Solving the Problems] According to the present invention, there is provided a granulate for injection molding made of a mixture of an inorganic powder for sintering and an organic binder, which has a cylinder inner diameter of d1 for an injection molding machine.
, when the outer diameter of the screw of the injection molding machine is d2,
The maximum dimension Dm of the granules is expressed by the following formula Dm < (d1
-d2)/2 is provided.
【０００９】[0009]
【作用】即ち、本発明は、射出成形用造粒物の最大寸法
Ｄｍ を、前記式を満足するように設定することにより
、上述した目的を達成することに成功したものである。
ここで前記式において、（ｄ１ −ｄ２ ）／２は、射
出成形機におけるシリンダー内壁とスクリュー先端部と
の間隔を意味する。即ち、前記式を満足しないような造
粒物を用いて射出成形を行なうと、造粒物が熔融する前
にほぼ固体の状態でシリンダーとスクリューに挟まれて
機械的な剪断力を受け、破砕されることになる。この際
、焼結用の無機粉末、例えば金属粉末は、機械的剪断力
によって有機バインダーと分離されるため、造粒物の均
一性が損なわれる。さらにシリンダー内で熔融加熱され
る過程で焼結用粉末と有機バインダーとの分離が進行し
、射出成形が困難となるばかりか、得られた射出成形体
中の焼結用粉末の分布が不均一となり、最終製品である
焼結体の寸法安定性が低下することになるのである。[Operation] That is, the present invention has succeeded in achieving the above-mentioned object by setting the maximum dimension Dm of the granules for injection molding so as to satisfy the above formula. In the above formula, (d1 - d2)/2 means the distance between the inner wall of the cylinder and the tip of the screw in the injection molding machine. In other words, when injection molding is performed using granules that do not satisfy the above formula, the granules are sandwiched between the cylinder and screw in an almost solid state and subjected to mechanical shearing force before being melted, causing them to fracture. will be done. At this time, the inorganic powder for sintering, for example, the metal powder, is separated from the organic binder by mechanical shearing force, which impairs the uniformity of the granules. Furthermore, during the process of melting and heating in the cylinder, separation of the sintering powder and the organic binder progresses, making injection molding difficult and causing uneven distribution of the sintering powder in the resulting injection molded product. As a result, the dimensional stability of the sintered body, which is the final product, decreases.
【００１０】本発明によれば、射出成形用造粒物の最大
寸法Ｄｍ が射出成形機におけるシリンダー内壁とスク
リュー先端部との間隔よりも小さく設定されているため
、造粒物が熔融する前のほぼ固体の状態において機械的
剪断力を受けることはなく、この結果として、得られる
射出成形体中の焼結用粉末の分布は均一であり、最終製
品である焼結体の寸法安定性も極めて良好なものとなる
。According to the present invention, since the maximum dimension Dm of the granules for injection molding is set smaller than the distance between the inner wall of the cylinder and the tip of the screw in the injection molding machine, the granules are It is not subjected to mechanical shearing force in an almost solid state, and as a result, the distribution of the sintering powder in the injection molded body obtained is uniform, and the dimensional stability of the final product, the sintered body, is also extremely high. It will be good.
【００１１】本発明において、用いる焼結用無機粉末は
特に制限されず、用途に応じて、各種金属、合金、金属
酸化物等の粉末を単独または２種以上の組み合わせで使
用することができる。In the present invention, the inorganic powder for sintering used is not particularly limited, and powders of various metals, alloys, metal oxides, etc. can be used singly or in combination of two or more, depending on the purpose.
【００１２】また有機バインダーとしては、通常、熱可
塑性の重合体が使用されるが、射出成形が可能である限
りにおいて、熱硬化性重合体を使用することも可能であ
る。一般に好適に使用されるものは、ポリエチレン等の
ポリオレフィン、アクリル系重合体、ポリビニルアルコ
ール、パラフィン系ワックス等であり、これらは単独ま
たは２種以上の組み合わせで使用される。これら有機バ
インダーは、一般に、上記焼結用無機粉末との合計量を
基準として、３０〜７０重量％の割合で使用される。[0012]Although thermoplastic polymers are usually used as the organic binder, thermosetting polymers can also be used as long as injection molding is possible. Generally, polyolefins such as polyethylene, acrylic polymers, polyvinyl alcohol, paraffin waxes, etc. are preferably used, and these are used alone or in combination of two or more. These organic binders are generally used in an amount of 30 to 70% by weight based on the total amount of the sintering inorganic powder.
【００１３】本発明の射出成形用造粒物は、最大寸法Ｄ
ｍ が前記式を満足するように調整される点を除けば従
来使用されている造粒物と同様の方法で調製され、例え
ば押出し造粒機等により焼結用無機粉末と有機バインダ
ーとの混合物をその最大寸法が前記式を満足するように
造粒することにより調製される。この射出成形用造粒物
は、次いでそれ自体公知の方法により、射出成形に付さ
れ、得られた射出成形品は、加熱等の手段により脱バイ
ンダーされ、さらに焼結に付され、最終製品とされる。The granules for injection molding of the present invention have a maximum dimension D
A mixture of an inorganic powder for sintering and an organic binder is prepared by the same method as a conventionally used granule except that m is adjusted to satisfy the above formula, for example, using an extrusion granulator or the like. It is prepared by granulating so that its maximum dimension satisfies the above formula. This injection molding granule is then subjected to injection molding by a method known per se, and the obtained injection molded product is debinding by heating or other means, and is further sintered to form the final product. be done.
