Electric heating – Metal heating – By arc
Reexamination Certificate
1999-04-08
2001-03-27
Ryan, Patrick (Department: 1725)
Electric heating
Metal heating
By arc
C219S121640, C219S121770, C219S121670, C219S121720, C219S121830, C053S170000
Reexamination Certificate
active
06207925
ABSTRACT:
TECHNICAL FIELD
This invention relates to a method and apparatus for welding and/or cutting flexible packaging material using lasers.
BACKGROUND
Welding and cutting of plastics film or foil is particularly important with flexible packaging equipment, for example in the bag making industry, and also in form/fill/seal machinery.
There are three main methods for welding plastics film or foil utilised in packaging machinery. These are hot metal welding, radio frequency welding and ultrasonic welding.
All three of these methods have the disadvantage of requiring mechanical contact between the substrate to be welded and the cutting equipment. Mechanical contact can result in substrate sticking to the sealing/cutting equipment, and requires blades or the like which need regular sharpening, replacement, cleaning and maintenance. These known methods and apparatus are also mechanically complex.
Furthermore, machinery employing these methods requires a stop/start cycle, the stop component necessary to allow time for the mechanical contact between the welding head and the substrate to produce the required weld. Alternatively, the welding head may move with the substrate, but this requires multiple welding heads in order to achieve an acceptable processing speed. The requirement for multiple welding heads further adds to the mechanical complexity of the equipment.
Another difficulty associated with existing equipment employing welding heads is that some plastics materials are difficult to seal, and it may be impractical to weld thick gauge substrates, to weld plastic to metal foil, or to weld temperature-resistant materials.
Moreover, with hot metal, radio frequency and ultrasonic welding the focusing of heat may be poorly controlled making it difficult to weld or seal shrink film, for example. In addition, these conventional systems may require ramping in of dwell time and preheating of sealing mechanisms which add to their complexity. If they don't have such features then there are inefficiencies associated with scrap substrate.
Lasers are employed in the packaging industry in various capacities, including for producing score lines on plastics packaging material to facilitate opening of such packaging, and for cutting out and welding customised shapes of bags made of fluorocarbon materials. However, where such laser technology has been employed it has not generally been adapted for use in association with highspeed packaging machinery, In particular, the laser beams have been fixed, for the production of welds, seals or score lines in a longitudinal direction along a moving film, or means of lateral scanning have been inefficient, of limited lateral span and/or not designed for use with continuously moving webs or films of material.
Thus, it is an object of the present invention to provide a method and apparatus for welding and/or cutting flexible packaging material in motion, employing lasers which overcomes or reduces the above-mentioned problems, or which at least provides the public with a useful alternative.
Other objects of the present invention may become apparent from the following description which is given by way of example only.
DISCLOSURE OF INVENTION
According to one aspect of the present invention there is provided a method of cutting and/or welding flexible packaging material in motion, said method comprising:
feeding a substrate comprising two or more layers of flexible packaging material through an operational site, contacting adjacent layers of the material at said operational site,
focusing one or more processing laser beams on said substrate at said operational site,
scanning the or each processing laser beam on said moving substrate, by scanning means, to produce one or more cuts and/or welds in said substrate, and
controlling the relationship between the rate of scanning and the rate of motion of the substrate to produce the one or more required cuts and/or welds.
In one preferred method of the invention the scanning may comprise directing the or each processing laser beam at a scanning mirror and pivoting said mirror to produce the required scan of the beam on the moving substrate.
Preferably, there may be a plurality of processing laser beams and scanning means each scanning means adapted to scan a processing laser beam on a different part of the substrate so that each scan overlaps or interconnects with the or each adjacent scan.
In a further preferred form, the method of the present invention may further comprise dividing the or each processing laser beam into at least two sub-beams, realigning said sub-beams, and separately focusing each sub-beam.
Preferably, the or each processing laser beam may be divided into three sub-beams, one forming a central cutting beam and the other two forming lateral welding beams.
Preferably, the method may further comprise interrupting, permanently or intermittently, one or more sub-beam.
In one preferred form, said method may further comprise modifying the power density of the or each processing laser beam and/or sub-beam.
Preferably, the rate of scanning in relation to the rate of motion of substrate may be adjustable during scanning to enable cuts/welds of predetermined shape to be made.
Preferably, the method may further comprise monitoring the progress of a substrate to correlate scanning with the location of indicators on the substrate.
According to a further aspect of the present invention there is provided apparatus for cutting and/or welding flexible packaging material in motion, said apparatus comprising:
feeding means adapted to feed a substrate comprising two or more layers of flexible packaging material through an operational site,
contacting means adapted to produce intimate contact between adjacent layers of the substrate at said operational site,
one or more lasers, adapted to produce one or more processing laser beams,
focusing means adapted to focus the one or more processing laser beams on said substrate at the operational site,
scanning means adapted to scan the one or more processing laser beams on the moving substrate to produce one or more cuts and/or welds in said substrate, and
control means adapted to control the relationship between the rate of scanning and the rate of motion of the substrate to produce one or more required cuts and/or welds.
Preferably, there may be a plurality of scanning means each adapted to scan a part of the substrate so that each scan overlaps or interconnects with the or each adjacent scan.
In one preferred form of apparatus of the present invention the or each scanning means may comprise a scanning mirror and a scanning motor, said scanning motor adapted to pivot said mirror causing a beam or beams reflected by the mirror to traverse at least a part of the substrate.
In such a preferred form there may be two processing laser beams simultaneously and/or alternately scanned on different parts of the moving substrate by alternate scanning means.
In a further preferred form said apparatus may further comprise dividing means adapted to divide the or each processing laser beam into at least two sub-beams. Preferably, said apparatus may further comprise realignment means adapted to realign said sub-beams to an adjacent relationship.
In one preferred form, said dividing means may divide the or each processing laser beam into three sub-beams.
Preferably, said focusing means may be adapted to separately focus each sub-beam.
In a further preferred form the apparatus of the present invention may further comprise interrupting means, adapted to interrupt the or each processing beam and/or sub-beam.
Preferably, the control means may enable variable control of the rate of scanning such that the cuts/welds may be straight or curved.
Preferably, the control means may further comprise monitoring means adapted to monitor progress of the substrate to correlate scanning with the location of indicators on the substrate.
Other aspects of the present invention may become apparent from the following description which is given by way of example only and with reference to the accompanying drawing.
Cooke Colleen
Ryan Patrick
Scully Scott Murphy & Presser
LandOfFree
Apparatus for cutting and/or welding flexible packaging does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus for cutting and/or welding flexible packaging, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for cutting and/or welding flexible packaging will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2489164