Plastic and nonmetallic article shaping or treating: processes – Direct application of electrical or wave energy to work – Using sonic – supersonic – or ultrasonic energy
Reexamination Certificate
1999-02-03
2001-02-20
Silbaugh, Jan H. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Direct application of electrical or wave energy to work
Using sonic, supersonic, or ultrasonic energy
C264S156000, C156S303100, C425S290000, C425SDIG003, C083S660000, C083S698420
Reexamination Certificate
active
06190602
ABSTRACT:
FIELD OF INVENTION
This invention relates to a method of manufacturing a perforated laminate useful, for example, as a part of a Helmholtz resonator structure.
BACKGROUND OF INVENTION
Perforated laminate sheets are used in a variety of application including Helmholtz resonators which include a honeycomb core supporting a perforated laminate face sheet. Such structures are used to form the arcuate inner surfaces of the nose cowl and thrust reverser components of a nacelle system of a commercial jet aircraft.
Surprisingly, perforating a composite laminate is not a straight forward process. The problems with drilling, abrasion, stamping, water jet, laser beam, and other similar processes are documented in U.S. Pat. Nos. 5,268,055 and 5,252,279 incorporated herein by this reference.
So, these and other patents (e.g., U.S. Pat. Nos. 4,541,879; 4,390,584; 5,419,865; 4,612,737; and 4,486,372) delineate a different perforation methodology wherein a pin mat is used to perforate the composite laminate. The pin mat is formed from a plate with a number of interconnected, integral, upstanding pins or studs. A number of these pin mats are interlocked and a laminate, usually in the prepreg stage, is driven onto the pin mat using pressure or some kind of an impacting tool.
The primary limitation with this manufacturing method is the extremely high number of man hours required to fabricate the pin mats, assemble them on a forming tool, form the perforated composite laminate sheet, and to then re-work the perforations due to the fact that a number of pins usually break off from the pin mat during processing. Another limitation is that since the pins of the pin mat must be extracted from the perforated laminate in the same direction they were inserted, the pins must have a conical shape resulting in tapered perforations which are not as beneficial as straight perforations. Moreover, extruded pin mats, typically only available in 27″×43″ sheets, require heat treating and theremoforming before use.
SUMMARY OF INVENTION
It is therefore an object of this invention to provide an improved method of manufacturing a perforated laminate.
It is a further object of this invention to provide such a method which dramatically reduces the number of man hours required to manufacture a perforate laminate.
It is a further object of this invention to provide such a method which requires little rework.
It is a further object of this invention to provide such a method which results in a higher quality perforated laminate.
It is a further object of this invention to provide such a method which results in a perforated laminate having perforations which are straight instead of tapered.
It is a further object of this invention to provide such a method which results in lower cost perforated laminate sheets useful in a variety of applications.
It is a further object of this invention to provide such a method which is easy to implement and simple to understand.
It is a further object of this invention to provide a perforated laminate sheet manufactured in accordance with the novel method of this invention.
This invention results from the realization that a higher quality and lower cost perforated laminate useful for Helmholtz resonator and other structures can be manufactured, not by using a pin mat and driving the laminate onto the pin mat, but instead by keeping the laminate stationary and then driving a number of discrete pins through the stationary laminate using discrete pins supported as they are driven into the laminate by, for example, a pliable body which is much easier to manipulate and conform to the contours of the resulting laminate than the prior art pin mats which are difficult to manufacture in the first place and also difficult to work with. By using the discrete pins instead of the pin mats, straight shaft pins can be used resulting in better formed perforations. In addition, the pins are easier to remove from the perforated laminate as compared to the broken off truncated, conical shaped pins of the prior art pin mat based manufacturing methods. Since the pin mat itself is eliminated in this invention, the problems and high number of man-hours associated with fabricating and forming the pin mats and orienting them on the forming tool are eliminated.
This invention features a method of making a perforated laminate, the method comprising assembling a pliable perforation device having a plurality of holes and a plurality of perforation pins in the holes on a laminate, driving the pins through the laminate to perforate the laminate, and removing the pins from the laminate.
The perforation device typically includes a body of cured silicone material and may have one or more layers of laminate material. The pins are preferably sharpened on at least one end.
An ultrasonic horn may be used to engage a number of the perforation pins and drive them in unison into the laminate.
The laminate is typically a prepreg material and the method further includes the step of staging or curing the laminate after the pins are driven through the laminate but before the pins are removed from the laminate. To drive the pins through the laminate, the laminate is placed on a backing material which resides on a support tool. The support tool may be curved.
Removing the pins may include removing the backing layer from the laminate and pushing the pins flush with one surface of the laminate and back through the holes in the perforation device. The perforation device is then stripped away from the perforated component. Then, the pins may be pushed flush with one surface of the perforation device in order to reuse the perforation device.
This invention also features a perforated laminate made in accordance with this method.
This invention further features a reusable perforation device for making a perforating laminate, the perforation device comprising a pliable body including a plurality of holes therethrough, and a plurality of perforation pins positioned in the holes of the pliable body along at least a portion of their lengths, the pins extending above one surface of the pliable body.
The pliable body preferably has a bending strength much less than its compressive strength. The pliable body may include a sheet of cured silicone material and may include one or more layers of laminate material.
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Blaney Eric
Freitas Glenn A.
Fusco Thomas M.
Rich David
Aztex, Inc.
Iandiorio & Teska
Silbaugh Jan H.
Staicovici Stefan
LandOfFree
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