Rigidity matching method and structure of frequency-variable rigidity rotating arm node

Abstract

The invention discloses a rigidity matching method for a frequency-variable rigidity rotating arm node, which comprises the step of obtaining different longitudinal, vertical and transverse rigidities and a lower longitudinal-transverse rigidity ratio by adding different structures twice in the longitudinal direction and the vertical direction of a liquid rubber composite node mandrel, and relates to the technical field of locomotive part manufacturing. According to the rigidity matching method and structure of the frequency-variable rigidity rotating arm joint, different main body structures are formed in a secondary material adding mode, the longitudinal rigidity, the transverse rigidity and the vertical rigidity are rapidly adjusted, the project research and development cost is saved, and the product development period is shortened.

Description

Technical Field

[0001] The invention relates to the technical field of locomotive component manufacturing, in particular to a stiffness matching method and structure of a frequency-variable stiffness swing arm node. Background Art

[0002] China Standard EMU: referred to as BEM, refers to the EMU in which the Chinese standard system is dominant (among the 254 important standards, various Chinese standards account for 84%). Its functional standards and supporting track construction standards are higher than European and Japanese standards, and it has distinct and comprehensive Chinese characteristics. This also means that in the face of a diversified CRH environment (including four imported types and China's independently designed CRH6), China's EMUs are subject to standardized (unified) design for interconnection. This newly developed new type of EMU has added a large number of features such as compatibility and no derailment, thus forming a distinct and comprehensive Chinese feature, and is named the EMU Chinese Standard (Huabiao), representing the advanced standard system of the world's EMU technology. According to a method for preventing axle box bearing wear by changing the positioning method of a swing arm axle box disclosed in a Chinese patent document with announcement number CN106627640B, a method for preventing axle box bearing wear by adjusting the inclined surface structure of the rubber layer of the swing arm node is used. A two-section tapered inner hole swing arm node combination structure is adopted, and the rubber layers of the two swing arm nodes are arranged obliquely relative to each other. The characteristic is that the matching of the radial stiffness and the axial stiffness of the swing arm node is adjusted by changing the angle of the inclined surface of the rubber layer of the swing arm node, so that the longitudinal stiffness and deflection stiffness of the swing arm node are reduced, and at the same time, by increasing the axial stiffness, the torsional stiffness is avoided from decreasing, thereby effectively reducing the wear of the axle bearing.

[0003] Based on the search of the above patents and combined with the equipment in the prior art, it is found that the above equipment adopts different structural designs of the rubber body in the main structure design to achieve different stiffness adjustments. This method requires the design of different vulcanization molding molds and the processing of different metal parts, which is costly and has a long cycle. Summary of the invention

[0004] The object of the present invention is to provide a stiffness matching method structure of a frequency-variable stiffness swing arm node to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for matching the stiffness of a frequency-variable stiffness swing arm node, comprising adding different structures in the longitudinal and vertical directions of the core shaft of the liquid rubber composite node to obtain different longitudinal, vertical, and transverse stiffnesses and a lower longitudinal and transverse stiffness ratio; comprising the following steps: S1: Establishing the mechanical model: Based on the actual geometric shape, material properties and connection form of the swing arm node, the accurate mechanical model is established by applying the knowledge of theoretical mechanics, material mechanics and structural dynamics; S2: Modal analysis: Perform modal analysis on the established model to determine its natural frequency and vibration mode. By solving the eigenvalue problem, the natural frequencies of different orders and the corresponding vibration modes are obtained; S3: Determine stiffness matching: Based on the analysis in S1 and S2 and the desired frequency-dependent stiffness target, formulate a stiffness matching strategy and then add the physical structure; S4: Structural addition: Use a standard mandrel sample, and then use secondary addition around the mandrel to obtain different mandrel shape structures. The mandrel shape structure can be achieved by adjusting the height, width and angle of the secondary addition structure in the longitudinal and vertical directions; S5: Experimental verification: The steps of experimental verification include: S5.1: Experimental sample preparation; S5.2: Set up experimental equipment; S5.3: Static characteristics test; S5.4: Data analysis; S5.5: Reliability and repeatability verification.

[0006] As a further solution of the present invention: the stiffness matching strategy in S3 adopts variable stiffness elements, and parameter adjustment rules of these variable stiffness elements are set according to different frequency ranges.

[0007] As a further solution of the present invention: the secondary adding method in S4 includes injection molding, secondary vulcanization, welding, bonding, etc.

