Strapping machine with a strap tightening adjustment unit

Information

  • Patent Grant
  • 6467243
  • Patent Number
    6,467,243
  • Date Filed
    Friday, July 27, 2001
    23 years ago
  • Date Issued
    Tuesday, October 22, 2002
    22 years ago
Abstract
A strapping machine includes a machine body with a package-strapping space. A strap is fed to the package-strapping space. A spring-loaded swing arm is pivoted to the machine body, and is associated with a rotating shaft via a cam unit such that rotation of the shaft results in turning of the swing arm relative to the machine body. An electrically operated clamp unit is mounted movably on the swing arm, and is movable relative to a strap passage in the swing arm. A delay circuit is electrically coupled to a detecting device and the clamp unit. When the detecting device detects a first position of the swing arm, the delay circuit will actuate the clamp unit to move from a releasing position to a clamping position after a preset delay time. When the detecting device detects a second position of the swing arm, the clamp unit is immediately actuated to move from the clamping position to the releasing position.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




The invention relates to a strapping machine, more particularly to a strapping machine with a strap tightening adjustment unit of a simple structure.




2. Description of the Related Art




Referring to

FIGS. 1

to


3


, a conventional strapping machine is shown to include a machine body


1


, a strap supply reel


14


, a strap feed unit


13


, a rotating shaft unit


122


, and a strap tightening adjustment unit


4


.




As illustrated, the machine body


1


defines an accommodating space


11


and a package-strapping space


12


above the accommodating space


11


. The strap supply reel


14


is mounted on an exterior of the machine body


1


. A bundle of strap


2


is mounted on the strap supply reel


14


, and has a leading end fed into the package-strapping space


12


by the strap feed unit


13


in such a manner that a package strapping operation can be done in the package-strapping space


12


. The rotating shaft unit


122


is journalled in the accommodating space


11


of the machine body


1


, and is formed with a cam unit


123


.




The strap tightening adjustment unit


4


includes a spring-loaded swing arm


41


, a clamp unit


5


, and a strap tension adjuster


6


. A mounting shaft


113


extends through a mounting bracket


111


of the machine body


1


and the swing arm


41


to mount the latter pivotally within the accommodating space


11


. The swing arm


41


is further associated with the rotating shaft unit


122


via the cam unit


123


in such a manner that rotation of the shaft unit


122


results in turning of the swing arm


41


relative to the machine body


1


along a travelling path


131


between an upper position adjacent to the package-strapping space


12


and a lower position distal from the package-strapping space


12


. The swing arm


41


defines a strap passage


414


to permit extension of the strap


2


therethrough, and a rod-path


415


in spatial communication with the strap passage


414


. The clamp unit


5


includes a clamp piece


54


, a push rod


51


, and a torsional spring


52


. The clamp piece


54


is mounted pivotally on the swing arm


41


via a pivot


53


. The push rod


51


is disposed movably in the rod-path


415


of the swing arm


41


, and is operably associated with the clamp piece


54


. The torsional spring


52


is sleeved around the pivot


53


so as to urge the push rod


51


in the rod-path


415


toward a first direction away from the strap passage


414


so as to relieve clamping of the clamp piece


54


relative to the strap


2


. The strap tension adjuster


6


includes an adjuster shaft


61


which is mounted rotatably in the mounting bracket


111


of the accommodating space


11


and which extends parallel to and adjacent to the mounting shaft


113


, a spring-loaded rod pusher


64


which is sleeved on the mounting shaft


113


and which urges the push rod


51


to move in a second direction opposite to the first direction so as to result in clamping of the clamp piece


54


relative to the strap


2


in the strap passage


414


, and a tension adjusting wheel


62


which is fixed eccentrically on the adjuster shaft


61


and which is in sliding contact with the rod pusher


64


via a coupler unit


63


.




When the swing arm


41


is pivoted to a position between the upper and lower positions by virtue of rotation of the shaft unit


122


, the rod pusher


64


and the coupler unit


63


concurrently rotate with the swing arm


41


. Collision of a protrusion


631


on the coupler unit


63


with the adjusting wheel


62


results in stoppage of the rotation of the coupler unit


63


on the shaft


113


, which in turn, results in movement of the clamp piece


54


in the second direction toward the strap passage


414


of the swing arm


41


by virtue of urging action of the rod pusher


64


against the push rod


51


(see FIG.


