WO2010092473A1

WO2010092473A1 - Conveyor system of trays or similar

Info

Publication number: WO2010092473A1
Application number: PCT/IB2010/000285
Authority: WO
Inventors: Giacomo Guidi; Gabriele Mazzotti; Tonino Ferri
Original assignee: Sacmi Cooperativa Meccanici Imola Società Cooperativa
Priority date: 2009-02-16
Filing date: 2010-02-15
Publication date: 2010-08-19
Also published as: EP2396259A1; WO2010092473A8; ITBO20090080A1; IT1398600B1

Abstract

A conveyor system (1) for conveying objects has at least one rail (2) having a top wall (9) and extending along a path; a number of electromagnets (19) housed inside the rail (2); control means for sequentially operating the electromagnets (19); and at least one support (4) for supporting the objects, and which is movable on the rail (2) to transport the objects, has a bottom wall (7), and has at least one permanent magnet (13) inside; the permanent magnet (13), in use, is designed to interact with the electromagnets (19) in the rail (2) to move the support (4) on said rail (2); and the support (4) is connected to the rail (2) so that the bottom wall (7) of the support (4) rests on and, in use, slides on the top wall (9) of the rail (2).

Description

CONVEYOR SYSTEM FOR TRAYS OR SIMILAR

TECHNICAL FIELD

The present invention relates to a conveyor system for trays or similar.

More specifically, the present invention relates to a conveyor system for conveying trays or pallets of objects - e.g. chocolates or sweets in the food industry, or tablets in the pharmaceutical industry - from a first to a second station of a processing line for processing the objects. The conveyor system comprises at least one rail, along which the trays, comprising a number of seats for the objects, are conveyed . BACKGROUND ART

Many known conveyor systems employ endless conveyor belts made of rubber or steel and normally driven by two motor-driven pulleys. The trays to be conveyed between two stations are placed on the outer surface of the conveyor belt, and, as they travel between the two stations, may be held in place and prevented from slipping crosswise to the conveyor belt by external sidewalls or sheet metal plates.

In addition to conveyor belts, other widely differing conveyor systems are also commonly used, and which are normally chosen according to the type of product to be conveyed or, for example, the location of the conveyor system. Among the most commonly used are chain conveyors, which comprise at least two side by side parallel chains, on which the trays travel; roller conveyors (or so-called roller beds) comprising a number of side by side powered rollers; and bucket conveyors, which are mainly used for vertically lifting and conveying objects in bulk.

In all the above conveyor systems, power is transmitted from a motor to a pulley, and from this to the conveyor belt or chains by a drive chain or belt or a cascade system of gears. Whichever the case, the presence in the conveyor system of moving components connected mechanically to fixed components calls for lubrication, to reduce friction and wear of the components, and therefore frequent maintenance and cleaning of the components. If not accompanied by adequate cleaning procedures, the use of lubricants may result in contamination of the objects.

US5373992 describes a movable body and a conveyor device. In actual use, the movable body moves along the path of the conveyor device on ball bearings housed inside grooves (column 3, lines 58-61, and Figure 5) and located between the movable body and the device to keep them apart.

DE3402143 and GB2133755 each describe a movable body and a conveyor device. In actual use, the movable body floats over a rail on a cushion of air from holes in the rail (Figure 2 in DE3402143; and lines 4-8 of the abstract, and Figure 3 in GB2133757) . The devices described in US5373992, DE3402143 and GB2133757 are relatively complicated, and comprise various components requiring frequent maintenance and/or cleaning. US5309049 describes a movable body and a conveyor device. In actual use, the movable body is raised and floated by an electromagnetic system (lines 1-5 of the abstract) .

Besides being extremely expensive in itself, the device described in US5309049 is also extremely expensive to run, and calls for relatively frequent cleaning and maintenance.

The need for a clean conveyor system (i.e. involving minimum use of lubricants) is particularly felt in industries, such as the food and pharmaceutical industries, governed by strict regulations concerning, for example, cleaning and protection of electric and electronic processing line components. DISCLOSURE OF INVENTION It is an object of the present invention to provide a conveyor system for trays or similar, which is cheap and easy to produce, is designed to eliminate at least some of the drawbacks of the known art, and, in particular, provides for a clean workplace, and involves relatively little maintenance (and/or cleaning) .

