Abstract:
A packaging machine is shown for individually wrapping objects, such as candies. The machine has a rotary hopper for selecting the objects to be wrapped, folding them and ejecting them precisely onto a delivery conveyor. A continuous wrapping film is laid over the objects on the delivery conveyor and the sides of the film are folded downwardly to partially wrap the objects. The objects are then gripped through the wrapping film by gripping fingers mounted on a second gripping conveyor. The gripping conveyor moves the objects along while the bottom edges of the wrapper are crimped, and the wrapper between the objects is then crimped and cut off. The gripping fingers then release the wrapped object.

Description:
FIELD OF THE INVENTION 
     This invention relates to packaging machines, and in particular, to machines for individually wrapping objects, such as candies. 
     BACKGROUND OF THE ART 
     Packaging machines have been produced in the past for wrapping individual articles, such as candies. The candies usually pass along a conveyor where a continuous strip of wrapping film is laid on top of the candies and folded transversely around the candies. The peripheral edges of the wrapper can be sealed together under the candies, if desired, and the wrapping film is then transversely sealed between the candies and cut off to produce the individually wrapped candies. 
     There are several difficulties with the prior art wrapping machines discussed above. One is that the candies are haphazardly placed on the conveyor resulting in breaking or cracking of the candies, and this causes jamming and clean-up problems, not to mention machine down time. Another difficulty is that the candies are not located uniformly on the conveyor, so it is difficult to determine where the transverse wrapper seals should be located between the candies. Another problem is that even if the candies are located uniformly on the conveyor, the candies are allowed to shift or move around while they are being wrapped, so the wrapper seals do not occur exactly where they should. This is particularly problematic for printed wrappers, since the printing must be precisely located on the product. 
     SUMMARY OF THE INVENTION 
     The present invention ensures that the objects to be wrapped are held and positively and timely placed on the conveyor, and that the wrapper seals are located precisely by using a gripping conveyor that grips successive objects to be wrapped through the wrapping film and holds the film in place relative to the objects while the film is being sealed and cut off. 
     According to one aspect of the invention, there is provided a wrapping machine for individually wrapping objects. The machine comprises a delivery conveyor including a plurality of longitudinally arranged stations. Each station is adapted to receive one object to be wrapped. Means are provided for moving the conveyor longitudinally. A film stand is provided for supplying wrapping film longitudinally along the moving delivery conveyor in contact with the objects to be wrapped. The film has longitudinal peripheral edge portions that extent laterally and are sufficiently wide to wrap around the objects to be wrapped. A folder is mounted on the delivery conveyor and has side arms for folding the film edge portions along side the objects to partially wrap the objects. A gripping conveyor is located adjacent to the delivery conveyor to receive the partially wrap objects. The gripping conveyor includes a plurality of clamping devices spaced-apart longitudinally equidistantly with the delivery conveyor stations. Means are provided for moving the gripping conveyor and thus the clamping devices longitudinally in synchronization with the delivery conveyor. The clamping devices include opposed gripping fingers. Actuation means are provided for causing the gripping fingers to close to grip the received partially wrapped objects through the wrapping film. Crimping means are located between the clamping devices for crimping closed and cutting off the wrapping film between the wrapped objects. Also, the actuation means includes means for opening the gripping fingers to release the wrapped objects. 
     According to another aspect of the invention, there is provided a method of individually wrapping objects. The method comprises the steps of providing a moving conveyor and placing the objects to be wrapped on the conveyor at equal intervals. A continuous strip of wrapping film is placed in contact with the objects to be wrapped and the longitudinal edges of the film are folded along side the objects to partially wrap the objects. The partially wrapped objects are gripped through the wrapping film and the gripped objects are pulled off the conveyor. The wrapping film is crimped around the objects to complete the wrapping of the objects. The wrapping film is cut off between the objects and the wrapped objects are released. 
     According to yet another aspect of the invention, there is provided apparatus for feeding objects uniformly to a conveyor of a wrapping machine. The apparatus comprises a hopper having a floor pan and an upright peripheral wall. The floor pan has an opening for passing objects therethrough to the conveyor. A selector plate is located adjacent to the floor pan and has a plurality of holes therethrough for loosely accommodating the objects. Means are provided for moving the selector plate to cause the objects to enter the holes and for causing the holes to be located selectively over the peripheral opening. A spring finger is mounted in the peripheral wall and extends to engage and retain an object in the selected hole located over the peripheral opening. A piston is located opposite a selected selector plate hole located over the peripheral opening. Also, timed actuator means are provided for actuating the piston to push the object past the spring finger and through the peripheral opening. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: 
     FIG. 1 is a front elevational view of a preferred embodiment of a wrapping machine according to the present invention; 
     FIG. 2 is a rear elevational view of the machine shown in FIG. 1; 
     FIG. 2A is a rear elevational view similar to FIG. 2, but showing the gripping conveyor tilted up for cleaning and access purposes; 
     FIG. 3 is a vertical sectional view through the gripping conveyor of the machine of FIGS. 1 and 2; 
     FIGS. 4A to  4 C are enlarged perspective views of the gripping finger assemblies used in the gripping conveyor of FIG. 3, showing the operation of the gripping fingers; 
     FIG. 5 is a rear elevational view, partly broken away of the gripping conveyor; 
     FIG. 6 is an enlarged perspective view of the folder used on the wrapping machine shown in FIG. 1; 
     FIG. 7 is a plan view that the hopper section used to select and deliver the objects to be wrapped to the deliver conveyor in the machine of FIG. 1; 
     FIG. 8 is an enlarged plan view of the portion of FIG. 7 indicated by chain dotted line  8 ; 
     FIG. 9 is a vertical sectional view taken along lines  9 — 9  of FIG. 8; and 
     FIG. 10 is a plan view similar to FIG.  8 ,but with the ejector wheel and its drive removed for the purposes of illustration. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring firstly to FIGS. 1 and 2, a preferred embodiment of a wrapping machine according to the present invention is generally indicated by reference numeral  10 . Wrapping machine  10  includes a table or base  12 , a magazine or hopper or input tray  14  for receiving objects to be wrapped in machine  10 . The objects can be food items, such as candies, or they could be any other objects that are desired to be wrapped individually. Preferably, however, the objects are generally uniform in size and relatively rigid or incompressible, although some resiliency in the objects would be tolerable as well. 
     Machine  10  also includes a delivery conveyor  16  for receiving the objects from input tray  14  and delivering same to a gripping conveyor  18 . A film stand  20  contains rolls of wrapping film  22 , one of which is led through a series of rollers  24  down to a folder  26 , as described in more detail below in connection with FIG.  6 . Folder  26  folds the longitudinal edges of film  22  downwardly over the objects on delivery conveyor  16  to partially wrap the objects. These partially wrapped objects are then fed into gripping conveyor  18 , where the objects are gripped through the wrapping film by clamping devices  28 . Gripping conveyor  18  then carries the objects and the wrapping film along through crimping wheels  30  where the longitudinal edges of the wrapping film are crimped and sealed together. Further crimping devices  32  and  34  (see FIG. 3) then transversely crimp and seal the wrapping film transversely between the objects being wrapped and also cut off the wrapping film to separate the wrapped objects, as will be described further below. Clamping devices  28  then open to release the wrapped objects. Machine  10  includes a drive motor  35 , which drives all of the conveyors and crimping wheels in machine  10 , also as will be described in further detail below. 
     Referring next, in particular, to FIGS. 3 to  5 , in addition to FIGS. 1 and 2, the gripping conveyor portion  33  of machine  10  will now be described in further detail. As seen best in FIGS. 3 and 5, delivery conveyor  16  delivers the objects to be wrapped, as indicated by dotted lines  36 , to gripping conveyor  18 . Delivery conveyor  16  is an endless, longitudinally movable belt in the form of a chain conveyor having a plurality of transverse, equi-spaced fingers or projections  38  mounted thereon. Projections  38  extend upwardly through a slot  40  (see FIG. 8) formed in an elongate table  42  mounted in machine base  12 . The spaces between projections  38  form longitudinally arranged stations, each station being adapted to receive one object  36  to be wrapped. Delivery conveyor  16  is moved or driven longitudinally by a sprocket  44  (see FIG. 1) mounted on a shaft  46 . Shaft  46  is driven by a drive chain  48  coupled to drive motor  35 . 