【００１４】[0014]
【実施例】有機バインダーとして、低密度ポリエチレン
とパラフィン系ワックスとポリビニルアルコールとを重
量比で３：１：１の割合で使用した。この有機バインダ
ーと平均粒径５μｍ のカルボニル鉄粉とを、有機バイ
ンダーが全体の８重量％となる割合で混合、混練を行な
った。次いで、この混合物を用いて、押出し造粒機（挿
入口径；２０ｍｍφ）により、表１に示す種々のサイズ
の造粒物を調製した。EXAMPLE As an organic binder, low density polyethylene, paraffin wax and polyvinyl alcohol were used in a weight ratio of 3:1:1. This organic binder and carbonyl iron powder having an average particle size of 5 μm were mixed and kneaded in such a proportion that the organic binder accounted for 8% by weight of the total. Next, using this mixture, granules of various sizes shown in Table 1 were prepared using an extrusion granulator (insertion diameter: 20 mmφ).
【００１５】これら造粒物を用いて、表１に示すシリン
ダー内径及びスクリュー外径を有する射出成形機により
、ピッチ円直径 ２０ｍｍ 、厚さ ５ｍｍ、歯数１８
の歯車形状の成形体を成形し、成形体の重量測定を行な
った後に、脱バインダー、焼結を行ない（１３５０℃×
２時間）、得られた焼結体製品の寸法を測定した。（焼
結体の目標寸法は １９．９８〜２０．０２ ｍｍとし
た。）Using these granules, an injection molding machine having a cylinder inner diameter and a screw outer diameter shown in Table 1 was used to mold a pitch circle diameter of 20 mm, thickness of 5 mm, and number of teeth of 18.
After molding a gear-shaped molded body and measuring the weight of the molded body, the binder was removed and sintered (1350°C
2 hours), the dimensions of the obtained sintered product were measured. (The target size of the sintered body was 19.98 to 20.02 mm.)
【００１６】尚、成形体の重量及び焼結体の寸法
については、各々４０個の製品について測定を行ない、
平均値、標準偏差を求め、バラツキ具合の指標として標
準偏差／平均値を用いた。これらの結果を表１に示す。[0016] The weight of the molded body and the dimensions of the sintered body were measured for 40 products each.
The average value and standard deviation were determined, and the standard deviation/average value was used as an index of the degree of dispersion. These results are shown in Table 1.
【００１７】[0017]
【表１】[Table 1]
【００１８】[0018]
【発明の効果】本発明によれば、射出成形法により焼結
体を寸法のバラツキなく安定に量産することが可能とな
り、特に厳格な寸法公差が要求される精密機械部品、精
密電子部品等の用途に使用される焼結体の製造に極めて
有用である。[Effects of the Invention] According to the present invention, it is possible to stably mass-produce sintered bodies without dimensional variations using the injection molding method, and it is possible to produce precision mechanical parts, precision electronic parts, etc. that require especially strict dimensional tolerances. It is extremely useful for manufacturing sintered bodies used for various purposes.
Claims (2)
混合物から成る射出成形用造粒物であって、射出成形機
のシリンダー内径をｄ１ 、射出成形機のスクリュー外
径をｄ２ としたとき、前記造粒物の最大寸法Ｄｍ は
、下記式Ｄｍ ＜（ｄ１ −ｄ２ ）／２ を満足していることを特徴とする射出成形用造粒物。1. A granulated material for injection molding consisting of a mixture of an inorganic powder for sintering and an organic binder, wherein the inner diameter of the cylinder of the injection molding machine is d1, and the outer diameter of the screw of the injection molding machine is d2. A granulated material for injection molding, characterized in that a maximum dimension Dm of the granulated material satisfies the following formula Dm<(d1-d2)/2.
成形を行ない、脱バインダーを行なった後に焼結を行な
う焼結成形体の製造方法。2. A method for producing a sintered compact, which comprises injection molding the granulated material according to claim 1, removing the binder, and then sintering the product.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13848191A JPH04337003A (en) | 1991-05-14 | 1991-05-14 | Pellet for injection molding |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13848191A JPH04337003A (en) | 1991-05-14 | 1991-05-14 | Pellet for injection molding |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH04337003A true JPH04337003A (en) | 1992-11-25 |
Family
ID=15223088
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13848191A Pending JPH04337003A (en) | 1991-05-14 | 1991-05-14 | Pellet for injection molding |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH04337003A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2011190475A (en) * | 2010-03-11 | 2011-09-29 | Seiko Epson Corp | Granulated powder and method for producing granulated powder |
-
1991
- 1991-05-14 JP JP13848191A patent/JPH04337003A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2011190475A (en) * | 2010-03-11 | 2011-09-29 | Seiko Epson Corp | Granulated powder and method for producing granulated powder |
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