【発明の詳細な説明】[Detailed description of the invention]
この発明は、相対的に気密化され外側層と、保
油容量の高い軸当接の内側層の２層構造もをつた
Fe系焼結材料製含油軸受に関するものである。
一般に、例えば扇風機などの家庭電化製品や、
自動車機器などにはFe系焼結材料製含油軸受が
多量に使用されていることはよく知られるところ
である。
この含油軸受は、Fe系焼結材料中に形成され
ている外部に連通した空孔（以下オープンポアと
いう）に油を含浸し、自己給油状態のまま無給油
で使用されるものであるが、含浸された油が運転
中にオープンポアを通して流出し易く、この結果
軸と軸受との当接面における油圧が低下して、油
の軸を支える力が小さくなることから、軸と軸受
間にかじりや焼付きなどの原因となる局部的接触
が起るようになり、比較的短時間で使用寿命に至
るものであつた。
そこで、本発明者等は、上述のような観点か
ら、運転中における含浸軸の流出を抑制したFe
系焼結材料製含油軸受を得べく研究を行なつた結
果、少なくともCu：５〜35重量％を配合した配
合組成を有する内側層形成用Fe系圧粉体部分
と、前記内側層形成用Fe系圧粉体部分に比して
相対的にCu配合量が低く、望ましくは10重量％
以下の割合で配合するか、あるいはCuを全く配
合しない配合組成を有する外側層形成用Fe系圧
粉体部分とからなる２層圧粉体を、焼結すると、
焼結時に前記内側層形成用Fe系圧粉体部分にお
けるCuまたは合金が前記外側層形成用Fe系圧粉
体部分中に毛細管現象により溶浸することから、
溶浸したCuまたはCu合金によつてオープンポア
が減少して気密化した外側層と、前記外側層への
CuまたはCu合金の溶浸移動により多孔化した軸
当接の内側層とからなるFe系焼結材料製２層軸
受素材が得られ、この場合、前記外側層および内
側層形成用Fe系圧粉体部分のいずれか、または
両方に、ＰおよびSnのうちの１種または２種を
0.01〜4.0重量％の割合で配合しておくと、焼結
時における溶融したCuまたはCu合金の流動性が
一段と向上するようになつて、溶融CuまたはCu
合金の外側層への含浸移動が一層促進されるよう
になり、さらに上記外側層形成用Fe系圧粉体部
分を構成する原料粉末の粒度を上記内側層形成用
圧粉体部分を構成する原料粉末の粒度より細かく
すると、同様に外側層への溶融CuまたはCu合金
の溶浸が活発となつて気密化が一段と向上するよ
うになり、このようにして製造されたFe系焼結
材料製２層軸受素材に油含浸を行なうと、この結
果のFe系焼結材料製２層含油軸受は、前記の気
密化した外側層によつて、相対的に多孔化して保
油容量の増加した内側層における含浸油の前記外
側層を通つての外部流出が著しく抑制されるよう
になるという知見を得たのである。
この発明は、上記知見にもとづいてなされたも
のであつて、空孔が内側層より溶浸したCuまた
はCu合金により充填されて相対的に気密化した
外側層と、前記外側層へのCuまたはCu合金の溶
浸移動により実質的に多孔化し、保油容量が増加
した軸当接の内側層とからなるFe系焼結材料製
２層含油軸受に特徴を有するものである。
なお、この発明の２層含油軸受を製造するに際
しては、内側層形成用Fe系圧粉体部分における
Cu配合量が５％未満では、Fe系焼結材料製２層
軸受素材におけるCuまたはCu合金溶浸による気
密化が不十分であるばかりでなく、同内側層にお
ける溶融CuまたはCu合金の外側層への溶浸移動
による多孔化も不十分で、所望の保油容量の増加
をはかることができず、一方35％を越えて多く配
合すると、焼結時の液相量が多くなりすぎて強度
の低下並びに変形をきたすようになることから、
その配合量を５〜35％とする必要があり、また外
側層形成用Fe系圧粉体にCuを配合する場合に
は、内側層形成用Fe系圧粉体部分におけるCu配
合量よりも相対的に低くすると共に、その配合割
合を10重量％以下にするのが望ましく、これは外
側層形成用Fe系圧粉体のCu配合量が10重量％を
越えると、内側層からの溶融CuまたはCu合金の
外側層への溶浸移動が相対的に少なくなつて、内
側層に十分な多孔化をもたらすことが困難になる
という理由によるものであり、さらにｐおよび
Sn成分には、内側層の溶融CuまたはCu合金の外
側層への溶浸を促進して、外側層の気密性を一段
と向上させ、この結果として内側層の多孔化を増
大させて保油容量を増加させる作用があるので、
必要に応じて配合するのがよく、この場合にはそ
の配合量が0.01％未満では前記作用に所望の効果
が得られず、一方4.0％を越えて配合すると、素
材の強度および靭性が劣化するようになることか
ら、その配合量を、0.01〜4.0％とするのが望ま
しい。
つぎに、この発明の２層含油軸受を実施例によ
り具体的に説明する。
実施例
原料粉末として、いずれも粒度―150meshの
Cu粉末、Ni粉末、Mo粉末、Sn粉末、Cu―Ｐ合
金（Ｐ：0.1％含有）粉末、Cu―Ｐ合金（Ｐ：10
％含有）粉末、Cu―Sn合金（Sn：0.1％含有）粉
末、およびCu―Sn合金（Sn：11％含有）粉末、
並びに粒度―100meshのFe粉末を用意し、これ
ら原料粉末を用いて、それぞれ第１表に示される
配合組成および層厚を有する外側層形成用Fe系
圧粉体部分と内側層形成用Fe系圧粉体部分とか
らなり、かつ外径：18mmφ×内径：８mmφ×長
さ：18mmの寸法をもつた２層圧粉体を4ton／cm2の
成形圧力にて成形し、ついでこれら２層圧粉体
を、アンモニア分解ガス雰囲気中、400〜600℃の
範囲内の所定温度で脱バインダした後、アンモニ
ア分解ガス雰囲気中、1000〜1150℃の範囲内の所
