RU159615U1 - VIBROSTEND WITH HYDRAULIC VOLUME GENERATOR OF OSCILLATIONS - Google Patents

Abstract

A vibrostand with a hydrostatic oscillation generator, comprising a housing, an elastic shell, a threaded regulator, a plate, an eccentric shaft and an oscillator piston interacting with it; the elastic shell has a preliminary preload and is communicated by a hydraulic line with a one-sided hydraulic cylinder, the plunger of which is connected to a spring-loaded platform, characterized in that the threaded regulator is made in the form of two plates, which are pivotally connected to the body on one side and, on the other hand, are interfaced with spherical rod heads, moreover, the upper rod has a threaded connection with the bracket of the threaded regulator and is equipped with a rotary handle, the lower rod is rigidly connected to the bracket of the threaded regulator, and elastic shell without loosing state placed between the plates threaded regulator.

Description

The invention relates to a vibration technique, namely to vibration stands with hydrovolume excitation of vibrations.

Known hydraulic oscillation generator (SU No. 1421425, IPC B06B 1/18, published on 09/07/1988). It contains an eccentric shaft, plungers interacting with it, adjusting screws, plates, elastic shells pressed by plungers and corresponding plates associated with the adjusting screws, a switching device and a working body made in the form of a hydraulic cylinder.

Common signs of the claimed utility model with the considered analogue are an eccentric shaft, a plunger interacting with it, an adjusting screw, a plate, an elastic shell preloaded by a plunger and a plate connected with the adjusting screw and a hydraulic cylinder.

The specified hydraulic oscillation generator has the following disadvantage: it does not provide the ability to control the volumetric stiffness of the elastic shell and, thus, does not provide the ability to control the natural frequency of the oscillatory system formed by the hydraulic oscillation generator and hydraulic cylinder. Thus, in the oscillatory system formed by the hydraulic oscillation generator and the hydraulic cylinder, it is not possible to control the amplitude-frequency characteristic. Whereas the ability to control the amplitude-frequency characteristic is important for controlling the parameters of certain technological processes implemented by vibration.

Also known is a hydraulic vibrating stand (SU No. 1456243, B06B 1/18, published 02/07/1989). It contains a hydraulic oscillation generator with an eccentric shaft, plungers interacting with it, adjusting screws, plates, elastic shells pressed by plungers and corresponding plates associated with the adjusting screws, an actuator and a control system including hydraulic valves, pressure and pressure reducing valves, check valves, hydropneumatic accumulator and other elements of the hydraulic actuator.

Common features of an analogue with the claimed utility model are an eccentric shaft, a plunger interacting with it, an adjusting screw, a plate, an elastic shell preloaded by a plunger and a plate associated with the adjusting screw and an actuator.

The specified hydraulic vibration stand also has a drawback: it does not provide the ability to control the volumetric stiffness of the elastic shell of the hydraulic oscillation generator and, therefore, does not provide the ability to control the natural frequency, as well as the amplitude-frequency characteristic of the actuator. In it, the control of the amplitude and frequency of oscillations of the actuator is provided by a very complex control system, including control valves, pressure and pressure reducing valves, check valves, hydraulic pneumatic accumulator and other hydraulic actuator elements.

A prototype vibration test bench with a hydrostatic oscillation generator was adopted as a prototype (A. Nizhegorodov. A stand for dynamic tests of technical equipment in the amplitude-frequency modulation mode with a hydrostatic vibration drive / Construction and road machines. No. 10. - 2014. - P. 30-35). It contains a hydrostatic oscillator with a housing, including an elastic shell (high pressure sleeve), a threaded pre-tensioned shell regulator with a plate, an eccentric shaft and a generator piston interacting with it, while the elastic shell is pressed by a piston and a threaded regulator plate and communicated by a hydraulic line with a one-sided hydraulic cylinder . When the eccentric shaft rotates, the piston of the generator performs a reciprocating motion, alternately partially compressing-expanding the elastic shell and displacing the alternating volume of fluid from it, which excites the oscillations of the plunger of the one-sided hydraulic cylinder connected to the spring-loaded platform.

