KR100932544B1 - Sintered bearing and its manufacturing method - Google Patents

Abstract

It is a technical problem of the present invention to provide a sintered bearing capable of improving strength, extreme pressure characteristics, and abrasion resistance, and ultimately increasing durability life. To this end, the sintered bearing of the present invention comprises a body, and the body is iron to the base portion responsible for the strength of the body, copper to enhance the rapid discharge and strength characteristics of the frictional heat, and the iron diffuses to harden the iron during heat treatment And carbon nanotube (CNT) particles dispersed and strengthened in the body to improve strength or lubrication and friction properties of the body, and furthermore, a contact surface with the counterpart member of the body. It provides a sintered bearing that can be smoothly lubricated during the initial operation by forming a plurality of oil grooves of the cross spiral shape to cross each other.

Iron-Copper-Carbon-CNT Type, Sintered, Bearing, Containing, Excavator, Joint, Oil Groove

Description

Sintered bearing and its manufacturing method {SINTERED BEARING AND MAUFACTURING METHOD THEREOF}

The present invention relates to a sintered bearing, and more particularly, to a sintered bearing and a method for manufacturing the same, which can improve strength, extreme pressure characteristics, and wear resistance, and ultimately increase durability.

In general, sintered bearings are bearings made by sintering iron-copper-carbon powders, which are used together with pins (or shafts) in a number of joint areas included in industrial and construction machinery, and pins (or shafts). It also serves to reduce frictional resistance with the pin (or shaft).

Such iron-copper-carbon sintered bearings usually have internal pores of about 20% by volume, and the internal pores contain oil. The contained oil is expanded inside the bearing by the frictional heat generated when the pin and the bearing are rubbed, and then discharged to the outside of the bearing. The discharged oil flows into the friction part of the pin and the bearing to form a lubricating film. Ultimately, the service life of the product is extended. In other words, the greater the amount of internal pores, the more oil is contained, so the endurance life of the product is increased.

However, when the iron-copper-carbon-based sintered bearing is used in construction heavy equipment having a high surface pressure load, the internal pores may be a factor to lower the strength of the bearing.

(1) Therefore, in order for the iron-copper-carbon sintered bearing to be applied to construction heavy equipment having a high surface pressure load, a technology capable of smoothly draining the contained oil by preventing surface deformation of the sintered bearing even under high surface pressure, That is, there is an urgent need for a technology that can have improved strength than conventional bearings while maintaining the required amount of internal pores.

(2) Meanwhile, the prior art Korean Patent (Registration No .: 10-0659940) contains oil in the internal pores of the iron-copper-carbon-based sintered bearing (see "10" in FIG. 3) and the bearing (FIG. 3). The technique of forming an oil groove (see "11" in FIG. 3) of the circumferential annular pattern further on the inner circumferential surface of "10" of the present invention and storing oil in the oil groove (see "11" in FIG. 3) is known. have. Specifically, the gist of this technique is to reduce friction torque by using oil in the circumferential annular oil groove (see " 11 " in Fig. 3) at the beginning of operation, i.e., before the oil in the internal pores is supplied. And during operation, the impregnated oil is supplied from internal pores in the worn surface by the friction at the beginning of the operation, thereby reducing the friction for both the initial operation and during operation.

However, as the oil groove (see “11” in FIG. 3) has an annular pattern in the circumferential direction, it may be difficult to smoothly lubricate the oil because the oil is blocked in the longitudinal direction. In addition, both sides of the oil groove (see "11" in FIG. 5) have projections like a mountain (see "12" in FIG. 5), so that the true contact area is small, so that the initial bearing (see "10" in FIG. 3) is adequate. As the surface pressure to be made increases considerably, deformation and wear may be severely generated on the inner circumferential surface of the bearing (see "10" in FIG. 3). In addition, due to deformation and wear, debris generated on the inner circumferential surface of the bearing (see "10" in FIG. 3) is not leaked to the outside, and the oil groove (see "11" in FIG. 3) has a plurality of mutually independent annular patterns. As a result, it is not discharged to the outside and is accumulated in the circumferential annular oil groove (see “11” in FIG. 3), which may ultimately block internal pores and adversely affect lubrication.

