Abstract:
A multi-track tray sealer comprising a lateral tray-contact element which includes a lateral contact surface oriented relative to trays and which is configured such that it is movable in the direction of transport so as to support transport of the trays from a supply conveyor into a sealing tool.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This Application claims priority to German Application Number 102011108919.9 filed Jul. 29, 2011 to Andreas Mader and Alireza Taghipour entitled “Multi-Track Tray Sealer,” currently pending, the entire disclosure of which is incorporated herein by reference. 
       FIELD OF THE INVENTION 
       [0002]    The invention relates to a multi-track tray sealer. 
       BACKGROUND 
       [0003]    Packaging machines of the above-mentioned type with a dual-track layout often have a vertical tray-contact element arranged centrally between the tracks and, on both sides thereof, two externally arranged gripper aims. Trays filled with the product in question are conveyed via two conveyor belts to a position before the sealing device. Subsequently, the gripper arms approach the centrally arranged tray-contact element. In the course of this movement, the trays are seized in a form-fit manner by the gripper arms and pressed against the vertical tray-contact element. The gripper arms then push the trays into the open sealing device, the tray edge located opposite the gripper arms sliding along the tray-contact element. A tray-contact element is also provided in the interior of the sealing device. Trays which have a length that is smaller than the width of the tray in the direction of transport tend to tilt or to slow down when the narrow tray edge slides along the tray-contact element. This leads to twists or jolts in response to which liquid products may spill over the edge. 
         [0004]    EP 1 336 567 A1 discloses a gripper system that seizes the lateral tray edge in a force-fit manner so as to prevent twisting or a tendency to vibrate of the tray. The drawback of this embodiment is an additional clamping unit per gripper arm and an additional moved actuator that is required for this purpose. 
         [0005]    It is therefore desirable for a packaging machine having a multi- or dual-track layout to provide a tray-contact element that provides trays whose length is smaller than its width in the direction of transport to be conveyed in a manner that ensuring reliable processing. 
       SUMMARY OF THE INVENTION 
       [0006]    It is the object of the present invention to improve a dual-track tray sealer with respect to the transport of trays from the supply conveyors into the sealing device such that trays whose length is smaller than their width can be conveyed in a manner ensuring reliable processing. 
         [0007]    The multi-track tray sealer according to the present invention may comprise a gripper system, a sealing tool and a tray-contact element including a lateral contact surface oriented relative to the trays to be conveyed. The contact surface may be configured such that at least certain areas thereof, preferably the contact surface in its entirety, are movable in the direction of transport so as to support the movement of the tray edge abutting laterally on the contact surface. 
         [0008]    The contact surface may comprise a plurality of rollers which minimize the friction occurring between the tray edge and the contact surface. 
         [0009]    According to one embodiment of the sealer of the present invention, the rollers may be provided approximately vertically or at a variably adjustable angle relative to the horizontal, so as to cause the tray to slide upwards on the rollers in the area of the tray-contact element in order to minimize the friction between the tray bottom and the supply conveyor and/or lift the tray bottom off the supply conveyor. 
         [0010]    According to another embodiment, the contact surface may be configured such that two respective vertical conveyor belts cooperate with the gripper system so as to convey the trays. The tray may be movable in a force-fit manner between the gripper system and a conveyor belt thus ensuring reliable processing. Instead of a conveyor belt, a plurality of driven rollers may be provided. 
         [0011]    In this respect, one embodiment may include the speed of the conveyor belts being synchronized with the speed of the gripper system. This allows a synchronous movement of the conveyor belts and of the gripper system in the direction of transport. The gripper arms of the gripper system may cooperate synchronously, or separately—but synchronously—with the respective conveyor belt. 
         [0012]    One embodiment includes the conveyor belts having a common drive; alternatively, in another embodiment, the respective drive can be provided for each of the conveyor belts. 
         [0013]    According to one embodiment, a servomotor may be provided for the drive so as to provide high dynamics in order to allow an increase in the performance of the tray sealer. 
         [0014]    One embodiment includes the conveyor belts having an adherent surface, e.g. a silicone coating, for the tray edges abutting thereon, so that the tray edge can easily be conveyed by means of the conveyor belt. 
         [0015]    In the case of a dual-track layout, the two conveyor belts of the tray-contact element may move in opposite directions of rotation, so that two rows of trays can be supplied to the sealing tool by the gripper system. 
         [0016]    Further, the tray sealer may be conceived that, in the direction of transport, a horizontal support may be provided along the tray-contact element on both sides thereof, for receiving thereon part of a tray bottom during transport so as to lift the tray bottom off the supply conveyor. In this embodiment, the friction with respect to the supply conveyor may be minimized, since, while trays moved by the gripper system are being conveyed, the supply conveyor continues to convey new trays and the gripper system and the conveyor belts may have different speeds. 
     
    
     
       DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0017]    In the accompanying drawings, which form a part of the specification and is to be read in conjunction therewith in which like reference numerals are used to indicate like or similar parts in the various views: 
           [0018]      FIG. 1   a  is a schematic sectional view of a tray sealer in the direction of transport in accordance with one embodiment of the present invention showing the gripper system occupying an open position; 
           [0019]      FIG. 1   b  is a schematic sectional view of the tray sealer of  FIG. 1   a  showing the gripper system occupying a closed position; 
           [0020]      FIG. 2   a  is a schematic perspective view of a tray sealer in the direction of transport in accordance with another embodiment of the present invention in which the tray-contact element consists of conveyor belts; 
           [0021]      FIG. 2   b  is a schematic sectional view of the tray sealer of  FIG. 2   a  showing the gripper system occupying a closed position. 
       
    
    
       [0022]    Identical components are designated by identical reference numerals throughout the figures. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0023]    The invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. For purposes of clarity in illustrating the characteristics of the present invention, proportional relationships of the elements have not necessarily been maintained in the drawing figures. 
         [0024]    The following detailed description of the invention references specific embodiments in which the invention can be practiced. The embodiments are intended to describe aspects of the invention in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments can be utilized and changes can be made without departing from the scope of the present invention. The present invention is defined by the appended claims and the description is, therefore, not to be taken in a limiting sense and shall not limit the scope of equivalents to which such claims are entitled. 
         [0025]      FIG. 1   a  shows a dual-track tray sealer  1  according to the present invention in a vertical sectional view in the direction of transport R. Two parallel supply conveyors  2  have placed thereon tray bottoms  3  of packaging trays  4  to be sealed. A tray-contact element  5  between the supply conveyors  2  may comprise two contact surfaces  5   a ,  5   b  with a plurality of rollers  15  which are inclined relative to a vertical. Gripper arms  6   a ,  6   b  of a gripper system  6  may be externally arranged on either side of and next to the supply conveyors, the gripper arms  6   a ,  6   b  being adapted to be moved in the direction of transport R on the one hand and towards the tray-contact element  5  on the other. Supports  7  are optionally provided between the supply conveyors  2  and the tray-contact element  5 , the supports  7  having a horizontal support surface  7   a  disposed above the conveying plane of the supply conveyors  2 . 
         [0026]      FIG. 1   b  shows a position after the gripper arms  6   a ,  6   b  have moved the trays  4  into contact with the tray-contact element  5 . The right gripper arm  6   a , for example, pushes the tray  4  onto the horizontal support surface  7   a  of the support  7  thus lifting the tray bottom  3  at least partially off the supply conveyor (cf. the view on the right). The gripper arm  6   a  need not push the tray  4  fully into contact with the rollers  15 . 
         [0027]    The effect of lifting the tray  4  in the area of the tray-contact element  5  can also be accomplished without the support  7  (cf. the view on the left). In the case of such an embodiment, the gripper arm  6   a  applies a gentle force to the tray  4  thus pushing it against the rollers  15  in a horizontal direction so that the tray edge  8  abutting thereon can ascend on the inclined rollers  15 , whereby the tray bottom  3  will also here raise, at least in a certain area thereof, from the supply conveyor  2  so as to minimize the friction between the tray  4  and the supply conveyor  2 . 
         [0028]      FIG. 2   a  shows a variant with two parallel supply conveyors  2  that move trays  4 , which are not shown, in the direction of transport R up to a position before the sealing tool  9 . The central tray-contact element  5  comprises here two vertical conveyor belts  11  driven by servomotors  10 . In a downstream direction, two discharge belts  12  are provided after the sealing tool  9 , the discharge belts  12  being used for receiving thereon the trays  4  that have been sealed with a cover film. The sealed trays  4  are transferred by means of the gripper arms  6   a ,  6   b  from the sealing tool  9  to the discharge belts  12 . 
         [0029]    The mode of operation of the embodiment according to  FIG. 2   a  is explained in more detail on the basis of  FIG. 2   b . The gripper arms  6   a ,  6   b  move the trays  4  into contact with the conveyor belts  11  guided around vertical (or, alternatively, slightly inclined) pulleys  13 , so that the tray edge  8  of the trays  4  is pushed against the conveyor belts  11  with a force establishing an adhesion required for the purpose of transport. Alternatively, the trays  4  are only pushed to a position close to the conveyor belts  11 . During transport of the trays  4  in the direction of transport R, the conveyor belts  11  and the gripper arms  6   a ,  6   b  move at a common speed. Therefore, the friction of the tray bottom  3  on the supply conveyor  2  and the discharge belt  12 , respectively, does not have any negative effect, although the supply conveyor  2  and the discharge belt  12 , respectively, may have a different speed and/or an opposite direction of movement. The supply conveyor  2  and the discharge belt  12  are provided with servo drives  13 . 
         [0030]    From the foregoing, it will be seen that this invention is one well adapted to attain all the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the structure. It will be understood that certain features and sub combinations are of utility and may be employed without reference to other features and sub combinations. This is contemplated by and is within the scope of the claims. Since many possible embodiments of the invention may be made without departing from the scope thereof, it is also to be understood that all matters herein set forth or shown in the accompanying drawings are to be interpreted as illustrative and not limiting. 
         [0031]    The constructions and methods described above and illustrated in the drawings are presented by way of example only and are not intended to limit the concepts and principles of the present invention. Thus, there has been shown and described several embodiments of a novel invention. As is evident from the foregoing description, certain aspects of the present invention are not limited by the particular details of the examples illustrated herein, and it is therefore contemplated that other modifications and applications, or equivalents thereof, will occur to those skilled in the art. The terms “having” and “including” and similar terms as used in the foregoing specification are used in the sense of “optional” or “may include” and not as “required”. Many changes, modifications, variations and other uses and applications of the present construction will, however, become apparent to those skilled in the art after considering the specification and the accompanying drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow.