CA1139267A - Method for regulating the throw angle of a vibrating sieve or feeder - Google Patents
Method for regulating the throw angle of a vibrating sieve or feederInfo
- Publication number
- CA1139267A CA1139267A CA000334865A CA334865A CA1139267A CA 1139267 A CA1139267 A CA 1139267A CA 000334865 A CA000334865 A CA 000334865A CA 334865 A CA334865 A CA 334865A CA 1139267 A CA1139267 A CA 1139267A
- Authority
- CA
- Canada
- Prior art keywords
- motors
- feeder
- gravity
- balance
- center
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65G—TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS
- B65G27/00—Jigging conveyors
- B65G27/10—Applications of devices for generating or transmitting jigging movements
- B65G27/32—Applications of devices for generating or transmitting jigging movements with means for controlling direction, frequency or amplitude of vibration or shaking movement
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
- B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
- B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
- B06B1/10—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of mechanical energy
- B06B1/16—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of mechanical energy operating with systems involving rotary unbalanced masses
- B06B1/161—Adjustable systems, i.e. where amplitude or direction of frequency of vibration can be varied
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
- B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
- B07B1/00—Sieving, screening, sifting, or sorting solid materials using networks, gratings, grids, or the like
- B07B1/42—Drive mechanisms, regulating or controlling devices, or balancing devices, specially adapted for screens
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Combined Means For Separation Of Solids (AREA)
- Jigging Conveyors (AREA)
- Eye Examination Apparatus (AREA)
- Vehicle Body Suspensions (AREA)
- Gyroscopes (AREA)
Abstract
APPLICANT: MORGARDSHAMMAR AKTIEBOLAG
TITLE: METHOD FOR REGULATING THE THROW ANGLE OF A
VIBRATING SIEVE OR FEEDER
ABSTRACT OF THE DISCLOSURE
In a sieve or feeder there are two out-of-balance weights rotating in opposite directions, each driven by its own motor, preferably of asynchronic type. Together they achieve a shaking movement, in which the out-of-balance weights, by mechanical coupling, will normally force the motors to keep such a speed and phase that they will be synchronized. An elliptical stroke can be obtained thereby if the out-of-balance weights are different and if the center of gravity of the shaken mass is suitably placed. The direction of stroke can be altered by changing the ratio between the powers supplied to the two motors.
TITLE: METHOD FOR REGULATING THE THROW ANGLE OF A
VIBRATING SIEVE OR FEEDER
ABSTRACT OF THE DISCLOSURE
In a sieve or feeder there are two out-of-balance weights rotating in opposite directions, each driven by its own motor, preferably of asynchronic type. Together they achieve a shaking movement, in which the out-of-balance weights, by mechanical coupling, will normally force the motors to keep such a speed and phase that they will be synchronized. An elliptical stroke can be obtained thereby if the out-of-balance weights are different and if the center of gravity of the shaken mass is suitably placed. The direction of stroke can be altered by changing the ratio between the powers supplied to the two motors.
Description
~13g26~
METHOD FOR REGULATING THE THROW ANGLE OF A VIBRATING SIEVE OR FEEDER
The invention relates to a method which is usable in those driving means for achieving shaking or oscillating movements, in which two out-of-balance weights are rotated in opposite directions around individual shafts and are provided with separate drive motors.
There are two types of this sort of driving unit. In one of them, which has been known for a long time, the two out-of-balance weights are of the same size and weight. A theoretical treatment of this case is to be found in Aufbereitungs-Technik for 1976, pages 108-114, for example. In this first type of drive unit, a linear, reciprocal movement can be obtained along the mid-point normal to a straight line connecting the two shafts.
The other type of drive unit was invented by us and is described in United States Patent No. 4,212,731 of Wallin, issued July 15, 1980. According to this invention, an elliptical stroke is obtained by making the out-of-balance weights of different size, under the precondition that the center of gravity of the oscillating system lies essentially on an Appollonios' circle to the axes of rotation, so determined that the ratio of the distances from the center of gravity to the axes of rotation is inversely proportional to the products of the weights of the respective oscillation P~ - 1 -~39~67 masses and their mean distance to the respective axis of rotation.
