Abstract:
An aim assembly includes a hub movable about a central axis and at least one support operably connected to the hub. At least one arm is operably connected to the at least one support and thereby movable about the central axis in a predetermined path. At least one adjustment mechanism is located at the central axis and is capable of altering the predetermined path during movement of the at least one support about the central axis. A method of operating an arm assembly includes locating at least one hub at a central axis and moving at least one arm about the central axis in a predetermined path. The at least one arm is operably connected to the at least one hub via at least one support. An adjustment mechanism is engaged thereby altering the predetermined path during movement of the at least one arm about the central axis.

Description:
BACKGROUND 
     The subject matter disclosed herein generally relates to packaging machines. More specifically, the subject invention relates to a packaging machine having an adjustable wand. 
     Packaging machines typically convey a product or group of products along a pathway, for example, a conveyor. A piece of wrapping material is typically located on the pathway underneath the product. As the product travels along the pathway, am arm, typically called a “wand”, is moved in a predetermined path, lifting a trailing portion of the wrapping material over the product and to the front of the product to form a roughly tubular shape of wrapping material around the product. The desired path of the wand depends on the size and shape of the product or group of products to be wrapped in the material. To change the path of the wand to accommodate products of different shapes and sizes, the packaging machine must typically be stopped, and some intervention by an operator, often in the form of changing parts on the packaging machine, must occur to perform the necessary adjustments to the path of the wand. Stoppage of the machine to perform adjustments results in machine downtime which decreases productivity of the packaging machine, and reduces flexibility of usage of the packaging machine. The art would well receive an adjustable wand for a packaging machine whose path is changeable without stopping the machine or requiring manual intervention by an operator. 
     SUMMARY 
     Disclosed herein is an arm assembly including a hub movable about a central axis and at least one support operably connected to the hub. At least one arm is operably connected to the at least one support and thereby movable about the central axis in a predetermined path. At least one adjustment mechanism is located at the central axis and is capable of altering the predetermined path during movement of the at least one support about the central axis. 
     Further disclosed herein is a wrapping machine including a product conveying portion and an arm mechanism disposed at the product conveying portion. The arm mechanism including at least one hub movable about a central axis and at least support operably connected to the at least one hub. At least one arm is operably connected to the at least one support and is thereby movable about the central axis in a predetermined path. At least one adjustment mechanism is located at the central axis and is capable of altering the predetermined path during movement of the at least one support about the central axis. 
     Further disclosed herein is a method of operating an arm assembly including locating at least one hub at a central axis and moving at least one arm about the central axis in a predetermined path. The at least one arm is operably connected to the at least one hub via at least one support. An adjustment mechanism is engaged thereby altering the predetermined path during movement of the at least one arm about the central axis. 
     These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is perspective view of an embodiment of a packaging machine; 
         FIG. 2  is a partially-exploded view of an embodiment of a hub of a packaging machine; and 
         FIG. 3  is a partial end view of an embodiment of a hub drive for a packaging machine. 
         FIG. 4  is a partial end view of an embodiment of a packaging machine; 
         FIG. 5  is another partial end view of the packaging machine of  FIG. 4 ; and 
         FIG. 6  is a partial end view of another embodiment of a packaging machine. 
     
    
    
