WO2007073164A2

WO2007073164A2 - System comprising two conveyor belts adjoining one another at an angle and product carrier for use with said system

Info

Publication number: WO2007073164A2
Application number: PCT/NL2006/000647
Authority: WO
Inventors: Franciscus Johannes Maria Van Zaal; Johannes Adrianus Kok
Original assignee: Frans Van Zaal Totaal Techniek
Priority date: 2005-12-22
Filing date: 2006-12-20
Publication date: 2007-06-28
Also published as: NL1030742C1; WO2007073164A3; EP1968872A2

Abstract

A description is given of a system comprising two conveyor belts adjoining one another at an angle, in which means are present to transfer a product carrier (4) which is movable on a supplying conveyor belt to a removing conveyor belt on account of the friction force which is exerted by both conveyor belts on the product carrier during the transfer, the product carrier being rotated in order to assume the same position relative to the removing conveyor belt as to the supplying conveyor belt, in which the product carrier is rectangular and at least one of its sides has a hollow incision, whereas the means to transfer the product carrier from the first to the removing conveyor belt are selected from: a fixed projection (14) which is disposed near the corner of the angle at which the conveyor belts are to one another and said projection, during at least part of the transfer, is in contact with the side of the product carrier with the hollow incision and guide means (15, 15’’) which are rotatably arranged to move from a position outside one of the conveyor belts to a position where they extend above the surface of a conveyor belt and said guide means are in contact with at least one corner of the product carrier, during at least part of the transfer and a combination of a fixed projection and guide means.

Description

System comprising two conveyor belts adjoining one another at an angle and product carrier for use with said system.

The present invention relates to a system comprising two conveyor belts adjoining one another at an angle, in which means are present to transfer a product carrier which is movable on a supplying conveyor belt to a removing conveyor belt on account of the friction force which is exerted by both conveyor belts on the product carrier during the transfer, the product carrier being rotated in order to assume the same position relative to the removing conveyor belt as to the supplying conveyor belt.

In the context of the present invention, the expression "the same position" as used above is intended to mean that the position which the product carrier assumes relative to the removing conveyor belt is substantially identical to that relative to the supplying conveyor belt; however, small variations may occur and are permissible.

A system of this type is known from US-A-2 526 856. Said publication describes a system comprising two conveyor belts adjoining one another at right angles, in which a product carrier carried on a supplying conveyor belt is transferred to a removing conveyor belt via three auxiliary rollers, disposed between the end of the first belt and the side of the second belt, as well as a roller disposed at the corner of the angle at which the conveyor belts are to one another, the shaft of which is vertical. Of the auxiliary rollers between the end of the first belt and the side of the second belt, one is driven, while the other two can freely rotate. As soon as part of it experiences the friction force of the second belt, a product carrier which is to be transferred is rotated by being detained by means of the vertically disposed roller in the corner and rotation of the driven auxiliary roller in order to assume its position on the second belt.

It is an object of the present invention to improve a system of the type referred to in the preamble and to this end the invention is characterized by the fact that the product carrier is rectangular and at least one of its sides has a hollow incision, whereas the means to transfer the product carrier from the supplying conveyor belt to the removing conveyor belt are selected from:

- a fixed projection which is disposed near the corner of the angle at which the two conveyor belts are to one another and said projection, during at least part of the transfer, is in contact with the side of the product carrier with the hollow incision and

- guide means which are rotatably arranged to move from a position outside one of the conveyor belts to a position where they extend above the surface of a conveyor belt and said guide means are in contact with at least one corner of the product carrier, during at least part of the transfer, and

- a combination of a fixed projection and guide means.

Surprisingly, in one embodiment, it was found that an excellent transfer of a product carrier from a supplying conveyor belt to a removing conveyor belt can be achieved by making a hollow incision on one side of a rectangular product carrier and designing the detaining point, designed as a roller whose shaft is vertical in the abovementioned reference, as a projection arranged in a fixed position. Making a hollow incision on one side of the product carrier, which is in contact with the fixedly arranged projection during at least part of the transfer, offers the possibility for the product carrier to more quickly adopt the speed of the removing conveyor belt, as a result of which the transfer process proceeds more smoothly and quickly.

In another embodiment, the means for transferring a product carrier from a supplying belt to a removing belt consist of rotatably arranged guide means which, in the active position, are turned so as to be above the surface of one of the belts and thus guide the transfer of a product carrier on the supplying belt.

It is also possible to use a combination of a fixedly arranged projection and guide means, which are each positioned in a suitable manner .

Incidentally, where the present invention speaks of a supplying or removing conveyor belt, respectively, a supplying belt is intended to mean a belt which feeds a product carrier to the area in which the transfer of this product carrier to another, removing belt takes place.

In connection with the above-described embodiment, in which guide means are used in order to transfer a transported product carrier from a supplying belt to a removing belt, it should be noted that the use of guide means is known per se . Thus, DE-A-19934361 describes a system of the type described in the preamble in which laterally delimiting guide means are used to control the transfer of a product carrier from a supplying to a removing belt. However, said guide means are fixedly arranged on either side of the belts in the angular region where the latter adjoin one another. The use of rotatably arranged guide means which, in the active position, extend above the surface of a conveyor belt is not discussed nor suggested in said application.

Due to the fact that it makes several (driven) rollers obsolete, the system according to the invention is considerably simpler than the system described in the aforementioned publication and therefore more reliable and less expensive.

Expediently, the product carrier has a square shape and all sides have a hollow incision, the corners optionally being rounded. Such a product carrier which has a basic square shape is obviously advantageous, as such a product carrier can be placed on a conveyor belt at random, without having to ensure that the hollow side is placed on that side of the first belt which also has the projection.

The above-described principle of transferring a product carrier from a supplying conveyor belt to a removing conveyor belt in which the conveyor belts are at an angle to one another, expediently an angle of 90°, can be used with substantially any kind of conveyor belt, irrespective of how this conveyor belt is shaped or driven.

In an attractive embodiment in which guide means are present for the transfer of a product carrier from a supplying to a removing conveyor belt, the supplying conveyor belt is in line with the adjoining removing conveyor belt and the guide means, in the active position, extend above the surface of the supplying conveyor belt.

In another embodiment, the removing conveyor belt is in line with the supplying conveyor belt and the guide means, in the active position, extend above the surface of the removing conveyor belt. In the latter case, however, it is possible to opt for the functional replacement of the guide means by a suitably positioned projection arranged in a fixed position. Of course, as indicated, it is possible to use both guide means and a fixed projection in combination. In particular, each conveyor belt in the above-described system comprises a roller track and an endless belt driving the rollers of this roller track by means of friction with a drive for each endless belt. This conveyor belt is of a conventional type and is highly suitable for use in the above-described system.

In particular, the endless belts in the above-described system have a width dimension which is smaller than the length dimension of the rollers which form part of the conveyor belt.

Advantageously, the width of the endless belts is up to 25% of the length of the rollers, in particular up to 10%.

The width of the endless belt forming part of a conveyor belt is not particularly critical, as long as it is sufficient to create enough friction between a product carrier and said belt.

In the system as described above, the upper sides of the endless belts employed of the supplying and the removing conveyor belt can be at the same height. In order to avoid the risk of the front of a product carrier conveyed on the first endless belt of the supplying conveyor belt knocking against the side of the second endless belt of the removing conveyor belt, it is advantageous if it is for example ensured that the front of a product carrier, which comes into contact first with the second endless belt, is rounded starting from the bottom surface in the direction of the upper surface thereof. Such a rounding is not critical; a radius of curvature which is equal to the thickness of the baseplate of the product carrier may be very expedient, although it is also possible to select different dimensions therefor.

If the endless belt has a width which is smaller than the width of the rollers of the roller conveyor, it may be advantageous if the upper surface of the endless belt of the supplying conveyor belt is slightly higher than the upper surface of the endless belt of the removing conveyor belt. A product carrier conveyed by the first belt can then protrude over a distance up to half the length of the product carrier while it is being transported by the first endless belt and only subsequently come into contact with said second belt, so that adjustment of the friction contact between the product carrier and the second endless belt can only be carried out then. Following this, the hollow side of the product carrier and the fixed projection will start to engage and the product carrier will rotate in order to take up its position on the endless belt on the removing conveyor belt.

