RU2095653C1 - Bearing with permanently lubricating layer and method of manufacturing same - Google Patents

Abstract

FIELD: mechanical engineering. SUBSTANCE: bearing consists of outer and inner races with ways and balls received in the races and arranged in the cage. The working surfaces of the parts of the bearing are covered with a polymer. EFFECT: increased longevity. 5 cl, 5 tbl, 6 dwg

Description

 The invention relates to mechanical engineering and can be used in the manufacture of bearings of various types. Rolling and sliding bearings are used in the construction of machines and devices in which they operate in a wide range of speeds, temperatures and loads. The wider use of rolling bearings is due to the lower moment of rotation resistance (compared with plain bearings). Rolling bearings have greater bearing capacity per unit of bearing bearing area, are characterized by ease of use and lower consumption of lubricants. At the same time, good lubricity of the bearing ensures its durability.

 Known rolling bearing / 1 /, having an outer and inner ring with raceways, between which are placed rolling bodies held by the separating element. Between the rings and the rolling elements of the bearing is a solid lubricant that is located on the surfaces of the raceways. As a solid lubricant, molybdenum disulfide, graphite and teflon are used.

 A disadvantage of the known bearing is that the transfer of solid lubricant to the contact points is uneven. As a result, an excessive amount of solid lubricant on the raceways leads to a decrease in the radial clearance between the bearing parts and, as a result, to jamming of the rolling bodies and to the destruction of the cage bridges.

 Also known are plain bearings and sliding elements / 2 /, which are used in heavily loaded working conditions. In this case, the sliding elements are made of stainless steel or a copper alloy, inside of which grease balls or materials such as graphite, ceramic, resin, asbestos, etc. are embedded.

 However, such elements do not have high strength, in particular impact resistance and durability.

 Also known is a rolling bearing / 3 /, adopted for the closest analogue, the lubricating layer of which is made in the form of a polymer coating of the working surfaces of the bearing parts. The polymer coating is made, for example, of polytetrafluorototidene.

 The disadvantage of this bearing is its relatively low durability, as well as a high level of vibration during operation, due to both a possible lack of compatibility between the applied working lubricants and the polymer coating material, resulting in a mutual reaction of the lubricants and material with the formation of solid particles, and the presence of significant roughness the surface of the coating, for example, due to the lack of operation of its running-in (rolling).

There is also a method of producing a lubricating layer by applying an antifriction polymer coating to the working surfaces of bearing parts, in which a polymer coating is applied from a water bath consisting of a dispersible acid (0.1 to 0.8 wt.) To a metal product connected to a positive electrode. . At the same time, the following operating modes are maintained: voltage from 30 to 300 V for 30 s to 10 min. Then the product is washed with water and heat treated at 130 300 ^o C for from 30 s to 60 min / 4 /.

 A disadvantage of the known method for producing a lubricating layer of a bearing is that the formation of the polymer coating occurs in an acidic environment, and this, when dried, causes the destruction of the polymer film and the destruction of the metal surface under the film. In addition, there is no lubricant in the coating itself, which reduces its tribological characteristics.

There is also a method of producing a lubricating layer in the form of a polymer coating on metal products, in particular on rolling bearings [5] adopted as the closest analogue, which is carried out by anodic electrodeposition on metal products from an aqueous solution containing emulsions of styrene-acrylate copolymers in an amount of 1, 8 8.0 wt. and sodium decahydroborate in an amount of 0.1 0.06 wt. The electrodeposition is carried out at a DC voltage of 3 30 V for 10 180 s. Then the product is washed with water and heat treated at 80 180 ^o C for 1-5 minutes and kept in lubricant or oil at 45-50 ^o C for 8 40 hours

The disadvantage of this method is the presence in the aqueous electrolyte solution of an additive of sodium decibibroborate, since its presence requires constant monitoring of the composition in the bath, which complicates the coating process. This is due to the fact that with an increase in the electrolyte of this component in an amount of more than 0.06 wt. excessive porosity of the surface appears, which can lead to the destruction of this coating and, accordingly, the lubricating layer. Moreover, the deposition time specified in this method may not be enough to obtain a significant coating thickness on large parts. In addition, the aging process in lubricant or oil at 45 50 ^o C for 8 40 hours is not technologically advanced and not economically feasible. Oils and greases are selected without regard to compatibility conditions with the working lubrication of the bearing, which can lead to a significant reduction in its service life. Since the surface of the polymer coating turns out to be rather rough, the absence of an operation to improve its quality, for example, by rolling, leads to significant vibrations and dynamic loads at the beginning of the operation of the bearing.

 The main objectives of the invention are the creation of a permanent lubricating layer between the contact surfaces of the bearing parts in order to increase its durability, stability under high loads and high speeds, as well as reducing the level of vibration during its operation. In addition, the task was to develop a method of manufacturing a bearing of the proposed design, which would ensure the ability of the polymer coating to hold on its surface an additional lubricating layer in the form of a thin film under various operating conditions of the bearing and high strength of this coating with its small value, as well as high antifriction qualities . Another objective is the creation of a method of manufacturing a bearing having high adaptability and process stability, in which a constant lubricating layer is obtained on the working surfaces of the bearing parts.

где γ₁ эталонная кинематическая вязкость для обеспечения нормальной смазываемости подшипника с учетом его нагрузки и режимов работы при эксплуатации, γ_cc кинематическая вязкость постоянного смазочного слоя, определяемая по формуле γ_cc= γ_п•(1-K_з)+γ_см•K_з где γ_п кинематическая вязкость полимерного слоя; γ_см кинематическая вязкость смазки, пропитывающей полимерный слой, K₃ V_cm/V_п - коэффициент заполнения смазкой полимерного слоя, где V_см объем внедренной в полимерный слой смазки, V_п объем осажденного полимерного слоя. При этом толщина полимерного слоя на дорожках качения наружного и внутреннего колец составляет 0,3 3,0 мкм, а толщина дополнительного смазочного слоя в виде пленки, удерживаемой на поверхностях полимерного слоя вследствие соблюдения условий совместимости применяемых смазок, составляет 0,5 5,0 мкм.This problem is solved in that in a bearing, for example, of a rolling element, consisting of an outer ring provided with an inwardly facing annular raceway, and an inner ring provided with an outwardly facing annular raceway, between which rolling bodies are placed, for example balls kept at a certain distance from each other from each other using, for example, a metal separator. A polymer layer impregnated with grease is applied to the working surfaces of these bearing parts. The polymer layer is made of anode-electrodeposited material such as styrene-acrylate copolymers, and the impregnating lubricant is selected compatible with the working lubricant of the bearing so that, taking into account the load conditions and operating conditions during operation of the bearing, an additional lubricant layer is formed on the surfaces of the polymer layer in the form of a thin film. Moreover, the compatibility of these lubricants is provided by their mutual selection based on a comparison of the compatibility of the base thickeners of these lubricants. The rolling friction coefficient of the obtained lubricant mixture f is in the range 0 <f <0.05 when testing this mixture for at least 2 hours. Its penetration is in the range P _max >P> P _min , where P _max and P _min penetration values of said mixed lubricants. Another condition for choosing a lubricant impregnating the polymer layer may be the ratio of the kinematic viscosities

where γ _{1 is the} reference kinematic viscosity to ensure normal lubricity of the bearing, taking into account its load and operating conditions during operation, γ _{cc is the} kinematic viscosity of the constant lubricating layer, determined by the formula γ _cc = γ _p • (1-K _s ) + γ _cm • K _s where γ _{p the} kinematic viscosity of the polymer layer; γ _cm kinematic viscosity of the lubricant impregnating the polymer layer, K ₃ V _cm / V _p - filling factor of the polymer layer with grease, where V _{cm is the} volume of lubricant embedded in the polymer layer, V _{p is the} volume of the deposited polymer layer. In this case, the thickness of the polymer layer on the raceways of the outer and inner rings is 0.3 3.0 μm, and the thickness of the additional lubricant layer in the form of a film held on the surfaces of the polymer layer due to the compatibility conditions of the applied lubricants is 0.5 5.0 μm .

The proposed method of manufacturing bearings is that the bearing parts are placed in an aqueous emulsion of styrene-acrylate copolymers taken in a volume of 1.8 to 8.0 wt. and carry out anode electrodeposition on the working surfaces of the bearing parts for 3 300 s, after which the parts are subjected to heat treatment for 1 10 minutes. The resulting polymer layer is saturated with a lubricant compatible with the working lubricant selected according to the operating conditions of the bearing, and the bearing parts are subjected to secondary heat treatment at 80-150 ^° C for 10-60 minutes. Then carry out the rolling of the working surfaces of the bearing parts for 5 120 minutes

 In FIG. 1 shows a general view of a rolling bearing with a constant lubricating layer; in FIG. 2, a cross section AA in FIG. one; figure 3 General view of a half of the separator with a polymer layer; figure 4 is a structural diagram of the rolling bearing with an additional lubricating layer in section along the raceways; figure 5 nomogram of the dependence of the reference kinematic viscosity of the working lubricant of the bearing on its diameter and mode of operation; figure 6 is a diagram of the dependence of the level of vibration over time during tests of the bearing 2-36202K.

