JPH045745B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a sintered alloy bearing and a method for manufacturing the same.
The present invention provides effective corrosion resistance and other characteristics in iron-based sintered alloy bearings, provides an engineering-advantageous manufacturing method for such sintered alloy bearings, and provides such characteristics at low cost. The aim is to provide various types of bearings. Iron-based bearings are widely used as sintered alloy bearings that are low in cost and have excellent strength. In other words, although copper-based and bronze-based bearings are also in practical use as this type of sintered alloy bearing, the raw material cost of iron-based bearings is a fraction of that of bronze-based bearings, which are relatively inexpensive. In fact, iron-based materials have no choice but to be used especially for high-load sintered machine parts because of their excellent strength. However, such iron-based sintered alloys have the decisive disadvantage of being easily corroded, and for this reason, it is necessary to apply rust prevention treatments such as blackening treatment and steam treatment, and it is not always effective. No rust prevention results were obtained.
It also has the disadvantage that it is difficult to use in applications where rust prevention is required, such as bearings, where rust prevention treatment cannot be applied. The present invention was devised after repeated studies in view of the above-mentioned circumstances, and is inexpensive, has preferable corrosion resistance, has excellent mechanical strength, and has high lubricity. We succeeded in obtaining a sintered alloy that can be appropriately used as a bearing. That is, such a product according to the present invention has a wt%
(hereinafter simply referred to as %), Fe: 28-70%, Cu: 15
~60%, Ni: 3~15%, Zn: 3~20%,
We propose a sintered alloy made by powder metallurgy, in which the remainder consists of unavoidable impurities, and in some cases, Pb: 10% or less and graphite 3% for the above basic composition. Any one or two of the following and Sn: 5% or less can be contained therein. Also, the manufacturing method is Cu, Ni,
One base material is a ternary Zn alloy, and the other is iron powder, which is then compacted and sintered.In order to prevent dezincing during the sintering process, the compact is heat-resistant. The material is charged into a steel (including metal) container and sintered. To further explain the present invention as described above, the present invention has four elements as basic components: iron, copper, nickel, and zinc, and in concrete production, the above-mentioned Cu, Ni, and Zn powders are used. Although it is complicated to adjust and prepare each component separately, which tends to increase costs, it is possible to achieve sufficient simplicity and cost reduction by preparing an alloy powder containing Cu, Ni, and Zn together. obtain. That is,
The ternary alloy material of Cu, Ni, and Zn is called nickel silver or nickel silver, and is widely used for various decorative purposes such as furniture, tableware, musical instruments, other utensils, and coins. By pulverizing the alloy material used for appliances and the like in this manner, it is possible to easily adjust the ternary alloy powder by simply adding and blending the ternary alloy powder to the iron powder. However, it is said that when this ternary alloy has a high Zn content, it becomes an (α+β) structure, resulting in low viscosity and poor workability, but in the powder metallurgy method of the present invention, this structure is If the amount of evaporation is suppressed, there will be no problem; on the other hand, the coating effect of zinc will prevent rust.
The anticorrosion effect is significantly exhibited, and the corrosion resistance of iron-based sintered alloys can be sufficiently improved. By the way, the present inventors have conducted an experimental study on the upper and lower limits of the Fe content in the case of making a four-element sintered alloy from the three-element alloy as described above.
I learned that it is 28-70%. In other words, when iron powder is mixed in an amount of 70% or more, the corrosion resistance rapidly decreases, and even if a three-element alloy powder is blended, a desirable oxidation resistance cannot be ensured, and furthermore, sliding properties and other properties deteriorate. Furthermore, if the iron powder content is less than 28%, the required amount of ternary alloy powder becomes large, and the object of the present invention, which is to obtain a low cost similar to that of iron-based sintered alloys, cannot be achieved. Cu is 15 to 60%, and if the Cu content is less than 15%, proper compatibility with the rotating shaft as a bearing cannot be obtained, and rust prevention properties are also deteriorated. Furthermore, if the Cu content exceeds 60%, the mechanical strength of the bearing body will be insufficient, making it particularly difficult to use it for high-load bearing purposes. Ni is 3 to 15%; if it is less than 3%, the oxidation prevention effect is insufficient due to the formation of a passive oxide film, while if it exceeds 15%, the oxidation prevention effect is saturated and it becomes expensive. Become. The Zn content is 3 to 20%, and if it does not reach 3%, the antirust and anticorrosion effects of Zn cannot be effectively obtained. On the other hand, if the Zn content exceeds 20%, it becomes difficult to prevent evaporation during sintering, and conformability and workability deteriorate, so this is the upper limit. Further added to the above composition
Pb content is 10% or less, and if it exceeds 10%, mechanical strength decreases. Similarly, if the graphite content is less than 3% and more than 3%, the strength of the product will decrease and the high strength of the iron powder-based bearing material will be impaired. Also, as mentioned above, the upper limit for Sn used in combination with Pb is 5%; even if it is added in excess of 5%, the effect will be saturated and the cost will increase, so this upper limit should be set. shall be. Regarding the sintering temperature in the manufacturing method of the present invention, Fe70% (ternary alloy 30%) and Fe28-30%
(ternary alloy 70-72%) and Fe50% (ternary alloy
(50%) can be carried out under the same conditions of 900 °C as in the case. In other words, originally it would be necessary to gradually raise the temperature from 900℃ as the iron content exceeds 50%, and conversely, it would be necessary to gradually lower the temperature from 900℃ when the iron content becomes less than 50%. It can be sintered even at the same temperature as in the case of 50%. However, by adjusting this sintering temperature to a high value, it is possible to improve the pressure resistance especially when the content of iron powder is high;
%, the temperature should be lower, and the optimum temperature in this case is experimentally 850-860°C. The use of an appropriate container to prevent the loss of Zn contained in nickel silver during sintering is particularly important when the content of nickel silver is high. Zn is coated with high efficiency to increase strength, and Zn coats the particle surface, contributing to improved corrosion resistance. Nickel has unique acid resistance and forms a passive oxide film against external corrosion, which acts to prevent corrosion from progressing. By forming a solid solution in the alloy to form an alloy, the antioxidant effect can be significantly increased, and therefore it is necessary to contain 3% or more as a sintered alloy. In the present invention, for the basic component system, Pb and Sn,
The appropriate addition of graphite is as described above. That is, by adding Pb and graphite, the coefficient of friction as a bearing is reduced and the lubricity is improved. However, when such Pb is added, the addition of tin contributes to improving the strength of the entire alloy and suppresses the lead sweat reaction of lead. In other words, the addition of tin in such cases is economically disadvantageous, but it is almost indispensable to obtain a nickel silver alloy powder containing lead, and the lead in this nickel silver improves the sliding properties of bearings, etc. At the same time, it also improves corrosion resistance and improves machinability, etc. When such properties are required, the addition of appropriate amounts of Sn and Pb is extremely significant. Furthermore, the addition of graphite according to the present invention has the effect of suppressing the temperature rise of the bearing as well as the above-mentioned lubricity, especially when used as an oil-impregnated bearing. However, the graphite powder used is usually 325 mesh under.
The volume ratio is 4 at the same weight for the applied metal powder.
Since the amount is ~5 times as large, a sufficient lubricating effect can be obtained with a content of 3% or less, and wear resistance is also high, especially in high-load applications. However, since the addition of graphite lowers the pressure resistance, it is preferable to add it to a product with a high proportion of nickel silver. Specific embodiments of the present invention will be described below. Sintered bearings having an inner diameter of 8 mm, an outer diameter of 12 mm, and a length of 12 mm were manufactured using raw material powders according to the composition of the present invention as shown in Table 1 below.

[Table] Apart from these, raw material powder made only of iron powder,
A powder-molded sintered bearing with the same dimensions as above was manufactured using bronze-based raw material powder containing 90% Cu and 10% Sn. The porosity of the sintered bearings is 20% according to the bearing standard, and the sintering temperature is 900℃.
The temperature was set at a constant temperature. During sintering, as the sintering temperature rises, in the case of the method according to the present invention, some of the zinc content evaporates and evaporates, and while evaporating, some of the zinc content permeates and welds to the surface of adjacent iron particles, reducing the amount of evaporation. The compacted powder compact was housed in a container provided with small holes. This method significantly reduces the diffusion of nickel silver when the content exceeds 50%, and when the content of nickel silver is 30% or less, sintering is performed in an open state. There is no substantial difference between the two. In addition, in ~ with 0.5 to 2.5% graphite added, the graphite is a fine powder of 325 mesh or less,
The amount of iron powder blended is reduced by an amount corresponding to this amount of graphite. In addition, in those containing lead or lead and tin, the amount of nickel silver or nickel silver and iron powder is reduced by an amount commensurate with the amount of lead alone or lead and tin added. For each sintered alloy obtained as above, its pressure resistance, temperature rise under test conditions of 3000 rpm with a total load of 10 kg, and rusting time determined by immersing it in 5% saline solution and leaving it for rusting. The results of each test are summarized in Table 2 below.

[Table] In other words, in terms of pressure resistance, the products of the present invention have achieved strength equivalent to that of conventional iron-based sintered alloy materials by increasing the content of nickel silver, and in terms of temperature rise values, they have achieved a strength comparable to that of conventional iron-based sintered alloy materials. In particular, those containing graphite have even achieved better values than bronze-based ones. The rusting test results were better than any of the comparative materials, and in particular, it was confirmed that it had excellent corrosion resistance that was ten times or more than tens of times higher than that of the iron-based comparative materials. Although this corrosion resistance is generally inversely proportional to the amount of iron powder, the Zn content also has a large effect, and these materials show the highest corrosion resistance even though the amount of iron powder is high. It is recognized that this is because the iron powder was sufficiently covered with Zn. According to the present invention as explained above, it is possible to exhibit excellent corrosion resistance while ensuring the desired strength in iron-based sintered alloys, and furthermore, it can be used as a bearing etc. by maintaining good lubricity etc. This invention has effects such as being able to reduce temperature rise when adopted, and is an invention that has great industrial effects.

Claims (1)

[Claims] 1 Fe: 28 to 70 wt%, Cu: 15 to 60 wt%, Ni:
A sintered alloy bearing produced by a powder metallurgy method, characterized in that it contains Zn: 3 to 15 wt%, Zn: 3 to 20 wt%, and the remainder consists of unavoidable impurities. 2 Fe: 28-70wt%, Cu: 15-60wt%, Ni:
Contains 3 to 15 wt%, Zn: 3 to 20 wt%, and one or two of Pb: 10 wt% or less, graphite: 3 wt% or less, and Sn: 5 wt% or less, with the balance A sintered alloy bearing characterized in that the sintered alloy bearing consists of unavoidable impurities. 3 Fe: 28 to 70 wt%, iron powder and powder using a base material of a ternary alloy of copper, nickel, and zinc.
Cu: 15~60wt%, Ni: 3~15wt%, Zn: 3~
A method for producing a sintered alloy, which is characterized by mixing to a concentration of 20wt%, compacting, and sintering.