Patent Application
20190321935
The present disclosure relates generally to methods of finishing internal portions of additively manufactured components and, more particularly, to methods and apparatus in which a mandrel is used to smooth walls of passageways extending within additively manufactured components.
Fabrication processes such as additive manufacturing enable fabrication of article geometries that are difficult or otherwise impossible to make by other fabrication techniques. For example, components in gas turbine engines may include internal passages for conveying coolants or lubricants. Additive manufacturing and other advances permit such passages to be formed having complex geometries within thin wall structures and having high-aspect ratios. However, due to the additive manufacturing process, and even with other fabrication processes, the surfaces of these passages can be rough following the fabrication process. If left in the final component, this surface roughness has the potential to interfere with fluid flow through the passageways.
Abrasive machining is a technique used to smooth surface roughness on the inner surfaces of conduits or passageways in additively manufactured components. The technique involves forcing an abrasive media through the conduits or passageways to abrade or wear away the surface roughness on the inner surfaces. In certain instances, however, a steep velocity gradient can develop within the conduit or passageway, resulting in the abrasive material flowing freely within a center region of the conduit or passageway and flowing very slowly or not at all near the surfaces requiring smoothing. The phenomena may be characterized, in various situations, as a Poiseuille-type flow through a pipe, where the velocity of the fluid is greatest near the center of the pipe and approaches zero near the boundary of the pipe.
A method for smoothing surface roughness within a passageway is disclosed. In various embodiments, the method comprises flowing an abrasive media through the passageway and positioning a first mandrel within the passageway, the first mandrel being sized to create a gap between an outer surface of the first mandrel and an inner surface of the passageway, the abrasive media being caused to flow through the gap, abrading the inner surface of the passageway.
In various embodiments, the first mandrel is positioned at different locations within the passageway during a first smoothing operation. In various embodiments, positioning the first mandrel at different locations occurs through a passive process by action of friction between the outer surface of the first mandrel and the inner surface of the passageway. In various embodiments, the abrasive media is caused to flow in a forward direction followed by a reverse direction. In various embodiments, the first smoothing operation if followed by a second smoothing operation using a second mandrel, the second mandrel being sized larger than the first mandrel.
In various embodiments, the first mandrel is connected to a cable configured to position the first mandrel at different locations. In various embodiments, the cable is connected to a cable reel configured to pay out the cable in a downstream direction. In various embodiments, the cable reel is configured to withdraw the cable in an upstream direction. In various embodiments, the passageway includes a circular cross section and the first mandrel is a first sphere. In various embodiments, a second sphere is connected to the cable adjacent the first sphere.
In various embodiments, a first smoothing operation comprises traversing the first mandrel from an inlet of the passageway to an exit of the passageway followed by traversing the first mandrel from the exit of the passageway to the inlet of the passageway. In various embodiments, traversing the first mandrel from the exit of the passageway to the inlet of the passageway is caused to occur by withdrawing a cable connected to the first mandrel. In various embodiments, traversing the first mandrel from the exit of the passageway to the inlet of the passageway is caused to occur by reversing a flow direction of the abrasive media. In various embodiments, the first mandrel includes a non-spherical shape.
An apparatus for smoothing surface roughness within a passageway is disclosed. In various embodiments, the apparatus includes an abrasive flow machine configured to pump abrasive media through a component having the passageway and a mandrel configured for variable positioning along a length within the passageway, the mandrel being sized to create a gap between an outer surface of the mandrel and an inner surface of the passageway.
In various embodiments, the mandrel is sized to enable friction between the outer surface of the mandrel and the inner surface of the passageway to control the variable positioning. In various embodiments, that apparatus further includes a cable reel and a cable connected to the mandrel, the cable reel being configured to control the variable positioning. In various embodiments, the passageway includes a circular cross section and the mandrel is a sphere.
A method for smoothing surface roughness within a passageway is disclosed. In various embodiments, the method comprises the steps of, positioning a mandrel within the passageway, the mandrel being sized to create a gap between an outer surface of the mandrel and an inner surface of the passageway; flowing an abrasive media through the passageway in a first direction; and moving the mandrel in the first direction, the abrasive media being caused to flow through the gap, abrading the inner surface of the passageway upstream of the mandrel. In various embodiments, the passageway and the mandrel have a non-circular cross section and the positioning of the mandrel is controlled by a rod connected to a downstream portion of the mandrel.
The subject matter of the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of the specification. A more complete understanding of the present disclosure, however, may best be obtained by referring to the following detailed description and claims in connection with the following drawings. While the drawings illustrate various embodiments employing the principles described herein, the drawings do not limit the scope of the claims.
