KR20020073647A - Wear-resistant sliding bearing for heavy load - Google Patents

Abstract

PURPOSE: An abrasion resistant sliding bearing is provided to achieve improved load-carrying capacity by improving lubrication, abrasion resistance and surface fatigue resistance of an inner sintered bearing layer of bearing. CONSTITUTION: A sliding bearing comprises a steel-back metal; a sintered metal layer(5) bonded to the steel-back metal, and which consists of 10 to 30 weight percent of copper, 0.1 to 5.0 weight percent of nickel, 0.1 to 8.0 weight percent of chrome and remainder of iron; and a dry lubrication agent contained in the sintered metal layer. The dry lubrication agent is one of 0.1 to 6.5 weight percent of graphite or 0.1 to 7.0 weight percent of molybdenum disulfide. The sintered metal layer has a ring type groove(9) which is formed by cutting away a portion of the sintered metal layer so as to store grease in the ring type groove.

Description

Wear-resistant sliding bearing for heavy loads {Wear-resistant sliding bearing for heavy load}

The present invention relates to an improvement of the applicant's Korean Patent No. 286246 (US Pat. No. 6,086,257). The present invention is a composition in which a predetermined amount of chromium (Cr) is further added to the small-bonded gold layer composition of the sliding bearings disclosed in Korean Patent No. 286246, and a predetermined amount of molybdenum (Mo) and phosphorus (P) is additionally added or simultaneously added. To manufacture sliding bearings and to provide sliding bearings having a non-paying period of 500 to 1000 hours or more under severe high surface pressure (high load) of 700-1000 kg / cm ² , mainly for pin bushing and injection machines of heavy equipment such as excavators. Toggle pin bushings and joint bushings and corresponding sliding bearings with remarkable low friction lubrication, abrasion resistance and impact resistance, and surface fatigue resistance, even under prolonged unloading under high surface pressure (high load) and impact load.

Applicant disclosed in Korean Patent No. 286246 to form a small alloy layer by sintering and joining an iron-based metal mixed powder molded body to a steel-backed metal at the same time, thereby forming a load-carrying capacity, fatigue strength and indentation. Sliding bearings and a method of manufacturing the same have been proposed to improve the properties, and the present invention, while taking advantage of these structural advantages, derives alloying and complexation of the small-bonded alloy layer by further additional elements, low-density iron-based alloy layer It is to provide a sliding bearing which has remarkably low friction lubrication, wear resistance and impact resistance and surface fatigue resistance even in a long unpaid period under severe high surface pressure.

On the other hand, in addition to the applicant's Korean Patent No. 286246, conventional double-sided sliding bearings composed of a metal back side metal and a small alloy layer include copper, copper-tin (Japanese Patent Laid-Open Publication No. 4-202637), copper-zinc- Lead (Japanese Patent Publication No. 5-36486), Aluminum Bronze (Japanese Patent Publication No. 5-156388), Aluminum (Korean Patent Publication No. 96-3902), Linkage (Japanese Patent Publication No. 6-287796 ) And synthetic resins (Korean Patent Publication No. 92-8640, Japanese Patent Publication No. 5-35184). They are not suitable for long-term unloading under heavy loads of 300-500 kg / cm ² or higher because of the relatively low strength and hardness of the small-bonded alloy layer in contact with the sliding mating element (shaft or pin). Since the hardness and strength cannot be increased by the heat treatment and structure-controll method as described above, the bearing field according to the present invention is different from the bearing according to the present invention, which is developed as a low load and high load application due to its low wear resistance and load resistance.

Conventional techniques for adhering an iron-based alloying layer to a metal on a steel back side include Japanese Patent Application Laid-Open No. 56-108804 (US Pat. No. 4,959,274). In the case of a bearing in which a (Fe-Pb-Cu) sintered alloy layer is joined by the double rolling adhesive method, the maximum allowable load that can be used without occurrence of sintering under the condition that lubrication oil is continuously supplied starts to be 250 kg / cm ² or less. Doing.