As has been said above, the conveyor belt which forms part of the described system may comprise a roller conveyor and an endless belt driving the rollers by means of friction, with each endless belt having a drive. Advantageously, with a conveyor belt of said type to be used, the endless belt is driven by friction by pressing it against a driven drum and kept under tension by using a dancing roller which is carried by arms which are hingedly connected to the frame of the respective conveyor belt. The abovementioned drum may, for example, be driven directly using a three-phase motor with a reduction gear unit.

The above-described drive for an endless belt is extremely simple and reliable and is to a large degree maintenance free.

The friction between the endless belt and the driven drum can preferably be controlled. With a low coefficient of friction between the endless belt and the driven drum, or if there is no friction at all, the endless belt will not be driven and therefore it will not be possible to transport anything on the conveyor track driven by the endless belt, such as the abovementioned roller conveyor. If there is sufficient friction between the endless belt and the driven drum, the endless belt will be driven and will be carried along by the rotation of the drum. Thus, it does become possible to transport something on a conveyor track driven by a belt, such as a roller conveyor. This is advantageous, because a relatively low energy consumption is thus achieved as a result of reduced friction, and furthermore wear is also reduced. Due to the control, it is possible to drive a number of conveyor belts with one single drive unit, while only those conveyor belts are driven which have to move products . The conveyor belts which do not have to move products can be stopped by uncoupling the endless belt from the drive unit.

In one embodiment, pressure-exerting rollers ensure the endless belt is pushed onto the driven drum. A pressing force of the pressure-exerting rollers can be controlled, so that the friction between the belt and the drum can be controlled. The endless belt, the pressure-exerting rollers and the dancing roller are arranged such that the endless belt will follow the position of the pressure- exerting rollers. If the pressure-exerting rollers are a sufficient distance away from the drum, the endless belt will no longer contact the drum. In such a case, the endless belt will no longer be carried along by the drum. Thus, it is possible to drive a number of endless belts of different conveyor tracks using a single driving drum and it is possible to control the drive mechanism of each individual conveyor track using a control system which is coupled to the pressure-exerting rollers associated with each conveyor track.

The invention also relates to a product carrier for use in the above-described system; the product carrier consists of a baseplate and a holder for a product which is centred on the baseplate, and in which a hollow incision is present on at least one side of the baseplate.

Advantageously, the baseplate is square and all sides have a hollow incision, while the holder is shaped such that it can accommodate a plant pot.

The present invention furthermore relates to a workstation which is positioned along a supplying main conveyor track and a removing main conveyor track. The workstation comprises a supplying workstation conveyor track, a removing workstation conveyor track and a working location. The supplying workstation conveyor track is placed between the supplying main conveyor track and the working location. The removing workstation conveyor track is positioned between the working location and the removing main conveyor track.

In one embodiment, the supplying main conveyor track and the removing main conveyor track are the same main conveyor track.

In one embodiment of the above-described workstation, the supplying workstation conveyor track and/or the removing workstation conveyor track work as a buffer between the main conveyor track and the workstation.

In one embodiment, the products on the conveyor track are placed on a product carrier according to the present invention. In a further embodiment, said product carriers are transferred from the supplying main conveyor track to the supplying workstation conveyor track and from the removing workstation conveyor track to the removing main conveyor track by means of a system according to the present invention. The invention will now be described in more detail with the aid of a drawing showing non-limiting embodiments and in which:

Figs. IA, IB schematically show an embodiment of the conveyor belt according to the invention;

Fig. 2 shows an embodiment of a product carrier according to the present invention;

Figs. 3A-3E show the transfer of a product carrier according to Fig. 2 from a supplying to a removing conveyor belt;

Figs. 4A-4C show a drive for an endless belt forming part of a conveyor belt to be used with the system according to the invention; and

Fig. 5 schematically shows a system in which a conveyor belt adjoins both a removing as well as a supplying conveyor belt for a workstation according to the present invention. Fig. IA shows a conveyor belt 1 comprising rollers 2 and an endless belt 3 driving the rollers.

