KR101540036B1 - A Sintered Body having Dual Ring Structure and a Manufacturing Method for the same - Google Patents

Abstract

The present invention relates to an annular sintered body, and more particularly, it is used in a driving part of an industrial machine or a construction equipment machine so as to smoothly remove harmful substances from the shaft and the inside of the bearing, The present invention is useful for constructing a new type of sintered oilless bushing bearing capable of smooth sliding by increasing the prevention effect of frictional heat by reducing frictional force, and particularly suitable for use in high-load and low-speed bearings. More particularly, The present invention relates to a dual-sided annular sintered body made of a sintered metal sintered body of an inner circumferential portion and an outer circumferential portion, and a method of manufacturing the same.

Description

FIELD OF THE INVENTION [0001] The present invention relates to an annular sintered body having a dual structure and a method for manufacturing the sintered body,

[0001] The present invention relates to an annular sintered body constituting a cylindrical sintered bearing widely used in sliding parts of various industrial machines, and more particularly, to an annular sintered body having a double structure having different inner and outer peripheral characteristics to optimize load- To an annular sintered body and a method of manufacturing the sintered body.

The present invention relates to an annular sintered body, and more particularly, to an annular sintered body, which is used in a driving part of an industrial machine or a construction equipment machine, and which can smoothly remove harmful substances from the shaft and the inside of the bearing, The present invention relates to an annular sintered body suitable for use in high-load and low-speed bearings. The present invention relates to an annular sintered body suitable for use in high-speed low-speed bearings.

Generally, sliding bearings are mainly used for shaft rotating parts of industrial machines or construction machines, and the shaft rotating parts include rotating shafts and bush bearings.

The above-mentioned sliding bearings should have excellent abrasion resistance, corrosion resistance, etc. in consideration of a special special environment such as sand or a mixture of fine minerals and seawater owing to characteristics of the place of use thereof.

Accordingly, the bush bearing is constructed to be able to have wear resistance and corrosion resistance from harmful substances introduced between the shaft and the bush bearing by using carbon steel that can increase the hardness of the inner and outer diameters through heat treatment.

However, since conventional bush bearings require continuous oil supply for smooth lubrication, recently, a new type of sintered oilless bearings have been developed and widely used.

This sintered oil-less bearing is a bearing made by sintering iron-copper-carbon powder. It is used together with a pin (or rotating shaft) in many joints included in industrial machinery and construction machinery, And also serves to reduce frictional resistance with the pin (or rotating shaft).

This iron-copper-carbon-based sintered oil-less bearing generally has an inner pore of about 20 vol%, and the inner pore contains oil. This oil is expanded inside the bearing due to frictional heat generated when the pin (rotary shaft) and the bearing rub against each other, and then discharged to the outside of the bearing. The discharged oil flows to the friction portion between the pin (rotary shaft) and the bearing Lubricating film is formed, so that the durability life of the rotary shaft product ultimately supported by the bearing is prolonged. That is, the more the amount of the internal pores, the more oil is contained, so the service life of the rotating shaft product supported by the sintered oil-less bearing is increased.

The inner sintered body of the cylindrical sintered oilless bearing according to the prior art should use expensive copper or copper alloy powder so as to provide the necessary internal pores on the basis of the lubrication characteristics. However, the inner sintered body of the cylindrical sintered oilless bearing The outer peripheral sintered body is provided with the necessary pores even though the pores included therein do not provide a lubrication characteristic to the shaft rotation portion and are merely a portion that provides a function of maintaining the shape and strength of the cylindrical sintered oilless bearing In addition, there is a problem in that the production cost is high because it has an unreasonable point of being manufactured using expensive copper or copper alloy powder. In addition, in order to improve durability and corrosion resistance, a metal bush is separately provided on the outer side of the sintered body And sinter bonding) There is a problem that it provides an additional factor of rising production cost.

On the other hand, as illustrated in FIG. 1, the molded body or the sintered body 12 of the second metal powder is press-fitted into the inner diameter of the metal bush 11, and the second metal powder is press- (See Korean Patent No. 10-0286246 and Korean Patent Laid-open No. 10-2008-0082832), and the boundary surfaces are joined to form the cylindrical sintered bearing 10, the sintered body 11 And the interface between the metal bush 12 on the outer circumferential surface thereof and the interface between the metal bush 12 and the metal bush 12 on the outer circumferential surface thereof.

An object of the present invention is to solve the problems of the prior art, and an object of the present invention is to provide an annular sintered body used for constructing a cylindrical sintered oil-less bearing, wherein the material constituting the inner annular sintered body and the outer- The outer peripheral portion of the cylindrical sintered oilless bearing provides a good lubricating property to the inner peripheral portion constituting the cylindrical sintered oilless bearing and the outer peripheral portion of the cylindrical sintered oilless bearing, It is an object of the present invention to provide a double sided annular sintered body suitable for high load and low speed bearings even at a low manufacturing cost by providing a good rigidity, durability and corrosion resistance, and further to provide a method for manufacturing such a double sided annular sintered body will be.