In addition, currently used high-load steel bushes, namely, carburized heat-treated steel bushes and high-frequency heat-treated steel bushes, have a non-payment period even if they are coated with a molybdenum disulfide coating layer on their inner surface or subjected to phosphate coating. It does not exceed -50 hours, and when it is operated with no paper, the friction joint, sintering, wear, etc. are extremely remarkable and can not be used, and even the sliding element such as shaft or pin It causes serious damage to peripheral parts. Therefore, in the case of steel bush, it can have a load resistance only in a continuous feeding state, and in general, since it is hardened by heat treatment, its shock absorbing ability is insufficient.

In addition, brass bushings have a lower load resistance at high loads, abrasion resistance is significantly weaker than iron-based bushes, and impurities, foreign matters, and debris in wet lubricants, even when continuous feeding at high loads or special treatment of peripheral parts. The surface fatigue caused by fritting and cavitation caused by) cannot be prevented. Here, surface fatigue refers to fritting corrosion caused by debris of impurities, foreign matter and its own material in the wet lubricant, thereby creating deep pits perpendicular to the friction surface. These pits create cracks in the lower layer of the friction surface in a direction parallel to the friction surface by cavitation, while the cracks are connected to each other by the load applied to the bearings and the surface is torn off visually. Abrasion that occurs in the form of a plate. Surface destruction caused by this type of wear is characterized by slow and violent behavior.

On the other hand, as another example, there is also an example of a small alloy bearing consisting only of iron-based copper alloy composed of iron, copper, carbon (compound carbon, that is, solid carbon) without metal if the steel for high load, unpaid (US Pat. No. 5,518,030). ). However, these sliding bearings are made of iron-based alloying alloys without steel, so that the load carrying capacity (surface pressure) can be better than that of non-ferrous alloy bearings, but the dry (solid) lubricants (molybdenum disulfide and / or free carbon) in the molded body When containing a large amount of the molding and sintering is difficult because there is a manufacturing limitation. In addition, in the case of steel, in the case of manufacturing a bearing using only iron-based alloys without metal, the diameter and length of the bearing are limited to a small size when the solid lubricant is included. In other words, when a large amount of the dry lubricant is contained by increasing the diameter and length, the molding and sintering itself becomes crumbly, which makes it practically impossible to manufacture for a desired use. Therefore, this technique is generally not able to include a dry lubricant to maintain the rigidity of the small-bonded gold bearing, it is limited to a very small amount even if included, and even if it contains a solid lubricant to form and sinter it, the sintered body lacks the rigidity of the considerable use Constraints (indentation into the housing, impact resistance, machining, handling, etc.). Therefore, if steel is used, only iron-based copper alloy bearings composed of iron, copper, compound carbon, that is, solid carbon, without metal, the main lubrication mechanism is to use mainly wet lubricant (lubricating oil). At high loads and low speeds, there are problems such as instability of friction coefficient, overheating due to frictional heat accumulation, fragility to impact, impact, release and loss of back oil.

On the other hand, in view of the above problems, in the above-mentioned Korean Patent No. 286246 of the present applicant, the iron-based alloy layer is joined to the steel back metal simultaneously with sintering to allow the surface pressure of 300-500 kg / cm ² or more (maximum 700 kg / cm ² ) has been proposed to improve the sliding bearing, and to provide a non-feeding period of 300-1000 hours. The sliding bearings proposed as satisfying these conditions in this patent should be made of iron alloy layer whose main component is iron which can be heat treated (iron type), and if the metal alloy layer and steel are made of metal, the structure is integrally bonded. (Integrated multilayer structure), copper, which is an essential element of sintered alloy, must be included in the sintered alloy layer in an appropriate amount (10wt% -30wt%). The patent should also have a porosity of preferably 30 volume% or less so that the small-bonded layer can contain an appropriate amount of a wet lubricant (lubricating oil or grease) while maintaining its strength, and furthermore, the metal upon sintering Dry lubricants that can be included without compromising the adhesion between the powder mixture particles are presented as graphite 6.5 wt% or less and / or molybdenum disulfide 7.0 wt% or less.