     The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Shown in  FIG. 1  is an embodiment of a wrap machine  10 . The wrap machine  10  includes a product belt  12  which is formed into a surface to move a product from a first end  14  of the wrap machine  10  to a second end  16  of the wrap machine  10 . The belt  12  may be supported by one or more belt rollers  18  which may be rotably secured to a machine frame  20 . The belt  12  is driven by, for example, an electric motor (not shown) or the like. In some embodiments, the electric motor is operably connected to a drive belt  22  which urges rotation of one or more drive pulleys  24  to urge the belt  12  over the one or more rollers  18 , and other structure of the wrapping machine  10 . 
     The wrap machine  10  includes one or more wands  26 . Each wand  26  extends laterally from a first side  28  toward a second side  30  of the belt  12 . Each wand  26  is supported at at least one end by a support  34 , the support  34  supported at a hub  32  of the wrap machine  10 . The wands  26  illustrated in  FIG. 1  are supported at two hubs  32  disposed at the first side  28  and the second side  30  of the belt  12 , but it is to be appreciated that, in some embodiments, each wand  26  may be supported only at one hub  32 . Each hub  32  is rotably connected to the machine frame  20 . For example, as shown in  FIG. 2 , the hub  32  is substantially circular in cross section and extends through a hub hole  36  in the machine frame  20 . At least one hub  32  is configured as a drive hub  38 . The drive hub  38  is connected to a hub drive  40  (shown in  FIG. 1 ) which may be, for example, a belt or a chain. The hub drive  40  urges rotation of the drive hub  38  which in turn drives the at least one wand  26  through a path  42  over the belt  12 . In some embodiments, as shown in  FIG. 1 , the path  42  may be substantially circular, but other shapes, including elliptical are contemplated within the present scope. Further, as shown in  FIG. 1 , an axis of rotation  44  of the hub  32  lies in an extension of the surface of the belt  12 . In some embodiments, however, the axis of rotation  44  may be disposed either above or below the surface of the belt  12 . 
     To increase flexibility and reduce downtime of the machine  10 , a distance  46  of the wand  26  from the axis of rotation  44  is adjustable to accommodate different product sizes and/or shapes. As shown in  FIG. 2 , each hub  32  includes an adjustment mechanism  48  located in a housing  50 . The housing  50  includes support openings  70  through which the supports  34  extend, in a location radially outboard of the adjustment mechanism  48 . In some embodiments, the adjustment mechanism  48  may be a wheel, which engages the supports  34  via, for example, friction. In other embodiments, the adjustment mechanism  48  may be a gear which includes a plurality of gear teeth  64  that mesh with corresponding support teeth  56  on the support  34 . The adjustment mechanism  48  engages with the supports  34  such that rotation of the adjustment mechanism  48  results in the support  34  moving substantially tangentially along the adjustment mechanism  48  thereby increasing the distance  46  of the wand  26  from the axis of rotation  44 . In some embodiments, it may be desired to utilize other quantities of wands  26 . For example, some embodiments may utilize a single wand  26 . The wand  26  may be adjustable via a single adjustment mechanism  48  at each hub  32  as described above, or other schemes may be utilized. For example, the support  34  may be positioned between two adjustment mechanism  48 , which when rotated, result in movement of the support  34  to change the position of the wand  26 . 
     Referring again to  FIG. 2 , adjustment of the wand  26  position utilizing the adjustment mechanism  48  and supports  34  may be achieved on the fly during operation of the machine  10 . For example, one or more drives  52  are disposed at each hub  32  and, as shown, may be substantially concentric with the adjustment mechanism  48 . The one or more drives  52  are, for example, pulleys, gears, servomotors, direct drives, or the like. In an exemplary embodiment, two drives  52 , configured as pulleys, are disposed at a hub  32 . A first drive  52 , in this embodiment the drive  52  closest to the housing  50  is operably connected to the housing  50  such that rotation of the first drive  52  results in rotation of the housing  50 . A second drive  52  is operably connected to adjustment mechanism  48 . When the second drive  52  is rotated, adjustment mechanism  48  is driven, thus urging movement of the supports  34  positionally in or out of the housing  50 . As shown in  FIG. 3 , the drives  52  are driven by, for example, one or more drive belts  54 , which may be belts or chains or the like. The drive belt  54  is driven by, for example, and electric motor  56  or the like. Adjustment of the wand  26  position may then be achieved by rotation of the drive  52  a desired amount at a desired time, and can be accomplished while the machine  10  is in operation. Further, in some embodiments, one or more programmable controllers  58  connected to the electric motor  56  may provide programmed instructions to the electric motor  56  to drive the drives  52  a predetermined amount at predetermined times thereby adjusting the wand  26  position. In further embodiments, the controllers  58  are operatively connected to one or more sensors positioned upstream of the wrapping machine  10  that provide information to the controllers  58  about the size and shape of an approaching product. With this information the controllers  58  are programmed to automatically adjust the wrapping machine  10  to accommodate the approaching product. 
     Referring again to  FIG. 1 , the wands  26  may be utilized a part of a wrapping machine  10 . Product  60  flows down an upstream conveyor  62  and continues onto the belt  12 , on which a layer of wrapping material  64 , for example, shrink wrap, has been placed so as to be between the belt  12  and the product  60 . As the wand  26  rotates about the axis of rotation  44 , the wand  26  lifts an upstream portion  66  of the wrapping material  64  from the belt  12  and over the product  60  to form a roughly tubular shape of wrapping material  64  around the product  60 . The product then proceeds onto a downstream conveyor  68  toward, for example, a heating unit (not shown) which shrinks the wrapping material  64  around the product  60 . As product  60  of a different size or shape flows to the belt  12 , the pulleys  52  may be driven to adjust the position of the wands  26  to properly wrap the product  60 . 
     In an exemplary embodiment, adjustments to the position of the wands  26  are made between individual products  60  to accommodate the approaching product  60 . It is to be appreciated, however, that adjustments to the position of the wands  26  can be made at any time. For example, the position may be adjusted substantially continuously such that the path described is a substantially a constant distance from the product  60  to facilitate more smoothly wrapping the product  60 . In some embodiments where the product  60  has a flat top, the path  42  may be a substantially straight line over the top of the product  60 . In other embodiments, elliptical paths  42  may be used with elliptical products  60  and irregularly shaped profiles  42  may be utilized for irregularly shaped product  60  if so desired. 
     At any point in time, a position of each wand  26  can be expressed relative to the axis of rotation  44 . As shown in  FIG. 4 , the wand  26  has a position (x,y) relative to the axis of rotation  44  (0,0). The position (x,y) depends on a radius (K) of the adjustment mechanism  48 , and effective length (S) of the support  34 , and an angular rotation (Φ) of the adjustment drive. Position (x,y) is expressed as:
 
