KR100904703B1 - Torsion bar assembly for control of rotational vibration and vibration control table using that - Google Patents

Abstract

A torsion bar assembly for controlling rotational vibration and a vibration absorber using the same are provided to increase a natural frequency of a rotational vibration mode by using two torsion bars. A torsion bar assembly for controlling rotational vibration comprises a rod which is made of elastic material; a torsion bar(31) which includes a torsion bar bracket(311) which is combined in the middle of the rod and permitted to rotate; two torsion arms(32) which are orthogonally combined in both ends of the torsion bar; and a support rod(33) in which a fixing bracket(332) whereof ball-joints(331) are adhered in both ends is prepared. To torsion arms are combined to each other in the coupling portion with the torsion bar and not allowed to rotate around each other.

Description

Torsion Bar Assembly for Control of Rotational Vibration and Vibration Control Table Using That}

The present invention relates to vibration control, and more particularly, to a device for controlling rotational vibrations such as pitching and rolling and a vibration damping table using the same.

Semiconductor manufacturing equipment and inspection equipment operate in a very quiet vibration environment, which occurs when people walk to the surrounding areas as well as vibrations generated from vibration-inducing machines such as motors, fans, and pumps installed around them. Vibration of the building can adversely affect the operation of these precision equipment. Therefore, such precision equipment is generally installed by using a vibration isolator that separates from the surrounding vibration environment.

Such precision equipment is generally dustproof using a vibration damper, which is composed of a dustproof device capable of blocking vibration and a heavy weight inertial base having great inertia. As the vibration isolator, a vibration mount using an elastic body such as a rubber pad, a rubber mount, a metal spring mount, or an air mount is used. The vibration damper prevents the excitation force generated during the operation of the machine from being transmitted to the structure or vice versa from the transmission of the surrounding vibrations to the protected machine.

As the elastic body used for the vibration mount, all kinds of elastic materials can be used as the dustproof material. Among the elastic materials, the air mount can constitute a dustproof system with a very low natural frequency, so that the dustproofing efficiency can be increased, and the fine vibration and It has a large damping rate against impact vibration and a large amount of vibration amplification in the resonance region, so it is widely used for vibration damping for precision equipment. In particular, high-precision equipment such as semiconductor manufacturing equipment uses air mount for high vibration blocking.

The vibration damper for the vibration of precision equipment is composed of one vibration system with mass, spring and damper. The vibration damper is plate-shaped with the width enough to install the equipment on it and has 4 or more support points. It is not a single degree of freedom vibration system that vibrates in one direction of movement only, but linear motion in three axes (three directions, the x-axis in the front and rear directions, the y-axis in the horizontal direction and the z-axis in the vertical direction), It is a six degree of freedom system vibration system that performs rotational movement (pitching, rolling, and yawing) about the three axes.

In general, a factory building in which precision equipment is operated is designed to have a very large rigidity, but the horizontal vibration is not a problem, and the vibration damping zone is designed to control only the vertical vibration mode, which is mainly vertical. In the design of the vibration control system for controlling the vertical vibration as described above, assuming that the vibration system is a single degree of freedom vibration system, the spring constant of the system is obtained by the sum of the vertical spring constants of the vibration mounts, which are used in parallel, and the inertia base The mass is obtained by summing the mass of the and the equipment, then the natural frequency of the system is obtained from the spring constant and the mass, and the frequency ratio is obtained by dividing the excitation frequency by the natural frequency to obtain the vibration transfer rate and the vibration damping efficiency.

In the vibration design of the conventional precision equipment as described above, the vibration system is assumed to be a single degree of freedom vibration system, but the actual vibration system is a six degree of freedom vibration system as described above, among which the rolling vibration which is the rotational vibration mode about the x axis and Pitching vibration, a rotational vibration mode about the y-axis, also applies vertical force to the floor of the building. Therefore, vertical excitation due to such rotational vibration is transmitted to the floor of the building, or vibration of the building is applied to the precision equipment for pitching and rolling vibration. Often cause problems.

