CN116164065B - Two-degree-of-freedom quasi-zero stiffness vibration isolator for polishing equipment - Google Patents

Two-degree-of-freedom quasi-zero stiffness vibration isolator for polishing equipment Download PDF

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Publication number
CN116164065B
CN116164065B CN202310172658.XA CN202310172658A CN116164065B CN 116164065 B CN116164065 B CN 116164065B CN 202310172658 A CN202310172658 A CN 202310172658A CN 116164065 B CN116164065 B CN 116164065B
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vibration isolator
platform
plate
connecting block
quasi
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CN116164065A (en
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王帅
辛大卫
卢文娟
王国庆
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Dongguan University of Technology
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Dongguan University of Technology
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Classifications

    • 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
    • F16F3/00—Spring units consisting of several springs, e.g. for obtaining a desired spring characteristic
    • F16F3/02—Spring units consisting of several springs, e.g. for obtaining a desired spring characteristic with springs made of steel or of other material having low internal friction
    • F16F3/04—Spring units consisting of several springs, e.g. for obtaining a desired spring characteristic with springs made of steel or of other material having low internal friction composed only of wound springs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B41/00—Component parts such as frames, beds, carriages, headstocks
    • B24B41/007—Weight compensation; Temperature compensation; Vibration damping
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B41/00—Component parts such as frames, beds, carriages, headstocks
    • B24B41/02—Frames; Beds; Carriages
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B55/00—Safety devices for grinding or polishing machines; Accessories fitted to grinding or polishing machines for keeping tools or parts of the machine in good working condition
    • 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
    • F16F2228/00—Functional characteristics, e.g. variability, frequency-dependence
    • F16F2228/06—Stiffness
    • 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
    • F16F2228/00—Functional characteristics, e.g. variability, frequency-dependence
    • F16F2228/06—Stiffness
    • F16F2228/063—Negative stiffness

Abstract

The application relates to a two-degree-of-freedom quasi-zero stiffness vibration isolator for polishing equipment, which comprises a center platform, a support column, a base, a torsion spring group and a planar 2-RRR parallel mechanism. The plane 2-RRR parallel mechanism comprises a connecting block, first plate pieces respectively arranged on two end parts of the connecting block, and a bottom plate arranged opposite to the connecting block, wherein the second plate pieces and the bottom plate are sequentially hinged through a rotating shaft to form a closed-loop plane parallel mechanism, and the bottom plate is connected with a base; the connecting block is hinged with the connecting rod by a pin shaft, the central platform drives the connecting rod, the connecting rod drives the connecting block, and a torsion spring is arranged at the middle part of a rotating shaft connected with the second plate and the bottom plate. When in the singular configuration, provides negative stiffness to the vibration isolation mechanism. The application utilizes the combination of positive and negative rigidity to construct a quasi-zero rigidity mechanism, can reduce the dynamic rigidity of the vibration isolator in the axial direction and the circumferential direction of polishing equipment, has lower initial vibration isolation frequency and resonance peak value, and realizes better low-frequency vibration isolation effect.

Description

Two-degree-of-freedom quasi-zero stiffness vibration isolator for polishing equipment
Technical Field
The application relates to the technical field of low-frequency vibration isolation, in particular to a two-degree-of-freedom quasi-zero stiffness vibration isolator for polishing equipment.
Background
When complex processes such as polishing, grinding and weld grinding are performed in workshops, many harmful multidimensional low-frequency vibrations are often generated due to the operation of large surrounding instruments and the fluctuation of equipment. The main coverage range of the disturbance vibration spectrum is 0.1-10_Hz, and larger vibration acceleration and amplitude can be generated, so that the machining precision can be reduced, the service life of equipment can be influenced when the machining precision is serious, and precision equipment is damaged. Traditional linear spring-damping vibration isolation systems can only isolate medium and high frequency vibrations greater than 10Hz, but when subjected to low frequency disturbances, they can amplify the low frequency disturbances due to resonance. The concept of a quasi-zero stiffness vibration isolation system is therefore emerging to address low frequency disturbances.
The quasi-zero stiffness vibration isolation system consists of a positive stiffness elastic element and a negative stiffness mechanism which are connected in parallel. And the rigidity correction is carried out by adopting a negative rigidity mechanism, so that the rigidity of a terminal platform of the vibration isolation system is reduced when the vibration isolator moves within a proper static balance position range, and the natural frequency and resonance peak value of the vibration isolator under the same bearing capacity are reduced, thereby realizing better low-frequency vibration control. However, at present, research on a low-frequency vibration isolator for realizing the multi-dimensional direction at the same time is still in a primary stage, and a single-degree-of-freedom vibration isolator is mostly adopted as each branch of a parallel mechanism to realize the multi-dimensional direction vibration isolation, but the method can complicate the structure of the vibration isolator and enlarge the volume. Meanwhile, the coupling effect among the branch vibration isolators cannot be avoided, and the vibration isolators have the problems of larger initial vibration isolation frequency and smaller vibration isolation interval, so that the low-frequency vibration isolation performance is reduced.
