CN115111507B - Vibration isolation platform of accurate zero rigidity of extension with adjustable - Google Patents
Vibration isolation platform of accurate zero rigidity of extension with adjustable Download PDFInfo
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- CN115111507B CN115111507B CN202110291323.0A CN202110291323A CN115111507B CN 115111507 B CN115111507 B CN 115111507B CN 202110291323 A CN202110291323 A CN 202110291323A CN 115111507 B CN115111507 B CN 115111507B
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16M—FRAMES, CASINGS OR BEDS OF ENGINES, MACHINES OR APPARATUS, NOT SPECIFIC TO ENGINES, MACHINES OR APPARATUS PROVIDED FOR ELSEWHERE; STANDS; SUPPORTS
- F16M11/00—Stands or trestles as supports for apparatus or articles placed thereon ; Stands for scientific apparatus such as gravitational force meters
- F16M11/20—Undercarriages with or without wheels
- F16M11/24—Undercarriages with or without wheels changeable in height or length of legs, also for transport only, e.g. by means of tubes screwed into each other
- F16M11/38—Undercarriages with or without wheels changeable in height or length of legs, also for transport only, e.g. by means of tubes screwed into each other by folding, e.g. pivoting or scissors tong mechanisms
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F15/00—Suppression of vibrations in systems; Means or arrangements for avoiding or reducing out-of-balance forces, e.g. due to motion
- F16F15/02—Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems
- F16F15/04—Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems using elastic means
- F16F15/08—Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems using elastic means with rubber springs ; with springs made of rubber and metal
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16M—FRAMES, CASINGS OR BEDS OF ENGINES, MACHINES OR APPARATUS, NOT SPECIFIC TO ENGINES, MACHINES OR APPARATUS PROVIDED FOR ELSEWHERE; STANDS; SUPPORTS
- F16M11/00—Stands or trestles as supports for apparatus or articles placed thereon ; Stands for scientific apparatus such as gravitational force meters
- F16M11/02—Heads
- F16M11/04—Means for attachment of apparatus; Means allowing adjustment of the apparatus relatively to the stand
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Aviation & Aerospace Engineering (AREA)
- Vibration Prevention Devices (AREA)
Abstract
The invention relates to the technical field of vibration isolation in engineering, in particular to an adjustable vibration isolation platform with enlarged quasi-zero rigidity. The adjusting device can twist the nut in a labor-saving mode through a gear amplifying torque system, so that the pre-pressure of the horizontal spring is adjusted; the U-shaped elastic structure does not work in a certain horizontal movement range, and when the movement amplitude is increased or the load is increased, the horizontal spring in the U-shaped structure is contacted with the bottom support, so that positive rigidity which is gradually increased from zero is generated; the whole X-shaped vibration isolation platform can realize favorable nonlinear rigidity and damping, particularly, the platform can generate quasi-zero rigidity and even negative rigidity under a certain load, the stability of the structure is unfavorable, the vibration isolation performance is reduced, and the U-shaped elastic structure device can provide a rigidity curve from zero rigidity to positive rigidity in the vertical direction.
Description
Technical Field
The invention relates to the technical field of vibration isolation, in particular to a vibration isolation device and a platform based on adjustable nonlinear stiffness damping of a bionic structure, widened quasi-zero stiffness range and labor-saving adjustment of gear drive.
Background
The statements herein merely provide background information related to the present disclosure and may not necessarily constitute prior art.
In engineering, vibration isolation platforms are widely applied, such as suspension systems of automobile seats, vibration isolation platforms of precise instruments in mechanical systems and vibration isolation layer designs of structures in civil engineering, and the vibration isolation systems can be applied to civil fields and can be applied to vibration protection in aerospace military fields such as aircrafts, ships, missile launching and the like under optimal design.
The vibration isolation field has the vibration isolation modes of passive vibration isolation, active vibration isolation, semi-active vibration isolation and the like. The passive vibration isolation technology has no energy consumption, does not need to use devices such as a sensor, a controller and the like, does not depend on real-time monitoring, and is safe, stable and low in cost. Under the optimal design, the passive vibration isolation technology can realize the effect of active vibration isolation and can be widely used.
