Life prediction method of crane transmission system based on fatigue load spectrum

Abstract

The present application provides a crane transmission system life prediction method based on fatigue load spectrum, which relates to the field of crane technology. The method comprises: obtaining the load spectrum of a part; obtaining the original S-N curve of the part; dividing the load in the load spectrum into low-amplitude load and high-amplitude load, and calibrating the optimal number of strengthening exercises for the low-amplitude load. Y Calculate the ratio of fatigue strength increase after low-load strengthening to obtain the strengthening ratio Z; form a new S-N curve for the part; apply low-amplitude load to the part until the optimal strengthening training number Y After that, a high load is applied and the high load damage is calculated using the new S-N curve. D 1 Apply all loads in the entire load spectrum and calculate the full spectrum damage using the new S-N curve D 2 ;according to D 1 and D 2 , calculate the total life of the parts. It comprehensively considers the strengthening effect of low-amplitude loads and the damage of high-amplitude loads, overcoming the defect of traditional fatigue cumulative damage model that ignores the strengthening effect of low-amplitude loads.

Description

Technical Field

[0001] The present invention relates to the technical field of lifting machinery, and in particular to a method for predicting the life of a crane transmission system based on fatigue load spectrum. Background Art

[0002] In terms of structural safety assessment, recent research on fatigue and life prediction for cranes, both domestically and internationally, has focused on several key areas. First, by analyzing crane accidents caused by fatigue using finite element analysis and fracture mechanics theory, recommendations for fatigue-resistant design have been proposed. Second, finite element analysis has been conducted on crane girders to detect crack size and predict fatigue life based on fatigue crack growth rate formulas. Recent literature on fatigue damage analysis and life prediction for cranes reveals that methods for crane fatigue and life prediction include fracture mechanics theory and the SN curve method:

[0003] Based on fracture mechanics theory, life predictions for fatigue-damaged cranes are performed using different crack growth rate models. Qu Xiaogang et al. developed a numerical simulation model for fatigue life prediction and used the fatigue stress-time history of critical fatigue points to estimate the remaining fatigue life of crane metal structures. Xu Gening et al. combined metal structure theory with the rainflow counting method to obtain a two-parameter, two-dimensional stress spectrum at critical points on the main beam within one year. They then applied the Paris formula to predict crack growth and thus determine the remaining fatigue life.

[0004] SN curve method: Finite element analysis of the crane structure is performed to identify locations prone to fatigue cracking. Based on the load conditions at these localized locations, fatigue life prediction software, such as the Fatigue module or FE-Safe in Ansys, is used. Based on the material's SN curve, a series of processing and transformations are performed to obtain the SN curve under actual operating conditions, thereby enabling fatigue life prediction and analysis. Liu Junqing et al. used Ansys to establish a tower boom weld node model and completed the conversion of mesh-insensitive structural stresses using the equivalent structural stress method. Combined with the fatigue design master SN curve, they analyzed the fatigue life of the tower boom weld node.

[0005] Using fracture mechanics theory to predict crane lifespans can improve accuracy and reliability, but this method is relatively complex, costly, and relies on precise material properties and load data. Therefore, practical applications require a balance between its advantages and limitations. Fatigue life prediction methods based on SN curves are readily applicable to practical projects due to their simplicity and ease of use. However, this method presupposes the availability of SN curves for the lifespan prediction target, derived from extensive fatigue testing. This is quite scarce in the crane industry. Currently, SN curves for crane structures are still unavailable. Instead, SN curves for Q235B and Q345B, commonly used metal materials for metal structures, can be interpolated for different structural stress concentration factors and different stress states. Furthermore, this method does not consider the effect of load sequence, yet historical loading conditions significantly influence the overall lifespan of fatigue cracks. Summary of the Invention

[0006] To address this issue, the present invention provides a crane transmission system life prediction method based on fatigue load spectra. This method aims to address the current lack of SN curves for crane structures, requiring interpolation based on SN curves for commonly used metal materials such as Q235B and Q345B for different structural stress concentration factors and stress states. Furthermore, this method fails to consider the effects of load sequence, a significant technical issue in predicting fatigue crack life, where historical load conditions significantly influence overall lifespan.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] The present invention provides a method for predicting the life of a crane transmission system based on a fatigue load spectrum, comprising the following steps:

[0009] Step S1, obtaining the load spectrum of the part;

[0010] Step S2, obtaining the original SN curve of the part;

[0011] Step S3: Divide the load in the load spectrum into low-amplitude load and high-amplitude load, and calibrate the optimal number of strengthening exercises for low-amplitude load Y ;

[0012] Step S4, calculating the ratio of the fatigue strength improvement of the part after low-load strengthening to obtain the strengthening ratio Z;

[0013] Step S5: forming a new SN curve of the part according to the strengthening ratio Z;

[0014] Step S6: Apply low-amplitude load to the parts until the optimal strengthening exercise times are achieved. Y Then, perform the following steps:

[0015] a) Apply high load and use the new SN curve to calculate the high load damage D 1 ;

[0016] b) Apply all loads of the entire load spectrum and use the new SN curve to calculate the full spectrum damage D 2 ;

[0017] Step S7: D 1 and D 2 , calculate the total life of the parts.

