ECCENTRIC MASS VIBRATING SYSTEM

Abstract

An eccentric mass vibrating system comprising: a first motor having a first shaft; a first eccentric mass connected to said first shaft; a second motor having a second shaft; a second eccentric mass connected to said second shaft; said first motor and said second motor are adapted to be associated with an object to be vibrated; said first motor and said second motor being electrically adjustable so as to arrange said first eccentric mass and said second eccentric mass at a predefined angle therebetween; said first motor and said second motor being adapted to be positioned on an object to be vibrated; characterised in that it comprises: at least one sensor associated with said object to be vibrated, and a control computer of said system adapted to modify said predefined angle if the value measured by said sensor exceeds a predefined value.

Claims

1. An eccentric mass vibrating system comprising: a first motor having a first shaft; a first eccentric mass connected to said first shaft; a second motor having a second shaft; a second eccentric mass connected to said second shaft; said first motor and said second motor are adapted to be associated with an object to be vibrated; said first motor and said second motor being electrically adjustable so as to arrange said first eccentric mass and said second eccentric mass at a predefined angle therebetween; said first motor and said second motor being adapted to be positioned on an object to be vibrated; characterised in that it comprises: at least one sensor associated with said object to be vibrated; a control computer of said system adapted to modify said predefined angle if the value measured by said sensor exceeds a predefined value.

2. The system according to claim 1 characterised in that said first motor and said second motor are made to rotate from a first speed to a second speed.

3. The system according to claim 1 characterised in that said at least one sensor is a sensor adapted to measure the vibrations of said object to be vibrated.

4. The system according to claim 1 characterised in that said at least one sensor is a sensor adapted to measure the noise generated by said object to be vibrated.

5. The system according to claim 1 characterised in that said at least one sensor is a sensor adapted to measure the current absorbed by said first motor.

6. The system according to claim 1 characterised in that said first eccentric mass and said second eccentric mass are equal in terms of dimension, form and weight.

7. The system according to claim 1 characterised in that said first motor is a stepper motor or a brushless motor.

8. The system according to claim 1 characterised in that said first motor and said second motor are fixed to a base; two structures are fixed perpendicularly on said base; and two bearings are fixed to said two structures fixed perpendicularly to support said first shaft and said second shaft respectively.

9. A method for the control of an eccentric mass vibrating system having a first motor with a first eccentric mass and a second motor with a second eccentric mass; comprising the steps of: positioning said system on the object to be vibrated; associating at least one sensor with the object to be vibrated; positioning said first eccentric mass and said second eccentric mass phase shift from each other by a first predefined angle; varying the speed of said first motor and said second motor between a first number of revolutions and a second number of revolutions; checking the value measured by said at least one sensor; varying said first predefined angle if the value measured by said at least one sensor exceeds a predefined value.

10. The method according to claim 9 characterised in that said at least one sensor is an accelerometer or an ammeter or a microphone.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The characteristics and the advantages of the present invention will be evident from the following detailed description of a practical embodiment thereof, illustrated by way of non-limiting example in the attached drawings, in which:

[0039] FIG. 1 shows schematically a block diagram of an eccentric mass vibrating system, in accordance with the present invention;

[0040] FIG. 2 shows schematically two motors with relative eccentric weights of an eccentric mass vibrating system, in accordance with the present invention;

[0041] FIG. 3 shows schematically the eccentric weights of an eccentric mass vibrating system, in accordance with the present invention;

[0042] FIG. 4 shows schematically the eccentric weights in the position of maximum eccentricity, of an eccentric mass vibrating system, in accordance with the present invention;

[0043] FIG. 5 shows schematically the eccentric weights in a neutral position, of an eccentric mass vibrating system, in accordance with the present invention.

DETAILED DESCRIPTION

[0044] Referring to the attached figures, an eccentric mass vibrating system 10, in accordance with the present invention, comprises a vibrator 11, a first drive circuit 12 of the vibrator 11, a second drive circuit 13 of the vibrator 11 and a control computer 14 of the eccentric mass vibrating system 10.

[0045] The vibrator 11 comprises a first electric motor 21 and a second electric motor 22, preferably stepper motors or brushless motors that allow precise quick movements with compact overall dimensions and great versatility.

[0046] The first electric motor 21 and the second electric motor 22 are fixed on a common base 23, which will be fixed to the object to be vibrated. The motors 21 and 22 are preferably positioned with the respective shafts 24, 25 opposite each other (but separate from each other) and preferably supported by two bearings 26 fixed on two structures 27 fixed perpendicularly on the common base 23, and joined to each other at the top to give the base 23 greater solidity.

