Abstract:
A servo adjustable gripper device for gripping and transporting at least two objects such as boxes includes a frame and at least two gripper assemblies connected with carriages slidably connected with the frame. The gripper device further includes a robotic arm which controls further movement and placement of the boxes on a pallet. The position of the gripper assemblies on the frame is adjustable to provide equal lifting force for a variety of differently sized boxes or for different numbers of boxes.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     In a manufacturing facility, items are packaged into boxes which are grouped in a linear configuration and positioned or aligned, such as on a conveyor with an end stop and reference clamp to pre-position the boxes. The aligned boxes are then lifted from the conveyor and placed onto pallets for shipment. Recent advances use fixed vacuum suction devices to lift the boxes from the conveyor and a robotic arm to transfer the vacuum suction devices and the associated boxes to a pallet.  
         [0002]     The present invention was developed in order to provide an adjustable gripping assembly in which the gripping devices may be adjusted depending on the size and number of boxes to quickly and efficiently transfer aligned boxes to a pallet.  
       BRIEF DESCRIPTION OF THE PRIOR ART  
       [0003]     Robotic transfer devices for removing articles from a conveyor are well-known in the prior art. In the de Koning U.S. Patent Publication No. 2003-0234157 A1, there is disclosed a robotic loading cell for molded utensils in which a mechanical gripper device is used to grip molded utensils from a conveyor and a robotic transfer mechanism is used to transfer the gripped utensils to a packaging assembly. Also known in the art are vacuum gripping assemblies which use suction to remove articles from a conveyor for packaging the articles. Such assemblies are disclosed in the de Koning et al U.S. Pat. No. 5,943,842.  
         [0004]     While the prior devices operate satisfactorily for their intended use, there are no gripper assemblies capable of simultaneously transferring a plurality of different sized boxes or objects from a conveyor or other alignment device to a pallet for shipping. The present invention was developed to fill this void by providing a servo adjustable gripper device which can accommodate boxes or objects of different sizes and numbers to efficiently load the boxes on a pallet for shipping.  
       SUMMARY OF THE INVENTION  
       [0005]     Accordingly, the present invention relates to a servo adjustable gripper device for transporting aligned boxes which includes an elongated frame having a plurality of carriages slidably connected therewith for longitudinal movement. A screw assembly is connected between the frame and the carriages and a servo motor is operated to turn the screw. Selective operation of the servo motor displaces the carriages along the frame to positions determined by the size and number of boxes to be transported. At least one gripping assembly is connected with each carriage. When the carriages are adjusted along the frame and the frame is positioned above the boxes, the gripping assemblies are actuated to simultaneously grip the boxes. The frame can then be moved to deposit the boxes on a pallet for shipping or to another location.  
         [0006]     Preferably, the frame is moved by a robotic arm under control of a controller. The controller also controls the servo motor to position the carriages and to operate the gripping assemblies so that the entire transport process is automated.  
         [0007]     The gripping assemblies comprise vacuum or mechanical grippers depending on the objects to be transported. Preferably, the assemblies comprise an array of grippers to provide more gripping force or to simultaneously transport more objects.  
         [0008]     According to a preferred embodiment of the invention, the carriages at the opposite ends of the frame include a single set of gripping assemblies and the remaining carriages have two parallel sets of gripping assemblies. With this arrangement, a set of gripping assemblies can be positioned adjacent to the opposite edges of an object to be transported.  
         [0009]     According to another object of the invention, the frame includes a plurality of pallet grasping arms which are operable by the controller to move a pallet to a desired location. 
