Abstract:
The invention relates to a device for transferring products from a feeder conveyor belt ( 10 ) to a discharge conveyor belt ( 12 ), comprising a linear motor having conveyor elements ( 14 ) which are movably guided on a guide and have grippers ( 18 ) for the temporary accommodation of products ( 20 ). The guide is designed as a linear guide section ( 13 ), and the conveyor elements ( 14 ) can be moved back and forth on the guide section ( 13 ) for picking up and putting down the products ( 20 ). When products ( 20 ) are conveyed consecutively in a row in the conveying direction (z) of the feeder conveyor belt ( 10 ), the feeder conveyor belt ( 10 ), the discharge conveyor belt ( 12 ) and the guide section ( 13 ) are arranged in parallel next to one another, at least in one lateral overlapping area. When products ( 20 ) are conveyed side-by-side in rows in the conveying direction (z) of the feeder conveyor belt ( 10 ), the feeder conveyor belt ( 10 ) is arranged perpendicular to the discharge conveyor belt ( 12 ), and the discharge conveyor belt ( 12 ) and the guide section ( 13 ) are arranged in parallel to one another and are arranged side-by-side with the feeder conveyor belt ( 10 ) at least in a lateral overlapping area.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a device for transferring products from a feeder conveyor belt to a discharge conveyor belt, comprising a linear motor with conveyor elements, which are guided displaceably on a guide and have grippers for temporarily picking up products. A method for operating the device also lies within the scope of the invention. 
     Conventional belt systems are generally used for supplying products, for example chocolate bars which have already been packaged, to a tube packaging machine to produce a multipack. Said belt systems take over the products from the outlet belt of a tube packaging machine, rotate said products, form a short product jam to buffer small fluctuations in the speed, accelerate the products to the speed of the subsequent packaging machine and finally synchronize said products with the feed chain of said machine. A similar problem exists when delivering products from a product array in order to supply said products individually to a tube packaging machine. In this case too, the products are removed from the product array by means of a delivery station, which consists especially of a belt system provided with a switch, and are then aligned, backed up, separated and accelerated by means of a plurality of belts, and synchronized with the packaging machine and passed to the feed chain of the packaging machine. Said systems consist of a multiplicity of belts and thus rapidly reach a length of up to 10 m. 
     The above problems can be solved more compactly by using a feed system consisting of circulating, individual linear motor carriages which grip the products and deposit them directly into the feed chain. In this case, the products can be rotated during the transport path, and synchronization can take place directly by specific acceleration or braking of the individual products in their carriages. Systems of this type are known, for example from U.S. Pat. No. 7,134,258 and EP-A-1 123 886. 
     Disadvantages of this system include the large outlay associated with the circulating linear motor carriages. The feeding of vacuum for gripping the products to a circulating system is demanding, and a large and expensive linear motor section is required for the forward movement and return movement and the two deflections. Also, the carriages which are in circulation at a particular instant are not available, this increasing the number of carriages required and additionally increasing the cost of the system. Furthermore, the deflecting sections are realized only by means of additional technical outlay, since the narrow motor gap required on the deflecting sections between the fixed primary part and moving secondary part of the carriages cannot be ensured. In addition, the circulation requires a comparatively large radius, which makes the entire system have a large overall volume. 
     Furthermore, products can also be placed into the feed chain of a packaging machine by means of a pick and place robot. The disadvantages here include the fact that a vision system, with which the robot can identify the products, is generally required, and the low capacity of approximately 100 products/minute which can be achieved by a robot. In general, however, capacities of 400-800 products/minute are sought, which requires a large number of robots and therefore causes high costs and requires a large amount of space. 
     Groups may also be formed by means of a grouping device, such as a “dancer chain” and transferred by means of a two-axle robot with a multipicker—a “top loader”. The space required and the technical outlay are also large here and the flexibility is restricted. 
     SUMMARY OF THE INVENTION 
     The invention is based on the object of developing a device of the type mentioned at the beginning in such a manner that the disadvantages and costs attached to the linear systems with circulating carriages that are known from the prior art are dispensed with. 
     The object is achieved according to the invention in that the guide is designed as a linear guide section, and the conveyor elements are displaceable to and fro on the guide section for picking up and depositing the products, and, when products are supplied consecutively in a line in the conveying direction of the feeder conveyor belt, the feeder conveyor belt, the discharge conveyor belt and the guide section are arranged parallel next to one another, at least in a lateral overlapping region, and, when products are supplied in rows next to one another in the conveying direction of the feeder conveyor belt, the feeder conveyor belt is arranged perpendicularly to the discharge conveyor belt, and the discharge conveyor belt and the guide section are arranged parallel to each other and are arranged next to each other together with the feeder conveyor belt, at least in a lateral overlapping region. 
     The grippers are preferably arranged on a pivoting arm, which is arranged on the conveyor elements, in order to produce a displacement movement transversely with respect to the conveying direction. The pivoting arm is expediently configured here to execute a pivoting movement which reduces the required movement distance of the conveyor elements for picking up and depositing the products. 
     The grippers may be pivoted, raised and lowered simultaneously via a common drive, in particular via a common driving link. However, the grippers may also be controlled individually via dedicated drives in order to execute pivoting, lifting and displacement movements. 
     Displacement and pivoting movements may also be produced by further linear motors or additional displacement elements. For example, a gripper can be connected to at least two displacement elements via scissors-type kinematics. 
     In a preferred method for operating a device according to the invention, in order to increase the capacity of the device, the movement distances of the conveyor element from product pick up positions to product depositing positions and back are shortened by an overlapping arrangement of a product pick up region and a product depositing region. For optimum operation, the product pick up region and the product depositing region have an arrangement deviating slightly from symmetry. 
     Since there is no circulation, the conveyor elements have to move to and fro between gripping and depositing positions. This would normally lead to a sharp limitation of the production capacity of the system, since some time is required until the conveyor elements, after depositing the products, are available again to pick up new products. 
     However, said waiting times can be minimized by a skillful arrangement, which is explained in more detail further below with reference to  FIG. 3 , of the product pick up and depositing positions and by the proposed construction of the conveyor elements: 
     The depositing section can be arranged in relation to the pick up section in such a manner that the conveyor elements only have to execute a minimum movement such that the conveyor elements, after depositing the product, are rapidly available again at the pick up position. The capacity here is determined by the two outermost conveyor elements which have to cover the greatest distance in order to form the product groups. In this case, the conveyor element which carries out the grouping movement in a direction opposed to the product flow direction has to perform an additional reversal of movement and is subjected to the heaviest load. The optimum arrangement of the pick up and depositing regions is therefore not symmetrical but rather is displaced slightly in the direction of the conveyor element which is subjected to a heavier load such that said conveyor element only has to cover a shorter distance. In an optimum arrangement, the pick up and depositing regions are brought into overlap such that, for example, in the situation in which the pick up and depositing flow are directed in the same direction, the final conveyor element can briefly move backwards during the transformation and is therefore already close again to the pick up position, and the first conveyor element only has to move a little downstream. In this case, the arrangement can be optimized by analysis of the cycle times of the first and of the last conveyor element. This optimization is all the more important the greater the difference in the group width between the pick up and depositing arrangement. 
     Particularly small distances can also be achieved if the pick up and depositing directions are arranged in counterflow, since, in this case, the depositing can take place when all of the conveyor elements are in the return movement to the pick up position. This alternative is advantageous in particular when the products are picked up and deposited approximately at the same distance. 
     Pivoting devices can be attached to the conveyor elements, said pivoting devices, in addition to the transport of the products transversely with respect to the pick up or depositing direction, rotating the products through, for example, 90°. 
     By means of suitable activation of the conveyor elements, empty points in the product feed can be closed such that, even if a product stream has gaps, every depositing position is filled with a product. For this purpose, when an empty point occurs, a conveyor element waits until the next position in the feed, which is provided with a product, comes into the pick region thereof. The further conveyor elements correspondingly grip products at later positions. Similarly, products which are identified as being defective cannot be transferred and packaged since they are jumped over in the same manner as an empty point. 
     Further advantageous refinements of the device according to the invention and of the method according to the invention are the subject matter of dependent claims. 