Vibration isolation systems can be classified into linear vibration isolation systems and nonlinear vibration isolation systems from mathematical modeling analysis. The linear system dynamics model is simple and easy to analyze, but has limitation that some vibration mechanisms cannot be deeply analyzed, and meanwhile, beneficial phenomena possibly brought by nonlinear terms are ignored. Although modeling of a nonlinear system is complex, analysis has difficulty, but the nonlinear system has the advantage that the nonlinear system cannot be realized, for example, the nonlinear phenomenon of the system can be deeply analyzed, and more advantageous product performance and structural design are realized by utilizing the nonlinear phenomenon in engineering, for example, the vibration isolation performance of the system is improved by utilizing nonlinearity.
For increasingly higher vibration isolation requirements, such as low frequency vibration isolation, wider vibration isolation frequency ranges, minimum resonance peaks, etc., the stiffness and damping of the vibration isolation system need to be optimally designed to achieve optimal vibration isolation. In the parameter design of a linear vibration isolation system, the system rigidity is reduced to realize low-frequency vibration isolation, and meanwhile, the vibration isolation frequency band is widened, but the bearing capacity of a vibration isolation platform is reduced; an increase in the damping coefficient reduces the vibration amplitude of the formants, but deteriorates the vibration isolation performance in the high frequency region, which are problems that the linear system cannot solve.
In contrast, the nonlinear vibration isolation system under the optimal design can solve the problems, and the omnibearing vibration isolation performance of the whole system is improved. For example, geometric nonlinearity of the structure can be used to design ultra-low dynamic stiffness while improving static bearing capacity, namely: the nonlinear rigidity of high static rigidity and low dynamic rigidity (high static and low dynamic) can even realize quasi-zero rigidity, and the vibration isolation system can realize ultralow frequency vibration isolation, more than 1Hz effective vibration isolation and even full frequency vibration isolation. However, some of the existing quasi-zero stiffness technologies also have some problems, such as over-narrow range of quasi-zero stiffness, instability, and the like, and further optimization design is needed to solve the problems.
Disclosure of Invention
The invention aims to provide an adjustable and widened vibration isolation device with a quasi-zero stiffness range, and aims to solve the technical problems of over-narrow quasi-zero stiffness range, unstable motion, poor bearing capacity, difficult parameter adjustment and the like of a passive vibration isolation device in the prior art.
In order to achieve the above purpose, the technical scheme of the invention is as follows:
The invention provides an adjustable vibration isolation platform for expanding quasi-zero rigidity, which comprises the following components:
The X-shaped vibration isolation platform comprises an X-shaped structure, an upper platform and a base, wherein the top of the X-shaped structure is connected with the upper platform, and the bottom of the X-shaped structure is connected with the base;
the adjusting device is connected with the X-shaped structure and drives the X-shaped structure to lift; the pre-tightening force of the horizontal spring is regulated, so that the upper platform can be lifted and lowered, the vertical rigidity of the X-shaped structure is provided, and positive, negative or zero rigidity can be respectively realized through the regulating device;
the U-shaped elastic structure comprises a U-shaped interface, a spring and a bottom support; the non-interface position of the U-shaped interface is fixed on the upper platform, and the spring is horizontally arranged in the U-shaped interface; the bottom support is arranged on the base, and when the spring is contacted with the base support, the horizontal spring generates stretching deformation, so that positive rigidity in the vertical direction is provided for the system.
As a further technical scheme, the adjusting device is an automatic driving device or a manual driving device.
As a further technical scheme, the automatic driving device comprises a motor and a gear transmission system connected with the motor, and the labor-saving adjusting function is realized through a gear set.
As a further technical scheme, the manual driving device comprises a rotary handle and a gear transmission system connected with the handle.
As a further technical scheme, the bottom support comprises a fixing clamp, the upper part of the fixing clamp clamps a clamping piece, and the relative position of the clamping piece and the fixing clamp in the height direction is adjustable.
As a further technical scheme, a first shaft and a second shaft are arranged at the bottom of the X-shaped structure, the second shaft is connected with a nut, and the first shaft is fixed on the base and can rotate; the nut is matched with the threaded rod, and the adjusting device drives the threaded rod to rotate.
