CN102506110B - Permanent magnet low frequency single-degree-of-freedom vibration isolation mechanism based on negative stiffness theory - Google Patents

Abstract

A ring-shaped permanent magnet low-frequency vibration isolation mechanism based on the principle of negative stiffness, including an upper rubber sheet, an inner ring-shaped permanent magnet fixed mandrel, an upper pressure ring of the upper rubber sheet, an outer pressure ring of the upper rubber sheet, an outer ring-shaped permanent magnet, a lower rubber sheet, The inner pressure sheet of the lower rubber sheet, the outer pressure ring of the lower rubber sheet, the outer ring permanent magnet fixing sleeve and the inner ring permanent magnet. Among them, the inner ring permanent magnet is axially magnetized, and the outer ring permanent magnet is radially magnetized. The inner and outer ring permanent magnets form a positive stiffness system, and the upper and lower rubber sheets form a negative stiffness system. The positive and negative stiffness systems can be used in parallel to form a low-frequency vibration isolation mechanism. Three or four single-degree-of-freedom vibration isolation mechanisms can be used in parallel to achieve three-degree-of-freedom low-frequency vibration isolation; when the magnetic field force of the vibration isolation mechanism is maximum, its stiffness is close to zero. The invention does not need an external air source and has the prospect of being used in vacuum; it has the characteristics of simple structure, low cost and easy processing; it can be used in the fields of optics, acoustics, biology, semiconductor manufacturing, precision measurement and the like.

Description

A permanent magnet low-frequency single-degree-of-freedom vibration isolation mechanism based on the principle of negative stiffness

technical field

The invention relates to a low-frequency vibration isolation mechanism, in particular to a ring-shaped permanent magnet low-frequency vibration isolation mechanism based on the principle of negative stiffness, which is mainly used for ultra-low frequency of small and medium-sized instruments and equipment in the fields of optics, acoustics, semiconductor manufacturing, precision measurement and ultra-precision vibration isolation.

Background technique

倍，起减振作用，可较好地隔离中、高频振动，但隔离低频振动尤其是超低频振动的能力较差。为了提高系统隔离低频振动的能力，通常有两种方法：一是减小隔振系统的刚度；二是增加承载质量。对于线性隔振器在相同负载下变形较大及降低隔振系统的稳定性，但承载能力也受到限制。因此，传统被动隔振系统已无法满足超精密加工及测量等领域对隔离超低频宽频带振动的需要，需要开展新型非线性隔振器的研究。若采用主动控制，可降低固有频率，提高隔振性能，但成本太高。自Platus提出了负刚度原理后，近年来，国内外应用了负刚度原理研究出各种隔振器，虽然隔振性能有所提高，但其承载能力较小，使用时还需要根据负载进行刚度调谐。In the field of ultra-precision, precision and ultra-precision machining have increasingly stringent environmental requirements, because vibration interference inside and outside mechanical equipment is one of the important factors that reduce machining accuracy and surface quality. The quality of ultra-precision machining is not only related to the amplitude of vibration interference, but also related to the frequency of vibration interference. The vibration frequency that has an adverse effect on ultra-precision machining is a slight vibration in the range of 0.5-70Hz. The vibration control method is commonly used to eliminate Vibration, vibration isolation and vibration absorption, the most widely used in the ultra-precision field is vibration isolation. At present, the vibration isolation mechanism mainly has the following forms: rubber, three-wire pendulum, inverted pendulum, X pendulum and swing ball. Among them, the rubber structure is simple, and it is difficult to achieve a lower natural frequency. The inverted pendulum and the X pendulum can only isolate vibration in one horizontal direction. In the vertical direction, the air spring has the best vibration isolation effect at present, which requires an external air source and cannot be used in a vacuum. It can be seen from the vibration reduction theory that the traditional passive vibration isolation system has a higher frequency of external interference than the natural frequency of the vibration isolation system.

times, it plays the role of vibration damping, which can better isolate medium and high frequency vibrations, but the ability to isolate low frequency vibrations, especially ultra-low frequency vibrations, is poor. In order to improve the ability of the system to isolate low-frequency vibrations, there are usually two methods: one is to reduce the stiffness of the vibration isolation system; the other is to increase the bearing mass. For linear vibration isolators, the deformation is large under the same load and the stability of the vibration isolation system is reduced, but the bearing capacity is also limited. Therefore, the traditional passive vibration isolation system can no longer meet the needs of ultra-precision machining and measurement for isolating ultra-low frequency broadband vibration, and it is necessary to carry out research on new nonlinear vibration isolators. If active control is used, the natural frequency can be reduced and the vibration isolation performance can be improved, but the cost is too high. Since Platus proposed the principle of negative stiffness, in recent years, various vibration isolators have been developed by applying the principle of negative stiffness at home and abroad. Although the vibration isolation performance has been improved, their bearing capacity is small, and the stiffness needs to be adjusted according to the load when used. tuning.

