KR20140104629A - Bush having double structure and bearing assembly having the same - Google Patents

Abstract

The present invention relates to a bush in a dual structure, the bush being used in a joint portion which operates in low-speed and high-load, and a bearing assembly including the same. The present invention is a bush formed of a polymer composite material, unlike a conventional metallic bush, and has excellent elasticity and recovery properties under a low-speed high-load operating condition so as to distribute a load uniformly because the bush is transformed when a local load is applied. Therefore, abnormal wear due to stress concentration and damage due to impact can be prevented so as to improve wear resistance and impact resistance and improve lifespan characteristics.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a bush having a double structure and a bearing assembly having the bush,

The present invention relates to a bush having a dual structure which can be used for a joint which operates under a low-speed high load, and a bearing assembly having the bush.

Construction machines such as excavators, skid steer loaders and the like include a plurality of joints such as joints of boom and arm, joints of arm and bucket, and the like. The joints of these construction machines are generally made of pins and bushes that oscillate in the lubrication environment of grease.

1 shows a front joint part 10 of an excavator as an example of a construction machine, and FIG. 2 is a cross-sectional view showing a conventional bush in the joint part 10 of the excavator in a direction perpendicular to the longitudinal direction of the pin. 2, the joint part 10 includes a pin 12 connecting two members requiring joint motion, a bush 11 for reducing frictional resistance occurring between the pin and the pin hole, . The pin 12 and the bush 11 generally oscillate in a lubrication environment with grease. In addition to the pins 12 and the bushes 11, the joints 10 may include bosses 13 of a housing for supporting the pins and the bushes and sealing means (not shown) for blocking contaminants .

These joints operate under various conditions depending on the type of connection of the pins and bushes, the working environment, and the joints, and generally operate under the conditions of a pressure of about 2 to 6 kg / mm ² and a speed of about 0.25 to 5 cm / sec do. These operating conditions are typical averages, and the surface pressure during operating conditions can rise instantaneously depending on the working load, and in particular, the instantaneous surface pressure can be more than three times the average value due to the offset load during operation depending on the operating conditions.

As described above, bushes used under low-speed high-pressure conditions are required to have excellent scuffing resistance and abrasion resistance, and various compositions and shapes have been developed and used for this purpose.

For example, a metal bush having grooves or dimples formed on an inner circumferential surface of a metal body to maximize lubrication performance by containing grease in the grooves or grooves; A metal bushing whose surface is coated with self-lubricating particles to maximize lubrication performance; And a porous sintered metal bush impregnated with a lubricant.

However, since the directions and numerical values of the loads applied to the respective parts are very unspecific and vary from time to time due to the topography, the working posture of the equipment, and the lipid, the front-end working machine of the construction machine causes bending of each part between the works, An overload occurs as a whole and a high load is concentrated in the local area. As a result, all parts, including bushes, require a high level of abrasion resistance and impact resistance.

However, in the case of the metal bushes known to date, there is a limit in the elastic strain regardless of the shape thereof. As described above, under the condition that the direction and numerical value of the load are unspecific and fluctuating, high load application in the local area can not be avoided. Also, even if the surface of the metal-based bush is coated with the self-lubricating particles, the service life of the self-lubricating particles is limited and it is difficult to continuously maintain the lubricating environment after the initial locating step of the bush surface. On the other hand, when the porous metal sintered body is continuously exposed to the impact, the pores in the sintered body are gradually reduced from the surface subjected to the load. In an extreme case, the pores in the sintered body are closed, and it may be difficult to continuously exhibit the lubricating effect by the lubricant impregnated in the sintered body.

It is an object of the present invention to provide a bush which is applied to a joint which operates under a low-speed high load, and which can exhibit excellent elasticity, recoverability, lubrication characteristics and load-bearing property.

Another object of the present invention is to provide a bearing assembly including the bush.

According to the present invention, there is provided a sliding device, comprising: a slide layer contacted with an inner circumferential surface of a pin unit so as to be rotatably supported; And a load supporting layer which is integrally laminated so as to surround the outer circumferential surface of the slide layer and which is held in contact with the inner circumferential surface of the boss to support a radial load of the pin unit, To 160 J, and an impact value of the slide layer is 60 to 180 J, to provide a bush having a double structure formed of a polymer composite material.

The impact load value of the load supporting layer is 80 to 120 J and the impact value of the slide layer is 100 to 140 J under a low temperature condition of -40 占 폚.

The present invention also provides a bearing assembly comprising a bush of a double structure formed of the polymer composite material.

The present invention relates to a bush made of a polymer composite material, which, unlike the conventional metallic bushes, can exhibit excellent elasticity and recoverability under operating conditions of low speed and high load, Therefore, it is possible to prevent abnormal wear due to stress concentration and breakage due to impact, so that the wear resistance and impact resistance can be improved and the life characteristics can be improved.

According to the present invention, the outer circumferential surface of the slide layer contacting the pin unit in contact with the inner circumferential surface is integrally stacked so as to be surrounded by the inner circumferential surface of the boss and to support the load supporting layer supporting the radial load of the pin unit. The bushes can be prevented from being damaged or cracked even when an impact is applied to the bushes under a low temperature condition, so that the life characteristics of the bushes can be improved, it is possible to continuously exhibit excellent lubrication characteristics without greasing.

1 is a view showing an example of a joint part to which a bush can be applied in a general excavator and an excavator.
Fig. 2 is a cross-sectional view showing a conventional bush applied to the joint shown in Fig. 1 in the direction perpendicular to the longitudinal direction of the pin.
3 is a cross-sectional view of a bush according to the present invention.
FIG. 4 is a cross-sectional view of a bush with a double structure according to the present invention applied to the joint disclosed in FIG. 1, in a direction perpendicular to the longitudinal direction of the pin.
FIG. 5 is a longitudinal sectional view of a bush with a double structure according to the present invention applied to the joint disclosed in FIG. 1; FIG.

Hereinafter, the present invention will be described.

The present invention relates to a bush made of a polymer composite material and comprising a slide layer which is received in contact with an inner circumferential surface so as to be rotatably supported by the pin unit and which is integrally laminated so as to surround the outer circumferential surface of the slide layer and is accommodated in contact with the inner circumferential surface of the boss, And a load supporting layer for supporting a radial load, wherein the impact value of the load supporting layer and the slide layer is adjusted to a specific range under a low temperature condition (about -40 DEG C).

The present inventors have found that when a bush is manufactured using a polymer composite material comprising a polymer matrix, a fiber substrate and magnetic lubricating particles, unlike a conventional metal bush or a porous sintered bush, high elasticity is maintained under operating conditions of low- I knew I could recover when I was unauthorized. In addition, since the bush made of the polymer composite material can maintain a low coefficient of friction continuously due to the self-lubricating particles, unlike the conventional bushes, it is possible to maintain an excellent lubricating environment without periodic greasing.

Construction machines are generally used in polar regions and tropical regions. Therefore, a construction machine requires a wide usable temperature, as well as a high level of surface pressure and a high level of resistance. Therefore, it is very difficult to manufacture a bush using a polymer composite instead of a metal. Moreover, since most of the existing mechanical parts that come into contact or interact with the bush are made of cast steel or steel, the manufacture of bushes made of polymeric composites, A problem that has not occurred in the past can be caused. Particularly, in the case of a polymer composite material, unlike a metal, it is likely to be deformed by temperature change. Therefore, unless the temperature dependency of such a polymer composite material is taken into consideration, it is difficult to use a bush made of a polymer composite material under the conditions of use of a wide range of construction machines as described above.

Accordingly, in the present invention, a second polymer matrix and a second fiber substrate are laminated on the outer surface of a layer made of a first polymer composite material (hereinafter referred to as a 'slide layer') comprising a first polymer matrix, a first fiber substrate, (Hereinafter referred to as " load supporting layer ") are integrally laminated by using the second polymer composite material including the second polymer composite material. At this time, while controlling the strength and impact characteristics of the slide layer and the load supporting layer by controlling the contents of the respective components of the first and second polymer composite materials, particularly the contents of the first and second fiber substrates, Are set to respective specific ranges.

As a result, the bush having a double structure according to the present invention can be improved in wear resistance, impact resistance, and load resistance while maintaining excellent lubrication characteristics, thereby improving lifetime characteristics. In particular, the dual structure bushings of the present invention can be used in a wide range of temperature conditions and can be stably used under a wide range of conditions after being pressed into a boss of a housing. In addition, since the bush of the double structure has no deformation in the slide layer even if an unbalanced load is caused by unspecified operating conditions, the lifetime can be further improved as compared with the conventional metal bush.

Specifically, the bush having a dual structure according to the present invention includes the load supporting layer formed integrally with the slide layer, so that it has an excellent load-bearing property under high-load operating conditions and has excellent lubrication characteristics without periodic greasing It can be maintained continuously.

However, like the bush-shaped metal bush having the double structure made of the polymer composite material according to the present invention, the bush is machined to a tolerance level larger than the inner diameter of the boss of the housing, and then forcedly fitted and fixed to the boss of the housing by forced- Is used. Therefore, the bush with a double structure according to the present invention should be minimized in deformation due to external temperature. Particularly, in the case of the load supporting layer, since it is used by being forcedly inserted into the boss of the housing, there is no need for any deformation under the use temperature condition in order to maintain the pressure input with the housing. In addition, since the outer peripheral surface of the load supporting layer and the inner peripheral surface of the boss may become loose when in use after the bush is press-fitted, the load supporting layer must maintain a high friction coefficient at all times with respect to the inner surface of the boss of the housing.

Accordingly, in the present invention, by adjusting the content of each component in the second polymer composite material forming the load supporting layer in the production of the load supporting layer to a specific range, the impact load value of the load supporting layer under the low temperature condition of -40 ° C is set in the range of about 40 to 160 J, Preferably in the range of 80 to 120 J. If the impact load value of the load support layer under a low temperature condition of -40 캜 is less than 40 J, the brittleness increases and cracks may be generated in the load support layer or the load support layer may be damaged under an impact condition such as a hydraulic breaker. On the other hand, when the impact load value of the load support layer is lower than -60 ° C under a low temperature condition of -40 ° C, the load support layer is not fixed to the inner surface of the boss due to local deformation and friction reduction under high- have.

In addition, in the double structure bush according to the present invention, the slide layer always makes contact with the pin and performs relative motion. Loads and impacts are directly transmitted to these slide layers through pins. Therefore, if the impact value of the slide layer is not designed to be higher than a certain level, the slide layer may be rapidly broken or the slide layer may crack due to impact and load concentration in a local area such as an offset load under unspecified working conditions.

Accordingly, in the present invention, the content of each component in the first polymer composite material forming the slide layer in the production of the slide layer is adjusted to a specific range, and the impact value of the slide layer under the low temperature condition of -40 ° C is set in the range of about 60 to 180 J , Preferably in the range of about 100 to 140 J. If the impact value of the slide layer under a low temperature condition of -40 占 폚 is less than 60 J, the inner circumferential surface of the slide layer may be broken or a crack may be generated in the slide layer under the high load and continuous use conditions and the life of the bushing may be deteriorated. On the other hand, when the impact value of the slide layer under the low temperature condition of -40 캜 exceeds 180 J, the friction during the relative motion with the pin under the high load condition increases and the wear rate of the slide layer increases, .

The bush 100 according to the present invention is made of a polymer composite material and is applied to a front joint part of a construction machine to support a load and realize a swing motion. The bushing 100 has a space for accommodating the pin unit 200 therein and is relatively movable with respect to the pin unit. The slide unit 101 and the load supporting layer 102 .

The slide layer 101 contacts the inner circumferential surface so that the pin unit 200 can be rotatably supported. This slide layer 101 comprises a first polymer matrix; Self-lubricating material; And a first fibrous base material. The mixing ratio of the first polymer matrix, the self-lubricating particles and the first fiber substrate is 20 to 22:20 to 55:23 to 29, preferably 20.5 to 21.5: 20.5 to 53.5: 25 to 27.5 , The slide layer is controlled to have an impact value in a range of about 60 to 180 J, preferably about 100 to 140 J under a low temperature condition of -40 ° C. Since such a slide layer exhibits excellent elasticity and recoverability and can maintain excellent lubrication characteristics without periodic feeding, the low friction characteristic can be maintained, and the pin unit 101, which is received in contact with the inner circumferential surface, smoothly rotates . In addition, the slide layer is not broken even under high load and continuous use conditions, and cracks are not generated. Further, since friction is small during relative motion with the fins, the slide layer is less worn and the life of the bush can be improved.

The first polymer matrix can improve the thermal and chemical stability of the slide layer. Examples of the first polymer matrix include, but are not limited to, an epoxy polymer, a polyurethane polymer, a polyamide polymer, a polyalphaolefin polymer, a vinyl polymer, an acrylic polymer, a polyacetal polymer, a polyether polymer, Based polymers, polyether-based polymers, polyether sulfone-based polymers, polysulfide-based polymers, polyimide-based polymers, polypeptide-based polymers, polyketone-based polymers, polyolefin-based polymers, polyimide-based polymers, vinylidene-based polymers, and copolymers thereof These may be used alone or in combination of two or more. Among them, in the case of the epoxy-based polymer, the curing speed in the production of the bushing is high, so that the productivity can be improved and the thermal stability and chemical stability of the bushing can be further improved. However, when a polymer having compatibility with the second polymer matrix is used as the first polymer matrix, the polymer matrix of the both layers diffuse or covalently bond with each other at the interface between the slide layer and the load support layer, The lower load supporting layer can be more easily laminated integrally on the slide layer. Further, when compatible polymer matrices are used, since the curing conditions are similar, it is not necessary to separately cure each layer, and thus the working speed can be improved.

In addition, the first polymer composite material includes self-lubricative particles. The self-lubricating particles are solid particles having low frictional resistance even without a lubricant and are capable of preventing the inner peripheral surface of the slide layer from being abraded or burned when the inner peripheral surface of the slide layer is relatively moved with respect to the pin, have.