According to the present invention, there is provided a conveyor system for trays or similar, as claimed in the accompanying Claims . BRIEF DESCRIPTION OF THE DRAWINGS

A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows a schematic view in perspective of a preferred embodiment of the conveyor system according to the present invention;

Figure 2 shows a detail of Figure 1, with parts removed for clarity; Figure 3 shows a section of the Figure 2 detail;

Figure 4 shows an exploded view of the Figure 2 detail;

Figure 5 shows a side view, with parts removed for clarity, of the Figure 1 conveyor system. BEST MODE FOR CARRYING OUT THE INVENTION

Number 1 in Figure 1 indicates as a whole a conveyor system for conveying objects - such as chocolates in the food industry, or tablets in the pharmaceutical industry - along a path from a first to a second station (not shown) of a line (not shown) for processing the objects.

More specifically, conveyor system 1 comprises two parallel rails 2 spaced apart, extending between the first and second station (not shown) , and for conveying the objects. Each rail 2 comprises a number of base modules 3, which are parallelepiped-shaped in cross section and arranged successively end to end, as shown more clearly in Figure 5. The modular design of rails 2 enables conveyor system 1 to be adapted fairly easily to the path, and also enables connection of two stations (not shown) located far apart along the object processing line. Rails 2 support a number of parallelepiped-shaped trays 4, the top surface 5 of each of which has a number of seats 6 for housing the objects for processing. Each tray 4 is made of plastic material, and has a bottom wall 7, the two end portions 8 of which each rest on a top wall 9 of a respective rail 2. Bottom wall 7 is substantially flat, i.e. has a substantially flat surface facing wall 9; and top wall 9 is also substantially flat, i.e. has a substantially flat surface facing bottom wall 7. In the embodiment shown, walls 7 and 9, i.e. the respective said facing surfaces, are substantially horizontal.

As shown in Figure 1, each tray 4 is approximately as wide as the distance between the two rails 2. That is, the lateral surfaces 10 of each tray 4 are flush with respective outer surfaces 11 of respective rails 2, so that conveyor system 1 as a whole has a fairly straightforward gantry- or inverted-U-shaped cross section.

As shown more clearly in Figures 2 and 3 , each tray 4 has two parallel rows 12 of permanent magnets 13 embedded in tray 4, at the two end portions 8 of bottom wall 7, so as to form an alternating N/S polarity. At a preliminary stage in the manufacture of trays 4 using a known plastics molding technique, permanent magnets 13 can be integrated directly inside the mold of tray 4, so as to obtain tray 4, with permanent magnets 13 integrated inside it, in one step. As shown in Figures 3 and 4, each base module 3 comprises a substantially parallelepiped-shaped, hollow outer cover 14 made of aluminium or plastic material, e.g. nylon. The hollow interior of outer cover 14 is divided into two cavities 16 and 17 by a partition wall 15 parallel to top wall 9; and the top cavity 16 is larger than the bottom cavity 17, which serves to fasten and possibly cool base module 3, as described below.

Top cavity 16 houses a thin, rectangular cross- section bar 18 of ferromagnetic material, e.g. mild steel ClO, to which a number of electromagnets 19 are connected at a preliminary stage in the assembly of base module 3. Each electromagnet 19, as is known, comprises a core of ferromagnetic material, about which is wound a solenoid, i.e. a coil of numerous turns of electric wire, to generate a magnetic field when electric current is fed through the coil.

Top cavity 16 also houses a layer 20 of insulating material, which is substantially the same width but no wider than the inside width of top cavity 16. Layer 20 of insulating material has a top surface 21 shaped to form a seat 22, which houses bar 18 of ferromagnetic material, so as to form a barrier between bar 18 of ferromagnetic material and a printed circuit board (PCB) 23 interposed between and contacting a top surface of partition wall 15 and a bottom surface 24 of layer 20 of insulating material .