Fig. IB shows a cross section along line B-B of the conveyor belt from Fig. IA. As can be seen, the rollers 2 serve as support for the endless belt 3, while a product carrier 4 is in frictional contact with the endless belt 3. Reference numeral 5 denotes means with which the product carrier can be locked in its path; such locking means are not always strictly necessary and can be omitted in particular in the transfer region between the two conveyor belts.

Fig. 2 shows a product carrier 4 which consists of a baseplate 7 and a holder 8; as can be seen, the basic shape of the product holder is square in this case, all sides have hollow incisions and the corners of the product carrier are rounded. In one embodiment, the product carrier is made from a polypropylene block copolymer which has been stabilized against ultraviolet light, but the product carrier may also be made from any other suitable material.

Figs. 3A-3E show the transfer of a product carrier 4 from a supplying conveyor belt 1 to a removing conveyor belt 10. In the drawing, the conveyor belts 1 and 10 are at an angle of 90°. In one embodiment, the conveyor belts 1, 10 can also be at a different angle to one another.

The conveyor belt 1 comprises rollers 2, an endless belt 3 and a transported product carrier 4. Fig. 3A shows that the product carrier 4 is still on the supplying conveyor belt 1. The removing conveyor belt 10 may be identical to the supplying conveyor belt 1 and comprises rollers 12 and an endless belt 13.

In the corner between the supplying conveyor belt 1 and the removing conveyor belt 10, a projection 14 is arranged in a fixed position which serves as detaining point in order to cause the product carrier 4 to rotate in such a manner that the latter will assume substantially the same position on the removing conveyor belt

10 as it had on the supplying conveyor belt 1. The projection 14 may for example be attached to the frame of one of the conveyor belts.1, 10. It should be noted that the projection 14 is arranged in a fixed position at the moment when the product carrier 4 is transferred from the supplying conveyor belt 1 to the removing conveyor belt 10. If no product carrier 4 is being transferred, the projection 14 may be folded away or recessed, or have been or be brought into a nonfunctional position in any other way. Fig. 3B shows that the product carrier 4, on account of the endless belt 3, has been moved close to the endless belt 13 but that the hollow side of the product carrier 4 does not yet contact the projection 14.

In Fig. 3C, the product carrier 4 has been gripped by the endless belt 13 and the projection 14 contacts the hollow side of the product carrier 4.

Fig. 3D shows that the product carrier 4 has assumed substantially the same position on the conveyor belt 10 which it had on the conveyor belt 1 and to this end has rotated about the fixed projection 14.

Fig. 3E also shows that the upper side of the endless belt which forms part of the conveyor belt 1 is higher than the upper side of the endless belt 13 which forms part of the conveyor belt 10. Particularly when the endless belt, as illustrated here, is narrower than the length of the rollers 2, this difference in height between the upper side of the endless belt 3 and the upper side of the endless belt 13 is advantageous. Said difference in height is obviously not critical and is, for example, between 0.1 and 2.5 cm, expediently the difference in height is 0.2-0.3 cm. Alternatively to the difference in height between the endless belts, it is also possible to opt for bevelling the front of the product carrier (or all sides if the product carrier has a basic square shape as in Fig. 2) .