Contents of the invention

The purpose of the present invention is to propose a low-frequency vibration isolation mechanism based on the principle of negative stiffness, which has both high bearing capacity and low natural frequency, and can realize ultra-low frequency vibration isolation with a single degree of freedom in the vertical direction. It can also be used in combination to realize low-frequency vibration isolation with three degrees of freedom, and the vibration isolation performance is good.

The purpose of the present invention is achieved through the following technical solutions:

A ring-shaped permanent magnet low-frequency single-degree-of-freedom vibration isolation mechanism based on the principle of negative stiffness, characterized in that: the ultra-low frequency vibration isolation mechanism includes an inner ring permanent magnet, an outer ring permanent magnet, an upper rubber sheet, a lower rubber sheet, an upper Rubber sheet inner pressure ring, upper rubber sheet outer pressure ring, lower rubber sheet inner pressure ring, lower rubber sheet outer pressure ring, inner ring permanent magnet fixing mandrel and outer ring permanent magnet fixing sleeve; the inner ring permanent magnet is axially magnetized, The outer ring permanent magnet is radially magnetized, and the inner ring and the outer ring permanent magnet are concentrically arranged; the inner ring permanent magnet is fixed on its mandrel; the outer ring permanent magnet is bonded to its fixing sleeve; The outer edge of the upper rubber sheet is fixed with the top surface of the outer annular permanent magnet through the upper rubber sheet outer pressure ring, and the middle part of the upper rubber sheet is fixed with the top surface of the inner annular permanent magnet through the upper rubber sheet upper pressure ring; The outer edge of the rubber sheet is fixed by the bottom surface of the lower rubber sheet outer pressure ring and the outer annular permanent magnet, and the middle part of the lower rubber sheet is fixed by the bottom surface of the lower rubber sheet inner pressure sheet and the inner annular permanent magnet fixed mandrel.

The fixed mandrel of the inner ring permanent magnet is provided with an upper shoulder and a lower shoulder, the upper shoulder is flush with the top surface of the inner ring permanent magnet, and the lower shoulder is flush with the bottom surface of the inner ring permanent magnet.

Both the upper rubber sheet and the lower rubber sheet can adopt industrial rubber or natural rubber.

The present invention provides a ring-shaped permanent magnet low-frequency three-degree-of-freedom vibration isolation mechanism based on the principle of negative stiffness, which is characterized in that: the mechanism is composed of three or four low-frequency single-degree-of-freedom vibration isolation mechanisms. The three low-frequency single-degree-of-freedom vibration isolation mechanisms are evenly distributed on the same circle; the four low-frequency single-degree-of-freedom vibration-isolation mechanisms form a square structure; the three degrees of freedom rotate around the x-axis and around the y-axis and Three degrees of freedom for movement in the z direction.

Compared with the prior art, the present invention has the following advantages and outstanding effects: ① The low-frequency vibration isolation mechanism proposed by the present invention does not require external energy input, so it has a good application prospect in vacuum. ②When the magnetic field force between the permanent magnets is the largest, its stiffness is close to zero, so low-frequency vibration isolation can be realized. Low natural frequency and good vibration isolation performance. ③ The low-frequency vibration isolation mechanism of the present invention is composed of inner and outer annular permanent magnets, rubber and its accessories, and has a simple structure, relatively low cost, and is easy to process and manufacture.

Description of drawings

Fig. 1 is a main sectional view of an annular permanent magnet low-frequency single-degree-of-freedom vibration isolation mechanism based on the principle of negative stiffness provided by the present invention.

FIG. 2 is a top view of FIG. 1 .

FIG. 3 is a schematic diagram of the ring-shaped permanent magnet low-frequency single-degree-of-freedom vibration isolation mechanism based on the principle of negative stiffness provided by the present invention.

Fig. 4 is an appearance diagram of the annular permanent magnet low-frequency three-degree-of-freedom vibration isolation mechanism based on the principle of negative stiffness provided by the present invention (four low-frequency single-degree-of-freedom vibration isolation mechanisms form a square distribution).

Fig. 5 is an appearance diagram of the ring-shaped permanent magnet low-frequency three-degree-of-freedom vibration isolation mechanism based on the principle of negative stiffness provided by the present invention (three low-frequency single-degree-of-freedom vibration isolation mechanisms are uniformly distributed in a circle).

In the figure: 1-upper rubber sheet; 2-inner annular permanent magnet fixed mandrel; 3-upper pressure ring of upper rubber sheet; 4-outer pressure ring of upper rubber sheet; 5-outer annular permanent magnet; 6-lower rubber sheet; 7 - the inner pressure piece of the lower rubber sheet; 8 - the outer pressure ring of the lower rubber sheet; 9 - the outer ring permanent magnet fixing sleeve; 10 - the inner ring permanent magnet; in the figure: 11 - the lower support plate; 12 - the upper support plate; 13 - Load; 14-low frequency single degree of freedom vibration isolation mechanism.

