Patent Document

BACKGROUND OF THE INVENTION  
         [0001]    This invention relates to the field of automated palletizing of cased goods.  
           [0002]    In an automated palletizing machine, called palletizers in the trade, cases of goods are received from a production line on an infeed conveyor. The cases of goods can be, for example, aluminum cans filled with beverages and wrapped in cardboard boxes, plastic water bottles shrink-wrapped together, or any other case or bundle. The cases of goods can be any product packaged in a similar manner or shape as these examples that is ready to be further packaged on a pallet. The palletizer groups the cases in layers, then successive layers are stacked on top of one another to form a load. The load of cases in turn can be stacked on top of a base, such as a pallet, that facilitates movement of the load by machine, such as by a forklift. The palletizer arranges the cases into layers and stacks them at a rapid pace—a pace equaling the speed at which the cases are received from the infeed conveyor.  
           [0003]    For stability, the layers of cases can be arranged into a pattern. The patterns of adjacent layers may be alternated so that the load of cases is well supported, secure, and balanced. In order to arrange the cases in a layer into a desired pattern appropriate for stacking on top of the previous layer, it may be necessary to turn some of the cases as the layer is formed so that certain cases have a different orientation relative to the layer than others.  
           [0004]    During the process of case turning, the cases can be damaged. Typically a prior art turning device comes into contact with a portion of the case while the case is traveling forward in a direction of case travel on the conveyor system of the palletizer. The turning device pushes on one end of the case and temporarily slows the forward movement of the one end of the case while the other end of the case continues to move forward at a greater speed than the one end. The difference in the forward speed of each end of the case causes the case to rotate. The contact of the turning device with the cases during case turning can generate significant forces when the cases are traveling at high speeds. As a result, the packaging of the case, or even the product itself, can be damaged during case turning. Also, case turning can cause the palletizer to operate unreliably. The case turning can cause the packaging of the case to come loose and jam the machinery of the palletizer. The case turning machinery itself can wear more quickly than other components of the palletizer because of its harsh contact with the cases. As a result of its more rapid wear, the case turning machinery can necessitate more frequent maintenance and down time of the palletizer. In addition, to operate effectively the case turning procedure can require the palletizer to operate at a lower case per minute speed than it might otherwise operate if the case turning did not occur.  
           [0005]    Thus, benefit can be had from case turning that operates reliably and quickly, while causing less damage to the cases, so that losses from damaged cases can be minimized and so that the palletizer can be run at a more rapid pace and more reliably. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    FIGS.  1 A- 1 D schematically illustrate a case turning device which, according to one aspect of the invention, is turning more than one case simultaneously.  
         [0007]    [0007]FIG. 2 schematically illustrates a palletizer, and various sections of a conveyor system including an accumulator conveyor and an infeed conveyor.  
         [0008]    [0008]FIG. 3 is a front view of one embodiment of a turning device employing four pin turners which are each capable of movement in the direction of case travel to reduce the net speed of collisions with the cases.  
         [0009]    [0009]FIG. 4 is a side view of the turning device of FIG. 3.  
         [0010]    [0010]FIG. 5 is a top view of the turning device of FIG. 3. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0011]    For convenience, similar elements are designated throughout the drawing figures with the same reference numerals.  
         [0012]    The invention provides various methods of improving the turning of cases on a palletizer and palletizers capable of carrying out the various methods. In one aspect of the invention, cases may be turned simultaneously in groups through a single turning operation, rather than individually, in order to reduce the number of collisions that are necessary to turn the cases and form the desired pattern. For example, if contiguous first and second cases are to be oriented 90 degrees relative to the direction of case travel on the palletizer, then the two cases can be turned simultaneously in the same turning operation by the turning device contacting the first case only. The first case is turned by the contact with the turning device, and the second case is turned simultaneously due to its contact with the first case.  
         [0013]    FIGS.  1 A- 1 D illustrate this procedure. In FIG. 1A, a first case A and a second case B are moving in the direction of case travel on a conveyor system  100  towards a turning device  200 . Case A and case B are oriented so that their longitudinal dimension is perpendicular to the direction of case travel. In this example, the first case A and the second case B are touching one another, but it is possible for there to be initially some gap between the cases. In FIG. 1B, the turning device  200  has collided with a first end of the first case A causing the speed of the first end of case A in the direction of case travel to be reduced. A second end of case A is permitted to continue its movement in the direction of case travel at a speed greater than the first end, thus causing the case A to turn about an axis normal to the direction of case travel. Because of its contact with the case A, case B also begins to turn. In FIG. 1C case A has completed most of its turn and case B has completed most of its turn. In FIG. 1D, case A is no longer in contact with the turning device  200 , and case A and case B have each completed their simultaneous turn and have been reoriented 90 degrees relative to the direction of case travel.  