 x=K  sin Φ+ S  cos Φ
 
and
 
 y=−K  cos Φ+ S  sin Φ
 
Given a desired position (x,y) of the wand  26 , the position (x,y) can be reached by changing the effective length (S) via the adjustment mechanism  48  and by rotation of the hub  32  about the central axis  44 . For a particular position (x,y), the effective length (S) of the support  34  is:
 
 S= sqrt( x   2   +y   2   −K   2 )
 
The angular rotation of the hub  32  is:
 
Φ=arc sin [( xK+Sy )/( K   2   +S   2 )]
 
or
 
Φ=arc sin [( Kx+y *sqrt( x   2   +y   2   −K   2 ))/( x   2   +y   2 )]
 
An angular position (θ) of the wand  26  is expressed as:
 
θ=α+Φ
 
where
 
α= S/K  or sqrt( x   2   +y   2   −K   2 )/ K  
 
Utilizing the above equations, given a desired position (x,y) of the wand  26 , the necessary effective length (S) and angular rotation (Φ) can be determined. The effective length (S) and angular rotation (Φ) may be utilized by, for example, the controller  58  to drive the wand  26  to a desired position.
 
As shown in  FIG. 5 , the path  42  may comprise a number of discreet legs  62  between positions, for example, (x 1 , y 1 ) and (x 4 , y 4 ) via (x 2 , y 2 ) and (x 3 , y 3 ). The movement of the wand  26  from, for example, (x 1 , y 1 ) to (x 2 , y 2 ) is defined by:
 
Δ S= sqrt[( x   2   −x   1 ) 2 +( y   2   −y   1 ) 2   −K   2 ] and
 
ΔΦ=arc sin [( K* ( x   2   −x   1 )+( y   2   −y   1 )*sqrt(( x   2   −x   1 ) 2 +( y   2   −y   1 ) 2   −K   2 ))/(( x   2   −x   1 ) 2 +( y   2   −y   1 ) 2 )]
 
Further, each leg  62  may be subdivided into sublegs to further define the motion of the wand  26  between, for example, (x 1 , y 1 ) and (x 2 , y 2 ). In one example where 32 sublegs are utilized between (x 1 , y 1 ) and (x 2 , y 2 ):
 
 x   2   −x   1 =32 *Δx  and
 
 y   2   −y   1 =32 *Δy  
 
     In one embodiment, as shown in  FIG. 6 , the support  34  is configured, for example, bent, so that the wand  26  is in direct alignment with the axis of rotation  44 . In this embodiment, since there is no need to compensate for the radius (K), the positional calculations are simplified to:
 
 X=S  cos Φ and
 
 Y=S  sin Φ.
 
For a given position (x, y), the necessary S and Φ are:
 
 S= sqrt( x   2   +y   2 ) and
 
Φ=arc tan( y/x ).
 
Similarly, to move the wand  26  between positions (x 1 , y 1 ) and (x 2 , y 2 ):
 
Δ S= sqrt(( x   2   −x   1 ) 2 +( y   2   −y   1 ) 2 ) and
 
ΔΦ=arc tan(( y   2   −y   1 )/( x   2   −x   1 )).
 
     It is to be appreciated that use of the adjustment apparatus is not limited to wrapping machines  10 . For example, the wands  26 , or the supports  34  themselves, may be configured to pick up a product at a first location and move the product to a second location via rotation about the axis of rotation  44  and/or moving the supports  34  to change position of the wands  26 . 
     While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims