Fixture system and method for securing an airfoil during material removal operations

A method of removing material from an airfoil includes engaging a root of the airfoil within a root-securing fixture, engaging a tip of the airfoil within a tip-securing fixture, and removing material from the airfoil. The method further includes disengaging the tip of the airfoil from the tip-securing fixture to allow movement of the tip from a clamped state position to a free-state position. The method further includes reengaging the tip of the airfoil within the tip-securing fixture in the free-state position, and removing additional material from the airfoil.

BACKGROUND

This disclosure relates generally to turbomachinery, and in particular to manufacturing and machining of airfoils used in the turbomachinery.

Turbomachinery can provide efficient, reliable power for a wide range of applications, including aviation and industrial power generation. Aviation applications often include turbojet, turbofan, turboprop, and turboshaft engines. Gas turbine engines are rotary-type combustion turbine engines built around a power core made up of a compressor, combustor, and turbine arranged in flow series with an upstream inlet and downstream exhaust. The compressor compresses air from the inlet, which is mixed with fuel in the combustor and ignited to generate hot combustion gas. The turbine extracts energy from the expanding combustion gas, and drives the compressor via a common shaft. Energy is delivered in the form of rotational energy in the shaft, reactive thrust from the exhaust, or both.

Turbofan engines are commonly divided into high and low bypass configurations. High bypass turbofans generate thrust primarily from the fan, which drives airflow through a bypass duct oriented around the engine core. This design is common on commercial aircraft and military transports, where noise and fuel efficiency are primary concerns. Low bypass turbofans generate proportionally more thrust from the exhaust flow, providing greater specific thrust for use on high-performance aircraft, including supersonic jet fighters. Unducted (open rotor) turbofans and ducted propeller engines are also known, and are often utilized in a variety of counter-rotating and aft-mounted configurations.

Turbofan and turbojet engines are often subdivided into a number of stages, which are formed of alternating rows of rotor blade and stator vane airfoils. The airfoils are shaped to turn, accelerate, and compress the working fluid flow, or to generate lift for conversion to rotational energy in, e.g., a turbine. Accordingly, efficient engine performance depends upon precise control of the working fluid flow, including flow across fan, combustor, and turbine airfoils. Such precise control requires highly accurate manufacturing techniques to form the airfoil surfaces within specified design tolerances. To this end, material is typically removed from initially-forged or cast airfoils to meet design tolerances using sophisticated tooling systems, such as computer numerical control (CNC) machining systems. Often, the airfoil is secured within the tooling system using fixtures that prevent movement of the blade during material removal. However, in some cases, the airfoil can warp or otherwise deform upon release from the fixtures, possibly resulting in a finished airfoil that does not meet design specifications.

SUMMARY

In one example, a method of removing material from an airfoil comprises engaging a root of the airfoil within a root-securing fixture, engaging a tip of the airfoil within a tip-securing fixture, and removing material from the airfoil. The method further includes disengaging the tip of the airfoil from the tip-securing fixture to allow movement of the tip from a clamped-state position to a free-state position, reengaging the tip of the airfoil within the tip-securing fixture in the free-state position, and removing additional material from the airfoil.

In another example, a fixture system for securing an airfoil during material removal operations includes a root-securing fixture configured to engage a root of the airfoil, a tip-securing fixture configured to be selectively engageable and disengageable from a tip of the airfoil, and a control system. The control system is configured to cause the tip-securing fixture to engage the tip during initial removal of material from the airfoil and to disengage the tip after the initial removal of material to allow movement of the tip from a clamped-state position to a free-state position. The control system is further configured to cause the tip-securing fixture to reengage the tip in the free-state position during additional removal of material from the airfoil.

DETAILED DESCRIPTION

According to techniques of this disclosure, a fixture system can disengage a tip of an airfoil after initial material removal (e.g., during machining or other finishing operations), thereby helping to compensate for the release of internal stresses (e.g., forging stresses) resulting from the removal of the material. By disengaging the tip of the airfoil after the initial material removal (e.g., eighty to ninety percent of the material to be removed during the finishing operations), the fixture system can allow movement of the tip of the airfoil from a clamped-state position to a new, free-state position. Thereafter, the fixture system can reengage the tip in the free-state position for additional material removal (e.g., a remainder of the material to be removed during the finishing operations). That is, rather than reengage the airfoil by clamping the airfoil against an immobile hard-stop of the fixture that was used for initial material removal, a fixture system implementing techniques described herein can reengage the blade in the new, free-state position without causing significant deformation from the free-state position. In this way, a fixture system implementing techniques of this disclosure can help to minimize warping or other deformation of the airfoil due to internal stress relief resulting from the material removal process. Moreover, the fixture system can be automated to disengage and reengage the airfoil, thereby decreasing the amount of operator intervention (and the associated costs) required during the material removal process.

FIG. 1is a perspective view of fixture system10that can be used for securing airfoil12during material removal operations. As illustrated inFIG. 1, fixture system10can include root-securing fixture14and tip-securing fixture16. Airfoil12can include root18and tip20. Airfoil12can be, e.g., a rotor blade, such as a fan blade, compressor blade, turbine blade, or other airfoil formed of aluminum, titanium, or other lightweight material having high tensile strength properties. Root-securing fixture14can be configured to secure root18during the material removal process, such as by fixedly clamping or otherwise securing root18. Tip-securing fixture16can be configured to selectively engage and disengage tip20during the material removal process, as is further described below.

Typically, airfoils used in turbomachinery are cast or forged to an initial form that approximates a final shape of the airfoil as defined by design specifications. Thereafter, the airfoil is subjected to a material removal process that removes excess material to shape the airfoil to meet the design specifications. For instance, as illustrated inFIG. 1, airfoil12can be secured (e.g., by root-securing fixture14and tip-securing fixture16) within a milling machine, such as a computer numerical control (CNC) system that includes drills, lathes, cutters, or other tooling to remove excess material from the airfoil. As in the example ofFIG. 1, root-securing fixture14and tip-securing fixture16can be connected to rotating headstocks22and24, respectively. Each of rotating headstocks22and24can rotate (e.g., as controlled by a control system included in or coupled to the milling machine) about an axis of rotation that, in the example ofFIG. 1, extends radially along a span of airfoil12. In addition, each of headstocks22and24can be movable to provide six degrees of freedom during material removal by, e.g., tooling26. While the material removal process is described in the example ofFIG. 1with respect to a milling machine, it should be appreciated that techniques of this disclosure are not so limited, but may be applicable to other material removal processes, such as electrical discharge machining (EDM) operations.

The initial casting or forging process can introduce internal stresses within airfoil12. Removal of material from the cast/forged state can relieve such internal stresses, thereby causing warping or other deformation of airfoil12upon release from fixture system10. Such deformation can be particularly pronounced at thinner parts of airfoil12, such as at or near tip20. Accordingly, as is further described below, tip-securing fixture16can be configured to disengage tip20after initial material removal from airfoil12to enable movement of tip20from a clamped-state position (i.e., a position of tip20prior to the initial material removal) to a new, free-state position (i.e., a position of tip20after initial material removal). As one example, the initial material removal can include eighty to ninety percent of the material to be removed from airfoil12during the material removal process, though other ranges are possible. Thereafter, tip-securing fixture16can reengage tip20in the free-state position for additional material removal, such as removal of a remainder of material to conform a shape of airfoil12to design specifications. As such, fixture system10can decrease an amount of deformation of airfoil12(e.g., at tip20) due to the release of stresses internal to airfoil12.

FIG. 2is an enlarged perspective view of tip-securing fixture16ofFIG. 1. As illustrated inFIG. 2, airfoil12can include leading edge28and trailing edge30. Tip20of airfoil12can include radially outer edge32. Each of leading edge tab34, trailing edge tab36, and center tab38extend from radially outer edge32and can be integrally formed from tip20during prior machining operations to facilitate interaction of tip-securing fixture16with airfoil12. In other examples, one or more of tabs34,36, and38can be added to tip20, such as by welding or other operations. Leading edge tab34is disposed proximate leading edge28of airfoil12. Trailing edge tab36is disposed proximate trailing edge30of airfoil12. Center tab38is disposed along radially outer edge32between leading edge tab34and trailing edge tab36, such as at or near a central radial axis of airfoil12.

As further illustrated inFIG. 2, tip-securing fixture16can include leading edge clamping assembly40, trailing edge clamping assembly42, and centering pin44. Leading edge clamping assembly40includes leading edge positioning member46and leading edge clamping member48. Trailing edge clamping assembly42includes trailing edge positioning member50and trailing edge clamping member52.

Leading edge clamping assembly40, trailing edge clamping assembly42, and centering pin44are configured to be selectively engageable and disengageable from leading edge tab34, trailing edge tab36, and center tab38, respectively. For instance, as is further described below, positioning member46is movable to engage and disengage a forward side of leading edge tab34. Leading edge clamping member48is movable to engage and disengage an aft side of leading edge tab34. Trailing edge positioning member50is movable to engage and disengage an aft side of trailing edge tab36. Trailing edge clamping member is movable to engage and disengage a forward side of trailing edge tab36. Centering pin44is movable to engage and disengage a bore (not illustrated) that extends radially inward from a radially outer side of center tab38.

In operation, and as further described below, centering pin44engages center tab38, leading edge clamping assembly40engages leading edge tab34, and trailing edge clamping assembly42engages trailing edge tab36during initial material removal from airfoil12. In response to a threshold amount of material removal (e.g., eighty to ninety percent of the material to be removed during the material removal process), centering pin44disengages center tab38, leading edge clamping assembly40disengages leading edge tab34, and trailing edge clamping assembly42disengages trailing edge tab36to allow movement of tip20from a clamped-state position to a new, free-state position. Thereafter, leading edge clamping assembly40and trailing edge clamping assembly42reengage leading edge tab34and trailing edge tab36, respectively, during additional removal of material from airfoil12. In some examples, centering pin44remains in a disengaged position (e.g., retracted from the bore of center tab38) during the additional removal of material.

FIG. 3is a flow diagram illustrating example operations of fixture system10to selectively engage and disengage tip20of airfoil12. Further details of each of the example operations ofFIG. 3are described below with respect to the following figures.

Tip-securing fixture16can engage centering pin44with center tab38(step54). Tip-securing fixture16can engage leading edge positioning member46with a forward side of leading edge tab34, and can engage trailing edge positioning member50with an aft side of trailing edge tab36(step56). Tip-securing fixture16can engage leading edge clamping member48with an aft side of leading edge tab34, and can engage trailing edge clamping member52with a forward side of trailing edge tab36(step58). Material can be removed from airfoil12(step60). Tip-securing fixture16can disengage centering pin44from center tab38, leading edge positioning member46from leading edge tab34, leading edge clamping member48from leading edge tab34, trailing edge positioning member50from trailing edge tab36, and trailing edge clamping member52from trailing edge tab36to allow movement of tip20from a clamped-state position to a free-state position (step62).

Tip-securing fixture16can reengage leading edge positioning member46with the forward side of leading edge tab34in the free-state position, and can reengage trailing edge positioning member50with the aft side of trailing edge tab36in the free-state position (step64). Tip-securing fixture16can reengage leading edge clamping member48with the aft side of leading edge tab34in the free-state position, and can reengage trailing edge clamping member52with the forward side of trailing edge tab36in the free-state position (step66). Additional material can be removed from airfoil12(step68).

