Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1999-12-23
2001-08-21
Sells, James (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S064000, C156S229000, C156S253000, C156S351000, C156S359000, C156S494000, C156S498000, C156S555000, C156S580200
Reexamination Certificate
active
06277224
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to an ultrasonic method and system for continuously perforating a continuous strip of material, and more particularly to an ultrasonic perforator and a method of performing an ultrasonic perforation.
BACKGROUND OF THE INVENTION
Perforations in continuous material are required in a variety of manufacturing processes. In particular, adhesive bandages are uncomfortable to the bandage user unless there are perforations through the bandages to allow access to some ambient air, called “breathing”. The number of perforations in the material, as well as the diameter of each perforation in the material, contribute to the air flow rate through material in cubic feet per minute per square foot. This air flow rate is referred to as porosity. Initially, mechanical punches were used to perforate the web of materials for adhesive bandages. Mechanical punches are limited to slower web speeds. Additionally, these punches required a great deal of maintenance for operation. The most crucial problem with the mechanical punches is the risk that the pins of the punches would break and lodge in the web, possibly injuring the bandage user.
Hot pin perforation is also known in the prior art. The limitations of hot pin perforation are numerous, including slow web speed, poor (non-circular) hole formation with raised rings of melted material around each hole, rough texture of the web due to the raised rings and the inefficient application of heat to the entire surface of the material. The results of hot pin perforations are marginal when foam is employed in the web.
Ultrasonic perforation is also employed in the prior art. The prior art ultrasonic systems employ ultrasonic equipment adjacent to a pin roll with a fixed gap of space in the path of the web between the ultrasonic equipment and the pin roll. This gap is created by the placement of a stop that limits movement of the ultrasonic equipment toward the pin roll. This fixed gap results in changes in the perforations over time due to the fact that the gap changes when the ultrasonic equipment is heated by use, and yields higher porosity as the temperature of the ultrasonic horn increases. The prior art also requires precise machining of the pin roll to an exact concentricity to avoid changes in the gap, and thus in the perforations, due to unevenness in the pin roll, and the repeated calibration of the ultrasonic equipment's position relative to the pin roll to maintain the fixed gap and thereby avoid changes in the perforations.
Thus, there exists a need for a web perforation system that offers high speeds, improved perforation quality control, and lower risk of injury to the ultimate user.
SUMMARY OF THE INVENTION
The invention has been developed for the perforation of a continuous web of materials in patterns, including custom designed patterns, with the advantages of high speed operation, well defined holes, smooth texture in the resulting perforated materials, the elimination of heating system problems, and a less expensive cost of operation.
The system includes a nip roll for providing tension to the web, a pin roll constructed of unhardened steel and a wear resistant coating, and an ultrasonic horn, which is cooled by a stream of forced air. The ultrasonic horn and pin roll are preferably positioned so that there is no gap between the two, and no calibration or extremely precise machining of the pin roll is required. The method of the invention includes holding the web in tension, perforating the web with ultrasonic equipment which is immediately adjacent to a pin roll, and cooling the ultrasonic equipment with a forced stream of air. The resulting material has well defined holes without abnormal tearing, and has a smooth surface with no raised annular edges around the holes.
The material to be perforated may have one or several compositions, such as wovens, non-wovens, or paper. A carrier construction web consists of an adhesive layer topped by a layer of film or foam and finally topped by carrier paper. An interliner construction web consists of a layer of film or foam topped by a layer of adhesive and finally topped by an interliner paper. The material may also be non-adhesive coated, non-laminated film or foam materials. These films, and the materials from which they are constructed, are well known in the art. Most preferably, the ultrasonic system for perforating a tensioned web having a top surface and a bottom surface includes a pin roll, having a plurality of perforators thereon, at least one ultrasonic emitter having an outlet that contacts and exerts a pressure on the tensioned web, at least one actuator that forces the ultrasonic emitter toward the tensioned web and maintains contact between the outlet and the tensioned web by exerting the pressure only on the tensioned web, and a nip roll that tangentially contacts the pin roll. The ultrasonic system for perforating a tensioned web may also include a forced air source that directs forced air onto the outlet, and a feedback controller that allows the outlet to reach a predetermined temperature, and then maintains that temperature by alternately activating and deactivating the forced air source.
REFERENCES:
patent: 4747895 (1988-05-01), Wallerstein et al.
patent: 5230761 (1993-07-01), Crawford
patent: 5735984 (1998-04-01), Hoff et al.
patent: 5879493 (1999-03-01), Johnson et al.
patent: 5879494 (1999-03-01), Hoff et al.
Adams Charles Lee
Chaney Angela
Kapalo Robert
Meizanis James
Muesch Edward
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