Disclosure of Invention
The application provides a two-degree-of-freedom quasi-zero stiffness vibration isolator for polishing equipment, which aims to solve the problems that the structure of the existing multi-dimensional direction vibration isolator is complex and the coupling effect between branch vibration isolators is serious, realize the low-frequency vibration isolation of the polishing equipment in the axial direction and the circumferential direction, and is formed by symmetrically arranging plane 2-RRR parallel mechanisms on two sides of a center platform, rapidly reducing the stiffness of a terminal plate, namely a connecting block, in the axial direction and the circumferential direction when the plane 2-RRR parallel mechanisms are in a singular configuration and combining a torsional spring with a pre-compression value, and can output the characteristic of negative stiffness and combine a positive stiffness pressure spring and the torsional spring to construct the two-degree-of-freedom quasi-zero stiffness vibration isolator.
The aim of the application can be achieved by the following technical scheme: a two-degree-of-freedom quasi-zero stiffness vibration isolator for polishing and grinding equipment comprises a center platform, a support column, a base, a torsion spring group and a plane 2-RRR parallel mechanism, wherein the center platform is slidably arranged on the support column through a linear bearing; two sides of the center platform are hinged with the connecting rod by pin shafts respectively to form a rotating pair;
a plurality of torsion spring sets are uniformly arranged along the circumferential direction of the center platform, and each torsion spring set comprises a torsion spring and a sliding block which are arranged on the round platform and a pulley arranged in the eccentric track; the center platform is provided with a center groove for accommodating the round platform and a different-center track positioned at the side edge of the center platform, the round platform can be sleeved on the support column in a sliding way, the round platform is arranged on the support column through a key so as to prevent the support column from rotating, and the torsion spring is arranged at the bottom of a cylindrical hole of the round platform and connected with the sliding block;
the plane 2-RRR parallel mechanism comprises a connecting block, first plate pieces respectively arranged on two end parts of the connecting block, and a bottom plate arranged opposite to the connecting block, wherein the second plate pieces and the bottom plate are sequentially hinged through a rotating shaft to form a closed-loop plane parallel mechanism, and the bottom plate is connected with a base; the connecting block is hinged with the connecting rod by a pin shaft, the central platform drives the connecting rod, the connecting rod drives the connecting block, and a torsion spring is arranged at the middle part of a rotating shaft connected with the second plate and the bottom plate;
when the connecting block and the first plate are positioned at the initial position, the connecting block and the first plate are positioned on the same plane, and the plane 2-RRR parallel mechanism is positioned at a singular position; when the axial low-frequency disturbance is received, the central platform drives the connecting rod to move upwards, the connecting block is pulled by the connecting rod to move forwards, so that the first plate and the second plate are driven to be close inwards, the torsion springs at the two ends of the bottom plate are acted by the torque from the second plate, and meanwhile, the compression springs are also acted by the pulling force from the central platform, and the two springs together generate restoring force; when receiving circumference low frequency disturbance, the center platform takes place circumference rotation along the support column, the eccentric track takes place the motion along with center platform's rotation, the pulley changes for the central point of round platform put, thereby drive the slider and carry out back-and-forth motion, and then drive the torsional spring that is connected with the slider and realize tensile or compression motion, provide torsion positive rigidity, simultaneously, the connecting rod takes place the rotation along with center platform, lead to the connecting block to take place to rotate, thereby drive first plate and second plate and take place to rotate, the torsional spring at bottom plate both ends receives the moment of torsion effect from the second plate, provide torsion negative rigidity, thereby positive and negative rigidity combined action constitutes quasi-zero rigidity vibration isolation structure.
In a preferred embodiment, a row of torsion spring mounts are provided on the inner side wall of the second plate member to provide different preload values for the torsion springs.
In a preferred embodiment, the pulley is connected to the slider by a rod, and the diameter of the pulley is equal to the width of the eccentric track.
Further, the slider includes a large diameter portion and a small diameter portion, the small diameter portion is disposed in the cylindrical hole, and the large diameter portion has a diameter larger than that of the cylindrical hole and extends out of the cylindrical hole.
Further, the circle center of the eccentric track is deviated from the circle center of the round table.
In a preferred embodiment, the two connecting rods are symmetrically distributed on two sides of the center platform and hinged through the pin shafts to form a rotating pair.
Further, the two plane 2-RRR parallel mechanisms are hinged on the connecting rod through a pin shaft and are symmetrically arranged.
