Patent Application
20060005511
The present invention relates to a wrapping machine as defined in the preamble of claim 1. Moreover, the invention relates to a method as defined in the preamble of claim 6.
In prior art, specification U.S. Pat. No. 5,802,810 discloses a wrapping machine for wrapping a plastic foil web around an object to be packaged. The object to be wrapped is usually a load placed on a pallet, which typically is an assembly of the form of a rectangular parallelepiped.
U.S. Pat. No. 5,802,810 mainly describes a crank arm wrapping machine but, according to the specification, the special gripping and cutting device presented in it can also be applied in a ring-type wrapping machine. A ring-type wrapping machine usually has a machine frame supported on a fixed base and comprising a lifting frame which can be moved by a power means along upright vertical columns. A circular guide track is mounted on the lifting frame so as to be vertically movable with it. A film dispensing unit, on which a film web roll can be rotatably mounted, has been arranged to circulate along the circular guide track along a ring-like path around the object to be packaged to deliver plastic film web from the film web roll so as to form a wrapping around the object to be packaged.
U.S. Pat. No. 5,802,810 discloses a gripping and cutting device implemented with two swing arms, which is designed to replace an earlier gripping and hot seaming device, which at the end of the wrapping operation melts the film web onto the film web layer below by means of an electrically heated resistance wire and then cuts the film web beside the seaming line.
The function of the gripping and cutting device described in specification U.S. Pat. No. 5,802,810 is to hold the end of the film web at the start of the wrapping operation until it is caught between at least one film web layer and the object so that it will stay there. At the final stage of the wrapping operation, the gripping and cutting device is to terminate or cut the film web and leave the said end between at least one film web layer wrapped and the object. After that, the free end of the severed film web remains in the grip of the gripping and cutting device to be ready for the start of the next wrapping operation. This type of gripping and cutting device comprises a device frame. Further, the gripping and cutting device comprises a first swing arm, which is pivotally connected to the device frame via a first joint allowing a turning motion between a horizontal position and a vertical position. The first swing arm also comprises a first holding device for gripping and holding the film web. A second swing arm is pivotally connected to the device frame via a second joint disposed at a distance from the first joint and allowing a turning motion between a horizontal position and an upright position. The second swing arm comprises a second holding device for gripping and holding the constricted film web and a cutting device for culling the film web. This prior-art gripping and cuffing device is mounted on the device frame, which is supported on a fixed base, e.g. a floor, and is disposed in a wrapping station, where it can be moved to a position near the lower part of the object to be wrapped.
In itself, the above-mentioned swing-arm type gripping and cutting device has many advantages as compared with the prior-art gripping and seaming device that uses a melting technique. It comprises fewer moving parts and less control. In the device based on a melting technique, the resistance wire has to be supplied with an electric current to heat it, and on the other hand this heating has to be controlled. In the swing-arm type device, only the turning motion of the arms has to be controlled to make them turn at the right time. In addition, in the use of the swing-arm type device, the tension of the film web may vary, whereas for the operation of the seaming device using a melting technique it is necessary that that film web should be under a certain tension, i.e. not too tight and not too loose. It is therefore advantageous to use the swing-arm type gripping and cutting device because it is simpler in structure, requires less control and is not sensitive to variations in film tension.
However, the wrapping machine according to specification U.S. Pat. No. 5,802,810 involves the problem that, as the aforesaid gripping and cutting device implemented using swing arms is disposed near the lower part of the object to be wrapped, the wrapping action always has to be started from the lower part and finally ended at the lower part. Thus, wrapping is started from below, the film web is wrapped around the object in an ascending spiral form. After the object has been wrapped up to its top, more film web is then wrapped around the object in a descending spiral form to reach the lower part of the object again so that the film web can be terminated. Thus, when the prior-art device is used, the object always has to be wrapped twice over. Usually a single wrapping would be sufficient, so with the prior-art device an unnecessarily large amount of film web per object to be wrapped is consumed. In addition, double wrapping requires a long time. A further problem is that, with the prior-art wrapping machine, a so-called surface wrapping can only be made at the lower part of the object to be wrapped. Surface wrapping means that the film is not wrapped in spiral form but on a single given surface to form a ring-like collar around the object.
The object of the present invention is to overcome the above-mentioned drawbacks.
A specific object of the invention is to disclose a wrapping machine in which the wrapping action can be started and ended at any desired position in the vertical direction of the object to be wrapped.
The wrapping machine of the invention is characterized by what is disclosed in claim 1. The method of the invention is characterized by what is disclosed in claim 6.
