Stock material or miscellaneous articles – All metal or with adjacent metals – Having metal particles
Reexamination Certificate
1998-12-29
2001-03-06
Speer, Timothy M. (Department: 1775)
Stock material or miscellaneous articles
All metal or with adjacent metals
Having metal particles
C428S677000, C075S247000, C075S255000, C420S474000, C420S496000, C384S912000
Reexamination Certificate
active
06197432
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a sliding material with excellent abrasion resisting property, such as high abrasion hardness and, more particularly to a sliding material, in which the sliding material is suitable as material of a sliding member, such as the sliding bearing and washer used in vehicles, industrial machines and agricultural machines, in which the sliding material is excellent in the abrasion resisting property and in which the sliding material is effective for applications under a severe boundary lubricating condition without a circulation of an lubricating oil.
PRIOR ART TECHNIQUE
In general, among sliding materials, the sliding material, which is used as sliding bearing members, such as the sliding bearing, bush and washer, are made mainly with sintered alloy, which consists substantially of bronze alloy or lead bronze alloy. These alloys exhibit an excellent slidablity under a lubricating conditions utilizing the oil lubrication, in which the lubricating oil is circulated through a space between the sliding member and the rotating shaft supported thereby.
The lubricating condition becomes to be severe and then reaches a boundary lubricating condition. In the boundary lubricating condition, it is imposible to utilize the oil lubricantion. In addition to this, the boundary lubricating condition causes an occurence in excess of irregular abrasion with respect to the sliding material and the rotating shaft supported thereby.
Namely, a lead bronze alloy used as a sintered layer of the sliding material has therein lead content which is excellent in the lubricating property and affinity. Additionally, the lead particles are dispersed without segregation in all parts of the bronze base matrix of the sintered alloy. Thus, the bearing member or sliding member using as a raw material of sintered materials of bronze or lead bronze alloy exhibit a satisfactory lubricating property under lubricating conditions utilizing the oil lubrication. However, under severe boundary lubricating conditions without a circulation of the lubricating oil, the bearing member or sliding member by fabricated by the sintered bronze or lead bronze alloy do not exhibit a good abrasion resisting property. Additionally, it is reported that an excessive abrasion is caused at the time of using the bearing member of bronze or lead bronze alloy under the boundary lubricating condition.
To solve the above defects, Japanese Patent Publication No. 50844/1982 proposes bearing materials or sliding materials, which are used for making the bearing member or sliding member. The materials comprise base matrix of lead bronze alloy and dispersed particles of hard compounds, such as Fe, P powder, Mo and Co powder, and Ni—base alloy powder. The dispersed particles are precipitated in the base matrix. The proposed sliding materials have therein the improved seizure resisting property and abrasion resisting property.
Japanese Patent Publication No. 198440/1994 also proposes sliding materials or bearing materials, which are used for making the bearing member or sliding member. The proposed material are is imparted with a good seizure resisting property and an excellent abrasion resisting property, by adding graphite pharticles and Ni—B compound particles to the base matrix of lead bronze alloy.
However, the hard particles, which are precipitated as hard element or intermetallic compound in the base matrix of these bearing materials and sliding materials, are mainly those of intermetallic compound, such as Fe, P Ni—B and have a tendency to be crystallized. Although the precipitation of hard particles in the base matrix has an effect of enhancing the abrasion resisting property of lead bronze base matrix of the sliding material. These particles of hard element or intermetallic compound have thereon sharply pulverized surface shapes with knife edges. Consequently, it is not suitable to use as bearing materials or sliding materials for making bearing member or sliding member of engines and drive parts of vehicles or the like, because the sliding or bearing member with use of these bearing or sliding materials will cause an abrasion of the rotating shaft supported by sliding or bearing member, shaft, despite the fact that the abrasion of the bearing member or sliding member themselves can be reduced.
In general, the bearing materials or the sliding materials are subjected as starting materials to a mechanical working process, thereby resulted in the sliding bearing member with use of engine parts of vehicles or the like. The resultant sliding bearing member has thereon a sliding surface, which is subjected to a cutting process utilizing a machine cutter or grinder. However, during the course of cutting or grinding of the bearing material or sliding material, it is impossible that the bearing or sliding material will be subjected to a cutting or grinding process utilizing a cemmented carbide tool. This is because the bearing or sliding material has therein a precipitation with excessively high hardness.
Consequently, the cutting or grinding process of the sliding or bearing material with excessively high hardness does not permit the use of the cemmented carbide cutter and therefor necessiates the use of a diamond cutting tool with hardness higher than that of the cemmented carbide cutters.
Namely, as described above, the proposed bearing material or sliding material has therein a base matrix of bronze alloy or lead bronze alloy and hard particles added thereto and precipitated therein.
The additive, which is added as hard material particles to the base matrix of bronze or lead bronze alloy, is precipitated in the base matrix of bronze or lead bronze alloy, thereby enhancing the hardness of the base matrix. Additionally, the additive to be added has therein the intermetallic compound or hard metallic particle with Vickers hardness (Hv) of 1,000 or above.
Therefore, the resultant bearing material or sliding material is excessively hard. In addition, the additive, such as the hard material particles, have inferior property of sintering with lead bronze alloy constructing the base matrix of the bearing material. Therefore, during the sliding bearing member, such as the slide bearing or the like, supports a rotating shaft, hard material particles being added to and precipitated in the base matrix are detached as worn-out particles and cause a damage to the rotating shaft.
The property of sinterability of the hard material particles with respect to the base matrix lead bronze alloy is inferior and hence the hard material particles have another problems. When the condition of lubrication prevailing between the sliding bearing and the rotating shaft supported thereby reaches the boundary lubricating condition, the sliding bearing and the rotating shaft become to be in direct contact with each other. In such a direct contact, hard material particle precipitated in the base matrix intervene between the sliding surface of the slide bearing and the rotating shaft, and the load applied by the rotating shaft is supported only by the hard material particles, instead of the base matrix of the bronze alloy. Under this condition, frictional heat is generated between the supported shaft and the hard material particles precipitated in the base matrix of bronze alloy. But, it is difficult that the friction heat is dissipated to the outside.
In addition to this, the generation of friction heat is accelerated, so as to cause a temperature elevation to an excessive high degree, thereby resulting in seizure between the slide bearing and the rotating shaft supported thereby.
The present invention seeks to overcome the above drawbacks inherent in the prior art bearing materials and sliding materials, and it has an object of providing a bearing material or a sliding material with an excellent abrasion resisting property. The sliding material comprises a base matrix constituted by a copper base sintered alloy, such as lead bronze base sintered alloy, and hard material particles dispersed or precipitated without any segregation
Fujita Masahito
Saitou Yasushi
NDC Company Ltd.
Savage Jason
Speer Timothy M.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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