定温度に30分間保持の条件で焼結してFe系焼結
材料製２層軸受素材（以下２層焼結軸受素材とい
う）とし、引続いてサイジングおよび含油処理を
施すことによつて本発明Fe系焼結材料製２層含
油軸受（以下本発明２層焼結含油軸受という）１
〜12をそれぞれ製造した。
This invention also has a two-layer structure: an outer layer that is relatively airtight and an inner layer that abuts the shaft and has a high oil retention capacity.
This relates to an oil-impregnated bearing made of Fe-based sintered material. In general, home appliances such as electric fans,
It is well known that oil-impregnated bearings made of Fe-based sintered materials are widely used in automobile equipment and the like. This oil-impregnated bearing impregnates the pores (hereinafter referred to as open pores) that communicate with the outside formed in the Fe-based sintered material with oil, and is used without oil in a self-lubricated state. The impregnated oil tends to flow out through the open pores during operation, and as a result, the oil pressure at the contact surface between the shaft and bearing decreases, and the force supporting the oil shaft decreases, causing galling between the shaft and bearing. Localized contact that caused burn-in and the like began to occur, and the service life was reached in a relatively short period of time. Therefore, from the above-mentioned viewpoint, the present inventors developed a Fe
As a result of conducting research to obtain an oil-impregnated bearing made of a Fe-based sintered material, it was found that an Fe-based green compact portion for forming an inner layer having a composition containing at least 5 to 35% by weight of Cu, and an Fe-based compact for forming an inner layer. The content of Cu is relatively low compared to the green compact part, preferably 10% by weight.
When a two-layer green compact consisting of an outer layer-forming Fe-based green compact having a blending composition in the following proportions or no Cu at all is sintered,
During sintering, Cu or alloy in the Fe-based compact for forming the inner layer is infiltrated into the Fe-based compact for forming the outer layer by capillary action,
an airtight outer layer with reduced open pores due to infiltrated Cu or Cu alloy;
A two-layer bearing material made of Fe-based sintered material is obtained, consisting of an inner layer of shaft abutment made porous by infiltration and movement of Cu or Cu alloy, and in this case, Fe-based compacted powder for forming the outer layer and inner layer is obtained. One or two of P and Sn is added to either or both of the body parts.