In order to achieve the above object, according to a preferred embodiment of the present invention,

An annular sintered body of a dissimilar metal with different metal powder composition in inner and outer circumference,

The first cylindrical formed body formed of the first metal powder is first press-formed with the initial formed body and the inner cylindrical body is pressed together with the second cylindrical shaped body as the second metal powder to form a first cylindrical formed body A first cylindrical sintered body forming an outer circumferential portion when the first cylindrical formed body and the second cylindrical formed body are sintered and bonded to form an annular sintered body having a double structure; And

A second cylindrical metal body having a powder composition different from that of the first metal powder on an inner surface of an initial formed body of the first cylindrical formed body forming the first cylindrical sintered body, And a second cylindrical sintered body which is simultaneously sintered with the first cylindrical sintered body and diffused and joined to the inner side surface of the first cylindrical sintered body so as to form an inner peripheral portion of a dual structure annular sintered body in surface contact with the member. Sintered body.

Here, in order to construct a double-structure annular sintered body having different structural characteristics such as internal porosity in the second cylindrical sintered body of the inner peripheral portion and the first cylindrical sintered body of the outer peripheral portion, the first cylindrical formed body of the outer peripheral portion has a thickness of 6.5 to 7.5 g / Cm < 3 >, and the two cylindrical formed bodies on the inner side thereof are preferably formed in a powder density of 5.5 to 6.5 g / cm < 3 > which is relatively lower than the powder density of the first cylindrical formed body, In the first molding step in which only the first cylindrical formed body is powder-formed, the initial formed body of the first cylindrical formed body is preferably molded to have a powder density of 4.0 to 5.0 g / cm < 3 >, and the two cylindrical formed bodies It is preferred that the powder density be reached to 6.5 to 7.5 g / cm < 3 >

As described above, the powder density of the first cylindrical formed body having a relatively high forming density of the outer peripheral portion is advantageous in view of providing a relatively low internal porosity in the double-structure annular sintered body while providing better strength characteristics, durability and corrosion resistance, The powder density of the second cylindrical formed body having a relatively low forming density of the main portion is higher than that of the double-structured annular sintered body in terms of providing a relatively high internal porosity in the inner side portion in surface contact with the sliding member, Do.

On the other hand, the first metal powder may contain 0.3 to 1.3% by weight of graphite based on the weight ratio; 0.1% by weight to 3.0% by weight of a bonding agent as at least one bonding agent selected from the group consisting of copper, nickel, manganese and molybdenum nitride, and iron to the remaining known portions.

Also, the second metal powder having a powder composition different from that of the first metal powder may be 15 to 30 wt% of copper or copper alloy based on the weight ratio; 0.3% to 1.3% by weight of graphite; And it is preferable that iron is contained in the base portion. Furthermore, when a copper alloy is selected, the copper alloy may be any one selected from a bronze alloy (Cu-Sn) or a brass alloy (Cu-Zn).

The present invention also provides, from yet another aspect, a method for producing an annular sintered body having a dual structure according to the present invention,

A metal powder preparation step of preparing a second metal powder having a powder composition different from that of the first metal powder and the powder composition of the first metal powder;

A first cylindrical shaped body initial molding step of forming a first cylindrical shaped body by applying a first metal powder into a space between an outer annular die of the first molding die and an inner central core and press-molding the same;

The first cylindrical formed body is inserted into the outer portion of the space between the outer annular die and the inner central core of the second molding die and the inner cylindrical core of the first cylindrical formed body The second metal powder is injected and pressurized so as to form a second cylindrical formed body in the space portion to form a cylindrical formed body of the first cylindrical formed body and the second cylindrical shaped body, wherein the first cylindrical shaped body reaches the first powder density, Molding the cylindrical shaped body to pressurize the second cylindrical shaped body on its inner side to reach a second powder density relatively lower than a first powder density of the first cylindrical shaped body; And

A first cylindrical formed body and a second cylindrical formed body which is press-formed at a relatively lower powder density than the first cylindrical formed body on an inner surface of the first cylindrical formed body, and sintering the cylindrical formed body to join the annular sintered body having a dual structure .

Here, the first powder density for the first cylindrical formed body is preferably set to a powder density of 6.5 to 7.5 g / cm 3, preferably 7.0 g / cm 3, and the second cylindrical formed body Is preferably set to a powder density of 5.0 to 6.5 g / cm 3, preferably 6.3 / cm 3, which is relatively lower than the first powder density.

Of course, the first cylindrical formed body is formed through two steps of the initial forming step of the first cylindrical formed body and the cylindrical formed composite forming step to form the cylindrical composite formed body. The first cylindrical formed body is formed by the first cylindrical formed body It is preferable that the initial formed body of the first cylindrical formed body is formed at a powder density of 4.0 to 5.0 g / cm < 3 >.