In order to facilitate the transfer of the product carrier from the supplying conveyor belt 1 to the removing conveyor belt 10 in the embodiment described here, in a preferred embodiment, the width of the endless belt 13 may be chosen to be substantially equal to the length of the supporting rollers. In this manner, it is possible to generate a friction force between the underside of the product carrier 4 and the upper side of the endless belt 13 with only a small overhang of the product carrier 4 on the endless belt 13, so that the transfer can be effected in a quick and reliable manner. Furthermore, it should be noted that the system for transferring a product or product carrier from a first conveyor track to a second conveyor track according to the present invention is not limited to a conveyor track comprising a belt 3 and provided with rollers 12. The present invention can also be used with any other embodiment of a conveyor track. Figs. 4A and 4B schematically show a drive for an endless belt which forms part of a conveyor belt. As can be seen, the endless belt 3 is pressed against a driven drum 20 which will expediently have a length equal to or greater than the width of the endless belt 3. The drum 20 is mounted and the belt 3 is pushed against the drum 20 by means of pressure-exerting rollers. The endless belt 3 is carried along by the drum 20 as a result of frictional contact. In order to ensure that the endless drum 3 remains under tension, a dancing roller 21 is provided which is hingedly arranged relative to the frame of the conveyor belt 1 by means of an arm 22. The weight of the dancing roller 21 is chosen such that the endless belt 3 is kept under sufficient tension. Of course, as an alternative, it is also possible to provide spring means at the hinge point 23 which ensure that the dancing roller 21 is pressed against the rear side of the endless belt 3. Fig. 4B shows the arrangement of the driving drum 20 in more detail; the drum 20 is able to rotate on bearing means 25 while pressure-exerting rollers 26, which are expediently, for example, spring-mounted, ensure that the belt 3 is pressed against the drum 20. In one embodiment, it is possible to control a pressing force of the pressure-exerting rollers 26. To this end, the pressure- exerting rollers may, for example, be provided with an actuator (not shown) which is coupled to a control element (not shown) . Referring to Figs. 4A and 4B, the belt 3 will continue to be pressed against the pressure-exerting rollers 26 by the dancing roller 21, when a space is created between the pressure-exerting rollers 26 and the drum 20, for example by moving the pressure-exerting rollers 26. The friction between the belt 3 and the drum 20 is thus lowered and as soon as the friction drops below a threshold value, the belt 3 will no longer be carried along £>y the movement of the drum 20. Preferably, the belt 3 does not contact the drum 20 when the belt 3 is made to stop in order to prevent wear of the belt 3.

Fig. 4C shows an advantageous embodiment of a conveyor system comprising two conveyor tracks IA, IB. Each conveyor track IA, IB comprises a respective conveyor belt 3A, 3B and rollers 12. The conveyor belts 3A, 3B can be driven by a single driving drum 20 using friction. The friction between the conveyor belts 3A, 3B and the drum 20 is controlled by controlling the pressing force of the pressure-exerting rollers, as shown in Figs. 4a and 4b and as described above. Thus, a single driving element driving the driving drum 20 is sufficient to drive a number of conveyor tracks IA, IB, and the control element can be used to select which conveyor track IA, IB should transport products and which conveyor track IA, IB should be inactive.

Fig. 5 shows a system in which a product and/or a product carrier 4 can be conveyed to a workstation 30. In the system illustrated, a main conveyor belt 1 is, on the one hand, a supplying conveyor belt for transferring a product carrier 4 to a supplying workstation conveyor belt 31; on the other hand, the conveyor belt 1 is a removing main conveyor belt for a removing workstation conveyor belt 32.

As can be seen, a product carrier 4 is fed to the conveyor belt 1 and, in order to be transferred to the supplying workstation conveyor belt 31, guide means 15 are turned from an inactive position 15' ' to the active position illustrated. The guide means are in this case designed as a curved bracket which can rotate about a point of rotation 16 with the aid of, for example, an air cylinder 17, which is situated, for example, under the main conveyor belt 1. Reference numeral 15' denotes fixed guide means which may optionally be added to the rotatably arranged guide means 15. However, they are not strictly necessary.

In one embodiment, the additional guide means 15' is a projection as shown in and described with respect to Figs. 3A-3E. In a further embodiment, the product carrier 4 comprises a substantially rectangular baseplate 7, at least one side of which has a hollow incision, said side with the incision being designed to engage on the projection. In said embodiment, the guide means 15 are designed to engage on a holder 8 of the product carrier 4, which holder is arranged on the rectangular baseplate 7 of the product carrier 4, as shown in and described with respect to Fig. 2. Now referring again to Fig. 5, the guide means 15 in such an embodiment can move easily between a first and a second moving product carrier 4 arranged in succession in the path of the downstream second product carrier 4. The second product carrier 4 can thus be pressed against the projection 15' by the guide means 15 and be guided from the main conveyor belt 1 to the first workstation conveyor belt 31. Of course, in one embodiment, the additional guide means 15' may also have a different shape, while the guide means 15 engage on a holder 8 of a product carrier 4.