         [0014]    As previously stated, the cases are turned by a turning device  200 . The turning device  200  could be an arm which moves laterally relative to the direction of case travel from a first lateral position, or rest position, outside of the path of the cases to a second lateral position in the path of the cases to collide with the cases. Such an arrangement is shown, for example, in FIG. 2 a  of U.S. Pat. No. 6,499,583. Or, as illustrated in the drawings herein, the turning device  200  may comprise a rod  210  which moves vertically from a first vertical position, or rest position, out of the path of the cases to a second vertical position where the turning device will collide with the cases. FIG. 1A shows the rod  210  in the first vertical position where it will not collide with the cases. FIGS.  1 B- 1 D show the rod  210  in its second vertical position where it will collide with the cases. This type of turning device is called a pin turner in the trade. The turning device  200  may comprise other arrangements that will be recognizable to those of skill in the art.  
         [0015]    The turning device  200  also comprises an actuating means for moving the turning device from its rest position to a position where it will collide with the cases. The actuating means may comprise a pneumatic cylinder, a linear motor, a lead screw, a rack and pinion, a belt and pulley system, or any of a number of other known and functionally comparable actuating systems. In the drawings herein, a pneumatic cylinder  220  is provided as the actuating means.  
         [0016]    According to this aspect of the invention, because multiple cases are turned together, the number of collisions between the turning device and the cases is reduced. The number of collisions is less than the total number of cases that are turned. While only the simultaneous turning of two cases has been described and illustrated, more than two cases may also be turned simultaneously in a similar manner. Of course, the same apparatus capable of turning multiple cases together may also be used to turn individual cases independently, or may also be used to turn selective multiple cases together and selective individual cases independently, as desired.  
         [0017]    In another aspect of the invention, the speed at which the cases move on the conveyor system of the palletizing machine can be reduced as the cases enter the portion of the conveyor system where the cases are turned. In one embodiment of a palletizer illustrated in FIG. 2, the cases are received from an infeed conveyor  110  at a first speed, measured in cases per minute. The cases on the infeed conveyor may be stacked back-to-back with all of the cases touching. The speed of the cases is next increased to a second speed greater than the first speed by a spacing conveyor  120  to produce a gap for counting the number of cases, and to feed the cases onto a line divider  130  which moves the cases into various lateral paths relative to their direction of travel. Because the cases may be turned simultaneously with one case touching one another, the gap between the cases does not necessarily need to be maintained in the turning area  140  of the palletizer. Thus, the speed of the conveyors in the turning area  140  can be decreased to a third speed that is less than the second speed, and greater than or equal to the first speed. Multiple cases will then arrive at the turning device  200  approximately back-to-back and touching one another—ready to be turned simultaneously. Because of the reduction in the speed of the cases in the turning area  140  of the palletizer, the collision speed of the cases with the turning device  200  is reduced and the forces generated during the collision are reduced, resulting in avoidance of some damage to the cases.  
         [0018]    Alternatively, if the speed of the cases is not slowed adequately so that the cases arrive at the turning device  200  back-to-back, a retractable stop  141  can be provided in the conveyor system  100  before the turning device  200  in order to group several cases together to be turned simultaneously. The stop  141  can selectively hold a case or group of cases stationary on the conveyor system  100  until the cases to be turned simultaneously have been grouped together and are touching one another. Then the stop  141  is retracted and the group of cases moves forward again in the direction of case travel toward the turning device  200 .  
         [0019]    If the groups of cases to be turned simultaneously arrive at the turning device already touching one another, then there would be no need for a stop to temporarily hold the cases stationary for grouping.  
         [0020]    In order for the reduction in speed of the cases in the turning area  140  to consistently position the cases in close proximity to one another without using any stops  141 , the infeed conveyor  110  must deliver cases continuously to the palletizer. In order to ensure that the infeed conveyor  110  delivers cases continuously to the palletizer, an accumulator conveyor  150  may be provided with a retractable stop  151 . The retractable stop  151  will temporarily hold the cases until enough cases are accumulated in the accumulator conveyor  150  to make up an entire layer of cases for the load. The retractable stop  151  will then be retracted and permit the cases to move forward in the direction of case travel to the infeed conveyor  110  with each of the cases being back-to-back. It is also possible to simply turn off the accumulator conveyor  150  and let cases collect on this conveyor until enough cases have been accumulated to make up an entire layer of cases for the load. Then the accumulator conveyor  150  is turned back on to convey the cases forward in the direction of case travel to the infeed conveyor  110  with each of the cases being back-to-back.  