As a further technical scheme, the X-shaped structure further comprises a horizontal spring, one end of the horizontal spring is connected with the nut, and the other end of the horizontal spring is connected with the first shaft at the bottom of the X-shaped structure.
As a further technical scheme, the base comprises an outer frame, and the outer frame is provided with a sliding groove matched with the first shaft and a fixed end for fixing the second shaft.
The adjusting device can twist the nut in a labor-saving mode through a gear amplifying torque system, so that the pre-pressure of the horizontal spring is adjusted; the U-shaped elastic structure does not work in a certain horizontal movement range, and when the movement amplitude is increased or the load is increased, the horizontal spring in the U-shaped structure is contacted with one bottom support of the bottom, so that positive rigidity which is gradually increased from zero is generated; the X-shaped vibration isolation platform consists of an upper platform, a base and an X-shaped structure, wherein the X-shaped structure consists of a rotating rod, a bearing, a shaft, a horizontal elastic piece and the like. The whole X-shaped vibration isolation platform can realize favorable nonlinear rigidity and damping, particularly, the X-shaped vibration isolation platform can generate quasi-zero rigidity and even negative rigidity under a certain load, the stability of the structure is unfavorable, the vibration isolation performance is reduced, and the U-shaped elastic structure device can provide a rigidity curve from zero rigidity to positive rigidity in the vertical direction. Through the optimal design, the negative rigidity of the X-shaped structure and the positive rigidity of the U-shaped elastic structure can be mutually offset, so that a widened quasi-zero rigidity range is realized, and meanwhile, the synthesized rigidity curve is a smooth curve.
Compared with the existing structure, the invention has the following innovation:
(1) The rigidity adjusting device of the system adopts a gear transmission system, so that the adjusting process is more labor-saving, and two adjusting modes of motor driving or manual driving can be adopted.
(2) The design of the gear system utilizes the relation of force transmission and torque transmission between gears to amplify the input torque to the output torque, and the amplification effect can be from several times to hundreds of times. This magnification can be determined by the design of the gear dimensions.
(3) The design of U type elastic construction is in order to widen the quasi-zero rigidity scope of system, improve vibration isolation performance, increase stability, specifically, when X type structure compression or motion amplitude reach certain degree, thereby U type elastic construction and bottom support contact produce spring pulling force, provide a positive rigidity that slowly increases from the beginning for the system, thereby offset X type structure negative rigidity this moment, make quasi-zero rigidity scope widen, U type elastic core effect is with X type structure's rigidity coupling, produce a smooth continuous rigidity curve and have widened quasi-zero rigidity scope simultaneously.
(4) The U-shaped elastic structure can generate gradually increased positive rigidity after being contacted with the bottom support, so that the bearing capacity of the system is improved, and the problem that the negative rigidity of the X-shaped structure is unstable and can collapse under large load and large amplitude is solved.
Drawings
FIG. 1 is an overall design framework of the present invention;
FIG. 2 is a design framework of a gear amplification system;
FIG. 3 is a diagram of a model design of the present invention;
FIG. 4 (a) stiffness curve for an X-type structure; FIG. 4 (b) stiffness curve for coupling X-type structure to U-type elastic structure; FIG. 4 (c) vibration transmissivity at different operating positions;
FIG. 5 (a) is an expanded quasi-zero stiffness curve under optimized coupling of the present invention; FIG. 5 (b) vibration transmissivity of the present invention at various operating positions after optimization;
FIG. 6 is a schematic diagram of a three-dimensional model of a motor drive of the present invention;
FIG. 7 is a schematic representation of a manually driven three-dimensional model of the present invention;
FIG. 8 is a cross-sectional view of a manual drive of the present invention;
FIG. 9 is a front view of a manually driven three-dimensional model of the invention;
FIG. 10 is a side view of a manually driven three-dimensional model of the invention;
FIG. 11 is a top view of a manually driven three-dimensional model of the present invention;
FIG. 12 is a front view of a motor-driven three-dimensional model of the present invention;
FIG. 13 is a side view of a three-dimensional model of the motor drive of the present invention;
FIG. 14 is a top view of a motor-driven three-dimensional model of the present invention;
FIG. 15 is a schematic diagram of a gear system of the present invention;
FIG. 16 is a schematic view of the structure of the bottom support of the U-shaped elastic structure of the present invention;
fig. 17 is a schematic structural view of an X-type vibration isolation platform according to the present invention;
fig. 18 is a schematic view of a base of an X-vibration isolation platform according to the present invention
In the figure:
10 adjusting device, 111 motor drive, 112 manual drive, 121 input pinion, 122 amplifying gear, 123 coaxial pinion, 124 output gear;
20 The U-shaped elastic structure, a 21U-shaped interface, a 22 horizontal spring and a 23 bottom support;
30X-type vibration isolation platform, 31X-type structure, 32 mechanical device,
311 Rotating rod, 312 shaft, 313 bearing, 314 horizontal elastic piece;
3121 a first axis, 3122 a second axis, 3123 other axes;
321 upper platform, 322 base;
3211X-shaped structure fixed end, 3212 sliding groove and 3213 outer frame;
3221X-shaped structure fixed end, 3222 sliding groove and 3223 outer frame.