The latter invention was developed from an in-depth theoretical study of a previously known system with two different sized oscillation masses, compulsorily coupled together with a toothed gearing. The research began with a calculation of the reaction moments on the shafts to the out-of-balance weights, where, inter alia, the following result was obtained:
(2ml rl~)2 sina cosa (a sin ~t + b cos ~t)2 Ml-M2 = '--Y (1) where Ml and M2 are the reaction moments around the respective rotational axes; ml and rl are the weight of one out-of-balance weight and its distance from its rotational axis, respectively; a and b are the Cartesian coordinates in a Cartesian system of coordinates with the center of gravity of the oscillating system as the origin;
a is the angle between the direction of stroke and a line from the origin to the point (a,b); ~ is the angular frequency for the rotation of the out - of-balance masses;
and y is the mass moment of inertia of the system.
Ml-M2 is then a restoring moment which acts to return the system to the direc-tion a = 0.
The basic idea which is the first step in the present invention is the insight that the equation (1) is valid even when reversed so that if an external moment is applied, the throwing angle is affected -to a corresponding degree, that is to say, artificially it is possible to achieve a value for a which is non-zero. A precondition for balance in such a system is that the work of the external moment be equal to the work of the sychronizing moment. The cycle for the synchronizing moment is 2rr. If we integrate Ml-M2 over one revolution, we obtain from equation (l):
METHOD FOR REGULATING THE THROW ANGLE OF A VIBRATING SIEVE OR FEEDER
The invention relates to a method which is usable in those driving means for achieving shaking or oscillating movements, in which two out-of-balance weights are rotated in opposite directions around individual shafts and are provided with separate drive motors.
There are two types of this sort of driving unit. In one of them, which has been known for a long time, the two out-of-balance weights are of the same size and weight. A theoretical treatment of this case is to be found in Aufbereitungs-Technik for 1976, pages 108-114, for example. In this first type of drive unit, a linear, reciprocal movement can be obtained along the mid-point normal to a straight line connecting the two shafts.
The other type of drive unit was invented by us and is described in United States Patent No. 4,212,731 of Wallin, issued July 15, 1980. According to this invention, an elliptical stroke is obtained by making the out-of-balance weights of different size, under the precondition that the center of gravity of the oscillating system lies essentially on an Appollonios' circle to the axes of rotation, so determined that the ratio of the distances from the center of gravity to the axes of rotation is inversely proportional to the products of the weights of the respective oscillation P~ - 1 -~39~67 masses and their mean distance to the respective axis of rotation.
The latter invention was developed from an in-depth theoretical study of a previously known system with two different sized oscillation masses, compulsorily coupled together with a toothed gearing. The research began with a calculation of the reaction moments on the shafts to the out-of-balance weights, where, inter alia, the following result was obtained:
(2ml rl~)2 sina cosa (a sin ~t + b cos ~t)2 Ml-M2 = '--Y (1) where Ml and M2 are the reaction moments around the respective rotational axes; ml and rl are the weight of one out-of-balance weight and its distance from its rotational axis, respectively; a and b are the Cartesian coordinates in a Cartesian system of coordinates with the center of gravity of the oscillating system as the origin;
a is the angle between the direction of stroke and a line from the origin to the point (a,b); ~ is the angular frequency for the rotation of the out - of-balance masses;
and y is the mass moment of inertia of the system.
Ml-M2 is then a restoring moment which acts to return the system to the direc-tion a = 0.
The basic idea which is the first step in the present invention is the insight that the equation (1) is valid even when reversed so that if an external moment is applied, the throwing angle is affected -to a corresponding degree, that is to say, artificially it is possible to achieve a value for a which is non-zero. A precondition for balance in such a system is that the work of the external moment be equal to the work of the sychronizing moment. The cycle for the synchronizing moment is 2rr. If we integrate Ml-M2 over one revolution, we obtain from equation (l):
2~ (2ml rl ~) (a +b ) ~r I (Ml-M2)d~t = sin 2a =
o 2 y = CONST. sin 2a. (2 s 11392i7 One can see from this that a numerical increase or decrease in an external moment results in an increase or decrease in ~ up to the limit ~45 , whereafter stability can no longer be expected.
In the absence of the external moment, as the description of the invention in United States Patent No. 4,212,731 reveals, a purely translational shaking movement is obtained, without rotation (tilting). The introduction of an external moment disturbs this "equilibrium", and a superimposed tilting movement is obtained. However, it has been shown both theoretically and in practice that this is of completely negligible size.
It is now possible to superimpose an "external" moment in many dif-ferent ways. For example, it is theoretically possible by using springs or weights fastened to the screening box, to apply a couple of forces which tends to turn the suspended mass. However, we feel that it is most advantageous to act on the two motors which drive the out-of-balance weights.