         [0021]    In another aspect of the invention, the turning device  200  may be provided with a component of movement in the direction of case travel. When the cases collide with the turning device  200 , the turning device can be moved forward in the direction of case travel to reduce the net speed of the collision. Because of the reduction in the net speed of the collision with the turning device  200 , collision forces on the cases are reduced and some damage to the cases can be avoided.  
         [0022]    FIGS.  1 A- 1 D also illustrate this movement of the turning device  200  in the direction of case travel. In FIG. 1A the turning device is situated in its default horizontal position. In FIG. 1B, the turning device  200  is colliding with case A and the turning device is moving in the direction of case travel to reduce the net collision speed.  
         [0023]    An actuation means is provided for moving the turning device  200  in the direction of case travel. The actuating means may comprise a pneumatic cylinder, a linear motor, a lead screw, a rack and pinion, a belt and pulley system, or any of a number of other known and functionally comparable systems. In the drawings herein, a pneumatic cylinder  230  is provided as the actuating means for moving the turning device in the direction of case travel. Before the turning device  200  collides with the case, the actuating means can actuate the turning device to move the turning device in the direction of case travel, thus reducing the net speed of the collision.  
         [0024]    As used herein, the description of a turning device moving in a direction of case travel will be met not only when the turning device is moving substantially parallel to the movement of the cases, but also when the turning device is moving in a direction diagonal to the movement of the cases, or is moving in some other direction, so long as the turning device has at least a component of movement in the direction of case travel.  
         [0025]    FIGS.  3 - 5  illustrate one embodiment of a case turning device  200  with a component of movement in the direction of case travel. In the embodiment of FIGS.  3 - 5 , the turning device comprises a rod  210  that is actuated between a first vertical position and a second vertical position by a pneumatic cylinder  220 . The rod may include a plastic roller  211  on the end thereof, or some type of a cushion, for softening the impact with the cases. The subassembly of the rod  210  and the pneumatic cylinder  220  are supported for sliding movement in the direction of case travel on a frame system  240 . To move the turning device  200  between first and second horizontal positions in the direction of case travel, pneumatic cylinder  230  actuates the subassembly of the rod  210  and the pneumatic cylinder  220 .  
         [0026]    The actuating means for moving the turning device  200  in the direction of case travel may actively actuate, for example by a pneumatic power system coupled to a pneumatic cylinder, or may passively actuate, for example by a mechanical or air spring. Passive actuation would occur with an air spring when a case collides with the rod  210  and the fluid within the cylinder  230  is compressed as the rod  210  moves in the direction of case travel under force of the case. The air spring could be constructed by closing the end of the cylinder  230  so that movement of the rod  210  toward the cylinder  230  compresses the fluid in the cylinder. The cylinder might also include a damper for damping the movement of the rod  210 .  
         [0027]    [0027]FIG. 6A illustrates one version of an actuator for moving the turning device  200  in the direction of case travel. In this version the cylinder  230  is double-actuated with one port A positioned on the rod side of the piston  232   a  and another port B positioned on the other side of the piston  232   b . Port B is connected to a source of constant pressure fluid P 2 , such as compressed air. Port A is connected to a valve  250 . In its de-energized, or rightward position illustrated in FIG. 6A, valve  250  connects port A to another source of constant pressure fluid P 1 . The pressure of the fluids P 1  and P 2  at ports A and B can be selected so that the pressure differential on each side of the piston  232 , and the area differential resulting from having rod  231  attached to the rod side of the piston  232   a , cause the piston to be near a force equilibrium with the net force pushing the piston to the left end of cylinder  230  in FIG. 6A. Thus the rod  231  would extend out of cylinder  230  until the force of a case colliding with the turning device  200  pushes the rod  231  back into cylinder  230  and the piston  232  to the right end of cylinder  230 . Once the force of the case collision is removed, the rod  231  would be extended again from cylinder  230 . In order to manually extend rod  231  or to retain rod  231  in a fully extended position, valve  250  may be energized to move to its energized, or leftward position in FIG. 6A, so that port A is connected to the atmosphere ATM. In this case the pressure on the rod end of the piston  232   a  would be removed and the net force on the piston  232  would cause the piston to move to the left end of cylinder  230  in FIG. 6A and the rod  231  to extend. Dampers  251  can be used with port A and/or port B to control the flow of the fluid and affect the speed of rod  231 . One advantage of this version of an actuator is that it can handle a wide range of case weights and speeds.  
         [0028]    As used herein, the description of the turning device  200  moving in, or being propelled in the direction of case travel during collision with the cases is met i) when the turning device is actively actuated by moving the turning device with an active actuator independent of the occurrence of a collision with a case, or ii) when the turning device is moved in response to the collision with the turning device actuated by an actuating means which passively responds to the force of the collision, such as a spring.  
         [0029]    While reducing the impact forces, the slowing of the net collision speed through either the reduction in the speed of the cases in the turning area  140  of the palletizer, and/or through the movement of the turning device  200  in the direction of case travel during the collision can cause poor turns where all the cases are not consistently reoriented to the desired orientation. In order to prevent poor turns, it may be necessary to move the turning device  200  in the opposite direction of case travel throughout the case&#39;s turn or near the end of the turn. When the turning device  200  is moved in the opposite direction of case travel, the net speed between the cases and the turning device is increased. Of course, when the turning device  200  is provided with an actuation means that is used to move the turning device  200  in the direction of case travel during collisions with the cases, the same actuation means can also be used to move the turning device in the opposite direction of case travel near the end of a case&#39;s turn. FIGS.  1 A- 1 D also illustrate this procedure. In FIG. 1B, as was previously described, the turning device  200  has been moved the full extent of its travel in the direction of case travel in order to reduce the net collision speed with case A. In FIG. 1C, the actuation means has begun to move the turning device  200  in the opposite direction of case travel in order to increase the net speed of case A relative to the turning device. In FIG. 1D, the turning device has returned to its first horizontal position of FIG. 1A.  
         [0030]    [0030]FIG. 6B illustrates one version of an actuator for moving the turning device  200  both in the direction of case travel and opposite the direction of case travel. In FIG. 6B the cylinder  230  is double-actuated with a port A on the rod side of the piston  232   a  and another port B positioned on the other side of the piston  232   b . Port A is connected to valve  250 . In its de-energized, or rightward position illustrated in FIG. 6B, valve  250  connects port A to a source of constant pressure fluid P 1 , such as compressed air. Port B is connected to valve  252 . In its de-energized, or rightward position illustrated in FIG. 6B, valve  252  connects port B to the atmosphere ATM. With valves  250  and  252  each in their de-energized positions, there is pressurized fluid only on the rod side of the piston  232   a . Thus the piston  232  will be moved to the right end of cylinder  230  in FIG. 6B, and rod  231  will be retracted. If valve  252  is energized to move to its energized, or leftward position in FIG. 6B, then port B will also be connected to P 1 . In this case, with equal pressure on the rod side of the piston  232   a  and the other side of the piston  232   b , the area differential between  232   a  and  232   b  causes a force differential on piston  232  with the net force moving the piston to the left end of cylinder  230  and extending rod  231 . The piston  232  is near a force equilibrium such that the force of a case colliding with the turning device  200  will cause the piston  232  to move rightward in FIG. 6B and the rod  231  to retract.  
         [0031]    If valve  250  is now energized to move to its energized, or leftward position in FIG. 6B, then port A will be connected to ATM. Then the pressure on the rod side of the piston  232   a  will be removed and the piston  232  will be moved leftward in FIG. 6B and the rod  231  will extend. The extending rod  231  can move the turning device  200  in the opposite direction of case travel to increase the net speed between the turning device and the cases to correct poor turns. Dampers  251  may be used with port A and/or port B to control the flow of the fluid and affect the speed of rod  231 .  
         [0032]    Whether it is necessary to move the turning device  200  opposite the direction of case travel to assist with the turn is dependent upon the case speed and the case weight, among other factors. Slower moving cases and heavier cases may require this assistance, while faster moving cases and lighter cases may not.  
         [0033]    Although the invention has been described through a description of a particularly preferred arrangement of components, and through a description of a particular sequence of steps in a method, various alternative configurations, alternative steps, and alternative step sequences are also possible. Modifications to the preferred embodiments will be readily apparent to those skilled in the art without departing from the spirit and scope of the invention. Thus, the foregoing descriptions of the preferred embodiments are illustrative only and are not intended to limit scope of the invention to the preferred embodiments. The scope of the invention shall be defined by the appended claims.

Technology Category: b