CS218812B1 - Equipment for compacting materials at resonance frequency - Google Patents

Abstract

The invention relates to a device for compacting materials at a resonant frequency or a frequency close to it. The device consists of an amplitude mixer mounted on a tread, connected by a connecting line to an indicator and a device for adjusting the eccentric moment simultaneously connected to a vibration exciter mounted in the tread. A pointer is attached to the indicator and a front drag stop is placed, placed on a scale, on which another stop is also attached. An electric circuit with a source and a light bulb, closed on the drag stop, can be connected to the pointer. The device according to the invention can be used in all compacting machines for which a change in frequency and eccentric moment is required.

Description

The invention relates to a device for compacting materials at or near a resonant frequency.

Currently known vibratory rollers are equipped with hydrostatic vibration drive, in which the excited frequency can be continuously or stepwise changed by means of a control pump designed to drive the vibration exciter. The value of the excited frequency is determined by experience and is usually in the range of 18 to 30 Hz for soils and in the case of bituminous materials usually in the range of 40 to 50 Hz. The magnitude of the centrifugal force, proportional to the magnitude of the eccentric moment and the excited frequency, can only be changed to a limited extent. An approximate choice of dynamic parameters of the vibratory roller (excited frequency and magnitude of centrifugal force) cannot achieve an effective compaction method, as each soil requires different values for these parameters.

These problems are overcome by a device according to the invention comprising an amplitude sensor mounted on the tread, interconnected by a connecting line with a pointer and an eccentric torque adjusting device connected simultaneously to a vibration exciter mounted in the tread. The pointer holds the pointer and is placed in front of the trailing stop, located on a scale on which the other stop is also attached. The hand can be connected to an electric circuit with a source and a bulb, closed at the trailing stop.

One embodiment of the invention is schematically illustrated in the drawings.

In Fig. 1, frequency characteristics at certain eccentric moments are plotted and compaction at resonant frequency is indicated.

Fig. 2 shows a resonant frequency compaction device with manual pump control and a device for adjusting the eccentric moment of the vibration exciter.

For material compaction at a resonant frequency w _r or a frequency close to that of the metallurgical force F at which the amplitude of oscillation A does not exceed the value given by the design of the machine (maximum value of oscillation amplitude A _max allowed by the elastic elements between tread 1 and machine frame 13), and a value corresponding to the compacted material. The whole compaction process can be explained in Fig. 1, where the dependence of the magnitude of the vibration amplitude A on the magnitude of the excited frequency ω is plotted. The frequency response curves in Fig. 1 are plotted for different eccentric moment sizes D _Vl and Dv ₂ (D = m .e where m - eccentric mass, e - eccentric center of gravity distance from the axis of rotation). The indicated vibration amplitude value, A _max, represents the maximum vibration value between the tread 1 and the frame 13. A _opt is the optimum amplitude value that is appropriate for a particular compacted material (determined by testing for each material separately). Since the vibration amplitude Ar of the frame 13 relative to the amplitude of vibration _B of the tread 1 in most cases is very small, can be considered the oscillation amplitude _B of the tread 1 and a vibration amplitude A between the tread 1 and the frame

13.

At the start of compaction, the vibration exciter is set to a minimum eccentric moment D _{in min} . The vibration exciter is starting and the vibration amplitude A _{B of the} tread 1 is increasing. Excitation frequency ω is increased until the increments amplitudes _B of the tread 1 are zero (in the case of further increasing the frequency ω would be excited by a decrease vibration amplitude _B of the tread 1. In this position a resonant frequency _ω Γ and corresponding amplitudes A _B of the tread 1, which is equal to the optimum amplitude of vibration and _opt drum 1 (the frequency characteristic for the eccentric moment DVJ Fig. Ij. If increasing the excited frequency ω optimal amplitudes and _opt tread 1, or a maximum vibration amplitude A _max tread 1 or the maximum vibration amplitude A _{max of the} tread 1, the eccentric moment D _{in the} tread 1 increases (the maximum vibration amplitude A _{max of the} tread 1 is reached when for a given material A _max has a value less than A _opt ). 1 shows the frequency response at an eccentric size. FIG Torque Dv _second increasing excited frequency ω to a point 1 leads to a certain lower value of amplitudes _B of the tread 1, after reaching a given value of _B is to be increased by means of the eccentric moment _D, the amplitude of the oscillations and _B up to an optimal vibration amplitude A _opt , which corresponds to the magnitude of the resonance frequency ω _Γ and the eccentric moment Dvj (in Fig. 1, point 2 j.

The apparatus implementing the described soil compaction method is comprised of a vibration exciter drive motor (not shown) 2, located in the tread 1 mounted in the frame 13. The hydraulic motor 2 is supplied with hydraulic fluid via a control pump 13. To the tread 1 (or any The machine 6 is fitted with a sensor 4 of magnitude A _{B of the} tread 1, which is connected to the pointer 6 by the connecting line 3. The pointer 6 has a trailing stop 8 and a stop 9 on the scale 14. Its upper end into the space in front of the trailing stop 8. The relative position of the pointer 7 and the trailing stop 8 is signaled by a bulb 11 located in the electrical circuit 10, whose contacts are connected to the pointer 7 and the trailing stop 8. the vibration exciter housed in the tread 1 is simultaneously connected to the eccentric adjusting device torque 3. Resistance218812

S and unsprung part of the machine have the same resonant frequency value ω _Γ , therefore the resonant frequency ω _Γ could be detected in the driver's cab (ie on the sprung part of the machine). The sensor 4 would be less stressed, but the pointer 6 would have to set the optimum oscillation amplitude A _{opt of the} frame 13 (based on the spring-loaded part of the machine) by the stop 9. Before starting compaction, the eccentric torque adjusting device 3 is set to a minimum eccentric torque D _min and the machine starts. Increasing the frequency ω pumped through the hydraulic motor 2 increases and the oscillation amplitude _Α β drum 1. The size of the oscillation amplitude and _FI tread 1 registers the sensor 4 and the needle 7 biases the pointer 6 in the clockwise direction. The needle 7 carries the trailing stop 8 with which it is in contact until it reaches the maximum oscillation amplitude A _max for the eccentric moment D _{in min} , ie to the resonant frequency ω _Γ . When the needle 7 is in contact with the trailing stop 8, the electrical circuit 10 is closed and the bulb 11 is lit. When the resonant frequency is exceeded, the vibration amplitude A _{B of the} tread 1 decreases and the pointer 7 is disconnected from the trailing stop 8 and thus the electrical circuit 10 is interrupted. By not illuminating the bulb 11, the operator is warned that 2 and it is necessary to increase the eccentric moment D _{in the} vibration exciter for adjusting the eccentric moment 3 so that the centrifugal force F at a constant frequency ω _Γ increases until the optimum vibration amplitude A _{opt for} tread 1 or the maximum vibration amplitude A _max is reached. The oscillation amplitude A _opt (or A _max ) is adjusted on the pointer 6 by the stop 9 to a value appropriate for the material before the oscillation amplitude A _{b of the} tread 1 begins to increase by the eccentric torque adjusting device 3. After reaching the optimum oscillation amplitude A _opt eventually A _max with magn The eccentric torque D _{v is} terminated and compaction is performed at these parameters.

The manual control of the control pump 15 can be converted to automatic (not shown) by inserting the servomotor in front of the control pump 15. The servomotor is connected to the electric circuit 10, in which a switch is inserted which switches off when the resonant frequency ω _Γ is reached. standstill servomotor. To increase the vibration amplitude A _{B of the} tread 1 by the eccentric torque D _v , an eccentric torque adjusting device 3 is used and can also be converted to automatic control. The eccentric torque adjusting device 3 is coupled to an indicator 6 which is configured as an automatic control member including an electrical circuit 10. Upon reaching the resonant frequency ω _{τ, the} automatic control automatically switches off the servomotor and turns on the eccentric torque adjusting device 3, which is switched off when the oscillation amplitude A _opi (or A _max ) is reached.

By using the device according to the invention, in particular in vibratory rollers, which are equipped with a vibration exciter having a variable eccentric moment and a variable frequency, a well-compacted material is obtained with a minimum number of passes. Machines equipped with this equipment increase the efficiency of compaction works and the quality of compaction. Their applicability for compaction of materials with substantially different properties is greatly expanded.

The device according to the invention can be used in all compaction machines in which the excited frequency and the eccentric torque can be varied, either continuously or with an acceptable graduation.

Claims (1)

Device for compaction of materials at or near a resonant frequency, consisting of a tread in which unbalances driven by a hydraulic motor with a pump are stored, characterized in that it consists of a sensor (4) of vibration amplitude amount (A _b ) mounted on the tread (1) interconnected connecting line (5) with indicator (6), OF THE INVENTION in which a pointer (7) located in front of the trailing stop (8) and a stop (9) are retained, optionally connected to the pointer (7) with an electrical circuit (10) with a source (12) and a bulb (11) the eccentric torque adjusting device (3) is connected at the same time to the trailing stop (8) and to the tread (1).