FIG. 4is a schematic block diagram illustrating control system70that can be utilized for control of fixture system10. Control system70can be any combination of software and/or hardware configured to control operation of fixture system10to selectively engage and disengage tip-securing fixture16with tip20of airfoil12. Control system70can include, in some examples, one or more processors and computer-readable memory configured to store instructions that, when executed by the one or more processors, cause fixture system10to operate in accordance with techniques described herein.

Examples of one or more processors include any one or more of a microprocessor, a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other equivalent discrete or integrated logic circuitry. Computer-readable memory can include volatile memory, such as random access memories (RAM), dynamic random access memories (DRAM), static random access memories (SRAM), and other forms of volatile memories. In some examples, computer-readable memory can include non-volatile memory, such as magnetic hard discs, optical discs, floppy discs, flash memories, or forms of electrically programmable memories (EPROM) or electrically erasable and programmable memories (EEPROM). In certain examples, computer-readable memory can include a non-transitory medium. The term “non-transitory” can indicate that the storage medium is not embodied in a carrier wave or a propagated signal.

Control system70can, in some examples, be considered a controller device configured to control operation of fixture system10to secure airfoil12during a material removal process. In certain examples, control system70can be integrated with a material removal machine, such as a CNC milling machine. In other examples, control system70can be separate from, but communicatively coupled to, one or more of the material removal machine and fixture system10.

As illustrated inFIG. 4, control system70can be coupled with material removal tooling26, root-securing fixture14, and leading edge clamping assembly40, trailing edge clamping assembly42, and centering pin44of tip-securing fixture16. Such couplings can include any one or more of electrical couplings and communicative couplings (e.g., via a computer network). In general, control system70can include any combination of hardware and/or software configured to control operation of fixture system10, such as to cause tip-securing fixture16to engage tip20during initial material removal, disengage tip20to allow movement of tip20from a clamped-state position to a free-state position, and to reengage tip20in the free-state position for additional material removal.

FIGS. 5A-5Dillustrate example states of tip-securing fixture16to engage, release, and reengage tip20of airfoil12. Specifically,FIG. 5Aillustrates an example of tip-securing fixture16engaged with tip20, such as during initial material removal from airfoil12.FIG. 5Billustrates an example of tip-securing fixture16disengaged from tip20to allow movement of tip20from a clamped-state position to a free-state position.FIG. 5Cillustrates an example of tip-securing fixture16with leading edge positioning member46reengaged with leading edge tab34and trailing edge positioning member50reengaged with trailing edge tab36in the free-state position of tip20.FIG. 5Dillustrates an example of tip-securing fixture16with leading edge positioning member46and leading edge clamping member48engaged with leading edge tab34, and trailing edge positioning member50and trailing edge clamping member52engaged with trailing edge tab36in the free-state position of tip20.

FIG. 5Ais a perspective view of tip-securing fixture16engaged with tip20of airfoil12. As illustrated inFIG. 5A, leading edge positioning member46is engaged with forward side72of leading edge tab34. Leading edge clamping member48is engaged with aft side74of leading edge tab34. In operation, leading edge clamping member48applies force (e.g., ninety bars, one hundred bars, or other amounts of force) against leading edge tab34in a direction that is generally opposite leading edge positioning member46, which may be locked into a stationary position upon engagement with forward side72, as is further described below. In this way, leading edge clamping member48and leading edge positioning member46together act to apply a clamping force to leading edge tab34to secure leading edge tab34within tip-securing fixture16.

As further illustrated inFIG. 5A, centering pin44is engaged within a bore of center tab38to engage centering pin44with center tab38. Trailing edge positioning member50is engaged with aft side50of trailing edge tab36. Trailing edge clamping member52is engaged with forward side78of trailing edge tab36. In operation, trailing edge clamping member52applies force, such as ninety bars (approximately one-thousand three-hundred and five pounds per square inch), one hundred bars (approximately one-thousand four-hundred and fifty pounds per square inch), or other amounts of force against trailing edge tab36in a direction that is generally opposite trailing edge positioning member50, which may be locked into a stationary position upon engagement with aft side76, as is further described below. As such, trailing edge clamping member52and trailing edge positioning member50together act to apply a clamping force to trailing edge tab36to secure trailing edge tab36within tip-securing fixture16.