     Gripping conveyor  18  is located adjacent to delivery conveyor  16  to receive objects  36 , which are now partially wrapped. Referring again to FIG. 1, it will be recalled that the film  22  passes under folder  26  where the film edge portions are folded downwardly along side objects  36  to partially wrap the objects. Gripping conveyor  18  includes a plurality of clamping devices  28  spaced apart longitudinally equidistantly with the delivery conveyor stations or projections  38 . Gripping conveyor  18  is an endless belt in the form of a conveyor chain  49  upon which are mounted clamping devices  28 . Clamping devices  28  include guide blocks  50  which are attached to conveyor chain  49  and gripping fingers  52 ,  54  mounted in pairs in guide blocks  50  for transverse sliding movement therein. The gripping fingers  52  and  54  of each pair of gripping fingers  52 ,  54  include respective opposed jaws  56 ,  58  for gripping the partially wrapped objects  36  and holding same during the completion of the wrapping operation and severance of the wrapped objects. Jaws  56 ,  58  include U-shaped blocks having spaced-apart distal portions  60  and  62 . Distal portions  60 ,  62  on respective opposed jaws  56 ,  58  face each other, and these distal portions  60  and  62  are concave to help hold objects  36  that are round or oblong in shape. 
     Jaws  56  and  58  are located at one end of gripping fingers  52 ,  54 . The opposite ends of gripping fingers  52 ,  54  form cam end portions  64  and  66  that define cam followers. In fact, a transverse cam follower  68  is mounted in cam end portion  64 , and the end  70  (see FIG. 4 c ) of cam end portion  66  actually forms a cam follower. FIG. 4 c  is the same as FIG. 4 a  with portions of FIG. 4 a  removed to show more clearly cam follower end  70 . 
     Gripping fingers  52 ,  54  are spring biased into the closed position as indicated in FIG. 4 a  by springs  72  and  74 . Spring  72  extends between cap screws  76  and  78  mounted respectively in cam end portion  64  and guide block  50 . Similarly, spring  74  extends between cap screws  80  and  82  mounted respectively in guide block  50  and gripping finger  54 . It will be appreciated that other bias means or ways to attach springs  72  and  74  could be employed in clamping devices  28 , if desired. 
     Gripping fingers  52 ,  54  are actuated by a plurality of cams  84 ,  86  and  88 ,  90 , as seen best in FIGS. 3 to  5 . In between the cams, the jaws  56  and  58  are closed as indicated in FIG.  4 A. Cam  84  bears against cam follower  68  to cause gripping finger  52  to retract, and cam  86  bears against cam follower end  70  to cause gripping finger  54  to extend, thus opening jaws  56 ,  58  as indicated in FIG.  4 B. The open jaws are thus in a position to allow a partially wrapped object  36  to enter therebetween from delivery conveyor  16  as indicated at the left hand end of FIG.  3 . When object  36  is in a position to be grasped by jaws  56 ,  58 , cams  84 ,  86  allow the jaws to close and clamp onto object  36 . Similarly, at the right hand end of gripping conveyor  18  as indicated in FIG. 3, cams  88 ,  90  cause gripping fingers  52 ,  54  to separate releasing a wrapped object  37 . Cams  84 ,  86  and  88 ,  90  are adjustable longitudinally and transversely to adjust the opening and closing positions of clamping devices  28  and the width of opening of jaws  56  and  58 . 
     As seen best in FIG. 3, between the time the objects  36  are gripped or grasped by clamping devices  28  as actuated by cams  84 ,  86  and the time the wrapped objects are released by the clamping devices  28  as actuated by cams  88 ,  90 , crimping wheels  30  crimp together and seal the adjacent lower peripheral edge portions  92  of wrapping film  22 . For this purpose, crimping wheels  30  can be heated, if required. Depending on the type of wrapping film used, in some applications only one set of crimping wheels  30  may be needed. After the lower peripheral edges  92  of the wrapping film are crimped together, a second pair of vertically arranged, opposed crimping and cut-off wheels  32 ,  34  transversely crimp and cut off the wrapping film between objects  36 . Actually, cut-off wheel  34  has a plurality of radial fingers with transverse cutting blades  98  mounted therein, and cut-off wheel  32  has a plurality of radial fingers with transverse end surfaces that form anvils for blades  98  to cut the wrapping film. Again, cut-off wheels  32 ,  34  can be heated, if required. The first set of horizontally arranged, opposed crimped wheels  30  and the second set of vertically arranged, opposed cut-off wheels  32 ,  34  form crimping means located between clamping devices  28  for crimping closed and cutting off the wrapping film  22  between the wrapped objects  36 . 
