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LASER DRILLING TECHNIQUE FOR SHAPED COOLING HOLES

IP.com Disclosure Number: IPCOM000248860D
Publication Date: 2017-Jan-18

Publishing Venue

The IP.com Prior Art Database

Abstract

A method for laser drilling shaped cooling holes involves rotating a substrate while pulsing a synchronized laser focused on the substrate. Multiple sequences of pulses can produce cooling holes having a metering section as well as a shaped diffuser section.

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LASER DRILLING TECHNIQUE FOR SHAPED COOLING HOLES

ABSTRACT

[0001] A method for laser drilling shaped cooling holes involves rotating a substrate

while pulsing a synchronized laser focused on the substrate. Multiple sequences of pulses

can produce cooling holes having a metering section as well as a shaped diffuser section.

BACKGROUND

[0002] This disclosure relates generally to methods for forming cooling holes, especially

in substrates such as gas turbine engine components.

[0003] Numerous components within a gas turbine engine are subject to high

temperatures and often require active cooling, in which pressurized cooling air is

discharged over a hot surface of the component through a plurality of cooling holes.

Combustor liners are one notable example of such a component.

[0004] A common type of cooling hole is a shaped cooling hole or "diffuser hole" which

incorporates a metering section (for example cylindrical) at an upstream end, and a

diffuser section of expanding flow area at a downstream end. Diffuser holes are known to

improve film cooling efficiency by spreading out the cooling film over the component

surface area and reducing flow velocity so as to prevent film blow-off from the

component surface.

[0005] It is known to form cylindrical cooling holes using laser drilling techniques.

[0006] It is also known to form cylindrical cooling holes using a technique referred to as

" laser drilling on the fly". This technique involves rotating the cylindrical component in

a fixture while pulsing a laser aimed in a radial direction at the component. The laser

pulses are synchronized to the rotation of the cylindrical component. One laser pulse is

fired at each hole once per revolution. Generally, multiple pulses are be required to pierce

the cooling hole completely through the thickness of the component.

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[0007] It is further known to form shaped cooling holes using laser drilling techniques,

however this typically involves a great deal of time and machine movements as the

diffuser portion of each cooling hole is individually formed by repeatedly moving the

laser relative to the component and pulsing the laser.

[0008] Described herein is a method of laser drilling diffuser holes in a combustor liner

or other similar component using laser drilling on the fly.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The concept may be best understood by reference to the following description

taken in conjunction with the accompanying drawing figures in which:

[0010] FIG. 1 is a schematic cross-sectional view of a portion of the substrate having a

shaped cooling hole formed therein;

[0011] FIG. 2 is a view taken along lines 2-2 of FIG. 1;

[0012] FIG. 3 is a schematic perspective view of a substrate mounted in an apparatus for

laser drilling shaped cooling holes;

[0013] FIG. 4 is a flowchart depicting a laser drilling method; and

[0014] FIG. 5 is a schematic sectional view of a shaped cooling hole being formed using

the method shown in FIG. 4.

DETAILED...