KR100961459B1 - Sintered oil-containing bearing and its manufacturing method - Google Patents

Abstract

Provided are a sintered bearing and a method for manufacturing the same, which can suppress wear of a shaft while suppressing wear of the bearing itself even under high surface pressure conditions.

The base part excluding the pores is a sintered bearing having a metal structure composed of a copper alloy phase composed of at least one of Cu, Sn, Zn, Ni, and P, a ferrite phase, and an iron oxide phase dispersed in the ferrite phase. . More preferably, the copper alloy phase is composed of Cu: 10 to 59% by mass and at least one species of Sn, Zn, Ni, and P: 1 to 5% by mass, and the iron oxide phase has a cross sectional area ratio of the known portion excluding pores. 20% and the remainder of the ferrite phase is composed of Fe and unavoidable impurities.

Sintered, powder, bearing containing, pore, iron, copper

Description

Sintered bearing and its manufacturing method {SINTERED OIL-CONTAINING BEARING AND ITS MANUFACTURING METHOD}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sintered bearing bearing suitable for various motors, such as a fan motor of an indoor blower mounted on an automobile, a seat driving motor, and a spindle motor mounted on an information device or an acoustic device. And to a method for producing the same.

The pores are dispersed in metal bases such as pure iron, bronze, iron-carbon, iron-copper-carbon, and iron-bronze, and sintered bearings impregnated with lubricating oil can be lubricated for a long time without lubrication. It is used for various bearing applications with the advantage of being present and being easy to manufacture.

Under these circumstances, sintered bearings are often used in bearings for motors such as fan motors for indoor blowers mounted on automobiles, motors for seat driving, and spindle motors mounted in information devices and acoustic devices. In view of seizure resistance and aggressiveness, sintered bearings using metal bases of pure iron or iron-carbon and iron-copper-carbon are hardly used. On the other hand, sintered bearings having a bronze-based metal base are excellent in sticking resistance and shaft aggression, but are difficult in terms of wear resistance and cost. Therefore, as the bearings for motors described above, sintered-containing bearings (Patent Documents 1, 2, etc.) made of an iron-bronze-based metal base having both wear resistance of an iron-based metal base and sticking resistance of a bronze-based metal base are widely used. .

Patent Document 1: Japanese Patent Publication No. 2003-l20674

Patent Document 2: Japanese Patent Application Laid-Open No. 2005-082867

In recent years, with the miniaturization of the motor, the bearing accommodated in the motor also tends to be miniaturized, and as a result, the bearing pressure received by the bearing also tends to increase. For this reason, conventionally, the iron-bronze-based metal-based sintered bearing widely used for motors has a problem that it is easy to wear under high surface pressure conditions because the iron part is soft and soft. On the other hand, iron-copper-carbon-based metal-based sintered bearings in which the iron part is made of pearlite structure can be satisfied in terms of wear resistance, but there is a problem that the wear of the shaft increases because the entire metal base is hardened. Did not reach.

Under such circumstances, an object of the present invention is to provide a sintered bearing and a method of manufacturing the same, which can suppress wear of a shaft while suppressing wear of the bearing itself even under high surface pressure conditions.

In order to solve the above problems, the inventors have intensively studied, and as a result, if the iron base of the metal base is basically a ferrite structure and only a part of the iron part is a hard phase, the wear of the bearing itself is suppressed. It was found that the abrasion of the shaft can be suppressed. The sintered bearing of this invention was completed by such knowledge, and let it be a thing which disperse | distributed iron oxide as a hard phase in the ferrite phase.

Specifically, the sintered bearing of the present invention has a copper alloy phase composed of at least one of Cu, Sn, Zn, Ni, and P, with a known portion excluding pores, a ferrite phase, and an iron oxide phase dispersed in the ferrite phase. It is characterized by showing the metal structure which consists of.

Moreover, the manufacturing method of the sintering containing bearing of this invention is iron powder, single powder whose total composition becomes 10 to 59 mass% of Cu, and at least 1 sort (s) of 1 to 5 mass% of Sn, Zn, Ni, and P, A raw material powder preparation step of adding and mixing an alloy powder or a mixed powder thereof, a molding step of molding into a bearing shape having an inner circumferential surface slidingly supporting the rotating shaft using the obtained raw material powder, and a sintering step of sintering the obtained molded body; The manufacturing method of the sintering bearing which has the impregnation process which impregnates lubricating oil in the pore of the sintered sintered bearing WHEREIN: It is characterized by using the iron powder whose reduction weight becomes 0.35-2 mass% as said iron powder.

In the sintered-bearing bearing of the present invention, a metal structure composed of a copper alloy phase composed of at least one of Cu, Sn, Zn, Ni, and P, and a base portion excluding pores, a ferrite phase, and an iron oxide phase dispersed in the ferrite phase In this regard, the wear resistance of the shaft is suppressed while the wear of the shaft is suppressed.

Moreover, the manufacturing method of the sintering containing bearing of this invention provides the method of manufacturing such a sintering containing bearing by a simple method. The present invention exhibits an excellent effect that it can cope with an increase in bearing surface pressure due to the recent miniaturization of a motor, and is mounted on a fan motor, a seat driving motor, an information device or an acoustic device of an indoor blower mounted on an automobile. It is suitable for various motors such as spindle motors.

[Sintered Bearing]

An example of the metal structure of the sintered containing bearing which concerns on this invention is shown in FIG. The black part in the figure represents pores, and in this example, the black pores are composed of large pores in which gaps between the iron powders remain, and minute pores generated by using reduced iron powder as an iron powder as a raw material. The remaining part is known and consists of gray iron parts and white copper alloy phases.

The iron part mainly has a skeletal role for suppressing abrasion, and the copper alloy phase has a role of preventing sticking with the shaft and reducing friction. The iron part is basically composed of light gray ferrite tissue, and part of which is a dark gray iron oxide phase. The iron oxide phase dispersed in the ferrite phase has a higher hardness than the iron of ferrite. As the iron portion is constituted of a low-hardness ferrite phase and a high-hardness iron oxide phase, the low-hardness ferrite phase reduces the aggression to the shaft, and the high-hardness iron oxide phase exhibits the effect of suppressing wear.

In the sintered bearing of the present invention, when the amount of the iron portion is insufficient, the copper alloy phase becomes excessive, the overall hardness decreases, and the wear increases. On the contrary, when the iron portion is excessive, the copper alloy phase is insufficient and the wear of the shaft is increased. For this reason, it is preferable that the ratio of Cu to the total composition of the matrix part except a pore is 10-59 mass%. That is, when the amount of Cu is less than 10% by mass, sticking tends to occur, and when added in excess of 59% by mass, bearing wear tends to increase. Cu is alloyed with any one or more elements of Sn, Zn, Ni, and P to form the copper alloy phase. These elements strengthen the copper alloy phase and contribute to the improvement of wear resistance of the copper alloy phase. However, when the amount of these elements is excessive, wear of the shaft tends to increase. For this reason, it is preferable to make the ratio which any one or more elements of Sn, Zn, Ni, and P occupy for the whole composition of the known part except a pore exists in the range of 1-5 mass%.

In the sintered-bearing bearing of the present invention, a dark gray iron oxide phase is dispersed in an iron part mainly composed of a light gray ferrite phase, contributing to improvement of its wear resistance. If the amount of the iron oxide phase is insufficient, wear resistance decreases and wear increases. On the contrary, if the amount of the iron oxide phase is excessive, wear of the shaft increases. For this reason, it is preferable to make iron oxide phase into 3 to 20% of range in the cross-sectional area ratio of the base part except a pore.

In addition, as conventionally performed in a sintered bearing, dispersing at least one solid lubricant component among graphite, molybdenum disulfide, manganese sulfide, and calcium fluoride in pores is effective in preventing seizure and in reducing friction coefficient. Of these solid lubricant components, graphite in particular exhibits a high effect. When the solid lubricant component is dispersed in the pores, the solid lubricant component is dispersed in the part of the large pores in which the gap between the iron powders remains.

When the solid lubricant component is too small, the effect of addition is insufficient. On the contrary, when the solid lubricant component is excessively large, the sintering of the matrix is inhibited and the strength of the matrix is lowered. For this reason, when disperse | distributing at least 1 type of solid lubricant components of graphite, molybdenum disulfide, manganese sulfide, and calcium fluoride in a pore, it is preferable that the quantity shall be 0.2-2 mass parts with respect to 100 mass parts of said matrix components. .

[Method for Manufacturing Sintered Bearing]

In order to obtain the sintered-containing bearing having the above metal structure, the manufacturing method of the sintered-containing bearing of the present invention has the iron oxide phase dispersed in the iron portion from the state of the raw powder. In other words, the iron powder is partially oxidized.

Specifically, the iron powder is hydrogen-reduced iron powder, and a reduction weight of 0.35 to 2% by mass is used. The reduction weight loss is a percentage of mass reduction when the powder is heated in the hydrogen stream, and can be replaced with the amount of oxygen of iron oxide in the iron powder. The reduction loss is specifically measured by the reduction loss test of iron powder described in JIS H 2601. When the reduction loss of the iron powder is less than 0.35% by mass, the amount of the iron oxide phase is small and the desired wear resistance is not obtained. On the other hand, when it exceeds 2 mass%, the quantity of the iron oxide phase in a ferrite phase will increase, shaft wear will increase and the compressibility of a powder will fall remarkably.

The copper alloy phase contains Cu and these copper alloy phase reinforcing elements as a single powder so that the total composition of the raw material powder is Cu: 10 to 59 mass% and at least one of Sn, Zn, Ni, and P: 1 to 5 mass%. Solid powder), and may be formed by any of a method of alloying in the sintering process or a method of adding in a state of copper alloy powder in advance. Therefore, single powder, alloy powder or mixed powder of these elements can be used.

In addition, when thin copper powder is used as all or part of the Cu component of the raw material powder, the surface of the sintered bearing is covered with a copper layer, and the amount of exposed iron is reduced, thereby preventing adhesion to the shaft and the like. It is preferable because the effect of lowering the coefficient of friction is also obtained.

Raw material powder is obtained by the raw material powder preparation process which mixes said iron powder and said powder for copper alloy phase formation. The raw material powder thus obtained has a molding step of forming into a bearing shape having an inner circumferential surface slidingly supporting the rotating shaft, the sintering step of sintering the obtained molded body, and the pores of the sintered sintered bearing, similarly to the manufacturing method of the conventional sintered bearing. It is manufactured through the impregnation process of impregnating lubricating oil.

In the said process, you may add another process, such as a repressurization process after a sintering process or after an impregnation process similarly to the manufacturing method of the conventional sintering containing bearing. In addition, it is preferable to shape | mold so that the density ratio of a molded object may be about 70 to 85% at the said molding process, and it is preferable to make sintering temperature about 760-800 degreeC equivalent to the conventional bronze type sintered bearing.

Graphite powder, molybdenum disulfide powder, manganese sulfide powder, and calcium fluoride powder with respect to 100 parts by mass of the raw powder composed of the iron powder and the powder for copper alloy phase formation are obtained in order to obtain a sintered bearing in which the solid lubricant is dispersed in the pores. The desired sintered-containing bearing is prepared by adding 0.2-2 parts by mass of the powder of at least one solid lubricant component and mixing them as raw material powders, and subjecting the raw material powders to the above-described forming step, sintering step, and impregnation step. You can get it.

(Example)

The raw material powder shown in Table 1 was prepared, each raw material powder was added and mixed by the mixture ratio shown in Table 2. Each powder thus obtained was compacted into a cylindrical shape having an inner diameter of 10 mm, an outer diameter of 16 mm and a total length of 10 mm at a molding pressure of 300 MPa, and the green compact was sintered at 780 ° C. in an ammonia decomposition gas atmosphere. After sintering, repressurization was performed to obtain a bearing test sample. Metal structure observation was performed about the obtained bearing test sample, and the ratio of the iron oxide phase occupying the base part except a pore was investigated. The results are shown in Table 3.

Moreover, the bearing test sample was impregnated with synthetic lubricating oil which has a polyol ester as a main component, and the bearing test was done for 200 hours by the bearing tester. In the bearing test, the rotating shaft used was made of S45C material, and the operating conditions of the tester were the rotational speed of the shaft at 5000 rpm, the surface pressure of 3 MPa, and the environmental temperature at room temperature. After this bearing test, the wear amount of the bearing and the shaft was measured. The results are shown in Table 3 together.

According to Examples 01-03 and Comparative Examples 1 and 2 of Table 2 and Table 3, the influence of the reduction loss of iron powder can be investigated. In the case where iron reduction with a reduction loss exceeding 2% by mass (Comparative Example 01), the amount of iron oxide phase in the matrix exceeds 20 area%, the amount of shaft wear is large, and the amount of bearing wear is large. On the other hand, in the case where the reduction loss uses 0.35 to 2% by mass of iron (Examples 01 to 03), the amount of iron oxide in the matrix is 3 to 20 area%, the amount of shaft wear and the amount of bearing wear are suppressed, and the shaft aggression and the wear resistance of the bearing are reduced. Both are showing good values. However, in the case of using iron powder whose reduction loss is less than 0.35% by mass (Comparative Example 2), the amount of bearing wear is rapidly increasing.

From this, if the reduction loss is 0.35 to 2% by mass as iron powder, the proportion of the iron oxide phase occupying the base portion excluding the pores becomes 3 to 20% in the cross-sectional area ratio, and the bearing resistance and the shaft attack resistance are improved. It was confirmed that it worked.

According to Examples 2, 4-8 of Table 2 and Table 3, and Comparative Examples 4, 5, the influence of the amount of Cu which occupies for the whole composition can be investigated. When the amount of Cu (the sum of the electrolytic copper powder and the thin copper powder) is less than 10 mass% (Comparative Example 4), the amount of shaft wear increases, but the amount of Cu is 10 to 59 mass% (Examples 2 and 4 to 8). ), The wear amount of the shaft is suppressed, and the wear amount of the bearing is also suppressed to a low value, indicating good wear resistance and shaft attack resistance of the bearing. However, when the amount of Cu exceeds 59 mass% (Comparative Example 5), the amount of wear of the bearing and the amount of shaft wear increase on the contrary.

From this, it was confirmed that the amount of Cu in the total composition is effective in improving the wear resistance of the bearing and the reduction of the shaft aggressiveness in the range of 10 to 59 mass%.

By comparing Examples 2 and 6 of Table 2 and Table 3, the effect of using a thin copper powder can be investigated. In Examples 2 and 6, the amount of Cu in the total composition was the same at 32 mass%, and both the amount of bearing wear and the amount of shaft wear were low, showing good results. Example 2 using the thin copper powder did not use the thin copper powder. Compared with Example 6, both the bearing wear amount and the shaft wear amount were lowered, and the effect of improving the wear resistance and suppressing the shaft attack by the thin copper powder was confirmed.

According to Examples 2, 4-8, and Comparative Example 3 of Table 2 and Table 3, the influence of the amount of Sn in the overall composition can be investigated. When the amount of Sn is less than 1% by mass (Comparative Example 3), the strength of the copper alloy phase is insufficient, and the amount of bearing wear increases. On the other hand, when Sn amount is 1-5 mass% (Examples 2 and 4-8), the copper alloy layer is fully strengthened and the bearing wear amount is lowered. From this, it was confirmed that the wear resistance of the bearing improves in the range of 1-5 mass% of Sn in whole composition.

By Example 2, 9, 10, and Comparative Example 6 of Table 2 and Table 3, the influence of addition of a solid lubricant (graphite) can be investigated. In the example in which no solid lubricant is included (Example 2), in the example in which the solid lubricant powder was added to disperse the solid lubricant in the pores (Examples 9 and 10), it was found that the shaft wear was suppressed by the solid lubricant. have. However, in the example (comparative example 6) in which the addition amount of a solid lubricant exceeds 2 mass%, the bearing wear amount increases and the shaft wear amount also increases.

From this, although the amount of shaft wear was suppressed by the addition of 0.2-2 mass% of solid lubricant, it was confirmed that addition of the solid lubricant exceeding 2 mass% impairs the wear resistance of a bearing.

The sintered bearing of the present invention can suppress the abrasion of the shaft while suppressing the wear of the bearing itself even under high surface pressure conditions. It is to provide a method of manufacturing. Accordingly, the sintered bearing of the present invention and the manufacturing method thereof are miniaturized, and a fan motor, a seat driving motor, a spindle motor mounted on an information apparatus, an acoustic apparatus, or the like, which is miniaturized and mounted on an automobile which tends to increase in surface pressure. It is suitable for various motors.

1 is an example of a metal structure photograph of a sintered bearing of the present invention.

Claims (6)

In a sintered bearing containing a metal structure consisting of a copper alloy phase composed of Cu, at least one of Sn, Zn, Ni, and P, a ferrite phase, and an iron oxide phase dispersed in the ferrite phase, except for the pores, The copper alloy phase is composed of 10 to 59% by mass of Cu and at least one of Sn, Zn, Ni, and P: 1 to 5% by mass in a mass ratio occupying the total composition of the matrix portion excluding pores, The iron oxide phase is 3 to 20% by the ratio of the cross-sectional area of the base portion excluding pores, The remainder ferrite phase consists of Fe and inevitable impurities, Sintered bearing, characterized in that the porosity of the bearing is 15 to 30%. delete The sintered-containing bearing according to claim 2, wherein at least one solid lubricant component of graphite, molybdenum disulfide, manganese sulfide, and calcium fluoride is dispersed in the pores with respect to 100 parts by mass of the known component. A rotating shaft is slid using a raw material powder preparation step of adding and mixing a single powder, an alloy powder, or a mixed powder thereof consisting of Cu, Sn, Zn, Ni, and P to iron powder, and mixing the obtained raw powder. In the manufacturing method of the sintering containing bearing containing the shaping | molding process of shape | molding to the bearing shape which has an inner peripheral surface to support, the sintering process of sintering the obtained molded object, and the impregnation process of impregnating lubricating oil in the pore of the sintered sintered bearing, The addition amount of the single powder, the alloy powder, or a mixed powder thereof consisting of at least one of Cu and Sn, Zn, Ni, and P is 10 to 59% by mass of Cu and the raw material powder in the total composition of the raw material powder. In the total composition, at least one of Sn, Zn, Ni, and P is an amount of 1 to 5% by mass, An iron powder having a reduction loss of 0.35 to 2% by mass is used as the iron powder. The method for producing a sintered bearing according to claim 4, wherein thin copper powder is used as all or part of the Cu component of the raw material powder. The raw material powder according to claim 4 or 5, wherein 0.2 to 2 parts by mass of at least one solid lubricant powder of graphite, molybdenum disulfide, manganese sulfide, and calcium fluoride is added and mixed with respect to 100 parts by mass of the raw material powder. A method for producing a sintered bearing, characterized by using.

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