GB2236070A - Laser barrier material - Google Patents
Laser barrier material Download PDFInfo
- Publication number
- GB2236070A GB2236070A GB9020561A GB9020561A GB2236070A GB 2236070 A GB2236070 A GB 2236070A GB 9020561 A GB9020561 A GB 9020561A GB 9020561 A GB9020561 A GB 9020561A GB 2236070 A GB2236070 A GB 2236070A
- Authority
- GB
- United Kingdom
- Prior art keywords
- component
- copolymer
- ptfe
- barrier material
- cavity
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/224—Anti-weld compositions; Braze stop-off compositions
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/18—Working by laser beam, e.g. welding, cutting or boring using absorbing layers on the workpiece, e.g. for marking or protecting purposes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/36—Removing material
- B23K26/38—Removing material by boring or cutting
- B23K26/382—Removing material by boring or cutting by boring
- B23K26/389—Removing material by boring or cutting by boring of fluid openings, e.g. nozzles, jets
Abstract
In the laser drilling of a hole through a wall of a gas turbine blade into a cavity within the blade there is provided an injectable PTFE substitute for injection into the cavity before laser drilling. The PTFE substitute prevents strike-through of laser light to the opposite wall of the cavity. The PTFE substitute used is fluorinated ethylene propylene or a copolymer having a PTFE backbone and fully fluorinated alkoxy side groups. <IMAGE>
Description
LASER BARRIER MATERIAL
This invention relates to laser drilling of components, particularly, although not exclusively, the drilling of holes in gas turbine components such as hollow turbine blades.
The laser drilling of holes such as film-cooling holes into internal passages of turbine blades has been known for some time. However, a problem that commonly arises is that of preventing the laser beam from damaging the wall of the passage opposite to where the laser beam breaks through. Another problem that arises is that of preventing material sputtered or vaporised by the beam from being deposited on the inner surfaces of the passage.
Attempts have been made to insert barriers in the passages, and indeed in passages or cavities which are relatively large and do not have complicated shapes it is possible to insert a solid piece of barrier material such as polytetrafluoroethylene (PTFE), which particular material has excellent laser barrier properties.
However, it may be difficult or Impossible to insert a piece of barrier material into a passage or cavity which is convoluted or too small. In these instances it is common practice to inject or pour a thermosetting fluid, such as wax, into the passage or cavity. Wax has disadvantages in some circumstances, in that it does not always provide the required protection against strike-through, especially when passages are of small dimensions, and tends to solidify before the passage or cavity is completely filled. PTFE, as mentioned above, provides the required barrier properties against laser light but cannot be injected or poured.
It is an object of the present invention to provide a substitute for PTFE which has similar resistance to strike-through as PTFE but is capable of being injected into a cavity.
According to a first aspect of the present invention there is provided an injectable barrier material for use in laser machining of a component to protect a surface of the component which is in the path of a laser beam from being machined by the laser beam, the material comprising a composition selected from the group consisting of a first copolymer of tetrafluoroethylene and hexafluoropropylene and a second copolymer having a PTFE backbone and at least one fluorinated alkoxy side group.
According to a second aspect of the present invention there is provided a method of drilling a hole through a wall of a hollow component by means of a laser beam into the interior of the component so as to protect an interior surface of the component from being machined by the beam, comprising melting a composition selected from the group consisting of a first copolymer of tetrafluoroethylene and hexafluoropropylene and a second copolymer having a PTFE backbone and at least one fluorinated alkoxy side group, pouring or injecting the molten composition Into the interior of the component, permitting the molten composition to solidify, drilling the hole through the wall by means of the laser beam, the energy of the beam being dissipated by the solidified composition within the component, and subsequently steaming out the composition.
The invention will now be described by way of example only with reference to the following examples and the accompanying diagrammatic Figure 1 which shows a transverse section througha hollow turbine blade.
Referring to Figure 1 there is shown in transverse section a gas turbine blade 10 having internal longitudinally extending cavities 12, 14. There is provided a laser source 16 to drill a film-cooling hole 18 through to one of the cavities (eg. cavity 12 as shown) by means of a laser beam 20.
Example 1
Prior to the drilling of hole 18 into cavity 12 in the gas turbine blade 10, a flurocarbon resin barrier material comprising TEFLON PFA - a Trade Mark of E. I. du Pont de
Nemours & Co. (Inc.) -being a copolymer consisting of a PTFE backbone and fully fluorinated alkoxy side groups described in "Properties Handbook of TEFLON PFA Resins for Design Engineers" published by Du Pont under their reference E-84055, is heated to its melting point of 302-310 OC, injected in its molten state into the cavity 12 from one end of the blade, and is allowed to cool and solidify.It is found, on using the laser to drill hole 18 into the barrier-filled cavity 12, that the TEFLON PFA provides an effective barrier against laser light similar to that provided by PTFE on its own, by dissipating the energy of the laser beam, thus preventing strike-through of laser light to the opposite wall of the cavity. When the desired number of air-cooling holes has been drilled in the blade the PFA barrier material is steamed out of the cavity 12.
Example 2
Prior to the drilling of hole 18 into cavity 12 in the gas turbine blade 10, a fluorocarbon resin barrier material comprising TEFLON FEP - a Trade Mark of E. I. du Pont de
Nemours & Co. (Inc.) - being a copolymer of tetrafluoroethylene and hexafluoropropylene described in Du
Pont's Product Information pamphlet entitled "TEFLON FEP" published under their reference E-96223, is heated to its melting point of 255 0C, injected into the cavity 12 from one end of the blade, and is allowed to cool and solidify. It is found, on using the laser to drill hole 18 into the barrier-filled cavity 12, that the TEFLON FEP provides an effective barrier against laser light similar to that provided by PTFE on its own, by dissipating the energy of the laser beam, thus preventing strike-through of laser light to the opposite wall of the cavity. When the desired number of air-cooling holes has been drilled in the blade the FEP is steamed out of the cavity 12.
The TEFLON PFA and TEFLON FEP have the advantages of PTFE in providing an effective barrier against laser light, but have the advantage over PTFE in that they can be injected or poured, unlike PTFE.
The PFA copolymer need not have all its alkoxy side groups fully fluorinated, as long as there is sufficient fluorine in the molecule to provide the required stability and resistance to laser strike-through whilst retaining the features that it can be injected into the cavity, solidifies whilst in the cavity, and is easily removed by, for example, steaming.
Claims (7)
1. An injectable barrier material for use in laser machining of a component to protect a surface of the component which is in the path of a laser beam from being machined by the laser beam, the material comprising a composition selected from the group consisting of a first copolymer of tetrafluoroethylene and hexafluoropropylene and a second copolymer having a PTFE backbone and at least one fluorinated alkoxy side group.
2. A barrier material as claimed in claim 1 wherein the second copolymer has a plurality of fluorinated alkoxy side groups.
3. A barrier material as claimed in claim 1 wherein the at least one alkoxy side group is fully fluorinated.
4. A barrier material as claimed in claim 4 wherein all the alkoxy side groups of the second copolymer are fully fluorinated.
5. A method of drilling a hole through a wall of a hollow component by means of a laser beam into the interior of the component so as to protect an interior surface of the component from being machined by the beam, comprising melting a composition selected from the group consisting of a first copolymer of tetrafluoroethylene and hexafluoropropylene and a second copolymer having a PTFE backbone and at least one fluorinated alkoxy side group, pouring or injecting the molten composition into the interior of the component, permitting the molten composition to solidify, drilling the hole through the wall by means of the laser beam, the energy of the beam being dissipated by the solidified composition within the component, and subsequently steaming out the composition.
6. An injectable barrier material substantially as hereinbefore described with reference to Example 1 or Example 2, together with the accompanying drawing.
7. A method of drilling a hole through a wall of a hollow component into the interior of the component, susbtantially as hereinbefore described with reference to Example 1 or Example 2, together with the accompanying drawing.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB898921288A GB8921288D0 (en) | 1989-09-20 | 1989-09-20 | Laser barrier material |
Publications (3)
Publication Number | Publication Date |
---|---|
GB9020561D0 GB9020561D0 (en) | 1990-10-31 |
GB2236070A true GB2236070A (en) | 1991-03-27 |
GB2236070B GB2236070B (en) | 1993-06-09 |
Family
ID=10663378
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB898921288A Pending GB8921288D0 (en) | 1989-09-20 | 1989-09-20 | Laser barrier material |
GB9020561A Expired - Fee Related GB2236070B (en) | 1989-09-20 | 1990-09-20 | Laser barrier material |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB898921288A Pending GB8921288D0 (en) | 1989-09-20 | 1989-09-20 | Laser barrier material |
Country Status (1)
Country | Link |
---|---|
GB (2) | GB8921288D0 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2699844A1 (en) * | 1992-12-30 | 1994-07-01 | Snecma | Method and device for laser beam machining |
US6407362B1 (en) * | 1998-07-22 | 2002-06-18 | Hydraulik-Ring Gmbh | Protective device for producing very small bores in tubular components, and method for producing bores |
WO2016055345A1 (en) * | 2014-10-09 | 2016-04-14 | Siemens Aktiengesellschaft | Method for producing through-holes in a wall of a component, by means of laser radiation |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1228438A (en) * | 1964-11-23 | 1971-04-15 | ||
GB1349308A (en) * | 1971-08-23 | 1974-04-03 | Pennwalt Corp | Fluorinated elastomers |
-
1989
- 1989-09-20 GB GB898921288A patent/GB8921288D0/en active Pending
-
1990
- 1990-09-20 GB GB9020561A patent/GB2236070B/en not_active Expired - Fee Related
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1228438A (en) * | 1964-11-23 | 1971-04-15 | ||
GB1349308A (en) * | 1971-08-23 | 1974-04-03 | Pennwalt Corp | Fluorinated elastomers |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2699844A1 (en) * | 1992-12-30 | 1994-07-01 | Snecma | Method and device for laser beam machining |
EP0618036A1 (en) * | 1992-12-30 | 1994-10-05 | Societe Nationale D'etude Et De Construction De Moteurs D'aviation "Snecma" | Process and apparatus for machining with laser beam |
US6407362B1 (en) * | 1998-07-22 | 2002-06-18 | Hydraulik-Ring Gmbh | Protective device for producing very small bores in tubular components, and method for producing bores |
WO2016055345A1 (en) * | 2014-10-09 | 2016-04-14 | Siemens Aktiengesellschaft | Method for producing through-holes in a wall of a component, by means of laser radiation |
Also Published As
Publication number | Publication date |
---|---|
GB9020561D0 (en) | 1990-10-31 |
GB2236070B (en) | 1993-06-09 |
GB8921288D0 (en) | 1989-11-08 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20070920 |