In order to control the vertical vibration of the precision equipment to a sufficient degree, when the natural frequency of the vertical vibration mode of the vibration damper where the equipment is installed is designed to 2 to 3 Hz, the natural frequency of the rotational vibration mode of pitching and rolling may be 10 to At 20Hz, it can be considerably higher than the natural frequency of the vertical vibration mode, and this rotational vibration coincides with the natural frequency of the building, causing resonance. In such a case, it is difficult to avoid resonance by lowering the natural frequency of the rotational vibration mode, and it is realistic to avoid the resonance by making the natural frequency of the rotational vibration mode considerably higher than the natural frequency of the building (for example, 30 to 40 Hz).

For the above reasons, in the design of the vibration control system of precision equipment, a method for increasing the natural frequency of the rotational vibration mode while maintaining the natural frequency of the vertical vibration mode, which is mainly a problem, should be taken. However, up to now, no vibration damper with means having such vibration characteristics has been developed.

As described above, the vibration damper for controlling the vibration of the conventional precision equipment has used the air mount in the vertical direction to control the vibration in the vertical vibration mode, but thus the vibration of the precision equipment using the air mount is controlled. Vibration damping for the purpose is required means for controlling the vibration of the rotational vibration mode of pitching and rolling.

In order to solve the above technical problem, the present invention does not affect the natural frequency of the vertical vibration mode determined by the mass of the inertial base (including the equipment installed on the inertial base) and the spring constant of the plurality of air mounts, The natural frequency of the rotational vibration mode of rolling and rolling was considerably increased.

The torsion bar's torsional elasticity was used as a specific means to increase the natural frequency of the rotational vibration mode.

In case of using the vibration damping control device of the present invention, in order to effectively block the vertical vibration, the vertical spring constant and the natural frequency of the vibration system are kept very low, while the natural frequency of the rotational vibration mode of pitching and rolling is arbitrarily high. Thus, it is possible to effectively control the vibration of all directions, in particular the rotational vibration of the pitching and rolling, which is a problem in the vibration control of precision equipment.

As shown in FIG. 1, the vibration damping control device of the present invention has a plate shape, which allows equipment to be installed thereon, and has elasticity with an inertia base (1, Inertia Base) having a large motion inertia with a heavy weight to block vibration. In the conventional vibration isolator composed of a plurality of vibration mounts (2) to function, the torsion bar assembly 3 for controlling the rotation vibration in the front and rear direction (hereinafter referred to as x direction) and the left and right directions (hereinafter, It is provided with one or more in the y direction.).

The inertial base 1 is also called an additional base, and has the same function and configuration as the inertial base of a conventional dustproof system. The upper surface is provided with the equipment for vibration control being fixed, and the lower surface or side has a bracket for attaching the dustproof mount. It is. This inertial base increases the mass of the vibration system to lower the natural frequency of the system, and lowers the sensitivity of the system (this is usually referred to as "mobility", which is mobility = vibration speed amplitude / vibration amplitude). Reduce vibration response to excitation force.

The dustproof mount 2 has the same structure and function as a conventional dustproof mount used for vibration control. A typical dustproof mount is provided with a bracket above and below an elastic body such as rubber, metal springs, air springs, the bottom of which is fixed to the floor where the equipment is to be installed, and the top of which is fixed to the inertial base 1 so that the equipment subject to vibration control is By supporting the installed inertial base 1, the inertial base can be supported by an elastic body.

The present invention is used for the vibration of precision equipment that requires a very high degree of vibration blocking, the vibration mount (2) used in the present invention mainly uses a spring mount or air spring using a metal coil spring with a large static deformation Air mount used.

The torsion bar assembly 3 is coupled to both ends of the torsion bar 31 and the torsion bar 31 providing torsional elasticity, as shown in FIG. Two torsion arms 32 forming a c-shape together with the torsion bar are provided with fixing brackets having ball joints at both ends thereof, one end of which is attached to the torsion arm 32 and the other end of which is fixed to the floor. It is configured to include).

Torsion bar 31 is a rod having a predetermined length made of a material having a torsional elasticity, and uses a metal rod such as steel, brass, stainless steel, and the like having a circular cross section. When a rod of constant length is subjected to torque, the torsion angle θ in the elastic deformation region is calculated as θ = TL / GJ. Where T is the torsional torque, L is the length of the rod, G is the lateral modulus of material, and J is the moment of inertia of the cross section. If the circular cross-section rod diameter d, second moment of area (J) is πd ^4/32.

When the torsion spring constant K _θ of the rod is obtained by the above equation, K _θ = T / θ = GJ / L. As can be seen from this equation, the torsion bar with the desired torsion spring constant can be designed by adjusting the rod length (L) and the rod diameter (d) in the torsion bar of a specific material (eg steel).

In the middle of the torsion bar 31, two or more torsion bar brackets 311 having a bracket for fixing the torsion bar to the lower surface of the inertia base 1 are combined. It is recommended to install a bearing in the shaft hole of the torsion bar bracket so that it can rotate.

Torsion arm 32 is coupled to the torsion bar at right angles to both ends of the torsion bar 31 in the same direction and coupled to form a c-shape with the torsion bar, the torsion arm 32 and the torsion bar 31. In order to prevent rotation between each other, install the key, or process the end of the torsion bar into 4, 6, etc., and insert the end of the torsion bar into the torsion arm. Rigid bonds are made, for example by bonding. Since the torsion arm is mainly subjected to the bending moment, the cross-sectional shape is preferably square or I-shaped.

One end of the support rod 33 is fixed to the end of the torsion arm 32, which is not coupled to the torsion bar 31, and the other end is fixed to the bottom. The support rod has ball joints 331 attached to both ends thereof so that both ends can be rotated in all directions. The support rod is divided into two parts, the upper part and the lower part, to facilitate the length adjustment. It is good to make. Ball joints on both ends of the support rod are provided with fixing brackets 332, respectively, so that they can be fixed to the bottom and torsion arm 32, respectively.

If the vibration in either direction of the horizontal vibration is not a problem at all, for example, if the vibration damper is not likely to occur in the forward and backward direction or if the problem does not occur, it is one direction instead of the ball joint 331. Only by rotating the pin can be made freely.

The function of the torsion bar assembly 3 as described above is as follows.

If the vibration damper is in rotational vibration mode, for example, pitching vibration, one end of the vibration damper goes up and the other end goes down. At this time, the torsion bar 31 of the torsion bar assembly 3 attached to the vibration damping table in the x direction is also shown in (a) of FIG. 3, with one end going up and the other end going down. (The torsion bar and the torsion arm after deformation are indicated by dotted lines.) Since the length of the support rod 33 does not change and one end is fixed to the bottom, the upper end of the torsion arm 32 which is ball jointed with the support rod 33. Silver does not move up and down, the end of the torsion bar of the torsion arm (32) is rigidly coupled with the torsion bar (31), one end goes up and the other end goes down. At this time, the torsion arm 32 is rotated at the coupling portion with the support rod and the restraining force (F) acts vertically upward or vertically downward. Torque bar 31, which is a value obtained by multiplying the magnitude of the restraining force by the length L of the torsion arm, is applied to the torsion bar 31, and torsional deformation θ occurs in the torsion bar.

Of the number of the first twist deformation (θ) to the torsion bar 31 provided in the x-axis direction by a pitching motion of the vibration removal table as described above occurs, and multiplied by the torsional spring constant (K _θ) of the torsion bar to twist deformation An elastic restoring force T is generated to control the vibration of the vibration damper. The torsion bar 31 serves as a torsion spring in the pitching vibration of the rotational vibration mode.

To control the rolling vibration in the vibration vibration mode of the vibration damper, when the torsion bar assembly 3 is installed in the y direction, it is controlled by the same mechanism as the pitching vibration.

If the vibration damper vibrates in the up and down direction (z direction), as shown in FIG. 3 (b), both ends of the torsion bar rotate in the same direction at the ball joint connection portion with the support rod, and thus the torsion bar is damped. Exercise up and down with no restraint. In this case, all loads of the vibration isolator are restrained by the vibration mounts as in the normal vibration damper, and the vertical vibration is controlled by the vibration mounts.

If the vibration damper vibrates horizontally in the front-back (x-direction) or left-right (y-direction) direction, as shown in Fig. 3 (c), the ball joint at the coupling portion between both ends of the torsion bar and the bottom of the support rod is shown. Since the rotation occurs in the same direction at the joint, the torsion bar moves forward, backward, left and right without being bound by the vibration damper. In this case, all the loads of the vibration isolator are bound by the horizontal resistance of the vibration mount or the vibration mount mounted separately in the horizontal direction as in the case of the general vibration damping band, and the horizontal vibration is controlled by these vibration mounts.

With the above mechanism, the torsion bar assembly provided in addition to the conventional vibration damping band restrains the vibration of the rotation mode of pitching or rolling without restraining the linear and vertical vibrations of the vibration damping band in the horizontal and vertical directions.

In order to control the vibration mode of the vibration damper, one of the torsion bar assemblies 3 configured as described above may be installed in the center of the lower surface of the vibration damper, or the vibration damper is very large and heavy so that two or more torques may be applied during rotation vibration. It is also possible to install a plurality of parallel to each other.

Yawing vibration, which is a rotational vibration about the z-axis among the vibrations of the rotation mode, can be controlled by arranging the torsion bar assembly 3 vertically. However, since the yaw vibration is rarely a problem in the vibration damping table, the present invention does not consider this.

The torsion bar assembly of the present invention and the vibration damper using the same can be used for vibration control of ultra precision processing equipment or inspection equipment such as semiconductor manufacturing equipment and electron microscope.

1 is a vibration damper according to the present invention.

2 is a torsion bar assembly of the present invention.

3 is a diagram in which the torsion bar assembly deforms in each vibration mode.

※ Main component number

1: inertial base, 2: dustproof mount, 3: torsion bar assembly,

31: torsion bar, 32: torsion arm, 33: support rod

Claims (2)

A torsion bar bracket 311 having a rod having a predetermined length made of an elastic material and providing a torsional elasticity, and a bracket that is rotatably coupled to the rod in the middle of the rod and attachable to another object, Torsion bar 31; Both ends of the torsion bar 31 are coupled to the torsion bar 31 at right angles, respectively, the two are coupled in the same direction to form a c-letter together with the torsion bar 31, and a coupling portion with the torsion bar 31. Two torsion arms 32, which are rigidly coupled to each other so as not to rotate in each other; In addition, a fixed bracket 332 having a ball joint 331 rotatable in an arbitrary direction is provided at both ends, and one end of the fixed bracket 332 is attached to the torsion arm 32 and fixed at the other end. Bracket 332 is a support rod 33, fixed to the floor; A torsion bar assembly (3), comprising: used to control the vibration of a rotating mode of a vibrating object. An inertial base (1) which makes it possible to install the equipment on the upper surface as a plate shape and has a certain weight; Fixed to the floor to support the inertial base (1), provided with a metal spring or air spring, a plurality of dustproof mount (2) to function to block vibration; And one or more torsion bar assembly (3) of the torsion bar bracket 311 is coupled to the inertial base (1), one end of the support rod (33) is coupled to the bottom; A vibration damper having a function of controlling a pitching vibration or a rolling vibration which is configured to include a vibration in a rotation mode.

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