Preferably, the two first plates and the connecting block are on the same plane when the planar 2-RRR parallel mechanism is in the initial position.
Preferably, the base is a U-shaped base, a base is arranged on the bottom plate of the base, and the support column is connected to the base through the base; two side walls of the U-shaped base are respectively connected with a bottom plate of the plane 2-RRR mechanism.
Preferably, the round table is arranged on the support column by means of a key so as to avoid rotational movement.
Compared with the prior art, the application has the following beneficial effects:
(1) When the plane 2-RRR parallel mechanism is in a singular configuration, the rigidity of the tail end plate in the axial direction and the circumferential direction is rapidly reduced, the torsional spring with a pre-pressing value is matched, the characteristic of negative rigidity can be output, and the torsional spring group is combined with the positive rigidity pressure spring to construct the two-degree-of-freedom quasi-zero rigidity vibration isolator. Compared with the low-frequency vibration isolator which is mainly connected in parallel by using single-degree-of-freedom vibration isolators, the vibration isolator realizes vibration isolation for low frequency or medium and low frequency in two directions along the axial direction and the circumferential direction by using only one vibration isolator.
(2) Compared with most of the quasi-zero stiffness vibration isolators in multi-dimensional directions, the two-degree-of-freedom quasi-zero stiffness vibration isolator for polishing equipment provided by the application avoids the coupling effect generated by parallel connection of a plurality of single-degree-of-freedom vibration isolators, has a lower initial vibration isolation frequency and resonance peak value, and has a better low-frequency vibration isolation effect.
(3) The two-degree-of-freedom quasi-zero stiffness vibration isolator for polishing equipment combines the singular configuration of the parallel mechanism with the vibration isolation technology, and can provide negative stiffness in the axial direction and the circumferential direction for the vibration isolator by combining the torsion spring with the pre-compression value, so that the control of multi-directional low-frequency vibration is realized by structural improvement.
Drawings
FIG. 1a is a block diagram of an overall structure of a two degree of freedom quasi-zero stiffness vibration isolator for a polishing and grinding apparatus of the present application;
FIG. 1b is a schematic view of the variation in motion of the vibration isolator when subjected to an axial disturbance in accordance with the present application;
FIG. 1c is a schematic view of the variation in motion of the vibration isolator when subjected to a circumferential disturbance in accordance with the present application;
FIG. 2 is a top view of the structure of the center platform and planar 2-RRR parallel mechanism of the application;
FIGS. 3a and 3b are a perspective view and a partial top view, respectively, of a positive stiffness cushioning mechanism of the present application;
FIGS. 4a and 4b are schematic diagrams of details of a planar 2-RRR parallel mechanism of the application;
FIG. 5 is a diagram of a force analysis of a center platform, links, and planar 2-RRR mechanism of the application;
FIG. 6 is a schematic diagram of a physical model of a three spring quasi-zero stiffness vibration isolator;
FIGS. 7a and 7b are graphs comparing force versus displacement curves for a linear spring-damper vibration isolator, a three spring quasi-zero stiffness vibration isolator, and a quasi-zero stiffness vibration isolator of the present application, respectively;
FIGS. 8a and 8b are graphs comparing stiffness-displacement curves of a linear spring-damping vibration isolator, a three spring quasi-zero stiffness vibration isolator, and a quasi-zero stiffness vibration isolator of the present application, respectively;
fig. 9a and 9b are graphs comparing force-transfer rate curves for a linear spring-damped vibration isolator, a three spring quasi-zero stiffness vibration isolator, and a quasi-zero stiffness vibration isolator of the present application, respectively.
Some of the figures are described below: the device comprises a connecting rod 1, a supporting column 2, a central platform 3, a sliding block 4, a workbench 5, a pin shaft 6, a bottom plate 7, a torsion spring 8, a first plate 9, a round table 10, a base 11, a rotating shaft 12, a second plate 13, a connecting block 14, a compression spring 15, a torsion spring 16, a linear bearing 17 and a torsion spring 18.
Detailed Description
In order that the above-recited objects, features and advantages of the present application will be more clearly understood, a more particular description of the application will be rendered by reference to the appended drawings and appended detailed description. The embodiments of the present application and the features in the embodiments may be combined with each other without collision. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application, and the described embodiments are merely some, rather than all, embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present application without making any inventive effort, are intended to fall within the scope of the present application.
In various embodiments, for convenience of description and not limitation of the present application, the technical term "coupled" as used in the specification and claims of the present application is not limited to physical or mechanical coupling, whether direct or indirect. The technical terms "upper", "lower", "left", "right", etc. are used only to indicate a relative positional relationship, which changes accordingly when the absolute position of the object to be described changes.
