Package making – With means responsive to a sensed condition – Of receptacle or cover feed or adjunct feed or application
Reexamination Certificate
1999-02-04
2001-10-23
Gerrity, Stephen F. (Department: 3721)
Package making
With means responsive to a sensed condition
Of receptacle or cover feed or adjunct feed or application
C053S588000, C053S204000, C053S389400, C242S420600
Reexamination Certificate
active
06305145
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a wrapping apparatus.
Prior specification EP 0 544 312 A1 discloses a wrapping apparatus for winding a web of wrapping foil around an object to be packaged. This wrapping apparatus comprises a foil dispenser arranged to circulate along a ring-like endless track around the object to be packaged. In the prior-art apparatus the track is of a substantially elliptical form. The track comprises a straight track portion which passes through the center hole of the cylindrical object to be packaged. The straight track portion extends outside the hole to a distance from the end of the cylindrical object. The track also comprises a curved portion which forms a curved track between ends of the straight track portion and around the object to be packaged. The foil dispenser comprises a frame and a detachable and replaceable foil roll mounted on the frame. Furthermore, the foil dispenser comprises supporting elements for supporting the foil roll on the frame, and tensioning means for braking the delivery of foil from the roll to maintain a predetermined foil tension.
A special problem which arises from the form of the track is that, during wrapping, in certain parts along the track, the foil span (i.e. a portion of the foil extending between a support point, e.g. edge point, of the object to be packaged and the foil dispenser) does not lengthen, but, instead, becomes shorter. Therefore the foil web would slacken if the tensioning device would not eliminate the slack. In EP 0 544 312 A1, the foil tensioning device is a complicated mechanical foil storage device comprising a number of fixedly mounted deflecting rollers, a number of flexibly mounted deflecting rollers and loading means for flexibly applying to the flexibly mounted rollers a load acting in a direction away from the fixedly mounted rollers so as to maintain tension in a variable amount of foil web passing along a winding path around the deflecting rollers.
A problem with this prior-art apparatus is that the foil storage takes up a relatively large space in the foil dispenser. Moreover, the structure is heavy, complex and expensive. Especially in types of wrapping apparatus in which the foil dispenser should be as small as possible to be able to pass e.g. through the central hole of a foil roll, the large size of the prior-art structure leads to problems. The heavy weight again results in a necessity to use a foil dispenser drive mechanism and motor accordingly dimensioned.
An object of the present invention is to eliminate the drawbacks described above.
A specific object of the present invention is to present a wrapping apparatus in which the foil dispenser is as simple as possible, contains few components and is light and cheap.
SUMMARY OF THE INVENTION
According to the invention, the tensioning arrangement comprises a sensor for continuously sensing foil web tension and an electric motor for driving the foil roll. The torque, speed of rotation and direction of rotation of the electric motor are controlled on the basis of foil tension as detected by the sensor such that a foil tension is achieved that remains within predetermined limits.
The invention has the advantage that, to maintain a sufficient foil tension, the foil roll can be caused to rotate in the direction of foil delivery as well as in the opposite direction as necessary according to the measured foil tension. As the inertia of the foil roll in certain situations tends to cause excessive foil delivery, the torque of the electric motor is increased or decreased as necessary in accordance with the foil tension as detected by the sensor. Also the speed of rotation of the electric motor can be controlled. The foil dispenser contains few parts and is simple, small, light and cheap.
In one embodiment of the apparatus, the foil dispenser comprises a first diverting element which is connected to the frame and around which the foil web drawn from the foil roll passes. The said first diverting element contacts the first side of the foil. A second diverting element is connected to the frame at a distance from the first diverting element and also contacts the first side of the foil. The sensor comprises a spring-loaded lever arm, a turning axle, which is supported by a bearing on the frame and to which the lever arm is attached, and a third diverting element, which is connected to the end of the lever arm between the first and second diverting elements. The third diverting element contacts the second side of the foil, so that the foil web passing between the first and second diverting elements over the third diverting element, which is capable of a springing motion, forms a bend that comprises a varying length of foil web.
In an embodiment of the apparatus, the sensor comprises a potentiometer so connected to the turning axle that the resistance of the potentiometer changes as a function of the angle of rotation of the turning axle, the angle being directly proportional to the tension of the foil web, to produce a control signal for controlling the speed and direction of rotation of the electric motor.
In an embodiment of the apparatus, the electric motor is a direct-current motor.
In an embodiment of the apparatus, the supporting elements for supporting the foil roll comprise a first supporting element, which is rotatably mounted with a bearing on the frame and fitted to support the foil roll from the side of its first end face, and a second supporting element, which is fitted to support the roller from the side of its second end face opposite to the first end face. The second supporting element comprises a drive shaft supported by a bearing on the frame. The drive shaft is driven by the electric motor.
In an embodiment of the apparatus, the apparatus has a first wheel, such as a belt pulley or the like, mounted on the drive shaft. Mounted on the shaft of the electric motor is a second wheel, such as a belt pulley or the like. A first endless traction means, such as a belt or the like, extends over the first and second wheels to transmit the power of the electric motor to the drive shaft.
In an embodiment of the apparatus, the apparatus has a third wheel, such as a belt pulley or the like, attached to the turning axle. Connected to the potentiometer is a fourth wheel. A second endless traction means, such as a belt or the like, extends the third and fourth wheels to transmit the rotation of the turning axle into rotation of the potentiometer.
In an embodiment of the apparatus, the wrapping apparatus comprises a machine frame supporting a wrapping ring arranged to guide the motion of the foil dispenser. The wrapping ring comprises two ring sections movable relative to each other between two positions. These positions are an open position, in which the ring sections have a port opening between them, and a closed position, in which the port opening is closed and the wrapping ring forms the endless ring-like track. The object to be packaged being a cylindrical body, such as a band roll, having a central hole going through it, the wrapping ring in its closed position has been arranged to pass through the central hole.
In an embodiment of the apparatus, the track is of a substantially elliptical form. The track comprises a straight track portion, which, in the closed position of the wrapping ring, passes through the hole in the object to be packaged and extends outside the hole to a distance from the end of the cylindrical object, and a curved portion which forms a curved track between the ends of the straight track portion and around the object to be packaged.
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patent: 195
Gerrity Stephen F.
Lowe Hauptman & Gilman & Berner LLP
Oy M. Haloila Ab
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