Winding – tensioning – or guiding – Convolute winding of material – Of discrete sheets or articles
Reexamination Certificate
2001-08-03
2004-07-13
Jillions, John M. (Department: 3654)
Winding, tensioning, or guiding
Convolute winding of material
Of discrete sheets or articles
C242S531100, C242S532000, C242S547000, C242S571100
Reexamination Certificate
active
06761329
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the art of winding equipment. More specifically, the invention relates to an apparatus and a method of producing rolls of plastic bags, in which the bags are wound into a roll without being connected to one another. The invention also concerns a winding station.
DESCRIPTION OF THE PRIOR ART
Many different types of winding machines are known for winding pliable strips of material such as plastic bags. One type of apparatus is arranged to wind bags into a roll without the bags being connected to one another. In this apparatus, a bag is separated from a continuous web of bag material having transverse lines of perforations in the boundary between adjacent bags. A leading end of the separated bag is arranged to overlap a trailing end of a preceding bag, thereby building a strand of so-called interleaved bags. This strand of bags is then wound into a roll in a winding device.
A roll-forming apparatus of this kind, disclosed in U.S. Pat. No. 5,377,929, has a tumbler assembly, which is arranged between a feeding device and a winding device. The tumbler device is adapted to receive a continuous web of bag material from the feeding device. By rotation of the tumbler assembly, a bag is separated from the web and arranged to partly overlap a trailing end of the succeeding web fed from the feeding device. The strand of interleaved bags thus formed is fed to the winding device, in which a roll of bags is formed.
U.S. Pat. No. 4,000,864 discloses a roll-forming apparatus in which a gripping device is arranged between a feeding device and a winding device. The gripping device is adapted to grip the leading edge of a separated bag as received from the feeding device, accelerate the separated bag relative to a preceding bag, decelerate the separated bag and place a leading end of the separated bag on a trailing end of the preceding bag. This operation is repeated to form a strand of interleaved bags, which are fed to the winding device.
U.S. Pat. No. 4,034,928 discloses a roll-forming apparatus having a sheet tuck-in means in the form of a blade. In this apparatus, separate bags are fed to the tuck-in means, where a bag is folded by advancing the blade into contact with the bag about midway between its terminal edges. Then a succeeding bag is fed to the tuck-in means, folded and advanced such that it is caught between the terminal edges of the preceding bag. Thus, a strand of interleaved bags is created. This strand is fed to a winding device, in which a roll of bags is formed.
One drawback of the above types of apparatus resides in their inherent mechanical complexity. Thus, the prior-art roll-forming apparatus tend to be expensive, have much down-time and require frequent maintenance. Further, the apparatus often include sophisticated control systems for adequate timing of the feeding and overlapping operations. Expensive and delicate sensors might also be installed to provide the necessary timing signals. Also, the overlapping operation often calls for a periodic and abrupt change in the speed of various feeding mechanisms, leading to increased wear and tear in the machinery.
Further prior art is disclosed in U.S. Pat. No. 5,779,180, WO 97/33744 and DE-A-37 42 994, the latter disclosing a device for producing a stack of plastic bags. The stacking device includes a rotating barrel drum, the periphery of which has a projecting needle. Separated bags are sequentially fed to the barrel drum, where they are threaded onto the projecting needle, thereby creating a stack of overlapping bags on the periphery of the drum. By stopping the drum and retracting the needle, the stack of bags can be transferred to a subsequent discharge device.
In U.S. Pat. No. 4,757,952, a winding device is disclosed in which an endlessly rotating belt is used to feed bags onto a winding core where they are wound into a roll.
All of the above-mentioned winding devices suffer from the disadvantage of having to be stopped for removal of a completed roll of bags before winding of a new roll can begin. This causes interruptions in the production, which, in turn, cause increased costs.
OBJECTS OF THE INVENTION
One object of the invention is to solve or alleviate some or all of the above problems associated with prior art. More specifically, it is an object of the invention to provide a roll-forming apparatus of simple structure, which is capable of winding bags into a roll without the bags being connected to one another and without inflicting any damage to the bags.
Furthermore, the apparatus should cause low wear and tear to the included components.
A further object is to provide a roll-forming apparatus with little need for control and timing in the production of rolls of bags.
Still another object is to provide an apparatus allowing little down-time and high production rates.
An additional object of the invention is to provide an apparatus capable of being included in or operated together with conventional bag-making machines.
A specific object is to provide a new winding station, which is improved over prior art.
Another object of the invention is to provide a method of producing rolls of bags, remedying some or all of the drawbacks discussed above.
SUMMARY OF THE INVENTION
These and other objects and advantages of the invention, which will appear from the description below, are achieved by an apparatus, a winding station and a method as set forth in the independent claims, preferred embodiments and variants being defined in the dependent claims.
The invention is based on the understanding that it is possible to dispense with the arranging of the separated bags in an overlapping fashion before winding them into a roll of bags. Instead, the feeding means is arranged to feed bags one by one to the winding stations. Each winding station includes a rotating spindle, which is arranged to engage with each bag, directly or via bags previously wound thereon, to form the roll of bags in which the bags are unconnected to one another yet firmly held together. This allows a considerably simplified construction of the apparatus. Since the bags are fed one by one to the winding stations, there is no need for tumbling or reciprocating devices manipulating the leading or trailing ends of each bag. This results in a reduced risk of damage to the bags, as well as low wear and tear in the construction itself. Further, since the bags are fed one by one to the winding stations, it is easy to direct the flow of separate bags between different winding stations. This allows high production rates since two or more winding stations can be operated sequentially such that a roll of bags is being formed in one winding station while a finished roll of bags is being discharged from an adjacent winding station.
The apparatus preferably comprises a separation device arranged to separate the bags from a continuous web of bag material with perforations in the boundary between adjacent bags. This provides a rational manner of feeding separate bags to the apparatus.
In one embodiment of the apparatus the separation device includes a first driven pair of rollers for feeding the web, and an engagement means which is arranged upstream of the first pair of rollers, in the feeding direction. The engagement means is operable to engage the web at least intermittently to thereby separate a bag therefrom. This is a practical way of separating bags from the web.
The distance between the engagement means and the first pair of rollers is preferably adjustable to exceed the mutual distance between successive perforations in the web. This provides the possibility of adjusting the separation device to different bag lengths.
The engagement means may include a second driven pair of rollers for feeding the web. In such case, the feeding rate of the first pair of rollers should exceed the web feeding rate of the second pair of rollers. As a result, bags may be separated from the web of bag material without any interruption in the web feeding.
The feeding means of the apparatus according to the invention preferably compris
Bartels Willy
Darvas Zoltan
Hallin Per Anders
Holm Thomas
Leijon Thomas
FAS Converting Machinery AB
Jillions John M.
Smith Gambrell & Russell
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