Patent Application
20160059374
This invention relates to devices for lapping a surface, and more particularly, to a lapping tool having removable lapping inserts for lapping sealing surfaces of fittings used in a gas turbine.
Fuel supply lines are attached to fuel system components of a gas turbine by fittings. The fittings each include a sealing arrangement that utilizes metal to metal contact in order to inhibit the leakage of fuel from the fitting. Referring to
In use, the cone portion 10 is received by a receptacle portion of the fitting. The receptacle portion includes a cavity having a tapered receptacle sealing surface which corresponds to the taper of the first 14 and second 16 sealing surfaces. When a fuel supply line is attached to a fuel system component, the first 14 and second 16 sealing surfaces come in contact with the receptacle sealing surface and form a seal. It is noted that the clearance surface 12 is located beneath the plane of first 14 and second 16 sealing surfaces. Thus, the clearance surface 12 does not contact the receptacle sealing surface and does not provide any sealing functionality.
Sections of the first 14 and/or second 16 sealing surfaces and/or clearance surface 12 may become damaged as a result of accidental contact with another component or equipment. For example, this may occur if the fuel line is accidentally dropped by an operator during assembly operations. In particular,
Referring to
A damaged portion of a fitting, such as cone portion 10, is replaced by cutting the cone portion 10 from the fuel line and welding a new cone portion 10 in its place. The weld then undergoes an x-ray inspection procedure to verify that welding requirements are met. However, welding requires a qualified welder and a hot work permit. In addition, performing an x-ray inspection requires a certified technician and the clearance of personnel from the work area in order to prevent exposure to x-rays. Further, there is a long wait time in obtaining replacement fittings. As such, the current process for replacing a damaged fitting is expensive and time consuming.
A lapping tool for lapping sealing surfaces of a fitting used in a gas turbine is disclosed. The tool includes a shaft having first and second ends and a longitudinal axis. A removable handle is attached to the first end and is oriented in a direction transverse to the axis. The tool also includes a removable lapping insert having an outwardly extending attachment portion that is attached to the second end of the shaft. The lapping insert includes a lapping surface which corresponds to the shape of a sealing surface of the fitting. In one embodiment, the lapping insert includes a cavity for receiving a cone portion of a fitting. Alternatively, the lapping insert includes a projection for insertion into a receptacle portion of a fitting.
While the specification concludes with claims particularly pointing out and distinctly claiming the present invention, it is believed that the present invention will be better understood from the following description in conjunction with the accompanying Drawing Figures, in which like reference numerals identify like elements, and wherein:
In the following detailed description of the preferred embodiment, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration, and not by way of limitation, a specific preferred embodiment in which the invention may be practiced. It is to be understood that other embodiments may be utilized and that changes may be made without departing from the spirit and scope of the present invention.
Referring to
A first end 40 of the shaft 28 includes a first hole 42 oriented along a longitudinal axis 44 of the shaft 28. The first insert 32 includes an outwardly extending attachment portion 46 which is received by the first hole 42. A fastener 48 extends through the shaft 28 in a direction transverse to the axis 44 and abuts against the attachment portion 46 to removably attach the first insert 32 to the shaft 28. This enables removal of the first insert 32 and replacement with a first insert 32 having a cavity 36 that has a different size, shape or taper angle or combinations thereof.
The handle 30 extends through a through hole 50 located on a second end 41 of the shaft and is oriented in a direction transverse to the axis 44. A fastener 52 extends through the shaft 28 and abuts against the handle 30 to removably attach the handle 30 to the shaft 28. The handle 30 may be grasped by an operator to enable clockwise and counterclockwise rotation of the shaft 28 and thus the housing 34 about the axis 44. In addition, the handle 30 may be replaced by a longer handle in order to provide additional leverage for rotating the shaft 28 or by a shorter handle due to space limitations. Further, the shaft 28 may be knurled in order to assist in holding and stabilizing the shaft 28 while the shaft 28 is being rotated.
Referring to
The tool 26 is used in conjunction with a paste impregnated with abrasive particles, i.e. a lapping compound, to remove raised material from a surface in order to provide a smooth surface finish. The lapping compound is applied between a surface to be lapped and the internal cavity wall 35 of the first insert 32 or the outer wall 64 of the second insert 54. The tool 26 is then rotated by hand using the handle 30 in partial clockwise and counterclockwise directions in an oscillating motion to remove raised material on the surface in order to provide a relatively smooth surface. The surface may also be lapped in a plurality of sequential stages, at first using relatively course abrasive particles and subsequently using progressively finer abrasive particles until a desired smooth surface finish is achieved.
In one embodiment, the tool 26 is used to lap a cone portion of a fitting used in a gas turbine such as cone portion 10 previously described in relation to
Referring to
Referring to
The bluing tool 66 is used in conjunction with a paste known as engineer's blue to determine whether a high spot exists on a surface. In use, the paste is applied to the bluing tool 66. The lead end 70 of the bluing tool 66 is then inserted into the cavity of the receptacle portion of a fitting. Any high spots on the receptacle sealing surface 22 contacts the bluing tool 66. This causes a portion of the engineer's blue that is contacted by a high spot to transfer to the high spot, thus indicated the location of the high spot. A lapping procedure may then be used to reduce the high spot. In one embodiment, the bluing tool 66 is fabricated from tool steel in order to avoid galling or other damage to the receptacle sealing surface 22.
Thus, the first 32 and second 54 inserts and the bluing tool 66 may each be removably attached to the shaft 28. This enables lapping of the first 14 and second 16 sealing surfaces of cone portion 10 and the receptacle sealing surface 22 of a receptacle portion, in addition to checking for high spots in a sealing surface, through the use of a single tool. Further, the tool 26 enables repair of a fitting of a gas turbine thereby eliminating the need to remove the fitting and welding a new fitting in its place, thus avoiding associated costs and time delays.
While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.