However, it is an object of the present invention to provide a bearing that can be used under conditions in which the permissible load (permissible surface pressure) is 700-1000 kg / cm ² or more severely added, and furthermore, the non-payment period is maintained under such a high load. The sintered alloy bearing itself is extended to at least 500 to 1000 hours. Accordingly, the present invention is to provide a sliding bearing that significantly improves the low friction lubrication, wear resistance and impact resistance, surface fatigue resistance of the low-bonding gold bearing layer under high load and long paper-free conditions.

In order to achieve the above object, the present invention preserves the structural advantages of the double layer bearing formed by joining an iron-based alloy layer to a steel back metal, which is disclosed in Korean Patent No. 286246 of the present applicant, while the porosity of the iron-based alloy layer is maintained. In addition to the characteristics of providing a dry lubricant and a wet lubricant, the base structure is alloyed and compounded by additional addition of alloying elements to the iron-based alloy bearing layer. In the present invention, in order to achieve durability such as low friction coefficient and abrasion resistance through alloying and compounding of the matrix structure, it is an essential premise that the alloying and complexed small alloy layer and the metal should be soundly bonded together. There is a condition. That is, whenever a specific metal powder is added for alloying and complexing of the matrix structure, the iron-based mixed powder causes dimensional change during sintering, and in many cases, it is bonded to the metal by the shrinkage phenomenon caused by densification. If the steel is expanded at the sintering temperature, the metal expands, so if the iron alloy sintered body and the steel are not joined, the metal is separated or there is a large amount of gap. The problem must be solved.

The present invention has been devised as a result of the addition of various kinds of alloying elements in view of the above-described conventional problems, and the bearing itself under high surface pressure (high load) of 700-1000 kg / cm ² , and low speed for a long time of 500 to 1000 hours or more. It has a paper-free period, and with the presence (reinforcement) of existing steel, it is not only load-resistant, fatigue strength and indentation, prevention of departure and loss of back oil, but also stable low friction of low density iron-based alloy layer, which is a bearing material. An object of the present invention is to provide a sliding bearing with improved lubrication, wear resistance, impact resistance, and surface fatigue resistance.

1 is a view showing a process of pressing the iron-based alloy in a steel back metal in the manufacture of a bush-type sliding bearing according to the present invention.

2 is a perspective view showing an embodiment of a bush-type sliding bearing according to the present invention.

3 is a cross-sectional view showing a sliding bearing made to have a long length by joining the bush-type sliding bearing of Figure 2 having the same inner and outer diameters in the longitudinal direction.

FIG. 4 is a cross-sectional view showing another embodiment of a sliding bearing having an annular groove 9 in which a small alloy layer is annularly removed on the inner circumferential surface of the sliding bearing for the purpose of functioning as a grease feeding and storage groove.

FIG. 5 is a cross-sectional view illustrating a sliding bearing of another embodiment configured to have a longer length by joining the bush-type sliding bearings of FIG. 2 having the same inner and outer diameters in a lengthwise direction.

6 is a perspective view showing an embodiment of a plate-type sliding bearing according to the present invention.

<Explanation of symbols for the main parts of the drawings>

1, 2, 3: sliding bearing 4: steel back side metal

5: small bond layer 6: water coupling jaw

7: female coupling jaw 9: annular groove

10: second oil supply hole 11: the first oil supply hole

12: sliding element 13: housing

14: nipple 15: dust seal

In order to achieve the above object, the sliding bearing according to the present invention is a steel back metal; If the steel is bonded to a metal, 10-30 wt% copper, 0.1-5.0 wt% nickel, 0.1-8.0 wt% chromium, the remainder comprises an iron-based alloy layer consisting of iron, preferably in this iron-based alloy layer Dry lubricants include 0.1-6.5 wt% graphite and / or 0.1-7.0 wt% molybdenum disulfide. In addition, the iron-based alloying layer of the sliding bearing of the present invention more preferably comprises at least one of molybdenum 0.1 to 5.0 wt%, phosphorus 0.01-3.0 wt%.

