RU2750951C1 - Earthquake protection platform - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: invention relates to mechanical engineering. The seismic protection platform contains a movable horizontal platform for mounting the protected equipment and a base. The platform and the base are movably connected to each other by means of devices for compensating for vertical movements, horizontal movements and anti-rollover devices. Horizontal displacement compensation devices contain ball bearing units. The upper and lower surfaces of the support nodes in contact with the ball have the shape of a concave sphere that turns into a conical surface. The tangent of the angle of inclination of the conical surface is less than the coefficient of sliding friction between the support surface and the ball. The materials of the ball and the surfaces of the support parts in the contact zone with the ball are heterogeneous.

EFFECT: increase in the service life of seismic protection platforms operating in conditions of intense industrial vibration is achieved.

4 cl, 4 dwg

Description

The invention relates to mechanical engineering, in particular to means of seismic and vibration protection of electrical, electronic, optical and other equipment, which is sensitive to industrial vibration, seismic and man-made influences acting on the equipment simultaneously in the vertical and horizontal directions.

State of the art

Known damping bases that protect equipment from seismicity and vibration, which contain a fixed base, a movable platform for attaching the protected equipment, a device for compensating vertical and horizontal movements, for example, a seismic impact platform according to patent RU No. 2178845, class. F16F 7/14, publ. 01/27/2002, which protects the equipment from both vertical and horizontal movements. The disadvantage of this technical solution is the fact that the platform has dimensions that exceed the dimensions of the protected equipment. In this connection, such platforms are difficult to use to protect cabinet sections.

The closest analogue (prototype) of the proposed invention is an earthquake protection platform containing a fixed base, a movable horizontal platform for fastening the protected equipment, a device for compensating for vertical and horizontal movements, a rollover protection device, while the movable horizontal platform is placed on the base through rolling units (RU No. 131108 U1, class F16F 7/14, publ. 08/10/2013). The specified platform effectively protects the equipment simultaneously in the vertical and horizontal directions, but at the same time has a limited resource of horizontal compensation when operating in an area of intense industrial vibration.

The limitation of the resource of the seismic protection platform according to the prototype is due to the fact that the metal rolling unit loses the ability to compensate for prolonged exposure to intense industrial vibration due to adhesive wear of the metal in the supporting surfaces, which results in damage (surface destruction, cracks, wear, etc.) ) surfaces that prevent the ball from rolling.

Disclosure of invention

The essence of the technical problem is as follows.

In modern industry, rolling bearings are often used as equipment supports. During operation, a rolling bearing is exposed to the complex effects of a number of factors that lead to premature destruction of bearing parts and their wear. As you know, adhesive wear is one of the most common and inevitable types of wear (Marchenko EA "On the nature of destruction of metals during friction", Moscow, Nauka, 1979). Wear occurs when foreign particles penetrate into the bearing or there is insufficient lubrication in the rolling bearings, while wear can also be the result of vibrations of a non-rotating bearing (SKF Catalog AB, 2002, St. Petersburg, “Damage to rolling bearings and their causes ").

Adhesive wear in the seismic protection platform is caused by the fact that the metal surfaces of the ball and supports operate under high contact pressure in a stationary-oscillatory mode on a very small area of the contact zone, while deformation and destruction of contact spots covered with oxides are formed due to pressure, and metal contact spots , which are freed from oxide films, are destroyed due to the periodic setting process. The diameter of the contact area in the rolling units, in which the ball rolls and, accordingly, the adhesive wear during industrial vibration, does not exceed 10 mm, because the amplitude of displacement at power frequency does not exceed 10 mm. At the same time, at a given amplitude, up to one billion fluctuations occur per year. The actual area of the bearing surfaces of the rolling unit is much larger due to the fact that it is required to provide equipment protection against impacts and seismic influences with a much larger amplitude of movement. However, since such influences are extremely rare, adhesive wear does not occur outside the displacement zone with a diameter of up to 10 mm, which is determined by the maximum displacement amplitude during industrial vibration.

The objective of the present invention is to eliminate adhesive wear in the rolling units and, as a consequence, to increase the reliability of the seismic protection platform by maintaining the operability of the horizontal movement compensation units under intense vibration and a significant weight of the protected equipment.

The technical result of the proposed solution is to increase the service life of seismic protection platforms operating in conditions of intense industrial vibration. Extension of the service life of seismic protection platforms is relevant for critical facilities with limited service areas and a long service life (for example, nuclear power plants), as well as facilities with built-in powerful sources of vibration (pumping stations, fans, air conditioners, etc.).

The technical result is achieved by the fact that the seismic protection platform contains a movable horizontal platform (6) for fastening the protected equipment (5) and a base (10), which are movably interconnected by means of vertical displacement compensation devices (7), horizontal displacement compensation devices (8) and rollover protection devices (9), while the horizontal displacement devices contain ball bearing units, in which there are upper and lower bearing parts movably connected through the ball, and the surfaces of the bearing parts in the contact zone with the ball have the shape of a concave sphere passing into a conical surface with an angle of inclination, the tangent of which is less than the coefficient of sliding friction between the bearing surface and the ball, while the materials of the ball and the surfaces of the bearing parts in the contact zone with the ball are dissimilar.

The ball is made of steel.

The surfaces of the bearing parts in the contact zone with the ball are made in the form of a solid non-metallic coating on a solid metal support, which prevents adhesive wear of the support metal under pressure.

The surfaces of the bearing parts in the contact zone with the ball are made in the form of ceramic inserts on a solid metal support, which prevent adhesive wear of the support metal under pressure.

The solution to the problem should be complex, since to compensate for horizontal displacements, it is necessary to ensure rigid contact between the supports and the ball, but the shape of the support surface must have a lower point where the ball returns after horizontal displacement due to gravity, but the tangential component of the gravitational force must be less than the sliding friction force of the ball, taking into account the friction force rolling to ensure 2 conditions:

Condition # 1:

K _tr.s - K _tr.k + tgα, where

K _tr.s - coefficient of sliding friction of the support and the ball;

K _tr.k - K _tr.k - coefficient of rolling friction of the support and the ball;

tgα is the tangent of the angle of inclination of the tangent to the support surface in the contact zone with the ball.

For example, for the case when the ball is made of steel ШХ15, and the supports are made of zirconium ceramics, then K _tr.s = 0.3; K _tr.k = 0.01, then tgα≤0.29, i.e. α≤16 °.

Condition # 2:

- adhesive wear should not increase the coefficient of rolling friction of the ball on the support, because this can lead to violation of condition No. 1, therefore, adhesive wear must be eliminated through the use of dissimilar contacting materials. The rolling friction coefficient significantly depends on the roughness of the contacting surfaces, which initially have a roughness of Ra = 2.5 - 0.25, but with adhesive wear, the roughness increases sharply due to periodic "seizure" and destruction of contact spots.

The task is also solved by introducing solid non-metallic materials into the contact zone of the supports of the horizontal compensation unit. It is the introduction of non-metallic materials into the contact zone that reduces the tendency to wear, since the forces of molecular adhesion at the interface of two parts (metallic and non-metallic) decrease due to the strong difference between the nature and structure of materials.

In addition, the task is solved by using a special form of supports, which, to increase the rigidity of the contact, has a spherical surface in the zone of compensation for displacements from industrial vibration, and has a conical shape in the zone of compensation for large displacements from seismicity and impacts.

Brief Description of Drawings

Fig. 1 - device for compensating horizontal movements (rolling unit);

FIG. 2 - horizontal displacement compensation device with additional ceramic liners;

FIG. 3 - device for compensating horizontal movements with a non-metallic hard coating;

FIG. 4 - seismic protection platform, general view.

Implementation of the invention

The seismic protection platform contains a fixed base (10), a movable horizontal platform (6) for fastening the protected equipment (5), a device for compensating for vertical movements (7) and a device for compensating for horizontal movements (8), a rollover protection device (9).

The vertical displacement compensation devices (7) are made in the form of compression support springs located and fixed on the horizontal displacement compensation devices (8).

The rollover protection device (9) consists of screws fixed on the movable platform (6) and on the stationary platform (10), which are connected by strong elastic ropes with an allowance of 100 mm. The ropes do not interfere with working movements when compensating for vibration with an amplitude of relative displacement up to 100 mm, but they prevent overturning from external accidental influence from the side of personnel if the relative movement is more than 100 mm.

Connection between platform (6) and horizontal movement devices

(8) is carried out through vertical displacement compensation devices (7), made in the form of compression support springs located and fixed on the horizontal displacement compensation devices (8).

The connection between the fixed base (10) and the horizontal displacement devices (8) is carried out through the rolling bearings made in the form of balls (2), while the balls roll between the movable supporting surface made in the form of a ceramic insert (3) and the fixed bearing surfaces made in the form of a spherical fixed surface, rigidly fixed on a fixed base (10). The number of balls is usually 4 pieces, but not necessary.

Horizontal displacement compensation devices are rolling units - ball bearing units, the design of which is disclosed in more detail in Fig. 1-3.

Ball bearing assemblies are bearing parts (top and bottom) that interact with each other through the ball so that they are displaced only in the horizontal direction. The supporting parts, in turn, have supporting surfaces (1).

Essentially, the rolling unit is formed by two bearing surfaces (1), which are in contact with the ball (2) and have the shape of a segment of a sphere (denoted by D in Figure 1), turning into a cone. The cone has an angle α of inclination, the tangent of which is less than the coefficient of sliding friction between the bearing surface and the ball, while the maximum diameter of the spherical surface segment must be greater than the amplitude of the maximum displacement during industrial vibration. To protect equipment subject to vibration with an acceleration amplitude of up to 10 m / s ² , the segment diameter is taken as 10 mm, for cases of equipment operation with industrial vibration more than 10 m / s ^2, the segment diameter is chosen from the ratio:

D≥A, where

D is the diameter of the spherical surface segment in mm;

А - vibration acceleration amplitude specified for the group of mechanical design for sinusoidal vibration in m / s ² .

For example, for a group of mechanical design M5 in accordance with GOST 17516.1: - the vibration acceleration amplitude for sinusoidal vibration is indicated as 20 m / s ² , therefore the diameter of the spherical surface segment must be ≥ 20 mm.

The angle "α" determines the spatial location of the generatrix of the conical surface.

To compensate for horizontal movements, it is necessary to ensure a firm contact between the supports and the ball. The shape of the support surface should have a lower point where the ball returns after horizontal displacement due to gravity, but the tangential component of the gravitational force should be less than the sliding friction force of the ball, taking into account the rolling friction force, in order to ensure 2 conditions:

Condition # 1:

K _tr.s - K _tr.k + tgα, where

K _tr.s - coefficient of sliding friction of the support and the ball;

K _tr.k - K _tr.k - coefficient of rolling friction of the support and the ball;

tgα is the tangent of the angle of inclination of the tangent to the support surface in the contact zone with the ball.

Condition # 2:

- adhesive wear should not increase the coefficient of rolling friction of the ball on the support, because this may lead to violation of condition # 1.

FIG. 2 shows an additional installation of liners (3) made of high-strength ceramics, for example, based on zirconium dioxide (see OOO Viral, catalog 2017 Bearings made of modern ceramics and hard alloys) or tungsten carbide (see Journal of Technical Physics, 2018, Volume 88, Issue 3 AS Savinykh et al., The effect of cobalt content on the strength properties of ceramics based on tungsten carbide.) for platforms with insignificant horizontal displacements of the rolling unit.

Ceramics based on zirconium dioxide are more technologically advanced, because the formation of the bearing surfaces of the rolling bearings is carried out by a widespread method

- pressing in molds at temperatures over 1300 ° C.

For platforms with significant horizontal displacements of the rolling unit, where it is impractical to install a ceramic liner due to the fragility of ceramics, the problem is solved by applying a solid non-metallic coating on the supporting surfaces (4), for example, nano-coatings based on cubic boron nitride (according to GOST 54473) or titanium nitride (see Proceedings of VIAM, DA Aleksandrov, STUDY OF WEAR-RESISTANT COATINGS BASED ON MULTICOMPONENT TITANIUM NITRIDES), as shown in Fig. 3.

The deposition of a solid non-metallic coating (4) on the supporting surfaces is most technologically advanced by the method of spraying boron nitrides or titanium nitrides in a vacuum.

The incorporation of solid non-metallic materials into rolling units is shown in FIG. 2 and FIG. 3.

The platform is installed between the floor and the protected equipment, therefore, when the floor begins to vibrate, the fixed base begins to vibrate with the floor (10). Floor vibration has a vertical component and a horizontal component. The task of the seismic protection platform is to screen the vibration of the floor using horizontal displacement compensation devices (8) and vertical displacement devices (7). The protected equipment has mass and corresponding inertia, therefore, horizontal displacements are compensated by the reciprocating horizontal rolling of the ball on the supporting surface of the stationary platform (10), and the vertical displacement is compensated by the compression-tension of the support springs by the vertical displacement compensation device. Thus, the protected equipment remains stationary due to its own inertia, i.e. shielded from vibration in the vertical and horizontal direction. The vertical compensation devices (7) are equipped with standard compression springs. And in horizontal compensation devices (8) there are a ball (2) and supporting surfaces.

It is due to the presence of spherical-conical bearing surfaces in the platform (1), as well as due to ceramic inserts (3) and / or non-metallic hard coating (4), that a long-term operation is ensured in conditions of intense industrial vibration and at the same time protects equipment from shocks and seismic effects with a significant amplitude of displacement.

Claims (4)

1. Seismic protection platform containing a movable horizontal platform (6) for fastening the protected equipment (5) and a base (10), which are movably connected to each other by means of vertical displacement compensation devices (7), horizontal displacement compensation devices (8) and protection devices against overturning (9), while the horizontal displacement compensation devices contain ball bearing units, in which there are upper and lower bearing parts movably connected through the ball, and the surfaces of the bearing parts in the contact zone with the ball have the shape of a concave sphere passing into a conical surface with an angle of inclination , the tangent of which is less than the coefficient of sliding friction between the bearing surface and the ball, while the materials of the ball and the surfaces of the bearing parts in the contact zone with the ball are dissimilar. 2. The seismic platform according to claim 1, characterized in that the ball is made of steel. 3. Seismic protection platform according to claim 1 or 2, characterized in that the surfaces of the bearing parts in the contact zone with the ball are made in the form of a solid non-metallic coating on a solid metal support, which prevents adhesive wear of the support metal under pressure. 4. Seismic protection platform according to claim 1, characterized in that the surfaces of the bearing parts in the contact zone with the ball are made in the form of ceramic inserts on a solid metal support, which prevent adhesive wear of the support metal under pressure.

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