When blended at a ratio of 0.01 to 4.0% by weight, the fluidity of molten Cu or Cu alloy during sintering is further improved, and the molten Cu or Cu
The impregnating movement of the alloy to the outer layer is further promoted, and the particle size of the raw material powder constituting the Fe-based green compact for forming the outer layer is reduced to the same level as the raw material forming the green compact for forming the inner layer. When the particle size is made finer than that of the powder, the infiltration of molten Cu or Cu alloy into the outer layer becomes active and airtightness is further improved. When the layer bearing material is impregnated with oil, the resulting two-layer oil-impregnated bearing made of Fe-based sintered material has an inner layer that is relatively porous and has an increased oil storage capacity due to the airtight outer layer. It has been found that the outflow of the impregnating oil through the outer layer is significantly suppressed. The present invention has been made based on the above findings, and includes an outer layer in which pores are filled with Cu or Cu alloy infiltrated from the inner layer to make it relatively airtight, and an outer layer in which Cu or Cu alloy is infiltrated into the outer layer. This is a two-layer oil-impregnated bearing made of Fe-based sintered material, which is made of a shaft abutting inner layer that has become substantially porous due to infiltration and movement of Cu alloy, and has an increased oil retention capacity. In addition, when manufacturing the two-layer oil-impregnated bearing of this invention, in the Fe-based green compact part for forming the inner layer,
If the Cu content is less than 5%, not only will the two-layer bearing material made of Fe-based sintered material be insufficiently airtight due to Cu or Cu alloy infiltration, but also the outer layer of molten Cu or Cu alloy in the same inner layer will be insufficient. The porosity caused by infiltration and migration is also insufficient, making it impossible to achieve the desired increase in oil retention capacity.On the other hand, if the amount exceeds 35%, the amount of liquid phase during sintering becomes too large, resulting in poor strength. This causes deterioration and deformation of the
The blending amount needs to be 5 to 35%, and when Cu is blended into the Fe-based green compact for forming the outer layer, the amount of Cu blended in the Fe-based green compact for forming the inner layer is relatively higher than that of the Fe-based green compact for forming the inner layer. In addition, it is desirable to keep the compounding ratio to 10% by weight or less. This is because if the Cu content of the Fe-based green compact for forming the outer layer exceeds 10% by weight, molten Cu from the inner layer or This is because the infiltration movement of the Cu alloy into the outer layer is relatively small, making it difficult to create sufficient porosity in the inner layer.
The Sn component promotes the infiltration of molten Cu or Cu alloy from the inner layer into the outer layer, further improving the airtightness of the outer layer, thereby increasing the porosity of the inner layer and increasing its oil storage capacity. Because it has the effect of increasing
It is best to add it as needed; in this case, if the amount added is less than 0.01%, the desired effect will not be obtained, while if it is added more than 4.0%, the strength and toughness of the material will deteriorate. Therefore, it is desirable that the blending amount is 0.01 to 4.0%. Next, the two-layer oil-impregnated bearing of the present invention will be specifically explained using examples. Example As raw material powder, particle size -150mesh was used in all cases.
Cu powder, Ni powder, Mo powder, Sn powder, Cu-P alloy (P: 0.1% content) powder, Cu-P alloy (P: 10
% content) powder, Cu-Sn alloy (Sn: 0.1% content) powder, and Cu-Sn alloy (Sn: 11% content) powder,
In addition, prepare Fe powder with a particle size of 100 mesh, and use these raw powders to form an Fe-based compact for forming an outer layer and an Fe-based compact for forming an inner layer, each having the composition and layer thickness shown in Table 1. A two-layer green compact consisting of a powder part and having dimensions of outer diameter: 18mmφ x inner diameter: 8mmφ x length: 18mm is molded at a molding pressure of 4ton/ cm2 , and then these two-layer green compacts are After debinding the body at a predetermined temperature within the range of 400 to 600°C in an ammonia decomposition gas atmosphere, the body is sintered under conditions of holding at a predetermined temperature within the range of 1000 to 1150°C for 30 minutes in an ammonia decomposition gas atmosphere. A two-layer bearing material made of Fe-based sintered material (hereinafter referred to as "two-layer sintered bearing material") is obtained by subsequently performing sizing and oil-impregnating treatment to obtain a two-layer oil-impregnated bearing material made of Fe-based sintered material (hereinafter referred to as "two-layer sintered bearing material"). (hereinafter referred to as the two-layer sintered oil-impregnated bearing of the present invention)1
~12 were produced respectively.