[0018] In some embodiments of the present invention, step S4 includes:

[0019] Defining the load spectrum includes S Level stress, 1 ~ j The level is high load, j +1 ~ s level is low amplitude load, 1< j < S ; After low amplitude load strengthening i The fatigue life at the stress level is N i , No. i The number of cycles of the amplitude of the level load is n i , 1< i < S ;

[0020] Apply low-amplitude loads to parts for optimal strengthening times Y , the number of spectrum cycle blocks corresponding to this enhancement effect is (1)

[0021] According to i Low-amplitude load at optimal strengthening exercise times Y The corresponding fatigue strength improvement ratio Z i , we can get the fatigue strength improvement ratio Z of the part at the optimal point, that is, (2).

[0022] In some embodiments of the present invention, in step S6, a low-amplitude load is applied to the part until the optimal strengthening exercise times are reached. Y Then, perform the following steps:

[0023] Imposition M 1 The block stress level is 1~ j Under the new SN curve, according to Miner's law, the damage amount under high load isD 1 for (3)

[0024] According to the load spectrum, the stress level is 1~ s The load is applied until the part breaks due to fatigue. The number of spectrum cycles is M 2 , full spectrum damage D 2 for (4)

[0025] Calculate high load damage according to the new SN curve D 1 and full spectrum damage D 2 The sum is 1, that is (5)

[0026] From this we get: , the total number of cyclic spectrum blocks in the experiment is: , total number of test cycles , substitute equations (1) to (5) to obtain the total number of test cycles N for (6)

[0027] Where: n 0 Optimal strengthening reps for low-amplitude loads Y , n i For the i Number of load cycles, N i After strengthening for low amplitude load i Fatigue life at the highest stress level.

[0028] In some embodiments of the present invention, the part includes a bearing; in step S2, an original SN curve of the bearing is obtained by a bearing life testing device; the bearing life testing device includes:

[0029] An outer ring fixing mechanism, used for fixing the outer ring of the bearing;

[0030] An inner ring fastening mechanism, used for fastening together with the inner ring of the bearing;

[0031] a driving mechanism for rotating the inner ring fastening mechanism and the inner ring of the bearing together;

[0032] The radial loading mechanism is used to apply a radial load to the inner ring of the bearing.

[0033] In some embodiments of the present invention, the outer ring fixing mechanism includes a fixing cylinder, a plurality of test tubes are distributed on the circumferential side wall of the fixing cylinder, a support block is provided on the inner wall of the test tube, and an end cover is detachably connected to the end of the test tube, and the support block and the end cover cooperate with each other to fix the outer ring of the bearing.

[0034] In some embodiments of the present invention, the inner ring fastening mechanism includes:

[0035] a bracket, disposed in the fixing cylinder;

[0036] A movable box is disposed in the fixed cylinder and is connected to the bracket in a transverse sliding manner;

[0037] A rotating column, rotatably connected to the movable box;

[0038] a support rod located in the test tube, the support rod being slidably connected to one end of the rotating column, a plurality of the support rods being distributed in a circular array and capable of being brought together or separated, and the support rods being capable of contacting the inner ring of the bearing;

[0039] a movable column, one end of which is disposed in the rotating column and is capable of sliding along the radial direction of the rotating column;

[0040] A connecting rod has one end hinged to the support rod and the other end hinged to the movable column.

[0041] In some embodiments of the present invention, the driving mechanism includes:

[0042] A driving spindle is movable transversely through a side wall of the movable box. The driving spindle has two limiting protrusions. A side wall of the movable box is located between the two limiting protrusions. The two limiting protrusions are in indirect contact with the side wall of the movable box through a pressure sensor.

[0043] A driving bevel gear is located in the movable box and is mounted on the driving spindle;

[0044] The driven bevel gear is located in the movable box and is installed on the rotating column. The driven bevel gear is meshed with the driving bevel gear.

[0045] In some embodiments of the present invention, the radial loading mechanism comprises:

[0046] a transmission box having an input end, a first output end, and a second output end;

[0047] a first loading rod, located outside the fixed cylinder, one end of which is rotatably connected to the driving spindle; one end of the driving spindle has a polygonal cross-section and is plugged into the first output end of the transmission box;

[0048] A cooling water jacket having a water inlet and a water outlet, the cooling water jacket covering the outside of the movable box;

[0049] a circulating water pump, a driving end of which is connected to the second output end of the transmission box;

[0050] The first radiating pipe, the water outlet of the cooling water jacket, the inlet of the circulating water pump, the outlet of the circulating water pump, the first radiating pipe, and the water inlet of the cooling water jacket can be connected in sequence;

[0051] a first loading plate, one side of which is planar and the other side of which is curved; the first loading plate is located in the first heat dissipation tube, the first loading plate is connected to one end of the first loading rod, and the first loading plate can move laterally in the first heat dissipation tube;

[0052] The reset member is used to reset the movable box after it moves horizontally.