These non-limiting examples of self-lubricating particles _{Graphite, Graphite fluoride, MoS 2,} MoSe 2, WS 2, WSe 2, NbS 2, NbSe 2, TaS, TaSe 2, TiS 2, TiSe 2, TiTe 2, CeF 3, _{Ba (OH) 2, CdCl 2} , CoCl 2, ZrCl 2, PbCl 2, PbI 2, BN, Ag 2 SO 4, Borax (Na 2 B 4 O 7), Talc [Mg 3 (OH) 2 Si 2 O 10 _{], Mica [KAl 2 (Si} 3 Al) O 10 (OH) 2], ZnS, SnS 2, FeS, CaF 2, LiF, Zn 2 P 2 O 7, Ca 3 (PO 4) 2, Fe 2 P 2 _{O 7, Ca (OH) 2} , Mg (OH) 2, Zn (OH) 2, PbO, ZnO, FeO, Fe 2 O 3, Fe 3 O 4, polytetrafluoroethylene (PTFE), Fluorinated ethylene propylene (FEP), Pb , Sn, Zn, Cu, Ag, and In. Of these, graphite, PTFE or a mixture thereof is preferable, and PTFE is more preferable.

As the self-lubricating particles, magnetic lubricating particles of a resin type such as PTFE and the like can be mixed with magnetic lubricating particles of a non-resin type such as graphite. In this case, the mixing ratio of the resin-type magnetic lubricating particles to the non-resin-type magnetic lubricating particles is not particularly limited, but is preferably 10 to 90:90 to 10, preferably 20 to 70:30 to 80, In the case of the weight ratio, not only the lubrication characteristics of the bush, but also the abrasion resistance and the load resistance can be further improved.

In addition, the first polymer composite material includes a first fiber substrate. By including the first fiber substrate, the strength of the slide layer can be improved.

Examples of such first fiber substrates include yarns, woven fabrics, knits, and braids. Among them, when a fabric is used, the thickness of the slide layer The workability can be improved. In addition, unlike a knitted fabric or a braid, when a fabric is wound around a mandrel to form a slide layer, shear deformation is difficult, so that the slide layer is formed in a uniform thickness and shape. Therefore, It can have strength.

The material (fiber) of the first fiber substrate is not particularly limited, and examples thereof include vegetable fibers such as cotton, hemp, and the like; Animal fibers such as hair, dogs and the like; Regenerated fibers such as rayon and the like; Synthetic fibers such as polyester, acrylic, nylon, polyurethane and the like; Inorganic fibers such as glass fibers and carbon fibers, and metal fibers. These fibers may be used alone or in combination of two or more. Among them, inorganic fibers such as glass fiber and carbon fiber have low water content, so that pores are not formed in the subsequent curing and excellent in thermal stability. Therefore, when a fabric made of inorganic fibers is used, the strength and thermal stability of the final bush can be improved.

The first polymer composite material may further include additives such as an initiator, a diluent, and the like in order to further improve the physical properties of the slide layer, if necessary, as long as the lubricating properties of the slide layer are not affected, in addition to the above- .

The initiator may be appropriately selected according to the type of the first polymer matrix, and examples thereof include a benzo phenone initiator, a thioxanthone initiator, an a-hydroxyketone initiator, an a-amino ketone initiator, a benzyl dimethyl ketal, BDK ), phenyl glyoxylate type, and acyl phosphine oxide type.

Examples of the diluent include Butyl Glycidyl Ether (BGE), Phenyl Glycidyl Ether (PGE), Aliphatic Glycidyl Ether (C12-C14), Modifide-Tert-Carboxylic Dlycidyl Ester, DiButyl Phthalate (DBP), DiOctyl Phthalate But is not limited thereto.

In addition, in order to improve the physical properties upon curing and to adjust the bubble and the gloss, a very small amount of additives such as a defoaming agent, a viscosity adjusting agent, a wetting agent, a gloss control agent and the like may be included.

The content of the initiator, diluent, and other additives is not particularly limited and may be about 1 to 10 parts by weight based on 100 parts by weight of the first polymer matrix, respectively.

The bushing 100 according to the present invention includes a load supporting layer 102 integrally laminated on the slide layer 101 so as to surround the outer circumferential surface of the slide layer 101, as shown in FIGS. The load supporting layer 102 is received in contact with the inner circumferential surface of the boss 300 to support the radial load of the pin unit 200.

This load bearing layer 102 is formed of a second polymeric composite material comprising a second polymer matrix and a second fiber substrate. When the mixing ratio of the second polymer matrix to the second fiber substrate is controlled to be 20 to 21.5: 78.5 to 80, preferably 20.4 to 21: 79 to 79.6, The impact value under low-temperature conditions is controlled in the range of about 40 to 160 J, preferably about 80 to 120 J. As a result, the load supporting layer becomes brittle and does not crack under impact conditions such as an oil pressure breaker, is not broken, and is not deformed even under high temperature and high load and continuous use conditions of 60 DEG C or more, so that the life of the bush can be improved . In addition, the load-bearing layer not only can compensate the load-bearing property of the slide layer but also can be improved in elasticity and recoverability even when an offset load is generated by the pin unit when it is received in contact with the inner circumferential surface of the boss, And further, life characteristics can be improved.

The second polymer matrix can improve the thermal and chemical stability of the load supporting layer. Non-limiting examples of the second polymer matrix include epoxy-based polymers, polyurethane-based polymers, polyamide-based polymers, polyalphaolefin-based polymers, vinyl-based polymers, acrylic polymers, polyacetal-based polymers, polyether- There may be mentioned a polymer, a polyether sulfone type polymer, a polysulfide type polymer, a polyimide type polymer, a polypeptide type polymer, a polyketone type polymer, a polyolefin type polymer, a polyimide type polymer, a vinylidene type polymer, They may be used alone or in combination of two or more. Among them, in the case of the epoxy-based polymer, the curing speed in the production of the bushing is high and the productivity can be improved, and the thermal stability and the chemical stability of the bushing can be improved. However, as described above, when a polymer having compatibility with the first polymer matrix is used as the second polymer matrix, the second polymer matrix of the load supporting layer at the interface between the slide layer and the load supporting layer is injected into the surface of the slide layer Or can be covalently bonded to the first polymer matrix of the slide layer, so that the load bearing layer can be easily laminated integrally to the slide layer.

In addition, the second polymer composite material includes a second fiber substrate. The second fiber substrate improves the strength of the load supporting layer to compensate the load-bearing property of the slide layer.

Such a second fiber substrate may be a yarn, a woven fabric, a knitting, and a braid as well as the first fiber substrate. Among them, when the fabric is used, the thickness of the load supporting layer can be easily adjusted in the production of the bush through the filament winding method, so that the workability can be improved, and even when the fabric is wound on the mandrel or slide layer, Unlike a braid, shear deformation is not easy, so that it is formed in the same thickness and shape, so that the load supporting layer can have a uniformly uniform strength as a whole.

The material (fiber) of the second fiber substrate is not particularly limited, and examples thereof include vegetable fibers such as cotton, hemp, and the like; Animal fibers such as hair, dogs and the like; Regenerated fibers such as rayon and the like; Synthetic fibers such as polyester, acrylic, nylon, polyurethane and the like; Inorganic fibers such as glass fibers and carbon fibers, and metal fibers. These fibers may be used alone or in combination of two or more. Among them, inorganic fibers such as glass fiber and carbon fiber have low water content, so that pores are not formed in the subsequent curing and excellent in thermal stability. Therefore, when a fabric made of inorganic fibers is used, the strength and thermal stability of the final bush can be improved.

In addition to the above-mentioned components, the second polymer composite material may further contain additives such as an initiator, a dispersant, an antifoaming agent, and the like in order to further improve the physical properties of the load-supporting layer within a range that does not impair properties such as load- As shown in FIG.

The initiator is appropriately selected according to the type of the second polymer matrix, and examples thereof include a benzo phenone-based initiator, a thioxanthone-based initiator, an a-hydroxyketone-based initiator, an a-amino ketone-based initiator, a benzyl dimethyl ketal ), phenyl glyoxylate type, and acyl phosphine oxide type.

The content of the initiator is not particularly limited and may be about 1 to 10 parts by weight based on 100 parts by weight of the second polymer matrix.

As described above, according to the present invention, since the bush having a double structure made of a polymer composite material has a seizure cycle of 250,000 cycles or more and a pressure limit of indentation maintenance at 60 DEG C of 90 to 100 MPa, a surface pressure of 2 to 6 kgf / And a sliding speed of 0.25 to 3.5 cm / sec.

Meanwhile, the bush of the double structure according to the present invention can be manufactured by various methods.

According to one example of the present invention, a dual structure bushing comprises a first polymer matrix, a self-lubricating particle and a first fiber substrate, wherein the bush comprises a first polymer matrix, Forming a first polymer composite material by adjusting a usage ratio of the first polymer matrix, the self-lubricating particles, and the first fiber substrate to a specific range; A second polymer matrix and a second fiber substrate, wherein the use ratio of the second polymer matrix and the second fiber substrate is adjusted to a specific range so that the impact value of the load supporting layer under a low temperature condition of 40 ° C is 40 to 160 J Forming a second polymer composite material; Winding the first polymeric composite material on a mandrel so as to form a slide layer having a desired thickness; Winding a second polymeric composite material wound on the first polymeric composite material to form a load supporting layer having a desired thickness; And a step of curing the wound first polymer composite material and the second polymer composite material. After the curing step, cutting may be performed according to the shape of the final bush. Further, after the curing step, machining the inner peripheral surface of the slide layer of the final bush and / or the outer peripheral surface of the load supporting layer may be further machined.

According to another example of the present invention, a dual structure bushing comprises a first polymer matrix, self-lubricating particles and a first fiber substrate, wherein the impact value of the slide layer under a low temperature condition of -40 占 폚 is about 60 to 180 占Forming a first polymer composite material by adjusting a usage ratio of the first polymer matrix, the self-lubricating particles, and the first fiber substrate to a specific range; A second polymer matrix and a second fiber substrate, wherein the use ratio of the second polymer matrix and the second fiber substrate is adjusted to a specific range so that the impact value of the load supporting layer under a low temperature condition of 40 ° C is 40 to 160 J Forming a second polymer composite material; Winding the first polymeric composite material on a mandrel to form a slide layer having a desired thickness; Curing the first polymeric composite material wound on the mandrel to form a slide layer; Winding the second polymeric composite material on the slide layer so as to form a load supporting layer having a desired thickness; And curing the wound second polymer composite material to form a load supporting layer. After the step of forming the load supporting layer, cutting may be performed according to the shape of the final bush. Further, after the step of forming the load supporting layer, the step of machining the inner peripheral surface of the slide layer of the final bush and / or the outer peripheral surface of the load supporting layer may be further included.

First, a first polymer composite material including a first polymer matrix, a self-lubricating particle, and a first fiber substrate is formed (S100).

In the step S100, the self-lubricating particles are added to the first polymer matrix to form a resin composition; Woven the first fiber substrate using fibers; And impregnating the resin composition with the woven first fibrous substrate.

At this time, the usage ratio of the first polymer matrix, the self-lubricating particles, and the first fiber substrate is set such that the impact value of the slide layer formed of the first polymer composite material is in the range of 60 to 180 J under a low temperature condition of -40 ° C Adjust to a specific range.

It is appropriate to control the type of fiber, the thickness of the yarn, and the like in accordance with the strength, elastic modulus, fatigue life, thickness, etc. of the final slide layer at the time of weaving the first fiber substrate.

A second polymer composite material including the second polymer matrix and the second fiber substrate is formed (S200) regardless of the pre-alignment with the step S100.

The step S200 includes: weaving the second fiber substrate using fibers; And impregnating the woven second fibrous substrate with the second polymeric matrix.

At this time, the usage ratio of the second polymer matrix and the second fiber substrate is adjusted to a specific range so that the impact value of the load supporting layer formed of the second polymer composite material is in the range of 40 to 160 J under a low temperature condition of -40 ° C .

In the weaving of the second fibrous base material, the type of fiber, the thickness of the yarn, and the like are appropriately adjusted in consideration of the thickness, strength, elastic modulus, fatigue life, etc. of the final load supporting layer.

Thereafter, the first polymeric composite material formed in step S100 is wound on a mandrel to form a slide layer 101 (S300). At this time, the number of winding and winding angle of the first polymeric composite material in the mandrel is adjusted so that a slide layer having a desired thickness is formed.

On the other hand, if the first polymer matrix of the slide layer and the second polymer matrix of the load supporting layer are incompatible, a step of winding the first polymer composite material on the mandrel and then curing the wound first polymer composite material .

The curing temperature and time are not particularly limited and it is preferable to adjust the curing temperature and time in consideration of the kind of the initiator, the kind of the first polymer matrix, the kind of the first fiber base material, the thickness of the first polymer composite material, For example, when an aromatic polyamine-based initiator is used, the first polymer composite material can be cured by heating at a temperature of about 130 ° C to 150 ° C for about 10 to 30 minutes. In this case, the shrinkage can be minimized and the strength can be improved by post-curing at the temperature condition that is semi-cured at room temperature for about one day.

Next, the second polymer composite material formed in step S200 is wound around the slide layer formed in step S300 to form a load supporting layer (S400). At this time, the number of times of winding the second polymeric composite material on the slide layer is controlled to be one layer (one layer) or more so that a desired load supporting layer is formed. In addition, the winding angle of the second composite bar composite is controlled in consideration of the desired strength of the load supporting layer.

Thereafter, the wound first polymer composite material and the second polymer composite material are cured (S500). As a result, a double-structure bush made of a polymer composite material including the slide layer 101 and the load supporting layer 102 integrally stacked on the outer peripheral surface of the slide layer is obtained.

The curing temperature and time are not particularly limited. As with the first polymer composite material, the kind of the initiator, the kind of the first and second polymer matrix, the kind of the first and second fiber substrates, the first and second polymer composite The thickness of the material, the number of times of winding, and the like. For example, when an aromatic polyamine-based initiator is used, the first polymer composite material and the second polymer composite material can be cured by heating at a temperature of about 130 to 150 ° C for about 10 to 30 minutes.

However, if the curing step for the first polymer composite material is performed separately, the second polymer composite material is cured by controlling the curing temperature and time so that the already formed cured slide layer is not deteriorated.

Meanwhile, the bush obtained after the step S500 can be cut according to a desired length.

In addition, the pin unit 200 can be smoothly rotated by machining the inner peripheral surface of the slide layer of the bush obtained after the step S500 so as to have an appropriate tolerance level. Further, the outer circumferential surface of the load supporting layer of the bush may be machined so as to have an appropriate tolerance level so that the bush of the present invention can be fixed to the inner circumferential surface of the boss 300 without any rotation between press-

The present invention, on the other hand, provides a bearing assembly (not shown) having a bushing 200 of the above-described dual structure. As the bearing assembly, for example, the pin unit 200 may be inserted into the inner circumferential surface of the bush 200 having a double structure.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the following examples serve to illustrate the present invention, and the scope of the present invention is not limited thereto.

[ Example  One]

A woven fabric using polyester fibers was impregnated with a resin composition containing epoxy resin, graphite and PTFE particles (polytetrafluoro ethylene particles) to obtain a first polymer composite material, which was then impregnated with a mandrel (diameter: 71 mm ) To form a slide layer. At this time, the mixing ratio of the epoxy resin, graphite, PTFE and polyester fiber fabric of the first polymer composite material was adjusted to a weight ratio of 20.4: 30.6: 20.4: 28.6. Thereafter, the woven fabric is impregnated with the epoxy resin by using glass fiber to obtain a second polymer composite material, which is wound on a slide layer formed on the surface of the mandrel to form a load supporting layer, followed by heating and curing to form a double- : 10 mm, outer diameter: 86 mm, length: 60 mm). At this time, the mixing ratio of the epoxy resin of the second polymer composite material and the glass fiber fabric was adjusted to a weight ratio of 20:80.

[Example 2]

The mixing ratio of the epoxy resin, graphite, PTFE particles and polyester fiber fabric of the first polymer composite material used in Example 1 was adjusted to 20.8: 31.3: 20.8: 27.1 by weight ratio instead of 20.4: 30.6: 20.4: 28.6 And that the mixing ratio of the epoxy resin of the second polymer composite material and the glass fiber cloth was adjusted to 20.4: 79.6 by weight instead of 20: 80 by weight, .

[Example 3]

The mixing ratio of the epoxy resin, graphite, PTFE particles and polyester fiber fabric of the first polymer composite material used in Example 1 was adjusted to a weight ratio of 21.3: 31.9: 21.3: 25.5 instead of 20.4: 30.6: 20.4: 28.6 weight ratio , And a double-structure bush was obtained in the same manner as in Example 1, except that the mixing ratio of the epoxy resin of the second polymer composite material and the glass fiber cloth was adjusted to 20.8: 79.2 by weight instead of 20: 80 .

[Example 4]

The mixing ratio of the epoxy resin, graphite, PTFE particles and polyester fiber fabric of the first polymer composite material used in Example 1 was adjusted to a weight ratio of 21.7: 32.6: 21.7: 24 instead of 20.4: 30.6: 20.4: 28.6 weight ratio , And a double-structure bush was obtained in the same manner as in Example 1, except that the mixing ratio of the epoxy resin of the second polymer composite material and the glass fiber fabric was adjusted to 21.3: 78.7 by weight instead of 20: 80 by weight .

[Comparative Example 1]

A bush made of structural carbon steel (SCM440) treated with surface roughening and MoS ₂ soft coating was used as Comparative Example 1.

[Comparative Example 2]

A Fe-Cu-based porous sintered bush was used as Comparative Example 2.

[Comparative Example 3]

The mixing ratio of the epoxy resin, graphite, PTFE particles and polyester fiber fabric of the first polymer composite material used in Example 1 was adjusted to 20: 30: 20: 30 weight ratio instead of 20.4: 30.6: 20.4: 28.6 weight ratio , And a double-structure bush was obtained in the same manner as in Example 1, except that the mixing ratio of the epoxy resin of the second polymer composite material and the glass fiber cloth was adjusted to the ratio of 19.6: 80.4 by weight instead of 20: 80 by weight .

[Comparative Example 4]

The mixing ratio of the epoxy resin, graphite, PTFE particles and polyester fiber fabric of the first polymer composite material used in Example 1 was adjusted to 20: 30: 30: 20 weight ratio instead of 20.4: 30.6: 20.4: 28.6 weight ratio , And a double structure bush was obtained in the same manner as in Example 1 except that the mixing ratio of the epoxy resin of the second polymer composite material and the glass fiber cloth was adjusted to a weight ratio of 21.7: 78.3 instead of 20: 80 .

[Comparative Example 5]

The mixing ratio of the epoxy resin, graphite, PTFE particles and polyester fiber fabric of the first polymer composite material used in Example 1 was adjusted to 20.4: 30.6: 30.6: 18.4 by weight ratio instead of 20.4: 30.6: 20.4: 28.6: , A bush of a double structure was obtained in the same manner as in Example 1 except that the mixing ratio of the epoxy resin of the second polymer composite material and the glass fiber cloth was adjusted to a weight ratio of 22: 78 instead of 20: 80 .