【表】
つぎに、この結果得られた本発明２層焼結含油
軸受１〜12について、以下の条件で摩耗試験を行
なつた。すなわち、前記軸受を水平配置の円筒状
ガイド内に嵌着固定した状態で、これに材質：
S45C、面粗さ：IS以下、軸受とのクリアラン
ス：25〜30μｍの軸を貫通装着し、前記ガイドを
介して前記軸受に15Kg／mm2の荷重を付加しなが
ら、前記軸を150m／minの速度で回転させ、60
分間経過後における前記軸受の軸当接面における
最大摩耗深さを測定した。この測定結果を第１表
に示した。
また、第１表には、比較の目的で、Ｃ：0.2
％、Ni：２％、Cu：２％、Fe：残りからなる配
合組成をもつた同寸法の１層圧粉体を、同一の条
件で焼結、サイジング、および含油処理すること
によつて製造した従来Fe系焼結材料製１層含油
軸受（以下従来１層焼結含油軸受という）の同一
条件での摩耗試験結果を示した。
さらに、第１表には、上記２層焼結軸受素材の
外周面から深さ：１mmの範囲（外側層）および内
周面から深さ：２mmの範囲（内側層）における
Cu含有量と密度比を合せて示した。
第１表に示される結果から、本発明２層焼結含
油軸受１〜12においては、いずれも外側層が内側
層より溶浸したCuまたはCu合金によつてオープ
ンポアが減少して気密化し、密度比が著しく向上
して運転中における含浸油の外部への流出が阻止
されたものになつており、一方内側層はCuまた
はCu合金の外側層への溶浸移動により多孔化し
て保油容量が増大したものになつていることか
ら、すぐれた耐摩耗性を示し、かつ著しく長期に
亘つての使用が可能であることを示しているのに
対して、従来１層焼結含油軸受は、オープンポア
を通しての含浸油の外部流出により比較的短時間
で焼付きを起し、使用寿命に至ることが明らかで
ある。
上述のように、この発明のFe系焼結材料製２
層含油軸受においては、内側層より溶浸したCu
またはCu合金によりオープンポアが減少して気
密化した外側層によつて運転中の含浸油の外部流
出が阻止され、かつ前記外側層へのCuまたはCu
合金の溶浸移動により多孔化して保油容量を増し
た軸当接の内側層によつて相対的に大きな保油容
量が確保されることから、著しく長期に亘つてす
ぐれた軸受性能を発揮するのである。[Table] Next, the resulting two-layer sintered oil-impregnated bearings 1 to 12 of the present invention were subjected to a wear test under the following conditions. That is, while the bearing is fitted and fixed in a horizontally arranged cylindrical guide, a material of:
S45C, surface roughness: IS or less, clearance with bearing: 25 to 30 μm. A shaft is inserted through the shaft, and while applying a load of 15 kg/mm 2 to the bearing via the guide, the shaft is moved at a speed of 150 m/min. Rotate at speed 60
The maximum wear depth on the shaft abutting surface of the bearing after 3 minutes had elapsed was measured. The measurement results are shown in Table 1. Also, in Table 1, for the purpose of comparison, C: 0.2
%, Ni: 2%, Cu: 2%, and Fe: the remainder by sintering, sizing, and oil-impregnating a single-layer compact of the same dimensions under the same conditions. We have shown the wear test results of a conventional single-layer oil-impregnated bearing made of Fe-based sintered material (hereinafter referred to as conventional single-layer sintered oil-impregnated bearing) under the same conditions. Furthermore, Table 1 shows the range of depth: 1 mm from the outer peripheral surface (outer layer) and the range of depth: 2 mm from the inner peripheral surface (inner layer) of the two-layer sintered bearing material.
The Cu content and density ratio are also shown. From the results shown in Table 1, in the two-layer sintered oil-impregnated bearings 1 to 12 of the present invention, the outer layer is made airtight by reducing open pores due to Cu or Cu alloy infiltrated from the inner layer. The density ratio has been significantly improved, preventing the impregnated oil from leaking outside during operation, while the inner layer becomes porous due to the infiltration and migration of Cu or Cu alloy to the outer layer, increasing the oil storage capacity. However, conventional single-layer sintered oil-impregnated bearings have It is clear that the outflow of the impregnated oil through the open pores causes seizure in a relatively short period of time, leading to the end of the service life. As mentioned above, the Fe-based sintered material 2 of this invention
In layer oil-impregnated bearings, Cu infiltrated from the inner layer
Or, the open pores are reduced by the Cu alloy, and the airtight outer layer prevents the impregnated oil from leaking out during operation, and the Cu or Cu
The inner layer of the shaft abutment, which has become porous due to the infiltration movement of the alloy and increases its oil storage capacity, ensures a relatively large oil storage capacity, which provides excellent bearing performance over an extremely long period of time. It is.