ELECTROMAGNETIC CONVEYOR SYSTEM
A conveyor system for conveying electrically conductive articles such as aluminum cans. The conveyor system comprises a plurality of coils below the top surface of an electromagnetic conveyor at a junction between an infeed conveyor and a discharge conveyor. The coils propagate electromagnetic flux waves that induce currents in the electrically conductive articles that force the articles to follow a conveying path from the infeed to the discharge conveyor. Dead spots on the electromagnetic conveyor can be eliminated by adjusting the coil drive waveforms.
The invention relates generally to power-driven conveyors and more particularly to conveyors conveying electrically conductive articles, such as cans, electromagnetically.
Conveyors are used to transport articles through manufacturing processes. The transport of empty aluminum beverage cans can be difficult in transitions where the cans are transferred from one conveyor to another. The lightweight cans are prone to tipping at the transitions and to stranding on transfer dead plates. Manual intervention is required to deal with toppled and stranded cans. But manual intervention increases manufacturing costs and risks contamination of the cans. And if not dealt with, the stranding of cans can result in the costly mixing of can batches.
SUMMARYOne version of a conveyor system embodying features of the invention comprises a first conveyor conveying electrically conductive articles in a first direction to an exit end, a second conveyor conveying the electrically conductive articles from an entrance end in a second direction different from the first direction, and a diverter forming a junction between the exit end of the first conveyor and the entrance end of the second conveyor The diverter includes an entrance adjacent to the exit end of the first conveyor receiving the electrically conductive articles on a top surface from the exit end of the first conveyor and an exit adjacent to the entrance end of the second conveyor. Coils are arranged in a matrix of contiguous first and second zones below the top surface. The coils in each of the first zones produce an electromagnetic flux wave that forces the electrically conductive articles on the top surface above the zone to move in the first direction. The coils in each of the second zones produce an electromagnetic flux wave that forces the electrically conductive articles on the top surface above the zone to move in the second direction. At least some of the zones along the entrance are first zones and at least some of the zones along the exit are second zones. The electrically conductive articles are directed from the entrance to the exit by the coils in the first and second zones and onto the second conveyor.
Another version of a conveyor system embodying features of the invention comprises a first conveyor conveying electrically conductive articles in a first direction to an exit end and a second conveyor conveying the electrically conductive articles from an entrance end in a second direction. The angle θ between the first direction and the second direction is given by 0°<θ≤90°. A diverter forms a junction between the exit end of the first conveyor and the entrance end of the second conveyor. The diverter includes an entrance adjacent to the exit end of the first conveyor receiving the electrically conductive articles on a top surface from the exit end of the first conveyor and an exit adjacent to the entrance end of the second conveyor. Coils arranged in parallel below the top surface produce an electromagnetic flux wave that forces the electrically conductive articles on the top surface above the coils to move in a third direction. The angle a between the first direction and the third direction is given by 0°<α<θ. The electrically conductive articles are directed from the entrance to the exit by the coils and onto the second conveyor.
Yet another version of a conveyor system embodying features of the invention comprises a first conveyor conveying electrically conductive articles in a first direction to an exit end, a second conveyor conveying the electrically conductive articles from an entrance end in a second direction different from the first direction, and a diverter forming a junction between the exit end of the first conveyor and the entrance end of the second conveyor. The diverter includes an entrance adjacent to the exit end of the first conveyor receiving the electrically conductive articles on a top surface from the exit end of the first conveyor and an exit adjacent to the entrance end of the second conveyor. Coils are arranged in an arc below the top surface from the entrance to the exit. In a plan view perpendicular to the top surface, each of the coils has a narrow end at the inside of the arc and an opposite wider end at the outside of the arc. The electrically conductive articles are directed from the entrance to the exit by the coils and onto the second conveyor.
Another version of a conveyor system embodying features of the invention comprises an electromagnetic conveyor that includes an entrance over which electrically conductive articles are transferred onto a top surface and an exit over which electrically conductive articles are transferred off the top surface. Coils are arranged below the top surface in an array and produce electromagnetic flux waves causing forces that move the electrically conductive articles across the top surface from the entrance to the exit. A controller drives the coils with drive waveforms characterized by periodic pulses that periodically increase the forces acting on the electrically conductive articles in low-force regions on the top surface to enhance movement of the electrically conductive articles.
Still another version of a conveyor system embodying features of the invention comprises an electromagnetic conveyor that includes a top surface, an entrance over which electrically conductive articles are transferred onto the top surface, an exit over which electrically conductive articles are transferred off the top surface, and a plurality of coils arranged below the top surface in individual zones. The coils produce electromagnetic flux waves causing forces that move the electrically conductive articles through the zones across the top surface from the entrance to the exit. Controllers associated with the zones drive the coils with drive waveforms having different frequencies or phase angles in adjacent zones to enhance movement of the electrically conductive articles.
A conveyor system embodying features of the invention is shown in
As
Although the first and second zones 40, 41 in the diverter 30 can be of different lengths as in
In this example the matrix of contiguous first and second zones 40, 41 is a square matrix of the identical coil modules 42, 42′ arranged in four rows R1-R4 and four columns C1-C4. The rows R1-R4 are aligned in the second conveying direction 29 and perpendicular to the first conveying direction 28, and the columns C1-C4 are aligned in the first conveying direction and perpendicular to the second conveying direction. Furthermore, in this example, there are eleven second coil modules 42′ forcing cans in the second direction 29 toward the exit 33 of the diverter 30 and five coil modules 42 forcing cans in the first direction 28 away from the entrance 32. The coil module 42′ in the row R1 closest to the entrance 32 and the column C4 closest to the exit 33 is in a second zone 41. And all the coil modules 42′ in the column C4 closest to the exit 33 are in second zones 41. Three of the four coil modules in the row R1 closest to the entrance 32 of the diverter 30 are in first zones 40.
In this particular arrangement of coil modules 42, 42′ and zones 40, 41, the number of coil modules in contiguous first zones 40 decreases monotonically row by row away from the entrance 32. (The row R1 closest to the entrance 32 has three coil modules 42 in first zones 40; the next row R2 has two; and the third and fourth rows R3, R4 have none.) Cans fed onto the left side of the diverter 30 at the entrance 32 are pushed in the first zones 40 in the leftmost columns C1, C2 toward the second zones 41 in the far rows R3, R4. Cans immediately to the right of those are pushed in the first zone 40 on the entrance row R1 and the third column C3 to the second zone 41 in the second row R2. Cans fed onto the diverter 30 along its right side 45 and received in the second zone 41 are pushed immediately toward the exit 33. In this way cans closer to the right side 45 of the diverter 30 make a sharper turn to the right than those cans closer to the left side to help maintain the width of the mass of cans.
Of course, other arrangements of the zones and coil modules are possible. For example, the coil module in the first row R1 and the fourth column C4 could be in a first zone to help induce cans onto the diverter 30 before their direction is changed. As another example, the matrix of zones could be arranged as a non-square rectangular array of coil modules. Or each zone could be made of a single coil module whose length defines the length of the zone. And the number of zones and coil modules could be greater or less than shown in
Another version of an electromagnetic diverter for electrically conductive articles is shown in
Yet another version of an electromagnetic diverter is shown in
In
Another alternative coil 80 is shown in
As shown in
A controller for driving the coils in all the examples is shown in
A programmable processor 106 connected to the controller 100, can be connected to other such controllers to coordinate control of all the coil zones. Or the processor 106 could be integrated into each controller 100 instead. A vision system 108 including one or more cameras capturing digital images of the cans 26 in the zones on the conveyor 20 sends the captured images to the processor 106. From the images the processor 106 can detect stranded cans and flow problems and alter the normal coil drive sequence to remedy any problems. For example, one way that dead spots on a diverter or an in-line conveyor can be eliminated is by driving the coils with a waveform as shown in
Another way of eliminating dead spots is by driving the coils in adjacent zones with phase-shifted waveforms as shown in
Yet another way that dead spots can be eliminated is by operating coils in adjacent zones at different frequencies. For example, the coils in one zone could be driven by an 1100 Hz waveform and those in an adjacent zone by an 1102 Hz waveform. Like driving the coils in adjacent zones with a phase shift, driving the coils at different frequencies produces a force acting on the cans in a direction perpendicular to the conveying direction. The frequency difference can be fixed or can be imposed by the processor 106 when stranded cans are detected by the vision system 108.
All the dead-spot-clearing techniques are usable with electromagnetic diverters or with in-line or diverting electromagnetic conveyors to ensure the efficient conveyance of cans from the infeed conveyor to the discharge conveyor.
Aluminum cans were used throughout the description as exemplary electrically conductive conveyed articles. But other electrically conductive articles containing electrically conductive material, such as aluminum or copper, could be conveyed by the coils described.