[0047] Preferably, as shown in the figures, the shafts 24 and 25 are positioned on the same axis. But they can be opposite each other, adjacent or in different positions.

[0048] The motors 21 and 22 could be fixed to the base 23 also opposite each other with the respective shafts 24 and 25 facing outwards. The component to be vibrated, normally made of electrowelded composite fabrication work, can act as a base for direct fixing of the motors 21 and 22, without the use of the base 23.

[0049] On each shaft 24 and 25, a respective bar 28 and 29 is positioned to form the eccentric mass.

[0050] The two bars 28 and 29 can have enlargements or expansions to reach the desired weight, and are equal in terms of dimension, form and weight.

[0051] The first drive circuit 12 drives the first electric motor 21, and the second drive circuit 13 drives the second electric motor 22, and the control computer 14 controls the drive circuits 12 and 13 and the whole of the eccentric mass vibrating system 10 which comprises various sensors for control of the vibrator 10, for example current sensors (ammeter) to detect the value of the current absorbed by the motors 21 and 22 and vibration sensors (accelerometers) which will be positioned on the object to be vibrated and will provide the feedback of the excitation applied, for example, by observing the amplitude of the vibrations as well as acoustic sensors (microphones) to be positioned in the vicinity of the object to be vibrated to monitor the value of the noise generated by the object to be vibrated, and frequency meters or spectrum analyzer.

[0052] The motors 21 and 22 are preferably stepper motors or brushless motors, with which it is possible to adjust, by means of the control computer 14, the phase of each of them, namely position the shaft 24 and 25, and consequently the bars 28 and 29, in the required position.

[0053] In this way it is possible to position, independently of each other, the bars 28 and 29 in every position from 0° to 360°. Consequently it is possible to position the bars 28 and 29 with an angle a as required, as shown in FIG. 3.

[0054] It is therefore possible to choose an angle a between the two bars 28 and 29 from 0°, in the position of maximum eccentricity, as in FIG. 4, to an angle a between the two bars 28 and 29 at 180°, in position, as in FIG. 5.

[0055] Both the motors 21 and 22 can be adjustable, but to simplify the electronics, the phase of only one of the two motors is adjusted. In this case one motor is of the stepper or brushless type, therefore having adjustable phase, while the other can be an electric motor of any type.

[0056] Thanks to the present invention it is therefore possible to choose the amount of eccentricity, namely the unbalance, of the vibrator 10 automatically.

[0057] The procedure is carried out as follows. The object to be vibrated is positioned on elastic load bearings, to isolate the object from the ground and vibrate it more easily.

[0058] The vibrator is positioned, oriented and locked securely on the object to be vibrated.

[0059] The vibration sensor is positioned on the part to be vibrated and/or the other sensors in the most appropriate positions.

[0060] The unbalance of the vibrator is adjusted, by adjusting the phase of at least one of the two motors 21 and 22, then the bars 28 and 29 are positioned with a predefined angle a between them. Initially the phase shift is maximum and equal to 180°.

[0061] The speed of the two motors 21 and 22 is varied within a predefined speed range, for example between 1500 and 6000 revolutions per minute, corresponding to vibrations of the part to be vibrated at different frequencies, at the maximum energy transmittable, maintaining fixed the predefined angle a between the bars 28 and 29.

[0062] The resonance or the resonances of the part to be vibrated are found.

[0063] In the case of a resonance in which the vibrations and/or the noise and/or the motor absorption is excessive and exceeds predefined preference values, the phase shift between the bars 28 and 29 is reduced, by means of the control computer 14, and in such a way as to reduce the excesses of the detected value to acceptable levels and the scan is repeated.

[0064] As soon as possible the phase shift between the bars 28 and 29 is increased again to avoid losing any resonance values.

[0065] At the end of the scan, the various resonance frequencies of the object to be vibrated have been obtained, corresponding to particular values of the motor revolutions, and the relative maximum phase shift angles between the bars 28 and 29 which allow treatment without excessive vibration, noise and absorption values.

[0066] The treatment cycle of the object to be vibrated is then started, in automatic mode, applying to the bars 28 and 29 the maximum phase shift values possible for each frequency to be treated.

[0067] The eccentric mass vibrating system with adjustment of the unbalance of the eccentric masses thus conceived is subject to numerous modifications and variations, all falling within the scope of the inventive concept; furthermore, all the details can be replaced by technically equivalent elements.