Strapping machine weld head with vibrating anvil

Information

  • Patent Grant
  • 6532722
  • Patent Number
    6,532,722
  • Date Filed
    Wednesday, July 18, 2001
    23 years ago
  • Date Issued
    Tuesday, March 18, 2003
    21 years ago
Abstract
A strapping head for a strapping machine of the type having a feed assembly and a chute that is configured to position, tension and seal strapping material around a load, includes a body and an anvil mounted to and movable relative to the body. A sealing member is disposed in the anvil for oscillating movement. A drive is operably connected to the sealing member and movable relative to the body to provide oscillating movement to the sealing member. First and second courses of strapping material overlie one another adjacent the sealing member, and oscillation of the sealing member effects a seal of the first and second courses of strapping material to one another.
Description




BACKGROUND OF THE INVENTION




Strapping machines are well known in the art. Typically these machines are used for securing straps around loads. One type of strapper is used with a plastic or polymeric strap and is a stationary arrangement in which the strapper is included as part of an overall manufacturing or packaging system.




A typical strapper includes a frame to which various components are mounted. A chute is mounted to the frame through which the strapping material is fed around a load. A strapping head and a drive or feed mechanism are mounted to the frame. The strapping material is fed from a source, by the feed assembly, through the strapping head. The strapping material traverses around the chute and back to the strapping head. Various guides may be mounted to the frame to provide a path for the strap. For example, a guide may be positioned at the feed assembly to guide the strap into feed wheels. A guide may also be positioned between the feed assembly and the strapping head to provide a strap path from the feed assembly to the head.




The strapping or welding head provides a number of functions. First, the strapping head includes a gripper having one or more gripper portions that grip the strap during the course of a strapping operation. The strapping head also includes a cutter to cut the strap from a strap source or supply. Last, the strapping head includes a sealer to seal an overlying course of strapping material onto itself. This seal is commonly referred to as a weld and is effected by heating one course of the strap by use of a vibrating element.




Known strapping heads include a body and an anvil between which the courses of strap materials traverse during a strapping operation and between which the strapping material courses are held during the welding operation. The gripper is mounted within the body and is operably connected to a camshaft having a plurality of cams thereon. Cam lobes move the gripper into and out of engagement with the strapping material to effect the necessary gripping functions during the strapping operation. The anvil is maintained rigidly against the body and a vibrating element within the body oscillates or vibrates thus creating friction and heat to effect the weld.




The vibrating element is disposed within the strapping head body. During the course of welding the strapping material onto itself, the gripper must maintain a sufficient pressure on the strap, against the anvil, to assure that the strap does not slip as the vibrating element vibrates (i.e., as the seal is made). To this end, complex linkages are required to assure that the gripper (mounted within the body) maintains contact with the strap (and the anvil) when the vibrating element is actuated. As such, strapping heads can be of complex, construction and design, particularly when large tensions are required in the strap to maintain the load bundled.




Accordingly, there exists a need for a simplified welding or strapping head for use in a strapping machine. Desirably, such a welding head eliminates the need for complex linkages otherwise required to maintain the gripping portion in contact with the strap (and the anvil) when the vibrating element is actuated. More desirably, such a strapping head is of a compact design. Most desirably, in such a strapping head, the vibrating element is removed from the strapping head body.




BRIEF SUMMARY OF THE INVENTION




A strapping head is used in a strapping machine of the type having a feed assembly and a chute. The strapping machine is configured to position, tension and seal strapping material around a load. The strapping head is positioned adjacent the chute.




The strapping head includes a body and an anvil mounted to and movable relative to the body. In a present embodiment, strapping head includes a side plate pivotally mounted to the body and the anvil is fixedly mounted to the side plate.




The strapping head further includes a gripper assembly disposed in the body and a sealing member disposed in the anvil for oscillating movement. A drive is operably connected to the sealing member to provide oscillating movement to the sealing member.




First and second courses of strapping material overlie one another in the strapping head, adjacent the sealing member. Oscillation of the sealing member effects a seal of the first and second courses of strapping material to one another.




In a preferred configuration, the sealing member drive is mounted to the side plate for movement with the anvil. To effect oscillation, the drive includes an eccentric drive element and the sealing member include a coupling portion for coupling with the eccentric drive element. The eccentric drive element can be configured as an eccentric shaft and the coupling portion can include a non-circular receiving opening for receiving the shaft. In such a configuration, a bearing is disposed on the shaft for contact with the receiving opening.




To accommodate the sealing member, the anvil includes a channel formed therein. Bearings can be disposed within the channel for receiving the sealing member.




The strapping head can include a platen for maintaining the first and second courses of strapping material compressed against the sealing element. The platen can be disposed between first and second grips within the gripper assembly, with the cutter disposed adjacent the platen.




These and other features and advantages of the present invention will be apparent from the following detailed description, in conjunction with the appended claims.











BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS




The benefits and advantages of the present invention will become more readily apparent to those of ordinary skill in the relevant art after reviewing the following detailed description and accompanying drawings, wherein:





FIG. 1

is a perspective view of an exemplary strapping machine having a strapping head with a vibrating member anvil embodying the principles of the present invention;





FIG. 2

is a schematic view of the exemplary strapping machine showing a load positioned in the chute region, and the strap source feeding the machine via a feed assembly;





FIG. 3

is a side perspective illustration of the strapping head, illustrating the weld motor mounted to the strapping head side plate;





FIG. 4

is a bottom perspective illustration of the anvil and vibrating member;





FIG. 5

is a bottom view of the anvil and vibrating member of

FIG. 4

; and





FIG. 6

is a cross-sectional view of the strapping head taken along lines


6





6


of FIG.


3


.











DETAILED DESCRIPTION OF THE INVENTION




While the present invention is susceptible of embodiment in various forms, there is shown in the drawings and will hereinafter be described a presently preferred embodiment with the understanding that the present disclosure is to be considered an exemplification of the invention and is not intended to limit the invention to the specific embodiment illustrated.




It should be further understood that the title of this section of this specification, namely, “Detailed Description Of The Invention”, relates to a requirement of the United States Patent Office, and does not imply, nor should be inferred to limit the subject matter disclosed herein.




Referring to the figures and in particular

FIG. 1

, there is shown a strapping machine


10


, having a strapping or weld head


12


with a vibrating member anvil


14


, embodying the principles of the present invention. The machine


10


includes, generally, a frame


16


, a strap chute


18


and a feed assembly


20


. A controller


22


provides automatic or semi-automatic operation and control of the strapper


10


. The weld head


12


includes generally, a body


24


and an anvil


26


. A gripper assembly


28


and a cutter


30


are carried by the body


24


. Preferably the cutter


30


is disposed within the gripper assembly


28


.




Referring to

FIG. 3

, the anvil


26


is movably mounted to the strapping head body


24


. In a preferred arrangement, the anvil


26


is fixedly mounted to a side plate


32


that moves relative to the body


24


. Preferably, the side plate


32


(and thus the anvil


26


) pivots about and relative to the body


24


. The anvil


26


moves between a closed position, in which the strap S is grasped, cut and welded, and an open position in which the strap S is allowed to freely pull from the head


12


following a strapping operation. The side plate


32


(and thus the anvil


26


) can be pivotally mounted to the strapping head body


24


by a pivot pin


34


.




Referring to

FIG. 6

, pivotal movement of the plate


32


and anvil


26


can be provided by, for example, a cam


36


mounted on a camshaft


38


disposed within the strapping head body


24


. The shaft


38


can be have other cams


40


,


42


,


44


(described below) thereon for moving portions of the gripper assembly


28


and cutter


30


into and out of engagement with the strap S. The plate cam


36


engages the side plate


32


, thus pivoting the side plate


32


and anvil


26


outwardly, away from the body


24


, into the open position. The side plate


32


is biased, by a biasing member such as a spring (not shown), to the closed position. A motor


46


drives the camshaft


38


.




The gripper assembly


28


includes at least two gripping portions (referred to as grips). In a current embodiment, the gripper assembly


28


includes an end grip


48


and a loop grip


50


. Preferably, a platen


52


or like element is disposed adjacent or within the gripper


28


that is brought into contact with the strap S during the welding operation, as will be described in more detail below. In a current embodiment, the platen


52


is positioned between the end grip


48


and the loop grip


50


, adjacent the cutter


30


.




Referring now to

FIGS. 3-5

, unlike known strapping heads, the present strapping head


12


utilizes a sealing member, such as the illustrated vibrating member


54


that is disposed in the anvil


26


. That is, while known strapping heads have the vibrating or welding element disposed within the head body, the present head


12


positions the vibrating member


54


within moving anvil


26


. The vibrating member


54


includes a welding end


56


having a weld pad or weld region


58


and a coupling end


60


.