FIG. 5Bis a perspective view of tip-securing fixture16disengaged from tip20of airfoil12. As illustrated inFIG. 5B, leading edge positioning member46is disengaged from forward face72of leading edge tab34. Leading edge clamping member48is disengaged from aft face74of leading edge tab34. Centering pin44is disengaged from center tab38. Trailing edge positioning member50is disengaged from aft face76of trailing edge tab36. Trailing edge clamping member52is disengaged from forward face78of trailing edge tab36.

As illustrated, each of leading edge positioning member46, leading edge clamping member48, trailing edge positioning member50, trailing edge clamping member52, and centering pin44are movable to selectively engage and disengage tabs34,36, and38. Each of leading edge positioning member46, leading edge clamping member48, trailing edge positioning member50, trailing edge clamping member52, and centering pin44can be pneumatically, hydraulically, or electrically actuated to induce such movement. As one example, tip-securing fixture16can include one or more of a pneumatic actuator, a hydraulic actuator, and an electrically-driven actuator (e.g., an electric motor) which can be driven by controller70(illustrated inFIG. 4) to cause movement of leading edge positioning member46, leading edge clamping member48, trailing edge positioning member50, trailing edge clamping member52, and centering pin44. As another example, tip-securing fixture16can be connected to any one or more of a pneumatic, hydraulic, and electrical actuator, e.g., via electrical connections or supply lines.

Leading edge positioning member46is movable to extend and retract in the illustrated direction A. In operation, leading edge positioning member46retracts away from forward face72along direction A to disengage forward face72. Leading edge clamping member48is movable to extend and retract in the illustrated direction B. In addition, leading edge clamping member48is rotatable in direction C. In operation, leading edge clamping member48extends away from aft face74along direction B to disengage aft face74. Thereafter, leading edge clamping member48rotates in direction C to misalign with leading edge tab34.

Centering pin44is movable to extend and retract in the illustrated direction D. In operation, centering pin44retracts from the bore in center tab38to disengage center tab38. Trailing edge clamping member52is movable to extend and retract in direction E. In addition, trailing edge clamping member52is rotatable in direction F. In operation, trailing edge clamping member52extends away from forward face78along direction E to disengage forward face78. Thereafter, trailing edge clamping member52rotates in direction F to misalign with trailing edge tab36.

As illustrated inFIG. 5B, trailing edge clamping assembly42further includes actuator80, which connects to trailing edge positioning member50. Trailing edge positioning member50is connected to trailing edge clamping assembly via pivot82. In operation, actuator80(e.g., a pneumatic actuator, a hydraulic actuator, an electrically driven actuator, or other type of actuator) is movable to extend and retract in direction G. Movement of actuator80along direction G causes rotation of trailing edge positioning member50in direction H via pivot82. In operation, actuator80retracts in direction G to cause rotation of trailing edge positioning member50in direction H away from aft face76of trailing edge tab36.

FIG. 5Cis a perspective view of tip-securing fixture16illustrating leading edge positioning member46reengaged with forward face72of leading edge tab34, and trailing edge positioning member50reengaged with aft face76of trailing edge tab36. As illustrated inFIG. 5C, leading edge clamping member48is disengaged from aft face74, trailing edge clamping member52is disengaged from forward face78, and centering pin44is disengaged from center tab38. In some examples, such as the example ofFIG. 5C, leading edge positioning member46and trailing edge positioning member50can move to an engaged position before either of leading edge clamping member48and trailing edge clamping member52move to engagement positions.