Claims
1. A conveyor system comprising:
- a first conveyor conveying electrically conductive articles in a first direction to an exit end;
- a second conveyor conveying the electrically conductive articles from an entrance end in a second direction different from the first direction;
- a diverter forming a junction between the exit end of the first conveyor and the entrance end of the second conveyor;
- wherein the diverter includes: a top surface; an entrance adjacent to the exit end of the first conveyor receiving the electrically conductive articles on the top surface from the exit end of the first conveyor; an exit adjacent to the entrance end of the second conveyor; a plurality of coils arranged in a matrix of contiguous first and second zones below the top surface, wherein the coils in each of the first zones produce an electromagnetic flux wave that travels in the first direction and forces the electrically conductive articles on the top surface above the zone to move in the first direction and the coils in each of the second zones produce an electromagnetic flux wave that travels in the second direction and forces the electrically conductive articles on the top surface above the zone to move in the second direction, wherein at least some of the zones along the entrance are first zones and at least some of the zones along the exit are second zones; wherein some of the coils in the diverter are in the first zones and the rest of the coils are in the second zones; wherein the electrically conductive articles are directed from the entrance to the exit by the coils in the first and second zones and onto the second conveyor.
2. (canceled)
3. A conveyor system as in claim 1 wherein the second direction is perpendicular to the first direction.
4. A conveyor system as in claim 1 wherein the coils in each of the zones are staggered along parallel lines oblique to the first and second directions.
5. A conveyor system as in claim 1 wherein each of the first and second zones includes a single coil module having a single iron core along which all the coils in the zone are wound.
6. A conveyor system as in claim 1 wherein each of the first and second zones includes one or more coil modules, each having the same number of coils.
7. A conveyor system as in claim 6 wherein each of the coil modules includes an iron core around which the coils are formed and wherein the iron core in at least some of the coil modules has a stepped structure along at least one end that mates with the stepped structure on the iron core of an adjacent coil module in the same zone.
8. A conveyor system as in claim 6 wherein the coils in the adjacent coil modules of different first zones or different second zones overlap each other.
9. A conveyor system as in claim 6 wherein the matrix of contiguous first and second zones is a rectangular matrix of the coil modules.
10. A conveyor system as in claim 6 wherein the matrix of contiguous first and second zones defines rows of coil modules aligned in the second direction and columns of coil modules aligned in the first direction.
11. A conveyor system as in claim 10 wherein the number of coil modules in contiguous first zones decreases monotonically row by row away from the entrance.
12. A conveyor system as in claim 1 wherein the coils are rectangular with two short sides and two long sides and have a magnetic axis parallel to the top surface and are orthocyclically wound with a crossover region along one of the sides.
13. A conveyor system as in claim 12 wherein the crossover region is along the long side farther from the top surface of the diverter.
14. A conveyor system as in claim 1 comprising a multiphase controller driving the coils in each of the first and second zones.
15. A conveyor system comprising:
- a first conveyor conveying electrically conductive articles in a first direction to an exit end;
- a second conveyor conveying the electrically conductive articles from an entrance end in a second direction, wherein the angle θ between the first direction and the second direction is given by 0°<θ≤90°;
- a diverter forming a junction between the exit end of the first conveyor and the entrance end of the second conveyor;
- wherein the diverter includes: a top surface; an entrance adjacent to the exit end of the first conveyor receiving the electrically conductive articles on the top surface from the exit end of the first conveyor; an exit adjacent to the entrance end of the second conveyor; a plurality of coils arranged in parallel below the top surface and having magnetic axes in a third direction oblique to the first direction and producing an electromagnetic flux wave that forces the electrically conductive articles on the top surface above the coils to move in the third direction, wherein the angle a between the first direction and the third direction is given by 0°<α<θ;
- wherein the electrically conductive articles are directed from the entrance to the exit by the coils and onto the second conveyor.
16. A conveyor system as in claim 15 wherein θ=90°.
17. A conveyor system as in claim 15 comprising a multiphase controller driving the coils.
18. A conveyor system comprising:
- a first conveyor conveying electrically conductive articles in a first direction to an exit end;
- a second conveyor conveying the electrically conductive articles from an entrance end in a second direction different from the first direction;
- a diverter forming a junction between the exit end of the first conveyor and the entrance end of the second conveyor;
- wherein the diverter includes: a top surface; an entrance adjacent to the exit end of the first conveyor receiving the electrically conductive articles on the top surface from the exit end of the first conveyor; an exit adjacent to the entrance end of the second conveyor; a plurality of coils arranged in an arc below the top surface from the entrance to the exit wherein, in a plan view perpendicular to the top surface, each of the coils has a narrow end at the inside of the arc and an opposite wider end at the outside of the arc; wherein the electrically conductive articles are directed from the entrance to the exit by the coils and onto the second conveyor.
