A method for determining the critical speed of a water-lubricated bearing injected with a second lubricating medium

Abstract

The present invention relates to a method for determining the critical speed of a water-lubricated bearing injected with a second lubricant medium, comprising the following steps: using pure water as the lubricant to measure the first Stribeck curve of the current water-lubricated bearing; using an oily second lubricant medium as the lubricant to measure the second Stribeck curve of the current water-lubricated bearing; combining the first Stribeck curve and the second Stribeck curve to synthesize a third Stribeck curve, defining the third Stribeck curve as the function C = f(S), where S is the third bearing characteristic coefficient ηv / W, where η is the comprehensive viscosity after injecting the second lubricant medium, and η has the following relationship with the supply amount q of the second lubricant medium: η = kq<supgt;R< / supgt>; given the load W of the water-lubricated bearing and the supply amount q of the second lubricant medium, determining the speed at which the friction coefficients under pure water lubrication conditions and under lubrication conditions after injecting the second lubricant medium with a supply amount of q are equal according to the third Stribeck curve, and determining this speed as the critical speed.

Description

Technical Field

[0001] The present invention relates to a method for determining the critical speed of a water-lubricated bearing injecting a second lubricant medium, and belongs to the technical field of water-lubricated bearing regulation and control. Background Art

[0002] Water is used instead of lubricating oil in water-lubricated bearings, which has the advantages of no pollution, good heat dissipation effect and simple structure, and has been widely used in marine equipment such as ships and warships. However, due to the low viscosity and low film-forming ability of water, the load-carrying capacity of water-lubricated bearings and their stability under harsh working conditions are poor.

[0003] To improve the load-carrying capacity of water-lubricated bearings, many studies have been carried out on the structure and materials of water-lubricated bearings, which have improved the tribological performance of the bearings to a certain extent. For example, Chinese Patent CN202120581673.6 discloses a spiral rubber bearing, in which a number of spiral water grooves are arranged at intervals along the inner circumference of the rubber bushing body. Through the setting of the first fillet between the bottom of the spiral water groove and the rubber body, the friction force in the spiral water groove is reduced, the retention probability of fine sand in water lubrication is reduced, and the service life of the spiral rubber bearing is prolonged. Chinese Patent CN202110537740.9 discloses a water-lubricated bearing composite material and its preparation method, in which PU and EP are simultaneously introduced into the NBR material, greatly improving the elasticity, damping shock absorption and anti-friction and wear resistance of the material. Although the above technologies can improve the load-carrying capacity of water-lubricated bearings to a certain extent, they do not get rid of the disadvantages of water as a single lubricant medium. When encountering harsh working conditions such as low speed and heavy load, the water film cannot provide good lubrication for the bearing.

[0004] Regarding the problems existing in the above-mentioned prior art, Patent ZL202010840358.0 proposes a solution of using oil as a trace second lubricant medium to assist water lubrication, which can better improve the lubrication effect of water-lubricated bearings and take environmental protection into account. In this solution, when a trace amount of oil enters the contact area as the second lubricant medium to participate in lubrication, the wear can be reduced.

[0005] However, at different speeds, the friction coefficient will change differently. Experiments have proved that there is a critical speed at which the friction coefficient of the water-lubricated bearing does not change significantly after injecting a trace amount of lubricating oil. When the speed of the water-lubricated bearing is lower / higher than the critical speed, the friction coefficient decreases / increases. In the actual operation of the water-lubricated bearing, the supply amount or viscosity of the trace second lubricant medium should be controlled so that its critical speed is greater than its operating speed to obtain a lower friction coefficient and less wear. Therefore, there is an urgent need to design a method for finding and regulating the critical speed. Summary of the Invention

[0006] To solve the problems existing in the above-mentioned prior art, the present invention proposes a method for determining the critical speed of a water-lubricated bearing into which a second lubricant medium is injected. By measuring the first Stribeck curve of the water-lubricated bearing in the pure water lubrication state and the second Stribeck curve in the second lubricant medium lubrication state, and combining the first Stribeck curve and the second Stribeck curve to generate a third Stribeck curve, based on the third Stribeck curve, for different supply amounts of the second lubricant medium and different loads, the value of the critical speed can be quickly determined.

