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What is vibration?
Any mass being set in motion generates ENERGY. This occurs, for example, with earthquakes agitating huge masses which are able to destroy all human constructions, and with tree-shaking in order to harvest fruit without great effort.
These energies and their applications are calculated by means of vibration technology.
As a source of drive, applied VIBRATION TECHNOLOGY requires so-called vibration exciters, e.g. external vibrators. External vibrators feed circular or linear oscillatory energy in periodically changing directions in order to enter their force into the mass to be agitated.
With the help of these vibration exciters, vibratory technology allows for the excitation of the mass to be set to motion predominantly by means of periodical force and thus creates an oscillation with a determined frequency and amplitude.
When an unbalance is being generated, the excited mass follows a circular or elliptical path whereas a linear-type vibrator makes the mass move in a forward-and-backward direction.
There are three common types of energy for the drive of vibrators: pneumatic, electric, or hydraulic energy.
Important fields of application are:
Conveying The particles of the goods to be conveyed are pushed at a certain angle and in a way to create a succession of micro-size throwing movements to generate a conveying movement in one direction.
Dissolving Individual bulk goods particles are dissolved from a material aggregation by means of vibration. A frictional reduction makes sure the material is slackened and allows for the flowing of the material, respectively.
Compressing The reduction of friction among material particles results in a particle rearrangement. With the help of gravity, increased material density together with simultaneous de-aeration is obtained.
Places of application Among others, our external vibrators are employed in the following fields of industry: conveying, dosing, weighing, and sieving technologies, chemistry, mining, mechanical engineering, non-metallic mineral processing, metallurgical, packing, building construction and food industries, foundries, climate and de-dusting technologies.
The vibrators are in use with dosing, discharging, de-dusting, de-watering, de-airing, conveying, dissolving, slackening, compressing, mixing, sieving, sorting, cleaning, checking, feeding, etc.
The external vibrators can be mounted to: construction machines, silos, hoppers, conveying troughs, bowl feeders, vibrating conveyors, moulds, boarding units, vibrating tables, stone-shaping machines, surface dressing machines, vibratory boards, racks, and grates, filtering systems, downspouts, packing machines, and many others.
Types of actuation
Two types of vibration can be generated:
1. CIRCULAR VIBRATION by means of only one vibrator: in any case, the centrifugal force continuously changes its direction. The structure linked to the vibrator is moved elliptically.
There are three possible types of energy:
or hydraulic energy
2. LINEAR VIBRATION
a) by means of only on vibrator; There are mainly two types:
Pneumatic piston vibrator:
Electric: ELECTROMAGNETIC VIBRATOR:
b) by means of two circular vibrators turning in different senses of rotation and thus generating a one-sided directional vibration. These vibrators have to be solidly linked on the same level. The horizontal components are located on the same level and have the same, but converse impact. This means, only those components placed vertically to this level are being considered, i.e. added. The vibration takes place along this direction.
What’s the use of vibration?
In almost all fields of modern industry, there are examples of the continuously increasing importance of vibration technology and thus of the application of pneumatic or electric vibrators. The following listing of applications is to be considered for orientation purposes only as it is not exhaustive at all!
There are three predominant fields of application:
Fields of application
Main direction of power transmission
Generally speaking, conveying deals with forcing goods to be conveyed to move in one direction. The individual goods particles or pieces, respectively, are pushed at a certain angle in a way that chain-like micro-size throwing movements are generated:
These are the main applications of this technology:
SEPARATING (see also dissolving)
SIEVING, SCREENING, etc. …
… with all types of bulk goods: powder, nails, screws, wheat, vegetables, nuts, electric components, grains, clips, waste, hot cast parts, raw material parts, bottles, tins, cans, ampoules, pills, etc.
Dissolving / Slackening
On principle, dissolving and slackening is employed to dissolve individual parts from a material aggregation. This is achieved by reducing the friction between individual material particles or by eliminating strong adhesive forces.
The main applications with this technology are as follows:
DISCHARGING of silos, lorries, freight wagons, …
DE-DUSTING / DE-COKING of filters, piping, …
SLACKENING of sands, powders, flasks (foundries), bakings, …
Compressing serves for the rearrangement of particles within the material. Thus, friction among the material components is reduced (flowing process) and a maximum storage density and simultaneous de-aeration is obtained with the help of gravity or a superimposed load. The result: the air pore volume is minimised and the material is actually “compressed“.
Among others, densification of concrete is absolutely necessary:
Mounting of the external vibrator
Mounting of the external vibrator to the silo is an important item not only for the efficiency of the external vibrator but also for the integrity of the silo. In any case, the external vibrator must not be mounted directly to the wall of the silo or to the discharge funnel as material stress on these spots would be strong enough to crack the steel sheet there.
In addition, the working impact of the external vibrator would be limited to a very small area only. In order to avoid these negative effects, a stiffening device facilitating the mounting of the vibrator has to be installed on the funnel.
Welding (i.e. step-by-step welding) of a steel channel section has proven to be a simple and efficient way of stiffening.
Depending on the size of the funnel, the steel channel section should be a U 80 to U 120 type with a minimum length of one third of the funnel edge length. It is recommendable to attach the steel channel section up to the transversal cross-bracing and to weld it to the cross-bracing. The external vibrator is mounted vertically to the axis of the steel channel section. The sense of rotation of the vibrator should be chosen in a way that, on looking onto the vibrator from the side, the unbalances move from top to bottom on the funnel wall. As the vibrator is acting against the rigid axis of the steel channel section, the funnel wall and the stiffening device are prevented from damage and the vibration generated by the external vibrator is distributed more efficiently.
The screwed connections to fasten the external vibrator have to be re-tightened a short period after commissioning and their tight seating has to be checked in weekly inspection and maintenance intervals.
It is recommendable to secure the vibrator against unintended falling-down by means of a steel wire rope sufficiently dimensioned for the vibrator’s weight.
The external vibrators should only be switched on if the bulk material can flow off since, otherwise, an undesirable compression process may be started to exert unnecessary stress to the material inside the silo and to the weld seams on the mounting plate or the mounting section, respectively.
The main application fields of this technology are as follows:
1. As a rule, vibrators are firstly chosen with regard to their APPLICATION and secondly chosen with respect to their FREQUENCY. This is particularly true with electric and hydraulic vibrators.
On employing the pneumatic vibration technology, another method is required in most cases:
Predominantly, the formula: g x ∑ M is used.
IN THE CASE OF A PNEUMATIC VIBRATOR, THE FACTOR “g” IS TO BE DETERMINED. THE VIBRATOR ITSELF ADAPTS THE FREQUENCY – AND THE AMPLITUDE – TO THE STRUCTURE.
2. On working, pneumatic vibrators feature a loss of frequency. Therefore, the nominal centrifugal forces and frequencies indicated for idle running have to be corrected by recalculating them with the help of the following CORRECTION VALUES:
Normal frequency, i.e. from 1,000 up to 3,000 min-1 (this does not apply to air vibrators!) The frequency depends on the weight of the material particles to be moved. The higher the particle weight, the higher the frequency.
The amplitude depends on the stiffness of the structure. The following values can be deemed to be correct and suitable:
Frequencies in min-1 1.000 1.500 3.000
Amplitude in mm 3,5 – 11 1,5 – 5 0,4 – 2
Extreme amplitudesthat must not be exceeded in any case(please see item “Important information“): 25 12 3
Factor “g” = 1.8 to 2.2 of the total mass to be vibrated (mass of the material plus mass of the installation and of vibrators).
EXCEPTION: with horizontal vibration (e.g. sieving), these figures are halved in value.
Required force F:∑ F in daN = ∑ M x 1,8 bis 2,2
∑ M in kg = M of material + M of installation + M of the vibrators
Factor “g” depends on the particle weight of the material:With light particle weight: Y < 1 kg/dm3 g =< 1,8 Smaller graining, e.g. powder
With higher particle weight: Y > 1 kg/dm3 1,8 <= g <= 2,2 Smaller graining, e.g. powder
for transporting, dosing, feeding, weighing. Inclination of 5° to 30°
Direction of force
The inclination depends on the weight of the material particles to be moved. The higher the particle weight, the bigger the inclination.
Type of vibrations
Linear or directed vibrationsFrequency: adapt to Y
Mounting below the installation to be vibrated
2 units of electric vibrators
(maximum field of efficiency): 2 to 3.5 m per vibrator, depending on the stiffness of the structure.
In the case of applications involving two vibrators with different senses of rotation, the resultant is computed as follows:
Middle range from 1,500 to 3,000 min-1 (this does not apply to air vibrators!)The frequency depends on the type of the material particles to be moved.
The stickier the material, the lower the frequency.1,500 min-1 with wet or sticky materials3,000 min-1 with dry and relatively liquid materials
Depends on the frequency. The following values can be deemed to be correct and suitable:
Frequencies in min-1 1.500 3.000
Amplitude in mm 1,5 – 5 0,4 – 2Extreme amplitudes that must not be exceeded in any way (please see item “Important information“): 12 3,5
Factor “g” = 1.8 to 3.5 of the mass to be vibrated. This refers to the mass of material inside the silo to be vibrated only. The mass of the structure to be vibrated has to be determined with other applications.
There are POSSIBLE EXCEPTIONS with special applications Required force F: ∑ F in daN = ∑ M x 1,8 to 3,5
∑ M in kg = M of material in the cone of a silo or M of the structure
With dry, relatively liquid materials 1,8=< g =< 2
With wet, sticky materials 2 =< g =< 3,5
of silos, hoppers, containers, flasks, …
Direction of force
→ or ↗
In each case, the direction of force runs vertically to the structure to be vibrated.
Type of vibration
Mostly circular, but also directed vibration
Type of application
Power: in most case, Factor “g” = 2 is sufficient with a cone inclination up to some 30°. With regard to this value, please see the applicable correction values listed below. - Mounting is done on one third of the cone length. - The vibrator must be fastened to a steel-type reinforcement piece in order to have optimum effect of the vibration onto the material.
Mostly pneumatic vibrators of the turbine, ball, or piston types. Electric vibrators with bigger installations.(With dusty atmosphere, please see ATEX vibrator)
Slackening / cleaning / de-dusting
of filters, tubes, screens, flasks (foundries), …
Direction of force
→ vertically to the structure
Type of vibration
Mostly circular, occasionally directed vibration. Lower frequency: max. 1,500 min-1 with electric vibrators. Exception: tube cleaning which requires high frequency. With air vibrators = adapt the exact frequency Power: Factor “g”: 2 to 2.5 of total mass of the structure to be vibrated Factor “g”: 2.5 to 3 with flasks With horizontal vibration, these values are halved.
Generally speaking, there are two fields of application. With industry: For filling purposes on packing bulk goods, powder, graphite, quartz flour (in the glass industry), granulate, … For the flask preparation (foundries) With building construction: For the compressing of concrete
High frequency from 6,000 to 9,000 min-1 This does not apply to air vibrators. The frequency depends on the type of the material particles to be moved.
The smaller the grain size, the higher the frequency. In most cases: 6,000 min-1 with most materials and with concrete Up to 9,000 min-1 with very small grain-type materials or concrete
Exception: 3,000 min-1 with very dry concrete
Frequencies in min-1 6.000 9.000
Amplitude in mm 0,3 – 0,4 0,2 – 0,25
a) With industry: Factor “g” = 0.8 to 1.5 of the total mass to be vibrated. Mass of the material plus mass of the installation and the vibrators
0,8 =< g =< 1,5
b) With building construction: Very different depending on the forms and on the boarding.
Please contact our company!
Allows for up to 20% of additional cubic content
Direction of force
Type of vibration
Circular vibrationHigh frequency: 6 to 900 rpm depending on the graining of the material particles. The smaller the grain size, the higher the frequency
Mounting on the lower lateral part of the structure
Prior to the vibration
After the vibration
Compression of concrete
on vibrating tables: compression of stone blocks, flasks
(1) In this case the VT 24 could be replaced by another type of pneumatic vibrator (but only on the customer’s demand, as the turbine type only has advantages with regard to ball or roller vibrators): a) by a VK vibrator:
After correction, the output indicated for a VK has to amount to: 200 / 0.6 = 333.5 daN, i.e. 3,335 N. Checking the tables in the prospectuses shows that this output is granted by a VK26.
b) by a VR vibrator:
After correction, the output indicated for a VR has to amount to: 200 / 0.35 = 571.5 daN, i.e. 5,715 N. Checking the tables in the prospectuses shows that this output is granted by a VK78.
(2) In this case, and by a similar calculation, the V31 allows to be replaced:
a) by a VK vibrator:
266 / 0,6 = 443,5 daN, i. e. 4.435 N -> VK 26
b) by a VR vibrator:
266 / 0,35 = 760 daN, i. e. 7.600 N -> VR 78
(3) In this case, and by a similar calculation, the VT 16 allows to be replaced:
a) by a VK vibrator:
121 / 0,6 = 201 daN, i. e. 2.010 N -> VK 22
b) by a VR vibrator:
121 / 0,35 = 346 daN, i. e. 3.460 N -> VR 47
Information fpr the selection of the right type of vibration
Each vibrator type features advantages, disadvantages and application limits each customer should know well.