According to the present invention, if the steel is sintered simultaneously with the metal, copper 10wt% to 30wt%, nickel 0.1wt% to 5.0wt%, chromium 0.1wt% to 8.0wt%, the remainder is made of iron and graphite as a dry lubricant The bush-type method of manufacturing a sliding bearing composed of a low density iron-based alloy layer having a porosity of 10% to 30% containing 0.1wt% to 6.5wt% and / or 0.1wt% to 7.0wt% molybdenum disulfide is basically in Korea. It is the same as the shaping | molding method and the sintering method which were shown by patent 286246.

In other words, the metal mixing powder having the composition ratio as described above is evenly mixed, as shown in Figure 1 of the molding apparatus 50 is provided with a core 20 is installed in the center and the lower pressure member 30 at the bottom Inserting the steel if the metal (4) in the mold 60, and then filling the mixed metal mixed powder (5) between the steel if the metal (4) and the core 20, the upper pressing member at the upper end of the mold (60) Insert (70) to pressurize. Subsequently, the molded body 5 in which the metal mixed powder 5 is press-molded is taken out together with the metal 5 if it is steel. In the pressing, the upper pressing member 70 or the lower pressing member 30 may be selectively pressurized or all pressurized. Molding pressure is preferably maintained at a pressure of 50 ~ 300kg / ㎠, but the size of the pressure is variable in consideration of the desired porosity (volume ratio of the pore to the volume of the entire small alloy layer) after sintering joining The porosity range is preferably set to 10 to 30%.

Next, the molded body 5 is sintered together with the steel backing metal 4 at a sintering temperature of 1035 ° C to 1095 ° C for 3 to 25 minutes, and then cooled to 750-950 ° C in a furnace and held at this temperature for 30 minutes or less. Immediately afterwards, the small alloy layer 5 sintered to the metal 4 is deposited in a quenching medium. On the other hand, the small-bonded gold layer 5 after sintering for 3 to 25 minutes at 1035 ° C to 1095 ° C may be cooled to 750-950 ° C and then rapidly cooled at this temperature without holding time. The sintering bonding process is carried out in any one gas atmosphere selected from the group comprising nitrogen, hydrogen, or a mixed gas atmosphere of nitrogen and hydrogen, ammonia decomposition gas atmosphere, argon gas atmosphere, vacuum pressure or endo and exothermal gas atmosphere. In the mixed gas atmosphere of nitrogen and hydrogen, hydrogen is preferably contained in a volume ratio of 30% or more with respect to the mixed gas, and in the case of vacuum pressure, 10 ^-2 torr or less is preferable. By this manufacturing process, as shown in FIG. 2, a bush-type bearing having a multilayer structure in which the metal 4 and the small-alloy layer 5 are integrally bonded is manufactured.

On the other hand, the molded article of the composition is sintered to a predetermined shape, such as a hollow pipe shape without steel if the metal first (sintered at 900-1250 ℃, which is the general sintering temperature range of the iron-based molded article), and then the post-bonding process If the steel pipe of the hollow pipe shape through the metal inner circumferential surface can be manufactured by sliding bearings having a two-layer structure, but this method is not only in terms of energy efficiency (manufacturing cost) but also the production process due to the complicated process number It is not preferable in terms of performance. In addition, if this method is steel, it is necessary to join the metal and the small-bonded alloy afterwards. Therefore, if the steel is required to precisely match the size of the inner diameter of the metal and the outer diameter of the sintered body, it may not be easy to match the degree of processing. Therefore, as long as the content of the composition of the small-bonded metal layer is the same and steel shares the technical idea of a multi-layered structure in which a metal and a sintered body are joined, not only simultaneous joining of the metal and the sintered body but also subsequent joining thereof are also considered in the technical spirit of the present invention. Although it is in the range, it is preferable to use a single step joining method in which the sintering and joining are performed simultaneously as described above.

The hardness and strength of the small-alloy layer 5 are further improved by performing heat treatment such as carburizing, nitriding, nitriding, nitriding, quenching, and soaking of the sliding bearing 1 obtained by sintering bonding or sintering by the above-described methods. This heat treatment is possible because the small-bonded metal layer 5 is made of iron as a main component. In the case of continuous sintering and heat treatment in the continuous furnace, sinter bonding or joining is carried out in the heating table, and the sliding bearings (1) are transferred to the cooling table, and then maintained at a temperature of 750 to 950 ° C. in the cooling table, followed by carburizing, nitriding and carburizing. Preference is given to performing nitriding, quenching and sourcing.

According to the present invention, as shown in Figure 3, by sliding and welding a plurality of metal in the longitudinal direction of the steel back surface sliding bearing having a long length can be made. That is, as a method of manufacturing a sliding bearing having a long length in the longitudinal direction, if one of the sliding bearings is steel, one end of the metal (4) has a female coupling jaw (6, 6), the other is steel On the outer circumferential surface of the back metal (4) to have a male coupling jaw (7, 7) to be engaged with the female coupling jaw, then they are combined with each other by sliding or bonding the surface of the coupling surface TIG welding (2) ) Can be prepared. The sliding bearing 2 according to the present invention thus formed is provided with an annular groove 9 on the inner circumferential surface of the small alloy layer 5 to function as a grease feeding and storage groove.

In addition, as shown in Figure 5, if the steel of the two sliding bearings at both ends of the metal (4) outer circumferential surface to have a male coupling jaw (7, 7), if the middle steel, the metal (4) both ends of the female coupling jaw ( 6, 6), and then combining the coupling jaws to fit each other in the shape of a male and female can be produced even longer sliding bearings by TIG welding or brazing. The sliding bearing 2 of the present invention is provided with two or more annular grooves 9 on the inner circumferential surface of the small alloy layer 5 to function as a grease feeding and storage groove. However, these annular grooves are not only formed by joining joining jaws at their ends to a plurality of steel face metals, but also in a subsequent position of joining a small bond layer over the entire length of the metal inner circumferential face. It may be formed by cutting off the sintered layer by a desired width W by processing.

Therefore, the produced sliding bearing is an annular groove in which the small-bonded alloy layer is removed from the inner circumferential surface of the sliding bearing 3 for the purpose of functioning as a grease feeding and lubricating oil storage groove as shown in Korean Patent No. 261896 and FIG. 4. 9) having a second oil supply hole 10 formed on the outer circumferential surface of the sliding bearing so as to be in communication with the groove, and made of a bearing having two or more first oil supply holes 11 so as to be further in communication with the second oil supply hole. It is preferable. In the bearing according to the present invention, the load-bearing, low-friction and wear-resistant characteristics of the bearing are basically formed by the composition and the multilayer structure contained in the sintered body, and the annular grooves 9 serving as a grease storage and feeding function are provided. The presence of the synergistic effect can be expected in the present invention by the presence, but the size of the width (W) does not significantly affect the technical concept of the present invention, the annular groove (9) in the present invention The width W may be arbitrary without any particular limitation.

The sliding bearing of the present invention can be made in various shapes according to the purpose of use, such as bush type and plate type as shown in Figure 6 as shown in Figures 2 to 4.

As described above, the porosity in the small-bonded metal layer 5 is preferably made up to 30% by volume by controlling the molding pressure in the molding step. Porosity can also be produced in a high density of about 5% or less by volume ratio by adjusting the molding pressure.

In addition, if the steel used in the present invention metal (4) is made of carbon steel, the copper plating treatment to a thickness of 2-10μm by electroless plating or electroplating before being integrally molded by the molding apparatus together with the iron-based mixed powder It is desirable to be. Here, stainless steel may be used as the metal if it is steel.

According to the present invention, the constituents of the small-bonded metal layer 5 are preferably 10-30 wt% copper, 0.1-5.0 wt% nickel, 0.1-8.0 wt% chromium, and the balance of iron. As a dry lubricant, 0.1-6.5 wt% of graphite and / or 0.1-7.0 wt% of molybdenum disulfide may be further added.

In addition, according to the present invention, the small-bonded alloy layer 5 may be added with molybdenum and phosphorus selectively or simultaneously in addition to copper, nickel, chromium, graphite, molybdenum disulfide and iron, in which case the component ratio is 0.1 to 5.0 molybdenum wt%, phosphorus may be 0.05-3.0 wt%.

Graphite or molybdenum disulfide contained in the inside of the small alloy layer 5 acts as a dry lubricant for satisfying long-term lubrication-free and paper-free conditions. In order to further increase their dry lubrication effect, it is preferable to fill (impregnate) a wet lubricant such as lubricating oil (or grease EP2) shown in Korean Patent No. 261896 in the pores of the small-bonded alloy layer. In addition, as the lubricating oil or grease used for this impregnation, a mixture of graphite and molybdenum disulfide having a particle size of 200 μm or less is preferably mixed in a weight ratio of 50% or less and suspended.

When showing the configuration and effect of the alloying elements constituting the sliding bearing according to the present invention.

The content of graphite and / or molybdenum disulfide can be limited to not more than 6.5 wt% and not more than 7.0 wt%, respectively. This is because the dry lubrication characteristics of low friction can be improved without being damaged. Some of the graphite is dissolved in iron (carbon or solid carbon), and another is iron-carbon compound (Fe ₃ C) and free graphite, which is uniformly present in the sintered layer. Contributes to characteristics (low friction coefficient). Molybdenum disulfide is uniformly dispersed in the sintered layer, and exhibits a low coefficient of friction that is stable in the long-term unpaid paper, because it retains extreme pressure and dry lubrication characteristics (low friction coefficient).

Copper (Cu) is an important element that plays a decisive role in the bonding and sintering of the metal and iron-based alloy layer if the steel, the beneficial content range for bonding is 10 wt% to 30 wt%. If it is out of this range, there will be separation or gap in the joint surface, and the joint will not work properly. Some of the copper (Fe) is combined with (Fe) iron (Fe) to precipitate in the form of fine particles in the matrix, and another is combined with phosphorus (P) to form a hard copper-phosphorous compound (Cu ₃ P) The remainder is free copper in a form independent of bonding. This free copper facilitates sintering and is distributed in a network structure (shape) in the sintered layer, thereby having the effect of hard iron base structure (martensite or fine pearlite) and alloying elements (solid solution and It absorbs external impact on hardened and hardened matrix structure due to the uniform distribution of hard precipitated compound particles.

Nickel (Ni) increases the hardenability by heat treatment, but when 5wt% or more is added, it causes a shrinkage of the sintered layer, which adversely affects the overall bondability because an unbonded gap can be formed between the small alloy layer and the steel. .

Chromium (Cr) combines with iron and carbon to form a light complex carbide, which distributes them uniformly and finely in the matrix structure, and easily diffuses into the base structure to improve the wear resistance of the matrix structure, but adds more than 8.0wt%. If it is steel, it is harmful to joining in the form of gap between metal and iron base alloy layer. The addition of chromium is preferred for abrasion resistance, corrosion resistance, and oxidation resistance of matrix tissue, but coarsening of crystal grains occurs when added at 5.0 wt% or more.

Molybdenum (Mo) combines with iron and carbon to improve the wear resistance of the matrix structure by uniformly depositing light and fine complex carbides, but when added more than 5.0wt%, the gap between the metal and the iron-based alloy layer It is harmful because it makes it.

The addition of phosphorus (P) is caused by uniform and fine deposition of iron-phosphorus compounds (Fe ₃ P), iron-carbon-phosphorus compounds (steadite) and copper-phosphorus compounds (Cu ₃ P) in the matrix structure Increasing the hardness of the base structure improves the wear resistance of the matrix, but when added more than 3.0wt% causes severe shrinkage of the sintered layer, if the steel is to cause a separation of the metal and iron-based alloy layer adversely affects the bonding.

Sliding bearings (1, 2, 3) of the composition as described above, first, the bearing layer (5) is an iron-based alloy layer of iron is the main component is combined with graphite to form a base structure of carbon steel, the carbon steel base structure of the alloy element By addition (quantity) and quenching, quenching and annealing, carburizing, nitriding, annealing and the like, the hardened martensite, fine pealite, that is, sorbite and soft tissue, ferrite ( ferrite), pearlite, and the like, and by maintaining the toughness and ductility by the ratio of each matrix structure, the hardness can be improved to add abrasion resistance. Second, by the addition effect of alloying elements, fine and uniform hard Of the complex compounds are precipitated inside and around the base structure to further enhance the micro and macro curing, thereby adding more wear resistance. Such abrasion resistance plays an important role in maintaining the low friction lubrication for a long period of time together with the dry lubricant of graphite and molybdenum disulfide contained in the small-bonding gold bearing layer 5 and the wet lubricant of the lubricating oil contained in the pores.

<Example 1-3>

The sliding bearing of the present invention was fabricated and subjected to abrasion abrasion test for more than 1000 hours at a sliding speed of 0.3 m per minute under a high load of 900 kg / cm ² . The sample has an inner diameter of 70 mm, an outer diameter of 85 mm, a length of 60 mm, and a shape of which is formed such that an annular groove having a width (W) of 10 mm is formed on the inner surface as shown in FIG. Durable equipment was given a vertical load of 50 tons hydraulic pressure and the compressive load was measured by a load cell. The shaft (S) (shaft) in the bush bore was allowed to oscillate at an angle of 100 degrees, and the torque required to rotate while overcoming the vertical load was measured by attaching a torque cell, and the coefficient of friction was converted therefrom. The temperature of the bush was measured by contacting the thermocouple on the outer peripheral surface of the bush. The bush was treated with a wet lubricant after drying, and the bearing was press-fitted into the housing 13 and subjected to one grease injection through the nipple 14 before testing. Roughness of the inner surface of the bush was polished to 12.5 S or less, and the roughness of the shaft to 0.8 S or less. The clearance between the bush and the shaft was kept below 0.10 mm. The performance test was performed by stopping the test once every 100 hours and restarting it as it was about 1 day later. The total amount of abrasion was expressed as the difference between the average value of the five measurements of the initial bushing diameter and the average value of the final inner diameter of the rocking surface after washing and drying the test sample.

From the results of Table 1, in the case of the sliding bearing of the present invention, the friction coefficient is 1000-hour without grease at a high load of 900 kg / cm ^{2, and} the friction coefficient is in the range of 0.04-0.12, and the total amount of wear is also in the range of 30-60 μm. As a result, the sliding bearing of the present invention exhibits a stable low friction coefficient and a low wear rate as desired.

Sampler Ho Density (g / cm ² ) Apparent Hardness (HRB) Coefficient of friction Total wear (μm) Relative Axis Total Wear (μm) Example 1 6.3 20-40 0.05-0.11 30-50 below 10 Example 2 5.7 50-70 0.04-0.10 30-40 below 10 Example 3 5.9 60-80 0.04-0.12 30-60 below 10

<Comparative Example 1-5>

The conventional bearings described above were subjected to a friction wear test under the same conditions as in Examples 1 to 3 through Comparative Examples. The test time was discontinued when the friction coefficient increased above 0.4. Comparative Examples 1 to 5 indicate that it cannot be used as a paper-free paper at a high load of 1000 kg / cm ² or more as summarized in Table 2, and when tested with paper-free paper, the coefficient of friction is 0.4 or more when the test time is about 1-5 hours. As a result, the wear test and the measurement of the total amount of wear could not be made due to excessive heat, scratches, sintering, and joints. In the case of these comparative examples, since the bearing itself does not contain a dry lubricant, there is no lubricating effect at high surface pressure by adding one grease at all.