Detailed Description
It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the invention. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the present invention. As used herein, the singular forms also are intended to include the plural forms unless the present invention clearly dictates otherwise, and furthermore, it should be understood that when the terms "comprise" and/or "include" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof;
for convenience of description, the words "upper", "lower", "left" and "right" in the present invention, if they mean only the directions of upper, lower, left and right in correspondence with the drawings themselves, are not limiting in structure, but merely serve to facilitate description of the present invention and simplify description, rather than to indicate or imply that the apparatus or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention.
The terms "mounted," "connected," "secured," and the like are to be construed broadly and refer to either a fixed connection, a removable connection, or an integral body, for example; can be directly connected or indirectly connected through an intermediate medium, can be internally connected or interacted with each other, the above terms are understood in the specific meaning of the present invention according to circumstances, for those of ordinary skill in the art.
As introduced by the background technology, the invention provides an adjustable vibration isolation platform with enlarged quasi-zero rigidity, which can realize adjustable rigidity and damping characteristics, labor-saving adjustment mode and widened quasi-zero rigidity range and favorable nonlinear rigidity damping, so that the vibration isolation device can realize ultralow frequency vibration isolation, wider effective vibration isolation range, better stability and stronger bearing capacity.
The embodiment discloses an adjustable vibration isolation platform with enlarged quasi-zero rigidity, which mainly comprises an adjusting device, a U-shaped elastic structure and an X-shaped vibration isolation platform. According to the adjusting device, a labor-saving mode for adjusting the rigidity of the system is realized through the gear transmission system; the designed U-shaped elastic structure is used for adding additional equivalent positive rigidity and coupling with the negative rigidity of the X-shaped structure, so that a wider quasi-zero rigidity range is created, and meanwhile, the structural stability is improved.
Further, the adjusting device in the present embodiment is divided into two types, a motor drive 111 and a manual drive 112. The motor driving manner disclosed in this embodiment is shown in fig. 6, 13, 14 and 15, wherein the motor driving manner is to mount the input pinion 121 on the motor output bearing, and when the motor is started, the input pinion 121 starts to rotate and drives the amplifying gear 122 to rotate; the amplifying gear 122 and the coaxial pinion 123 are simultaneously fixed at both ends of one shaft, respectively, and the output torque is amplified by the size ratio of the two gears; the coaxial pinion 123 rotates while driving the output gear 124 to rotate, and finally amplifies the output torque.
As shown in fig. 7, 8, 9, 10, and 11, the manual driving method disclosed in the present embodiment is different from the motor driving method in that the amplifying gear 122 is replaced by a disc, the motor and the input pinion 121 are omitted, the disc is directly rotated by hand, and the gear system is driven, so that the output torque is finally amplified.
Specifically, two modes of motor driving or manual driving can be selected according to actual requirements, and then a gear system is designed, including selecting the size, the diameter and the like of each gear, for example, in the embodiment, the diameter ratio of the gears is selected as follows: amplification gear 122: input pinion 121=2, coaxial pinion 123: amplification gear 122=1/2, output gear 124: with coaxial pinion 123=2, the gear system can amplify the input torque by a factor of 4, i.e., four times the input torque when outputting torque.
Based on the gear system, the adjusting device can amplify the torque to realize a labor-saving mode to twist the nut, so that the pre-pressure and the pre-pressure of the horizontal spring and the equivalent stiffness of the system are adjusted.