4


), thereby clamping and tightening the strap


2


around the package that is disposed in the package-strapping space


12


of the machine body


1


.




Note that the strap tightening adjustment unit


4


of the conventional strap machine includes a relatively large number of components, and is therefore consequently complicated in structure and incurs a long assembly time during the manufacture of the conventional strapping machine.




SUMMARY OF THE INVENTION




Therefore, the object of this invention is to provide a strapping machine with a strap tightening adjustment unit of a simple structure so as to overcome the aforementioned disadvantages that are associated with the conventional strapping machine.




Accordingly, a strapping machine of the present invention includes a machine body, a strap supply reel, a strap feed unit, a rotating shaft unit, and a strap tightening adjustment unit. The machine body defines an accommodating space and a package-strapping space above the accommodating space. The strap supply reel is mounted on the machine body, and is adapted to hold a bundle of strap thereon. The strap feed unit is capable of feeding the strap from the strap supply reel to the package-strapping space of the machine body. The rotating shaft unit is journalled in the accommodating space of the machine body, and is formed with a cam unit. The strap tightening adjustment unit includes a spring-loaded swing arm, an electrically operated clamp unit, a detecting device, and a delay circuit. The swing arm is pivoted to the machine body within the accommodating space, and is associated with the rotating shaft unit via the cam unit in such a manner that rotation of the shaft unit results in turning of the swing arm relative to the machine body between an upper position adjacent to the package-strapping space and a lower position distal from the package-strapping space. The swing arm defines a strap passage which is adapted to permit extension of the strap therethrough. The clamp unit is mounted movably on the swing arm, and is movable relative to the strap passage between a clamping position, in which the strap is clamped by the clamp unit, and a releasing position, in which the strap is released from the clamp unit. The delay circuit is electrically coupled to the detecting device and the clamp unit. When the detecting device detects a first position of the swing arm between the upper and lower positions, the delay circuit will actuate the clamp unit to move from the releasing position to the clamping position after a preset delay time. When the detecting device detects a second position of the swing arm between the first and lower positions, the clamp unit is immediately actuated to move from the clamping position to the releasing position.











BRIEF DESCRIPTION OF THE DRAWINGS




Other features and advantages of this invention will become more apparent in the following detailed description of the preferred embodiment of this invention, with reference to the accompanying drawings, in which:





FIG. 1

is a schematic view of a conventional strapping machine for strapping a package;





FIG. 2

is a fragmentary exploded perspective view to illustrate a strap tightening adjustment unit of the conventional strapping machine;





FIG. 3

is a fragmentary assembled perspective view of the conventional strapping machine, illustrating how the strap tightening adjustment unit is mounted on a machine body;





FIG. 4

is a fragmentary schematic view of the conventional strapping machine, illustrating how the strap tightening adjustment unit is operated;





FIG. 5

is a schematic view of a preferred embodiment of a strapping machine according to the present invention;





FIG. 6

is a fragmentary schematic view of the preferred embodiment, illustrating how a swing arm of a strap tightening adjustment unit is mounted on a machine body;





FIG. 7

is a fragmentary schematic view of the preferred embodiment, illustrating how the swing arm of the strap tightening adjustment unit is actuated so as to move the same to a first position;





FIG. 8

is a schematic view of the preferred embodiment, viewed from line VIII—VIII in

FIG. 7

, illustrating how a first micro switch is actuated by a first actuator mounted fixedly on a rotating shaft;





FIG. 9

shows a clamp unit of the preferred embodiment at a clamping position;





FIG. 10

is a fragmentary schematic view of the preferred embodiment, illustrating how the swing arm of the strap tightening adjustment unit is actuated in order to tighten a strap relative to the package;





FIG. 11

illustrates how a second micro switch is actuated by a second actuator in the preferred embodiment;





FIG. 12

is a fragmentary schematic view of the preferred embodiment, illustrating how the swing arm of the tightening adjustment unit is restored to its initial position; and





FIG. 13

illustrates how a third micro switch is actuated by a third actuator in the preferred embodiment.











DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT




Referring to

FIGS. 5

,


6


, and


7


, the preferred embodiment of a strapping machine for strapping a package


90


according to the present invention is shown to include a machine body


7


, a strap supply reel


60


, a strap feed unit


73


, a rotating shaft unit


722


, and a strap tightening adjustment unit


9


.




As illustrated, the machine body


7


defines an accommodating space


70


and a package-strapping space


71


above the accommodating space


70


. The package


90


is disposed in the package-strapping space


71


of the machine body


7


for strapping.




The strap supply reel


60


is mounted on the machine body


7


, and holds a bundle of strap


8


thereon.




The strap feed unit


73


is disposed in the accommodating space


70


of the machine body


7


, and can feed the strap


8


from the strap supply reel


60


to the package-strapping space


71


in such a manner that after encircling around the package


90


, a distal end of the strap


8


is fixedly retained underneath on a support plate that supports the package


90


thereon.




The rotating shaft unit


722


is journalled between two mounting walls


712


(only one is shown in

FIGS. 6 and 7

) in the accommodating space


70


of the machine body


7


, and is formed with a cam unit


723


.




The strap tightening adjustment unit


9


includes a spring-loaded swing-arm


91


, an electrically operated clamp unit


95


, a detecting device


100


, and a delay circuit


104


. The swing arm


91


has a lower portion


911


pivoted to a pivot seat


711


within the accommodating space


70


of the machine body


7


, and is associated with the rotating shaft unit


722


via the cam unit


723


in such a manner that rotation of the shaft unit


722


results in turning of the swing arm


91


relative to the seat


711


between an upper position adjacent to the package-strapping space


71


, as best shown in

FIG. 5

, and a lower position (not shown) distal from the package-strapping space


71


. The swing arm


91


has an upper portion


912


that is formed with a strap passage


916


(see

FIG. 9

) to permit extension of the strap


8


therethrough when the strap


8


is fed by the strap feed unit


73


from the strap supply reel


60


to the package-strapping space


71


of the machine body


7


. The clamp unit


95


is mounted movably on the swing arm


91


, and is movable relative to the strap passage


916


between a clamping position, in which the strap


8


is clamped by the clamp unit


95


, and a releasing position, in which the strap


8


is released from the clamp unit


95


.




The delay circuit


104


is electrically coupled to the detecting device


100


and the clamp unit


95


in such a manner that when the detecting device


100


detects a first position of the swing arm


91


between the upper and lower positions, as best shown in

FIG. 7

, the delay circuit


104


will actuate the clamp unit


95


to move from the releasing position to the clamping position after a preset delay time. Under this condition, the strap


8


around the package


90


is tightened by virtue of rotation of the shaft unit


722


and concurrent movement of the upper portion


912


of the swing arm


91


from the upper position to the first position. When the detecting device


100


detects a second position of the swing arm


91


between the first and lower positions (see FIGS.


10


and


11


), the clamp unit


95


is immediately actuated to move from the clamping position to the releasing position, which in turn releases the strap


8


from the clamp unit


95


.




The detecting device


100


includes first and second micro switches


101


,


102


which are disposed in the accommodating space


70


of the machine body


7


adjacent to the rotating shaft unit


722


and which are electrically coupled to the delay circuit


104


, and first and second actuators


724


,


725


which are fixed on the rotating shaft unit


722


and which are capable of contacting the first and second micro switches


101


,


102


respectively when the swing arm


91


is at the first and second positions, as best shown in

FIGS. 8 and 11

. A drive unit


72


is provided for rotating the rotating shaft unit


722


. The detecting device


100


further includes a third micro switch


103


which is disposed in the accommodating space


70


of the machine body


7


adjacent to the rotating shaft unit


722


and which is electrically coupled to the drive unit


72


, and a third actuator


726


which is fixed on the rotating shaft unit


722


and which is capable of contacting the third micro switch


103


when the swing arm


91


is at the lower position to control the drive unit


72


to stop rotation of the shaft unit


722


, as best shown in

FIGS. 12 and 13

. Under this condition, the swing arm


91


is moved back to its initial position of

FIG. 12

by virtue of tension force of a spring


914


which interconnects the mounting wall


712


and the swing arm


91


.




In this preferred embodiment, the delay circuit


104


includes a motor


97


operably connected to the clamp unit


95


via a turning plate


96


and a push rod


92


(see

FIG. 9

) in such a manner that the motor


97


rotates in a first direction so as to move the clamp unit


95


from the releasing position to the clamping position when the first actuator


724


contacts the first micro switch


101


. In the same manner, the motor


97


rotates in a second direction opposite to the first direction so as to move the clamp unit


95


from the clamping position to the releasing position when the second actuator


725


contacts the second micro switch


102


.




Referring to

FIG. 9

, the clamp unit


95


preferably includes a u-shaped clamp seat


913


which is fixed on the upper portion


912


of the swing arm


91


(see

FIG. 6

) and which defines the strap passage


916


and a push-rod path


917


that is disposed above the strap passage


916


and that receives the push rod


92


therein, a clamp piece


950


pivoted to the seat


913


via a pivot


93


, and an urging member


94


that is sleeved around the pivot


93


and that urges the clamp piece


950


via the push rod


92


so as to clamp the strap


8


in the strap passage


916


of the seat


913


when the motor


97


rotates in the first direction.



Claims
  • 1. A strapping machine for strapping a package, comprising:a machine body defining an accommodating space and a package-strapping space above said accommodating space; a strap supply reel mounted on said machine body and adapted to hold a bundle of strap thereon; a strap feed unit capable of feeding the strap from said strap supply reel to said package-strapping space; a rotating shaft unit journalled in said accommodating space, and formed with a cam unit; a strap tightening adjustment unit including a spring-loaded swing arm pivoted to said machine body within said accommodating space and associated with said rotating shaft unit via said cam unit in such a manner that rotation of said shaft unit results in turning of said swing arm relative to said machine body between an upper position adjacent to said package-strapping space and a lower position distal from said package-strapping space, said swing arm defining a strap passage adapted to permit extension of the strap therethrough, an electrically operated clamp unit mounted movably on said swing arm and movable relative to said strap passage between a clamping position, in which the strap is clamped by said clamp unit, and a releasing position, in which the strap is released from said clamp unit, a detecting device, and a delay circuit electrically coupled to said detecting device and said clamp unit, wherein, when said detecting device detects a first position of said swing arm between said upper and lower positions, said delay circuit will actuate said clamp unit to move from said releasing position to said clamping position after a preset delay time, and wherein, when said detecting device detects a second position of said swing arm between said first and lower positions, said clamp unit is immediately actuated to move from said clamping position to said releasing position.
  • 2. The strapping machine as defined in claim 1, wherein said detecting device includes first and second micro switches disposed in said accommodating space of said machine body adjacent to said rotating shaft unit and electrically coupled to said delay circuit, and first and second actuators which are fixed on said rotating shaft unit and which are capable of contacting said first and second micro switches respectively when said swing arm is at said first and second positions.
  • 3. The strapping machine as defined in claim 2, further comprising a drive unit for rotating said rotating shaft unit, said detecting device further including a third micro switch disposed in said accommodating space of said machine body adjacent to said rotating shaft unit and electrically coupled to said drive unit, and a third actuator which is fixed on said rotating shaft unit and which is capable of contacting said third micro switch when said swing arm is at said lower position so as to control said drive unit to stop rotation of said rotating shaft unit.
  • 4. The strapping machine as defined in claim 2, wherein said delay circuit includes a motor operably connected to said clamp unit, said motor rotating in a first direction so as to move said clamp unit from said releasing position to said clamping position when said first actuator contacts said first micro switch, said motor rotating in a second direction opposite to said first direction so as to move said clamp unit from said clamping position to said releasing position when said second actuator contacts said second micro switch.
US Referenced Citations (7)
Number Name Date Kind
RE27744 Billett et al. Aug 1973 E
4378262 Annis, Jr. Mar 1983 A
4516488 Bartzick et al. May 1985 A
4569186 Mori et al. Feb 1986 A
5267508 Yoshino Dec 1993 A
5377477 Haberstroh et al. Jan 1995 A
5809873 Chak et al. Sep 1998 A