Here, the first metal powder may contain 0.3 to 1.3% by weight of graphite, based on the weight ratio, of the first metal powder; 0.1% by weight to 3.0% by weight of a bonding agent as at least one bonding agent selected from the group consisting of copper, nickel, manganese, and molybdenum nitride, and iron as the remaining base portion, From 15% to 30% by weight of copper or copper alloy based on the weight ratio; 0.3% to 1.3% by weight of graphite; And it is preferable that iron is contained in the base portion. Furthermore, when a copper alloy is selected, the copper alloy may be any one selected from a bronze alloy (Cu-Sn) or a brass alloy (Cu-Zn).

In the bonding sintering step, the bonding sintering temperature is 950 ° C to 1200 ° C; The bonding sintering time is from 10 minutes to 50 minutes; The bonding sintering atmosphere may be a reducing atmosphere or a vacuum atmosphere.

Further, according to a further aspect of the present invention, there is provided a method for manufacturing a cylindrical sintered oil-less bearing using a double-structure annular sintered body manufactured through the above-

Heat treating the annular sintered body having a dual structure;

Impregnating the heat-treated annular sintered body of the double structure with oil; And

The present invention also provides a method of manufacturing a cylindrical sintered oil-less bearing, which further comprises cutting the annular sintered body having the double structure containing the oil.

The heat treatment may be performed by any one of high frequency heat treatment, quenching, carburizing or nitriding heat treatment.

Further, in the step of impregnating the oil, the oil impregnation temperature may be 60 to 100 DEG C, and the oil impregnation atmosphere may be a vacuum atmosphere or an air atmosphere.

As described above, according to the double-structure annular sintered body provided in accordance with the present invention, only the material forming the inner peripheral sintered body to provide good lubricity when constituting the cylindrical sintered oil-less bearing is a large amount of expensive copper or copper alloy And the outer circumferential portion is formed only of the first metal powder at a lower cost so as to lower the material cost and the overall manufacturing cost while maintaining the structural characteristics such as the inner porosity in the inner peripheral sintered body and the outer peripheral sintered body, By adjusting the molding density, it is possible to obtain the effect of providing good lubrication characteristics to the inner circumference portion with a low manufacturing cost and providing better rigidity, durability and corrosion resistance to the outer circumferential portion.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of a conventional cylindrical sintered oil-less bearing; FIG.
FIG. 2 is a schematic view showing a dual structure annular sintered body according to an embodiment of the present invention.
FIG. 3A is an exploded perspective view showing a first forming mold for forming a first cylindrical formed body constituting a double-structure annular sintered body according to an embodiment of the present invention, FIG. 3B is an exploded perspective view showing an assembled state of the first forming mold Sectional view.
4A and 4B are views sequentially illustrating a process of forming an initial formed body by press-forming a first cylindrical formed body using a first metal powder as a first forming mold.
Fig. 5A is an exploded perspective view showing a second forming mold for forming a second cylindrical formed body constituting a double-structure annular sintered body according to an embodiment of the present invention on the inner surface of a first cylindrical formed body, and Fig. 2 is a cross-sectional view showing an assembled state of the molding die and the first cylindrical formed body.
6A and 6B are views sequentially showing a process of press-molding a cylindrical composite formed article of a first cylindrical formed body and a second cylindrical formed body on the inner side thereof using a second metal powder as a second forming mold.
FIG. 7 is a flowchart showing a preferred embodiment of a method for manufacturing a double-sided annular sintered body according to the present invention and a method for manufacturing a cylindrical oilless sintered bearing suitable for a high-load low-speed bearing using the same.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

FIG. 2 is a schematic view showing a dual structure annular sintered body according to an embodiment of the present invention.

2, the double-structure annular sintered body 100 according to the embodiment of the present invention is first press-formed into an initial formed body 110a of a first cylindrical formed body formed of a first metal powder, The first cylindrical formed body 110 and the second cylindrical formed body 120 are pressed together when the second cylindrical formed body 120 is further press-formed as a second metal powder on the inner side surface thereof to form the first cylindrical formed body 110, A first cylindrical sintered body 110 forming an outer periphery when the annular sintered body 100 having a dual structure is formed; The second cylindrical shaped body 120 is formed on the inner surface of the first formed body 110a of the first cylindrical shaped body 110 forming the first cylindrical sintered body 110 as a second metal powder having a powder composition different from that of the first metal powder. The sintered body 110 is sintered at the same time as the first cylindrical sintered body 110 so as to form an inner peripheral portion of the double-sided annular sintered body 100 which is in contact with the relative sliding member, And a second cylindrical sintered body 120 which is diffusion-bonded to the side surfaces of the first and second cylindrical sintered bodies.

And, although a double-structure annular sintered body of various sizes can be made and used in accordance with the present invention, one preferred embodiment having the dimensions illustrated in FIG. 2 will be described to facilitate an understanding of the present invention.

According to the double-structure annular sintered body 100 shown in the lower part of FIG. 2 and exemplified in the specification, when the standard dimensions of the finished product are 105 mm in outer diameter, 90 mm in inner diameter and 60 mm in length, 3b, the outer diameter r0 'of the initial formed body 110a of the first cylindrical formed body is 106 mm (see FIG. 2) when the initial formed body 110a to be formed with the outer peripheral portion is primarily formed, And the inner diameter r1 of the cylindrical shaped body 120 is 96 mm. The molded body length Lout is formed to be 110 mm. Further, the second cylindrical shaped body 120 as the second metal powder is further formed The initial formed body 110a of the first cylindrical formed body which is firstly formed in the outer annular die of the second forming die 107 (see reference numeral 310 in FIG. 4A) is pressed together with the second metal powder Secondly, The first cylindrical formed body 110 to be secondarily molded is expanded and changed to 107 mm so that the outer diameter r0 thereof corresponds to the inner diameter R0 of the outer annular die 310 of the second molding die 300, The total length Lf of the cylindrical composite formed body 100 of the first cylindrical shaped body 110 and the second cylindrical shaped body 120 is reduced to 62 mm. On the other hand, the outer diameter r1 of the second cylindrical formed body 120, which is press-formed in contact with the inner peripheral surface of the first formed body 110a of the first cylindrical formed body, The inner diameter r2 of the first cylindrical formed body 110 is equal to the inner diameter of the first cylindrical formed body 110 and the inner diameter r2 of the first cylindrical formed body 110 is set to 86 mm which corresponds to the outer diameter of the relative sliding member So that it is molded into 88 mm.

Wherein the first metal powder comprises 0.3 wt.% To 1.3 wt.% Of graphite, based on the weight ratio; 0.1% by weight to 3.0% by weight of a bonding agent as at least one bonding agent selected from the group consisting of copper, nickel, manganese, and molybdenum nitride, and iron to the remaining known portion, The powder comprises 15% to 30% by weight of copper or copper alloy based on the weight ratio; 0.3% to 1.3% by weight of graphite; And it is preferable that iron is contained in the base portion. Furthermore, when a copper alloy is selected, the copper alloy may be any one selected from a bronze alloy (Cu-Sn) or a brass alloy (Cu-Zn).

The second cylindrical sintered body 110 and the first cylindrical sintered body of the outer circumferential portion of the first cylindrical formed body 110 may be formed to have a dual structure of an annular sintered body having different structural characteristics such as internal porosity, Is preferably formed at a powder density of 6.5 to 7.5 g / cm 3, preferably 7.0 g / cm 3, and the biaxial formed body 120 on the inner side thereof is relatively lower than the powder density of the first cylindrical formed body It is preferable to form it at a powder density of 5.5 to 6.5 g / cm 3, preferably 6.3 / cm 3.

As described above, the powder density of the first cylindrical formed body 110 having a relatively high molding density is higher than that of the cylindrical composite formed body 100 and the outer peripheral portion of the annular sintered body 100 having a double structure which is the sintered body thereof, The powder density of the second cylindrical formed body 120 having a relatively low molding density is advantageous from the viewpoint of providing strength characteristics, durability and corrosion resistance, and the powder density of the cylindrical shaped composite body 100 and the annular sintered body 100, It is advantageous in terms of providing a relatively high internal porosity in the inner periphery of the honeycomb structural body and providing better lubrication characteristics.

Hereinafter, a method for manufacturing a dual structure annular sintered body according to the present invention will be described with reference to the flowcharts of FIGS. 3A to 6B and FIGS.

That is, as shown in the flowchart of FIG. 7, the method for manufacturing the cylindrical composite sintered oil-

A metal powder preparation step (S100) of preparing a second metal powder having a powder composition different from that of the first metal powder and the powder composition of the first metal powder;

A first cylindrical shaped body initial molding step for putting a first metal powder into a space portion between the outer annular die 210 of the first forming mold 200 and the inner central core 220 and pressurizing the first metal powder to reach a first powder density (S200);

The first cylindrical formed body 110 is inserted into the outer portion of the space between the outer annular die 310 and the inner central core 320 of the second forming mold 300 and the first cylindrical formed body 110 The second metal powder is injected into the space between the inner central cores 320 of the second forming mold 300 so as to form the second cylindrical formed body 120 and the second cylindrical shaped body 120 (S300) of forming a cylindrical composite molded body by press-molding so as to reach a relatively low second powder density; And

A cylindrical composite formed body including the first cylindrical formed body 110 and a second cylindrical formed body 120 which is press-formed at an inner surface of the first cylindrical formed body 110 at a relatively lower powder density than the first cylindrical formed body is sintered to form a double- 100) at the same time (S400).

Here again, the first metal powder comprises 0.3% to 1.3% by weight of graphite, based on the weight ratio; 0.1% by weight to 3.0% by weight of a bonding agent as at least one bonding agent selected from the group consisting of copper, nickel, manganese, and molybdenum nitride, and iron to the remaining known portion, The powder comprises 15% to 30% by weight of copper or copper alloy based on the weight ratio; 0.3% to 1.3% by weight of graphite; And it is preferable that iron is contained in the base portion. Furthermore, when a copper alloy is selected, the copper alloy may be any one selected from a bronze alloy (Cu-Sn) or a brass alloy (Cu-Zn).

It is preferable that the first powder density for the first cylindrical formed body 110 is set to a powder density of 6.5 to 7.5 g / cm 3, preferably 7.0 g / cm 3, The second powder density for the cylindrical shaped body 120 is preferably set to a powder density of 5.5 to 6.5 g / cm 3, preferably 6.3 / cm 3, which is relatively lower than the first powder density.

And, in the joint sintering concurrently performing step (S400), the sintering sintering temperature is 950 캜 to 1200 캜; The bonding sintering time is from 10 minutes to 50 minutes; The bonding sintering atmosphere may be a reducing atmosphere or a vacuum atmosphere.

Furthermore, the cylindrical sintered oil-less bearing for high-speed (high surface-pressure) low-speed use can be manufactured by using the double-structure annular sintered body produced by the above-described method. Specifically,

A step (S500) of plastic-working the double-structure annular sintered body 100 made as described above, if necessary;

(S600) of heat-treating the annular sintered body (100) having the double structure subjected to the plastic working;

(S700) impregnating the heat-treated annular sintered body (100) of the double structure with oil; And

(S800) cutting the annular sintered body (100) having the double structure containing the oil.

Here, the step (S500) of plastic-working the double-structure annular sintered body 100 may include a step of increasing the strength of the inner circumferential surface, forming a structure having dimples or grooves, Is a process performed when it is necessary to apply a necessary shape change to the inner and outer main composite conjugate through one or more processes selected from a pressing process, a rolling process, and a drawing process, It is an optional process.

In addition, the step of heat-treating may be performed by any one of high-frequency heat treatment, quenching, carburizing or nitriding heat treatment.

Further, in the step of impregnating the oil, the oil impregnation temperature may be 60 to 100 DEG C, and the oil impregnation atmosphere may be a vacuum atmosphere or an air atmosphere.

Meanwhile, a step S900 of forming a coating layer by coating a solid lubricant on the inner circumferential surface of the cylindrical composite sintered oil-less bearing 100 produced by cutting the double-sided annular sintered body 100 may be further performed.

Here, the first metal powder is charged into the space between the outer annular die 210 of the first forming mold 200 and the inner central core 220, and the first cylindrical formed body 200 is pressed and molded so as to reach the first powder density. The initial forming step S200 will be described in more detail on the basis of the exploded perspective view of Fig. 3a, the assembled state sectional view of Fig. 3b and the operating state sectional view continuously shown in Figs. 4a and 4b.

As described above, the first cylindrical sintered body 110 forming the outer periphery of the annular sintered body 100 having a dual structure and the cylindrical composite sintered oil-less bearing 100 made using the same has graphite, that is, an iron- Powder is sintered at a higher powder density and has a higher rigidity than the second cylindrical sintered body 120 of the inner periphery, thereby supporting a load applied to the second cylindrical sintered body 120.

Here, the load applied to the second cylindrical sintered body 120 may be a load of the industrial machine itself to which the sliding type oilless sintered bearing of the present invention is attached, or an impact load generated when the industrial machine is operated, The first cylindrical sintered body 110 supports the second cylindrical sintered body 120 from the outside and improves strength and impact characteristics.

As shown in the exploded perspective view of FIG. 3A and the assembled state sectional view of FIG. 3B, in order to mold the first cylindrical formed body constituting the double-structure annular sintered body 100 according to the embodiment of the present invention, The first forming die 200 includes a first outer annular die 210 and a first outer annular die 210 spaced a predetermined distance from the first outer annular die 210. The first outer annular die 210 has a first center A first lower punch 230 provided to support and press the first metal powder into the annular space between the first outer annular die 210 and the first central core 220, And a first upper punch (240).

In order to form the first cylindrical formed body 110a with the first metal powder including graphite, the first outer annular die 210 constituting the first forming mold 200 and the annular annular shape The first metal powder Pw1 is press-molded between the first lower punch 230 and the first upper punch 240, which are inserted into the annular space portion by putting the first metal powder into the space. In the case of using the apparatus, the first upper punch 240 is downwardly pressed and press-molded.

The first upper punch 240 is lifted upward and then the first outer annular die 210 and the first center core 220 are moved downward so that the first upper punch 240 is moved upward The first cylindrical formed body 110a can be taken out to the outside, and this operation is clearly shown in Figs. 4A and 4B.

As described above, the first cylindrical formed body 110a separated from the first forming mold 200 by the first pressing molding is separated from the first cylindrical molding body 200 by the first pressing mold The first cylindrical molding body 110a is inserted into the second outer molding die 310 of the second molding die 300 and the second cylindrical molding die 300 of the second molding die 300 is inserted into the second molding die 300 shown in FIG. 2 inner center cores 320, as shown in FIG.

6A, the second cylindrical formed body 120 is inserted into the space between the first formed body 110a of the first cylindrical formed body and the second inner center core 320 of the second formed mold 300, The second metal powder Pw2 is injected so as to form the second cylindrical body 120 and the second upper punch 340 is lowered toward the second lower punch 330 as shown in FIG. (For example, a powder density of 6.3 g / cm 3) that is relatively lower than the first powder density (for example, 7.0 g / cm 3) of the first cylindrical formed body 110 to be pressure-pressed together with the second powder density . In this secondary press forming process, the diameter of the initial formed body 110a of the first cylindrical formed body is increased (from 106 mm to 107 mm in the illustrated embodiment) and its length is shortened (in the illustrated embodiment, from 110 mm to 62 mm The first cylindrical formed body 110 is subjected to the secondary press forming.

When the second upper punch 340 is moved upward again and then the second outer annular die 310 and the first center core 320 are assembled together, The cylindrical formed body 100 of the first cylindrical formed body 110 and the second cylindrical formed body 120 located on the second lower punch 330 can be taken out to the outside of the second forming mold 300 while moving downward This operation process is clearly shown in Figs. 6A and 6B.

Then, in the next joint sintering step (S400), the second cylindrical sintered body 120 is sintered and bonded together with the first cylindrical sintered body 110 at the outer peripheral portion thereof, and the inner pores formed by the sintering, Oil is impregnated into the inner pores of the two cylindrical sintered body 120, and when it is completed with the cylindrical composite sintered oilless bearing 100, surface contact is made with a relative sliding member (not shown) which requires sliding. In particular, when oil is impregnated into the abundant internal pores formed in the second cylindrical sintered body 120 by sintering the second cylindrical formed body 120, an oilless sintered bearing can be realized, It is possible to prevent a decrease in the operating rate of the industrial machine. In addition, since the base iron (Fe) is cured together with graphite during heat treatment to change into martensite structure, wear resistance of the second cylindrical sintered body 120 can also be improved. In addition, even if a separate lead (Pb) is not used, lubrication characteristics can be improved through sintering and oil impregnation, so that it can be eco-friendly.

Hereinafter, the components of the second cylindrical sintered body 120 composed of the second metal powder to be the iron-copper alloy powder will be described in detail.

The second cylindrical sintered body 120 forming the sliding layer of the iron-copper based alloy may contain 15 to 30% by weight of copper (Cu) or a copper alloy and 0.3 to 1.0% by weight % Graphite (Gr), and iron (Fe) in the base portion. In addition, the second cylindrical sintered body 120 may further include 0.1 to 3.0% by weight of other components, and the other component may be either one selected from nickel (Ni) or silver (Ag) It can be all kinds.

More specifically, the second cylindrical sintered body 120 of the second metal powder is manufactured by adding copper or a copper alloy having good toughness and sintering ability to an iron matrix (serving as a supporting portion to secure the strength of the sliding layer) It is possible to improve the friction characteristics with the relative sliding member (not shown) by adding only pure copper (Cu), which is mainly copper, or by adding a bronze alloy (Cu-Sn) or a brass alloy The sintering ability of the second cylindrical sintered body 120 provided as a pore wetting layer can be improved and the strength can be improved. For example, a copper-tin-bonded bronze alloy (Cu-Sn) has a low sintering temperature and therefore can be sintered under low temperature conditions (i.e., sintering of an iron-copper alloy powder) It is preferable to add a brass alloy (Cu-Zn) when a higher strength is required in the second cylindrical sintered body 120 portion. As another example, when high-temperature heat treatment is performed, pure copper (Cu) is added to iron medixes to prevent melting from occurring at a heat treatment temperature (approximately 910 ° C to 940 ° C).

When graphite (Gr) is added to the iron matrix of the second cylindrical sintered body (120), the graphite remaining in the second cylindrical sintered body (120) contributes to hardening of the iron matrix while being diffused in the iron matrix during sintering, And serves as a solid lubricant that provides additional lubrication to the second cylindrical sintered body 120 separately from the oil impregnated in the second cylindrical sintered body 120.

Nickel (Ni) or silver (Ag) having excellent bonding properties may be selected as the above-mentioned other components in order to improve the bonding strength of the outer peripheral portion to the first cylindrical sintered body 110, and the iron matrix of the second cylindrical sintered body 120 ≪ / RTI >

According to the experimental results of the double-structure annular sintered body (100) manufactured according to the present invention, any one selected from copper (Cu) or copper alloy (Cu-Sn or Cu-Zn) By weight to 30% by weight. That is, copper (Cu) or a copper alloy has a lower melting point than iron (Fe), has excellent lubricity and has a large diffusion coefficient and is easy to diffuse. When the addition amount is less than 15 wt%, the first cylindrical sintered body 110 , The lubricity and impact resistance of the second cylindrical sintered body 120 are lowered. If the addition amount is more than 30% by weight, the bonding strength and lubricity with the first cylindrical sintered body 110 are effective. On the other hand, Thereby excessively reducing durability. Therefore, according to the experimental results, it is possible to improve the strength and durability of the second cylindrical sintered body 120 and to improve the bonding property with the first cylindrical sintered body 110 by using a copper (Cu) The addition amount is from 15% by weight to 30% by weight.

Further, according to the above experimental results, graphite (Gr) was found to be most preferably composed of 0.3% by weight to 1.0% by weight based on the total composition. That is, graphite (Gr) is partially diffused into the iron (Fe) powder at the time of high temperature bonding to harden the iron powder, and a part thereof remains to serve as a solid lubricant. When the addition amount is less than 0.3 wt% ) Powder. If the addition amount is more than 1.0% by weight, the strength of the second cylindrical sintered body 120 serving as a sliding layer is lowered. Accordingly, it is necessary to add graphite (Gr) of an optimum amount to improve the strength of the second cylindrical sintered body 120, which can cure the iron (Fe) powder while also acting as a sliding layer. Therefore, according to the experimental results, the addition amount of the graphite (Gr) that can harden the iron (Fe) powder and improve the strength of the second cylindrical sintered body 120 was 0.3 wt% to 1.0 wt%.

According to the experimental results, when the other components such as nickel (Ni) or silver (Ag) are further added to the second cylindrical sintered body 120 in an amount of 0.1 wt% to 3 wt% The bonding strength between the sintered body 120 and the first cylindrical sintered body 110 is improved. Specifically, when the addition amount of the other components is more than 3% by weight, the amount of the liquid phase in the sliding layer (the layer formed by sintering the second metal powder) is high and the amount of deformation is large, Is less than 0.1% by weight, the amount of the liquid phase present in the sliding layer is too small to improve the bonding strength between the sliding layer and the first cylindrical sintered body 110 supporting the sliding layer, and does not contribute to the improvement of the strength of the sliding layer .

In order that the cylindrical composite formed body 100 is sintered as the cylindrical composite sintered body 100 in the simultaneous sintering step S400 so as to be a single bonded body with the double structure of the annular sintered body 100, Sintered joint. Particularly, to maintain the reducing atmosphere or the vacuum atmosphere at the time of sintering bonding, the oxide layer capable of being formed on the surfaces of the first cylindrical formed body 110 and the second cylindrical shaped body 120 is reduced to activate the bonding and sintering well . In addition, the second metal powder constituting the second cylindrical formed body 120 is diffusion bonded to the inside surface of the first cylindrical sintered body 110 while being sintered to become a sliding layer. The bonding sintering temperature for the above bonding and sintering in a vacuum atmosphere or a reducing atmosphere is 950 ° C to 1200 ° C which is the liquid phase appearance temperature of the copper (or copper alloy) powder serving as a bonding material, and the above bonding and sintering are performed The bonding sintering time required for forming the first cylindrical formed body 110 and the second cylindrical shaped body 120 varies depending on the thickness of the first cylindrical formed body 110 and the second cylindrical shaped body 120, but takes approximately 10 minutes to 50 minutes.

Then, in order to complete the cylindrical sintered oilless bearing 100 using the double-structure annular sintered body 100, the strength of the second cylindrical sintered body 120 may be optionally increased or, if necessary, A plastic working step (S500) may be performed to form the structure.

Further, in order to simultaneously harden the first cylindrical sintered body 110 and the second cylindrical sintered body 120 to improve strength and wear resistance, the double-structure annular sintered body 100 is heat-treated (S600). The heat treatment method includes high frequency, carburizing, quenching and nitriding heat treatment, and the optimum heat treatment method is selected according to the purpose and function and heat treatment is performed. Particularly, after the heat treatment, the iron particles are hardened to form a Martensite structure, which improves strength and abrasion resistance.

When the heat treatment is completed, the internal pores are impregnated with oil from the inner surface of the double-sided annular sintered body 100 according to the present invention (S700). For example, when the double-sided annular sintered body 100 according to the present invention is used at a high surface pressure (high load) low speed, the oil contained in the inner pores of the second cylindrical sintered body 120 is a gear oil having a viscosity of 220 cst or more It would be desirable to employ considerable oil. Further, the oil is impregnated in a vacuum atmosphere or an atmospheric environment, and the oil impregnation temperature required at this time is preferably set to 60 ° C to 100 ° C so that the oil can flow smoothly. Particularly, when oil is impregnated in a vacuum atmosphere, the oil can be impregnated smoothly into the inner pores by the vacuum force.

Thereafter, in order to attach the double-sided annular sintered body 100 composed of the first cylindrical sintered body 110 and the second cylindrical sintered body 120 to the sliding portion (not shown) of the industrial machine, the sliding portion Etc.) (S800). Such a cutting process may be a milling, a lathe, or a polishing method depending on the application.

Meanwhile, as described above, the step S900 of forming a coating layer by coating a solid lubricant on the inner peripheral surface of the cylindrical composite sintered oil-less bearing 100 formed by cutting the annular sintered body 100 having the double structure is further performed You may.

Among the components used in this specification, the name of the component is' 110a 'for' initial formed body 'in relation to' first cylindrical formed body ', and' The code '110' was used. On the other hand, in consideration of a situation in which the constituent elements corresponding to the reference numeral '100' are difficult to be shown in the figure due to the shape difference which changes according to the manufacturing steps, the 'first cylindrical formed body 110 and the second cylindrical shaped body 120' The name of its constituent elements, such as the cylindrical composite formed body 100, the cylindrical composite sintered body 100, the double-sided annular sintered body 100, and the cylindrical composite sintered oilless bearing 100, And the same reference numeral 100 is commonly used.

100: Cylindrical composite formed body, cylindrical composite sintered body, double structure annular sintered body, cylindrical composite sintered oilless bearing
110a: an initial formed body of the first cylindrical formed body
110: first cylindrical formed body
120: second cylindrical formed body
200: first forming mold
300: second forming mold

Claims (8)

delete An annular sintered body of a dissimilar metal with different metal powder composition in inner and outer circumference,
The first cylindrical shaped body formed of the first metal powder is first pressed with the initial formed body 110a and the inner cylindrical body is pressed with the second cylindrical shaped body 120 as the second metal powder, The first cylindrical sintered body 110 and the second cylindrical sintered body 120 are sintered and bonded to form the annular sintered body 100 having a double structure, 110); And
A second cylindrical shaped body 120 having a powder composition different from that of the first metal powder is formed on the inner surface of the first formed body 110a of the first cylindrical shaped body 110 forming the first cylindrical sintered body 110 The first cylindrical sintered body 110 is sintered at the same time as the first cylindrical sintered body 110 so as to form an inner peripheral portion of a dual structure annular sintered body 100 that is in contact with a relative sliding member requiring molding and sliding, And a second cylindrical sintered body 120 which is diffusion-bonded to the second cylindrical sintered body 120,
Wherein the first metal powder comprises 0.3 wt.% To 1.3 wt.% Of graphite based on the weight ratio; 0.1% by weight to 3.0% by weight of a bonding agent as at least one bonding agent selected from the group consisting of copper, nickel, manganese and molybdenum nitride, and iron as the remaining base portion,
Wherein the second metal powder comprises 15 wt% to 30 wt% of copper or copper alloy based on the weight ratio; 0.3% to 1.3% by weight of graphite; And the iron is contained in the base portion of the annular sintered body. The method as claimed in claim 2, wherein the first cylindrical formed body (110) is formed at a powder density of 6.5 to 7.5 g / cm 3, and the two cylindrical formed body (120) Wherein the sintered body is formed at a powder density of 5.5 to 6.5 g / cm 3, which is relatively lower than the density. delete A method for producing an annular sintered body having a dual structure,
A metal powder preparation step (S100) of preparing a second metal powder having a powder composition different from that of the first metal powder and the powder composition of the first metal powder;
A first cylindrical formed body initial forming step (S200) for forming an initial formed body of the first cylindrical formed body by charging the first metal powder into a space between the outer annular die of the first forming mold and the inner central core and press forming the same;
The first cylindrical formed body is inserted into the outer portion of the space between the outer annular die and the inner central core of the second molding die and the inner cylindrical core of the first cylindrical formed body The second metal powder is injected and pressurized so as to form a second cylindrical formed body in the space portion to form a cylindrical formed body of the first cylindrical formed body and the second cylindrical shaped body, wherein the first cylindrical shaped body reaches the first powder density, (S300) for forming the second cylindrical formed body on the inner side thereof by pressure molding so as to reach a second powder density relatively lower than a first powder density of the first cylindrical shaped body; And
A first cylindrical formed body and a second cylindrical formed body which is press-formed at a relatively lower powder density than the first cylindrical formed body on an inner surface of the first cylindrical formed body, and sintering the cylindrical formed body to join the annular sintered body having a dual structure (Step S400), and
Wherein the first metal powder comprises 0.3 wt.% To 1.3 wt.% Of graphite based on the weight ratio; 0.1% by weight to 3.0% by weight of a bonding agent as at least one bonding agent selected from the group consisting of copper, nickel, manganese and molybdenum nitride, and iron as the remaining base portion,
Wherein the second metal powder comprises 15 wt% to 30 wt% of copper or copper alloy based on the weight ratio; 0.3% to 1.3% by weight of graphite; And the iron is contained in the base portion of the annular sintered body. 6. The method according to claim 5, wherein the first powder density for the first cylindrical formed body is set to a powder density of 6.5 to 7.5 g / cm < 3 >, and the second powder density for the second cylindrical shaped body Wherein the powder density is set to a powder density of 5.5 to 6.5 g / cm 3, which is relatively lower than the first powder density. [7] The method as claimed in claim 6, wherein the first cylindrical shaped body is powder-formed only in the first cylindrical shaped body initial forming step (S200), wherein the initial formed body of the first cylindrical shaped body is formed at a powder density of 4.0 to 5.0 g / A method for producing an annular sintered body having a dual structure. The method according to any one of claims 5 to 7, wherein the bonding sintering temperature in the bonding sintering concurrently performing step (S400) is 950 to 1200 占 폚, the bonding sintering time is 10 to 50 minutes, Wherein the atmosphere is a reducing atmosphere or a vacuum atmosphere.

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