The design of the U-shaped elastic structure in the embodiment is to increase the positive rigidity of the system, and the coupling effect of the U-shaped elastic structure and the X-shaped structure further widens the quasi-zero rigidity range of the system and improves the stability of the system. As shown in fig. 8, the U-shaped elastic structure includes the U-shaped interface 21, a horizontal spring 22, and a bottom support 23.
Further, the design of the U-shaped interface 21 in this embodiment is to install the horizontal spring 22, and the size needs to be matched with the horizontal spring 22 during the design, one end of the U-shaped interface 21 is fixed on the upper mechanical device 321, and the U-shaped interface 21 installs the horizontal spring 22, so that the installation position is required to be adjustable, and the horizontal distance and position of the horizontal spring 22 are enabled to be adjustable.
The horizontal spring 22 in this embodiment is an elastic element, and can have a large elastic deformation, and is not particularly limited to a spring, and in this example, a spring is selected as an example. The rigidity, length, coil diameter and other parameters of the horizontal spring 22 can be selected according to requirements, and meanwhile, the rigidity of the X-shaped structure is matched to select proper parameters. Further, the horizontal spring 22 may be made of elastic silica gel, rubber, or the like. Meets a certain elastic modulus and the stretching length.
The bottom support 23 in this embodiment is adapted to contact the horizontal spring 22 such that the horizontal spring 22 is stretched to provide positive stiffness in the vertical direction to the system.
Further, the height of the bottom support 23 is adjustable, after calculation and analysis, the height of the bottom support is selected, and when the X-shaped structure is compressed to a certain position, the top end of the bottom support 23 contacts with the spring 22, triggering contact deformation and generating rigidity.
Further, the bottom support 23 in this example is designed as a bottom fixture to fit a porous clip. The porous design is to adjust the installation position conveniently, and further meet the requirement of the height-adjustable bottom support 23, and the specific structure is shown in fig. 16, which includes a fixing clamp, a clamping piece is installed on the fixing clamp, and a plurality of holes are formed in the clamping piece.
In this embodiment, the X-type vibration isolation platform 30 is composed of the X-type structure 31 and the mechanical device 32, and is a main structure of the present invention.
As shown in fig. 17, the X-shaped structure 31 is composed of a plurality of rotating rods 311, a plurality of shafts 312, a plurality of bearings 313 and a horizontal elastic member 314; in the embodiment, the number of the rotating rods 311 is 8, the 8 rotating rods are arranged in two groups, one group is provided with 4 rotating rods, and the two groups are symmetrical front and back; taking one group as an example, two of the four rotating rods 311 are arranged above in a crossing manner, the other two rotating rods 311 are arranged below in a crossing manner, and the crossing positions and the end parts of the rotating rods 311 arranged above and below in a crossing manner are connected with the other group of rotating rods through the shaft 312 and the bearing 313.
The X-shaped structure 31 is characterized in that the motion in the horizontal direction is converted into the motion in the vertical direction having the geometric nonlinearity by the motion among the rotating rod 311, the shaft 312 and the bearing 313, and in particular, the rotating rod 311 rotates when the vibration isolation platform moves by the connection of the shaft 312 and the bearing 313, so that the bottom end of the rotating rod 311 performs the horizontal motion, and the horizontal motion has a geometric nonlinearity relationship with the vertical motion of the upper platform 321 of the X-shaped vibration isolation platform, thereby optimizing the vibration isolation performance of the X-shaped vibration isolation platform by using the nonlinearity relationship.
The shaft 312 is composed of a first shaft 3121 at the bottom and top, a second shaft 3122, and other shafts 3123. The second shaft 3122 at the bottom of the X-shaped structure is fixed on the nut, the nut is matched with the threaded rod, the adjusting device (the motor drive 111 and the manual drive 112) drives the threaded rod to rotate, the adjusting device drives the threaded rod to rotate, the threaded rod drives the nut to horizontally move, and then the direction of the second shaft first shaft at the bottom of the X-shaped structure is close to or far away from, so that the whole X-shaped structure is lifted or lowered.
The horizontal spring 314 provides a horizontal stiffness to the X-shaped structure 31, and when the X-shaped structure 31 moves, the horizontal spring 314 stretches or compresses to provide a recoverable elastic potential energy to the system.
In this embodiment, the horizontal elastic member 314 is a spring, one end of the spring is connected to the nut, and the other end is connected to the first shaft 3121, and the first shaft is fixed on the base and can rotate;
Further, the equivalent stiffness of the X-shaped structure will generate quasi-zero stiffness after the structure is compressed to a certain extent or the vibration amplitude exceeds a certain extent, then generate negative stiffness, and the negative stiffness is counteracted by matching with the positive stiffness of the U-shaped elastic structure 20, so that the interval of the quasi-zero stiffness of the whole system is widened, and the bearing capacity is greatly improved.
The mechanical device 32 in this embodiment includes an upper platform 321 and a base 322, which are connected to mount an X-shaped structure, so that the shaft 312 of the X-shaped structure can slide horizontally, and the rotating rod rotates around the shaft, so that the horizontal movement is finally converted into the vertical movement.
Further, the top layer of the upper platform 321 is provided with an object to be isolated, the connection plate of the top layer fixes the U-shaped elastic structure 20, and the U-shaped elastic structure 20 moves along the upper platform 321 in the vertical direction; the upper platform 321 comprises an X-shaped structure fixed end 3211, a sliding groove 3212 and an outer frame 3213; the X-shaped structure fixed end 3211 of the outer frame 3213 is used for fixing
The bottom of the bottom support 322 is connected with a foundation or a vibrating table, and a connecting plate at the bottom of the bottom support is used for fixing the bottom support 23 of the U-shaped spring of the U-shaped elastic structure 20. The bottom support 322 includes an X-shaped structure fixed end 3221, a sliding groove 3222, and an outer frame 3223.
The U-shaped elastic structure 20 is coupled with the X-shaped vibration isolation platform 30 to function: the X-type vibration isolation platform 30 can realize favorable nonlinear rigidity and damping to achieve a better vibration isolation effect, but the X-type vibration isolation platform 30 can have quasi-zero rigidity under a certain load so as to have negative rigidity, which is disadvantageous to the stability of the structure, and the U-type elastic structure 20 device can provide a rigidity curve from zero rigidity to positive rigidity in the vertical direction. Through the optimal design, when the negative rigidity of the X vibration isolation platform 20 appears, the negative rigidity and the positive rigidity of the U-shaped elastic structure 20 can be mutually offset, so that a widened quasi-zero rigidity range is realized, and meanwhile, the synthesized rigidity curve is a smooth curve.
Embodiments of the invention: the design and assembly of the adjustable vibration isolation platform with enlarged quasi-zero rigidity comprise the following steps:
s1: firstly, designing the size scale of a platform according to actual needs, and selecting the number of layers n of an X-shaped structure and the length L of a rotating rod used by the structure according to the required size;
S2: the X-shaped structure is installed and fixed on the upper platform and the base by using a bearing or a hinge;
S3: optimizing the rigidity required by an analysis system according to the requirements of bearing capacity and vibration isolation performance, and selecting the length, elastic modulus and the like of a proper horizontal elastic piece;
S4: the selected horizontal elastic piece is installed, connected and placed at the bottom of the X-shaped structure, one end of the horizontal elastic piece is connected with the rotating shaft, and the nut is fixed at one end of the horizontal elastic piece;
S5: the gear is selected according to the requirement, a gear transmission system is installed, the center of an input pinion is fixed with a motor, the input pinion is connected with an amplifying gear to drive the amplifying gear to rotate, the center of the amplifying gear is fixedly connected with a shaft, the other end of the shaft is fixedly connected with the center of a coaxial pinion, the coaxial pinion drives an output large gear to rotate, the center of the output large gear is fixed with a threaded rod, and the other end of the threaded rod is matched with a nut in S4.
S6, if manual input is selected in the step S5, a motor and an input pinion are not needed, the amplifying gear is replaced by a rotating disc, and the rest steps are the same as the step S5;
S7: according to rigidity analysis, calculating the horizontal position of the U-shaped elastic structure and the height of the bottom support, and then installing a U-shaped interface on a top connecting plate of the X-shaped structure and installing a horizontal spring in the U-shaped structure;
S8: and calculating the contact horizontal height of the U-shaped elastic structure according to the requirements, adjusting the height of the bottom support, and then installing the bottom support of the U-shaped elastic structure on a connecting plate at the bottom of the X-shaped structure mechanical device.
S9: if necessary, the combination piece of the spring and the damper is used as a horizontal elastic piece to be placed and installed at the corresponding position of the X-shaped structure, so that the vibration reduction effect can be further enhanced;
According to the embodiment of the invention, the nonlinear stiffness damping of the X-shaped structure is utilized, the quasi-zero stiffness range is further widened by matching with the U-shaped elastic structure, the vibration isolation effect is improved, and meanwhile, a gear transmission system is used for realizing a labor-saving adjusting mode. The vibration isolation effect can be expressed by a vibration transmissibility defined as a ratio of a vibration amplitude of the vibration isolation object to an external excitation amplitude. Fig. 4 (a) and 4 (b) show the static stiffness curves of the system and the corresponding analysis of vibration isolation performance. Wherein fig. 4 (a) is a static stiffness curve of an X-shaped structure of the vibration isolation platform. It can be seen that as the static load increases, the X-shaped structure will exhibit a very narrow quasi-zero stiffness range and then enter the negative stiffness range. When negative stiffness occurs, the structure is now in an unstable state, resulting in collapse. Fig. 4 (b) is a static stiffness curve of an X-shaped structure coupled with a U-shaped elastic structure. After optimization analysis, a U-shaped elastic structure is installed, when the X-shaped structure has negative rigidity, the U-shaped elastic structure is contacted with the bottom support to generate positive rigidity in the vertical direction, and is coupled with the negative rigidity of the original X-shaped structure to form a new rigidity curve, as shown in fig. 4 (b), the quasi-zero rigidity range in the graph is enlarged, meanwhile, no negative rigidity occurs when the load is further increased, and the system is always in a stable state. The optimized static stiffness curve is a continuous smooth composite stiffness curve. Fig. 4 (c) shows vibration isolation performance corresponding to different working positions: vibration transfer rate curve. As shown in the figure, the working position C is the optimal working position, and the system is in a quasi-zero stiffness range, the amplitude of the resonance peak is minimum, and the vibration isolation frequency range is the widest.
Fig. 5 (a), 5 (b) further analyze this coupling stiffness effect: the positive rigidity in the vertical direction generated by the contact of the U-shaped elastic structure and the bottom support is coupled with the negative rigidity of the original X-shaped structure to form a new rigidity curve, as shown in fig. 5 (a), the quasi-zero rigidity range in the diagram is enlarged, no negative rigidity appears, and the system is always in a stable state when the load is further increased. Both C and D are in the quasi-zero stiffness range. Further, vibration isolation performance of the corresponding working position is calculated. Four positions A, B, C, D are selected in the static stiffness plot 5 (a). A. The transmissivities corresponding to B, C, D four operating positions are shown in fig. 5 (b). As shown in the figure, the amplitude of the transmissibility formant of the D is minimum, the effective vibration isolation frequency range is the widest, and the vibration isolation effect is the best. The appearance of D depends on the coupling action of the U-shaped elastic structure and the X-shaped structure, and the coupling action not only widens the range of quasi-zero rigidity, but also ensures that the structure can be kept stable under large-amplitude motion. The vibration isolation performance of D is superior to that of C, so that the coupling rigidity can widen the quasi-zero rigidity range, reduce the amplitude of resonance peaks and improve the sandwiching performance.
The invention has adjustable nonlinear characteristic, widened quasi-zero stiffness range and labor-saving adjusting mechanism. Firstly, a labor-saving adjusting mode can be realized through the design of a gear transmission system, and the spring of the X-shaped structure is adjusted to stretch, the length of compression is further adjusted to the equivalent rigidity of the X-shaped structure. Secondly, the coupling effect of the U-shaped elastic structure and the X-shaped structure can be utilized to realize a widened quasi-zero stiffness range, and meanwhile, the stability and the bearing capacity are improved. The ultra-low frequency vibration control can be realized through the optimal design, the ultra-wide effective vibration isolation frequency range is realized, the motion stability is good, and the static bearing capacity is strong. Meanwhile, the invention has the characteristics of small volume, heavy load, no energy consumption, environmental protection, low requirements on manufacturing and processing precision, low production cost and the like, and can be widely used for vibration reduction and vibration control of precise instruments, engineering structures and the like.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but any modifications, equivalents, or improvements made within the spirit and principles of the present invention should be included in the scope of the present invention.
The invention based on the X-shaped structure design has the following advantages and innovation points:
1. The adjusting device can realize a labor-saving mode of adjusting the horizontal spring pre-pressing and pre-stretching by utilizing the gear transmission system, thereby conveniently adjusting the equivalent stiffness, the natural frequency, the vibration isolation range and the like of the system.
2. The adjusting mode is two modes of motor driving and manual driving, and can be selected according to actual requirements. The motor drive can be further connected with an external controller, a computer and the like to realize remote control, and the manual drive has no energy consumption, and is convenient and low in cost.
The 3.U elastic structure can provide additional equivalent positive rigidity, and the time for generating the positive rigidity can be controlled by adjusting the height of the bottom support.
The 4.U type elastic structure force has a coupling effect with the X type structure spring force: through optimal design, the positive rigidity of the U-shaped elastic structure can offset the negative rigidity of the X-shaped structure, so that the quasi-zero rigidity range of the original X-shaped vibration isolation platform is widened, and meanwhile, the vibration isolation performance, the stability and the bearing capacity of the whole system are greatly improved.
Finally, it is pointed out that relational terms such as first and second are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (5)
1. An adjustable enlarged quasi-zero stiffness vibration isolation platform comprising:
The X-shaped vibration isolation platform comprises an X-shaped structure, an upper platform and a base, wherein the top of the X-shaped structure is connected with the upper platform, and the bottom of the X-shaped structure is connected with the base;
The adjusting device is connected with the X-shaped structure and drives the X-shaped structure to lift;
The U-shaped elastic structure comprises a U-shaped interface, a spring and a bottom support; the non-interface position of the U-shaped interface is fixed on the upper platform, and the spring is horizontally arranged in the U-shaped interface; the bottom support is arranged on the base, and when the spring is contacted with the base support, the spring generates tensile deformation to provide positive rigidity in the vertical direction for the system;
The bottom support comprises a fixed clamp, the upper part of the fixed clamp clamps a clamping piece, and the relative position between the clamping piece and the fixed clamp is adjustable in the height direction;
the bottom of the X-shaped structure is provided with a first shaft and a second shaft, the second shaft is connected with a nut, and the first shaft is fixed on the base and can rotate; the nut is matched with the threaded rod, and the adjusting device drives the threaded rod to rotate;
The device also comprises a horizontal spring, wherein one end of the horizontal spring is connected with the nut, and the other end of the horizontal spring is connected with a first shaft at the bottom of the X-shaped structure;
The threaded rod drives the nut to horizontally move, so that the direction of the second axial first axis at the bottom of the X-shaped structure is close to or far away from the direction of the second axial first axis, and the whole X-shaped structure is lifted or lowered;
The horizontal spring provides rigidity in the horizontal direction for the X-shaped structure, the equivalent rigidity of the X-shaped structure can generate quasi-zero rigidity after the structure is compressed to a certain degree or the vibration amplitude exceeds a certain degree, then negative rigidity is generated, positive rigidity of the U-shaped elastic structure is matched, the negative rigidity is counteracted, and the interval of the quasi-zero rigidity of the whole system is widened.
2. The adjustable amplified quasi-zero stiffness vibration isolation platform of claim 1 wherein,
The adjusting device is an automatic driving device or a manual driving device.
3. The adjustable vibration isolation platform with enlarged quasi-zero stiffness according to claim 2, wherein the automatic driving device comprises a motor and a gear transmission system connected with the motor, and the labor-saving adjusting function is realized through a gear set.
4. The adjustable amplified quasi-zero stiffness vibration isolation platform of claim 2 wherein said manual drive means comprises a rotary handle and a gear train coupled to the handle.
5. The adjustable amplified quasi-zero stiffness vibration isolation platform of claim 1 wherein said base includes an outer frame with a sliding slot for mating with the first shaft and a fixed end for securing the second shaft.
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