Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2000-11-30
2003-03-25
Sells, James (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S073100, C156S290000, C156S308400, C156S358000, C156S553000, C156S555000, C156S580200, C156S582000
Reexamination Certificate
active
06537401
ABSTRACT:
BACKGROUND
The present invention relates to apparatus and methods for effecting ultrasonic bonding on at least one web or workpiece (or discrete pieces on a workpiece segment or workpiece segments) using ultrasonic bonding apparatus. The invention more particularly concerns apparatus and methods for ultrasonically bonding at least one web or workpiece (or discrete pieces on a workpiece segment or workpiece segments) using rotary ultrasonic bonding apparatus.
Bond strength, where a rotary ultrasonic horn and a rotary anvil are used to bond workpiece segments (or discrete pieces on a workpiece segment or workpiece segments), is dependent on a variety of factors including horn frequency, horn amplitude, dwell time in the nip, and horn/anvil nip loading. More specifically, the consistency and quality of the bond when using such rotary bonding techniques is dependent on the consistency of the force exerted on the workpiece segment by the combination of the anvil roll and the ultrasonic horn: the time during which the workpiece segment is being pressed in the constrictive nip which is dependent on e.g. the operating speed: and the types of materials being bonded. The consistency and quality of the bonds are also dependent on the frequency and amplitude of the vibrations of the ultrasonic horn.
Consistency and quality of bonds when using conventional rotary ultrasonic bonding methods and apparatus have been particularly variable where the desired bond pattern is intermittent because the nip pressures inherently change in concert with the intermittent nature of the bonding operation.
Under excessive loading, so much energy may be applied to the materials being bonded as to burn through or otherwise excessively soften the materials being bonded, as well as to apply excessive pressure to the softened materials, whereby bonds so formed may be weak, and/or may be uncomfortably harsh to the touch of a wearer's skin. In the alternative, excessive loading can physically damage, as by tearing, the material being bonded. Additionally, excessive loading can increase wear and/or coin and thus damage the ultrasonic horn.
Early practice in the art of ultrasonic bonding was to force an anvil against a horn with a fixed, defined load. The anvil rode on the horn much like a train wheel runs on a rail. The force was constant regardless of the presence or absence of material in the horn/anvil nip. The constant force of the fixed load design at high force levels tended to cause rapid horn wear.
A step in the evolution of ultrasonic bonding was to load an anvil with high force against a fixed stop and to use the stop to set horn/anvil interference. In this design, the stop drew most of the load until material entered the horn/anvil nip; at that point, the greater interference caused by the material drew more of the load as the stop load diminished.
A need exists to develop a horn/anvil nip that can be loaded to a known force rather than a fixed interference. Similarly, a need subsists to develop horn/anvil loading apparatus which can produce a nip load reading representative of force in the nip rather than an inferred value based on theoretical interference.
It is an object of this invention to provide ultrasonic bonding apparatus and methods wherein horn/anvil nip pressure is more consistent along the lengths and widths of respective bonding regions.
It is another object of this invention to provide ultrasonic bonding apparatus and methods wherein force representative of force exerted at the horn/anvil nip can be detected and managed.
It is yet another object of this invention to provide ultrasonic bonding apparatus and methods wherein nip loading information is output from the ultrasonic bonding apparatus and is relayed to a display, therefore allowing an operator to manually or otherwise adjust the ultrasonic bonding apparatus to effect suitable bonding in the horn/anvil nip.
SUMMARY
In a first family of embodiments, the invention comprehends ultrasonic bonding apparatus for creating ultrasonic bonds in sequentially advancing absorbent article workplace segments, in a bonding nip. The ultrasonic bonding apparatus comprises a frame, anvil support apparatus, horn support apparatus, closure apparatus, a load cell support member, and a load cell. The anvil support apparatus defines an anvil loading assembly connected to the frame, and supporting an anvil roll having an operating width and a circumference, and mounted for rotation about a first axis. The horn support apparatus is connected to the frame, and supports a rotary ultrasonic horn mounted for rotation about a second axis, substantially aligned with the first axis. The ultrasonic horn and the anvil roll collectively are mounted and configured such that the ultrasonic horn and the anvil roll can be brought together to define the nip therebetween, wherein the anvil roll and the ultrasonic horn rotate in common with each other and with movement of workpiece segments through the nip. The closure apparatus is adapted to bring the anvil roll and the ultrasonic horn together to form the bonding nip. The load cell support member is connected to the frame, and the load cell is mounted to the load cell support member such that force representative of force exerted on the anvil roll at the nip can be detected by the load cell.
The apparatus preferably includes apparatus defining a limit to downward travel of the anvil roll.
In preferred embodiments, the second axis has an orientation parallel to the first axis.
In preferred embodiments, the frame, the anvil support apparatus, and the horn support apparatus collectively provide support structure sufficiently rigid that the horn and the anvil roll can be brought together with optional interference between the horn and the anvil roll of no more than about 0.003 inch in combination with defining sufficient nip pressure to develop ultrasonic bonds in absorbent article workpiece segments passing through the nip.
In some embodiments, a nip width, useful for applying forces to an absorbent article workpiece in the nip, can be defined between the ultrasonic horn and the anvil roll, wherein the anvil support apparatus preferably includes a resilient support member defining a resistance, to movement of the anvil roll away from the nip, of at least about 400 pounds per inch width of the nip.
The anvil support apparatus can further comprise one or both a lifting plate for lifting and lowering the anvil loading assembly with respect to the ultrasonic horn, and a pivot plate pivoting the anvil loading assembly about a third axis oriented perpendicular to the first axis.
In some embodiments, the ultrasonic bonding apparatus includes a back-up roll mounted for surface-to-surface relationship with the ultrasonic horn opposite the nip between the ultrasonic horn and the anvil roll, wherein the back-up roll engages an outer surface of the ultrasonic horn in alignment with extensions of the first and second axes.
In some embodiments, the ultrasonic bonding apparatus includes an adjusting device, operating on a cradle arm, for adjusting a height of the back-up roll, and thus generally defining an upper limit to movement of the ultrasonic horn.
In some embodiments, the ultrasonic bonding apparatus includes first and second support rolls releasably supporting opposing sides of an outer surface of the ultrasonic horn, an imaginary line connecting axes of the first and second support rolls passing vertically below the second axis.
In preferred embodiments, the anvil roll comprises a first relatively smaller radius portion extending about a first portion of a circumference of the anvil roll, and a raised bonding portion comprising a second relatively larger radius, extending about a second portion of the circumference of the anvil roll.
The second radius can be about 0.01 inch to about 0.07 inch larger than the first radius.
In some embodiments, the ultrasonic bonding apparatus includes drawing apparatus, adapted to draw the workpiece segments across the anvil roll, and thus through the nip defined between the anvil roll and the
Abel Kent William
Coenen Joseph Daniel
Couillard Jack Lee
Lohoff Michael Lee
Nason Robin Kurt
Kimberly--Clark Worldwide, Inc.
Sells James
Wilhelm Thomas D.
Wilhelm Law Service
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