Abstract:
A gripper unit for transport systems for supporting and transporting articles. A gripper unit that includes a gripper head with at least two gripper arms which can be opened and closed against each other. The top of the article to be gripped and to be transported is supported in the opening formed between the gripper arms. A shifting unit is supported in a flexible manner via a fastener directly supported at the transport system. Furthermore, the gripper unit is provided with a device for interchangeable support, adjustment and spatial determination of the gripper head in a first transport direction at the gripper unit. The device provides for the vertical movement of the gripper head contrary to the gripper unit and/or contrary to the transport system, which are arranged between the gripper head and the shifting unit or between the gripper head and the transport system.

Description:
This claims the benefit of German Patent Application 10 2009 043 984.6, filed Sep. 11, 2009 and hereby incorporated by reference herein. 
     The present invention relates to a variable and interchangeable gripper unit for transporting articles, particularly bottles. 
     BACKGROUND 
     In the packaging industry, particularly with the production and filling of bottles, said bottles must be transferred from a first processing device to a second processing device at high speeds. For this purpose, transfer systems such as, for example, so called infeed and discharge starwheels with gripper heads are used, as shown in WO 2008/129347. The gripper heads grip the empty or already filled bottles at the neck below the upper opening, in fact preferably below the neck region where the bottles are provided with an enlargement. Generally, this is also known as ‘neck handling’. 
     EP 0 939 044 B1 shows a bottle gripper with two grab arms, with contact faces for a control cam. Each contact face is part of an elastic pad fastened to the grab arm. The pad consists of an elastomeric material, and the contact face is of a low-wear material. The elastic pad is formed by a leaf spring bent about the grab arm, and held positively and in a removable manner in a holder in the grab arm. The grab arms are pivoted tongue-like about one or two pivot points, forming a grab section and an operating section. 
     DE 101 40 315 A1 shows a gripper for transporting plastic bottles. The gripper has two arms mounted on vertical pivots. The gripping surfaces contact the neck of the bottle at three or more points which lie in the same plane. 
     EP 0 854 102 B1 shows a container gripper, in particular for bottles, which is positionable on a movable part of a manipulating machine, and comprises a support structure internally carrying a pair of arms driven to rotate between a closed rest position in which they face each other to retain the container, and an open position in which they are withdrawn from each other to release the container; in this gripper the support structure comprises a U-shaped bracket supporting a limit stop. 
     U.S. Pat. No. 7,261,199 B1 shows a conveyor with grippers, which also grips the containers at the neck. The grippers are arranged at connected links and are positioned movable relative to their respective links for gripping a container by the neck of the container. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a rapidly variable and interchangeable gripper unit. 
     The present invention provides a gripper unit for transport systems for supporting and transporting articles. The gripper unit can be installed, for example, at starwheel-shaped transport systems, wherein the starwheel-shaped transport systems serve for transferring articles, for instance blown containers such as empty or filled bottles, from a first processing device to a second processing device. Such infeed and discharge starwheels respectively are used, for example, between a blow-mold machine where bottles are made of preforms, and a filling station installed subsequently to said blow-mold machine. A further usage of such gripper units is to be found within blow-mold machines, wherein either preforms are inserted into the blow-mold or bottles are removed from the blow-mold. 
     A gripper unit according to the invention comprises a gripper head, wherein said gripper head is provided with at least two gripper arms which can be opened and closed against each other. The article to be gripped and transported is supported in the opening formed in between the gripper arms. Preferably, the top of the articles is supported. However, with a modified gripper unit also a support of the article to be transported is possible in the body region of said article. 
     The gripper unit comprises a shifting unit and/or a fastening means. The shifting unit can be directly or indirectly supported in a flexible manner at the transport system via a fastening means which is arranged in between, for example. According to a preferred embodiment, a gripper unit includes a gripper head, a shifting unit and a fastener or fastening means, wherein preferably a second movable component (which is described in greater detail below) is possible between the shifting unit and the fastener. The shifting unit provides constant shifting of the gripper head during a production process. 
     Furthermore, the gripper unit has means for interchangeable support, adjustment and spatial determination of the gripper head in a first transport direction at the gripper unit. According to a preferred embodiment of the invention, the means provide a vertical movement of the gripper head contrary to the gripper unit and/or the transport system. 
     According to a preferred embodiment, the means for interchangeable support, adjustment and spatial determination of the gripper head are arranged between the gripper head and the shifting unit. Alternatively, the means for interchangeable support, adjustment and spatial determination of the gripper head can be directly arranged between the gripper head and the transport system. 