[0008] As a further scheme of the present invention: the secondary injection molding process places the raw materials into an injection molding mold, injects a plastic molding process, and uses injection molding to add polymer materials for a second time in the longitudinal and vertical directions of the standard core shaft to form different external structures, thereby achieving different longitudinal and lateral stiffness adjustments, secondary vulcanization: using a simple vulcanization mold in the longitudinal and lateral directions of the standard core shaft, vulcanize the rubber material onto the core shaft, and form internal structures of different shapes, thereby achieving different longitudinal and lateral stiffness adjustments; welding: using welding in the longitudinal and lateral directions of the standard core shaft, welding metal materials of the same material to the core shaft, which can quickly complete different structural adjustments and stiffness verifications; bonding: using glue bonding in the longitudinal and lateral directions of the standard core shaft, bonding components of different materials and shapes to the core shaft, forming different core shaft results, thereby achieving different longitudinal and lateral stiffness rapid adjustment.

[0009] As a further solution of the present invention: the secondary addition structure in S4 is specifically as follows: By adjusting the A dimension and ensuring that the lagging dimension C is a fixed value, usually 1~4mm, the hard stop function of different gaps H can be achieved in the longitudinal direction; The longitudinal stiffness of the product can be adjusted by the A dimension. When the A dimension increases, the longitudinal hard stop gap H decreases, and vice versa. The vertical stiffness can be adjusted by the B dimension. When the B dimension increases, the vertical stiffness also increases, and vice versa. The axial stiffness can be adjusted by adjusting the dimensions of E, F, and G. When dimension E increases and dimension F and angle G decrease, the lateral stiffness increases, and vice versa.

[0010] As a further solution of the present invention: the experimental steps of S5 are specifically as follows: according to the designed frequency-variable stiffness swing arm node structure, the physical sample of the swing arm node is accurately processed and manufactured to ensure that its dimensional accuracy, surface quality, etc. meet the design requirements, ensure that the installation position of these components is accurate, the connection is reliable, and its own performance is stable, and the conventional components in the swing arm node are strictly inspected for quality and dimensioned to avoid affecting the accuracy of the experimental results due to processing errors; Select a suitable vibration table or exciter to apply excitation forces of different frequencies. The frequency range should be able to cover the expected working frequency range of the swing arm node, and the excitation force can be precisely adjusted and controlled with sufficient accuracy and stability. Install the displacement sensor at the key position of the swing arm node to measure the displacement response of the swing arm under different frequency excitations. The measurement accuracy should be able to meet the experimental requirements to accurately capture small displacement changes and ensure the accuracy of force measurement. The error is controlled within a small range, such as the general accuracy can reach within 0.5% of the full scale. By slowly applying static force to the arm node, using force sensors and displacement sensors to measure the corresponding displacement under different static forces, the stiffness value of the arm node in static state is calculated, which is used as the basic data for subsequent dynamic experimental comparison and analysis; In order to ensure the reliability of the experimental results, after completing the above experiments, some experimental conditions can be changed or a newly manufactured swing arm node sample of the same specification can be replaced, and the above experimental process can be repeated to observe whether the obtained frequency-dependent stiffness curve and related experimental conclusions are consistent. If the results of multiple experiments have good repeatability and stability, then the effectiveness and reliability of the stiffness matching method and swing arm node design can be more powerfully demonstrated.

[0011] A stiffness matching structure of a frequency-variable stiffness swing arm node, comprising a symmetrically arranged left swing arm outer sleeve and a right swing arm outer sleeve and a symmetrically arranged left swing arm inner sleeve and a right swing arm inner sleeve, wherein the inner sleeves of the left swing arm inner sleeve and the right swing arm inner sleeve are provided with a core shaft, liquid rubber is provided between the core shaft and the inner walls of the left swing arm inner sleeve and the right swing arm inner sleeve, an inclined surface structure is provided on the outer surface of the core shaft and the inner sleeves of the left swing arm inner sleeve and the right swing arm inner sleeve, and the thickness of the liquid rubber on the left and right sides of the core shaft is less than the thickness of the liquid rubber on the upper and lower sides Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention provides a stiffness matching method, structure and method for a frequency-variable stiffness swing arm node, which adopts a secondary material addition method to form different main structures, and can quickly adjust the longitudinal, vertical and lateral stiffness of the liquid composite node over a large range, thereby obtaining ideal stiffness parameters.

[0012] 2. The present invention can reduce the difficulty of mandrel processing, reduce the high product cost, and shorten the mandrel processing cycle and product development cycle.

[0013] 3. The present invention can be widely applied to conventional rubber nodes of hollow-solid structures to achieve three-dimensional stiffness matching and obtain a lower longitudinal and transverse stiffness ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic cross-sectional view of the stiffness structure of the frequency-variable stiffness swing arm node in an embodiment of the present invention; Figure 2 Schematic diagram of the cross-sectional view of the stiffness structure of another viewing frequency variable stiffness swing arm node in an embodiment of the present invention; Figure 3 It is a cross-sectional schematic diagram in an embodiment of the present invention; Figure 4 Schematic diagram of the stiffness matching method in an embodiment of the present invention.

[0015] In the figure: 1. outer sleeve of left swivel arm; 2. outer sleeve of right swivel arm; 3. inner sleeve of left swivel arm; 4. inner sleeve of right swivel arm; 5. core shaft; 6. liquid rubber; 7. inclined surface structure. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present invention are clearly and completely described below in conjunction with the accompanying drawings.

[0017] Reference Figure 1-Figure 4 As shown, a stiffness matching method and structure of a frequency-variable stiffness swing arm node shown in the embodiment of the present invention is obtained by adding different structures in the longitudinal and vertical directions of the liquid rubber composite node core shaft for a second time, so as to obtain different longitudinal, vertical and lateral stiffness and a lower longitudinal and lateral stiffness ratio; wherein the swivel arm connection comprises a symmetrically arranged left swivel arm outer sleeve 1 and a right swivel arm outer sleeve 2 and a symmetrically arranged left swivel arm inner sleeve 3 and a right swivel arm inner sleeve 4, a core shaft 5 is sleeved inside the left swivel arm inner sleeve 3 and the right swivel arm inner sleeve 4, a liquid rubber 6 is arranged between the core shaft 5 and the inner walls of the left swivel arm inner sleeve 3 and the right swivel arm inner sleeve 4, an inclined surface structure 7 is arranged on the outer surface of the core shaft 5 and the inner sleeves of the left swivel arm 3 and the right swivel arm 4, and the thickness of the liquid rubber 6 on the left and right sides of the core shaft 4 is less than the thickness of the liquid rubber 6 on the upper and lower sides; The stiffness matching method includes the following steps: S1: Establishing a mechanical model: According to the actual geometric shape, material properties and connection form of the swing arm node, the knowledge of theoretical mechanics, material mechanics, structural dynamics and other knowledge is used to establish its accurate mechanical model; the lumped parameter model or finite element model is used for construction. Example: For a simpler swing arm node, the key parts are simplified to a combination of a spring-mass-damping system to simulate its dynamic behavior; for a complex structure, the finite element software is used to divide the mesh to accurately describe its mechanical characteristics; S2: Modal analysis: Perform modal analysis on the established model to determine its natural frequency and vibration mode. By solving the eigenvalue problem, the natural frequencies of different orders and the corresponding vibration modes are obtained; this step can help understand the natural vibration characteristics of the swing arm node itself without external complex excitation, and can pave the way for subsequent analysis of its response under external loads of different frequencies; if the vibration mode at certain key frequencies may have a significant impact on the overall structural stability or function, then it is necessary to focus on the adjustment of the stiffness near these frequencies; S3: Determine stiffness matching: Based on the analysis in S1 and S2 and the expected frequency-dependent stiffness target, formulate a stiffness matching strategy before adding the physical structure; the stiffness matching strategy uses variable stiffness elements, and sets the parameter adjustment rules of these variable stiffness elements according to different frequency ranges; when the node stiffness is expected to be larger in the low frequency band to ensure structural stability, it is achieved through appropriate control measures; when vibration isolation and force transmission reduction are required in the high frequency band, the stiffness is reduced accordingly; S4: Structural addition: Use a standard mandrel sample, and then use secondary addition around the mandrel to obtain different mandrel shape structures, where the mandrel shape structure can be achieved by adjusting the height, width and angle of the secondary addition structure in the longitudinal and vertical directions; the secondary addition methods include injection molding, secondary vulcanization, welding, bonding, etc.; Further, injection molding: injection molding secondary molding is a molding process in which a certain raw material is placed in an injection molding mold and a plastic is injected. Injection molding is used to add polymer materials (such as nylon, polytetrafluoroethylene, etc.) in the longitudinal and vertical directions of the standard mandrel to form different shape structures and achieve different longitudinal and lateral stiffness adjustments; Secondary vulcanization: Use simple vulcanization molds in the longitudinal and transverse directions of the standard mandrel to vulcanize the rubber material onto the mandrel, with different internal structures, so as to achieve different longitudinal and transverse stiffness adjustments; Welding: Welding is used in the longitudinal and transverse directions of the standard mandrel to weld metal materials of the same material to the mandrel, which can quickly complete different structural adjustments and stiffness verification; Bonding: Use glue (AB glue, Loctite glue, etc.) to bond parts of different materials and shapes to the standard mandrel in the longitudinal and transverse directions to form different mandrel results and achieve rapid adjustment of different longitudinal and transverse stiffness; Furthermore, the secondary addition structure is as follows: By adjusting the A dimension and ensuring that the lagging dimension C is a fixed value, usually 1~4mm, the hard stop function of different gaps H can be achieved in the longitudinal direction; The longitudinal stiffness of the product can be adjusted by the A dimension. When the A dimension increases, the longitudinal hard stop gap H decreases, and vice versa. The vertical stiffness can be adjusted by the B dimension. When the B dimension increases, the vertical stiffness also increases, and vice versa. The axial stiffness can be adjusted by adjusting the dimensions of E, F, and G. When the dimension E increases and the dimension F and angle G decrease, the lateral stiffness increases, and vice versa. S5: Experimental verification: The steps of experimental verification include: S5.1: Experimental sample preparation; S5.2: Set up experimental equipment; S5.3: Static characteristics test; S5.4: Data analysis; S5.5: Reliability and repeatability verification; The specific experimental steps are as follows: according to the designed frequency-variable stiffness arm node structure, the physical sample of the arm node is accurately processed and manufactured to ensure that its dimensional accuracy and surface quality meet the design requirements, and to ensure that the installation position of these components is accurate, the connection is reliable, and its own performance is stable. For the conventional components in the arm node, strict quality inspection and dimensional verification are carried out to avoid the accuracy of the experimental results affected by processing errors; Select a suitable vibration table or exciter to apply excitation forces of different frequencies. The frequency range should be able to cover the expected working frequency range of the swing arm node, and the excitation force can be precisely adjusted and controlled with sufficient accuracy and stability. Install the displacement sensor at the key position of the swing arm node to measure the displacement response of the swing arm under different frequency excitations. The measurement accuracy should be able to meet the experimental requirements to accurately capture small displacement changes and ensure the accuracy of force measurement. The error is controlled within a small range, such as the general accuracy can reach within 0.5% of the full scale. By slowly applying static force to the arm node, using force sensors and displacement sensors to measure the corresponding displacement under different static forces, the stiffness value of the arm node in static state is calculated, which is used as the basic data for subsequent dynamic experimental comparison and analysis; In order to ensure the reliability of the experimental results, after completing the above experiments, some experimental conditions can be changed or a newly manufactured swing arm node sample of the same specification can be replaced, and the above experimental process can be repeated to observe whether the obtained frequency-dependent stiffness curve and related experimental conclusions are consistent. If the results of multiple experiments have good repeatability and stability, then the effectiveness and reliability of the stiffness matching method and swing arm node design can be more powerfully demonstrated.

[0018] What is described above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A stiffness matching method for a frequency-variable stiffness swing arm node, which obtains different longitudinal, vertical, and transverse stiffnesses and a lower longitudinal and transverse stiffness ratio by adding different structures in the longitudinal and vertical directions of the core shaft of the liquid rubber composite node; characterized in that: The steps include: S1: Establishing the mechanical model: Based on the actual geometric shape, material properties and connection form of the swing arm node, the accurate mechanical model is established by applying the knowledge of theoretical mechanics, material mechanics and structural dynamics; S2: Modal analysis: Perform modal analysis on the established model to determine its natural frequency and vibration mode. By solving the eigenvalue problem, the natural frequencies of different orders and the corresponding vibration modes are obtained; S3: Determine stiffness matching: Based on the analysis in S1 and S2 and the desired frequency-dependent stiffness target, formulate a stiffness matching strategy and then add the physical structure; S4: Structural addition: Use a standard mandrel sample, and then use secondary addition around the mandrel to obtain different mandrel shape structures. The mandrel shape structure can be achieved by adjusting the height, width and angle of the secondary addition structure in the longitudinal and vertical directions; S5: Experimental verification: The steps of experimental verification include: S5.1: Experimental sample preparation; S5.2: Set up experimental equipment; S5.3: Static characteristics test; S5.4: Data analysis; S5.5: Reliability and repeatability verification.

2. The method for matching the stiffness of a frequency-variable stiffness swing arm node according to claim 1, characterized in that: The stiffness matching strategy in S3 adopts variable stiffness elements, and parameter adjustment rules of these variable stiffness elements are set according to different frequency ranges.

3. The stiffness matching method of a frequency-variable stiffness swing arm node according to claim 1, characterized in that: The secondary addition method in S4 includes injection molding, secondary vulcanization, welding, bonding, etc.

4. The method for stiffness matching of a frequency-variable stiffness swing arm node according to claim 1, characterized in that: Among them, the injection secondary molding puts the raw materials into the injection molding mold, injects a plastic molding process, and uses injection molding to add polymer materials for a second time in the longitudinal and vertical directions of the standard core shaft to form different external structures, so as to achieve different longitudinal and lateral stiffness adjustments. Secondary vulcanization: a simple vulcanization mold is used in the longitudinal and lateral directions of the standard core shaft to vulcanize the rubber material onto the core shaft, and the internal structure of different shapes is formed to achieve different longitudinal and lateral stiffness adjustments; welding: welding is used in the longitudinal and lateral directions of the standard core shaft to weld metal materials of the same material to the core shaft, which can quickly complete different structural adjustments and stiffness verifications; bonding: glue bonding is used in the longitudinal and lateral directions of the standard core shaft to bond components of different materials and shapes to the core shaft to form different core shaft results, so as to achieve different longitudinal and lateral stiffness Quick adjustment.

5. The method for matching the stiffness of a frequency-variable stiffness swing arm node according to claim 4, characterized in that: The secondary addition structure in S4 is specifically as follows: By adjusting the A dimension and ensuring that the lagging dimension C is a fixed value, usually 1~4mm, the hard stop function of different gaps H can be achieved in the longitudinal direction; The longitudinal stiffness of the product can be adjusted by the A dimension. When the A dimension increases, the longitudinal hard stop gap H decreases, and vice versa. The vertical stiffness can be adjusted by the B dimension. When the B dimension increases, the vertical stiffness also increases, and vice versa. The axial stiffness can be adjusted by adjusting the dimensions of E, F, and G. When dimension E increases and dimension F and angle G decrease, the lateral stiffness increases, and vice versa.

6. The method for stiffness matching of a frequency-variable stiffness swing arm node according to claim 1, characterized in that: The experimental steps of S5 are as follows: according to the designed frequency-variable stiffness swing arm node structure, the physical sample of the swing arm node is accurately processed and manufactured to ensure that its dimensional accuracy, surface quality, etc. meet the design requirements, ensure that the installation position of these components is accurate, the connection is reliable, and its own performance is stable, and the conventional components in the swing arm node are strictly inspected for quality and dimensioned to avoid affecting the accuracy of the experimental results due to processing errors; Select a suitable vibration table or exciter to apply excitation forces of different frequencies. The frequency range should be able to cover the expected working frequency range of the swing arm node, and the excitation force can be precisely adjusted and controlled with sufficient accuracy and stability. Install the displacement sensor at the key position of the swing arm node to measure the displacement response of the swing arm under different frequency excitations. The measurement accuracy should be able to meet the experimental requirements to accurately capture small displacement changes and ensure the accuracy of force measurement. The error is controlled within a small range, such as the general accuracy can reach within 0.5% of the full scale. By slowly applying static force to the arm node, using force sensors and displacement sensors to measure the corresponding displacement under different static forces, the stiffness value of the arm node in static state is calculated, which is used as the basic data for subsequent dynamic experimental comparison and analysis; In order to ensure the reliability of the experimental results, after completing the above experiments, some experimental conditions can be changed or a newly manufactured swing arm node sample of the same specification can be replaced, and the above experimental process can be repeated to observe whether the obtained frequency-dependent stiffness curve and related experimental conclusions are consistent. If the results of multiple experiments have good repeatability and stability, then the effectiveness and reliability of the stiffness matching method and swing arm node design can be more powerfully demonstrated.

7. A stiffness matching structure of a frequency-variable stiffness swing arm node, characterized in that: The invention comprises a symmetrically arranged left-hand arm outer sleeve (1) and a right-hand arm outer sleeve (2) and a symmetrically arranged left-hand arm inner sleeve (3) and a right-hand arm inner sleeve (4); a core shaft (5) is provided inside the left-hand arm inner sleeve (3) and the right-hand arm inner sleeve (4); liquid rubber (6) is provided between the core shaft (5) and the inner walls of the left-hand arm inner sleeve (3) and the right-hand arm inner sleeve (4); an inclined surface structure (7) is provided on the outer surface of the core shaft (5) and inside the left-hand arm inner sleeve (3) and the right-hand arm inner sleeve (4); and the thickness of the liquid rubber (6) on the left and right sides of the core shaft (4) is smaller than the thickness of the liquid rubber (6) on the upper and lower sides.

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