For instance, as in the example ofFIG. 5C, leading edge positioning member46can move along direction A into engagement with forward face72at a substantially same time as trailing edge positioning member50rotates in direction H into engagement with aft face76. As such, a force applied by leading edge positioning member46and trailing edge positioning member50can be generally opposing in a direction substantially along a chord of airfoil12, thereby minimizing any deformation due to the engagement of positioning members46and50. In some examples, each of positioning members46and50can be maintained in a stationary position (e.g., “locked” into place) in response to application of a relatively small, threshold amount of force, such as a force of less than five Newtons (approximately one pound of force), though other threshold amounts of force are possible. Such a small application of force can enable positioning members46and50to effectively locate tabs34and36, respectively, while airfoil12is in the free-state position and without causing substantial deformation of airfoil12. By maintaining positioning members46and50in the stationary position (e.g., a locked position) in response to the application of the threshold amount of force, positioning members46and50can provide a counter force for clamping by leading edge clamping member48and trailing edge clamping member52. For instance, clamping members48and52can each apply a relatively large clamping force, such as ninety to one hundred bars, although other ranges are possible. In this way, clamping members48and52can secure tip20in the free-state position without causing substantial deformation of airfoil12due to the applied clamping force.

FIG. 5Dis a perspective view of tip-securing fixture16illustrating leading edge clamping member48reengaged with aft face74of leading edge tab34and trailing edge clamping member52reengaged with forward face78of trailing edge tab36. As illustrated inFIG. 5D, centering pin44is disengaged from center tab38. In some examples, such as the example ofFIG. 5D, centering pin44can be maintained in a disengaged position during additional removal of material from airfoil12, thereby compensating for movement of tip20that could misalign centering pin44from the bore in center tab38.

In operation, leading edge clamping member48rotates in direction C to align with leading edge tab34. Thereafter, leading edge clamping member48retracts along direction B to engage aft face74and apply a clamping force (e.g., one hundred bars of force). Trailing edge clamping member52rotates in direction F to align with trailing edge tab36. Thereafter, trailing edge clamping member52retracts along direction E to engage forward face78and apply a clamping force (e.g., one hundred bars of force).

Accordingly, fixture system10implementing techniques of this disclosure can cause tip-securing fixture16to disengage tip20of airfoil12after initial removal of material to allow movement of tip20from a clamped-state position to a free-state position. Thereafter, fixture system10can cause tip-securing fixture16to reengage tip20for additional removal of material without causing significant deformation from the free-state position. As such, fixture system10can decrease a total amount of deformation of airfoil12caused by the release of internal stresses during the material removal process.

Discussion of Possible Embodiments

A method of removing material from an airfoil includes engaging a root of the airfoil within a root-securing fixture, engaging a tip of the airfoil within a tip-securing fixture, and removing material from the airfoil. The method further includes disengaging the tip of the airfoil from the tip-securing fixture to allow movement of the tip from a clamped-state position to a free-state position, reengaging the tip of the airfoil within the tip-securing fixture in the free-state position, and removing additional material from the airfoil.

The method of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations, operations, and/or additional components:

Engaging the tip of the airfoil within the tip-securing fixture can include engaging each of a plurality of tabs extending from a radially outer edge of the tip of the airfoil within the tip-securing fixture. Disengaging the tip of the airfoil from the tip-securing fixture can include disengaging each of the plurality of tabs from the tip-securing fixture.