The wrapping machine of the invention comprises
a machine frame supported on a fixed base and comprising vertical upright columns,
a lifting frame arranged to be moved upwards and downwards in a vertical direction while guided by the upright columns,
a power means for moving the lifting frame,
a circular guide track supported on the lifting frame so as to be vertically movable together with it,
a foil dispenser, on which a foil web roll can be rotatably mounted, said foil dispenser being arranged to circulate on a ring-like path, guided by the circular guide track, about the object to be packaged for delivering plastic foil web from the foil web roll to form a wrapping around the object to be packaged, and
a gripping and cutting device, which comprises a device frame, a first swing arm, connected to the device frame by a first joint so as to be turnable between a horizontal position and a vertical position, and said first swing arm comprising a first holding device for gripping and holding the foil web, and a cutting device for cutting the foil web, a second swing arm connected to the device frame by a second joint disposed at a distance from the first joint so as to be turnable between the horizontal position and the vertical position, said second swing arm comprising a second holding device for gripping and holding a constricted foil web.
According to the invention, the gripping and cutting device is coupled to the lifting frame so as to be vertically movable together with it.
The invention has the advantage that, being connected to the lifting frame moving upwards and downwards in a vertical direction, the gripping and cutting device can perform the starting and ending of the wrapping action at any vertical position relative to the object to be wrapped. It is possible to start the wrapping action from the upper part of the object, wrap the foil web spirally from the upper part of the object to its lower part and then terminate the foil web at the lower part of the object. Further, it is possible to start the wrapping action-from the lower part of the object, wrap the foil web spirally from the lower part of the object to its upper part and then terminate the foil web at the upper part of the object. Partial wrapping and collar wrapping are also possible. Collar wrapping can be performed at any level in the vertical direction of the object, at the lower part, around the middle part-or at the upper part.
In an embodiment of the wrapping machine, the wrapping machine comprises a crinkling device connected to the foil dispenser and having crinkling means for reducing the foil web delivered from the foil dispenser to a width narrower than full width. The holding devices have been fitted to grip the foil web constricted to a string-like form.
In an embodiment of the wrapping machine, the holding device comprises a dog placed at the end of a swing arm. Further, the holding device comprises a clutch guided by the swing arm so as to be movable towards and away from the dog for pressing the foil web constricted to a string-like form between the dog and the clutch. Moreover, the holding device comprises a power means for actuating the clutch.
In an embodiment of the wrapping machine, the cutting device comprised in the first swing arm comprises a cutting blade for severing the foil web constricted to a string-like form by cutting it apart.
In an embodiment of the wrapping machine, the lifting frame comprises substantially horizontal guide rails along which the device frame can be moved horizontally to move the gripping and cutting device towards and away from the object to be wrapped. Additionally a second power means is provided for moving the device frame.
In the method, a first swing arm, which has a first holding device holding the leading end of a foil web being delivered from a foil web roll, is placed in an upright position against the object to be wrapped. At least one layer of foil web is wrapped in substantially full width around the first swing arm and the object in such manner that at least part of the first swing arm remains between the wrapped foil web layer and the object. The end of the foil web is released from the first holding device. The first swing arm is turned to a horizontal position away from the position between the object and the foil web layer around the object. A desired amount of foil web is wrapped around the object while the first swing arm and a second swing arm are in a horizontal position. The second swing arm is set in an upright position close to the object. At least one foil web layer is wrapped around the second swing arm and the object in such manner that at least part of the second swing arm remains between the wrapped foil web layer and the object. The first swing arm is turned from the horizontal position to the upright position. The foil web is constricted by means of a crinkling device to a constricted string-like form and brought to a second holding device of the second swing arm and to the first holding device of the first swing arm, whereupon the string-like foil web is gripped by said holding devices. The foil web is severed by means of the cutting device of the first swing arm and the grip of the first and second holding devices on the string-like foil web is maintained further in such manner that the trailing end of the foil web wrapped around the object is in the grip of the second holding device and the foil web end drawn from the foil dispenser is in the grip of the first holding device, forming a leading end for a new wrapping operation. The second swing arm is removed from between the foil web layer and the object. The grip of the second holding device on the end of the foil web wrapped around the object is released and the grip of the first holding device on the leading end of the foil web being delivered from the foil dispenser is maintained.
According to the invention, the wrapping action is started from a freely chosen point relative to the vertical direction of the object to be wrapped and likewise ended at a freely chosen point relative to the vertical direction of the object to be wrapped.
In an embodiment of the method, the wrapping action is started from a point in or close to the upper part of the object to be wrapped and ended at a point in or close to the lower part of the object.
In an embodiment of the method, the wrapping action is started from the lower part of the object and ended at the upper part of the object.
In an embodiment of the method, the wrapping action is started from the middle area between the lower and upper parts of the object.
In an embodiment of the method, the wrapping action is ended at the lower part of the object.
In an embodiment of the method, the wrapping action is ended at the upper part of the object.
In an embodiment of the method, the wrapping action is ended at substantially the same height position as where it was started.
In the following, the invention will be described in detail with: reference to a few examples of its embodiments and the attached drawing, wherein
The wrapping machine 1 comprises a machine frame 1 supported on a fixed floor base. The machine frame comprises four vertical upright columns 2 at a distance from each other in a rectangular array so that each upright column 2 is situated at a different corner of the imaginary rectangular array. A lifting frame 3 has been arranged to be movable upwards and downwards along the upright columns 2 by means of a lifting motor 4 (see also
A foil dispenser 6, on which a foil web roll 7 can be rotatably mounted, has been arranged to circulate on a ring-like circular path along the circular guide track 5, about the object to be packaged so that the plastic foil web is delivered from the foil web roll 7 to form a wrapping around the object to be packaged. As the circular guide track 5 supporting the foil dispenser 6 is simultaneously moved vertically by moving the lifting frame 3, a spiral wrapping is formed around the object to be wrapped.
The preferred drive arrangement for the lifting frame 3 has been described in an earlier Finnish patent application FI 20030304 by the same applicant, to which reference is made here. It is obvious that the motion of the lifting frame 3 can be implemented by using any other suitable arrangement known in itself.
From
The lifting frame 3 is a substantially rectangular frame disposed horizontally within the area defined by the upright columns 2. The lifting frame 3 comprises two elongated, mutually parallel box-like lateral frame parts 33, 34, each extending horizontally between two upright columns 2. The drive belt pulley 31 is placed inside the box of the lateral frame part. As shown in
As shown in
The gripping and cutting device 11 comprises a device frame 12, which comprises an elongated beam 12 extending horizontally between the lifting frame 3 and the lateral frame parts 33, 34. Secured to the lateral frame parts 33, 34 are substantially horizontal guide rails 27, 27, along which the device frame 12 can be moved horizontally by means of a second power means 29, which is shown in
As is further shown in 3 and 4, the gripping and cutting device 11 comprises a first swing arm 13, which is pivoted on the device frame 12 by a first joint 14 so as to be turnable between a horizontal position I and an upright position II. For turning the first swing arm 13 between positions I and II, a power means 36, e.g. a pneumatic cylinder is provided. Placed at the free end of the first swing arm 13 is a first holding device 15 for gripping the foil web and holding it and a cutting device 16 for cutting the foil web. The cutting device 16 comprises a cutting blade 26 for severing the foil web reduced to a string-like form by a knife-like cutting action.
A second swing arm 17 is pivotally connected to the device frame 12 via a second joint 18 disposed at a distance from the first joint 14 so that the second swing arm 17 can turn between a horizontal position I and an upright position II. The second swing arm comprises a second holding device 19 for gripping and holding the constricted foil web and a cutting device for cutting the foil web.
The holding devices 15, 19 provided in the swing arms 13 and 17 have been fitted to grip the foil web constricted to a string-like form.
The wrapping machine further comprises a crinkling device 20 (see operational illustrations 5-22) connected-to the foil dispenser 6. The crinkling device 20 may be any known crinkling device by means of which the foil web delivered from the foil dispenser to the object can be constricted to a width narrower than full width, e.g. to a string-like form. Usually such a device comprises crinkling means 21, 22 movable towards and away from each other in the widthwise direction of the foil web, one of which crinkles the foil web from the lower edge while the other one crinkles the foil web from the upper edge. An advantageous crinkling device and its operation are described e.g. in Finnish patent application FI 20030421 by the same applicant, to which reference is made here. It is obvious that the crinkling device may also be any other suitable crinkling device known in itself.
Using the above-described wrapping machine, the wrapping action can be started from a freely chosen point on the object to be wrapped relative to its vertical direction, and similarly the wrapping action can be ended at a freely chosen point on the object to be wrapped relative to its vertical direction. Thus, wrapping can be started from the upper part of the object and ended at the upper part of the object. Likewise, wrapping can be started from the lower part of the object and ended at the upper part of the object. Furthermore, wrapping can be started from any desired point in the middle area of the object between the upper and lower parts, and ended at the upper or lower part of the object. Further, it is possible to start the wrapping action from any point and end it at the same point, i.e. to make a collar wrapping.
Referring to
The invention is not limited to the embodiment examples described above; instead, many variations are possible within the scope of the inventive concept defined in the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20030608 | Apr 2003 | FI | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10828229 | Apr 2004 | US |
| Child | 11174499 | Jul 2005 | US |