Common features of the prototype with the claimed utility model are a housing, an elastic shell, a threaded regulator, a plate, an eccentric shaft, an alternator piston interacting with it, a hydraulic line, a one-way hydraulic cylinder with a plunger connected to a spring-loaded platform.

The disadvantage of the prototype is the following. The threaded regulator with the plate together with the piston is able to change the preliminary preload of the elastic shell, which changes the magnitude of the alternating volume of the liquid displaced from it by the generator piston. Due to this, the amplitude of oscillations of the plunger with a spring-loaded platform of a one-sided hydraulic cylinder changes. At the same time, a change in the pretreated elastic shell leads to a change in its bulk stiffness, which causes an arbitrary change in the natural frequency of oscillations of the plunger with a spring-loaded platform of a one-sided hydraulic cylinder. But, the prototype does not provide the possibility of targeted and independent regulation over a wide range of volumetric stiffness of the elastic shell due to its static tightening, so the prototype does not provide the ability to control the natural frequency of vibrations and, as a result, does not provide the ability to control the amplitude-frequency characteristic of the plunger with a spring-loaded platform one-sided hydraulic cylinder.

The objective of the claimed utility model is aimed at providing a wide range of changes in the natural frequency of vibrations and, accordingly, at controlling the amplitude-frequency characteristics of the plunger with a spring-loaded platform of a one-sided hydraulic cylinder by static compression of the elastic shell and regulation due to this, the bulk stiffness of the elastic shell in a wide range.

The technical result of the utility model is to implement a wide range of control of the natural oscillation frequency and the amplitude-frequency characteristic of the plunger with a spring-loaded platform of a one-sided hydraulic cylinder by static preloading of the elastic shell due to the installation of a two-way threaded preload regulator on it.

The specified technical result is achieved in that the vibrostand with a hydrostatic oscillation generator, comprising a housing, an elastic shell, a threaded regulator, a plate, an eccentric shaft and an oscillator piston interacting with it; the elastic shell has a preliminary preload and is connected by a hydraulic line with a one-sided hydraulic cylinder, the plunger of which is connected to a spring-loaded platform, according to a useful model, the threaded regulator is made in the form of two plates, which are pivotally connected to the housing on one side and, on the other hand, are interfaced with spherical rod heads, moreover the upper rod has a threaded connection with the bracket of the threaded regulator and is equipped with a rotary handle, the lower rod is rigidly connected to the bracket of the threaded regulator, and the tight shell in the pressed state is placed between the plates of the threaded regulator. Therefore, it is possible to purposefully and independently control over a wide range of volumetric stiffness of the elastic shell due to its static compression by the plates.

The distinguishing features of the claimed utility model are a threaded regulator made in the form of two plates, pivotally connected to the housing on the one hand, and on the other hand rods mating with spherical heads, the upper rod has a threaded connection to the regulator bracket and is equipped with a rotary handle, the lower rod is rigidly connected with the bracket of the threaded regulator, and the elastic casing in the pressed state is placed between the plates of the threaded regulator.

The presence of distinctive features allows us to conclude that the claimed utility model meets the patentability condition of “novelty”.

In FIG. 1 shows a diagram of a vibrostand with a hydrostatic oscillation generator.

In FIG. Figure 2 shows experimental plots of the dependence of pressure P on the deformation volume of the cavity of the elastic shell of the volume ΔW.

In FIG. Figure 3 shows the cross sections of the elastic shell in an unstressed (left) state and preloaded to a value h (right) state.

In FIG. Figure 4 shows the dependence of the correction coefficient k ₀ on the compression h of the elastic shell.

Vibration stand with hydrostatic oscillation generator, shown in figure 1, contains a housing 1, an elastic shell 2 (high pressure sleeve), upper 3 and lower 4 plates and bracket 5 of the threaded regulator. The upper rod 6 with a spherical head is connected to the bracket 5 by a threaded connection and has a rotary handle 7. The lower rod 8 with a spherical head is rigidly connected (for example, pressed in) to the bracket 5. The spherical heads of the rods 6 and 8 are interfaced with spherical grooves in the upper 3 and lower 4 plates of a threaded regulator. The elastic shell 2 with its end sleeves 9 and 10 is inserted into the holes in the housing 1. The right nut is connected to the adapter 11, in which a threaded plug 12 for bleeding air is installed. The left nut through the hydraulic line 13 connects the elastic shell 2 with the cavity 14 of the single-sided hydraulic cylinder, the plunger 15 of which is connected to the spring-loaded springs 16 of the platform 17. The piston cylinder 18 is connected to the cavity 14, coupled to the cam 19, the shaft of which is connected on one side to the hydraulic motor 20 and on the other hand, with the flywheel 21. The eccentricity of the eccentric is a ₀ . An adapter 22 is attached to the cavity 14.

Points A and B in the adapters 11 and 22 are connected to the hydraulic system of the vibration stand.

A test vibrostand with a hydrostatic oscillation generator operates as follows, FIG. 1. Using a pump and regulating hydraulic equipment of the hydraulic system of the vibrostand (not shown in FIG.), An initial pressure P ₀ is created in the cavity of the elastic shell 2 and the cavity 14 of the one-sided hydraulic cylinder, which is then kept constant. Pressure P ₀ causes the plunger 15 to rise above its initial position to a level at which the efforts of the springs 16 will not restore the equilibrium state already relative to this new initial position. By the same pressure P _{0, the} cavity of the elastic shell will be expanded by compressing its rubber walls. When the eccentric 19 is rotated by the working hydraulic motor 20, the piston 18 reciprocates with an angular velocity ω. Flywheel 21 serves to smooth out the pulsation of the angular velocity ω. The volume of liquid 2w displaced over the full stroke of the piston 18, equal to 2 a ₀ , excites the oscillatory movement of the plunger 15 with the platform 17 (w is the amplitude value of the displaced volume of the liquid).

(н/м) упругой оболочки 2. При этом собственная частота колебательной системы ω₀ определяется выражением (рад/с):The vibration system of the vibrating stand is formed by a plunger 15 connected to the platform 17 having a total mass m (kg) and a total stiffness formed by the total stiffness with (n / m) of the springs 16 and reduced volumetric stiffness

(n / m) of the elastic shell 2. In this case, the natural frequency of the oscillatory system ω ₀ is determined by the expression (rad / s):

,

,

- площадь плунжера 15 (м²), c_об - объемная жесткость упругой оболочки (н/м⁵) 2.Where

- plunger area 15 (m ² ), c _rev - volumetric stiffness of the elastic shell (n / m ⁵ ) 2.

The volumetric rigidity of the elastic shell 2 is determined by the dependence of the pressure P (n / m ² ) in its cavity when a certain volume ΔW (m ³ ) is supplied to the cavity. For example, FIG. 1, if we fix the plunger 15 from moving and start moving the piston 18 upward, supplying fluid to the cavity of the elastic shell 2 (let it not be pressed by the plates 3 and 4 at this moment), then the larger the supplied volume ΔW, the greater the pressure in the cavity shell 2. In FIG. 2. Experimental graphs of the dependence of pressure P on the volume of deformation of the cavity of the elastic shell or, what is the same, on the value of the supplied volume ΔW are shown. The graphs were obtained by the example of a high-pressure hose with an inner diameter of d = 20 mm, the length of the rubber part L = 245 mm and the length of the pressed section B = 100 mm (see Fig. 1).

If the preload h (mm) is equal to the outer diameter of the sheath d _bun , then the elastic sheath 2 is not preloaded, and its inner section has the shape of a circle (the upper graph in Fig. 2). If the preload h of the elastic shell 2 is reduced to 30 mm, then to 28 mm, etc. (but not more than a certain minimum minimum value of h _min ), then the graphs of the pressure P versus the volume of deformation of the cavity ΔW of the elastic shell 2 change their slope and the bulk stiffness of the elastic shell 2 becomes less, since the same pressure increment P corresponds to an increasing the value of the volume of deformation of the cavity ΔW, FIG. 2 (ΔW ₂ > ΔW ₁ ). This is explained by the fact that in a free (not pressed) shell or high pressure sleeve under pressure loading, the inner rubber layer (Fig. 3) mainly has the ability to deform, since the metal cord of the sleeve does not allow the outer rubber layer to deform. The sleeve, compressed to a value of h, has supporting pads (Fig. 3, right), the outer layers of which are deformed when pressure is applied and participate in the formation of volumetric stiffness, moreover, with decreasing h, the width of the supporting pad increases and, therefore, most of the outer rubber layer is involved in the formation of volumetric stiffness of the elastic shell 2 (high pressure sleeve).

The upper graph for an unstressed elastic shell 2 with h = d _nar = 32 mm in FIG. 2 can be described with high accuracy by the empirical expression:

where k ₁ and k ₂ are empirical coefficients (for an unstressed high-pressure hose with parameters, for example, d = 20 mm and L = 245 mm), equal to k ₁ = 62.6 · 10 ¹⁰ (n / m ⁵ ) and k ₂ = 63.910 ¹⁶ (n / m ⁸ ).

Considering that the preload of the elastic shell 2 affects the slope of the graphs of the pressure P as a function of the deformation volume of the cavity of the elastic shell, FIG. 2, in the expression (1) we introduce the correction factor to ₀ :

For each of the graphs in FIG. 2, corresponding to the preload h, the values of the correction coefficient are determined, table 1.

For clarity, the dependence of the correction coefficient k ₀ on the preload h is shown in graph form in FIG. 4: the stronger the elastic shell 2 is pressed, the smaller the coefficient k ₀ . For example, with h = 22 mm, the correction factor will be approximately 0.4.

The bulk rigidity of the elastic shell 2 is determined by differentiating the expression (2):

.

.

и иметь размерность н/м, что соответствует размерности жесткости обычной пружины.The resulting formula has a dimension of n / m ⁵ . Being reduced to the area of the plunger 15, the rigidity of the elastic shell 2 will be equal to

and have a dimension n / m, which corresponds to the dimension of stiffness of a conventional spring.

Then the natural frequency of the oscillatory system ω _{0 is} determined by the expression (rad / s):

It can be seen from the formula that the natural frequency of the oscillatory system of the vibrating stand formed by the plunger 15, platform 17 and springs 16 depends on the correction factor to ₀ (see table 1 and Fig. 4) and, therefore, on the preliminary compression of the elastic shell 2.

When the eccentric 19 rotates with an angular frequency ω equal to the natural frequency of the oscillatory system ω ₀ , a resonance begins, accompanied by a multiple increase in the amplitude of the oscillations of the platform 17. The magnitude of the amplitude depends on how precisely the frequencies ω and ω ₀ coincide. By changing the preload h of the elastic shell 2, it is possible to bring ω ₀ to ω or, conversely, to remove ω ₀ from ω, adjusting the resonance amplitude and, thus, controlling the amplitude-frequency characteristic.

Thus, the technical result of the utility model is achieved — expanding the control range of the natural frequency of vibrations and, therefore, the amplitude-frequency characteristic of the vibration system of the vibration bench, formed by a plunger with a platform and springs, by preliminary static preloading of the elastic shell due to the threaded preload regulator.

Claims (1)

A vibrostand with a hydrostatic oscillation generator, comprising a housing, an elastic shell, a threaded regulator, a plate, an eccentric shaft and an oscillator piston interacting with it; the elastic shell has a preliminary preload and is connected by a hydraulic line with a one-sided hydraulic cylinder, the plunger of which is connected to a spring-loaded platform, characterized in that the threaded regulator is made in the form of two plates, which are pivotally connected to the body on one side and, on the other hand, are interfaced with spherical rod heads, moreover, the upper rod has a threaded connection with the bracket of the threaded regulator and is equipped with a rotary handle, the lower rod is rigidly connected to the bracket of the threaded regulator, and elastic shell without loosing state placed between the plates threaded regulator.

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