A motor


62


is operably connected to the vibrating member


54


to effect, the necessary vibrations or oscillations of the member


54


. In a current combodiment, the motor


62


is mounted to the side plate


32


, and thus moves or pivots with the anvil


26


. In this manner, the motor


62


is fixedly mounted relative to the anvil


26


and vibrating member


54


.




The vibrating member


54


is disposed within an open channel


64


in the anvil


26


. The weld pad portion


58


of the member


54


contacts the strap S during the welding operation. The vibrating member


54


oscillates, in a generally reciprocating manner, in the direction indicated by the double headed arrow at


66


within the channel


64


.




As best seen in

FIG. 5

, to effect oscillation of the vibrating member


54


, the motor


62


includes an eccentric drive element, such as the exemplary eccentric drive shaft


68


extending through a receiving opening


70


in the vibrating member coupling end


60


. A bearing


72


is mounted to the shaft


68


. The eccentric shaft


68


is configured such that the axis of rotation A


1


is off-center of the shaft axis A


2


.




The receiving opening


70


is a non-circular opening. The opening


70


is elongated in a direction (indicated at


74


) transverse to the reciprocating movement direction


66


of the member


54


. The dimension of the opening


70


in the reciprocating movement direction (as indicated at


76


) is about the same as the diameter D of the eccentric shaft


68


. In this manner, the shaft


68


(having the bearing


72


fitted thereto) makes a tight fit in the opening


70


in the direction of movement


66


, but has dimensional freedom in the direction transverse to the reciprocating direction


66


. To this end, as the shaft


68


rotates eccentrically, it imparts reciprocating (i.e., linear) motion to the vibrating member


54


, but does not impart any side-to-side motion to the member


54


.




Those skilled in the art will appreciate that other means to drive the vibrating member


54


can be employed. For example, linkages, cogs, gears and the like can be used to impart vibrating motion to the member


54


. Likewise, other electromechanical, mechanical or electrical arrangements can be used. All such other means are within the scope and spirit of the present invention.




Referring now to

FIG. 5

, bearings


78


are disposed between the vibrating member


54


and the walls


80


defining the channel


64


. In a current embodiment, needle type bearings


78


are used to permit free reciprocating motion or oscillation


66


of the vibrating member


54


and to reduce friction between the vibrating member


54


and the channel walls


80


. The bearings


78


also ensure that movement of the member


54


within the channel


64


is restricted to reciprocating movement, rather than side-to-side movement.




As set forth above, the vibrating member


54


includes a weld pad or weld region


58


. This is the region that contacts the strap S during vibration to thus effect the weld or seal. In a current embodiment, the weld pad


58


is formed by cuts, (e.g., serrations) as indicated at


82


in the weld pad


58


. Those skilled in the art will recognize that there are various configurations and structures that can be used to effect the weld region


58


.




Operation of the sealing head


12


will now be described with reference to FIG.


6


. Strapping material S is fed into the strapping head


12


through opening


84


, traverses through the strapping head


12


, through the chute


18


and around the load L, and returns to the strapping head


12


, entering through second opening


85


. The first course of strapping material S


1


stops at a predetermined location in the strapping head


12


, as indicated at


86


. This stop


86


is provided by restricting the height h of the path through the head


12


at this point to about 1-½ times the thickness of the strap S.




Once the first course of strapping material S


1


reaches the stop


86


, a sensor (not shown) signals the controller


22


to stop strap feed. The end grip


48


is then moved toward the anvil


26


by contact of the cam


40


with the grip


48


. Once the end grip


48


is in place, the strap S is secured between the grip


48


and a gripper pad


49


on the anvil


26


. In a preferred configuration, the gripper pad


49


is replaceable. The strap S is tensioned by, for example, retraction of the strap S.




When a desired tension in the strap S is reached, the loop grip


50


moves into engagement with the strap S and anvil


26


, again by engagement of the cam


42


with the grip


50


. At this point in time, both the end grip


48


and loop grip


50


are fully engaged with the strap S secured between the respective grips


48


,


50


and gripper pads


49


in the anvil


26


.




The cutter


30


and platen


52


then move toward the anvil


26


by engagement of the cam


44


with the platen


52


. The cutter


30


cuts one course strap S to separate the strap S from the strap supply P. At the same time, the platen


52


presses the strap S against the anvil


26


.




The weld motor


62


is then actuated to oscillate the weld member to effect a weld in the strap material S at the area generally indicated at


88


. After a predetermined period of time during which acceptable weld strength is reached, and after cooling, the end grip


48


and loop grip


50


as well as the platen


52


and cutter


30


are moved away from the anvil


26


(by further rotation of the camshaft


38


) and the side plate


32


anvil


26


pivot outwardly, away from the body


24


. This releases the strap S from the head


12


.