Reference numeral 32 denotes a second adjoining workstation conveyor belt which, in this case, is a supplying conveyor belt for the main conveyor belt 1. In this case, the means for transferring the product carrier 4 from the removing workstation conveyor belt 32 to the main conveyor belt 1 consist of a fixed projection 14 which is arranged at the corner of the right angle formed by the two belts.

The fixed projection may, if desired, functionally be replaced by guide means arranged above the conveyor belt 1, which guide means in this case are identical to guide means 15 but arranged mirror- symmetrically relative to an imaginary mirror surface between the conveyor belts 31 and 32.

In two places in the figure, reference numeral 18 denotes a detaining means for a product carrier which serves to detain a product when the conveyor belt is working. The purpose ^• of a detaining means of this type is to detain the product carrier, for example a plant carrier, or a series of plant carriers which are conveyed by a conveyor belt, so that the plant carriers do not collide in the transfer region. The detaining means is moved to the inactive position as soon as there is space on the respective removing belt to receive (a) plant carrier (s) from a supplying belt.

The detaining means 18 can be turned from an inactive position, outside the belt, to an active position above the belt by means of rotation.

Instead of using a detaining means, it is possible, in one embodiment, for a control element to store in a memory at which location on a conveyor belt there is a product carrier and at which location there is no product carrier. In such a case, the control element is able to control the guide means at the moment when no product or product carrier is on the belt at the location of the belt which passes at that particular moment.

The situation depicted in Fig. 5, in which the conveyor belts 31 and 32 serve as removing and supplying belts, respectively, for main conveyor belt 1, makes it possible to withdraw a stream of product carriers 4, with, for example, a plant on each product carrier 4, from the main conveyor belt 1, transport it to the workstation 30 by means of the conveyor belt 31 in order to perform operations or treatments on the plant, transport it away from the workstation 30 by means of the conveyor belt 32 and feed it to the main conveyor belt 1 again. In the workstation, the transfer of product carriers 4 from the conveyor belt 31 to the conveyor belt 32 can be effected using the transfer system according to the present invention as described above; or the transfer can also be effected manually by means of individuals present in or near the workstation. Furthermore, it is possible for the workstation 30 to transport the products or product carriers 4 to another main conveyor belt (not shown) . In one embodiment, the workstation 30 is designed to carry out an assessment of the product and, based on the assessment, to send the product carrier 4 with the product to a first main conveyor belt 1 or to another main conveyor belt (not shown) . Such an assessment and selection system can also be used with the main conveyor belt 1 in order to assess whether or not a product should be transported to the workstation 30 and to control the guide means 15 accordingly.

In one embodiment, the supplying workstation conveyor track 31 serves as a buffer. That is to say that a series of product carriers 4 may assemble on the supplying workstation conveyor track 31 while awaiting treatment at the workstation 30. In a similar manner, a series of product carriers 4 may assemble on the removing workstation conveyor track 32, for example awaiting a suitable opening in a series of product carriers 4 on the main conveyor track 1, if no detaining means is used. In one embodiment, a central control system or control element for this system of belts may turn the detaining means 18 into an active position above the removing workstation belt and detain the product if, for example, there is no space for the product carrier 4 on the belt 32. If there is a space on the receiving main conveyor belt 1 again, the detaining means 18 will turn to the inactive position and thus release the product in order to allow further transportation to the receiving main conveyor belt 1. The abovementioned central control system may comprise tracers in order to detect the presence or absence of product carriers 4 in a certain position on a belt and may control all movements required for the system, such as the movement of the guide means from the inactive to the active position and vice versa; the movement of the detaining means, the movement of the belts, the speed of the belts, etc. In one embodiment, as already mentioned above, a control system or element can store in a memory at which location on the conveyor belts 1, 31, 32 a product and/or product carrier 4 is located. Said tracers or other suitable sensors, such as optical sensors, can be used to gather information and store it in said memory and/or to verify information which has already been stored.