The present invention provides a method for regulating the throw angle of a vibrating device such as a sieve or feeder of the type which has a drive means with out-of-balance means around two shafts which are parallel to each other, characterized in that the two out-of-balance means are of different dim-ensions, are driven by individual motors and have their shafts arranged in relation to the center of gravity of the device in such a way that the center of gravity lies on an Apollonios' circle to the two shafts, so determined that the ratio of the di6tances from the center of gravity to the axes of rotation is inversely proportional to the products of the out-of-balance weights of the respective out-of-balance means and their mean distance to the respective axis of rotation, the throw angle being affected by changing the power of one of the motors in relation to that of the other.
The regulation can include the possibility of compensating for uneven load due to uneven distribution of the material to be screened.
B - 3 _ ~13~Z67 The invention will now be described with reference to an embodiment shown in the drawings.
Figure 1 shows a perspective view of a horizontal sieve.
Figure 2 shows a schematic sectional view of one oE the out-of-balance devices in the sieve according to Figure 1.
The sieve in Figure 1 consists of a screen box 1, with a first screening level 7 and a second screening level 8, which is suspended on a bed 9 by means of springs 2.
Two motors 3 each drive one of a pair of out-of-balance weight means 5, each pair mounted in a dust-proof casing with an intermediate shaft. As can be seen from the detailed drawing in Figure 2, each motor drives, via a belt transmission 11, mounted in a protective casing 6 (Figure 1), and via flexible couplings 12 (in casing 4), a shaft with out-of balance weights 10 pairwise rotatably journalled in the walls of the screening box 1. The motors and the belt transmissions are rigidly joined to the bed 9 and thus do not vibrate. Movement in the drive train is accommodated by the flexible couplings.
The inventive effect is achieved by virtue of the fact that the motors 3, which are short-circuit asynchronous motors with the same rated speed, can be imparted different propelling forces. If the motors receive current directly from a common alternating current mains source, the oscillation masses 10 (Figure 2) in the two units, which rotate in opposite directions, will be synchronized and an elliptical thrust will be obtained. Through a transfornler unit of a type well-known to the person skilled in the art (either stepwise or continuously variable), the supply voltage to one of the motors can be reduced.
Since the two motors are loaded, they will have a certain lag in relation to the synchronous r.p.m. Due to the difference in voltage, the driving force of one of the motors will drop, and the lag in that motor will increase somewhat.
-- ~I --.~
1139~7 (Other types of motors and other control mechanisms which are well-known to the personskilledin the art are of course conceivable.) It has been shown, quite surprisingly at first, that it is possible to obtain with this simple method a displacement of the direction of the stroke, up to about 45 in either direction, depending on which of the two motors has its supply voltage reduced.
The theoretical explanation above is rather sketchy, but we did not feel it necessary to have a more careful calculation of the dynamic relations.
We were satisfied with finding, by tests with models (regardless of the explan-ation one wishes to give to the phenomena) that the inventive effect is achieved if one proceeds as specified in the accompanying claims.
The advantages of the invention are apparent. In both a feeder anda sieve, the transport speed can be varied as needed. It is also possible to compensate for uneven load.
- ~a B
sy optimizing the throw angle it is also possible to obtain an improved screening effect and control the screening so that the screen meets the material, when falling down, in such a way that the material and the screen have opposite movements, thus achieving the best sorting effect and avoiding plugging.
o 2 y = CONST. sin 2a. (2 s 11392i7 One can see from this that a numerical increase or decrease in an external moment results in an increase or decrease in ~ up to the limit ~45 , whereafter stability can no longer be expected.
In the absence of the external moment, as the description of the invention in United States Patent No. 4,212,731 reveals, a purely translational shaking movement is obtained, without rotation (tilting). The introduction of an external moment disturbs this "equilibrium", and a superimposed tilting movement is obtained. However, it has been shown both theoretically and in practice that this is of completely negligible size.
It is now possible to superimpose an "external" moment in many dif-ferent ways. For example, it is theoretically possible by using springs or weights fastened to the screening box, to apply a couple of forces which tends to turn the suspended mass. However, we feel that it is most advantageous to act on the two motors which drive the out-of-balance weights.