[0007] The technical solution of the present invention is as follows:

[0008] On the one hand, the present invention proposes a method for determining the critical speed of a water-lubricated bearing into which a second lubricant medium is injected, including the following steps:

[0009] Using pure water as the lubricant of the water-lubricated bearing, measure the first Stribeck curve of the current water-lubricated bearing body. The ordinate of the first Stribeck curve is the coefficient of friction cof, and the abscissa is the first bearing characteristic coefficient η0v / W, where η0 is the viscosity of pure water, v is the sliding speed, and W is the load;

[0010] Using an oily second lubricant medium as the lubricant of the water-lubricated bearing, measure the second Stribeck curve of the current water-lubricated bearing body. The ordinate of the second Stribeck curve is the coefficient of friction cof, and the abscissa is the second bearing characteristic coefficient η Δ v / W, where η Δ is the viscosity of the second lubricant medium;

[0011] Combine the first Stribeck curve and the second Stribeck curve to synthesize a third Stribeck curve, and define the third Stribeck curve as the function C = f(S), where C is the coefficient of friction cof, and S is the third bearing characteristic coefficient ηv / W, where η is the comprehensive viscosity of the load-bearing area of the water-lubricated bearing after injecting the second lubricant medium, and η has the following relationship with the supply amount q of the second lubricant medium η = kq R , where k is a coefficient dependent on the water-lubricated bearing system and the viscosity of the second lubricant medium, and R is the supply amount index coefficient;

[0012] Given the load W of the water-lubricated bearing and the supply amount q of the second lubricant medium, determine the speed at which the coefficient of friction of the lubrication state point when the lubricant is pure water is equal to the coefficient of friction of the lubrication state point after injecting the second lubricant medium with a supply amount of q according to the third Stribeck curve, and determine this speed as the critical speed.

[0013] Preferably, the method for synthesizing the third Stribeck curve by combining the first Stribeck curve and the second Stribeck curve is specifically as follows:

[0014] Take the friction coefficient cof of the ordinate in the first Stribeck curve and the second Stribeck curve as the ordinate of the third Stribeck curve;

[0015] Calculate the third bearing characteristic coefficient for the viscosity, speed, and load corresponding to each measurement point in the first Stribeck curve and the second Stribeck curve, and finally use the calculated result as the abscissa of the third Stribeck curve to form the third Stribeck curve.

[0016] Preferably, the method for determining the rotational speed at which the friction coefficients of the lubrication state point when the lubricant is pure water and the lubrication state point after injecting the second lubricant with a supply amount of q are equal according to the third Stribeck curve is specifically as follows:

[0017] Respectively fit the mixed lubrication part and the elastohydrodynamic lubrication part in the third Stribeck curve with linear functions to obtain the first linear curve y1 = k1x + b1 and the second linear curve y2 = k2x + b2;

[0018] Substitute the load W into the first linear curve and the second linear curve respectively. At the same time, determine the comprehensive viscosity η of the water-lubricated bearing load-bearing area after injecting the second lubricant according to the supply amount q. Substitute the viscosity η0 of pure water into the first linear curve, and substitute the comprehensive viscosity η of the water-lubricated bearing load-bearing area into the second linear curve to obtain

[0019] Let y1 = y2 and solve for v x which is the critical rotational speed.

[0020] On the other hand, the present invention also provides a system for determining the critical rotational speed of a water-lubricated bearing injecting a second lubricant, including: a pure water Stribeck curve measurement unit, a second lubricant Stribeck curve measurement unit, a Stribeck curve synthesis unit, and a critical rotational speed determination unit;

[0021] The pure water Stribeck curve measurement unit is used to measure the first Stribeck curve of the current water-lubricated bearing body with pure water as the lubricant of the water-lubricated bearing. The ordinate of the first Stribeck curve is the friction coefficient cof, and the abscissa is the first bearing characteristic coefficient η0v / W, where η0 is the viscosity of pure water, v is the sliding speed, and W is the load;

[0022] The second lubricant medium Stribeck curve measurement unit is used to measure the second Stribeck curve of the current water-lubricated bearing body with an oily second lubricant medium as the lubricant for the water-lubricated bearing. The ordinate of the second Stribeck curve is the coefficient of friction cof, and the abscissa is the second bearing characteristic coefficient η Δ v / W, where η Δ is the viscosity of the second lubricant medium;

[0023] The Stribeck curve synthesis unit is used to synthesize a third Stribeck curve by combining the first Stribeck curve and the second Stribeck curve, and defines the third Stribeck curve as the function C = f(S), where C is the coefficient of friction cof, and S is the third bearing characteristic coefficient ηv / W, where η is the comprehensive viscosity of the load-bearing area of the water-lubricated bearing after injecting the second lubricant medium. There is the following relationship between η and the supply quantity q of the second lubricant medium: η = kq R , where k is a coefficient dependent on the water-lubricated bearing system and the viscosity of the second lubricant medium, and R is the supply quantity index coefficient;

[0024] The critical speed determination unit is used to obtain the load W of a given water-lubricated bearing and the supply quantity q of the second lubricant medium, and determine the speed at which the coefficient of friction of the lubrication state point when the lubricant is pure water is equal to the coefficient of friction of the lubrication state point after injecting the second lubricant medium with the supply quantity q according to the third Stribeck curve, and determine this speed as the critical speed.

[0025] Preferably, the method for the Stribeck curve synthesis unit to synthesize the third Stribeck curve is specifically as follows:

[0026] Take the coefficient of friction cof of the ordinate in the first Stribeck curve and the second Stribeck curve as the ordinate of the third Stribeck curve;

[0027] Calculate the third bearing characteristic coefficient from the viscosity, speed, and load corresponding to each measurement point in the first Stribeck curve and the second Stribeck curve, and finally take the calculated result as the abscissa of the third Stribeck curve to form the third Stribeck curve.

[0028] Preferably, the method for the critical speed determination unit to determine the speed at which the coefficient of friction of the lubrication state point when the lubricant is pure water is equal to the coefficient of friction of the lubrication state point after injecting the second lubricant medium with the supply quantity q according to the third Stribeck curve is specifically as follows:

[0029] The mixed lubrication part and the elastohydrodynamic lubrication part in the third Stribeck curve are respectively fitted by linear functions to obtain the first linear curve y1 = k1x + b1 and the second linear curve y2 = k2x + b2;

[0030] The load W is respectively substituted into the first linear curve and the second linear curve. At the same time, according to the supply quantity q, the comprehensive viscosity η of the water-lubricated bearing load-bearing area after injecting the second lubricant is determined. The viscosity η0 of pure water is substituted into the first linear curve, and the comprehensive viscosity η of the water-lubricated bearing load-bearing area is substituted into the second linear curve, and we get

[0031] Let y1 = y2, and solve for v x which is the critical speed.

[0032] On the other hand, the present invention also provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, it implements the method for determining the critical speed of a water-lubricated bearing injecting a second lubricant as described in any embodiment of the present invention.

[0033] On the other hand, the present invention also provides a computer-readable storage medium, on which a computer program is stored. When the program is executed by a processor, it implements the method for determining the critical speed of a water-lubricated bearing injecting a second lubricant as described in any embodiment of the present invention.

[0034] On the other hand, the present invention also provides a method for regulating the critical speed of a water-lubricated bearing injecting a second lubricant, including the following steps:

[0035] Based on the method for determining the critical speed of a water-lubricated bearing injecting a second lubricant as described in any embodiment of the present invention, determine the relationship between the critical speed of the water-lubricated bearing and the load W and the supply quantity q of the second lubricant;

[0036] According to the relationship between the critical speed of the water-lubricated bearing and the load W and the supply quantity q of the second lubricant, adjust the load W or the supply quantity q of the second lubricant to regulate the critical speed of the water-lubricated bearing.

[0037] The present invention has the following beneficial effects:

[0038] 1. For the method of determining the critical speed of a water-lubricated bearing injecting a second lubricant in the present invention, by measuring the first Stribeck curve in the pure water lubrication state and the second Stribeck curve in the second lubricant lubrication state of the water-lubricated bearing, and combining the first Stribeck curve and the second Stribeck curve to generate a third Stribeck curve, based on the third Stribeck curve, for different supply quantities of the second lubricant and different loads, the value of the critical speed can be quickly determined.

[0039] 2. A method for regulating the critical speed of a water-lubricated bearing injecting a second lubricant medium determines the relationship between the critical speed of the water-lubricated bearing, the load W, and the supply amount q of the second lubricant medium, and regulates the critical speed based on this relationship to achieve the purpose of improving the lubrication effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a flowchart of the method for determining the critical speed of a water-lubricated bearing injecting a second lubricant medium in an embodiment of the present invention;

[0041] Figure 2 It is an exemplary diagram of the third Stribeck curve in an embodiment of the present invention;

[0042] Figure 3 It is an exemplary diagram of fitting the third Stribeck curve by a linear function in an embodiment of the present invention;

[0043] Figure 4 It is a graph showing the change of the friction coefficient of a bearing with the rotation speed under pure water lubrication conditions in an embodiment of the present invention;

[0044] Figure 5 It is a graph showing the change of the friction coefficient of a bearing with the rotation speed under the lubrication condition of the second lubricant medium in an embodiment of the present invention;

[0045] Figure 6 It is a schematic diagram of the third Stribeck curve generated by the Stribeck curve synthesis unit in an embodiment of the present invention;

[0046] Figure 7 、 Figure 8 and Figure 9 They are respectively graphs showing the change of the friction coefficient before and after injecting the second lubricant medium at different rotation speeds in an embodiment of the present invention;

[0047] Figure 10 It is a flowchart of the method for regulating the critical speed of a water-lubricated bearing injecting a second lubricant medium in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0048] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts belong to the scope of protection of the present invention.

[0049] It should be understood that the step numbers used in the text are only for convenient description and do not limit the execution order of the steps.

[0050] It should be understood that the terms used in the specification of the present invention are merely for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include the plural forms.

[0051] The terms "comprising" and "including" indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or their combinations.