Sample sign sample Hardness Coefficient of friction Total wear (μm) Total test time (hr) Comparative Example 1 STEEL HRC 50-60 0.4 or more Not measurable (scratch, overheat, sinter, joint) One Comparative Example 2 Brass A HRB 90-100 0.2-0.4 Not measurable (scratches, overheating, sintering, joints) 3 Comparative Example 3 Brass B HB 100 0.2-0.4 Not measurable (scratches, overheating, sintering, joints) One Comparative Example 4 Iron-based Sintering A HRB 70-90 0.2-0.4 Not measurable (scratches, overheating, sintering, joints) 5 Comparative Example 5 Iron-based Sintering B HB 30-50 0.2-0.4 Not measurable (scratches, overheating, sintering, joints) 3

The effect of the sliding bearing according to the present invention made as described above is as follows.

1) Steel-backed metal is carbon steel that can be adjusted in hardness by heat treatment, and the inner surface of bush (iron-based alloy bearing layer) can be controlled by hardness and alloyed with chromium, molybdenum and phosphorus. Hardening of the tissues and precipitation of finely dispersed complex compounds further improve wear resistance, and low friction lubrication is maintained by the included solid lubricants (graphite and / or molybdenum disulfide). Therefore, if the steel is a metal to support the load of the low-density bearing material, and the low friction lubrication and wear resistance of the inner sintered bearing layer is further provided, the allowable load is improved to 700-1000 kg / cm ² or more.

2) The non-bonded gold layer, which is further abrasion resistant by alloying and heat treatment, maintains abrasion and low friction lubrication (friction coefficient 0.04-0.12) by the combined magnetic lubrication effect of the embedded solid lubricant and wet lubricant. This greatly increases the grease feeding cycle to more than 1000 hours.

3) The small-bonded gold bearing layer has excellent shock absorption ability due to the glass copper distributed between the hard base structure, the composite compound, the pores, and the solid lubricant.

Claims (8)

Steel and metal; 10 to 30 wt% copper, 0.1 wt% to 5.0 wt% nickel, 0.1 wt% to 8.0 wt% chromium, and the other iron-based alloy bonding layer made of iron; And, It comprises a dry lubricant contained in the iron-based bond layer; The dry lubricant is a sliding bearing, characterized in that at least one of 0.1 wt% to 6.5 wt% graphite or 0.1 wt% to 7.0 wt% molybdenum disulfide. The method of claim 1; The iron-based bond layer is a sliding bearing, characterized in that further comprises at least one of molybdenum 0.1 wt% to 5.0 wt% or phosphorus 0.01 wt% to 3.0 wt%. The method of claim 1 or 2; The sliding bearing is characterized in that the carburizing, nitriding, carburizing nitriding, quenching, quenching and soaking and the like and heat treatment equivalent thereto. The method of claim 1 or 2; And the small bond layer has at least one annular groove having an annular shape in which the small bond layer is annularly removed to serve as a grease feeding or grease storage groove. The method of claim 4, wherein If the steel is metal, the ring-shaped jaw formed in both ends is connected to the plurality of longitudinal connection, the sliding bearing, characterized in that the annular groove of the small alloy layer is located on the inner peripheral surface of the junction The method of claim 1 or 2; The sliding bearing is a sliding bearing, characterized in that the iron-based alloy layer is bonded to a metal if the steel at the same time as the sintering in the temperature range 1035 ℃ -1095 ℃. The method of claim 1 or 2; The sliding bearing is a sliding bearing, characterized in that the iron-based alloy is first made of sintering first and then secondly bonded to the metal if the steel in the temperature range 1035 ℃ -1095 ℃. The method of claim 1, The sliding bearing, characterized in that the content of chromium contained in the iron-based bond layer is 0.1wt% to 5.0wt%.