     Referring again to FIGS. 1 and 2, it will be seen that a chain and sprocket drive  100  is used to drive cut-off wheels  32 ,  34  and gripping conveyor  18 . However, a gear train drive could be used as well, as will be appreciated by those skilled in the art. Similarly, a gear train drive  102  is used to drive crimp wheels  30 , but another type of drive could be used for this purpose as well. Gripping conveyor  18 , crimping wheels  30  and cut-off wheels  32 ,  34  are all driven in synchronization with delivery conveyor  16 . However, position or speed adjustment between the various drives or components could be provided as well, as will be appreciated by those skilled in the art. 
     As indicated in FIG. 2A, gripping conveyor  18  swings up and out of the way as indicated by arrow  104  for cleaning purposes, or for helping to feed the wrapping film through the machine on start-up, and especially through crimping wheels  30  and cut-off wheels  32 ,  34 . 
     Referring next to FIG. 6, folder  26  will be described in further detail. Wrapping film  22  passes under folding wings  106 ,  108  to cause the longitudinal peripheral edge portions of wrapping film  22  to be folded downwardly along side objects  36  to partially wrap objects  36 . Film  22  is sufficiently wide that the longitudinal peripheral edge portions thereof wrap around and hang below objects  36  to be crimped by crimping wheels  30 , as discussed above. Folding wings or side arms  106 ,  108  are transversely adjustable to adjust this folding action. Additional adjustable guide plates  110 ,  112  assist in this folding and wrapping operation and cause the peripheral edges portions of wrapping film  22  to pass downwardly through slots  114 ,  116  to come together beneath object  36 . FIG. 6 shows a partially wrapped object  36  about to be grasped by a clamping device  28 , the remainder of gripping conveyor  28  being omitted from FIG. 6 for the purposes of clarity. 
     Referring next to FIGS. 7 to  10 , the hopper or input tray portion  14  of wrapping machine  10  will now be described in further detail. Input tray assembly  14  is used to deposit objects  36  onto delivery conveyor  16  in a precise and controlled manner. Input tray  14  includes a circular hopper  118  having a floor pan  120  (see FIG. 9) and an upright peripheral wall  122 . Floor pan  120  has an opening  124  adjacent to peripheral wall  122  for passing objects  36  therethrough to delivery conveyor  16 . A selector plate  126  in the form of a conical disc is located adjacent to floor pan  120  and has a plurality of holes  128  located equidistantly around the periphery of selector plate  126 . As conical selector plate  126  rotates, the holes  128  are selectively positioned over or located in registration with floor pan opening  124 . Holes  128  are dimensioned to loosely accommodate objects  36  and tapered entry slots  130  assist the objects loaded into input tray  14  to fall into these holes  128 . To assist in this, it will be noted that entry slots  130  are offset from the radial direction. Selector plate  126  rotates in the direction of arrow  131 , so entry slots  130  lead into the feed of the objects in tray  14 . Where the objects are not spherical, a rotating brush  132  driven by motor  134  is used to cause the objects to lie down flat in holes  128 . 
     As seen best in FIGS. 9 and 10, selector plate  126  has a peripheral edge portion  136  that is undercut adjacent to holes  128 , as indicated by dashed line  137  in FIG.  10 . This edge portion  136  has a thickness that is less than objects  36 , so that a portion of the objects  36  extends below selector plate  126  and slides along floor pan  120 . A spring finger  138  extends through an opening  139  in peripheral wall  22  and engages the objects  36  preventing them from falling through floor pan opening  124  by themselves. 
     As seen best in FIG. 9, a rotatable ejector wheel  140  having a plurality of radially disposed pistons  142  is mounted adjacent to peripheral wall  122  of hopper or input tray  14 . Ejector wheel  140  rotates in synchronization with selector plate  126  so that pistons  142  line up with respective holes  128  as they pass over opening  124 . An aligned piston  142  is then actuated to eject or push the object  36  past spring finger  138  and through peripheral opening  124  onto delivery conveyor  16  in engagement with a projection  38 . If desired, projections  38  can have resilient receiving portions  143  to cushion the landing of objects  36  as they fall onto projections  38 . Pistons  142  have cam followers  144  (see FIGS. 8 and 9) that engage a cam  146 , which together actuate the pistons. Cams  146  and cam followers  144  form timed actuator means for actuating pistons  142  to eject or push the objects  36  onto delivery conveyor  16 . Pistons  142  are spring biased into the extended position and cam  146  acting on cam followers  144  causes the pistons to retract until they are just over a selected hole  128 , at which time cam  146  ends allowing the release of the respective piston  146 . However, a double acting cam could be used as will be appreciated by those skilled in the art, to operate the pistons in both directions. Also, a single piston could be used, or fewer or more pistons could be used, with appropriate changes to the rotational speed of ejector wheel  140 . The rotation of ejector wheel  140 , together with the operation of cam  146  and cam followers  144  forms timed actuator means for actuating the pistons to push the objects through to the delivery conveyor  16 . The position of cam  146  is adjustable to vary the timing of pistons  142 . It will be noted from FIGS. 7,  8  and  10  that a guard  145  is provided to prevent objects  36  from entering the area of ejector wheel  140  unless they are properly positioned in the holes  128 . 