[0052] The term "and / or" refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0053] See Figure 1 , an embodiment of the present application provides a method for determining the critical speed of a water-lubricated bearing injecting a second lubricant medium, including the following steps:

[0054] S101. Using pure water as the lubricant of the water-lubricated bearing, measure the first Stribeck curve of the current water-lubricated bearing body. The ordinate of the first Stribeck curve is the coefficient of friction cof, and the abscissa is the first bearing characteristic coefficient (η0v / W), where η0 is the viscosity of pure water, v is the sliding speed, and W is the load.

[0055] S102. Using an oily second lubricant medium as the lubricant of the water-lubricated bearing, measure the second Stribeck curve of the current water-lubricated bearing body. The ordinate of the second Stribeck curve is the coefficient of friction cof, and the abscissa is the second bearing characteristic coefficient (η Δ v / W), where η Δ is the viscosity of the second lubricant medium; it should be noted that the second lubricant medium is generally mineral oil, synthetic oil, emulsified oil, vegetable oil, animal oil, etc., so the viscosity η Δ of the second lubricant medium >> η0.

[0056] On the Stribeck curve, the first Stribeck curve of pure water is mainly concentrated in a part of the mixed lubrication state and the elastohydrodynamic lubrication state, while the second Stribeck curve of the second lubricant medium is more concentrated in the elastohydrodynamic lubrication state and the hydrodynamic lubrication state.

[0057] S103. Combine the first Stribeck curve measured in step S101 and the second Stribeck curve measured in step S102 to synthesize a third Stribeck curve, and define the third Stribeck curve as the function C = f(S), where C is the coefficient of friction cof and S is the third bearing characteristic coefficient (ηv / W), where η is the comprehensive viscosity of the water-lubricated bearing load-bearing area after injecting the second lubricant medium. In this function, each bearing characteristic coefficient S corresponds to a known coefficient of friction C; it is set that η and the supply quantity q of the second lubricant medium have the following relationship η = kq R , where k is a coefficient dependent on the water-lubricated bearing system and the viscosity of the second lubricant medium and can be set as a fixed value, R is the supply quantity exponential coefficient, and the synthesized third Stribeck curve is as Figure 2 shown.

[0058] S104. Given the working conditions, obtain the load W of the water-lubricated bearing under these working conditions and the supply quantity q of the second lubricant medium. According to the third Stribeck curve, determine the rotational speed at which the coefficient of friction of the lubrication state point when the lubricant is pure water is equal to the coefficient of friction of the lubrication state point after injecting the second lubricant medium with the supply quantity q, and determine this rotational speed as the critical rotational speed.

[0059] As Figure 2 shown, Figure 2 in it, point A is the lubrication state point when the rotational speed is v1, the load is W1, and the lubricant is pure water, denoted as S 01 = η0v1 / W1, η0 is the viscosity of water, and the corresponding coefficient of friction Point B is the lubrication state point after injecting the oil quantity q1 at point A, denoted as S 11 = η1v1 / W1, η1 is the comprehensive viscosity corresponding to the supply quantity q1, and the corresponding coefficient of friction It can be seen from the figure that then it shows that v1 is the critical rotational speed for the supply quantity q1 and the load W1. Conversely, it is not its critical rotational speed. In Figure 2 in it, point E is the lubrication state point when the rotational speed is v2, the load is W2, and the lubricant is pure water, denoted as S 02 , point F is the lubrication state point after injecting the oil quantity q2 at point E, denoted as S 22 , it can be seen that the coefficient of friction when it is pure water is greater than the coefficient of friction after injecting the second lubricant medium. From this, it can be deduced that the critical rotational speed v for the supply quantity q2 and the load W2 is greater than v2. Similarly, it can be obtained that if the coefficient of friction when it is pure water is less than the coefficient of friction after injecting the second lubricant medium, such as points C and D, denoted as S 03 and S 33 respectively, then its critical rotational speed is less than the actual rotational speed. Therefore, for a certain supply quantity q x and load W x , the critical rotational speed is vC , v x is the actual rotational speed, and we can obtain:

[0060]

[0061] where η x is the comprehensive viscosity of the injection supply quantity q x .

[0062] Using the above method, it is possible to quickly determine whether the input rotational speed is the critical rotational speed corresponding to a certain definite working condition, and the range of the critical rotational speed can be determined by using the bisection method.

[0063] In an embodiment of the present application, in step S103, the method of synthesizing the third Stribeck curve by combining the first Stribeck curve and the second Stribeck curve is specifically as follows:

[0064] Take the friction coefficient cof of the ordinate in the first Stribeck curve and the second Stribeck curve as the ordinate of the third Stribeck curve;

[0065] Calculate the third bearing characteristic coefficient based on the viscosity, speed, and load corresponding to each measurement point in the first Stribeck curve and the second Stribeck curve, and finally take the calculated result as the abscissa of the third Stribeck curve to form the third Stribeck curve.