 The rolling bearing with a constant lubricating layer consists of an outer ring 1 and an inner ring 2, between which rolling bodies 3 are placed, placed in the cage 4. The outer ring 1 is provided with a raceway facing inward, on the surface of which a polymer layer 5 impregnated with grease is applied. The inner ring 2 is provided with a raceway facing outward, on the surface of which a polymer layer 6 impregnated with grease is applied. The same polymer layer is applied to the windows of the separator 4 (see figure 3). The polymer layer is made of anodically electrodeposited material such as styrene-acrylate copolymers. The lubricant impregnating the polymer layer is selected compatible with the working lubricant of the bearing so that, taking into account the load conditions and operating conditions during operation of the bearing, an additional lubricant layer 7 is formed and held on all surfaces of the polymer layer (Fig. 4).

 The compatibility conditions of the two lubricants used in the proposed bearing, i.e., the lubricant impregnating the polymer layer and the working lubricant of the bearing, were carefully developed by the authors and verified by numerous laboratories by testing and operating such bearings with a constant lubricating layer in a production environment.

(3),
где γ₁ эталонная кинематическая вязкость для обеспечения нормальной смазываемости подшипника. Ее значения можно получить, например, из монограммы на фиг.5 в зависимости от размеров подшипника и числа его оборотов при эксплуатации; γ_cc кинематическая вязкость постоянного смазочного слоя. Значение величины γ_cc определяется по формуле
γ_cc= γ_п•(1-K_з)+γ_см•K_з, (4)
где γ_п кинематическая вязкость полимерного слоя;
γ_см кинематическая вязкость смазки, пропитывающей полимерный слой;
K₃ V_см/V_n коэффициент заполнения смазкой полимерного слоя;
V_см объем смазки, внедренной в полимерный слой;
V_n объем осажденного полимерного слоя.The compatibility of lubricants is understood as the possibility of their intermixing with the formation of a uniform lubricant mixture. Lack of compatibility is characterized by the formation of either too thick grease, i.e. it hardens, or is too soft (liquid), as a result of which it flows out of the bearing. One of the indicators of compatibility ensuring normal mixing of lubricants can be the rolling friction coefficient f, measured when testing a mixture or bearing with a constant lubricating layer, rotating under load with working lubricant for at least 2 hours. It should be in the range 0 <f < 0.05 (I), which ensures the absence of solidification of the lubricant mixture. Another indicator of the compatibility of lubricants may be the value of the penetration of these lubricants P, which characterizes the viscosity of the mixture. This value should be within P _max >P> P _min (2), where P _max is the maximum penetration of one of the mixed lubricants, P _min is the minimum penetration of one of the mixed lubricants. This value of the penetration of the mixture ensures the absence of liquefaction during the operation of the bearing. In addition, the choice of lubricant impregnating the polymer layer, according to the conditions of bearing loading, is carried out according to the values of the reference kinematic viscosity of the lubricants. It will be different for heavily loaded bearings, high speed, high temperature, etc. To ensure normal lubricity, the following condition for the ratio of kinematic viscosities must be observed:

(3)
where γ _{1 is the} reference kinematic viscosity to ensure normal lubricity of the bearing. Its values can be obtained, for example, from the monogram in figure 5, depending on the size of the bearing and the number of its revolutions during operation; γ _cc kinematic viscosity of a permanent lubricating layer. The value of γ _cc is determined by the formula
γ _cc = γ _p • (1-K _s ) + γ _cm • K _s , (4)
where γ _{p the} kinematic viscosity of the polymer layer;
γ _cm kinematic viscosity of the lubricant impregnating the polymer layer;
K ₃ V _cm / V _n filling factor of the polymer layer with grease;
V _{cm the} amount of lubricant embedded in the polymer layer;
V _{n the} volume of the deposited polymer layer.

 Table 1 shows examples of the compatibility of intermixed lubricants.

 Table 2 shows the characteristics and examples of the use of lubricants for bearings operating in various conditions in terms of load and operating conditions.

 The proposed method of choosing lubricants according to compatibility criteria allows you to select the necessary lubricants, the interaction of which ensures the formation and retention of an additional lubricant layer on the surfaces of the polymer layer and guarantees highly efficient operation of the bearing under various loading conditions and operating conditions.