The load L is then removed from the chute


18


region, and a new load is set in place for strapping. The side plate


32


and anvil


26


are then moved back into the closed position and strapping material S is again fed through the strapping head


12


, into the chute


18


around the load L and back to the strapping head, to repeat the strapping procedure.




In the present disclosure, the words “a” or “an” are to be taken to include both the singular and the plural. Conversely, any reference to plural items shall, where appropriate, include the singular.




From the foregoing it will be observed that numerous modifications and variations can be effectuated without departing from the true spirit and scope of the novel concepts of the present invention. It is to be understood that no limitation with respect to the specific embodiments illustrated is intended or should be inferred. The disclosure is intended to cover by the appended claims all such modifications as fall within the scope of the claims.



Claims
  • 1. A strapping head for a strapping machine of the type having a feed assembly and a chute, the strapping machine configured to receive first and second courses of associated strapping material, position, tension and seal the strapping material around a load, the strapping head configured for positioning adjacent the chute, the strapping head comprising:a stationary body; an anvil mounted to and movable relative to the body; a gripper assembly disposed in the body; a sealing member disposed in the anvil for oscillating movement; a side plate pivotally mounted to the stationary body; and a drive fixedly mounted to the side plate and operably connected to the sealing member to provide oscillating movement to the sealing member, wherein the anvil is mounted to the side plate, and wherein the first and second courses of strapping material are positioned to overlie one another adjacent the sealing member, and wherein oscillation of the sealing member effects a seal of the first and second courses of strapping material to one another.
  • 2. The strapping head in accordance with claim 1 wherein the drive includes an eccentric drive element and the sealing member includes a coupling portion for coupling with the eccentric drive element.
  • 3. The strapping head in accordance with claim 2 wherein the eccentric drive element is an eccentric shaft and the coupling portion includes a non-circular receiving opening for receiving the shaft.
  • 4. The strapping head in accordance with claim 3 wherein the shaft includes a bearing disposed thereon for contact with the receiving opening.
  • 5. The strapping head in accordance with claim 1 wherein the anvil includes a channel therein for receiving the sealing member.
  • 6. The strapping head in accordance with claim 5 including bearings disposed within the channel for receiving the sealing member.
  • 7. The strapping head in accordance with claim 1 including a platen for maintaining the first and second courses of strapping material compressed against the sealing element.
  • 8. The strapping head in accordance with claim 7 wherein the platen is disposed between first and second grips within the gripper assembly.
  • 9. The strapping head in accordance with claim 8 including a cutter disposed adjacent the platen.
  • 10. A strapping head for a strapping machine of the type having a feed assembly and a chute, the strapping machine configured to receive first and second courses of associated strapping material, position, tension and seal the strapping material around a load, the strapping head configured for positioning adjacent the chute, the strapping head comprising:a stationary body; a side plate movably mounted to the stationary body; an anvil fixedly mounted to the side plate and movable relative to the body with the side plate; a gripper assembly disposed in the body; a sealing member disposed for vibrating movement in the anvil; and a drive fixedly and directly mounted to the side plate, the drive being movable with the side plate and fixed relative to the anvil, the drive being operably connected to the sealing member, wherein first and second courses of strapping material are positioned to overlie one another adjacent the sealing member, and wherein vibration of the sealing member effects a seal of the first and second courses of strapping material to one another.
  • 11. The strapping head in accordance with claim 10 wherein the drive includes an eccentric drive shaft and the sealing member includes a coupling portion having a slotted opening for receiving the eccentric drive shaft.
  • 12. The strapping head in accordance with claim 11 including a bearing disposed on the eccentric drive shaft for contact with the receiving opening.
  • 13. The strapping head in accordance with claim 10 wherein the anvil includes a channel therein for receiving the sealing member, and including bearings disposed within the channel for contacting the sealing member.
  • 14. The strapping head in accordance with claim 10 including a platen for maintaining the first and second courses of strapping material compressed against the sealing element.
  • 15. The strapping head in accordance with claim 14 wherein the platen is disposed between first and second grips within the gripper assembly.
  • 16. The strapping head in accordance with claim 15 including a cutter disposed adjacent the platen.
US Referenced Citations (4)
Number Name Date Kind
4079667 Lems et al. Mar 1978 A
4378262 Annis, Jr. Mar 1983 A
4479834 Kobiella Oct 1984 A
4776905 Cheung et al. Oct 1988 A