[0066] In an embodiment of the present application, in step S104, the method of determining the rotational speed at which the friction coefficients of the lubrication state point when the lubricant is pure water and the lubrication state point after injecting the second lubricating medium with the injection supply quantity of q are equal according to the third Stribeck curve is specifically as follows:

[0067] Solve using the graphical method. First, respectively fit the mixed lubrication part and the elastohydrodynamic lubrication part in the third Stribeck curve obtained in step S103 through a linear function, as Figure 3 shown, to obtain the first linear curve as y1 = k1x + b1 and the second linear curve as y2 = k2x + b2; where k1, b1, k2, and b2 are all known constants obtained according to the fitting results;

[0068] Figure 3 In, point A is the lubrication state point when the rotational speed is v1, the load is W, and the lubricant is pure water, denoted as S 01 = η0v1 / W, where η0 is the viscosity of water; point B is the lubrication state point after injecting the oil quantity q1 at point A, denoted as S 11= η1v1 / W, where η1 is the viscosity corresponding to the supply quantity q1; it can be seen from the figure that the friction coefficients corresponding to points A and B are equal, so the rotational speed v1 is the critical rotational speed corresponding to the supply quantity q1. If the supply quantity at point A is q2 (q2 > q1) and the comprehensive viscosity of the lubricating medium in the contact area is η2, and here it is considered that η2 > η1, then the end point of the lubrication state transition corresponding to the supply quantity q2, load W, and rotational speed v1 will move from point B to point C, denoted as S 21 = η2v1 / W; because it can be seen from the figure that the friction coefficient at point C is greater than that at point A, and from step 104, it can be known that the rotational speed v1 is not the critical rotational speed corresponding to the supply quantity q2. If the critical rotational speed v2 corresponding to the supply quantity q2 is to be found, it is necessary to make the starting point and the ending point of the corresponding bearing characteristic coefficient change fall on the Stribeck curve and the friction coefficients of the two points are equal. It is necessary to move points C and A to the left on the Stribeck curve to the corresponding points D and E. Here, the bearing characteristic coefficient corresponding to point E 02 = η0v2 / W, and the bearing characteristic coefficient corresponding to point D 22 = η2v2 / W. At this time, in order to find the critical rotational speed v2 corresponding to the supply quantity q2, it is necessary to use the relationship that the ordinates of points E and D are equal, that is, substitute the abscissas of points E and D into curve 1 and curve 2 respectively, denoted as and

[0069] And make the two equations equal It can be obtained that where b1, b2, W, k1, k2, η0, and η2 are all known quantities, from which the value of the critical rotational speed v2 can be determined, and the positions of points E and D on the two linear curves can also be determined.

[0070] The embodiment of the present application also provides a system for determining the critical rotational speed of a water-lubricated bearing injecting a second lubricating medium, including: a pure water Stribeck curve measuring unit, a second lubricating medium Stribeck curve measuring unit, a Stribeck curve synthesizing unit, and a critical rotational speed determining unit;

[0071] The pure water Stribeck curve measuring unit is used to measure the first Stribeck curve of the current water-lubricated bearing body with pure water as the lubricant of the water-lubricated bearing;

[0072] In this embodiment, the pure water Stribeck curve measurement unit uses a ring-on-block tester to measure the curve of the friction coefficient varying with the rotational speed under pure water lubrication conditions; specifically: using common water-lubricated material nitrile rubber as the counter-block, with a surface roughness of 0.4; using 316 stainless steel as the counter-ring, with a surface roughness of 0.3; using tap water as the lubricating medium to immerse the friction pair, setting the load of the friction pair to 50 N, measuring the friction coefficient between the friction pairs under pure water lubrication conditions at different rotational speeds, with the rotational speed range from 50 r / min to 2000 r / min, and maintaining each rotational speed for 60 s, the measurement results are as Figure 4 shown. It can be seen from Figure 4 that the friction coefficient between the friction pairs under pure water lubrication continuously decreases with the increase of the rotational speed, being in the descending section of the classical Stribeck curve, that is, in the mixed lubrication state or the elastohydrodynamic lubrication state. Calculate the first bearing coefficient (η0v / W) corresponding to each rotational speed, with the first bearing coefficient (η0v / W) as the abscissa and the friction coefficient cof as the ordinate, to obtain the first Stribeck curve.

[0073] The second lubricant Stribeck curve measurement unit is used to use an oily second lubricant as the lubricant for the water-lubricated bearing, and measure the second Stribeck curve of the current water-lubricated bearing body;

[0074] In this embodiment, a ring-on-block tester is used to measure the curve of the friction coefficient of the second lubricant varying with the rotational speed; the second lubricant is generally mineral oil, synthetic oil, emulsified oil, vegetable oil, animal oil, etc., and different second lubricants can be selected according to different bearing materials and working conditions. In this embodiment, taking emulsified oil as an example, measure the curve of the friction coefficient of the friction pair varying with the rotational speed of the steel ring, specifically as Figure 5 shown. The specific measurement method and materials, etc. are the same as those for measuring the change curve under pure water lubrication conditions above, and the measurement results are as Figure 5 shown. Calculate the second bearing coefficient (η Δ v / W) corresponding to each rotational speed, with the first bearing coefficient (η Δ v / W) as the abscissa and the friction coefficient cof as the ordinate, to obtain the second Stribeck curve.

[0075] The Stribeck curve synthesis unit is used to combine the first Stribeck curve and the second Stribeck curve to synthesize the third Stribeck curve, and the generated third Stribeck curve is as Figure 6As shown in the figure; the specific synthesis method is as follows: First, take the ordinate (cof) in the first Stribeck curve and the second Stribeck curve as the ordinate of the third Stribeck curve. Secondly, calculate the viscosity η, linear velocity u, and load P corresponding to each point in the first Stribeck curve and the second Stribeck curve according to the formula for calculation. Finally, take the calculation result as the abscissa of the third Stribeck curve to form the third Stribeck curve.

[0076] The critical speed determination unit is used to obtain the load W of a given water-lubricated bearing and the supply amount q of the second lubricant, and determine the speed at which the friction coefficient of the lubrication state point when the lubricant is pure water is equal to the friction coefficient of the lubrication state point after injecting the second lubricant with a supply amount of q according to the third Stribeck curve, and determine this speed as the critical speed.

[0077] To verify the accuracy of the determined critical speed, in this embodiment, a ring-block testing machine is used to measure the change curve of the friction coefficient of the ring-block friction pair with time before and after injecting the second lubricant. Still select nitrile rubber as the counter block and 316 stainless steel as the counter ring. The experimental load is 50 N, and the change curves of the friction coefficient before and after injecting the second lubricant (50 μL) at 3 different speeds. As Figure 6 shown in FIGS. 7 / 8 / 9, the front half of the curve segment in the figure represents the change of the friction coefficient under pure water lubrication conditions, and the latter half of the curve segment is the change of the friction coefficient after injecting the second lubricant into the contact area under pure water lubrication conditions; Figure 7 、 Figure 8 and Figure 9 are the friction coefficient change curves at speeds of 100 r / min, 175 r / min, and 200 r / min respectively. It can be found that at a speed of 175 r / min, the friction coefficients before and after injecting the second lubricant are basically equal (the error is within 5%), that is, the critical speed under the conditions of a supply amount of 50 μL and a load of 50 N is considered to be 175 r / min. Figure 7 、 Figure 8 and Figure 9 correspond to Figure 2 the EF segment, AB segment, and CD segment in

[0078] In this embodiment, the third Stribeck curve has been obtained. The curve is mainly composed of a descending segment and an ascending segment. Therefore, the third Stribeck curve is simplified into a curve composed of two linear functions, namely the first linear curve and the second linear curve. Since the third Stribeck curve is measured by experiment, the points on the curve are all known quantities. Two points (0.00223, 0.07485) and (0.11886, 0.02722) are selected in the descending segment and substituted into the first linear curve y1=k1x+b1, and k1=-1.14265 and b1=0.07740 are obtained. Similarly, two points (0.832, 0.018959) and (1.30743, 0.02296) are selected in the ascending segment and substituted into the second linear curve y2=k2x+b2, and k2=0.00842 and b2=-0.08704 are obtained. The comprehensive viscosity and the supply amount q satisfy η=kq R , where k is a coefficient that depends on the viscosity of the system and the second lubricant, which can be taken as 0.8 here, and R is the supply index coefficient. Taking the supply of 50μL and the load of 350N as an example, calculate the critical speed v under this condition; first determine the lubrication state point of pure water under the conditions of load 350N and speed v, that is, S=η0v / W=1*v / 350, and substitute x=v / 350 into the first linear curve y1=k1x+b1 to obtain, Secondly, determine the lubrication state point after injecting 50μL of oil, S=η 50 v / W=200*v / 350, substitute x=4v / 7 into the second linear curve y2=k1x+b1, and we get y2=0.00481v-0.08704; the two equations are equal, and we get the critical speed v=0.455m / s under the conditions of supply volume 50μL and load 350N. Therefore, within the specified load and supply range, we only need to determine the load and supply to determine the critical speed corresponding to any load and supply.

[0079] The emulsified oil involved in this embodiment is a commercially available environmentally friendly metal cutting fluid.

[0080] The viscosity of the emulsified oil involved in this embodiment is greatly affected by the temperature of the ring-block friction pair, so the viscosity value used in the calculation is the viscosity value at a certain temperature.

[0081] See also Figure 10 The present application also provides a method for regulating the critical speed of a water-lubricated bearing injected with a second lubricating medium, comprising the following steps:

[0082] S201, determining the relationship between the critical speed of the water-lubricated bearing and the load W and the second lubricating medium supply amount q based on the method for determining the critical speed of the water-lubricated bearing injected with the second lubricating medium according to any embodiment of the present invention;

[0083] S202. As can be seen from the above embodiments, the critical speed Among them, b1, b2, k1, k2, η0, and η2 are fixed values. Therefore, as the load increases, the critical speed increases, and as the supply decreases, the critical speed increases. The higher the critical speed, the larger the speed range in which the friction coefficient can be reduced. Therefore, in actual operation, the critical speed should be increased by adjusting the supply and the load to achieve the effect of reducing friction.

[0084] Moreover, after determining the supply q, load W, and speed v of the water-lubricated bearing, when determining the value of its critical speed, the friction coefficient can be reduced by reducing the speed to a certain extent. Therefore, a joint control system for the supply q, load W, and speed v can be established, and the values of the three parameters can be flexibly adjusted according to the actual situation to enable the water-lubricated bearing to achieve the best lubrication effect.

[0085] The embodiment of the present application also provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, it implements the method for determining the critical speed of the water-lubricated bearing injecting the second lubricating medium as described in any embodiment of the present invention.

[0086] The embodiment of the present application also provides a computer-readable storage medium, on which a computer program is stored. When the program is executed by a processor, it implements the method for determining the critical speed of the water-lubricated bearing injecting the second lubricating medium as described in any embodiment of the present invention.

[0087] Those of ordinary skill in the art can realize that the units and algorithm steps described in the embodiments disclosed herein can be implemented by a combination of electronic hardware, computer software, and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present application.

[0088] Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the systems, devices, and units described above can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein.

[0089] In several embodiments provided by the present application, if any function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present application. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, read-only memories (ROM), random access memories (RAM), magnetic disks, or optical discs.

[0090] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A method for determining the critical speed of a water-lubricated bearing injected with a second lubricating medium, characterized in that It includes the following steps: Using pure water as the lubricant for the water-lubricated bearing, measure the first Stribeck curve of the current water-lubricated bearing body. The ordinate of the first Stribeck curve is the coefficient of friction cof, and the abscissa is the first bearing characteristic coefficient η0v / W, where η0 is the viscosity of pure water, v is the sliding speed, and W is the load; Using an oily second lubricating medium as the lubricant for a water-lubricated bearing, measure the second Stribeck curve of the current water-lubricated bearing body. The ordinate of the second Stribeck curve is the coefficient of friction cof, and the abscissa is the second bearing characteristic coefficient η Δ v / W, where η Δ is the viscosity of the second lubricating medium; Combining the first Stribeck curve and the second Stribeck curve to synthesize a third Stribeck curve, defining the third Stribeck curve as the function C = f(S), where C is the coefficient of friction cof, S is the third bearing characteristic coefficient ηv / W, where η is the comprehensive viscosity of the load-bearing area of the water-lubricated bearing after injecting the second lubricant, and there is the following relationship between η and the supply quantity q of the second lubricant: η = kq R , where k is a coefficient dependent on the water-lubricated bearing system and the viscosity of the second lubricant, and R is the supply quantity index coefficient; Given the load W of the water-lubricated bearing and the supply amount q of the second lubricant medium, determine the rotational speed at which the coefficient of friction at the lubrication state point when the lubricant is pure water is equal to the coefficient of friction at the lubrication state point after injecting the second lubricant medium with a supply amount of q according to the third Stribeck curve, and determine this rotational speed as the critical speed.

2. The method for determining the critical speed of a water-lubricated bearing injecting a second lubricating medium according to claim 1, wherein The method of synthesizing the third Stribeck curve by combining the first Stribeck curve and the second Stribeck curve is specifically as follows: Join the first Stribeck curve and the second Stribeck curve together. Use the first Stribeck curve as the mixed lubrication part and the second Stribeck curve as the elastohydrodynamic lubrication part to form the third Stribeck curve; Use the coefficient of friction cof in the ordinate of the first Stribeck curve and the second Stribeck curve as the ordinate of the third Stribeck curve; Calculate the third bearing characteristic coefficient for the viscosity, speed, and load corresponding to each measurement point in the first Stribeck curve and the second Stribeck curve, and finally use the calculated results as the abscissa of the third Stribeck curve to form the third Stribeck curve.

3. A method for determining the critical speed of a water-lubricated bearing injecting a second lubricating medium according to claim 2, wherein The method of determining the rotational speed at which the coefficient of friction at the lubrication state point when the lubricant is pure water is equal to the coefficient of friction at the lubrication state point after injecting the second lubricant medium with a supply amount of q according to the third Stribeck curve is specifically as follows: Respectively fit the mixed lubrication part and the elastohydrodynamic lubrication part in the third Stribeck curve with linear functions to obtain the first linear curve y1 = k1x + b1 and the second linear curve y2 = k2x + b2; Substitute the load W into the first linear curve and the second linear curve respectively. At the same time, determine the comprehensive viscosity η of the water-lubricated bearing load-bearing area after injecting the second lubricating medium according to the supply quantity q. Substitute the viscosity η0 of pure water into the first linear curve, and substitute the comprehensive viscosity η of the water-lubricated bearing load-bearing area into the second linear curve to obtain Let y1 = y2 and solve for v x This is the critical speed.

4. A system for determining the critical speed of a water-lubricated bearing into which a second lubricating medium is injected, characterized in that, It includes: A pure water Stribeck curve measurement unit, a second lubricant medium Stribeck curve measurement unit, a Stribeck curve synthesis unit, and a critical speed determination unit; The pure water Stribeck curve measurement unit is used to use pure water as the lubricant for the water-lubricated bearing and measure the first Stribeck curve of the current water-lubricated bearing body. The ordinate of the first Stribeck curve is the coefficient of friction cof, and the abscissa is the first bearing characteristic coefficient η0v / W, where η0 is the viscosity of pure water, v is the sliding speed, and W is the load; The second lubricant Stribeck curve measuring unit is used to measure the second Stribeck curve of the current water lubricated bearing body by using an oily second lubricant as the lubricant for the water lubricated bearing. The ordinate of the second Stribeck curve is the coefficient of friction cof, and the abscissa is the second bearing characteristic coefficient η Δ v / W, where η Δ is the viscosity of the second lubricant; The Stribeck curve synthesis unit is used to synthesize a third Stribeck curve by combining a first Stribeck curve and a second Stribeck curve, and the third Stribeck curve is defined as a function C = f(S), where C is the coefficient of friction cof and S is the third bearing characteristic coefficient ηv / W, where η is the comprehensive viscosity of the water-lubricated bearing load-carrying area after injecting the second lubricating medium, and there is the following relationship between η and the supply quantity q of the second lubricating medium: η = kq R , where k is a coefficient dependent on the water-lubricated bearing system and the viscosity of the second lubricating medium, and R is the supply quantity index coefficient; The critical speed determination unit is used to obtain the load W of the given water-lubricated bearing and the supply amount q of the second lubricant medium, and determine the rotational speed at which the coefficient of friction at the lubrication state point when the lubricant is pure water is equal to the coefficient of friction at the lubrication state point after injecting the second lubricant medium with a supply amount of q according to the third Stribeck curve, and determine this rotational speed as the critical speed.

5. A system for determining the critical speed of a water-lubricated bearing injecting a second lubricant medium, according to claim 4, wherein The method for the Stribeck curve synthesis unit to synthesize the third Stribeck curve is specifically as follows: Take the friction coefficient cof on the vertical axis in the first Stribeck curve and the second Stribeck curve as the vertical axis of the third Stribeck curve; Calculate the third bearing characteristic coefficient based on the viscosity, speed, and load corresponding to each measurement point in the first Stribeck curve and the second Stribeck curve, and finally take the calculated result as the horizontal axis of the third Stribeck curve to form the third Stribeck curve.

6. A system for determining the critical speed of a water-lubricated bearing into which a second lubricating medium is injected according to claim 5, characterized in that, The method for the critical speed determination unit to determine the speed at which the friction coefficients of the lubrication state point when the lubricant is pure water and the lubrication state point after injecting the second lubricant medium with a supply amount of q are equal according to the third Stribeck curve is specifically as follows: Respectively fit the mixed lubrication part and the elastohydrodynamic lubrication part in the third Stribeck curve with linear functions to obtain the first linear curve y1 = k1x + b1 and the second linear curve y2 = k2x + b2; Substitute the load W into the first linear curve and the second linear curve respectively. At the same time, determine the comprehensive viscosity η of the water-lubricated bearing load-bearing area after injecting the second lubricating medium according to the supply quantity q. Substitute the viscosity η0 of pure water into the first linear curve, and substitute the comprehensive viscosity η of the water-lubricated bearing load-bearing area into the second linear curve to obtain Let y1 = y2 and solve for v x This is the critical speed.

7. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that: When the processor executes the program, it implements the method for determining the critical speed of a water-lubricated bearing injected with a second lubricant medium as described in any one of claims 1 to 3.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by the processor, it implements the method for determining the critical speed of a water-lubricated bearing injected with a second lubricant medium as described in any one of claims 1 to 3.

9. A method for regulating the critical speed of a water-lubricated bearing injecting a second lubricating medium, characterized in that Including the following steps: Based on the method described in any one of claims 1-3, determine the relationship between the critical speed of the water-lubricated bearing, the load W, and the supply amount q of the second lubricant medium; According to the relationship between the critical speed of the water-lubricated bearing, the load W, and the supply amount q of the second lubricant medium, adjust the load W or the supply amount q of the second lubricant medium to control the critical speed of the water-lubricated bearing.

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