[0053] In some embodiments of the present invention, the radial loading mechanism further comprises:

[0054] The second radiating pipe, the water outlet of the cooling water jacket, the inlet of the circulating water pump, the outlet of the circulating water pump, the second radiating pipe, and the water inlet of the cooling water jacket can be connected in sequence;

[0055] a second loading rod, located outside the fixed cylinder, one end of the second loading rod being rotatably connected to the driving spindle;

[0056] a second loading plate having a flat surface on one side and an arc-shaped surface on the other side; the second loading plate is located within the second heat dissipation tube and is connected to one end of the second loading rod; the second loading plate is capable of moving laterally within the second heat dissipation tube, and the second loading plate and the first loading plate move in opposite directions;

[0057] The switching valve has a first interface, a second interface and a third interface, the first interface is connected to the outlet of the circulating water pump, the second interface is connected to the first radiating pipe, and the third interface is connected to the second radiating pipe.

[0058] In some embodiments of the present invention, a movable valve plate is movably provided in the switching valve, and the movable valve plate divides the internal space of the switching valve into a first guide chamber and a second guide chamber; when the movable valve plate moves upward, the outlet of the circulating water pump, the first guide chamber, and the first heat dissipation pipe can be connected in sequence; when the movable valve plate moves downward, the outlet of the circulating water pump, the second guide chamber, and the second heat dissipation pipe can be connected in sequence;

[0059] The radial loading mechanism further comprises:

[0060] a sliding sleeve, slidably connected to the second output end of the transmission box;

[0061] a first connecting rod, one end of which is connected to a counterweight ball and the other end of which is rotatably connected to the second output end of the transmission box;

[0062] a second connecting rod, one end of which is rotatably connected to the sliding sleeve and the other end of which is rotatably connected to the middle portion of the first connecting rod;

[0063] a first rotating shaft rotatably connected to a side wall of the switching valve;

[0064] a first rotating disk, located in the switching valve and mounted on the first rotating shaft;

[0065] a third connecting rod, one end of which is rotatably connected to the movable valve plate and the other end of which is rotatably connected to the eccentric portion of the first rotating disk;

[0066] When the sliding sleeve moves downward, the movable valve plate does not move; each time the sliding sleeve moves upward to the maximum displacement, the movable valve plate can complete one upward or downward movement.

[0067] The embodiments of the present invention have at least the following advantages or beneficial effects:

[0068] It comprehensively considers the strengthening effect of low-amplitude loads and the damage of high loads, overcomes the defect of traditional fatigue cumulative damage model that ignores the strengthening effect of low-amplitude loads, and provides a theoretical basis for quickly and reliably evaluating the fatigue life of parts under spectrum loads.

[0069] Other features and advantages of the present invention will be set forth in the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0071] Figure 1 The figure is a flow chart of the crane transmission system life prediction method based on fatigue load spectrum;

[0072] Figure 2 Schematic diagram of the original SN curve and the new SN curve of the part;

[0073] Figure 3 This is a structural diagram of the bearing life test equipment;

[0074] Figure 4 for Figure 3 A partial enlarged view of position A in the middle;

[0075] Figure 5 for Figure 3 A partial enlarged view of position B in the middle;

[0076] Figure 6 This is a schematic diagram showing that the direction in which the first one-way bearing allows the first rotating shaft to rotate is opposite to the direction in which the second one-way bearing allows the second rotating shaft to rotate. The arrows in the figure are used to indicate the direction of rotation.

[0077] icon:

[0078] 11-fixed cylinder, 12-test tube, 13-support block, 14-end cover,

[0079] 21- bracket, 22- movable box, 23- rotating column, 24- support rod, 25- movable column, 26- connecting rod,

[0080] 31-driving spindle, 32-driving bevel gear, 33-driven bevel gear,

[0081] 41-transmission box, 411-input end, 412-first output end, 413-second output end, 42-first loading rod, 421-connecting sleeve, 431-water inlet, 432-water outlet, 44-circulating water pump, 45-first heat dissipation pipe, 46-first loading plate, 47-reset member,

[0082] 48 - second heat dissipation pipe, 49 - second loading rod, 51 - second loading plate, 52 - switching valve, 521 - first interface, 522 - second interface, 523 - third interface, 524 - movable valve plate,

[0083] 53-sliding sleeve, 54-first connecting rod, 55-second connecting rod, 56-first rotating shaft, 57-first rotating disk, 58-third connecting rod, 59-counterweight ball,

[0084] 61 - second rotating shaft, 62 - second rotating disk, 63 - fourth connecting rod, 64 - fifth connecting rod, 65 - first one-way bearing, 66 - second one-way bearing. DETAILED DESCRIPTION

[0085] In the following, only certain exemplary embodiments are briefly described. As those skilled in the art would realize, the described embodiments may be modified in various different ways without departing from the spirit or scope of the embodiments of the present invention.

[0086] In the description of the embodiments of the present invention, it should be understood that the terms "lateral", "upper", "lower", "left", "right", "top", "inner", "outer", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present invention.

[0087] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0088] In the embodiments of the present invention, unless otherwise expressly specified or limited, the terms "installed," "connected," "connected," "fixed," etc. should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; they may refer to direct connection or indirect connection through an intermediate medium; they may refer to internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of the present invention based on specific circumstances.