     It will also be noted in FIG. 8 that delivery conveyor  16  includes laterally adjustable guideways  147  for guiding or directing objects  36  along conveyor  16 . 
     As seen best in FIG. 1, ejector wheel  140  is driven by a suitable chain and sprocket drive  148 , and the entire assembly is allowed to swing up as indicated by arrow  150  for cleaning purposes. Conical selector plate  126  is driven by a chain and sprocket drive  152 . Selector plate  126  is mounted on a telescopic shaft  154  to allow selector plate  126  to lift up, also for cleaning purposes. 
     Referring again to FIG. 6, an oscillating film advancement mechanism in the form of pivoting fingers  156  located on the underside of table  42  may be provided to give a slight transverse push on wrapping film  22  where printed films are used in wrapping machine  10  and the film is subject to stretching. This transverse push prior to the following clamping device  28  closing, in effect, shortens or advances the wrapping film to compensate for any stretching and ensure that the film remains in registration in wrapping machine  10 . Pivoting adjustment fingers  156  are actuated by solenoids  158  which are controlled by proximity sensors or photocells  160 ,  162 . Sensor  160  is mounted on film stand  20  adjacent to wrapping film  22  (see FIG. 1) to detect film registration indicia. Sensor  162  is mounted adjacent gripping conveyor  18  to determine the position of clamping devices  28 . Sensor  160  is used to determine if the film is out of registration, and the other sensor  162  determines if the film is stretching and too late for clamping devices  28 . It will be appreciated that other mechanisms could be employed for this purpose as well. 
     In operation, a quantity of objects to be wrapped is loaded into hopper or input tray  14 . The rotating conical selector plate  126  causes the objects to fall into holes  128 . As the filled holes pass over floor pan opening  124 , first of all, they are prevented from dropping therethrough by spring finger  138  until the precise time required, at which time a respective piston  142  is released or actuated to push the object down onto delivery conveyor  16 . Film stand  20  and folder  26  then applies or places a continuous strip of wrapping film  22  on top of and in contact with objects  36  to be wrapped and folds the longitudinal edges of the film along side the objects to partially wrap the objects. The partial wrapped objects are then gripped through the wrapping film by the clamping devices  28 , or at least the gripping fingers,  52 ,  54  thereof. Gripping conveyor  18  then pulls the gripped objects  36  off the delivery conveyor  16 . The wrapping film is then crimped along the bottom edges to seal these peripheral edges and the wrapping film is transversely crimped and cut off between the objects. The clamping devices  28  are then opened to release the wrapped objects. 
     Having described preferred embodiments of the invention, it will be appreciated that various modifications may be made to the structures described above. For example, wrapping machine  10  is designed to wrap objects of a relatively uniform size and shape. Objects of different sizes and shapes can be accommodated with suitable modifications to the appropriate components. Many different types of drives could be used to operate the various conveyors and crimping wheels. Wrapping film  22  is shown to be applied on top of objects  36 , but the film could be arranged differently and applied beneath the objects and folded upwardly along side the objects, or even applied sideways to the objects. Input tray  14  is shown to be horizontally orientated, but it could be on an angle. Similarly, the gripper conveyor could be orientated differently, depending on how the wrapping film is applied to the objects. 
     Wrapping machine  10  could be used without input tray  14  provided some other type of magazine or feed device is used to supply objects to delivery conveyor  16 . Similarly, input tray  14  could be used by itself with another type of wrapping machine or device. 
     As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. Accordingly, the scope of the invention is to be construed in accordance with the substance defined by the following claims.