Methods of ultrasonic drilling for forming perforations in composite materials
AssigneeThe Boeing Company
InventorWeidong Song
Life of this patent
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Abstract
Methods of ultrasonic drilling may be used to form perforated sheets by forming holes through a workpiece using a needle or needle array operatively coupled to an ultrasonic actuator. The needle is brought to repeatedly contact the surface of the workpiece at an ultrasonic operating frequency, thereby forming the hole through the workpiece. Such steps are repeated to form a plurality of holes in the workpiece, thereby forming a perforated sheet which may be used in an acoustic liner for noise attenuation. The workpiece may be heated while the holes are formed, via a remote heating unit that locally heats a portion of the workpiece.
Claims20
A method of performing ultrasonic drilling to form a hole in a workpiece at a first location of the workpiece, the method comprising:
- positioning a surface of the workpiece with respect to a tool of an ultrasonic hone, wherein the tool has a longitudinal axis that is substantially orthogonal to the surface of the workpiece;
- and
- forming the hole in the workpiece by vibrating the tool along the longitudinal axis such that the tool repeatedly contacts the surface of the workpiece at an operating frequency and amplitude sufficient to form the hole in the workpiece, wherein the vibrating the tool is performed for a time sufficient to form the hole in the workpiece, wherein the tool is not rotated with respect to the surface of the workpiece during the forming the hole, wherein the forming the hole is performed without use of a slurry or a cooling fluid, and wherein the workpiece is composed of a composite material.
A method of forming a plurality of perforations in a thin sheet of a composite material, the method comprising:
- positioning a surface of the thin sheet and a needle array operatively coupled to an ultrasonic hone such that the needle array is positioned above a first region of the thin sheet, wherein the needle array comprises a plurality of needles extending along a longitudinal axis that is substantially orthogonal to the surface of the thin sheet;
- repeatedly contacting the surface of the thin sheet material within the first region with the needle array at an operating frequency of above 20 kHz for a first period of time that is sufficient to form a first plurality of holes in the first region of the thin sheet, wherein the repeatedly contacting the surface of the thin sheet forms a respective first hole in the thin sheet corresponding to each respective needle of the needle array, wherein the repeatedly contacting the surface of the thin sheet comprises contacting the thin sheet with the plurality of needles of the needle array without rotating the plurality of needles about the longitudinal axis, without rotating the plurality of needles with respect to the thin sheet, and without use of a slurry or a cooling fluid;
- translating the needle array with respect to the thin sheet such that the needle array is positioned above a second region of the thin sheet;
- and
- repeatedly contacting the surface of the thin sheet within the second region with the needle array at the operating frequency for a second period of time that is sufficient to form a second plurality of holes in the second region of the thin sheet, wherein the repeatedly contacting the surface of the thin sheet forms a respective second hole in the thin sheet corresponding to each respective needle of the needle array, wherein the repeatedly contacting the surface of the thin sheet comprises contacting the thin sheet with the plurality of needles of the needle array without rotating the plurality of needles about the longitudinal axis, without rotating the plurality of needles with respect to the thin sheet, and without use of the slurry or the cooling fluid.
An acoustic liner, comprising:
- a thin sheet material composed of a carbon-fiber reinforced polymer and including at least 100,000 non-circular perforations formed through a thickness of the thin sheet material;
- a honeycomb structure having a first side, a second side opposite the first side, and a plurality of internal cells extending between the first side and the second side, wherein the first side is coupled to the thin sheet material, and wherein each internal cell of the plurality of internal cells is sized to fit an acoustic plane wave in the internal cell for a desired frequency range such that the acoustic liner is configured to produce noise attenuation properties for the desired frequency range;
- and
- a rigid backplate coupled to the second side of the honeycomb structure.
Dependencies are inferred from the claim text.