     The advantages arising inter alia with the device according to the invention include: 
     compact structure 
     defined, gentle, minimum product handling 
     no circulation of the conveyor elements necessary 
     only a comparatively short linear motor module 
     low number of conveyor elements required 
     cost-effective in comparison to circulating alternative 
     more flexible and compact than conventional alternative 
     products are centered at maximum capacity 
     the depositing speed can be adapted to the following machine 
     empty points can be compensated for 
     automatic product rearrangement 
     automatic group rearrangement 
     only non-defective packages are conveyed 
     minimum maintenance, good accessibility 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further advantages, features and details of the invention emerge from the description below of preferred exemplary embodiments and with reference to the drawing which serves merely for explanation and should not be interpreted as being limiting. The drawing shows schematically in 
         FIG. 1  a simplified illustration of a first arrangement for transferring products from a feeder conveyor belt to a discharge conveyor belt; 
         FIG. 2  a simplified illustration of a second arrangement for transferring products from a feeder conveyor belt to a discharge conveyor belt; 
         FIG. 3  an arrangement, corresponding to  FIG. 2  with overlapping product pick up and product depositing regions to optimize capacity; 
         FIG. 4  an oblique view of a third arrangement for transferring products from a feeder conveyor belt to a discharge conveyor belt; 
         FIG. 5  an oblique view of part of the arrangement from  FIG. 4  in an enlarged illustration; 
         FIG. 6  a side view of a detail of the arrangement from  FIG. 4  in the conveying direction of the conveyor belts, in an enlarged illustration; 
         FIG. 7  a top view of an arrangement with two depositing regions; 
         FIG. 8  a side view of a detail of the arrangement from  FIG. 7  in the conveying direction of the conveyor belts; 
         FIG. 9  a simplified illustration of a fifth arrangement for transferring products from a feeder conveyor belt to a discharge conveyor belt; 
         FIG. 10  a simplified illustration of a sixth arrangement for transferring products from a feeder conveyor belt to a discharge conveyor belt; 
         FIG. 11  a simplified illustration of a seventh arrangement for transferring products from a feeder conveyor belt to a discharge conveyor belt; 
         FIG. 12  a simplified illustration of an eighth arrangement for transferring products from a feeder conveyor belt to a discharge conveyor belt; 
         FIG. 13  a first option for processing empty points on a feeder conveyor belt; 
         FIG. 14  a second option for processing empty points on a feeder conveyor belt; 
         FIG. 15  a simplified illustration of a ninth arrangement for transferring products from a feeder conveyor belt to a discharge conveyor belt; 
         FIG. 16  a simplified illustration of a tenth arrangement for transferring products from a feeder conveyor belt to a discharge conveyor belt; 
         FIG. 17  an alternative for loading trays using separating webs. 
     
    
    
     DETAILED DESCRIPTION 
     An arrangement shown in  FIG. 1  shows a feeder conveyor belt  10  moving continuously in the direction of the arrow, and a discharge conveyor belt  12  which is arranged parallel to the former and moves continuously in the direction of the arrow. The two conveyor belts  10 ,  12  lie next to each other and form a lateral overlapping region. A linear motor with a linear guide section  13  as a guide for conveyor elements  14 , which can be displaced to and fro in a controlled manner parallel to the conveyor belts  10 ,  12  on the guide section  13 , is arranged in said overlapping region. Each conveyor element  14  is equipped with a pivoting arm  16  and a gripper  18  which is arranged at the free end of the pivoting arm  16  and is in the form of a vacuum-controlled suction cup. In the arrangement shown, the linear motor is equipped with four conveyor elements  14  which can be activated independently of one another. 
     Packages  20 —In The Present Example Tubular Packages 
     which are arranged consecutively in a line are transported on the feeder conveyor belt  10 . In this case, the feeder conveyor belt  10  corresponds, for example, to a delivery belt for delivering the packages  20  from a tube packaging machine. The conveyor elements  14  use the grippers  18  thereof to simultaneously raise four tubular packages  20  from the feeder conveyor belt  10  (A), and the pivoting arms  16  are pivoted at the same time through 90° (B) and the conveyor elements  14  are moved toward one another in such a manner that the tubular packages  20 , which are now aligned in parallel and perpendicularly to the conveying direction of the discharge conveyor belt  12 , are in contact laterally. The four tubular packages  20  forming one row are deposited onto the discharge conveyor belt (C) and, for example, supplied to a further tube packaging machine for the packaging of every four tubular packages in a multipack. 
     An arrangement shown in  FIG. 2  substantially corresponds to the above-described arrangement of  FIG. 1 . The linear motor is equipped here with  12  conveyor elements  14 . The conveyor elements  14  use the grippers  18  thereof to simultaneously raise  12  tubular packages  20  from the feeder conveyor belt  10  (A), the pivoting arms  16  are simultaneously pivoted through 90° (B) and the conveyor elements  14  are moved toward one another in such a manner that the tubular packages  20 , which are now aligned in parallel and perpendicularly to the conveying direction of the discharge conveyor belt  12 , are laterally in contact. The twelve packages  20  forming a row are deposited onto the discharge conveyor belt (C). 
     The optimization of the system is explained in more detail below with reference to the arrangement which is shown in  FIG. 3  and substantially corresponds to the above-described arrangement of  FIG. 2 . 
     In principle, the product outlet with respect to the product inlet can be 
     directed in the same direction (running in the same direction) 
     at a standstill 
     oppositely directed (running in the opposite direction) 
     located at, for example, a right angle, for example when depositing rows/groups of a plurality of products P on a belt. 
     The various options for the relative position and running direction of the product outlet with respect to the product inlet are illustrated in step C by the different directions of the arrow. 
     As a rule, the depositing region N on the discharge conveyor belt  12  is narrower than the pick up region M on the feeder conveyor belt  10 , i.e. the products P are generally rotated from a longitudinal direction into a transverse direction. If the products P are rotated from a transverse direction into a longitudinal direction, the pick up region is wider than the depositing region and the considerations for optimizing the mutual arrangement of the depositing region N with respect to the pick up region M are correspondingly valid. 
     The capacity of the arrangement is determined in particular by the two outermost conveyor elements on the right F 1  and left F 12 , since said conveyor elements cover the greatest distances. 
     In the example shown in  FIG. 3 , the products P are moving to the right in the inlet and in the outlet. In this case, it is obvious to connect the depositing region to the pick up region, i.e. the conveyor elements move exclusively to the right from picking up the products to depositing the products. However, this has the consequence that the conveyor elements have to cover a large distance to the left back to the pick up points or pick points thereof. 
     According to the invention, the pick up region M and the depositing region N are therefore arranged in overlapping manner—as shown in  FIG. 3 —i.e. the depositing region N is located approximately symmetrically in the center of the pick up region M, or is offset slightly to the right, since the outermost right conveyor element F 1  is exposed to the greatest dynamic loading because of an addition reversal of movement and should therefore preferably cover a somewhat shorter distance than the outermost left conveyor element F 12 . 
     The movement sequence of the outermost right conveyor element F 1  can be characterized as follows: 
     1. The conveyor element F 1  synchronizes at high speed with the product  1  in the direction of the product flow. 
     2. Reversal of the movement, the conveyor element F 1  travels back, since the depositing point thereof is located to the left of the pick up point. 
     3. The conveyor element F 1  accelerates again in the direction of the product flow, but now at the lower depositing speed, and deposits the product P 1 . 
     4. The conveyor element F 1  moves back to the pick up point or pick position, with virtually no more travel being required here, or at most a short travel forward or back. 
     The movement sequence of the outermost left conveyor element F 12  can be characterized as follows: 
     1. The conveyor element F 12  synchronizes at high speed with the product  12  in the direction of the product flow. 
     2. The conveyor element F 12  moves further in the direction of the product flow, but reduces the speed to the depositing speed, since the depositing point thereof is located to the right of the pick up point, and deposits the product P 12 . 
     3. The conveyor element F 12  now reverses the direction of movement and moves back to the pick up point or pick position. The distance back is relatively short because of the overlapping arrangement of the product pick up and product depositing regions. 
     If the depositing region N is displaced further to the right, this is more favorable for the right conveyor element F 1 , and if said depositing region is displaced again further to the left, this is more favorable for the left conveyor element F 12 . The optimum region can be determined for a particular application by analysis of the dynamics or by simulation. 
     The movement distances covered by the two outermost conveyor elements F 1  and F 12  during a pick up and depositing cycle are illustrated in the drawing by lines with directional arrows. 
     The remaining conveyor elements F 2  . . . F 11  move between said two outermost conveyor elements F 1  and F 12  and are therefore not critical for optimizing the capacity. 
       FIGS. 4, 5 and 6  show an arrangement which corresponds to the arrangements of  FIGS. 1 and 2  and has three conveyor elements  14 , the lifting and pivoting movement of which takes place via a common link control  22 . In the arrangement shown, the conveyor elements  14  have a pivoting mechanism for producing a lift transversally with respect to the transport direction. The raising of the packages  20  using grippers  18  from the feeder conveyor belt  10  and the depositing onto the discharge conveyor belt  12  takes place via a first link control element  24 , and the rotation of the pivoting arm  16  takes place via a second link control element  26 . The individual conveyor elements  14  can be displaced in a controlled manner independently of one another along the guide section  13  of a linear motor. 
       FIGS. 7 and 8  show an alternative of an arrangement with two depositing positions. One discharge conveyor belt  12   a ,  12   b  is located on each side of the feeder conveyor belt  10 . In the embodiment shown in  FIG. 7 , the pivoting arm  16  is rotated via a driving unit  27 . 
     The arrangement shown in  FIG. 9  substantially corresponds to the arrangement of  FIG. 2 . The twelve conveyor elements  14  use the grippers  18  thereof to simultaneously raise  12  packages  20  from the feeder conveyor belt  10  (A), the pivoting arms  16  are simultaneously pivoted through 90°, and the conveyor elements  14  are moved towards one another in such a manner that the packages  20 , which are now aligned in parallel and perpendicularly to the conveying direction of the discharge conveyor belt  12 , are in contact laterally. The  12  packages  20  forming a row are deposited onto the discharge conveyor belt (B). The optimization, which has already been described in conjunction with  FIG. 3 , of the product transfer from the feeder conveyor belt  10  to the discharge conveyor belt  12  by means of reduced movement of the conveyor elements  14  can readily be seen in the drawing. 
       FIG. 10  shows an arrangement in which the feeder conveyor belt  10  meets the discharge conveyor belt  12  perpendicularly, and in each case a row of 19 products arranged next to one another is simultaneously picked from the feeder conveyor belt  10  by 19 conveyor elements  14  and, after rotation through 90°, deposited simultaneously in a line on the discharge conveyor belt  12 . This is apparent from the drawing without the optimum manner of movement of the 19 conveyor elements  14 . 
     In the arrangement which is shown in  FIG. 11  with a parallel arrangement of the feeder conveyor belt  10  and discharge conveyor belt  12 , three conveyor elements  14  can be displaced independently of one another along the guide section  13 , which is arranged parallel to the conveyor belts  10 ,  12 , of a linear motor. Each of the three conveyor elements  14  is equipped with a pivoting arm  16  having a triple-action gripper  18 . The triple-action grippers  18  pick up one package  20  each three times simultaneously from the feeder conveyor belt  10  (A, B, C), the pivoting arms  16  each being pivoted at the same time for the further picking up of the products. When the triple-action grippers  18  are each occupied with three packages  20 , all of the pivoting arms are pivoted simultaneously through 90°, and the packages  20  are deposited, rotated through 90°, in groups of three on the discharge conveyor belt  12  (D). 
     The arrangement shown in  FIG. 12  differs from the arrangement according to  FIG. 11  in that, instead of three conveyor elements  14  each having a triple-action gripper  18 , there are four conveyor elements  14  having double-action and triple-action grippers  18  in an alternating manner. In the example illustrated, groups of up to five packages  20  are deposited on the discharge conveyor belt  12  by in each case two conveyor elements  14  having double-action and triple-action grippers  18 . In order for the packages to be picked up by the multi-action grippers  18 , the conveyor elements  14  are each displaced by a corresponding distance perpendicularly to the conveyor belts  10 ,  12 . It can readily be understood from the drawing that, with the combination of two and 3 grippers  18 , all configurations having more than two products per group can be formed. 
     Instead of the picking up, which is shown in  FIGS. 11 and 12 , of a plurality of products and depositing said products in groups on a plane, a plurality of products can also be picked up by stacking grippers and deposited as a stack. 