Layer 20 of insulating material serves to separate bar 18 of ferromagnetic material from printed circuit board 23, which in turn serves to electrically connect electromagnets 19 and, at the same time, acts as a mechanical support for the components inside top cavity 16. Alternatively, as opposed to inserting printed circuit board 23 inside top cavity 16, the pins of electromagnets 19 of each base module 3 may be connected electrically by hard copper wiring.

To induce current flow through the coils, electromagnets 19 are operated by control means, and in particular by a linear stepper motor (not shown) , which is a widely used type of electric motor, by employing no position or speed sensors. In this case, too, the linear stepper motor is open-loop operated, i.e. with no feedback control of the motor. In addition, this type of motor provides for operating electromagnets 19 in groups .

The electromagnets 19 of each base module 3 are typically connected partly in series and partly in parallel, so the electric load is adequate to the voltage of the linear stepper motor, which controls the electromagnets 19 of each base module 3 simultaneously to change the orientation of each electromagnet 19. Interaction of electromagnets 19 with permanent magnets 13 in tray 4 moves tray 4 on rails 2. That is, current flow through the coils of electromagnets 19, and the change in orientation of electromagnet 19 generate a variable magnetic field that attracts the movable part of conveyor system 1, i.e. the permanent magnets 13 in tray 4.

Since no mechanical connections are involved, tray 4 moves on rails 2 by bottom wall 7 of tray 4 simply sliding on top wall 9 of each rail 2. It should be pointed out that wall 7 slides in contact with wall 9. In other words, the weight of a supporting member (tray) 4 is transferred directly (with no other members, e.g. bearings, in between) from wall 7 to wall 9.

The fact that walls 7 and 9 contact one another (i.e. with no other members or a gap in between), means relatively little cleaning and/or maintenance is required (as compared with the known devices referred to) .

Travelling speed is a free parameter that is regulated by the linear stepper motor controlling and regulating electromagnets 19. Which means trays 4 can be fed continuously or in any other mode on rails 2.

Two connectors (not shown) are connected to the ends of each base module 3 to connect it to the adjacent upstream and downstream base modules 3 forming rail 2. When, in use, the base module 3 is connected directly by the connectors (not shown) to the linear stepper motor, the connectors supply the necessary electric current to electromagnets 19.

One example of how the electromagnets are connected and operated is described in "Linear Electric Actuators

Sc Generators", I. Boldea & Syed A. Nasar; Cambridge University Press, 2005; which is fully included herein by way of reference.

In some embodiments, conveyor system 1 comprises a number of linear stepper motors, each connected to and for controlling a specific number of base modules 3. Conveyor system 1 also comprises a known control unit (not shown) connected electrically to and for controlling the linear stepper motor/s, and which typically comprises a user interface (e.g. comprising a screen and/or keyboard) . Bottom cavity 17 is bounded at the top, as stated, by partition wall 15, and at the bottom by a bottom wall 25 of rail 2, as shown more clearly in Figure 3. Two walls 26, perpendicular to partition wall 15 and bottom wall 25, divide the inside of bottom cavity 17 into three conduits. Of these, the two end conduits 27 and 28 have substantially the same rectangular cross section, and are closed on all four sides,- while the centre conduit 29 has an opening 31 in bottom wall 25. Bottom wall 25 comprises two appendixes 30, which define the bottom of centre conduit 29, are spaced apart to define the bottom opening 31, and are used to fix base module 3, by means of appropriate fastening systems (not shown) , to a supporting structure (not shown) . The two end conduits 27, 28, on the other hand, are used for conditioning rail 2 by inserting appropriate material to keep the heat generated by the components of rail 2 below an acceptable threshold level, and so ensure correct operation of the components .

An important point to note is that bottom wall 7 and top wall 9 advantageously contact each other by respective substantially smooth surfaces. This enables bottom wall 7 to slide smoothly on top wall 9. To reduce wear caused by bottom wall 7 of tray 4 sliding on top wall 9 of rail 2, a layer of coating material (not shown) , in particular a TEFLON® coating, may be applied to top wall 9.