The present invention provides a method for regulating the throw angle of a vibrating device such as a sieve or feeder of the type which has a drive means with out-of-balance means around two shafts which are parallel to each other, characterized in that the two out-of-balance means are of different dim-ensions, are driven by individual motors and have their shafts arranged in relation to the center of gravity of the device in such a way that the center of gravity lies on an Apollonios' circle to the two shafts, so determined that the ratio of the di6tances from the center of gravity to the axes of rotation is inversely proportional to the products of the out-of-balance weights of the respective out-of-balance means and their mean distance to the respective axis of rotation, the throw angle being affected by changing the power of one of the motors in relation to that of the other.
The regulation can include the possibility of compensating for uneven load due to uneven distribution of the material to be screened.
B - 3 _ ~13~Z67 The invention will now be described with reference to an embodiment shown in the drawings.
Figure 1 shows a perspective view of a horizontal sieve.
Figure 2 shows a schematic sectional view of one oE the out-of-balance devices in the sieve according to Figure 1.
The sieve in Figure 1 consists of a screen box 1, with a first screening level 7 and a second screening level 8, which is suspended on a bed 9 by means of springs 2.
Two motors 3 each drive one of a pair of out-of-balance weight means 5, each pair mounted in a dust-proof casing with an intermediate shaft. As can be seen from the detailed drawing in Figure 2, each motor drives, via a belt transmission 11, mounted in a protective casing 6 (Figure 1), and via flexible couplings 12 (in casing 4), a shaft with out-of balance weights 10 pairwise rotatably journalled in the walls of the screening box 1. The motors and the belt transmissions are rigidly joined to the bed 9 and thus do not vibrate. Movement in the drive train is accommodated by the flexible couplings.
The inventive effect is achieved by virtue of the fact that the motors 3, which are short-circuit asynchronous motors with the same rated speed, can be imparted different propelling forces. If the motors receive current directly from a common alternating current mains source, the oscillation masses 10 (Figure 2) in the two units, which rotate in opposite directions, will be synchronized and an elliptical thrust will be obtained. Through a transfornler unit of a type well-known to the person skilled in the art (either stepwise or continuously variable), the supply voltage to one of the motors can be reduced.
Since the two motors are loaded, they will have a certain lag in relation to the synchronous r.p.m. Due to the difference in voltage, the driving force of one of the motors will drop, and the lag in that motor will increase somewhat.
-- ~I --.~
1139~7 (Other types of motors and other control mechanisms which are well-known to the personskilledin the art are of course conceivable.) It has been shown, quite surprisingly at first, that it is possible to obtain with this simple method a displacement of the direction of the stroke, up to about 45 in either direction, depending on which of the two motors has its supply voltage reduced.
The theoretical explanation above is rather sketchy, but we did not feel it necessary to have a more careful calculation of the dynamic relations.
We were satisfied with finding, by tests with models (regardless of the explan-ation one wishes to give to the phenomena) that the inventive effect is achieved if one proceeds as specified in the accompanying claims.
The advantages of the invention are apparent. In both a feeder anda sieve, the transport speed can be varied as needed. It is also possible to compensate for uneven load.
- ~a B
sy optimizing the throw angle it is also possible to obtain an improved screening effect and control the screening so that the screen meets the material, when falling down, in such a way that the material and the screen have opposite movements, thus achieving the best sorting effect and avoiding plugging.
Claims (2)
1. Method for regulating the throw angle of a vibrating device such as a sieve or feeder of the type which has a drive means with out-of-balance means around two shafts which are parallel to each other, characterized in that the two out-of-balance means are of different dimensions, are driven by individual motors and have their shafts arranged in relation to the center of gravity of the device in such a way that the center of gravity lies on an Apollonios' circle to the two shafts, so determined that the ratio of the distances from the center of gravity to the axes of rotation is inversely proportional to the products of the out-of-balance weights of the respective out-of-balance means and their mean distance to the respective axis of rotation, the throw angle being affected by changing the power of one of he motors in relation to that of the other.