     It can be seen from  FIG. 13  how missing packages or empty points on the feeder conveyor belt  10  are compensated for in an arrangement with a linear motor having a linear guide section  13  and four conveyor elements  14  or pickers F 1  . . . F 4 . In the standard mode, there are no empty points on the feeder conveyor belt  10 , and the four conveyor elements  14  use the grippers  18  thereof, which are fastened to pivoting arms  16 , to simultaneously raise four consecutive packages  20 . In the example shown, there is an empty point L between two packages  20 . The pickers F 1  . . . F 3  are accelerated and synchronized with the associated three packages  20  on the feeder conveyor belt  10  to the right of the empty point L while the picker F 4  waits in the starting position (A, B). The three packages  20  are picked, the pickers F 1  . . . F 3  are pivoted, delayed and remain in a waiting position (C). The picker F 1  is subsequently accelerated and synchronized with a package  20  to the left of the empty point L. The package  20  is picked and brought up to the three packages  20  in the waiting position (D, E). The system subsequently runs again in the standard mode (A′). 
     In the empty point processing alternative shown in  FIG. 14 , the pickers F 1  . . . F 3  are accelerated and synchronized with the associated three packages  20  on the feeder conveyor belt  10  to the right of the empty point L (A). The three packages  20  are picked and the pickers F 1  . . . F 3  remain in a waiting position (B). The picker F 1  is then accelerated and synchronized with a package  20  to the left of the empty point L. The package  20  is picked and brought up to the three packages  20  in the waiting position (C). The pickers F 1  . . . F 4  are now decelerated and jointly pivoted for depositing the products on the discharge conveyor belt  12  (D, E). The system subsequently runs again in the standard mode (A′). 
     In the arrangement, which is shown in  FIG. 15 , with a parallel arrangement of the feeder conveyor belt  10  and discharge conveyor belt  12 , sixteen conveyor elements F 1  . . . F 16  can be displaced independently of one another along the guide section  13  of a linear motor, which guide section is arranged parallel to the conveyor belts  10 ,  12 , and are divided into two picker groups each having eight conveyor elements F 1  . . . F 8 , F 9  . . . F 16 . Each of the sixteen conveyor elements  14  is equipped with a pivoting arm  16  having a gripper  18 . The picking and pivoting movement is triggered by fixed radial cams or fixed links  28 ,  30 . The products are therefore picked at defined locations of the mechanism and rotated at a defined location. Since the pick position cannot be changed, each product has to be picked at the precisely correct time, namely when the product in the inlet is located at the pick position. In order to be able to pick all of the products, at least two picker groups having two radial cams  28 ,  30  have to be used because of the time required for the return movement of the picker groups. 
     The arrangement shown in  FIG. 16  differs from the arrangement according to  FIG. 15  in that the radial cams or links  28 ,  30  can be displaced along the guide section  13  of the linear motor. The pick and pivoting movement is triggered by the linearly displaceable radial cams  28 ,  30 . The positions at which the products are gripped or deposited can therefore be displaced and adapted to the current product position. A time window for the picking operations is therefore available. In order to be able to pick all of the products, at least two picker groups having two radial cams have to also be used here because of the time required for the return movement of the picker groups. In order to obtain a short design, for each product the pick position is advantageously displaced counter to the product flow direction. The distance d between the two picker groups, and therefore the length of the system, can thus be kept to a minimum without the picker groups colliding. The short overall length means that the pickers also have to cover less distance, and therefore this alternative obtains a greater capacity in comparison to the alternative having fixed radial cams. The arrangement is very compact, and the length f is shorter than the length c in the arrangement according to  FIG. 15  having fixed radial cams. 
       FIG. 17  shows an alternative of the loading of trays  32  when direct loading at the desired distance is not possible because the distance is smaller than the width of the conveyor elements or the minimum distance between the conveyor elements. Therefore, for example, in a first step, only every second or every third etc. position is loaded and, subsequently, in a second step or in subsequent steps, the remaining gaps are then loaded. Should the products slip if they are not fixed, it is possible to insert, for example, separating webs  34  which are removed again after the loading, for example by being retracted.