 The thickness of the deposited polymer layer is set to a certain value for the rolling bearing rings and depends on the loading conditions, the allowable surface roughness, as well as the processability of electrodeposition, which allows it to be controlled within certain limits. Typically, for the proposed bearing, it is 0.3 to 3.0 μm. With a thickness of less than 0.3 μm, the deposition process becomes unstable, and with a thickness of more than 3.0 μm, the strength of the polymer layer decreases and it can be destroyed with significant bearing loads. In addition, with such layer thicknesses, the degree of surface roughness increases, leading to increased noise and vibration. The increase in roughness on the surfaces of the raceways is not completely eliminated during the rolling operation, to which the bearing rings are subsequently subjected, which can lead to their rejection according to vibroacoustic requirements. The thickness of the polymer layer of the metal separator operating under sliding friction conditions can be significantly larger. Based on production experience, establish the thickness of the polymer layer of the metal cage from 6 to 50 microns for cages of large bearings.

 Such an electrodepositable polymer layer impregnated with a compatible lubricant is able to hold an additional lubricant layer in the form of a film with a thickness of 0.5 to 5.0 μm on its surface.

A method of manufacturing the proposed bearing is that the bearing parts are placed in an aqueous solution containing an emulsion of styrene-acrylate copolymers in an amount of 1.8 to 8.0 wt. without the addition of sodium decahydroborate. Electrodeposition is carried out at a DC voltage of 3 20 V for 3 300 s. Then the product is washed with water and heat treated at 130 300 ^o C for 1 10 minutes The resulting polymer layer is saturated with a lubricant compatible with the working lubricant of the bearing and selected from the conditions of its loading, the parts are subjected to secondary heat treatment to introduce the lubricant into the coating at 80-150 ^° C for 10-60 minutes. To eliminate the surface roughness on the raceways of the bearing rings resulting from the deposition of the polymer layer and its subsequent heat treatment, the operation of rolling these surfaces under load is carried out. This operation can be carried out both separately on the rings in a special technological installation, and by rolling the bearing assembly for 5 120 minutes. In the absence of requirements for the vibro-acoustic characteristics of the bearing, the rolling operation may not be necessary. The proposed rolling bearing with a constant lubricating layer is characterized by the presence of an additional lubricating layer in the form of a thin film held on the surfaces of the polymer layer deposited on the raceways of the bearing rings and the windows of its metal cage. This additional lubricant layer is formed due to the compatibility of the lubricant impregnating the polymer layer with the working lubricant of the bearing. The compatibility of lubricants is ensured by the fulfillment of conditions (1) and (2) based on the data in Table 1. The choice of impregnating lubricant according to the conditions of bearing loading is carried out in compliance with conditions (3) based on the data on the nomogram of figure 5. In addition, the compatibility of intermixed lubricants should be taken into account by comparing their base thickeners based on the data in Table 1. The kinematic viscosity of a constant lubricating layer for the analysis of operation and bearing calculations can be determined by equation (4). In this case, the kinematic viscosity of the polymer layer deposited by the indicated technology is in the range of 4700 4800 mm ² / s.

Example 1. A spindle bearing 2-36202K was made with a constant lubricating layer on the raceways of the outer and inner rings, and the cage was made of textolite. An emulsion of styrene-acrylate copolymers of type N 4696 was used as the material to be deposited, which was applied by the method of electrodeposition on the annular raceways of the bearing rings, followed by washing and heat treatment in compliance with all the regimes recommended in the materials of this application. The thickness of the polymer layer was 1.2 μm. The polymer layer on the rings was impregnated with a lubricant selected according to the technology specified in the application. A Russian-made lubricant of the LKS-2 type was used, which is recommended for low-noise, high-speed bearings, such as a spindle bearing. Lubricant selected compatible with I-20 bearing industrial oil (industrial). Tests of this bearing were carried out by installing it on the electrospindle of the EShV-28 / 2.8 machine, which had an angular velocity of 24,000 min ^-1 . An indicator of durability was the level of vibration. The rolling operation of the polymer layer was carried out directly in the installation site for 15 minutes During operation of the bearing with a constant lubricating layer, the vibration level was measured, which was compared with the vibration level of the bearing without a constant lubricating layer. The test results are presented in Fig.6. From this diagram it can be seen that the bearing under study has better characteristics compared to a standard bearing. At the same time, the improvement in the characteristics of the vibration level increased in time and the durability of the bearing with a constant lubricating layer was more than 3 times higher than the durability of a serial bearing.

 Example 2. For the HSA-187 spindle of a Korean engineering company (KMS R8D Center), bearings 2-436107K were made with and without a constant additional lubricating layer. Only the raceways of the bearing rings, which were impregnated with grease, were coated with a polymer layer. The separators were made of PCB. The technology for producing the lubricating layer on the rings was carried out in accordance with the modes of applying the polymer layer, introducing the lubricant and their corresponding heat treatments indicated in the invention. Coating thickness 0.5 μm. Arcanol-L-138 (Arcanol L-138), created specifically for bearings, which are subject to particularly high demands on noise and high rotation speeds, was chosen as the introduced lubricant. This grease has been selected to be compatible with bearing lubrication with industrial oil. The rolling was carried out for 30 minutes at a stand in Russia. Bearing tests were carried out in the Republic of Korea on HSA-187 spindles at a load of 20 kgf at a rotation speed of 20,000 rpm. The test results are shown in table.3. It can be seen from this table that bearings with a constant lubricating layer exceeded the resource without bearings by such a layer by more than 4 times and had a lower level of vibration.

Example 3. The Korean company KMS R8D Center manufactured for comparative tests tapered bearings TR 285216g. These bearings worked at sufficiently high loads P _o 250 kgf / mm ² . In addition, during the tests, they were subject to increased requirements for durability, friction, run-out and vibration. The creation of a permanent lubricating layer was carried out both on the rings and on the metal bearing cages according to the technology specified in the application in Russia, but no roughness was rolled. Layer thickness 1.0 μm on rings and 12 μm on separators. Arcanol L-78 (Arcanol L-78) grease for heavily loaded bearings, but also suitable for low noise bearings, was chosen as an impregnating lubricant under compatibility conditions. It was compatible with lithium-based bearing grease. The test results are given in table. 4 and 5. From these tables it can be seen that after 200 hours of operation, the characteristics of bearings with a constant lubricating layer of TR 285216g are much better compared to bearings without it. However, at the initial moment of testing, indicators such as run-out and vibration level of bearings with a constant lubricating layer were slightly worse, which indicates the advisability of introducing rolling operations for them in the technological process.

Claims (6)

 1. Bearing with a constant lubricating layer, consisting of an outer ring provided with an inwardly facing annular raceway, and an inner ring provided with an outwardly facing annular raceway, between which rolling elements are located located at a certain distance from each other by means of a separator, while working the surfaces of these parts of the bearing are coated with a polymer layer, characterized in that the polymer layer is made of anode electrodeposited material such as styrene-acrylate copolymer s and impregnated with lubricant, compatible with the working of the bearing lubricant, selected according to the conditions of operation of the bearing and to provide a polymer layer on the surface of an additional layer of lubricant as a thin film. 2. The bearing according to claim 1, characterized in that the compatibility of these lubricants is ensured by their mutual selection based on the compatibility of the base thickeners of these lubricants, while the rolling friction coefficient of the resulting lubricant mixture is determined in the range 0 <f <0.05, where f is the friction coefficient rolling, when testing this mixture for at least 2 hours, and its penetration is determined within the limits P _max >P> P _min , where P _max , P _{min are the} limiting values of the penetration of the specified mixed lubricants. 3. The bearing according to claim 1 or 2, characterized in that the lubricant impregnating the polymer layer is selected taking into account the load of the bearing and the kinematic viscosity of the constant lubricating layer, based on the condition

where γ ₁ is the reference kinematic viscosity to ensure normal lubricity of the bearing, taking into account its load and operating conditions during operation, γ _{cc is the} kinematic viscosity of the constant lubricating layer, determined by the formula

where γ _p is the kinematic viscosity of the polymer layer;
γ _cm - kinematic viscosity of the lubricant impregnating the polymer layer;

the fill factor of the polymer layer with grease;
V _{cm is the} volume of lubricant embedded in the polymer layer;
V _{p the} volume of the deposited polymer layer.  4. The bearing according to claim 1, or 2, or 3, characterized in that the thickness of the polymer layer on the raceways of the outer and inner rings is 0.3 to 3.0 μm.  5. The bearing according to claim 1, or 2, or 3, characterized in that the thickness of the additional lubricating layer is 0.5 to 5.0 microns. 6. A method of manufacturing a bearing with a constant lubricating layer, namely, that the bearing parts are placed in an aqueous solution containing an emulsion of styrene-acrylate copolymers in an amount of 1.8 to 8.0 wt. and by anodic electrodeposition, a polymer layer is applied to the working surfaces of the bearing, then the parts are washed and heat treated, characterized in that the electrodeposition is carried out for 3 300 s, heat treatment is carried out for 1 10 min, obtained from the operating conditions of the bearing, then the bearing parts are subjected to secondary heat treatment at 80 150 ^o C for 10 60 minutes, and carry out the rolling of the working surfaces of the bearing parts for 5 120 minutes

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