[0089] The embodiments of the present invention are described in detail below.

[0090] Example 1

[0091] See also Figure 1~Figure 2 This embodiment provides a method for predicting the life of a crane transmission system based on a fatigue load spectrum. The crane transmission system includes parts such as bearings.

[0092] The above method comprises the following steps:

[0093] Step S1, obtaining the load spectrum of the part;

[0094] Step S2, obtaining the original SN curve (also called lgS - lgN curve) of the part;

[0095] Step S3: Divide the load in the load spectrum into low-amplitude load and high-amplitude load, and calibrate the optimal number of strengthening exercises for low-amplitude load Y ;

[0096] Step S4, calculating the ratio of the fatigue strength improvement of the part after low-load strengthening to obtain the strengthening ratio Z;

[0097] Step S5: forming a new SN curve of the part according to the strengthening ratio Z;

[0098] Step S6: Apply low-amplitude load to the parts until the optimal strengthening exercise times are achieved. Y After (damage is 0), perform the following steps:

[0099] a) Apply high load and use the new SN curve to calculate the high load damage D 1 ;

[0100] b) Apply all loads of the entire load spectrum and use the new SN curve to calculate the full spectrum damage D 2 ;

[0101] Step S7: D 1 and D 2 , calculate the total life of the parts.

[0102] The original SN curve can be obtained through experiments or simulations; the optimal number of strengthening exercises Y It can be calibrated through experiments; the acquisition of the load spectrum includes: obtaining the original strain data of the part, using the rain flow counting method to generate the load amplitude-mean matrix, and thus constructing the load spectrum.

[0103] Step S4 includes:

[0104] Defining the load spectrum includes S Level stress, 1 ~ j The level is high load, j +1 ~ s level is low amplitude load, 1< j < S ; After low amplitude load strengthening i The fatigue life at the stress level is N i , No. i The amplitude cycle number (number of load cycles) of the level load is n i , 1< i < S ;

[0105] Apply low-amplitude loads to parts for optimal strengthening times Y , the number of spectrum cycle blocks corresponding to this enhancement effect is (1)

[0106] According to i Low-amplitude load at optimal strengthening exercise times Y The corresponding fatigue strength improvement ratio Z i (Z i It can be calibrated by test) to obtain the fatigue strength improvement ratio Z of the part at the optimal point, that is, (2)

[0107] In step S6, a low amplitude load is applied to the part until the optimal strengthening exercise times are reached. Y Then, perform the following steps:

[0108] Imposition M 1 The block stress level is 1~ j Under the new SN curve, according to Miner's law, the damage amount under high load is D 1 (i.e., the cumulative damage of a high load with a cyclic stress level of 1 to j) is (3)

[0109] According to the load spectrum, the stress level is 1~ s The load is applied until the part breaks due to fatigue. The number of spectrum cycles is M 2 , full spectrum damage D 2 (Cumulative damage in one cycle test) is (4)

[0110] Apply low-amplitude loads to parts for optimal strengthening times Y After that, the strength of the part increases and a new SN curve is generated. When using Miner theory to calculate the damage amount, it is only necessary to calculate the high load damage amount according to the new SN curve. D 1 and full spectrum damage D 2 The sum is 1, that is (5)

[0111] From this we get: , the total number of cyclic spectrum blocks in the experiment is: , total number of test cycles , substitute equations (1) to (5) to obtain the total number of test cycles N for (6)

[0112] Where: n 0 This is the optimal number of strengthening exercises with low loads Y .

[0113] Step S5 includes:

[0114] Low-amplitude load refers to the load whose corresponding stress amplitude is lower than the fatigue limit of the material. Based on the low-load strengthening characteristics of the material, the low-amplitude load below the fatigue limit is divided into loads with strengthening effect and loads without strengthening effect. According to the strength of the material, the stress with strengthening effect is about within the range.

[0115] Assuming that the optimal strengthening exercise times are achieved at each level of low-amplitude load Y Previously, the improvement ratio of the fatigue strength of parts was linearly cumulative, that is, the maximum strengthening ratio corresponded to the optimal strengthening times, and the sum of the ratios of the fatigue strength improvement of each level of low-amplitude load was Z Expressed as (7)

[0116] Where: n i For the i The number of times the load acts, Y is the corresponding optimal number of strengthening exercises, Z i For the i Low-amplitude load at optimal strengthening exercise times Y The corresponding fatigue strength improvement ratio ( Z i can be calibrated through testing).

[0117] In order to reduce the complexity of calculating the new SN curve, within the linear range, there is or (8)

[0118] like Figure 2 As shown, the part is subjected to a low amplitude load for an appropriate number of times (optimal strengthening exercise number Y ) after exercise, the strength of the structure is improved (from S1 to S0), and the original SN curve keeps its slope unchanged and moves upward as a whole, forming a new SN curve.

[0119] The above method comprehensively considers the strengthening effect of low-amplitude loads and the damage of high loads, overcoming the defect of traditional fatigue cumulative damage model that ignores the strengthening effect of low-amplitude loads, and provides a theoretical basis for quickly and reliably evaluating the fatigue life of parts under spectrum loads.

[0120] Example 2

[0121] See also Figures 1 to 6 This embodiment provides a bearing life test device, which is used to obtain the original SN curve of the bearing part through experiments in step S2. The bearing life test device includes an outer ring fixing mechanism, an inner ring fastening mechanism, a driving mechanism and a radial loading mechanism.

[0122] The outer ring fixing mechanism is used to fix the outer ring of the bearing; the inner ring fastening mechanism is used to fasten it together with the inner ring of the bearing; the driving mechanism is used to make the inner ring fastening mechanism and the inner ring of the bearing rotate together; the radial loading mechanism is used to apply a load to the inner ring of the bearing along the radial direction of the bearing.

[0123] The outer ring fixing mechanism includes a fixing cylinder 11, and multiple test tubes 12 are distributed on the circumferential side wall of the fixing cylinder 11. Support blocks 13 are provided on the inner walls of the test tubes 12. The ends of the test tubes 12 are detachably connected to end covers 14. The support blocks 13 and the end covers 14 cooperate with each other to fix the outer ring of the bearing.

[0124] Place the bearing into the test tube 12, with the support block 13 in contact with one end of the bearing outer ring. After installing the end cover 14, the bearing can be fixed by squeezing.

[0125] The inner ring fastening mechanism includes a bracket 21 , a movable box 22 , a rotating column 23 and a support rod 24 .

[0126] The bracket 21 is disposed in the fixing tube 11 .

[0127] The movable box 22 is disposed in the fixed cylinder 11 and is connected to the bracket 21 in a transverse sliding manner.

[0128] The rotating column 23 is rotatably connected to the movable box 22 .

[0129] The support rod 24 is located in the test tube 12 and is slidably connected to one end of the rotating column 23. The support rods 24 are distributed in a circular array and can be gathered or separated from each other. The support rods 24 can contact the inner ring of the bearing.

[0130] After the bearing is placed in the test tube 12 and the end cover 14 is installed, the plurality of struts 24 are separated and spread out, and the struts 24 are in contact with the inner ring of the bearing to fasten the struts 24 and the inner ring of the bearing together.

[0131] The driving mechanism includes a driving spindle 31 , a driving bevel gear 32 and a driven bevel gear 33 .

[0132] The driving spindle 31 moves laterally through a side wall of the movable box 22. The driving spindle 31 has two limiting protrusions. A side wall of the movable box 22 is located between the two limiting protrusions. The two limiting protrusions are in indirect contact with the side wall of the movable box 22 through a pressure sensor.

[0133] The driving bevel gear 32 is located in the movable box 22 and is mounted on the driving main shaft 31 .

[0134] The driven bevel gear 33 is located in the movable box 22 and is mounted on the rotating column 23 . The driven bevel gear 33 is meshed with the driving bevel gear 32 .

[0135] When the main shaft 31 is driven to rotate, the rotating column 23 is driven to rotate, and the rotating column 23 then drives the support rod 24 and the inner ring of the bearing to rotate.

[0136] The radial loading mechanism includes a transmission box 41 and a first loading rod 42 .

[0137] The transmission box 41 has an input end 411 , a first output end 412 , and a second output end 413 .

[0138] The first loading rod 42 is located outside the fixed cylinder 11 , and one end of the first loading rod 42 is rotatably connected to the driving spindle 31 through a connecting sleeve 421 ; one end of the driving spindle 31 has a polygonal cross-section and is plugged into the first output end 412 of the transmission box 41 .

[0139] The input end 411 of the transmission box 41 can be connected to a motor (not shown). The first output end 412 of the transmission box 41 can drive the drive spindle 31 to rotate. At the same time, by applying a lateral force to the first loading rod 42, a radial load can be applied to the bearing inner ring through the transmission of the drive spindle 31, the rotating column 23, and the support rod 24. By adjusting the lateral force applied to the first loading rod 42, the radial load applied to the bearing inner ring can be adjusted.

[0140] As can be seen from the foregoing, this embodiment can simultaneously test multiple bearings and apply an adjustable radial load to the bearing inner rings. By installing corresponding strain sensors at appropriate locations on the bearings, strain data can be collected from the bearings under the corresponding radial loads, facilitating the acquisition of the bearing's original SN curve. Furthermore, by installing end caps 14 on each test tube 12, the interior spaces of the test tubes 12 and the fixed cylinder 11 are sealed and isolated from the external environment. By connecting external equipment, the temperature, humidity, and other conditions within the test tubes 12 and fixed cylinder 11 can be adjusted to simulate the actual operating environment of the bearings.

[0141] Example 3

[0142] This embodiment is an improvement on the basis of embodiment 2.

[0143] See also Figures 1 to 6 The inner ring fastening mechanism also includes a movable column 25 and a connecting rod 26.

[0144] One end of the movable post 25 is disposed in the rotating post 23 and is capable of sliding along the radial direction of the rotating post 23 .

[0145] One end of the connecting rod 26 is hinged to the support rod 24 , and the other end is hinged to the movable column 25 .

[0146] During the rotation of the drive spindle 31, rotating column 23, and struts 24, as the speed of the drive spindle 31 increases, the rotation speed of the rotating column 23 also increases. Under the action of centrifugal force, the movable column 25 extends outward from the rotating column 23, driving the struts 24 away from each other, so that the side walls of the struts 24 contact the inner side of the inner ring of the bearing, thereby conveniently connecting the struts 24 to the inner ring of the bearing. In addition, as the speed of the drive spindle 31 and rotating column 23 increases, the contact between the struts 24 and the inner ring of the bearing becomes tighter, thus preventing slippage between the struts 24 and the inner ring of the bearing.

[0147] The radial loading mechanism further includes a cooling water jacket, a circulating water pump 44 , a first heat dissipation pipe 45 , a first loading plate 46 and a reset member 47 .

[0148] The cooling water jacket has a water inlet 431 and a water outlet 432 , and is wrapped around the outside of the movable box 22 .

[0149] A driving end of the circulating water pump 44 is connected to the second output end 413 of the transmission box 41 .

[0150] The outer wall of the first heat dissipation pipe 45 has heat dissipation fins to enhance the heat dissipation effect. The water outlet 432 of the cooling water jacket, the inlet of the circulating water pump 44, the outlet of the circulating water pump 44, the first heat dissipation pipe 45, and the water inlet 431 of the cooling water jacket can be connected in sequence.

[0151] One side of the first loading plate 46 is flat and the other side is curved; the first loading plate 46 is located in the first heat dissipation tube 45, and the first loading plate 46 is connected to one end of the first loading rod 42, and the first loading plate 46 can move laterally in the first heat dissipation tube 45.

[0152] One end of the reset member 47 is connected to the inner wall of the fixed cylinder 11, and the other end is connected to the outer wall of the movable box 22. The reset member 47 is used to reset the movable box 22 after it moves horizontally. The reset member 47 is, for example, a spring.

[0153] See also Figure 3The cooling water jacket, circulating water pump 44, and first heat dissipation pipe 45 cool the transmission components within the movable housing 22, ensuring their stability and preventing high temperatures from affecting their lifespan. The curved side of the first loading plate 46 experiences a higher flow rate than the flat side. The higher flow rate creates lower pressure, enabling the first loading plate 46 to drive the first loading rod 42 and the drive spindle 31 rightward (actually, there is a tendency to move rightward). The drive spindle 31, in turn, drives the movable housing 22 rightward (actually, there is a tendency to move rightward) via the stopper protrusion. The movable housing 22, in turn, drives the rotating column 23 and strut 24, thereby applying a rightward radial load to the bearing inner ring. The faster the flow rate within the first heat dissipation pipe 45, the greater the radial load applied to the bearing inner ring via the first loading plate 46.

[0154] Example 4

[0155] This embodiment is improved on the basis of embodiment 3.

[0156] See also Figures 1 to 6 The radial loading mechanism further includes a second heat dissipation tube 48 , a second loading rod 49 , a second loading plate 51 and a switching valve 52 .

[0157] The outer wall of the second heat dissipation pipe 48 has heat dissipation fins to enhance the heat dissipation effect. The water outlet 432 of the cooling water jacket, the inlet of the circulating water pump 44, the outlet of the circulating water pump 44, the second heat dissipation pipe 48, and the water inlet 431 of the cooling water jacket can be connected in sequence.

[0158] The second loading rod 49 is located outside the fixed cylinder 11 , and one end of the second loading rod 49 is rotatably connected to the driving main shaft 31 through a connecting sleeve 421 .

[0159] One side of the second loading plate 51 is flat and the other side is curved; the second loading plate 51 is located in the second heat dissipation tube 48, and the second loading plate 51 is connected to one end of the second loading rod 49. The second loading plate 51 can move laterally in the second heat dissipation tube 48, and the movement directions of the second loading plate 51 and the first loading plate 46 are opposite.

[0160] The switching valve 52 has a first interface 521, a second interface 522 and a third interface 523. The first interface 521 is connected to the outlet of the circulating water pump 44, the second interface 522 is connected to the first heat dissipation pipe 45, and the third interface 523 is connected to the second heat dissipation pipe 48; the switching valve 52 is used to allow the water in the cooling water jacket to flow through the first heat dissipation pipe 45 or the second heat dissipation pipe 48.

[0161] The principle of the second loading plate 51 driving the driving spindle 31 is the same as the principle of the first loading plate 46 driving the driving spindle 31. The flow path of the water in the cooling water jacket is changed by switching valve 52; see Figure 3When water flows through the first heat dissipation tube 45, the first loading plate 46 drives the driving spindle 31 to move right. When water flows through the second heat dissipation tube 48, the second loading plate 51 drives the driving spindle 31 to move left, thereby changing the direction of the radial load applied to the inner ring of the bearing.

[0162] See also Figure 3 and Figure 5 A movable valve plate 524 is movably provided in the switching valve 52. The movable valve plate 524 divides the internal space of the switching valve 52 into a first guide chamber and a second guide chamber. After the movable valve plate 524 moves upward, the outlet of the circulating water pump 44, the first guide chamber, and the first heat dissipation pipe 45 can be connected in sequence; after the movable valve plate 524 moves downward, the outlet of the circulating water pump 44, the second guide chamber, and the second heat dissipation pipe 48 can be connected in sequence.