Detailed ways

Fig. 1, such as 2 are the structural representations of the ring-shaped permanent magnet low-frequency single-degree-of-freedom vibration isolation mechanism based on the principle of negative stiffness provided by the present invention. The ring-shaped permanent magnet low-frequency single-degree-of-freedom vibration isolation mechanism includes an inner ring permanent magnet 10, an outer ring permanent Magnet 5, upper rubber sheet 1, lower rubber sheet 6, inner annular permanent magnet fixed mandrel 2, upper rubber sheet upper pressure ring 3, upper rubber sheet outer pressure ring 4, lower rubber sheet inner pressure sheet 7, lower rubber sheet outer pressure Ring 8 and outer annular permanent magnet fixing sleeve 9; inner annular permanent magnet 10 is axially magnetized, outer annular permanent magnet 5 is radially magnetized, and inner annular permanent magnet and outer annular permanent magnet are arranged concentrically; The inner ring permanent magnet is fixed on the mandrel 2; the outer ring permanent magnet 5 is bonded on the outer ring permanent magnet fixing sleeve 9; the outer edge of the upper rubber sheet 1 passes through the outer pressure ring 4 of the upper rubber sheet and the outer ring permanent magnet The top surface of 5 is fixed, and the middle part of the upper rubber sheet 1 is fixed by the top surface of the upper rubber sheet upper pressure ring 3 and the permanent magnet of the inner ring; the outer edge of the lower rubber sheet 6 is connected with the outer ring by the lower rubber sheet pressure ring 8. The bottom surface of the permanent magnet is fixed, and the middle part of the lower rubber sheet 6 is fixed by the bottom surface of the inner annular permanent magnet fixed mandrel 2 by the lower rubber inner pressure sheet 7 . The upper rubber sheet and the lower rubber sheet adopt industrial rubber or natural rubber.

The fixed mandrel 2 of the inner ring permanent magnet is provided with an upper shoulder and a lower shoulder, the upper shoulder is flush with the top surface of the inner ring permanent magnet, and the lower shoulder is flush with the bottom surface of the inner ring permanent magnet; the upper rubber sheet The upper pressure ring 3 and the bolt are fixed together with the inner ring permanent magnet 10 by the upper rubber sheet; the lower rubber sheet is fixed together with the inner ring permanent magnet fixing mandrel 2 by the lower rubber sheet inner pressure sheet 7 and bolts.

Fig. 3 is a schematic diagram of vibration isolation in the vertical direction of the structure of the annular permanent magnet low-frequency single-degree-of-freedom vibration isolation mechanism based on the principle of negative stiffness provided by the present invention. The inner and outer annular permanent magnets in the annular permanent magnet low-frequency single-degree-of-freedom vibration isolation mechanism based on the principle of negative stiffness are equivalent to a magnetic spring, whose stiffness is K _v , wherein the rubber also produces stiffness under the action of repulsion, and its is K _L , the component in the vertical direction is K _L sinθ, but its direction is opposite, the magnetic spring produces positive stiffness, and the rubber produces negative stiffness. The stiffness pair of the low-frequency single-degree-of-freedom vibration isolation mechanism in the vertical direction can be expressed as:

Among them, K is the total stiffness of the low-frequency single-degree-of-freedom vibration isolation mechanism in the vertical direction, K _{magnetic spring} is the stiffness of the inner and outer ring permanent magnets in the vertical direction, K _rubber is the stiffness of the rubber in the vertical direction, and θ rubber is the clamp between the horizontal line angle, x is the displacement in the vertical direction, and γ is the cosine value of the angle θ between the rubber and the horizontal line (0<γ<1).

可得，固有频率f趋近于零，故可实现低频隔振，M为负载的质量。It can be seen from the above formula that the stiffness of the rubber can partially offset the stiffness produced by the permanent magnet, so that the stiffness of the vibration isolation mechanism can be reduced, or even reach zero. According to

It can be obtained that the natural frequency f approaches zero, so low-frequency vibration isolation can be achieved, and M is the mass of the load.

Figure 4 is the appearance of four ring-shaped permanent magnet low-frequency single-degree-of-freedom vibration isolation mechanisms based on the principle of negative stiffness used in parallel to achieve a three-degree-of-freedom vibration isolation mechanism, that is, four low-frequency single-degree-of-freedom vibration isolation mechanisms form a square structure, each The low-frequency single-degree-of-freedom vibration isolation mechanism can be equivalent to a spring-damping system; the three-degree-of-freedom is rotation around the x-axis and y-axis and movement along the z-axis.

The vibration isolation principle of rotating around the x direction is that when external disturbance acts on the load counterclockwise around the x axis, the relative axial displacement of the inner and outer rings of the two vibration isolation units A and B decreases, and the magnetic force increases; at the same time , The relative axial displacement of the inner and outer rings in the two vibration isolation units C and D increases, and the magnetic force decreases, and the load will return to the original equilibrium position under the action of the magnetic force to achieve vibration isolation. Conversely, when the external disturbance acts on the load clockwise around the x-axis, vibration isolation can be achieved in the same way.

The principle of the vibration isolation around the y-axis direction is the same as the vibration isolation around the x-axis direction, and will not be repeated here.

The principle of vibration isolation along the Z-axis direction is that when external disturbances along the negative z-direction act on the load, the axial displacement between the inner and outer annular permanent magnets decreases, the magnetic field force increases, and the pulling force of the rubber decreases. , the load will return to the equilibrium position under the action of magnetic force and rubber to achieve vibration isolation; on the contrary, if there is an upward external disturbance acting on the load, the axial displacement of the permanent magnets of the inner and outer rings will increase, and the axial magnetic force will decrease. The rubber is stretched and the stiffness increases, and the load will return to the equilibrium position under the action of the magnetic force and the rubber to achieve vibration isolation.

Figure 5 is the appearance diagram of the annular permanent magnet low-frequency three-degree-of-freedom vibration isolation mechanism based on the principle of negative stiffness, that is, the three low-frequency single-degree-of-freedom vibration isolation mechanisms are evenly distributed on the same circle, and each low-frequency single-degree-of-freedom vibration isolation unit is It can be equivalent to a spring damping system; the three ring-shaped low-frequency single-degree-of-freedom vibration isolation mechanisms can be used in parallel to realize movement along the z direction, rotation vibration isolation in the x direction and y direction, and its principle is the same as that shown in Figure 4 The vibration isolation effect is the same, but the bearing capacity is different.

Claims (4)

1. annular permanent magnet low frequency single-degree-of-freedom vibration isolating mechanism based on negative rigidity principle is characterized in that: this vibration isolating mechanism comprises compressing tablet (7), lower sheet rubber outer press ring (8), outer ring permanent magnet fixed cover (9) and interior annular permanent magnet (10) in sheet rubber (1), interior annular permanent magnet stationary spindle (2), upper sheet rubber upper press ring (3), upper sheet rubber outer press ring (4), outer ring permanent magnet (5), lower sheet rubber (6), the lower sheet rubber; Described interior annular permanent magnet (10) axial magnetized, outer ring permanent magnet (5) diametrical magnetization, interior annular permanent magnet and outer ring permanent magnet arranged concentric; Described interior annular permanent magnet is fixed on the interior annular permanent magnet stationary spindle (2); Described outer ring permanent magnet (5) is bonded on the outer ring permanent magnet fixed cover (9); The outer rim of described upper sheet rubber (1) is fixed by upper sheet rubber outer press ring (4) and the end face of outer ring permanent magnet (5), and the intermediate portion of upper sheet rubber (1) is fixed by upper sheet rubber upper press ring (3) and the end face of interior annular permanent magnet (10); The outer rim of described lower sheet rubber (6) is fixed by lower sheet rubber outer press ring (8) and the bottom surface of outer ring permanent magnet (5), and the intermediate portion of lower sheet rubber (6) is fixed by compressing tablet (7) in the lower sheet rubber and the bottom surface of interior annular permanent magnet stationary spindle (2).

2. according to a kind of annular permanent magnet low frequency single-degree-of-freedom vibration isolating mechanism based on negative rigidity principle claimed in claim 1, it is characterized in that: described interior annular permanent magnet stationary spindle is provided with the shaft shoulder and the lower shaft shoulder, the upper shaft shoulder flushes with the end face of interior annular permanent magnet, and the lower shaft shoulder flushes with the bottom surface of interior annular permanent magnet.

3. according to a kind of annular permanent magnet low frequency single-degree-of-freedom vibration isolating mechanism based on negative rigidity principle claimed in claim 1, it is characterized in that: described upper sheet rubber and lower sheet rubber adopt industrial rubber or natural rubber.

4. annular permanent magnet low frequency Three Degree Of Freedom vibration isolating mechanism based on negative rigidity principle, it is characterized in that: this mechanism is comprised of three or four low frequency single-degree-of-freedom vibration isolating mechanisms as claimed in claim 1, described three low frequency single-degree-of-freedom vibration isolating mechanisms are evenly distributed on the same circumference, or described four low frequency single-degree-of-freedom vibration isolating mechanisms are formed square structure; Described Three Degree Of Freedom refers to around x axle direction and the Three Degree Of Freedom that rotates and move along the z axle direction around the y axle direction.

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