     The means for interchangeable support, adjustment and spatial determination of the gripper head are preferably molded parts for forming a dovetail joint, wherein said molded parts can be determined by means of a clamping device in a spatial position. In particular, a dovetail section is provided at the gripper head, whereas the shifting unit or the transport system is provided with the corresponding counter piece. Alternatively, the dovetail section can be arranged at the shifting unit or at the transport system, of course, whereas the gripper head is provided with the corresponding counter piece forming a dovetail groove. 
     The means for interchangeable fastening are adjusted and fastened in a respective manner during a production downtime and remain during production in the determined position. 
     The clamping device can be a clamping screw, for example, wherein said clamping screw can be both determined at the molded part with the dovetail section, and at the corresponding counter piece. Said clamping device provides the fixation of the dovetail joint in the adjusted spatial position. Further known fixing means known to a person skilled in the art shall also be covered by the invention. 
     Besides, the means for interchangeable support, adjustment and spatial determination of the gripper head encompass preferably a limit stop for height adjustment and for easy replacement of the gripper head. According to a preferred embodiment, the limit stop is designed as an adjusting screw with which the axial run-out of the gripper head can be adjusted. In turn, the position of the limit stop can be fixed and determined by means of a laterally arranged clamping screw. 
     According to a further preferred embodiment, the gripper unit is furthermore provided with means for shifting in a second transport direction. Preferably, these means provide the horizontal shifting of the gripper head contrary to the transport system. 
     According to a preferred embodiment of the invention, the first transport direction of the gripper head and the second transport direction of the gripper head are perpendicular to each other. In particular, the first transport direction of the gripper head can provide a vertical movement and the second transport direction a horizontal movement. 
     The means for shifting in a second transport direction are preferably provided between the shifting unit and the fastening means, and encompass, for example, a guide rail, which enables a movement of the gripper head in direction of the fastening means already described above and/or in direction of the transport system, and from said transport system respectively. 
     In order to facilitate the movement in the second transport direction, the fastening means or the transport system are provided with elements, which engage into the guide rail of the shifting unit and are shiftable therein. Said elements can be rollers or the like, for example, which proceed in the guide rail of the shifting unit. 
     The distance between gripper head and transport system can be particularly varied by means of the second movable component. This is necessary, for instance, in order to avoid a collision when articles are transferred from one transfer starwheel to another transfer starwheel, or to a processing unit. For this purpose, rollers can be provided at the shifting unit and/or at the fastening means, which guide the gripper unit in special transport guide rails and thus always exactly determine the horizontal distance between gripper head and transfer system. 
     Furthermore the invention relates to a gripper head to be fastened at a transport system for supporting and transporting articles. The gripper head can be directly supported at the transport system, or by an already above-described dovetail joint via intermediate elements at the transport system. The intermediate elements can be, for example, the already described shifting unit and/or fastening means. 
     According to a preferred embodiment, the gripper head is provided with at least one curved roller and at least one tension spring for opening and closing the gripper arms. The curved roller is preferably arranged in an axial manner to the gripper arms. Two pivotable mounted rings are provided at the axis of the curved roller, wherein said rings operate in each case one lever per gripper arm, wherein the levers are provided in each case at the axes of rotation of the gripper arms. 
     Since further features of the gripper head were already described in great detail with respect to the above-mentioned gripper unit, a separate description is hence not necessary. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features and advantages of the present invention shall now be described in greater detail according to the accompanying figures in the following detailed description. The dimensions of the individual elements to each other do not always correspond with the real dimensions since some forms are shown simplified and other forms are shown enlarged with respect to other elements for the sake of clarity. 
         FIG. 1  shows a schematic view of a gripper head; 
         FIG. 2  shows a further schematic view of the gripper head; 
         FIG. 3  shows a gripper unit in a front view; 
         FIG. 4  shows a gripper unit in a rear view; 
         FIG. 5  shows the shift of a gripper unit in two transporting directions and 
         FIG. 6  shows the individual components of the gripper head in an exploded view. 
     
    
    
     DETAILED DESCRIPTION 
     Same elements refer to same reference numbers throughout the various figures. Furthermore, only reference numbers which are necessary for the description of the respective figure are shown in the various figures for the sake of clarity. The shown embodiments are only examples of how the method according to the invention can be designed and shall not be regarded as limiting the invention. 
       FIG. 1  and  FIG. 2  show in each case a schematic view of a gripper head  12  for supporting and transporting articles, particularly bottles (not shown), wherein the bottles are preferably gripped by gripper arms  20   a ,  20   b  below the enlargement at the bottle neck. Likewise it is possible that the gripping is carried out at the so called body of the container. This can be carried out, for instance, by using modified fastening elements. 
     The gripper head  12  has the two gripper arms  20   a ,  20   b , wherein the opening  21  formed by the two gripper arms  20   a ,  20   b  is adjustable in a variable manner. This adjustment is preferably carried out by a curved roller  30 , which is attached at pivotable rings  32   a ,  32   b  via two levers  34   a  and  34   b . The pivotable rings  32   a ,  32   b  are directly connected with the gripper arms  20   a ,  20   b  via pivotal axis X and cause the opening of said gripper arms  20   a ,  20   b . The closing of the gripper arms  20   a ,  20   b  is carried out via a spring element  22  which is arranged between the gripper arms  20   a ,  20   b . The spring element  22  is preferably a tension spring and return spring respectively. The return spring can be replaced by other similar return elements, such as magnets or the like. 
     The opening mechanism for the gripper arms  20   a ,  20   b  is directly integrated at the gripper head according to the embodiment shown here. The opening mechanism is operated by a curved roller  30  which is arranged in an axial manner to the gripper arms  20   a ,  20   b . At the axis of the curved roller  30  two pivotable mounted rings  32   a ,  32   b  are provided, which in each case operate the respective lever  34   a ,  34   b  of the left and right gripper arms  20   a ,  20   b . Preferably, the pivotable mounted rings  32   a ,  32   b  are arranged at the axes of rotation X, X′ of the gripper arms  20   a ,  20   b.    
     For easily adjusting the position and for safety in the event of malfunction, the opening mechanism, which includes the curved roller  30 , the levers  34   a ,  34   b  and the pivotable rings  32   a ,  32   b , is provided with fasteners  36 ,  37  which are shown in  FIG. 3 , wherein said fasteners  36 ,  37  are provided in a cone-shaped manner between the respective axes of rotation X, X′ of the gripper arms  20   a ,  20   b  and the levers  34   a ,  34   b . Thus, the position of the curved roller  30  to the gripper arms  20   a ,  20   b  can be adjusted by correct positioned clamping of the cones at the levers  34   a ,  34   b  and at the fastener  36  when installing the gripper head  12 . In the event of malfunction, particularly when it comes to a collision of the transported articles, a mechanic shift of the gripper head is carried out due to the high speeds, and the tapered connection slides through. However, the position can be easily adjusted again due to the chosen construction. 
     Such as clearly shown in  FIGS. 1 and 2 , the levers  34   a ,  34   b  are arranged in a crosswise manner seen from the gripper arms  20   a ,  20   b . When the curved roller  30  moves in direction of the clamping center and in direction of the opening  21  respectively, it hence causes an opening of the gripper arms  20   a ,  20   b . A spring element  22  arranged between the gripper arms  20   a ,  20   b  provides the closing of the gripper arms  20   a ,  20   b  due to the tension of the spring and thus an adjustment onto the articles to be transported, wherein said articles are particularly blown containers. By means of this mechanism, the articles to be transported can be supported in a firm and secure manner. 
     Furthermore, the gripper head  12  is provided with a dovetail section  51 , which is arranged in a vertical manner, with a limit stop  54  for height adjustment and easy replacement of the gripper head  12 . The limit stop  54  can be particularly an adjusting screw with which the axial run-out of the gripper head  12  can be adjusted. The adjusted position of the limit stop  54  can be secured against rotation by a laterally arranged clamping screw. 
     The interaction of the dovetail section  51  with a corresponding counter piece  52 , which forms a dovetail groove, and the forming of a respective dovetail joint  50  are shown in  FIGS. 4 to 6 . 
       FIG. 3  shows the individual components of the gripper head  12  in an exploded view. The figure particularly shows the construction of the levers  34   a ,  34   b , the construction of the pivotable rings  32   a ,  32   b  which are connected with said levers  34   a ,  34   b , wherein said levers  34   a ,  34   b  ensure the transmission of the shift movement onto the gripper arms  20   a ,  20   b , and the determination of the pivoting rings  32   a ,  32   b  at the axes of rotation X, X′ of the gripper arms  20   a ,  20   b , wherein said axes of rotation comprises at least one screw  33   a  and two washers  33   b  in the embodiment shown here. Other possibilities for opening and closing the gripper arms  20   a ,  20   b  known to a person skilled in the art shall also be covered by the invention. 
     Furthermore, the cone-shaped fastener  36 ,  37  is exposed, which serves on the one hand to adjust the position of the levers easily and on the other hand provides security in the event of malfunction. 
       FIG. 4 ,  FIG. 5  and  FIG. 6  show in each case a gripper unit  10  which includes a gripper head  12 , a shifting unit  14  and a fastener  16 . 
     The gripper head  12  is provided with a dovetail section  51  which is arranged in a vertical manner and wherein said dovetail section  51  grips into a corresponding counter piece  52  defining a dovetail groove at the shifting unit  14  and thus forms a dovetail joint  50 . The corresponding counter piece  52  is provided with a clamp  60 , for example with a clamping screw. When said clamp  60  is released, then the height of the gripper head  12  can be shifted easily. When the clamp is tightened again, then the position of the gripper head is determined contrary, i.e with respect to, to the shifting unit and thus also determined spatially contrary to the transport system. 
     Furthermore, the whole gripper head  12  can be removed and replaced by another gripper head  12 , which is likewise provided with a similar dovetail section  51 , wherein said dovetail section  51  grips in a positive manner into the corresponding counter piece  2  of the shifting unit  14 . Thus, a simple exchange of the gripper head  12  is possible. 
     Hence, a defect gripper head  12  can be easily replaced or another gripper head  12  can be installed, which is adjusted onto the articles to be processed, if necessary. This is necessary, for example, in the event of supporting and transporting articles with a significantly different diameter so that the usage of another gripper head  12  is mandatory. 
     The fastener  16  serves as a connection element between the unit, which includes the gripper head  12  and the shifting unit  14 , and the transport system, wherein said transport system is an infeed and discharge starwheel respectively or the like, for example. The fastener  16  is mounted on the transport system with a rotary degree of freedom, which enables an additional rotational movement relative to the transport system besides the linear movement of the gripper head. 
       FIG. 6  clarifies the possibilities of the vertical possibility of adjustment A via a dovetail joint  50 , which includes the dovetail section  51  at the gripper head  12  and the respective counter piece  52  defining a dovetail groove at the shifting unit  14 , as well as a horizontal possibility of adjustment B between the shifting unit  14  and the fastener  16 , which influences the distance between gripper head and transport system. 
     The shifting unit  14  is arranged between the gripper head  12  and the fastener  16  in the embodiment shown. The shifting unit  14  is constructed such that a linear movement or shifting movement is possible in horizontal direction. The shifting unit  14  is preferably provided with a guide rail  70 . The fastener  16  is provided with corresponding sliders  72 , which engage into the guide rail  70  and are shiftable therein. 
     The linear movement of the shifting unit  14 , that is the shifting movement in particular, is supported particularly by a tension spring  74 , which enables the simplified retraction into a first original position. The tension spring  74  is arranged at the rotating fastener  16  with its rear suspension point  76 . The front suspension point  75  of the tension spring  74  is arranged at the shifting unit  14 . 
     When the shifting unit  14  is arranged, for example, at a rotary transfer starwheel, then the tension spring  74  supports in addition the centrifugal force which impacts onto the shifting unit  14  and which is caused by the rotation of the starwheel. 
     In particular, the distance between gripper head  12  and transport system can be varied by the second moving component. This is necessary in the event of preventing a collision when articles are transferred from one transfer starwheel to another transfer starwheel, or to a processing unit. For this purpose, rollers  80  can be provided for example at the shifting unit  14  and/or at the fastener  16 , wherein said rollers  80  serve for guiding the gripper unit in special transport guide rails and thus always exactly determine the horizontal distance between gripper head  12  and transfer system. 
     The invention has been described with reference to preferred embodiments. It is also conceivable to a person skilled in the art, however, to make changes and modifications to the invention without leaving the scope of protection of the appended claims. 
     LIST OF REFERENCE NUMBERS 
     
         
           10  gripper unit 
           12  gripper head 
           14  shifting unit 
           16  fastening means 
           20   a/b  gripper arms 
           21  Opening 
           22  spring element 
           30  curved roller 
           32   a/b  pivotable ring 
           33   a  Screw 
           33   b  Washer 
           33   c  screw nut 
           34   a/b  Levers 
           36  cone-shaped fastener 
           37  cone-shaped fastener 
           50  dovetail joint 
           51  dovetail groove 
           52  corresponding counter piece to the dovetail groove 
           54  limit stop 
           60  Clamping 
           70  guide rail 
           72  Slider 
           74  tension spring 
           75  front suspension point 
           76  rear suspension point 
           80  Roller 
         A vertical possibility of adjustment 
         B horizontal possibility of adjustment 
         X/X′ axes of rotation