The above-described workstations offer great flexibility when arranging a series of workstations along a conveyor track. For example, a number of workstations at which identical operations are performed can be positioned next to one another and products can be guided to only one of said number of workstations. Thus, a throughput capacity can easily be increased, as said operation can be carried out at different workstations simultaneously, and a product which has already been treated at a first workstation is not guided to a second workstation. Furthermore, products may, as already described above, be guided to a specific workstation or not, based on an assessment.

It should be understood that the embodiments described are only examples of the invention which may be embodied in various embodiments. Therefore, specific structural and functional details which have been disclosed herein should not be seen as limiting, but solely as a basis for the claims and as a representative basis to provide sufficient information to the person skilled in the art to allow him to produce the invention. The terms and phrases used herein are not intended to be limiting, but aim to provide a clear description of the invention.

The terms "a," "an" and "one" as used in this document are defined as one or more than one. The term "number" as used in this document is defined as two or more than two. The term "another" as used in this document is defined as at least a second or more. The terms "comprising" and/or "with" as used in this document do not exclude other components which have not been mentioned (i.e. is not limiting) . The term "coupled" as used in this document is defined as connected, not necessarily directly, and not necessarily mechanically.

Claims

C L A I M S

1. System comprising two conveyor belts (1, 10) adjoining one another at an angle, in which means are present to transfer a product carrier (4) which is movable on a supplying conveyor belt

(1) to a removing conveyor belt (10) on account of the friction force which is exerted by both conveyor belts (1, 10) on the product carrier (4) during the transfer, the product carrier (4) being rotated in order to assume the same position relative to the removing- conveyor belt (10) as to the supplying conveyor belt (1), characterized in that the product carrier (4) is substantially rectangular and at least one of its sides has a hollow incision, whereas the means to transfer the product carrier (4) from the supplying (1) to the removing (10) conveyor belt are selected from:

- a projection (14) which is disposed near the corner of the angle at which the two conveyor belts (1, 10) are to one another and said projection (14) , during at least part of the transfer, is in contact with the side of the product carrier (4) with the hollow incision and

- guide means (15) which are rotatably arranged to move from a position outside one of the conveyor belts (1, 10) to a position where they extend above the surface of a conveyor belt

(1, 10) and said guide means (15) are in contact with at least one corner of the product carrier (4) , during at least part of the transfer and a combination of a projection (14) and guide means (15) .

2. System according to claim 1, characterized in that the product carrier (4) has a substantially square shape, all sides having a hollow incision and/or the corners being rounded.

3. System according to claim 1, characterized in that the supplying conveyor belt (1) is in line with the adjoining removing conveyor belt (10) and the guide means (15) , in the active position, extend above the surface of the supplying conveyor belt (1) .

4. System according to claim 1, characterized in that the removing conveyor belt (10) is in line with the supplying conveyor belt (1) and the guide means (15) , in the active position, extend above the surface of the removing conveyor belt (10) .

5. System according to one or more of claims 1-4, characterized in that each conveyor belt (1, 10) comprises a roller track and a driving endless belt (3, 13) , with a drive (20) for each endless belt (3, 13) .

6. System according to claim 5, in which the driving belt drives the rollers (2, 12) of this roller track by friction and in which the product carrier is driven substantially by friction with the rollers .

7. System according to claim 5, in which the driving belt drives the product carrier by friction and in which the function of the rollers 12 of the roller track is substantially to support a product carrier.

8. System according to claim 5, 6 or 7, characterized in that the endless belts (3, 13) have a width dimension which is smaller than the length dimension of the rollers (2, 12) of a conveyor belt (1, 10) .

9. System according to claim 8, characterized in that the width of the endless belts (3, 13) is up to 25% of the length of the rollers

(2, 12), in particular up to 10%.

10. System according to claim 8 or 9, characterized in that the upper surface of the first endless belt (3) is higher than the upper surface of the second endless belt (13) .

11. System according to one of the preceding claims 5-10, characterized in that an endless belt (3, 13) is driven by friction by pressing it against a driven drum (20) and kept under tension by using a dancing roller (21) which is carried by arms (22) which are hingedly connected to the frame of the respective conveyor belt (1) .

12. System according to claim 11, in which the endless belt (3, 13) is pressed against the drum (20) by at least one pressure-exerting roller (26) .

13. System according to claim 12, in which the pressure-exerting roller (26) exerts a pressing force on the endless belt (3, 13) , which pressing force can be controlled by a controlling element in such a manner that the resulting friction force between the drum (20) and the endless belt (3, 13) can be controlled.

14. System according to claim 13, in which the pressure-exerting roller (26) is displaceably attached to the frame in such a manner that the pressure-exerting roller (26) can be displaced in a controlled manner in order to allow a space between the drum (20) and the pressure-exerting roller (26) to increase.

15. System according to one of the preceding claims, in which the system comprises at least three conveyor belts and a workstation (30) , in which: a first conveyor belt (1) is a supplying main conveyor belt; a second conveyor belt (31) is a supplying workstation conveyor belt which is positioned between the first conveyor belt (1) and the workstation (30) for transporting a product carrier (4) from the first conveyor belt (1) to the workstation (30) ; a third conveyor belt (32) is a removing workstation conveyor belt which is positioned adjoining the workstation (30) for removing a product carrier (4) from the workstation (30) .

16. System according to claim 15, in which the third conveyor belt (32) is positioned between the workstation (30) and the first conveyor belt (1) for conveying the product carrier (4) of the workstation (30) to the first conveyor belt (1) in order to place the product carrier back onto the first conveyor belt (1) .

17. Product carrier (4) for use in a system according to one or more of the preceding claims, characterized in that the product carrier (4) consists of a baseplate (7) and a holder (8) for a product which is centred on the baseplate (7) and at least one side of the baseplate (7) has a hollow incision.

18. Product carrier (4) according to claim 17, characterized in that the baseplate (7) is substantially square and all sides have a hollow incision and the holder is shaped such that it can accommodate a plant pot.

19. Method for treating at least a part of a series of products which are placed on a main conveyor track, the method comprising: guiding a product of the series of products from the main conveyor track to a supplying workstation conveyor track;

- transporting the product on the supplying workstation conveyor track to a treatment location; treating the product at the treatment location; and

- removing the product from the treatment location on a removing workstation conveyor track.

20. Method according to claim 19, in which the removing workstation conveyor track transports the product to the main conveyor track, the method furthermore comprising:

- guiding the product from the removing workstation conveyor track to the main conveyor track.

21. Workstation for use in a conveyor track system, in which the workstation comprises a supplying conveyor track, a removing conveyor track and a treatment location, in which a product or product carrier can be guided from a main conveyor track to the supplying conveyor track using guide means for conveying the product or the product carrier from the main conveyor track to the treatment location and in which the product can be transported from the treatment location by means of the removing conveyor track for removing the product from the treatment location.

22. Driving device for driving a conveyor belt (3, 13), the device comprising: a drum (20) for driving the conveyor belt (3, 13) by friction;

- a drum driving device for driving the drum (20) ; - a dancing roller (21) for keeping the conveyor belt (3, 13) under tension; a pressure-exerting roller (26) for pressing the conveyor belt (3, 13) onto the drum; in which the pressing force of the pressure-exerting roller (26) can be controlled.

23. Driving device according to claim 22, in which the pressing force can be controlled by a controlling element in such a manner that the resulting friction force between the drum (20) and the endless belt (3, 13) can be controlled.

24. System according to claim 23, in which the pressure-exerting roller (26) is displaceably attached to a frame of the driving device in such a manner that the pressure-exerting roller (26) can be displaced in a controlled manner in order to allow a space between the drum (20) and the pressure-exerting roller (26) to increase .