The following detailed description of various embodiments herein makes reference to the accompanying drawings, which show various embodiments by way of illustration. While these various embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, it should be understood that other embodiments may be realized and that changes may be made without departing from the scope of the disclosure. Thus, the detailed description herein is presented for purposes of illustration only and not of limitation. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, connected, or the like may include permanent, removable, temporary, partial, full or any other possible attachment option. Additionally, any reference to without contact (or similar phrases) may also include reduced contact or minimal contact. It should also be understood that unless specifically stated otherwise, references to “a,” “an” or “the” may include one or more than one and that reference to an item in the singular may also include the item in the plural. Further, all ranges may include upper and lower values and all ranges and ratio limits disclosed herein may be combined.
Referring now to the drawings,
The gas turbine engine 20 generally includes a low speed spool 30 and a high speed spool 32 mounted for rotation about an engine central longitudinal axis A relative to an engine static structure 36 via several bearing systems 38. It should be understood that various bearing systems at various locations may alternatively or additionally be provided and the location of the several bearing systems 38 may be varied as appropriate to the application. The low speed spool 30 generally includes an inner shaft 40 that interconnects a fan 42, a low pressure compressor 44 and a low pressure turbine 46. The inner shaft 40 is connected to the fan 42 through a speed change mechanism, which in this gas turbine engine 20 is illustrated as a fan drive gear system 48 configured to drive the fan 42 at a lower speed than the low speed spool 30. The high speed spool 32 includes an outer shaft 50 that interconnects a high pressure compressor 52 and a high pressure turbine 54. A combustor 56 is arranged in the gas turbine engine 20 between the high pressure compressor 52 and the high pressure turbine 54. A mid-turbine frame 57 of the engine static structure 36 is arranged generally between the high pressure turbine 54 and the low pressure turbine 46 and may include airfoils 59 in the core flow path C for guiding the flow into the low pressure turbine 46. The mid-turbine frame 57 further supports the several bearing systems 38 in the turbine section 28. The inner shaft 40 and the outer shaft 50 are concentric and rotate via the several bearing systems 38 about the engine central longitudinal axis A, which is collinear with their longitudinal axes.
The air in the core flow path is compressed by the low pressure compressor 44 and then the high pressure compressor 52, mixed and burned with fuel in the combustor 56, and then expanded over the high pressure turbine 54 and low pressure turbine 46. The low pressure turbine 46 and the high pressure turbine 54 rotationally drive the respective low speed spool 30 and the high speed spool 32 in response to the expansion. It will be appreciated that each of the positions of the fan section 22, the compressor section 24, the combustor section 26, the turbine section 28, and the fan drive gear system 48 may be varied. For example, the fan drive gear system 48 may be located aft of the combustor section 26 or even aft of the turbine section 28, and the fan section 22 may be positioned forward or aft of the location of the fan drive gear system 48.
Various components of the gas turbine engine 20 include conduits or passageways extending through the component or a portion thereof. For example, components in the gas turbine engine 20 may include internal passages for conveying a coolant. Such components include, for example, the blades and the stators that comprise the compressor and turbine sections described above. Such components may also comprise passageways for conveying bleed air from the compressor to other areas of the gas turbine engine 20 benefitting from a source of high-pressure cooling fluid. Other components comprising conduits or passageways include the lubrication system, where lubricants are delivered from a pump to bearings and the like. Many of these various components are constructed using additive manufacturing techniques and include conduits or passageways having curved portions with rough internal surfaces following their manufacture.
Referring now to
Referring now to
A component 300, such as the component 200 with the passageway 202 described above with reference to
As mentioned above, increasingly higher aspect ratios of the passageway 302 may cause increasingly higher pressure drop of the flow F of abrasive media across the length of the passageway 302. In this regard, the abrasive media of the method may have a low-viscosity formulation that enables the pump 352 to move the abrasive media through the passageway 302. For example, the abrasive media may include a carrier liquid material and solid particulate (abrasive material). In various embodiments, the carrier liquid is, without limitation, one or more of water, a solvent and a liquid hydrocarbon, or mixtures thereof. In various embodiments, the solid particulate may be, but is not limited to, one or more of silicon carbide and aluminum oxide, or mixtures thereof.
As also described above, in various embodiments, a steep velocity gradient can develop within the passageway 302, resulting in the abrasive material flowing freely within the interior or center of the passageway 302 and flowing very slowly or not at all near the inner surfaces requiring smoothing—e.g., near an inner surface 308 of the passageway 302. Accordingly, in various embodiments, a mandrel—e.g., a sphere 370—is placed within the fluid circuit, comprising the tube network 354 and the passageway 302 of the component 300, to tailor the flow characteristics of the abrasive media to more effectively abrade the inner surface 308. As described further below, as the sphere 370 is forced through the passageway 302 by the abrasive media, a leakage flow of abrasive media between an outer surface 372 of the sphere 370 and the inner surface 308 of the passageway 302 is established, which focuses the abrading effect of the abrasive media away from the interior or center of the passageway 302 and toward the inner surface 308 of the passageway 302.
Referring to
Referring to
Once the sphere 370 approaches or exits the second end, the abrasive flow machine 350 may be turned off and the component 300 removed from the machine. Alternatively, in various embodiments, the pump 352 may be reversed, forcing the sphere 370 back to the first end 304 for additional smoothing in the opposite direction as that just described. In various embodiments, the process may be repeated using progressively larger spheres until a desired smoothing is obtained. In various embodiments, multiple spheres, having the same dimensions as the sphere 370 above described, or even dissimilar dimensions among the multiple spheres, may be forced through the passageway 302 simultaneously, as a progression of spheres, providing a further enhancement of the smoothing effect of the abrasive media as it and the spheres are forced through the passageway 302 by action of the abrasive flow machine 350.
Referring now to
A component 400, such as the component 200 with the passageway 202 described above with reference to
Starting with
Referring to
Once the sphere 470 approaches or exits the second end, the abrasive flow machine 450 may be turned off and the component 400 removed from the machine. Alternatively, in various embodiments, the cable reel 469 reverses direction and, rather than paying out the cable 464 to allow the sphere 470 to flow downstream against the flow F of abrasive media 476, the cable 464 is used to pull the sphere upstream against the flow F of the abrasive media 476. The process may be repeated as required until a desired smoothness is achieved. In various embodiments, the process may be repeated using progressively larger spheres until a desired smoothing is obtained. In various embodiments, multiple spheres, having the same dimensions as the sphere 470 above described, or even dissimilar dimensions among the multiple spheres, may be forced through the passageway 402 simultaneously, as a progression of spheres, providing a further enhancement of the smoothing effect of the abrasive media as it and the spheres are forced through the passageway 402 by action of the abrasive flow machine 450. In various embodiments, the multiple spheres may be arranged similar to pearls on a neckless, with a first sphere secured to the cable 464 and the remaining spheres threaded on to the cable, with the cable running through holes drilled through the spheres.
Referring now to
Referring now to
In various embodiments, the mandrel 500 is sized with respect to the passageway 520 such that a gap 532 extends between an outer surface 534 of the mandrel 500 and an inner surface 538 of the passageway 520. In various embodiments, the gap 532 extends about the mandrel 500 and provides a narrow passage for the flow of abrasive media 530 to be forced along the inner surface 538 of the passageway 520, between the inner surface 538 and the outer surface 534 of the mandrel 500. Forcing the abrasive media 530 through the gap 532 results in the abrading effect of the abrasive media 530 to focus on the inner surface 538 of the passageway 520 rather than merely flowing through the interior or center of the passageway 520 where little to no abrasion occurs. In various embodiments, the gap 532 may have a non-dimensional dimension of one (1) to ten (10) one-hundredths the height or width of the mandrel 500. In various embodiments, the gap 532 may have a size equal from about five-hundred (500) microns (≈1.96 E-02 inches) to about five-thousand (5000) microns (≈1.96 E-01 inches).
In various embodiments, the passageway 520 is substantially straight along an axial direction—e.g., along the direction of flow of the abrasive media. In various embodiments, the passageway is curved, similar to the curved passageways described above. For curved passageways, a length 540 of the mandrel 500 is sized sufficiently to permit the mandrel 500 to traverse the curved passageway. While the mandrel 500 has been described having a specific geometry, the disclosure contemplates mandrel of other shapes and cross sections, with various numbers of protrusions or depressions extending from or within various surfaces of the mandrel, so the specific shape described above for the mandrel 500 should not be considered limiting.
Finally, it should be understood that any of the above described concepts can be used alone or in combination with any or all of the other above described concepts. Although various embodiments have been disclosed and described, one of ordinary skill in this art would recognize that certain modifications would come within the scope of this disclosure. Accordingly, the description is not intended to be exhaustive or to limit the principles described or illustrated herein to any precise form. Many modifications and variations are possible in light of the above teaching.
Benefits, other advantages, and solutions to problems have been described herein with regard to specific embodiments. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical system. However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the disclosure. The scope of the disclosure is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” Moreover, where a phrase similar to “at least one of A, B, or C” is used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B and C may be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C. Different cross-hatching is used throughout the figures to denote different parts but not necessarily to denote the same or different materials.
Systems, methods and apparatus are provided herein. In the detailed description herein, references to “one embodiment”, “an embodiment”, “various embodiments”, etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments.
Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. 112(f) unless the element is expressly recited using the phrase “means for.” As used herein, the terms “comprises”, “comprising”, or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