The plurality of tabs can include a leading edge tab proximate a leading edge of the airfoil, a trailing edge tab proximate a trailing edge of the airfoil, and a center tab disposed between the leading edge tab and the trailing edge tab. The center tab can have a bore extending radially inward from a radially outer side of the center tab. The tip-securing fixture can include a leading edge clamping assembly configured to be selectively engageable and disengageable from the leading edge tab, a trailing edge clamping assembly configured to be selectively engageable and disengageable from the trailing edge tab, and a centering pin configured to be selectively inserted into and retracted from the bore of the center tab. Engaging the tip of the airfoil within the tip-securing fixture can include engaging the leading edge clamping assembly with the leading edge tab, engaging the trailing edge clamping assembly with the trailing edge tab, and inserting the centering pin into the bore of the center tab. Disengaging the tip of the airfoil from the tip-securing fixture can include disengaging the leading edge clamping assembly from the leading edge tab, disengaging the trailing edge clamping assembly from the trailing edge tab, and retracting the centering pin from the bore of the center tab.

Reengaging the tip of the airfoil within the tip-securing fixture can include engaging the leading edge clamping assembly with the leading edge tab and engaging the trailing edge clamping assembly with the trailing edge tab.

Reengaging the tip of the airfoil within the tip-securing fixture can include maintaining the centering pin in a disengaged state.

Engaging the centering pin in the bore of the centering tab can include moving the centering pin into the bore of the centering tab. Engaging the leading edge tab within the leading edge clamping assembly can include moving a leading edge positioning member of the leading edge clamping assembly into engagement with a forward side of the leading edge tab and moving a leading edge clamping member of the leading edge clamping assembly into engagement with an aft side of the leading edge tab. Engaging the trailing edge tab within the trailing edge clamping assembly can include moving a trailing edge positioning member of the trailing edge clamping assembly into engagement with an aft side of the trailing edge tab and moving a trailing edge clamping member of the trailing edge clamping assembly into engagement with a forward side of the trailing edge tab.

Both of the leading edge positioning member and the trailing edge positioning member can be moved into engagement before either of the leading edge clamping member and the trailing edge clamping member are moved into engagement.

Moving each of the leading edge clamping member and the trailing edge clamping member into engagement with the respective one of the leading edge tab and the trailing edge tab can include rotating each of the leading edge clamping member and the trailing edge clamping member into alignment with the respective one of the leading edge tab and the trailing edge tab prior to moving each of the leading edge clamping member and the trailing edge clamping member into engagement.

Moving the leading edge positioning member into engagement can include moving the leading edge positioning member into engagement with the forward side of the leading edge tab to apply a first force. Moving the leading edge clamping member into engagement can include moving the leading edge clamping member into engagement with the aft side of the leading edge tab to apply a second force. The second force can be greater than the first force. Moving the trailing edge positioning member into engagement can include moving the trailing edge positioning member into engagement with the aft side of the trailing edge tab to apply a third force. Moving the trailing edge clamping member into engagement can include moving the trailing edge clamping member into engagement with the forward side of the trailing edge tab to apply a fourth force. The fourth force can be greater than the third force.

Moving the leading edge positioning member into engagement with the forward side of the leading edge tab can include maintaining the leading edge positioning member in a stationary position in response to application of a first threshold amount of force. Moving the trailing edge positioning member into engagement with the aft side of the trailing edge tab can include maintaining the trailing edge positioning member in a stationary position in response to application of a second threshold amount of force.

A fixture system for securing an airfoil during material removal operations includes a root-securing fixture configured to engage a root of the airfoil, a tip-securing fixture configured to be selectively engageable and disengageable from a tip of the airfoil, and a control system. The control system is configured to cause the tip-securing fixture to engage the tip during initial removal of material from the airfoil and to disengage the tip after the initial removal of material to allow movement of the tip from a clamped-state position to a free-state position. The control system is further configured to cause the tip-securing fixture to reengage the tip in the free-state position during additional removal of material from the airfoil.

The fixture system of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations, operations, and/or additional components:

The control system can be configured to cause the tip-securing fixture to engage the tip during the initial removal of material by causing the tip-securing fixture to engage each of a plurality of tabs extending from a radially outer edge of the tip of the airfoil within the tip-securing fixture. The control system can be configured to cause the tip-securing fixture to disengage the tip after the initial removal of material by causing the tip-securing fixture to disengage each of the plurality of tabs from the tip-securing fixture.