The application provides a two-degree-of-freedom quasi-zero stiffness vibration isolator for polishing equipment, which is shown in fig. 1a and comprises a connecting rod 1, a supporting column 2, a center platform 3, a sliding block 4, a workbench 5, a pin shaft 6, a bottom plate 7, a torsion spring 8, a first plate 9, a round table 10, a base 11, a rotating shaft 12, a second plate 13, a connecting block 14 and a pressure spring 15.
The center platform 3 is located isolator central point and puts through linear bearing 17 slidable setting support column 2 on, and the lower extreme of center platform 3 is connected with positive rigidity pressure spring 15, and the upper end of center platform 3 passes through the shaft hole cooperation and is connected with workstation 5, places the polishing equipment of polishing that needs isolation low frequency vibration on the workstation 5. The two sides of the center platform 3 are hinged with the connecting rod 1 by pin shafts 6 respectively to form a rotating pair. The support column 2 utilizes base 111 to set up on base 11, and pressure spring 15 cover is outside support column 2, and is connected with base 111 and central platform 3, plays the supporting platform and carries out the cushioning effect to the low frequency disturbance that vertical direction received. The compression spring 15 is provided with a pre-pressing value according to the quality of the polishing and grinding equipment which is actually isolated, and provides positive rigidity for the vertical direction of the vibration isolator. The pressure spring 15 is directly connected with the linear bearing 17, and plays a supporting role on the center platform 3, the workbench 5 and polishing equipment.
The two plane 2-RRR mechanisms are symmetrically distributed on two sides of the center platform 3, the tail end connecting blocks 14 of the plane 2-RRR mechanisms are hinged with the connecting rods 1 through the pin shafts 6, and when the connecting blocks 14 and the two first plates 9 are positioned on the same plane, namely the plane 2-RRR mechanisms are positioned at singular positions, and the torsional springs 8 with pre-pressing values are combined to provide negative rigidity for the vibration isolator in the axial direction and the circumferential direction.
As shown in fig. 2, which is a top view of the vibration isolator, the connecting rod 1 and the planar 2-RRR mechanism are symmetrically distributed on the left and right sides of the center platform 3. Torsion spring groups are provided in the center platform 3, and the number of torsion spring groups may be three or more. In a particularly preferred embodiment of the application, three torsion spring sets are uniformly distributed along the circumferential direction inside the central platform 3, and the pulley 41 of the slider 4 is in line contact with the eccentric track 42 to cause a change in position, thereby driving the torsion spring 16 connected to the slider 4 to perform a stretching or compressing motion.
The positive stiffness buffer device of the vibration isolator shown in fig. 3a and 3b comprises a torsion spring group and a pressure spring, and positive stiffness is provided for the vibration isolator in the circumferential direction and the axial direction respectively. The torsion spring group comprises a torsion spring 16 and a slider 4 arranged on the circular table 10, and a pulley 41 arranged in a eccentric track 42. The central platform 3 is provided with a central recess 31 accommodating the circular truncated cone 10 and the central platform 3 is provided with a decentered track 42 near the side edges, the pulley 41 being connected to the slider 4 by means of a rod 45 and abutting the decentered track 42. The circular truncated cone 10 is slidably sleeved on the support column 2, and the circular truncated cone 10 is arranged on the support column 2 through a key so as to prevent the support column 2 from rotating, so that the circular truncated cone 10 and the center platform 3 have basically fixed relative positions. The torsion spring 16 is disposed in a cylindrical hole 161 of the circular table 10 near the circumferential position and disposed in the radial direction, and the torsion spring 16 is disposed at the bottom of the cylindrical hole 161 and connected with the slider 4. The slider 4 includes a large diameter portion 43 and a small diameter portion 44, the small diameter portion 44 being provided in the cylindrical hole 161, the large diameter portion 43 having a diameter larger than that of the cylindrical hole 161 and protruding outside the cylindrical hole 161. The diameter of the pulley 41 is equal to the width of the eccentric track, so that both sides of the pulley 41 always maintain line contact with both sides of the eccentric track 42 during rotation of the eccentric track 42 with the central platform 3.
When the vibration isolator is subjected to circumferential disturbance, the round table 10 does not rotate, and the eccentric track 42 moves along with the rotation of the center platform 3, so that the pulley 41 of the sliding block 4 contacted with the eccentric track 42 slides in the eccentric track; because the round table 10 and the support column 2 are coaxially arranged, and the circle center of the eccentric track 42 is deviated from the circle center of the round table 10, namely, the circle center is not concentric, when the eccentric track 42 rotates, the line contact position of the pulley 41 and the eccentric track 42 changes, namely, the central position of the pulley 41 relative to the round table 10 changes, so that the sliding block 4 is driven to move back and forth, and the torsion spring 16 connected with the sliding block 4 is driven to realize stretching or compressing movement, and torsional positive rigidity is provided.
In the present application, the type of the eccentric track 42 is not limited to the arc type shown in fig. 3a and 3b, but may be provided in a V-type or inclined streamline type as long as the center distance of the pulley 41 with respect to the round table is changed along with the rotation of the center platform 3, thereby causing the torsion spring 16 to expand and contract.
A detailed schematic of a planar 2-RRR parallel mechanism is shown in fig. 4a and 4 b. The plane 2-RRR parallel mechanism comprises a connecting block 14, first plate members 9 respectively arranged at two ends of the connecting block 14, a bottom plate 7 opposite to the connecting block 14, and a second plate member 13 and the bottom plate 7 which are sequentially hinged through a rotating shaft 12 to form a closed-loop plane parallel mechanism. The connecting block 14 is hinged with the connecting rod 1 by a pin shaft 6, the connecting rod 1 is driven by the center platform 3, and the connecting rod 1 drives the connecting block 14, so that the plane 2-RRR mechanism moves along with the center platform. The torsion spring 8 is arranged in the middle of the rotating shaft 12 connected with the second plate 13 and the bottom plate 7, and a row of torsion spring fixing pieces 18 are arranged on the inner side wall of the second plate 13, so that different pre-pressing values can be set for the torsion spring 8 according to actual conditions. When the connecting block 14 is in a plane with the two first plates 9 on both sides, the parallel mechanism is located at a singular configuration, which has small stiffness values in both the vertical axial and circumferential directions, in combination with the torsion spring 8 with a preload value, i.e. outputs a negative stiffness at the connecting block 14.
As shown in fig. 1a, the application is provided with a U-shaped base 11, a base 111 is arranged on the bottom plate of the U-shaped base 11, and a support column 2 is connected to the base 11 through the base 111. The two side walls 112 of the U-shaped base 11 are respectively connected with the bottom plate 7 of the plane 2-RRR mechanism, and the relative spatial positions of the support columns 2 and the bottom plate 7 are kept unchanged and are fixedly arranged on the base 11.
Further, as shown in fig. 1b and 1c, the motion and the position change of the quasi-zero stiffness vibration isolator when the vibration isolator is subjected to axial low-frequency disturbance and circumferential low-frequency disturbance are respectively shown. The initial position of the vibration isolator in operation is shown in fig. 1a, the connecting block 14 and the two first plates 9 are on the same plane, at this time, the plane 2-RRR parallel mechanism is in a singular configuration, and the overall rigidity of the vibration isolator is 0.
When the vibration isolator is subjected to axial low-frequency disturbance, as shown in fig. 1b, the center platform 3 moves upwards to drive the connecting rod 1 to move upwards, and the connecting block 14 moves forwards under the horizontal pulling force of the connecting rod 1, so that the first plate 9 and the second plate 13 are driven to be close inwards, the torsion springs 8 at the two ends of the bottom plate 7 are subjected to the torque action from the second plate 13, and meanwhile, the compression springs 16 are also subjected to the pulling force action from the center platform 3, so that the two plates together generate restoring force.
When the vibration isolator is subjected to circumferential low-frequency disturbance, as shown in fig. 1c, the central platform 3 rotates circumferentially along the support column 2, and the eccentric track inside the central platform moves along with the central platform, so that the sliding block pulley drives the sliding block to move back and forth, and the internal torsion spring 16 is driven to realize stretching or compression movement, and torsional positive rigidity is provided. The connecting rod 1 rotates along with the center platform 3, so that the connecting block 14 also rotates, thereby driving the first plate 9 and the second plate 13 to rotate, and the torsion springs 8 at the two ends of the bottom plate 7 are subjected to the torque action from the second plate 13 to provide torsional negative rigidity. The positive and negative rigidity are combined to form the quasi-zero rigidity torsion mechanism, and the quasi-zero rigidity is high static and low dynamic rigidity.
When the vibration isolator is subjected to axial and circumferential disturbance at the same time, the central platform 3 is vertically displaced along the axial direction of the support column 2 and rotates along the circumferential direction of the support column 2, the connecting rod 1 moves along with the central platform 3 and drives the plane 2-RRR parallel mechanism to change in movement, and the action principle of restoring force is the same as that when the vibration isolator is subjected to disturbance independently.
The working principle of the two-degree-of-freedom quasi-zero stiffness vibration isolator is as follows:
the initial position is shown in fig. 2, the polishing and grinding device is placed on the workbench 5, the center of the polishing and grinding device is preferably collinear with the support column 2, and the vibration isolation effect is better. The pre-pressing values of the pressure spring 15 and the torsion spring 8 are set according to the quality of the polishing equipment, the pulleys of the sliding blocks 4 in the torsion spring group are in line contact with the eccentric tracks in the center platform 3, and the connecting blocks 14 and the two first plates 9 are positioned on the same plane.
When the quasi-zero stiffness vibration isolator is subjected to vertical axial and circumferential low-frequency disturbance generated by running of surrounding large instruments or devices, the pressure spring 15 provides vertical axial positive stiffness, and the torsion spring group changes through the contact position of the pulley of the sliding block 4 and the eccentric track line inside the center platform 3 to drive the internal torsion spring 16 to realize stretching or compression motion so as to provide vertical circumferential Xiang Zhuaidong positive stiffness; the plane 2-RRR mechanism utilizes the small rigidity characteristic of the singular configuration of the plane 2-RRR mechanism and the torsion spring 8 to provide negative rigidity, so that the rigidity of the center platform 3 is close to 0 in a certain range near a balance point, as shown in fig. 8a and 8b, thereby constructing a two-degree-of-freedom quasi-zero rigidity vibration isolator, reducing the natural frequency and resonance peak value of the vibration isolator, and as shown in fig. 9, being capable of isolating low-frequency disturbance of polishing equipment in two directions, namely axial and circumferential directions.
As shown in FIG. 5, the center platform 3 and the connecting rod1 and a plane 2-RRR mechanism stress analysis chart. The connecting rod 1 and the plane 2-RRR mechanism are symmetrically distributed on the two sides of the center platform 3, and the size and the hinging mode are the same, so that one side can be analyzed. Wherein the rod AF corresponds to the bottom plate 7, rod AB 1 With FE 1 Corresponding to the second plate 13, rod B 1 C 1 And rod E 1 D 1 Corresponding to the first plate 9, the rod C 1 D 1 Corresponding to the connection block 14, rod l m Corresponding to the connecting rod 1, the cuboid corresponds to the central platform 3, k τ1 、k τ2 Corresponding to the stiffness of the torsion spring 8. The initial angle of the torsion spring at the static equilibrium position is theta 0 The angles become theta respectively after the external excitation force and the moment are acted 1 、θ 2 The torque provided by the torsion spring is:
M 1 ＝k τ1 Δθ＝k τ1 (θ 0 -θ 1 )，M 2 ＝k τ2 Δθ＝k τ1 (θ 0 -θ 2 ) (1)
rod B 1 C 1 And E is connected with 1 D 1 The two-force rod is subjected to the force of the torsion spring:
and because of the connecting rod l m The projection in y direction is always perpendicular to the movable platform C 1 D 1 So torsion spring k τ1 、k τ2 By two-force lever B 1 C 1 、E 1 D 1 Acting on movable platform C 1 D 1 The force on can be divided into F x 、F y 、M C1 、M D2 Solving the following expression:
wherein F is y Provide positive rigidity for translation in the vertical direction, F x 、M C1 、M D2 Providing torsional negative stiffness in the direction of rotation. Substituting the formulas (1) and (2) into the formulas (3) and (4) can obtain the output force and moment expression of the negative stiffness mechanism as follows:
according to Hooke's law, the translational rigidity and the rotational rigidity output by the negative rigidity mechanism are F respectively y And M α Regarding the first partial derivatives of z and α, derivation of equations (5) and (6) can be obtained:
the force transmission rate is defined as the ratio of the force transmitted to the base 11 to the excitation force acting on the load moving platform. The force transmissibility can be used for measuring the quality of the vibration isolation performance of the vibration isolation system under low-frequency vibration. Meanwhile, the influence of influence factors such as exciting force amplitude, system damping and structural parameters on vibration isolation performance can be discussed by using the transmissibility. The vibration isolation load is located at the center of mass of the loading platform and the vibration isolator is in equilibrium without any external excitation. The payload mass and its moment of inertia about the center of mass through the platform are m and I, respectively. And (3) establishing a motion equation of a two-degree-of-freedom quasi-zero stiffness system by applying Newton's second motion law:
the force and moment transferred to the load platform after the external disturbance excitation passes through the two-degree-of-freedom quasi-zero stiffness vibration isolator are as follows:
the force transmissibility expression is:
fig. 6 is a schematic diagram of a physical model of a three-spring quasi-zero stiffness vibration isolator, which is used as a comparative example of the technical scheme of the present application. The three-spring quasi-zero stiffness vibration isolator of fig. 6 includes three sets of spring-damper systems, spring k v As a positive stiffness element, the base is connected with the vibration isolation platform to provide positive stiffness for the vibration isolator and play a role in supporting weights. Spring k 1 、k 2 The vibration isolation platforms are respectively positioned at two sides of the vibration isolation platform and are symmetrically arranged to form a negative stiffness element which provides negative stiffness for the vibration isolator. The vibration isolation object m is placed on the vibration isolation platform, when the spring k 1 、k 2 When the three-spring vibration isolators are positioned on two sides of the vibration isolation platform and are horizontally placed, the three-spring vibration isolators have zero stiffness characteristics, and in fig. 6, the motion changes generated when the three-spring vibration isolators are disturbed in the vertical direction.
As shown in fig. 7a and 7b and fig. 8a and 8b, a force-displacement curve comparison graph and a stiffness-displacement curve comparison graph of the linear spring-damping vibration isolator, the three-spring quasi-zero stiffness vibration isolator and the two-degree-of-freedom quasi-zero stiffness vibration isolator of the present application are obtained, respectively, and it can be seen from the graph that the quasi-zero stiffness vibration isolator is located in a certain range near the balance point, the curve is flat, and the stiffness is very small and is close to 0. When external disturbance is too large and exceeds the vibration isolation range, the rigidity of the vibration isolator is rapidly increased, and higher bearing capacity is provided, so that the vibration isolator is typical of high static state and low dynamic state, and as can be seen from comparison of figures, the vibration isolator has larger low rigidity interval, lower rigidity and better vibration isolation performance.
As shown in fig. 9a and 9b, force-transfer rate curves for a linear spring-damper vibration isolator, a three-spring quasi-zero stiffness vibration isolator, and a quasi-zero stiffness vibration isolator of the present application are obtained, respectively, from which it can be seen that the initial vibration isolation frequency of the linear vibration isolator is its own frequencyThe vibration isolator is difficult to realize an isolation effect on low-frequency vibration, and the quasi-zero stiffness vibration isolator adopts a method for reducing the self stiffness to reduce the natural frequency, so that the initial vibration isolation frequency is greatly reduced, a larger vibration isolation interval is obtained, and the low-frequency vibration control can be realized. As can be seen from comparison of the figures, the two-degree-of-freedom quasi-zero stiffness vibration isolator for polishing equipment has smaller peak value and lower initial vibration isolation frequency, can isolate disturbance with lower frequency, and has better low-frequency vibration isolation effect.
The above embodiments are only for illustrating the technical solution of the present application and not for limiting the same, and although the present application has been described in detail with reference to the above preferred embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the technical solution of the present application.

Claims (10)

1. A two degree of freedom quasi-zero stiffness vibration isolator for polishing equipment of polishing, its characterized in that: which comprises a center platform, a support column, a base, a torsion spring group and a plane 2-RRR parallel mechanism,
the center platform can be arranged on the support column in a sliding manner through the linear bearing, the pressure spring is sleeved on the support column, two ends of the pressure spring are respectively connected with the base and the center platform, the lower end of the center platform is connected with the pressure spring, the upper end of the center platform is connected with the workbench, and polishing and grinding equipment to be isolated from vibration is placed on the workbench; two sides of the center platform are hinged with the connecting rod by pin shafts respectively to form a rotating pair;
a plurality of torsion spring sets are uniformly arranged along the circumferential direction of the center platform, and each torsion spring set comprises a torsion spring and a sliding block which are arranged on the round platform and a pulley arranged in the eccentric track; the center platform is provided with a center groove for accommodating the round platform and a different-center track positioned at the side edge of the center platform, the round platform can be sleeved on the support column in a sliding way, the round platform is arranged on the support column through a key so as to prevent the support column from rotating, and the torsion spring is arranged at the bottom of a cylindrical hole of the round platform and connected with the sliding block;
the plane 2-RRR parallel mechanism comprises a connecting block, first plate pieces respectively arranged on two end parts of the connecting block, and a bottom plate arranged opposite to the connecting block, wherein the second plate pieces and the bottom plate are sequentially hinged through a rotating shaft to form a closed-loop plane parallel mechanism, and the bottom plate is connected with a base; the connecting block is hinged with the connecting rod by a pin shaft, the central platform drives the connecting rod, the connecting rod drives the connecting block, and a torsion spring is arranged at the middle part of a rotating shaft connected with the second plate and the bottom plate;
when the connecting block and the first plate are positioned at the initial position, the connecting block and the first plate are positioned on the same plane, and the plane 2-RRR parallel mechanism is positioned at a singular position; when the axial low-frequency disturbance is received, the central platform drives the connecting rod to move upwards, the connecting block is pulled by the connecting rod to move forwards, so that the first plate and the second plate are driven to be close inwards, the torsion springs at the two ends of the bottom plate are acted by the torque from the second plate, and meanwhile, the compression springs are also acted by the pulling force from the central platform, and the two springs together generate restoring force; when receiving circumference low frequency disturbance, the center platform takes place circumference rotation along the support column, the eccentric track takes place the motion along with center platform's rotation, the pulley changes for the central point of round platform put, thereby drive the slider and carry out back-and-forth motion, and then drive the torsional spring that is connected with the slider and realize tensile or compression motion, provide torsion positive rigidity, simultaneously, the connecting rod takes place the rotation along with center platform, lead to the connecting block to take place to rotate, thereby drive first plate and second plate and take place to rotate, the torsional spring at bottom plate both ends receives the moment of torsion effect from the second plate, provide torsion negative rigidity, thereby positive and negative rigidity combined action constitutes quasi-zero rigidity vibration isolation structure.
2. The two degree of freedom quasi-zero stiffness vibration isolator for a buffing and grinding apparatus according to claim 1 wherein: a row of torsional spring fixing parts are arranged on the inner side wall of the second plate, so that different pre-pressing values can be set for the torsion spring.
3. The two degree of freedom quasi-zero stiffness vibration isolator for a buffing and grinding apparatus according to claim 1 wherein: the pulley is connected to the slider by a rod, and the diameter of the pulley is equal to the width of the eccentric track.
4. A two degree of freedom quasi-zero stiffness vibration isolator for a polishing and grinding apparatus as claimed in claim 3, wherein: the slider includes major diameter portion and minor diameter portion, and minor diameter portion sets up in the cylinder hole, and the diameter of major diameter portion is greater than the diameter of cylinder hole to stretch out outside the cylinder hole.
5. The two degree of freedom quasi-zero stiffness vibration isolator for a buffing and grinding apparatus according to claim 2 wherein: the circle center of the eccentric track deviates from the circle center of the round table.
6. The two degree of freedom quasi-zero stiffness vibration isolator for a buffing and grinding apparatus according to claim 1 wherein: the two connecting rods are symmetrically distributed on two sides of the center platform and hinged through the pin shafts to form a rotating pair.
7. The two degree of freedom quasi-zero stiffness vibration isolator for a buffing and grinding apparatus according to claim 6 wherein: the two plane 2-RRR parallel mechanisms are hinged on the connecting rod through a pin shaft and are symmetrically arranged.
8. The two degree of freedom quasi-zero stiffness vibration isolator for a buffing and grinding apparatus according to claim 7 wherein: when the plane 2-RRR parallel mechanism is at the initial position, the two first plates and the connecting block are positioned on the same plane.
9. The two degree of freedom quasi-zero stiffness vibration isolator for a buffing and grinding apparatus according to claim 1 wherein: the base is a U-shaped base, a base is arranged on the bottom plate of the base, and the support column is connected to the base through the base; two side walls of the U-shaped base are respectively connected with a bottom plate of the plane 2-RRR mechanism.
10. The two degree of freedom quasi-zero stiffness vibration isolator for a buffing and grinding apparatus according to claim 1 wherein: the round platform is arranged on the support column through a key so as to avoid rotary motion.
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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106870615A (en) * 2017-04-21 2017-06-20 吉林大学 A kind of dish type non-linear low frequency vibration isolator based on positive and negative Stiffness principle
CN209228936U (en) * 2018-12-27 2019-08-09 哈尔滨工业大学 A kind of quasi-zero stiffness vibration isolators based on translot spring
CN110848313A (en) * 2019-10-09 2020-02-28 东北大学 Semi-circular slide rail type quasi-zero stiffness vibration isolator
CN111927912A (en) * 2020-07-15 2020-11-13 江苏大学 Quasi-zero rigidity vertical vibration isolator capable of realizing balance position adjustment
CN112268095A (en) * 2020-11-26 2021-01-26 北京市劳动保护科学研究所 Quasi-zero rigidity vibration isolation device with automatically adjusted balance position
CN112701957A (en) * 2020-12-24 2021-04-23 南京航空航天大学 Variable-rigidity tuned piezoelectric energy harvester
CN114934974A (en) * 2022-05-13 2022-08-23 东莞理工学院 Large-amplitude horizontal two-degree-of-freedom vibration isolator

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106870615A (en) * 2017-04-21 2017-06-20 吉林大学 A kind of dish type non-linear low frequency vibration isolator based on positive and negative Stiffness principle
CN209228936U (en) * 2018-12-27 2019-08-09 哈尔滨工业大学 A kind of quasi-zero stiffness vibration isolators based on translot spring
CN110848313A (en) * 2019-10-09 2020-02-28 东北大学 Semi-circular slide rail type quasi-zero stiffness vibration isolator
CN111927912A (en) * 2020-07-15 2020-11-13 江苏大学 Quasi-zero rigidity vertical vibration isolator capable of realizing balance position adjustment
CN112268095A (en) * 2020-11-26 2021-01-26 北京市劳动保护科学研究所 Quasi-zero rigidity vibration isolation device with automatically adjusted balance position
CN112701957A (en) * 2020-12-24 2021-04-23 南京航空航天大学 Variable-rigidity tuned piezoelectric energy harvester
CN114934974A (en) * 2022-05-13 2022-08-23 东莞理工学院 Large-amplitude horizontal two-degree-of-freedom vibration isolator

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