(3) On the other hand, the Korean patent (Registration No .: 10-0261369) and the Korean Patent (Registration No .: 10-0244584) regulate only the viscosity of the oils contained, thereby defining the types of oils used in the construction equipment of high surface pressure. Doing. However, this technique does not consider the destruction of the lubricating film against the high surface pressure of heavy construction equipment. Therefore, there is an urgent need for a method of improving the characteristics of the lubrication film under high surface pressure, that is, the extreme pressure characteristic, and if a technology capable of improving the extreme pressure characteristic is developed, the oil of the prior art The regulation on viscosity will be meaningless.

The present invention is to solve the problems of the prior art, the technical problem of the present invention is to improve the strength, extreme pressure characteristics, and wear resistance properties, and ultimately to increase the endurance life and sintered bearing and its manufacture To provide a way.

Another technical problem of the present invention is to provide a sintered bearing that can prevent the internal pores blocked during operation.

In order to achieve the above object, the sintered bearing according to an embodiment of the present invention includes a body, and the body is iron that is responsible for the strength of the body to the base of the body, and the rapid discharge and strength characteristics of friction heat Copper to reinforce, carbon to diffuse to the iron to harden the iron during heat treatment, and to improve the strength characteristics or lubrication characteristics (extreme pressure characteristics) of the body (lubrication through pore enlargement when maintaining the same strength Carbon nanoparticles (CNTs) dispersed in the body to enhance the frictional properties, while improving the properties.

In addition, the carbon nanotube (CNT) particles may occupy 0.01 to 5.0% by weight based on the total weight ratio in the body.

Further, the copper occupies 15 to 25% by weight based on the total weight ratio in the body, the carbon occupies 0.5 to 1.0% by weight based on the total weight ratio in the body, and the iron is in the body It can occupy the rest.

In addition, the body is formed with internal pores that may contain oil, the internal pores may have a volume of 12 to 25% by volume based on the total volume ratio.

In addition, a plurality of oil grooves having a cross spiral shape intersecting with each other may be formed on the contact surface of the body with the mating member.

In addition, the depth of the plurality of cross-shaped oil grooves is 1 ~ 20um, the interval is within 0.01 ~ 1mm, and can be processed by a honing machine or a reciprocating turning machine.

On the other hand, the manufacturing method of the sintered bearing according to an embodiment of the present invention comprises the steps of mixing the copper component and the CNT particles to form an initial mixed powder; Mixing the iron component and the carbon component with the initial mixture to form a final mixed powder; Molding the final mixed powder into a shaped body; Sintering the molded body into a sintered body; Containing oil in the sintered body; And shape-processing the sintered body containing the oil.

In addition, the carbon nanotube (CNT) particles occupy 0.01 to 5.0% by weight based on the total weight ratio in the body, the copper occupies 15 to 25% by weight based on the total weight ratio in the body, the carbon Is occupied 0.5 to 1.0% by weight based on the total weight ratio in the body, and the iron may occupy the rest in the body.

In addition, in the forming step, the body is formed with internal pores that may contain oil, the internal pores may have a 12 to 25% by volume based on the total volume ratio.

In addition, in the step of making the initial mixed powder, a salt solution reduction method may be used to disperse the CNT particles in the copper powder.

In addition, the method of manufacturing a sintered bearing according to an embodiment of the present invention may further include forming a plurality of oil grooves having a cross spiral shape on the inner circumferential surface of the molded body after the shape processing. .

In addition, the plurality of oil grooves of the crossed spiral shape may be processed by a honing machine or a reciprocating turning machine.

In addition, the manufacturing method of the sintered bearing according to an embodiment of the present invention may further comprise the step of heat-treating the sintered body between the step of sintering and impregnating the oil.

On the other hand, the sintered bearing according to another embodiment of the present invention includes an annular body, and a plurality of oil grooves having a cross spiral shape are formed on the contact surface with the mating member of the body.

As described above, the sintered bearing according to an embodiment of the present invention and a manufacturing method thereof may have the following effects.

