Abstract:
A gripper system for improving the picking up of a product, in particular of an elastic article. The gripper system having a gripper, wherein the gripper comprises an endless transport belt and a lever system. The lever system includes a rotatably supported lever, a support and an entrainer configured to entrain the transport belt, wherein the lever is connected to the support such that, in response to a linear movement of the support, the lever will be rotated about a center of rotation. The lever is additionally connected to the entrainer such that the transport belt moves in response to the rotational movement of the lever.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This Application claims priority to German Application Number 102011109967.4 filed Aug. 2, 2011 to Michael Lang entitled “Gripper System,” currently pending, the entire disclosure of which is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The invention relates to a gripper system that can be used e.g. for picking up, conveying and putting down products in automatic packaging or production plants. 
     BACKGROUND 
     A gripper system with a transport belt for picking up products is described in EP 1 986 941 A1. The gripper system includes a transport belt which is tensioned around a plate. For picking up a product to be conveyed, the plate is pushed below the product; whereby the transport belt moves relative to the plate. This arrangement largely avoids a relative movement between the transport belt and the product. It is, however, disadvantageous in so far as picking up of a product that is not additionally supported. A similar gripper system is disclosed by EP 0 063 400 B1. 
     There is therefore a need in the art for a gripper system that is configured to pick up products that are not additionally supported. 
     SUMMARY OF THE INVENTION 
     It is the object of the present invention to provide a gripper system which improves the picking up of a product, in particular of an elastic article. 
     The gripper system according to the present invention comprises a gripper including an endless transport belt and a lever system. The lever system may comprise a rotatably supported lever, a support and an entrainer entraining the transport belt, the lever may be connected to the support such that, in response to the linear movement of the support, the lever may be rotated about a center of rotation. In addition, the lever may be connected to the entrainer such that the transport belt will move in response to the rotational movement of the lever. This system may be advantageous insofar as the lever system, which acts as a transmission mechanism, allows a movement of the support that causes in a movement of the transport belt. This can advantageously be used when a product is picked up, since the product is pulled onto the gripper in response to the movement of the transport belt. In view of the fact that an oppositely directed movement of the transport belt is caused when the product is put down, a product that has been extended during picking up would be compressed to the same extent during putting down. 
     For moving the support rapidly and efficiently, a pneumatic cylinder connected to the support may be provided. 
     In order to accomplish a robust transmission of force from the support to the lever, it may be expedient to provide a first contour on the lever, a first pin, which is connected to the support, moving along the first contour. 
     According to a preferred embodiment, the first contour is curved in shape so as to accomplish by means of the curved shape of the contour an adequate transmission function for the lever system, similar to a slotted link control. 
     Alternatively, a second contour may be provided on the lever, a second pin, which may be connected to the transport belt, moving along this second contour. Due to the fact that the second contour can be designed freely, this arrangement leads to a flexible control of the transport belt. Furthermore, weight is saved through the additional opening provided on or in the lever, and, consequently, lighter masses are accelerated which may increase efficiency. 
     The first and/or the second contour may be configured as a groove or slot on or in the lever. This promotes a reliable engagement between the pin and the contour. Due to the higher weight reduction and the resultant reduction of the accelerated masses, a slot may also have a positive effect on the movement characteristics of the gripper system. 
     In order to realize the lever system in a space-saving manner on or in the gripper, the lever may be angular in shape. 
     The lever may comprise a first and a second arm, said first and second arms being arranged in an L-shaped configuration and a center of rotation being provided between said first and said second arm. 
     For picking up elastic objects it may be expedient for the transport belt to have movement of a certain range in a direction opposite to the direction of the linear movement of the support. One embodiment includes a range of around fifteen millimeters (15 mm); however, any length of movement is within the scope of the present invention. One benefit of this range is that the height of the plate, which is enclosed by the endless transport belt of the gripper, can be overcome and the lifting of the object to be picked up is improved through additional pulling by means of the transport belt. 
     Since the objects to be picked up differ from one another in their elasticity and their physical consistency, it may make sense that the length of the movement of the support is adjustable so as to provide a desired distance of movement of the transport belt. By means of this adjustment, the resulting compression and extension of the object to be picked up can be controlled in each individual case. 
     For a uniform, non-tilting movement of the transport belt an additional lever system may be arranged on the gripper, wherein the additional lever system may be arranged as a mirror image of the first lever system relative to the transport belt. 
     For protecting the movable parts of the lever system, a housing may be provided for the gripper system. 
     For improved picking up of the product, a second gripper may additionally be provided, said second gripper being arranged as a mirror image of the first gripper. The object or product to be picked up is located between the first and the second gripper just before it is picked up by one of the grippers or both. 
     Other and further objects of the invention, together with the features of novelty appurtenant thereto, will appear in the course of the following description. 
    
    
     
       DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       In the accompanying drawings, which form a part of the specification and are to be read in conjunction therewith in which like reference numerals are used to indicate like or similar parts in the various views: 
         FIG. 1  is a perspective view of one embodiment of a gripper system in accordance with one embodiment of the present invention; 
         FIG. 2  is a side view of the gripper system of  FIG. 1  showing the lever system at a starting position; 
         FIG. 3  is a side view of the gripper system of  FIG. 1  showing the lever system at an intermediate position; and 
         FIG. 4  is a side view of the gripper system of  FIG. 1  showing the lever system at an end position. 
     
    
    
     Identical components at designated by identical reference numerals throughout the figures. 
     DETAILED DESCRIPTION OF THE INVENTION 
     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. 
     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. 
       FIG. 1  shows a perspective view of a gripper system  1  according to the present invention. The gripper system  1  can be used for picking up, conveying and putting down articles or products, which may e.g. be foodstuffs. The gripper system  1  is especially intended to be used for conveying elastically yielding foodstuffs, such as pieces of meat. 
     The gripper system  1  comprises a central body  2  having on the upper side thereof a connection  3  for supplying power or pressurized air to the gripper system  1 . The central body  2  is additionally provided with two parallel guide rods  4 , which are partially enclosed by the central body  2  and which extend along the lower longitudinal side of the central body  2 . The guide rods  4  project beyond the central body  2  on at least one end thereof. 
     On the lower side of the central body  2 , a gripper  5  is linearly movable along the guide rods  4 . For moving the gripper  5 , e.g. a pneumatic cylinder  5   a  or an electric motor, which is not shown, may be provided. The guide rods  4  extend through openings  6  of the gripper  5 . On an end of the guide rods  4  projecting beyond the central body  2 , the guide rods  4  have secured thereto a stop plate  7  on the outer side of the central body  2 . On the end of the guide rods  4  located opposite the stop plate  7 , a stop device  4   a  is provided as a limit point for the gripper  5 . The gripper  5  thus moves between an open position at the end of the central body  2  located opposite the stop plate  7  (shown in  FIG. 2 ) and an end position at the stop plate  7  (as shown in  FIG. 4 ). 
     The gripper  5  has, on either of its two lateral ends, a respective arm  20  used for securing a plate  11  thereto. The belt fastening units  8  extend downwards from the side of the central body  2  and are angular in shape. A first portion  8   a  of the belt fastening unit  8  extends downwards, a second portion  8   b  follows the first one at an angle thereto and extends substantially horizontally and parallel to the guide rods  4 . The second portion  8   b  of the belt fastening unit  8  is provided with a guide  9  in the form of an elongated hole whose function will be described hereinbelow. 
     The gripper  5  comprises an endless transport belt  10  made from a material which is suitable for use with foodstuffs and which is in conformity with applicable U.S. regulations, such as those of the Food and Drug Administration. The transport belt  10  is tensioned around the plate  11  without being firmly connected to said plate  11 . The plate  11  extends between the two belt fastening units  8 , so that the plate  11  including the transport belt  10  is arranged between the belt fastening units  8 . Plate may be made from a plastic material, a metal or any other material suitable for the intended use. 
     The transport belt  10  has secured thereto a tunnel-shaped bag  12  which extends across the whole width of the transport belt  10  and of the plate  11 . The tunnel-shaped bag  12  has a respective open end in the area of the belt fastening units  8 . An entrainer  13  may extend through the bag  12  from one belt fastening unit  8  to the opposite belt fastening unit  8 . At least one end of the entrainer  13  may be received in and guided by the elongated hole  9 . The elongated hole  9  is arranged in the lower portion  8   b  of the belt fastening unit  8  and guides the entrainer  13 . One embodiment of entrainer  13  is a metal rod. 
     The gripper  5  additionally comprises a lever system  14 , which is arranged on one side of the gripper  5  in this embodiment. Alternatively, an additional lever system may also be arranged, as a mirror image of the first lever system  14 , on the gripper side opposed to the first lever system  14 . The lever system  14  arranged on the outer side of the belt fastening unit  8  includes an L-shaped lever  15 . The lever  15  comprises two arms  16 ,  17 , each provided with a contour  18 ,  19  having the shape of a slot. The contour  18  of the first arm  16  is curved within itself, whereas the contour  19  of the second arm  17  is substantially straight in shape relative to the arm  17 . 
     In addition, the lever system  14  is provided with a support  20  on either side of the transport belt  10 . The plate  11  extends between the two supports  20  and is secured to these two supports  20 , e.g. by a clamp connection. The lever  15  is arranged outside the support  20 . The support  20  arranged on the side of the lever  15  is connected to said lever  15  by means of a pin  21 . To establish a form-fit connection, the pin  21  may engage the contour  18  of the first arm  16 . Pin  21  can additionally be secured to the lever  15  by a force-fit connection, such as a pin retainer mechanism. The lever system  14  essentially functions similar to a slotted link control. 
     In the embodiment illustrated in  FIG. 1 , the support  20  is further connected to the pneumatic cylinder  5   a . However, in an alternative embodiment when the gripper system  1  is electrically operated, the support  20  may be connected to an electric motor. The pneumatic cylinder  5   a  is secured to the gripper system  1 . 
     In use, the gripper system picks up a product  24 .  FIG. 2  shows the gripper system  1  in an open position wherein the gripper  5  is located at one end of the guide rods  4 . At this position, the pneumatic cylinder  5   a  is at an extended position. In this position of the gripper system  1 , the pin  21  is located at a first end of the first contour  18 . Another pin  23 , which is connected to the entrainer  13 , brings the second contour  19  of the lever  15  into engagement with the elongated hole  9  of the belt fastening unit  8 . Also, at the open position, the pin  23  is at a non-activated position at a first end of the elongated hole  9 . 
     Starting from the open position shown in  FIG. 2 , the gripper system  1  is able to pick up a product  24 . The gripper  5  and the support  20 , respectively, move along the guide rods  4  towards the stop plate  7  in response to actuation of the pneumatic cylinder  5   a . This movement of the gripper  5  moves the plate  11  towards the product  24  to be picked up and creates a relative speed between the plate  11  and the transport belt  10  as the transport belt  10  moves around the plate  11 . 
       FIG. 3  shows a position of the gripper system  1  occupied by the latter while the product  24  is being picked up. To get from the open position to the pick-up position, the pneumatic cylinder  5   a  moves the support  20  together with the pin  21  towards the stop plate  7 . The pin  21  thus moves along the contour  18  causing the lever  15  to be rotated counter-clockwise about a center of rotation  25 . The center of rotation  25  is located between the two arms  16 ,  17 . In response to this rotational movement, the pin  23  slides along the elongated hole  9  in a direction opposite to the direction of movement of the pneumatic cylinder  5   a  and of the support  20 . 
     The pin  23  is connected to the entrainer  13 , whereby the bag  12  and, consequently, the transport belt  10  move together with the pin  23  in the same direction, which is opposed to the direction of movement of the support  20 . The curved shape of the first contour  18  of the lever  15  here has the effect that the lever  15  will first rotate at a higher speed around the center of rotation  25  and that, consequently, the transport belt  10  will move faster relative to the plate  11  and the product  24 . If the contour  18  were not curved, no relative speed between the transport belt  10  and the product  24  would occur. The curved contour  18 , however, results in a higher speed of the transport belt  10  relative to the product  24 , whereby the thickness of the plate  11  can be overcome more easily by the product  24 . The product  24  is thus partially pulled onto the plate  11  by the transport belt  10 . The decisive factor for the height of the speed and the distance over which the transport belt  10  is accelerated is the curved contour  18  of the lever  15 . 
     As soon as the pin  21  has passed the bend of the contour  18  and is located in an area of the contour  18  which is parallel to the lower portion  8   b  of the belt fastening unit  8 , the transport belt  10  is no longer accelerated, whereby the relative speed between the transport belt  10  and the product  24  is eliminated. This means that, although the plate  11  still moves relative to the product  24 , the transport belt  10  no longer moves relative to the product  24 . The plate  11  is advanced to a position further below the product  24 . This prevents further deformation of the product  24 . 
     The picked-up product  24  can now be transported to its destination by the gripper system  1 . At this destination, the pneumatic cylinder  5   a  is retracted, whereby the pin  21 , which is connected to the support  20 , follows the contour  18  in a direction opposite to the pick-up edge of the plate  11 . As long as the pin  21  has not yet reached the bend of the contour  18 , no relative speed will occur between the transport belt  10  and the product  24 . When the pin  21  has overcome the bend of the contour  18 , the transport belt is reaccelerated, whereby a relative speed occurs between the transport belt  10  and the product  24 . If, due to the acceleration, the product  24  should have been deformed and/or extended during picking up, the product will now undergo an opposite deformation and/or compression due to the acceleration in the opposite direction. Since also the gripper  5  moves back to the starting position, the product  24  is put down at its destination due to the withdrawal of the plate  11 . 
     Starting from the embodiment shown, the gripper system  1  according to the present invention can be modified in many ways. For example, the lever system  14  may be provided on either side of the transport belt  10 . In addition, gripper  5  may be provided in duplicate on the central body  2  of the gripper system  1 , wherein the second gripper replaces the stop plate  7  of the above embodiment. Further, entrainer  13  may be of another shape, including the shape of the plate. 
     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. 
     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.