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0010]     Other objects and advantages of the invention will become apparent from a study of the following specification when viewed in the light of the accompanying drawings, in which:  
         [0011]      FIG. 1  is a perspective view of the servo adjustable gripper device according to the invention;  
         [0012]      FIG. 2  is a front plan view of the gripper device according to a preferred embodiment of the invention;  
         [0013]      FIG. 3  is a top plan view of the gripper device of  FIG. 2 ;  
         [0014]      FIG. 4  is right side plan view of the gripper of  FIG. 2 ;  
         [0015]      FIG. 5  is a front detailed view of the carriage assemblies of the servo adjustable gripper device according to the invention;  
         [0016]      FIG. 6  is a top detailed view of the drive mechanism for the carriage assemblies of  FIG. 5 ;  
         [0017]      FIG. 7  is a left side view of the carriage and drive mechanism of  FIGS. 5 and 6 ;  
         [0018]      FIG. 8  is a right side view of the carriage and drive mechanism of  FIGS. 5 and 6 ;  
         [0019]      FIG. 9  is a schematic view of the arrangement of carriages for simultaneously transporting three boxes of the same size and configuration;  
         [0020]      FIG. 10  is a schematic view of an alternate arrangement of carriages for simultaneously transporting four boxes of the same size and configuration;  
         [0021]      FIG. 11  is a schematic view of the arrangement of carriages of  FIG. 10  used for simultaneously transporting four boxes of the same size and configuration but larger than the boxes of  FIG. 10 ;  
         [0022]      FIG. 12  is a partial perspective view of the servo adjustable gripper device showing the pallet grasping arms in detail;  
         [0023]      FIG. 13  is a front plan view of the gripper device of  FIG. 12 ;  
         [0024]      FIGS. 14 and 15  are top and right side plan views, respectively, of the gripper device of  FIGS. 12 and 13 ; and  
         [0025]      FIG. 16  is a plan view of a mechanical gripper according to the invention.  
     
    
     DETAILED DESCRIPTION  
       [0026]     Referring to  FIG. 1 , the servo adjustable gripper device  2  according to the invention will be described. The device is used to grip a plurality of objects such as boxes  4  and deposit them onto a pallet  6  for shipment. The boxes originate from a conveyor or other device in which a plurality of boxes of packaged articles are aligned in end to end fashion and are transported by the gripper device for placement on the pallet. More particularly, the gripper device includes a frame  8  which is connected with a robotic arm  10  and a controller  12 . The controller controls the movement of the arm and operation of the gripper device to simultaneously transport the boxes.  
         [0027]     The details of the servo adjustable gripper device according to the invention are better shown in  FIGS. 2-4 . At the top of the frame is a swivel device  14  which is connected with the end of the robotic arm so that the frame can be rotated relative to the arm. The frame has a generally rectangular configuration and includes a pair of side plates  16 ,  18 , a pair of end plates  20 ,  22 , and a center plate  24 . A junction box  26  is arranged at one end of the frame and is electrically connected with the controller  12  for receiving control signals therefrom.  
         [0028]     A plurality of carriages  28  are slidably connected with the frame as will be discussed in greater detail below in connection with  FIGS. 5-8 . The carriages have at least one gripping assembly  30  connected therewith. Also connected with the frame are pallet grasping arms  32  and pneumatic cylinders  34  for displacing the arms  32  under control of a pneumatic valve assembly  36  as will be described below with reference to  FIGS. 12-15 .  
         [0029]     Referring now to  FIGS. 5-8 , the slidable carriages  28  and gripping assemblies  30  will be described. In the embodiment shown in these figures, there are four carriages  28   a ,  28   b ,  28   c , and  28   d . Connected between the frame end plates  20 ,  22  and passing through the center plate  24  of the frame are parallel guide rails  38  which support the carriages  28   a - d . Between the guide rails  38  are provided two parallel lead screws  40  and  42  which are rotated by a servo motor  44  under control of the controller  12  via the junction box  26 . Referring to  FIG. 7 , a drive gear  46  is rotated by the servo motor  44 . An idler gear  48  transfers rotation of the drive gear to a first gear  50  which rotates the screw  40  and a second gear  52  which rotates the screw  42 . The first and second gears have different diameters so that the first gear  50  rotates the screw  40  at a first speed and the second gear  52  rotates the screw  42  at a second speed which is twice the first speed. Substituting different sized gears will alter the rotational speed of the screws.  
         [0030]     The first and second screws pass through couplings  54  in the frame center plate  24 . The portions of the screws on opposite sides of the plate are threaded in opposite directions. That is, the left portion of the screw  40  is threaded in a first direction and the right portion of the screw on the opposite side of the center plate is threaded in an opposite direction. The same applies for the screw  42 .  
         [0031]     Each carriage includes a nut  56   a ,  56   b ,  56   c ,  56   d  which is threadably connected with one of the screws. More particularly, the nut  56   a  connects the carriage  28   a  with the left portion of the screw  42  and the nut  56   d  connects the carriage  28   d  with the right portion of the screw  42 . The nut  56   b  connects the carriage  28   b  with the left portion of the screw  40  and the nut  56   c  connects the carriage  28   c  with the right portion of the screw  42 . As the screw  40  rotates in a first direction, the carriages  28   b  and  28   c  are drawn together and when the screw rotates in the opposite direction, the carriages  28   b  and  28   c  are pushed away from each other. Similarly, as the screw  42  rotates in a first direction, the carriages  28   a  and  28   d  are drawn toward each other and when the screw rotates in the opposite direction, the carriages  28   a  and  28   d  are pushed away from each other. The carriages  28   a  and  28   d  move at twice the speed as the carriages  28   c  and  28   d  because of the different sizes of the drive gears  52  and  50 .  
         [0032]     Connected with each carriage  28  is at least one set of gripping assemblies including an array of gripping devices. In  FIGS. 1-15 , the gripping devices are vacuum devices  58  which utilize suction to grip the top surface of a box. The suction is provided by vacuum supplies  60  mounted on the frame. As shown in  FIG. 8 , three vacuum devices are provided in alignment for each set of gripping assemblies although any number of devices may provided. In lieu of vacuum devices, mechanical gripper devices may be provided where articles are to be transported instead of boxes.  FIG. 16  shows a mechanical gripper device  62  which includes gripper fingers  64  which are displaced between gripping and released positions by a servo motor  66 .  
         [0033]     As shown in  FIGS. 4 and 5 , the carriages  28   a  and  28   d  at opposite ends of the frame  8  include a single set of gripping assemblies whereas the carriages  28   b  and  28   c  include two sets of gripping assemblies. This enables gripping assemblies to be positioned at the edges of the boxes. As shown in  FIG. 5 , the single set of gripping assemblies from the carriage  28   a  and one set of gripping assemblies from the carriage  28   b  are positioned at opposite edges of the left most box  4 , the other set of gripping assemblies from the carriage  28   b  and one set from the carriage  28   c  are at opposite edges of the center box, and the other set of gripping assemblies from the carriage  28   c  and the single set of gripping assemblies from the carriage  28   d  are positioned at opposite edges of the right box. This arrangement is more clearly shown in  FIG. 9 .  
         [0034]      FIGS. 10 and 11  show an alternate arrangement of carriages for transporting an even number of boxes. A center carriage  28   e  is provided which is fixed to the frame. Unlike the carriages  28   a - d , the fixed center carriage  28   e  does not move along the frame. The fixed carriage includes two sets of gripping assemblies which are positioned at the edges of adjoining center boxes as shown. The remaining carriages are positioned as in the embodiment of  FIGS. 5 and 9  so that gripping assemblies are provided at the opposite edge of each box to be transported.  
         [0035]     In  FIG. 11 , the same servo adjustable gripper device as shown in  FIG. 10  is provided, except that the device is being used to transport larger (wider) boxes than are being transported in  FIG. 10 . The larger boxes are accommodated by positioning the slidable carriages as necessary so that the gripping assemblies are arranged adjacent the end edges of the boxes.  
         [0036]     With the present invention, all the operator of the servo adjustable gripper device must do is enter into the controller the number and dimension of the boxes to be transported. These entries are used by the controller to activate the servo motor  44  to turn the screws  40 ,  42  to properly position the carriages in accordance with the number and size of the boxes. If only two boxes are to be transported the outermost carriages  28   a  and  28   d  and the outermost gripping assemblies of the inner slidable carriages  28   b  and  28   c  would not be used. Thus, the adjustable gripper of the invention is extremely versatile and efficient for transporting boxes of articles from a loading conveyor to a pallet or other storage device. By entering the coordinates of the origin and destination into the controller, the robotic arm automatically transports the boxes as required. This allows a plurality of boxes to be efficiently transported simultaneously.  
         [0037]     Turning now to  FIGS. 12-15 , the pallet grasping arm feature of the invention will be described. Four pallet grasping arms  32  are pivotally connected with the side walls of the frame  8 , two arms per side. The arms on opposite sides of the frame are connected via rotatable shafts  68 . Pneumatic cylinders  34  on one side of the frame have plungers  70  which are connected with intermediate portions of the arms  32 . Operation of the cylinders by the pneumatic valve assembly  36  displaces the plungers to pivot the arms  32  up and down relative to the frame. Pivotal movement of the arms enables the end portions thereof to engage a pallet for transporting the same. A pallet stabilizer arm  72  is pivotally connected with the frame and pivoted by a pneumatic cylinder  74  under control of the pneumatic valve assembly  36  which is in turn operated by the controller. The stabilizer arm helps to steady the pallet during transport.  
         [0038]     While the preferred forms and embodiments of the invention have been illustrated and described, it will be apparent to those of ordinary skill in the art that various changes and modifications may be made without deviating from the inventive concepts set forth above.