According to one embodiment of the invention, as the CNT is added to the body, it is possible to secure the characteristics of the fiber-reinforced composite material to improve the strength of the sintered bearing. In other words, CNTs in the form of nanofibers of fine fibers reinforce and connect the contact neck of the sintered particles, thereby improving the strength of the sintered bearing. In addition, the friction characteristics of the bearing can be improved by the excellent sliding characteristics of the CNT, and furthermore, the bearing can withstand the boundary lubrication conditions and the extreme pressure lubrication conditions that cannot be tolerated only by the containing oil with the improvement of the extreme pressure characteristics. In addition, since the strength of the body is improved by CNTs, the amount of internal pores may be relatively increased by relatively decreasing the density of the body under the same strength condition.

In addition, according to one embodiment of the present invention, as a plurality of oil grooves having a cross-helix shape is formed on the inner circumferential surface of the body, it is to stay in each annular oil groove formed along the circumferential direction of the body as in the prior art Rather, the flow of oil in the longitudinal direction of the bearing is induced as it flows into the plurality of oil grooves and the oil is spread evenly as a whole. As a result, since the outflow of oil is promoted through the plurality of oil grooves, breakage of the lubricating film that may occur due to the lack of oil at the beginning of operation may be minimized. Furthermore, since oil spillage is promoted, normal debris generated by friction between the shaft and the bearing can be smoothly discharged to the outside, thereby preventing internal pores from being blocked by the normal abrasive. That is, since oil is smoothly supplied from internal pores during operation, friction between the bearing and the shaft can be minimized.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

1 is a perspective view showing a sintered bearing according to an embodiment of the present invention.

The iron-copper-carbon-CNT-based sintered bearing according to the embodiment of the present invention, as shown in FIG. 1, includes a body 100, and the body 100 is known as the strength of the body 100. Iron, responsible for the rapid discharge of frictional heat and strengthening the strength characteristics of the body 100, carbon that serves to harden the iron during heat treatment by diffusing to iron, and improving the strength characteristics of the body 100 Or carbon nanotube (CNT) particles dispersed and strengthened in the body 100 to improve the frictional characteristics while providing an improvement in the lubrication characteristics (improving the lubrication characteristics through pore enlargement when maintaining the same strength).

In particular, as the CNT is added to the body 100, the body 100 has the following characteristics.

As the CNT is added to the body 100, it is possible to secure the characteristics of the fiber-reinforced composite material to improve the strength of the sintered bearing. In other words, CNTs in the form of nanofibers of fine fibers may reinforce and connect the contact neck of the sintered particles with the particles, thereby improving the strength of the body 100. In addition, the friction characteristics of the bearing can be improved by the excellent sliding characteristics of the CNT, and furthermore, the boundary of the state which cannot be endured only by the oil contained in the pores that can be included in the conventional general sintered bearing with the improvement of the extreme pressure characteristics. The bearing can withstand the lubrication conditions and extreme pressure lubrication conditions, but the addition of CNT improves the strength of the body 100, thus reducing the density of the body 100 relatively under the same strength conditions in the related art. (Ie the amount of oil in the pores) can be increased relatively.

Hereinafter, with reference to Table 1, each composition constituting the body 100 will be described in more detail.

Fe Cu C CNT Bal. 15-25 0.5-1.0 0.01 ~ 1.0

Iron serves to secure the strength of the bearing as a base portion, the rest of each composition described later is included in the body (100).

Copper serves to quickly discharge frictional heat of the body 100 and at the same time to strengthen the strength characteristics of the body 100, it was shown by the experiment that it is preferable to be composed of 15 to 25% by weight based on the total weight ratio . That is, according to the experiment, copper has a lower melting point, better lubricity, a larger diffusion coefficient, easier diffusion, and a larger heat transfer coefficient. During the sintering process, since it is almost dissolved into the iron structure of the body 100, the remaining copper is insufficient so that the fin and the sintered bearing do not sufficiently release the frictional heat generated at the contact. It was found that the effect of suppressing the occurrence of the bearing and the shaft sticking together when insufficiently removed was insufficient. On the contrary, when the added amount was 25% by weight or more, it was found that the amount of iron, which was relatively relatively low, was insufficient, so that it was difficult to obtain a load-bearing effect. Accordingly, the optimum amount of copper described above should be added so that the frictional heat dissipation effect of the bearing, the effect of suppressing the occurrence of sintering, and the load-bearing effect can be optimally obtained. In addition, experiments showed that the bonding of the composition was the best when copper was added at the above 20% by weight.

Carbon serves to cure iron when it is diffused into iron and heat-treated, and it has been shown by experiment that the composition is preferably 0.5 to 1.0% by weight based on the total weight ratio. That is, according to the experiment, carbon forms a pearlite by being dissolved in iron as a base and helps to form hard martensite after heat treatment, but if the addition amount is 0.5 wt% or less, martensite formation after heat treatment It was found to be lacking, and if the added amount was more than 1.0% by weight, it was found that the tissue could be brittle due to the formation of coarse reticulum cementite. Accordingly, it would be desirable to add the optimal amount of carbon described above to form full pearlite and to form hard martensite after heat treatment.

The CNT is dispersed and strengthened at the base to improve strength and friction characteristics of the body 100, and it is experimentally shown that the composition is preferably composed of 0.01 to 5.0% by weight based on the total weight ratio. That is, according to the experiment, since the CNTs have a fibrous shape, the particles (iron or copper) and the particles (iron or copper) are firmly connected, so that the strength of the body 100 is improved and the sliding property is exposed by the exposed part of the surface. However, if the added amount is 0.01% by weight or less, the amount is insignificant and the contribution to improving the overall strength of the body 100 is shown to be small (that is, CNT is not present in a part of the body, so that the particles and particles When the addition amount is 5.0 wt% or more, it is found that failure to secure the sintering density by inhibiting the sintering property in the step of sintering the molded body, 1.0 wt% is confirmed as the optimal amount It became. Accordingly, in order to improve the strength and the friction characteristics of the body 100, it will be desirable to add the above-described optimal amount of CNTs. In addition, the friction characteristics of the bearing can be improved by the excellent sliding characteristics of the CNT, and furthermore, the boundary lubrication in a state in which the oil contained in the pores that can be included in the conventional sintered bearing with the improvement of the extreme pressure characteristics can not be tolerated. Bearings can withstand conditions and extreme pressure lubrication.

Hereinafter, the internal pores 101 formed in the body 100 will be described in detail.

In the body 100 made of the above-described composition and completed molding or sintering, internal pores 101 may be formed, which may contain oil. At this time, it was shown by experiment that the internal pore 101 is preferably from 12 to 25% by volume based on the total volume ratio. That is, according to the experiment, when the internal pore 101 is 12 vol% or less, the amount of oil contained is small, so the endurance life is sharply reduced, and when the internal pore 101 is 25 vol% or more, the body 100 ), The intensity of the abruptly curved curve.

In particular, in order to form the internal pores 101 of 12 to 25% by volume in the body 100, in the molding process described later, the molding pressure and the composition mixing ratio should be maintained properly.

Hereinafter, referring to FIGS. 2 to 5, a plurality of oil grooves 110 having a cross spiral shape formed on the inner circumferential surface of the body 100 (refer to “120” in FIG. 4) will be described in detail.

Figure 2 is a cross-sectional view II-II of Figure 1 for showing the shape of the oil groove formed in the sintered bearing according to an embodiment of the present invention, Figure 3 is the shape of the oil groove used in the prior art the oil groove of Figure 2 It is a figure for comparing with the shape of.

FIG. 4 is an enlarged view of portion “A” of FIG. 2 for specifically showing an inner circumferential surface cross section (in the case of a honing machine) of a sintered bearing according to an embodiment of the present invention, and FIG. 5 is an inner circumferential surface of FIG. It is an enlarged view of the "B" part of FIG. 3 for comparing with a cross section.

After the oil is contained in the internal pores 101 of the sintered body 100, as shown in FIG. 2, the contact surface of the body 100 with a mating member (not shown) (for example, a pin or shaft) is provided. A plurality of oil grooves 110 having cross spiral shapes that cross each other may be formed. When the plurality of oil grooves 110 have an intersecting shape intersecting with each other, each annular oil groove formed in the circumferential direction of the body (see "10" in FIG. 3) as in the prior art (see "11" in FIG. 3). Rather than staying in oil, the oil flows into the plurality of oil grooves 110, leading to flow of oil in the longitudinal direction of the body 100, and spreading the oil evenly. As a result, since the outflow of oil is promoted through the plurality of oil grooves 110, the destruction of the lubricating film that may occur due to the lack of oil at the beginning of operation may be minimized. Furthermore, since oil spillage is promoted, normal debris generated by friction between the shaft (not shown) and the bearing (see “100” in FIG. 1) can be smoothly discharged to the outside. As a result, it is possible to prevent the internal pores 101 from being blocked. That is, since oil is smoothly supplied from the internal pores 101 during operation, friction between the bearing (see “100” in FIG. 1) and the shaft (not shown) may be minimized.

In particular, the plurality of cross spiral oil grooves 110 may be machined by a reciprocating turning machine (not shown) using a tool such as a honing machine (not shown) or a plexhorn tool. Among these, the honing machine (not shown) polishes the sharp projections of the prior art formed in the oil groove 110 (see reference numeral “12” in FIG. 6 and the inner circumferential roughness measurement graph in FIG. 7). As shown, the inner circumferential surface 120 of the body 100 except for the oil groove 110 (the upper surface of the portion projecting inwardly from the bottom of the oil groove) becomes flat (that is, the true contact surface becomes large). Unlike the initial operation, wear does not occur badly, which can be confirmed through the graph of the inner circumferential roughness measurement of FIG. 5.

Hereinafter, a method of manufacturing a sintered bearing according to an embodiment of the present invention will be described in detail with reference to FIG. 8.

8 is a flowchart illustrating a process of manufacturing a sintered bearing according to an embodiment of the present invention.

First, the copper component and the CNT particles are mixed with each other to form an initial mixed powder (S110).

In order to use CNTs as added particles for improving the strength, the CNTs must be uniformly dispersed in iron, copper, and carbon powders. When mixed with a dry mixer for powder metallurgy, CNT segregation occurs because CNTs are so fine particles that they cannot be used. Therefore, in order to solve the CNT segregation phenomenon, CNT was first dispersed in copper powder to make a CNT composite copper powder, which is an initial mixed powder, and then mixed with other elements such as iron and carbon powder in a mixer, whereby A uniformly dispersed final mixed powder could be obtained. In other words, although it is not easy to uniformly disperse the CNTs of nanoparticles in iron, copper and carbon powders, the experiments show that the CNTs are uniformly mixed in the bearings made of powder metallurgy when manufactured by the method of the present invention. Observed through.

Second, iron powder, copper powder, and carbon powder are mixed with the initial mixture to form a final mixed powder (S120).

As described above, in a state where CNT composite copper powder, which is an initial mixed powder, is made by dispersing CNT in copper powder, it is mixed with iron and carbon powder in a mixer to form a final mixed powder.

Third, the final mixed powder is molded by a powder molding press (S130).

When molding the final mixed powder, the pressure of the molding press shows a proportional relationship with the density of the molded body, which serves to determine the amount of internal pores 101 of the body 100. Based on this, the molding pressure is adjusted using a molding press to obtain 12 to 25% by volume of internal pores 101 based on the total volume ratio of the molded body, and optimally, 18% by volume of internal pores can be obtained. It was found to be desirable to use sexual coercion. That is, when the internal pore 101 is 12 vol% or less, the amount of oil contained is small and the durability life is rapidly decreased. When the internal pore 101 is 25 vol% or more, the strength of the body 100 is increased. Shows a sharp downward curve. Therefore, in order to obtain the internal pores 101 of the above-mentioned volume, it was found that the molded body is preferably pressed to form the internal pores 101 of 12 to 25% by volume.

Fourth, the molded body is sintered using a sintering furnace (furnace) (S140).

The molded article is molded is sintered to ensure strength. For sintering is carried out in a reducing atmosphere or a vacuum atmosphere, the sintering temperature was found to be set to 1,013 ~ 1,200 ℃ it can be seen through experiments. That is, when the sintering temperature is less than 1013 ℃, that is, less than 1,013 ℃, which is the temperature at which the liquid phase appears, the sintering did not occur, and when the sintering temperature is higher than 1,200 ℃, the copper present in the molded body The flow is so good that the internal pores 101 are coalesced with each other, and by this phenomenon, the area where the large pores 101 are formed in the body 100 has been shown to have a low hardness.

Fifth, the oil is contained in the sintered body (S160).

The internal pore 101 is formed in the body 100 where sintering is completed, and oil is contained in the internal pore 101. It is preferable to use gear oil for the oil contained, and it is possible to use mineral oil-based or synthetic oil-based ones, but it is usually advantageous to use a synthetic oil-based gear oil for the shaft and bearing systems of heavy construction equipment.