[0163] Example 5

[0164] This embodiment is improved on the basis of embodiment 4.

[0165] See also Figures 1 to 6 The radial loading mechanism further includes a sliding sleeve 53 , a first connecting rod 54 , a second connecting rod 55 , a first rotating shaft 56 , a first rotating disk 57 and a third connecting rod 58 .

[0166] The sliding sleeve 53 is slidably connected to the second output end 413 of the transmission box 41 .

[0167] One end of the first connecting rod 54 is connected to the counterweight ball 59 , and the other end is rotatably connected to the second output end 413 of the transmission box 41 .

[0168] One end of the second connecting rod 55 is rotatably connected to the sliding sleeve 53 , and the other end is rotatably connected to the middle portion of the first connecting rod 54 .

[0169] The first rotating shaft 56 is rotatably connected to a side wall of the switching valve 52 .

[0170] The first rotary disk 57 is located in the switching valve 52 and is mounted on the first rotary shaft 56 .

[0171] One end of the third connecting rod 58 is rotatably connected to the movable valve plate 524 , and the other end is rotatably connected to the eccentric portion of the first rotary disk 57 .

[0172] When the sliding sleeve 53 moves downward, the movable valve plate 524 does not move; each time the sliding sleeve 53 moves upward to the maximum displacement, the movable valve plate 524 can complete one upward or downward movement to switch the waterway.

[0173] When the drive main shaft 31 and the driving end of the circulating water pump 44 are driven to rotate by the same motor, the greater the output power of the motor, the faster the speed of the driving end of the circulating water pump 44. Under the action of centrifugal force, the counterweight ball 59 will gradually lift upward, thereby driving the sliding sleeve 53 to move upward through the first connecting rod 54 and the second connecting rod 55. The sliding sleeve 53 drives the first rotating shaft 56 and the first rotating disk 57 to rotate a certain angle, so that the movable valve plate 524 moves upward to above the first interface 521, thereby connecting the outlet of the circulating water pump 44, the second guide chamber, and the second heat dissipation pipe 48 in sequence. When the motor is turned off, the sleeve 53 moves downward and resets while the movable valve plate 524 remains in its current position. When the direction of the radial load applied to the inner ring of the bearing needs to be changed, the motor is restarted and the output power of the motor is gradually increased. The sleeve 53 moves upward again, and the first rotating shaft 56 and the first rotating disk 57 are driven by the sleeve 53 to rotate a certain angle, so that the movable valve plate 524 moves downward to the bottom of the first interface 521, and the outlet of the circulating water pump 44, the first guide cavity, and the first heat dissipation pipe 45 are connected in sequence, thereby switching the water path and changing the direction of the radial load applied to the inner ring of the bearing.

[0174] Furthermore, the radial loading mechanism further includes a second rotating shaft 61 , a second rotating disk 62 , a fourth connecting rod 63 and a fifth connecting rod 64 .

[0175] The first rotating shaft 56 is connected to the side wall of the switching valve 52 via a first one-way bearing 65 , and the second rotating shaft 61 is connected to the first rotating shaft 56 via a second one-way bearing 66 .

[0176] The second rotating disk 62 is mounted on the second rotating shaft 61 .

[0177] One end of the fourth connecting rod 63 is connected to the sliding sleeve 53 .

[0178] One end of the fifth connecting rod 64 is rotatably connected to the fourth connecting rod 63 , and the other end is rotatably connected to the eccentric portion of the second rotating disk 62 .

[0179] The direction in which the first one-way bearing 65 allows the first rotating shaft 56 to rotate is opposite to the direction in which the second one-way bearing 66 allows the second rotating shaft 61 to rotate. When the sleeve 53 moves upward, the second rotating disk 62 rotates via the fifth connecting rod 64 and the fourth connecting rod 63. The second rotating disk 62 drives the second rotating shaft 61 to rotate. The second rotating shaft 61 drives the first rotating shaft 56 to rotate via the second one-way bearing 66. The first rotating shaft 56 drives the movable valve plate 524 upward to the top of the first interface 521 via the third connecting rod 58 to connect the outlet of the circulating water pump 44, the second guide cavity, and the second heat dissipation pipe 48 in sequence. When the motor is turned off, the sleeve 53 gradually moves downward under the action of gravity of the counterweight ball 59 and other components. During this process, the second rotating shaft 61 rotates while the first rotating shaft 56 does not rotate, and the second rotating disk 62 also does not rotate, and the movable valve plate 524 remains in its current position. When it is necessary to change the direction of the radial load on the inner ring of the bearing, restart the motor and gradually increase the output power of the motor to move the sleeve 53 up again. The sleeve 53 can drive the movable valve plate 524 to move down to the bottom of the first interface 521 through the transmission of the fourth connecting rod 63, the fifth connecting rod 64, the second turntable 62, the second rotating shaft 61, the first rotating shaft 56, etc., so as to connect the outlet of the circulating water pump 44, the first guide cavity, and the first heat dissipation pipe 45 in sequence, thereby switching the water path and changing the direction of the radial load applied to the inner ring of the bearing.