The plurality of tabs can include a leading edge tab proximate a leading edge of the airfoil, a trailing edge tab proximate a trailing edge of the airfoil, and a center tab disposed between the leading edge tab and the trailing edge tab. The center tab can have a bore extending radially inward from a radially outer side of the center tab. The tip-securing fixture can include a leading edge clamping assembly configured to be selectively engageable and disengageable from the leading edge tab, a trailing edge clamping assembly configured to be selectively engageable and disengageable from the trailing edge tab, and a centering pin configured to be selectively inserted into and retracted from the bore of the center tab. The control system can be configured to cause the tip-securing fixture to engage each of a plurality of tabs by causing the leading edge clamping assembly to engage the leading edge tab, the trailing edge clamping assembly to engage the trailing edge tab, and the centering pin to insert into the bore of the center tab. The control system can be configured to cause the tip-securing fixture to disengage each of the plurality of tabs by causing the leading edge clamping assembly to disengage from the leading edge tab, the trailing edge clamping assembly to disengage from the trailing edge tab, and the centering pin to retract from the bore of the center tab.

The control system can be configured to cause the tip-securing fixture to reengage the tip in the free-state position during the additional removal of material by causing the leading edge clamping assembly to engage the leading edge tab and the trailing edge clamping assembly to engage the trailing edge tab.

The control system can be configured to cause the tip-securing fixture to reengage the tip in the free-state position during the additional removal of material by maintaining the centering pin in a disengaged state.

The leading edge clamping assembly can include a leading edge positioning member and a leading edge clamping member. The trailing edge clamping assembly can include a trailing edge positioning member and a trailing edge clamping member. The control system can be configured to cause the centering pin to insert into the bore of the centering tab by causing the centering pin to move into the bore of the centering tab. The control system can be configured to cause the leading edge clamping assembly to engage the leading edge tab by causing the leading edge positioning member to move into engagement with a forward side of the leading edge tab and causing the leading edge clamping member to move into engagement with an aft side of the leading edge tab. The control system can be configured to cause the trailing edge clamping assembly to engage the trailing edge tab by causing the trailing edge positioning member to move into engagement with an aft side of the trailing edge tab and causing the trailing edge clamping member to move into engagement with a forward side of the trailing edge tab.

The control system can be configured to cause both the leading edge positioning member and the trailing edge positioning member to move into engagement before causing either of the leading edge clamping member and the trailing edge clamping member into engagement.

The control system can be configured to cause each of the leading edge clamping member and the trailing edge clamping member to move into engagement with the respective one of the leading edge tab and the trailing edge tab by causing each of the leading edge clamping member and the trailing edge clamping member to rotate into alignment with the respective one of the leading edge tab and the trailing edge tab prior to causing each of the leading edge clamping member and the trailing edge clamping member to move into engagement.

The control system can be configured to cause the leading edge positioning member to move into engagement by causing the leading edge positioning member to move into engagement with the forward side of the leading edge tab to apply a first force. The control system can be configured to cause the leading edge clamping member to move into engagement by causing the leading edge clamping member to move into engagement with the aft side of the leading edge tab to apply a second force, the second force greater than the first force. The control system can be configured to cause the trailing edge positioning member to move into engagement by causing the trailing edge positioning member to move into engagement with the aft side of the trailing edge tab to apply a third force. The control system can be configured to cause the trailing edge clamping member to move into engagement by causing the trailing edge clamping member to move into engagement with the forward side of the trailing edge tab to apply a fourth force, the fourth force greater than the third force.

The control system can be configured to cause the leading edge positioning member to remain in a stationary position in response to application of a first threshold amount of force during engagement with the forward side of the leading edge tab. The control system can be configured to cause the trailing edge positioning member to remain in a stationary position in response to application of a second threshold amount of force during engagement with the aft side of the trailing edge tab.