Sixth, shape processing is performed to the contained sintered compact (S170).

The contained sintered body is subjected to a turning and polishing process to secure the shape of the oil inlet and the desired size and roughness.

Furthermore, in the manufacturing method of the sintered bearing according to the embodiment of the present invention, the sintered body is heat-treated between the fourth process (S140) (sintering process) and the fifth process (S160) (process containing oil). It may further comprise a step (see "S150" in Figure 6). In order to improve the strength of the material, it can be heat-treated before the oil is contained, and the general quenching and tempering are performed, and this heat treatment process can be eliminated depending on the required material strength.

In addition, in the manufacturing method of the sintered bearing according to the embodiment of the present invention, after the sixth step (S170) (shape processing), a plurality of oil grooves 110 having a cross-helical shape intersecting each other on the inner circumferential surface of the sintered body are formed. The process may further include the step (see S180 of FIG. 6).

When the plurality of cross spiral oil grooves 110 are further formed, each annular oil groove formed along the circumferential direction of the body (see “10” in FIG. 3) as in the related art (see “11” in FIG. 3). Rather than staying in oil, the oil flows into the plurality of oil grooves 110, leading to flow of oil in the longitudinal direction of the body 100, and spreading the oil evenly. As a result, since the outflow of oil is promoted through the plurality of oil grooves 110, the destruction of the lubricating film that may occur due to the lack of oil at the beginning of operation may be minimized.

Furthermore, since oil spillage is promoted, normal debris generated by friction between the shaft (not shown) and the bearing (see “100” in FIG. 1) can be smoothly discharged to the outside. As a result, it is possible to prevent the internal pores 101 from being blocked. That is, since oil is smoothly supplied from the internal pores 101 during operation, friction between the bearing (see “100” in FIG. 1) and the shaft (not shown) may be minimized.

In particular, the plurality of cross spiral oil grooves 110 may be processed by a honing machine (not shown) or a reciprocating turning machine (not shown). Among these, in the case of the honing machine (not shown), since the sharp projection (see "12" in FIG. 6) of the prior art formed in the oil groove 110 is polished, as shown in the enlarged view of FIG. In addition, since the inner circumferential surface 120 of the body 100 except for the oil groove 110 is formed flat (that is, the true contact surface becomes larger), wear does not occur badly during initial operation unlike the conventional art (roughness of FIG. 5). Also found in the measurement graphs).

As described above, the sintered bearing according to an embodiment of the present invention and a manufacturing method thereof may have the following effects.

According to one embodiment of the invention, as the CNT is added to the body 100, it is possible to improve the strength of the bearing. In other words, CNTs in the form of fibrils connect the particles to the particles, thereby improving the strength of the bearing. In addition, the sliding properties of the CNTs can improve the friction characteristics of the bearings. Furthermore, the extreme pressure of the CNTs allows the bearing to withstand the boundary lubrication and the extreme pressure lubrication in a state that the oil itself cannot withstand. In addition, since the strength of the body 100 is improved by the CNT, the density of the body 100 may be relatively reduced under the same strength condition in the related art, thereby increasing the amount of the internal pores 101 relatively.

In addition, according to an embodiment of the present invention, when the plurality of oil grooves 110 of the cross spiral shape is further formed,

As shown in the related art, oil does not stay in each annular oil groove (see “11” in FIG. 3) formed along the circumferential direction of the body (see “10” in FIG. 3), and flows into a plurality of oil grooves 110. The flow of oil in the longitudinal direction of the body 100 is induced and the oil is spread evenly throughout. As a result, since the outflow of oil is promoted through the plurality of oil grooves 110, a phenomenon in which the initial operating surface pressure is increased can be minimized. Furthermore, since oil spillage is promoted, normal debris generated by friction between the shaft (not shown) and the bearing (see “100” in FIG. 1) can be smoothly discharged to the outside. As a result, it is possible to prevent the internal pores 101 from being blocked. That is, since oil is smoothly supplied from the internal pores 101 during operation, friction between the bearing (see “100” in FIG. 1) and the shaft (not shown) may be minimized.

Although the preferred embodiment of the present invention has been described above, the scope of the present invention is not limited thereto, and various modifications and improvements using the basic concept defined in the claims also belong to the scope of the present invention.

1 is a perspective view showing an iron-copper-carbon-CNT-based sintered bearing according to an embodiment of the present invention.

FIG. 2 is a II-II cross-sectional view of FIG. 1 for illustrating a shape of an oil groove formed in a sintered bearing according to an embodiment of the present invention.

Figure 3 is a view for comparing the shape of the oil groove of Figure 2 with the shape of the oil groove used in the sintered bearing according to the prior art.

FIG. 4 is an enlarged view of portion “A” of FIG. 2 specifically illustrating an inner circumferential cross section of a sintered bearing whose inner circumferential surface is processed by a honing machine according to an embodiment of the present invention.

FIG. 5 shows a graph of surface roughness measurements of the inner circumferential surface of the sintered bearing whose inner circumferential surface is processed by a honing machine according to an embodiment of the present invention.

6 is an enlarged view of a portion “B” of FIG. 3.

7 shows a graph of surface roughness measurements of the inner circumferential surface of the sintered bearing whose inner circumferential surface is processed by a honing machine according to an embodiment of the present invention.

8 is a flowchart illustrating a process of manufacturing a sintered bearing according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

100: body 101: internal pores:

110: oil groove

Claims (16)

In sintered bearings, Including a body, The body is Iron to the base of the body responsible for the strength of the body, Copper to enhance the rapid discharge of frictional heat and strength characteristics, Carbon which diffuses into the iron and serves to cure the iron during heat treatment; and Sintered bearing comprising a CNT particles (Carbon Nano Tube) to be dispersed in the body of the body to the first dispersed in the powder of the copper in the body to form an initial mixed powder. In claim 1, The CNT (Carbon Nano Tube) particles occupy 0.01 to 1.0% by weight based on the total weight ratio in the body The copper occupies 15 to 25% by weight based on the total weight ratio in the body, The carbon occupies 0.5 to 1.0% by weight based on the total weight ratio in the body, The iron occupies the rest of the body, and The body is formed with internal pores that may contain oil, The internal pore is a sintered bearing having 12 to 25% by volume based on the total volume ratio. delete delete The method of claim 1 or 2, Sintered bearings are formed in the contact surface with the mating member of the body a plurality of oil grooves of the cross spiral shape to cross each other. In claim 5, Sintered bearings are processed by the honing machine so that the plurality of the cross-helical oil grooves are formed to have a flat inner peripheral surface of the body except the oil grooves. In claim 5, The sintered bearing of the cross-helical oil groove is processed by a reciprocating turning machine. Intermixing the copper component and the CNT particles to form an initial mixed powder; Mixing the iron component and the carbon component with the initial mixture to form a final mixed powder; Molding the final mixed powder into a shaped body; Sintering the molded body into a sintered body; Containing oil in the sintered body; And A method of manufacturing a sintered bearing comprising the step of shaping the oil-containing sintered body. In claim 8, The CNT (Carbon Nano Tube) particles occupy 0.01 to 1.0% by weight based on the total weight ratio in the body, The copper occupies 15 to 25% by weight based on the total weight ratio in the body, The carbon occupies 0.5 to 1.0% by weight based on the total weight ratio in the body, The iron occupies the rest of the body, and In the forming step, the body is formed with internal pores that may contain oil, the internal pores manufacturing method of the sintered bearing having 12 to 25% by volume based on the total volume ratio. In claim 8, Between the sintering step and the step of containing the oil, The method of manufacturing a sintered bearing further comprising the step of heat treating the sintered body. In claim 8, In the step of making the initial mixed powder, Method for producing a sintered bearing using a salt solution reduction method to disperse the CNT particles in the copper powder. The method according to any one of claims 8 to 11, After the shape processing step, The method of manufacturing a sintered bearing further comprising the step of forming a plurality of cross-shaped oil grooves intersecting each other on the inner peripheral surface of the sintered body. In claim 12, Between the sintering step and the step of containing the oil, The method of manufacturing a sintered bearing further comprising the step of heat-treating the sintered body. In claim 12, The plurality of oil grooves of the cross-helix shape is processed by a honing machine so that the inner peripheral surface of the body except the oil groove is formed flat. In claim 12, And said plurality of oil grooves of said cross-helical shape are processed by a reciprocating turning machine. delete

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