Control, as stated, being open-loop, a number of position sensors (not shown) may be installed off conveyor system 1 but integrated, for example, in the object processing line machinery, to determine the presence of trays 4 at each processing station. External sensors are especially recommended to ensure trays 4 move into the desired position at stations performing delicate operations, such as filling seats 6 of trays 4. In a further embodiment not shown in the drawings , conveyor system 1 comprises two rails 2 as described above, and on which run trolleys (not shown) , each supporting a respective tray 4. Trays 4 are parallelepiped-shaped, are made of plastic material, and each have a top surface 5, in which are formed a number of seats 6 for housing the objects for processing; and a bottom surface 7, the two end portions 8 of which cooperate with the respective trolley (not shown) . Each trolley (not shown) is of a width substantially equal to the width of trays 4 and the distance between the two rails 2, and has two parallel rows 12 of permanent magnets 13 embedded in the trolley (not shown) to form an alternating N/S polarity. The interaction of electromagnets 19 in rails 2 and permanent magnets 13 in the trolleys (not shown) moves the trolleys (not shown) , fitted integrally with trays 4, along rails 2.

At a preliminary stage in the manufacture of the trolleys using a known plastics molding technique, permanent magnets 13 can be integrated directly inside the trolley mold, so as to obtain the trolley, with permanent magnets 13 integrated inside it, in one step. This embodiment permits considerable cost-saving, by enabling existing trays 4, if still usable, to be simply fitted to trolleys with integrated permanent magnets 13, as opposed to providing a whole new stock of trays 4 or pallets.

In another embodiment not shown in the drawings, conveyor system 1 comprises one rail 2 of the type described above. Current flow through the coils of electromagnets 19, and the change in orientation of each electromagnet 19 generates a variable magnetic field that attracts the movable part of conveyor system 1, i.e. the permanent magnets 13 in tray 4, and at the same time produces a self-righting effect. In the event of interference factors affecting the desired position of tray 4 with respect to rail 2, such as a bend in the path between one station and the next, the self-righting effect tends to restore tray 4 to the right position, even without the aid of mechanical constraints for keeping the tray in position as it travels from one station to the next.

In other embodiments not shown, bottom wall 7 and top wall 9 are complementary and non-flat in shape, i.e. may be other shapes, e.g. V-shaped, as opposed to flat, as shown in the drawings .

In some embodiments, top wall 9 has a surface

(facing wall 7) with substantially no recesses.

Advantageously, top wall 9 has substantially no holes. In other words, top wall 9 has a substantially smooth surface (facing wall 7) .

In some embodiments, bottom wall 7 has a surface

(facing wall 9) with substantially no recesses, and advantageously has substantially no holes. In other words, bottom wall 7 has a substantially smooth surface

(facing wall 9) .

The fact that wall 7 and/or wall 9 have no recesses or holes means relatively little cleaning and/or maintenance is required (as compared with the known devices referred to) ; and the actual cleaning required is relatively simple.

Conveyor system 1 according to the present invention has numerous advantages over the state of the art .

In particular, conveyor system 1 provides for conveying trays 4 individually, so the distance between adjacent trays 4 can be increased or decreased. Trays 4 are conveyed with no need for motion transmission means, such as drive chains or belts or cascade gear systems, but simply by bottom wall 7 sliding on top wall 9 of each rails 2. As a result, lubricant use and potential damage to mechanical parts are minimized.

Advantageously, in the case of flat walls 7 and 9, movement is in no way dependent on mechanical guide members of any sort, which means cleaning is even more straightforward and faster. The fact that conveyor system 1 has no underside recesses, grooves, or bends of any sort makes for an extremely clean structure as a whole, requiring no lubricants, and in which electric and electronic devices are protected inside rails 2 or trays 4. Conveyor system 1 as described above provides for very high output levels, by simply increasing the number of trays 4 circulating through it. Moreover, the travelling speed of trays 4 is controllable by simply adjusting the control strategy of the linear stepper motor, with no intervention required on conveyor system 1. And finally, as stated, the modular design of rails 2 enables connection of even widely separated object processing stations. Though conveyor system 1 in any of the various embodiments described is independent of the type of object conveyed, it is obviously especially suitable for, but in no way limited to, industries, such as the food or pharmaceutical industry, governed by strict regulations concerning cleaning and protection of electric and electronic components .

Claims

1) A conveyor system (1) for conveying objects, and comprising : at least one rail (2) having a top wall (9) and extending along a path; a number of electromagnets (19) housed inside the rail (2); control means for sequentially operating the electromagnets (19); and at least one support (4) for supporting the objects, and which is movable on the rail (2) to transport the objects, has a bottom wall (7) , and comprises at least one permanent magnet (13) inside; the permanent magnet (13), in use, being designed to interact with the electromagnets (19) in the rail (2) to move the support (4) on said rail (2); the conveyor system being characterized in that the support (4) is connected to the rail (2) so that the bottom wall (7) of the support (4) rests on and, in use, slides on and in contact with the top wall (9) of the rail (2).

2) A conveyor system as claimed in Claim 1, wherein said bottom wall (7) and said top wall (9) are substantially complementary in shape.

3) A conveyor system as claimed in Claim 1 or 2 , wherein said bottom wall (7) and said top wall (9) are substantially flat. 4) A conveyor system as claimed in one of the foregoing Claims, wherein said bottom wall (7) and said top wall (9) have substantially no recesses and/or holes . 5) A conveyor system as claimed in one of the foregoing Claims, wherein said bottom wall (7) and said top wall (9) are substantially horizontal.

6) A conveyor system as claimed in one of the foregoing Claims, wherein the control means for sequentially operating the electromagnets (19) comprise at least a linear stepper motor.

7) A conveyor system as claimed in one of the foregoing Claims, wherein the control means are designed to simultaneously operate groups of electromagnets (19). 8) A conveyor system as claimed in one of the foregoing Claims, wherein the rail (2) comprises a number of identical base modules (3) connected to one another along the path; each base module (3) housing a number of electromagnets (19) . 9) A conveyor system as claimed in Claim 8, wherein the control means simultaneously operate all the electromagnets (19) housed in a base module (3) .

10) A conveyor system as claimed in one of the foregoing Claims, wherein the support (4) comprises a parallelepiped-shaped tray (4), in the top surface (5) of which are formed a number of seats (6) for housing the objects, and which has a number of permanent magnets (13) embedded in it. 11) A conveyor system as claimed in one of Claims 1 to 9, wherein the support (4) comprises a parallelepiped-shaped tray (4) , in the top surface (5) of which are formed a number of seats (6) for housing the objects; and a trolley, which has a number of permanent magnets (13) embedded in it, and supports a respective tray (4) .

12) A conveyor system as claimed in Claim 10 or 11, wherein the support (4) comprises two rows (12) of permanent magnets (13) located at the two end portions (8) of the bottom wall (7) of the support (4) .

13) A conveyor system as claimed in one of the foregoing Claims, wherein the conveyor system (1) comprises two parallel rails (2) spaced apart, and each of which is designed, in use, to interact with a respective row (12) of permanent magnets (13) in the support (4) .

14) A conveyor system as claimed in Claim 13, wherein each support (4) is approximately as wide as the distance between the rails (2), so as to define, together with the rails (2), a gantry- or inverted-U- shaped structure.

15) A conveyor system as claimed in one of the foregoing Claims, wherein the rail (2) is substantially parallelepiped-shaped, and comprises a hollow outer cover (14) housing the electromagnets (19) .

16) A conveyor system as claimed in Claim 15, wherein the rail (2) comprises a bar (18) of ferromagnetic material connected to the electromagnets (19) and housed inside the outer cover (14) .

17) A conveyor system as claimed in Claim 16, wherein the rail (2) comprises a printed circuit board (23) housed in the outer cover (14); and a layer (20) of insulating material housed in the outer cover (14) and interposed between the bar (18) of ferromagnetic material and the printed circuit board (23) .

18) A conveyor system as claimed in one of the foregoing Claims, wherein the rail (2) comprises at least one conditioning conduit (27, 28) inside the rail (2) .