[0180] Finally, it should be noted that the above are merely preferred embodiments of the present application and are not intended to limit the present application. Persons skilled in the art will readily appreciate that the present application is susceptible to various modifications and variations. The embodiments and features of the embodiments may be combined arbitrarily without conflict. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A bearing life testing device comprising: An outer ring fixing mechanism, used for fixing the outer ring of the bearing; An inner ring fastening mechanism, used for fastening together with the inner ring of the bearing; a driving mechanism for rotating the inner ring fastening mechanism and the inner ring of the bearing together; a radial loading mechanism for applying a radial load to the inner ring of the bearing; The outer ring fixing mechanism includes a fixing cylinder, a plurality of test tubes are distributed on the circumferential side wall of the fixing cylinder, support blocks are provided on the inner walls of the test tubes, and end caps are detachably connected to the ends of the test tubes. The support blocks and the end caps cooperate with each other to fix the outer ring of the bearing; The inner ring fastening mechanism comprises: a bracket, disposed in the fixing cylinder; A movable box is disposed in the fixed cylinder and is connected to the bracket in a transverse sliding manner; A rotating column, rotatably connected to the movable box; a support rod located in the test tube, the support rod being slidably connected to one end of the rotating column, a plurality of the support rods being distributed in a circular array and capable of being brought together or separated, and the support rods being capable of contacting the inner ring of the bearing; a movable column, one end of which is disposed in the rotating column and is capable of sliding along the radial direction of the rotating column; A connecting rod, one end of which is hinged to the support rod and the other end of which is hinged to the movable column; The driving mechanism comprises: A driving spindle is movable transversely through a side wall of the movable box. The driving spindle has two limiting protrusions. A side wall of the movable box is located between the two limiting protrusions. The two limiting protrusions are in indirect contact with the side wall of the movable box through a pressure sensor. A driving bevel gear is located in the movable box and is mounted on the driving spindle; A driven bevel gear is located in the movable box and mounted on the rotating column, the driven bevel gear being meshed with the driving bevel gear; The radial loading mechanism comprises: a transmission box having an input end, a first output end, and a second output end; a first loading rod, located outside the fixed cylinder, one end of which is rotatably connected to the driving spindle; one end of the driving spindle has a polygonal cross-section and is plugged into the first output end of the transmission box; A cooling water jacket having a water inlet and a water outlet, the cooling water jacket covering the outside of the movable box; a circulating water pump, a driving end of which is connected to the second output end of the transmission box; The first radiating pipe, the water outlet of the cooling water jacket, the inlet of the circulating water pump, the outlet of the circulating water pump, the first radiating pipe, and the water inlet of the cooling water jacket can be connected in sequence; a first loading plate, one side of which is planar and the other side of which is curved; the first loading plate is located in the first heat dissipation tube, the first loading plate is connected to one end of the first loading rod, and the first loading plate can move laterally in the first heat dissipation tube; The reset member is used to reset the movable box after it moves horizontally.

2. The bearing life testing device according to claim 1, characterized in that: The radial loading mechanism further comprises: The second radiating pipe, the water outlet of the cooling water jacket, the inlet of the circulating water pump, the outlet of the circulating water pump, the second radiating pipe, and the water inlet of the cooling water jacket can be connected in sequence; a second loading rod, located outside the fixed cylinder, one end of the second loading rod being rotatably connected to the driving spindle; a second loading plate having a flat surface on one side and an arc-shaped surface on the other side; the second loading plate is located within the second heat dissipation tube and is connected to one end of the second loading rod; the second loading plate is capable of moving laterally within the second heat dissipation tube, and the second loading plate and the first loading plate move in opposite directions; The switching valve has a first interface, a second interface and a third interface, the first interface is connected to the outlet of the circulating water pump, the second interface is connected to the first radiating pipe, and the third interface is connected to the second radiating pipe.

3. The bearing life testing device according to claim 2, characterized in that: A movable valve plate is movably provided in the switching valve, and the movable valve plate divides the internal space of the switching valve into a first guide chamber and a second guide chamber. When the movable valve plate moves upward, the outlet of the circulating water pump, the first guide chamber, and the first heat dissipation pipe can be connected in sequence. When the movable valve plate moves downward, the outlet of the circulating water pump, the second guide chamber, and the second heat dissipation pipe can be connected in sequence. The radial loading mechanism further comprises: a sliding sleeve, slidably connected to the second output end of the transmission box; a first connecting rod, one end of which is connected to a counterweight ball and the other end of which is rotatably connected to the second output end of the transmission box; a second connecting rod, one end of which is rotatably connected to the sliding sleeve and the other end of which is rotatably connected to the middle portion of the first connecting rod; a first rotating shaft rotatably connected to a side wall of the switching valve; a first rotating disk, located in the switching valve and mounted on the first rotating shaft; a third connecting rod, one end of which is rotatably connected to the movable valve plate and the other end of which is rotatably connected to the eccentric portion of the first rotating disk; When the sliding sleeve moves downward, the movable valve plate does not move; each time the sliding sleeve moves upward to the maximum displacement, the movable valve plate can complete one upward or downward movement.

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