2. Method according to Claim 1, characterized in that the change in the relation between the powers of the motors is achieved by supplying one of the two motors, which are of the short-circuit asynchronic type, with a lower excitation voltage.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE7809573-4 | 1978-09-12 | ||
| SE7809573A SE445090B (en) | 1978-09-12 | 1978-09-12 | SETTING TO ADJUST THE TURN ANGLE BY A VIBRATING DEVICE |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1139267A true CA1139267A (en) | 1983-01-11 |
Family
ID=20335800
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000334865A Expired CA1139267A (en) | 1978-09-12 | 1979-08-31 | Method for regulating the throw angle of a vibrating sieve or feeder |
Country Status (10)
| Country | Link |
|---|---|
| AT (1) | AT375282B (en) |
| CA (1) | CA1139267A (en) |
| DE (1) | DE2936541A1 (en) |
| DK (1) | DK379279A (en) |
| FI (1) | FI792816A (en) |
| FR (1) | FR2435972A1 (en) |
| GB (1) | GB2034437B (en) |
| NL (1) | NL7906712A (en) |
| NO (1) | NO150226C (en) |
| SE (1) | SE445090B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104889057A (en) * | 2015-06-23 | 2015-09-09 | 安徽理工大学 | Three-degree-of-freedom flip-flow screen |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5014564A (en) * | 1990-03-27 | 1991-05-14 | Calvest Associates | Eccentric drive mechanism |
| GB9210624D0 (en) * | 1992-05-19 | 1992-07-01 | Alfa Laval Separation Ab | Vibratory screening apparatus |
| US5896998A (en) * | 1992-05-19 | 1999-04-27 | Alfa Laval Separation Ab | Vibratory screening apparatus |
| DE69709146T2 (en) * | 1996-10-15 | 2002-07-04 | Rig Technology Ltd., Aberdeen | IMPROVED VIBRATION SCREENER |
| US6679385B2 (en) * | 2001-04-18 | 2004-01-20 | M I Llc. | Motor control system for vibrating screen separator |
| AU2015263837B2 (en) * | 2014-05-21 | 2018-05-10 | Sandvik Rock Processing Australia Pty Limited | Modular exciter beam |
| GB2573535B (en) | 2018-05-08 | 2021-05-05 | Terex Gb Ltd | Adjustable vibratory drive system |
| ES2928081T3 (en) * | 2020-06-28 | 2022-11-15 | Vibra Maschf Schultheis Gmbh & Co | Heavy-duty vortex channel device for treating plastic granules and related processes |
| BR102020018291A2 (en) * | 2020-09-08 | 2021-04-06 | Haver & Boecker Latinoamericana Máquinas Ltda | SYSTEM, EQUIPMENT AND MONITORING PROCEDURE, PREDICTIVE MAINTENANCE AND OPERATIONAL OPTIMIZATION OF VIBRATORY SIEVES |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1098287A (en) * | 1964-12-12 | 1968-01-10 | Mueller Ludwig | Vibratory mechanism |
| SE324493B (en) * | 1965-05-21 | 1970-06-01 | Schenk C Maschinenfabrik Gmbh |
-
1978
- 1978-09-12 SE SE7809573A patent/SE445090B/en not_active IP Right Cessation
-
1979
- 1979-08-31 CA CA000334865A patent/CA1139267A/en not_active Expired
- 1979-09-07 FR FR7922436A patent/FR2435972A1/en active Granted
- 1979-09-07 NL NL7906712A patent/NL7906712A/en not_active Application Discontinuation
- 1979-09-10 DE DE19792936541 patent/DE2936541A1/en not_active Withdrawn
- 1979-09-10 NO NO792924A patent/NO150226C/en unknown
- 1979-09-11 GB GB7931440A patent/GB2034437B/en not_active Expired
- 1979-09-11 DK DK379279A patent/DK379279A/en not_active Application Discontinuation
- 1979-09-11 FI FI792816A patent/FI792816A/en not_active Application Discontinuation
- 1979-09-11 AT AT0598379A patent/AT375282B/en active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104889057A (en) * | 2015-06-23 | 2015-09-09 | 安徽理工大学 | Three-degree-of-freedom flip-flow screen |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2435972B1 (en) | 1983-11-25 |
| DE2936541A1 (en) | 1980-03-20 |
| FR2435972A1 (en) | 1980-04-11 |
| SE445090B (en) | 1986-06-02 |
| SE7809573L (en) | 1980-03-13 |
| NO150226C (en) | 1984-09-12 |
| DK379279A (en) | 1980-03-13 |
| AT375282B (en) | 1984-07-25 |
| ATA598379A (en) | 1983-12-15 |
| NO150226B (en) | 1984-06-04 |
| FI792816A (en) | 1980-03-13 |
| NO792924L (en) | 1980-03-13 |
| GB2034437A (en) | 1980-06-04 |
| GB2034437B (en) | 1982-08-04 |
| NL7906712A (en) | 1980-03-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |