JP3410595B2 - Iron-based sintered oil-impregnated bearing and its manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an iron-based sintered oil-impregnated bearing and a method of manufacturing the same, and particularly from a home cleaning motor, a brush cutter for weeds, an electric tool motor, etc., from 10,000 revolutions per minute. The present invention relates to a ferrous sintered oil-impregnated bearing which is suitable for supporting a high-speed rotating shaft that rotates at a high speed of about 30,000 revolutions, can be manufactured at low cost, and has excellent durability, and a manufacturing method thereof.

[0002]

2. Description of the Related Art A ball bearing having a high durability is used as a bearing used in a motor of a cleaner or a brush cutter for weeds, which rotates at a speed of 10,000 revolutions per minute or more.

On the other hand, sintered oil-impregnated bearings are used in various industrial machines, motors, audio equipment, etc., and there are iron-based alloys and copper-based alloys of various compositions according to their respective functions.
There is no sintered bearing that can withstand the above high-speed rotation and can be manufactured at low cost.

[0004]

When a conventional sintered oil-impregnated bearing material is used under high-speed rotation conditions, seizure may occur,
Worn the shaft.

For example, in a copper-tin sintered alloy, a copper-zinc sintered alloy, etc., the material strength is low, so that cohesive wear occurs,
The porosity of the sliding part with the shaft is crushed and the supply of lubricating oil deteriorates,
The bearing performance may be deteriorated and may cause seizure. Also,
Materials such as copper, tin, and zinc are relatively expensive, and they also have the drawback of increasing the cost of the product.

In the case of iron-based materials such as iron-copper-based sintered alloys and iron-copper-zinc-based sintered alloys, liquid-phase-sintered ones are
There are drawbacks that the material is relatively hard, the shaft is worn, the coefficient of friction is high, and the bearing temperature is high. In addition, the material subjected to solid phase sintering had a low material strength and was apt to cause baking.

The present invention has been made in view of the conventional problems as described above, and an object thereof is to support a high-speed rotating shaft, which can be manufactured at low cost and has durability. An object is to provide an excellent iron-based sintered oil-impregnated bearing and a method for manufacturing the same.

[0008]

In order to achieve the above object, an iron-based sintered oil-impregnated bearing according to the present invention is made of a sintered alloy having oil contained in its pores, and the overall composition of the alloy is C: 0. Two
5 to 0.55% by weight, Cu: 3 to 10.8% by weight, N
i: 0.5 to 4.8% by weight, the balance being Fe and unavoidable impurities, and 5 to 12% by weight of Cu-Ni alloy phase particles dispersed between iron particles composed of iron ferrite phase and pearlite phase. It has a metallic structure, and is characterized in that the Ni content in the Cu—Ni alloy phase is 10 to 40% by weight.

Further, the method for manufacturing an iron-based sintered oil-impregnated bearing according to the present invention is Cu-Ni having a Ni content of 10 to 40% by weight.
5 to 12% by weight of alloy powder, graphite powder in an amount necessary for the amount of combined carbon with Fe after sintering to be 0.25 to 0.55% by weight, and reduced iron powder are the balance forming lubricant. the dust of the mixed powder, including
It is characterized in that the body is sintered at a temperature of 1100 ° C or higher and lower than the melting point of the Cu-Ni alloy powder.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an iron-based sintered oil-impregnated bearing and a method for manufacturing the same according to the present invention will be described below.

This sintered oil-impregnated bearing is composed of a relatively soft copper-nickel alloy phase, an intermediate hardness iron ferrite phase, and a relatively hard iron pearlite phase. The hardness of each phase is about 80 HV for copper-nickel phase, about 100 HV for ferrite phase, and about 180 HV for pearlite phase.
Before and after, and these quantities are as shown below,
When the amount is a specific amount, the conformability and abrasion resistance are improved, and the sizing processability is also improved. It is also low cost.

Under high-speed sliding conditions, the load on the bearing is large and the bearing is struck by the vibrations associated with the rotation of the shaft. Therefore, it is necessary to have higher wear resistance than ordinary bearings.

Therefore, the amounts of the ferrite phase and the pearlite phase of iron are approximately 7: 3 to 2: 8 in terms of the area ratio of the sectional structure.
Therefore, if the ferrite phase is too much or the pearlite phase is too much, the wear becomes large. This area amount corresponds to 0.26 to 0.63% by weight in the iron-carbon system, and corresponds to 0.25 to 0.55% by weight in the whole composition including the Cu-Ni alloy phase. To do.

The Cu-Ni alloy phase is a soft phase,
When it is 12% by weight, the familiarity and durability as a bearing for high speed rotation are improved. If the amount of Cu-Ni alloy phase is too large, the radial crushing strength becomes low, and plastic flow easily occurs during operation,
On the contrary, the durability of the bearing may be reduced.

The Cu--Ni alloy does not form a liquid phase when the sintering temperature is set to at least 1100 ° C. or higher in order to promote the sintering of the iron-carbon-based portion to enhance the material strength and reduce the pores. It becomes such a Cu-Ni composition. Therefore, the Ni content of the copper-nickel alloy is 10% by weight (melting point 11
50 ° C.) or higher is preferable. However, Ni is 40% by weight
If it exceeds (melting point 1260 ° C.), the melting point of the Cu—Ni alloy is high and powder production becomes difficult, which is not preferable.

The Cu-Ni alloy phase is preferably a relatively fine powder having a particle size finer than 100 μm and 44 μm or less of about 60 to 70% by weight.

As the iron, a reduced iron powder which is porous is used and is sintered at a relatively high temperature. As a result, a sintered alloy having fine pores can be obtained, and the oil retaining property can be improved. Further, by appropriately sealing the bearing sliding surface by ordinary sizing, oiling property and oil film formation on the sliding surface suitable for high speed rotation can be obtained.

The density of the sintered bearing is usually 5.8 to 6.4.
and g / cm ³ before and after the effective porosity of the time 18-2
6%, radial crushing strength is 400-640 MPa, air permeability is 15
The bearing is about 60 × 10 ⁻³ μm ² .

[0019]

EXAMPLES The embodiments of the present invention will be described more specifically below with reference to Examples and Comparative Examples.

As the raw material powder, the particle size is -150, respectively.
Reduced iron powder of mesh, copper alloy powder of Ni 30% by weight,
Copper powder and normal graphite powder were prepared and mixed in the composition shown in Table 1.

[0021]

[Table 1]

The amount of graphite added to each mixed powder is such that after sintering, the amount of carbon with respect to Fe is 0.6% by weight, and that of zinc stearate is 0.5% by weight. There is.

Each mixed powder was compacted into a cylindrical shape, sintered in a carburizing gas atmosphere at the temperature shown in Table 1, and then sized to obtain a sample.

Table 2 shows the air permeability, surface hardness and radial crushing strength when the effective porosity of the sample was 20% and 27%.

[0025]

[Table 2]

The comparison between Examples 1 and 2 and Comparative Examples 1 to 3 in which the added amount of Cu-Ni alloy powder is different shows that when the amount of Cu-Ni alloy powder is large, the air permeability tends to be high and the surface hardness is high. The radial crushing strength of Example 2 was maximized. As the bearing for high speed rotation, it is preferable that the air permeability is low, and the surface hardness and the radial crushing strength are high, so that the second embodiment can be said to be the best in characteristics.

Looking at Comparative Examples 4 and 5 using copper powder, in Comparative Example 4, since Cu was in a liquid phase during sintering, surface hardness, radial crushing strength and air permeability were all high. There is. In Comparative Example 5, the air permeability is low and the radial crushing strength is also low.

Next, Example 2 in which the Cu-Ni alloy phase was 10.4%, Comparative Example 2 in which the Cu-Ni alloy phase was 30.2%, and C
Each bearing sample was prepared by the same procedure as in Comparative Example 5 in which the u phase was 8% and the effective porosity was 24%, impregnated with an olefin-based lubricating oil, and a continuous running bearing durability test was performed. The rotating shaft used in the test is a quenched product made of S45C material, having an outer diameter of 10 mm and a rotation speed of 19,000 rotations per minute (sliding speed 597 m / min.). The PV value is 340
MPa · m / min. And

Comparing the time until seizure occurs on the bearing, it is about 10 minutes in Comparative Example 5 and about 15 in Comparative Example 2.
Baking occurred in time, but in Example 2, baking did not occur even after 100 hours of operation.

[0030]

As described above, according to the present invention, it is possible to provide a sintered oil-impregnated bearing having good durability as a bearing under high-speed rotation conditions at low cost, and to provide a cleaning motor, a brush cutter, etc. As a bearing of a device that rotates at high speed, the present invention can be applied in place of a ball bearing, and has an effect of expanding the use of sintered parts.

Continuation of the front page (56) Reference JP-A-61-104052 (JP, A) JP-A-4-124248 (JP, A) JP-A-57-108201 (JP, A) JP-A-59-38354 (JP , A) JP-A 5-117819 (JP, A) JP-A 1-225749 (JP, A) JP-A 51-14108 (JP, A) JP-A 5-86404 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C22C 38/00 304 C22C 33/02 C22C 38/08 F16C 33/10 F16C 33/14

Claims (2)

(57) [Claims] 1. A sintered alloy containing oil contained in pores,
The total composition of the alloy is C: 0.25 to 0.55% by weight, C
u: 3 to 10.8% by weight, Ni: 0.5 to 4.8% by weight, the balance being Fe and unavoidable impurities, and Cu- between the iron particles composed of an iron ferrite phase and a pearlite phase.
It has a metallic structure in which Ni alloy phase particles are dispersed in an amount of 5 to 12% by weight, and the Ni content in the Cu-Ni alloy phase is 10 to 4
An iron-based sintered oil-impregnated bearing characterized by being 0% by weight. 2. Cu-N having a Ni content of 10 to 40% by weight.
i alloy powder 5 to 12% by weight, graphite carbon in an amount necessary for the amount of combined carbon with Fe after sintering to be 0.25 to 0.55% by weight, and reduced iron powder in the balance for forming lubrication Pressure of mixed powder containing agent
A method for producing an iron-based sintered oil-impregnated bearing , which comprises sintering the powder at a temperature of 1100 ° C. or higher and lower than the melting point of the Cu—Ni alloy powder.