[Comparative Example 6]

The mixing ratio of the epoxy resin, graphite, PTFE, and polyester fiber fabric of the first polymer composite material used in Example 1 was adjusted to 20.8: 31.25: 31.25: 16.7 weight ratio instead of 20.4: 30.6: 20.4: 28.6 weight ratio , And a double-structure bush was obtained in the same manner as in Example 1, except that the mixing ratio of the epoxy resin of the second polymer composite material to the glass fiber cloth was adjusted to a weight ratio of 22.2: 77.8 instead of 20: 80 .

[Experimental Example 1] - Property evaluation

The bushes prepared in Examples 1 to 4 and Comparative Examples 1 to 6 were measured for impact value, clamping amount at 60 ° C, indentation limit pressure at 60 ° C, friction coefficient, and seizure cycle. The measurement results are shown in Table 1 below.

1-1. Impact value

Test pieces (size: 10 x 10 x 55 mm) were prepared from the first polymer composite material and the second polymer composite material used in Examples 1 to 4, respectively. A V-shaped notch was formed at the center of each test piece, and the test piece was mounted horizontally on the support. Then, the energy (E) required to cut the test piece after the impact of the hammer of the Charpy impact tester was applied to the opposite side of the notch, and the angle at which the initial hammer was raised and the angle And then dividing it by the minimum cross-sectional area of the notch portion.

(In the above formula (1)

W is the weight of the hammer (Kg)

R is a distance (m) from the center of the rotation axis of the hammer to the center of the hammer,

Is the angle when the hammer is raised,

β is the angle at which the hammer rises after cutting the specimen).

1-2 Fastening

Each of the bushes was press-fitted into the boss of the housing, and the inner diameter of the shrunk bush was compared with the inner diameter of the bush before press-fitting, and the shrinkage of the bush inner diameter was measured. At this time, the shrinkage amount of the bush inner diameter is referred to as a clamping amount.

1-3 Indentation hold limit pressure

When the surface pressure is increased by applying a stepwise load at a non-lubricating atmosphere, a swing angle of 90 °, a swing speed of 1 m / min, and a temperature of 60 ° C, the pressure between the bush and boss decreases, The pressure was measured at the point of time when the pressure was maintained at the limit pressure.

1-4. Friction coefficient and Seizure cycle

The real time friction coefficient was measured under the non-lubricating atmosphere, the swing angle of 90 °, the swing speed of 1 m / min and the infinite cyclic loading condition of 1 to 21 tons, and the first cycle in which the coefficient of friction was 0.35 or more seizure cycle.

In the case of the bushings of Examples 1 to 4, the impact value of the load supporting layer under the low temperature condition (-40 占 폚) was about 40 to 160 J, and the impact value of the slide layer was about 60 to 180 J. The bushes of Examples 1 to 4 had higher pressures at 60 ° C than the bushings of Comparative Examples 1 and 2, and the seizure cycle was 260,000 cycles higher than those of Comparative Examples 1 and 2. In addition, the bushings of Examples 1 to 4 can be used to adjust the impact value of the load supporting layer under a low-temperature condition (-40 占 폚) outside the range of 40 to 160 J, The seizure cycle was superior to that of Comparative Examples 3 to 6 in which the value was controlled outside the range of 60 to 180 J (outside).

As described above, the bush having a double structure according to the present invention is able to withstand a high limit load due to its high limit pressure as compared with conventional bushings, has excellent seizure cycle of 250,000 cycles or more and excellent lubricity, Do.

10: joints, 11: conventional bushes,
12, 200: pin, 13, 300: boss,
100: bush of the present invention, 101: slide layer,
102: load supporting layer

Claims (6)

A slide layer contacting and holding the inner circumferential surface so that the pin unit can be rotatably supported; And
A load supporting layer which is integrally laminated so as to surround the outer circumferential surface of the slide layer and which is held in contact with the inner circumferential surface of the boss to support a radial load of the pin unit;
≪ / RTI >
A bush having a double structure formed of a polymer composite material having an impact value of 40 to 160 J under a low temperature condition of 40 DEG C and an impact value of 60 to 180 J in a slide layer; The method according to claim 1,
Wherein the impact load value of the load supporting layer is 80 to 120 J and the impact value of the slide layer is 100 to 140 J under a low temperature condition of -40 占 폚. The method according to claim 1,
Wherein the slide layer comprises: (a) a first polymer matrix; (b) a self-lubricating material; And (c) a first polymeric composite material comprising a first fiber substrate. The method according to claim 1,
Wherein the load bearing layer is formed of a second polymeric composite material comprising (a) a second polymer matrix, and (b) a second fiber substrate. The method according to claim 1,
A surface pressure of 2 to 6 kgf / mm < 2 > and a sliding speed of 0.25 to 5 cm / sec. A bearing assembly comprising a bush of a dual structure as claimed in any one of claims 1 to 5.

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