19. A conveyor system as in claim 18 wherein the arc subtends an angle of 90°.
20. A conveyor system as in claim 18 wherein the narrow end of the coil is taller than the wider end in a direction perpendicular to the top surface.
21. A conveyor system as in claim 18 comprising an iron core around which the coil is formed and wherein the thickness of the iron core is constant along the length of the coil.
22. A conveyor system as in claim 18 comprising iron cores around which the coils are formed, wherein the thickness of the iron cores increases from the end of the coils at the inside of the arc to the end of the coils at the outside of the arc.
23. A conveyor system as in claim 18 comprising iron cores around which the coils are formed, wherein the ratio of the thickness of the coils to the thickness of the iron cores is a constant along the lengths of the iron cores.
24. A conveyor system as in claim 18 comprising an iron core around which the coil is formed, wherein the thickness of the iron core is constant along its length.
25. A conveyor system as in claim 18 wherein the coils are orthocyclically wound with the crossover region at the end of the coil closer to the inside of the arc.
26. A conveyor system as in claim 18 wherein the arc of coils forms an outer arc and the conveyor system comprises a second plurality of coils arranged in an inner arc inside the outer arc.
27. A conveyor system as in claim 18 comprising a multiphase controller driving the coils.
28. A conveyor system comprising:
- an electromagnetic conveyor including: a top surface; an entrance over which electrically conductive articles are transferred onto the top surface; an exit over which electrically conductive articles are transferred off the top surface; a plurality of coils arranged below the top surface in an array and producing electromagnetic flux waves causing forces that move the electrically conductive articles across the top surface from the entrance to the exit;
- a controller driving the coils with drive waveforms characterized by a first amplitude and periodic pulses of a greater second amplitude that periodically increase the forces acting on the electrically conductive articles in low-force regions on the top surface to enhance movement of the electrically conductive articles from low-force regions on the top surface.
29. A conveyor system as in claim 28 wherein the controller drives the coils with the periodic pulses at a fixed rate.
30. A conveyor system as in claim 28 wherein the periodic pulses are formed by modulating the amplitude of the drive waveforms.
31. A conveyor system as in claim 28 further comprising a capacitor in series with the controller and the coils to form a resonant circuit with the coils with a resonant frequency and wherein the frequency of the drive waveform is close enough to the resonant frequency to ensure that the reactive impedance of the resonant circuit is not dominant.
32. A conveyor system as in claim 28 further comprising:
- a processor; and
- a vision system capturing digital images of the electrically conductive articles being conveyed on the top surface of the electromagnetic conveyor and sending the digital images to the processor;
- wherein the processor directs the controller to drive the coils with the drive waveforms characterized by periodic pulses whenever stopped or slowed articles are detected in the digital images.
33. A conveyor system comprising:
- an electromagnetic conveyor including: a top surface; an entrance over which electrically conductive articles are transferred onto the top surface; an exit over which electrically conductive articles are transferred off the top surface; a plurality of coils arranged below the top surface in individual zones and producing electromagnetic flux waves causing forces that move the electrically conductive articles through the zones across the top surface from the entrance to the exit;
- controllers associated with the zones and driving the coils with drive waveforms having different frequencies or phase angles in adjacent zones to enhance movement of the electrically conductive articles from zone to zone.
34. A conveyor system as in claim 33 wherein the controllers drive the coils with the drive waveforms having fixed different frequencies or fixed phase angles.
35. A conveyor system as in claim 33 further comprising capacitors in series with the controllers and the coils to form resonant circuits with the coils with resonant frequencies and wherein the frequencies of the drive waveforms are close enough to the resonant frequencies to ensure that the reactive impedances of the resonant circuits are not dominant.
36. A conveyor system as in claim 33 further comprising:
- a processor; and
- a vision system capturing digital images of the electrically conductive articles being conveyed on the top surface of the electromagnetic conveyor and sending the digital images to the processor;
- wherein the processor directs the controller to drive the coils with the drive waveforms having different frequencies or phase angles in adjacent zones whenever stopped or slowed articles are detected in the digital images.
Type: Application
Filed: Apr 13, 2018
Publication Date: Oct 17, 2019
Inventors: Aditya Mehendale (Geldrop), Ewout Peter van der Laan (Eindhoven), Funda Sahin-Nomaler (Eindhoven), Pieter Aarnout Klop (Waalre)
Application Number: 15/953,127