Deburr Tool

This disclosure generally pertains to a deburr tool for removing burrs from the interior of a tube, particularly, a non-straight tube such as a Piccolo tube in an aircraft engine inlet assembly.

Occasionally, there is a need to remove burrs from the interior of a non-straight tube. For example, some aircraft engines employ Piccolo tubes to blow hot bleed air from the engine to the back side of the inlet lip skin to prevent ice from forming on the lip skin. Piccolo tubes comprise a plurality of outlet holes that are formed by drilling. It is desirable to remove burrs from the Piccolo tube that were created during the drilling process.

Referring to, an inlet assemblyfor an aircraft engine nacelle comprises a Piccolo tube. The Piccolo tubehas a generally circular outlet sectiondisposed around the engine intakeand an inlet neckextending rearward from the outlet section. Between the inlet neckand the outlet section, there are two right angle turns (one to the left portion of the outlet section and the other to the right portion of the outlet section). Numerous holes are drilled in the outlet sectionso that hot bleed air imparted through the inlet neck will be discharged from the holes toward the back side of the inlet lip of the nacelle, thereby keeping it warm and free of ice.

Internal burrs form when the holes are drilled in the outlet section. It is desirable for these burrs to be removed at the factory prior to installation of the Piccolo tubein the engine inlet assembly. But when the Piccolo tubeis not properly deburred prior to aircraft engine assembly, there is a need for a tool that can deburr the Piccolo tube in situ, without disassembling the aircraft engine inlet assemblyfor access to the Piccolo tube. Existing tools are unable to successfully navigate the turn from the inlet neckto the outlet sectionand then reliably engage the inner wall of the outlet section to remove the burrs.

In one aspect, a deburr tool comprises a flexible drive shaft having an axis of rotation and a proximal end portion and a distal end portion spaced apart along the axis of rotation. The proximal end portion of the flexible drive shaft is configured to couple to a prime mover such that the prime mover can drive rotation of the flexible drive shaft about the axis of rotation. An expandable burr removal head comprises a burr removal element. The expandable burr removal head is selectively adjustable between a collapsed configuration in which the burr removal element is radially spaced apart from the axis of rotation by a first radial dimension and an expanded configuration in which the burr removal element is radially spaced apart from the axis of rotation by a second radial dimension greater than the first radial dimension. The expandable burr removal head is operatively coupled to the distal end portion of the flexible drive shaft such that the burr removal element rotates with the flexible drive shaft about the axis of rotation.

In another aspect, a method of deburring a Piccolo tube installed in a preassembled aircraft engine comprises inserting a deburr tool through an inlet neck of the Piccolo tube until an expandable head of the deburr tool is located inside an outlet section of the Piccolo tube. The expandable burr removal head is expanded inside the outlet section of the Piccolo tube. A flexible shaft of the deburr tool is driven in rotation to rotate the expanded expandable burr removal head inside the outlet section of the Piccolo tube.

Other aspects and features will be apparent hereinafter.

Corresponding parts are given corresponding reference numbers throughout the drawings.

The inventor believes that a better tool is needed to remove burrs from the interior of a non-straight tube such as a Piccolo tube. As explained more fully below, this disclosure generally pertains to a tool that is capable of deburring a Piccolo tube in situ in a pre-assembled aircraft engine assembly. Those skilled in the art will also recognize that the tool disclosed herein could be useful for deburring the interior of other non-straight tubes. As explained more fully below, the tool is able to collapse to fit through the right angle turn from the inlet neckto the outlet sectionof the Piccolo tubeand then the tool can be selectively expanded inside the outlet section to properly engage the inner wall of the outlet section for removing internal burrs.

Referring to, an exemplary embodiment of a deburr tool in accordance with the present disclosure is generally indicated at reference number. The deburr toolbroadly comprises a flexible drive shaftand an expandable burr removal head. The flexible drive shaftis sufficiently flexible and of sufficient length (i) to allow the expandable burr removal headto be inserted through the inlet neckof a 2 inch diameter Piccolo tube, (ii) for the expandable burr removal headto subsequently make the right angle turn from the inlet neckinto the outlet section, and (iii) after making the turn, to pass through the lumen of the outlet section along at least about half the circumference of the outlet section (which allows the toolto cover the entire circumference of the outlet sectionby making the turn from inlet neck to outlet section in both directions). The expandable burr removal headis broadly configured to adjust between a collapsed configuration () and an expanded configuration (). In the collapsed configuration, the burr removal headhas a relatively small collapsed effective diameter ED() for traveling through the lumen of the Piccolo tube, particularly, for making the right angle turn from the inlet neckto the outlet sectionof the Piccolo tube. In the expanded configuration, the burr removal headhas a greater expanded effective diameter ED(), such that the burr removal head is configured to press outward against the inner wall of the Piccolo tube. The flexible drive shaftis configured to be coupled to a drill (broadly, a prime mover) so that the flexible drive shaft drives rotation of the expanded burr removal headinside the Piccolo tube, whereby the burr removal head removes burrs from the inside of the outlet sectionas it moves along the circumference of the Piccolo tube.

In one or more embodiments, the expanded effective diameter EDis at least 0.75 inches (1.9 cm) greater than the collapsed effective diameter ED. In certain embodiments, the collapsed effective diameter EDis in an inclusive range of from 1 inch (2.5 cm) to 1.5 inches (3.8 cm). The expanded effective diameter EDcan be in an inclusive range of from 2.25 inches (5.7 cm) to 2.75 inches (7.0 cm).

The flexible drive shafthas an axis of rotation RA () and a proximal end portion and a distal end portion spaced apart along the axis of rotation. The proximal end portion of the flexible drive shaftis configured to couple to a drill (not shown) such that the drill can drive rotation of the flexible drive shaft about the axis of rotation RA. The flexible drive shafthas a contiguous flexible length of at least 6 feet (e.g., at least 7 feet or at least 8 feet). The flexible drive shaft is flexible along essentially the entire contiguous flexible length, with the exception of very short sections (less than 5% of the overall length) where short rigid components such as an adjustment collar() or an end-to-end coupler (not shown) for joining two flex shafts together are located.

The flexible drive shaftcomprises a flexible drive coiland a flexible sheathencasing a length of the flexible drive coil. The flexible sheathis movable (axially) in relation to the flexile drive coilbetween a retracted position () and an extended position (). As explained more fully below, the flexible sheathis operatively coupled to the expandable burr removal headsuch that the flexible sheath can adjust the expandable burr removal head from the collapsed configuration to the expanded configuration as the flexible sheath moves from the retracted position to the protracted position.

Referring to, the adjustment collaris configured to facilitate manual adjustment of the flexible sheathfrom the retracted position to the extended position and for locking the sheath in place in each position. The collarbroadly comprises a collar body, a sheath coupling, a coil bearing, and a set screw. The sheath couplingcouples the collar bodyto a proximal end portion of the flexible sheathso that the flexible sheath moves axially with the collar body in relation to the flexible coil. In the illustrated embodiment, the proximal end portion of the flexible sheathis formed with key slotsthat mate with internal keysin the collar body. These keying features,link the flexible shaft and collartogether for conjoint rotation about the axis of rotation RA. The coil bearingfits over the coiland provides a bearing surface for the collaras it moves axially along the coil to extend and retract the flexible sheath. The coil bearingalso defines a threaded openingfor threadably coupling to the set screw. The set screw is configured to be threaded into the openingto tighten against the flexible coil, whereby the set screwlocks the collar(and thus the flexible sheath) in an axial position (e.g., retracted or extended) relative to the coil. The tightened set screwalso links the collar(and thus the flexible sheath) to the flexible coilfor conjoint rotation with the flexible coil. To adjust the axial position of the collarand flexible sheath, the set screwis loosened.

Referring again to, the expandable burr removal headbroadly comprises a burr removal element (e.g., a hone stone). In the illustrated embodiment, the burr removal headcomprises three burr removal elements (hone stones) spaced apart circumferentially about the axis of rotation RA. More particularly, the burr removal headcomprises three hone stones, similar to the hone stones used in brake cylinder hones for automotive repair. In comparison with the hone stones used in a brake cylinder hone, the hone stonesare notably shorter in length. Each hone stone has an entire length L() less than 1 inch (2.5 cm). In addition, the edges and corners of the hone stonesare rounded to minimize scarring and gouging inside the Piccolo tube. The hone stoneshave mildly abrasive outer surfaces that are configured to lightly abrade the inner wall of the Piccolo tubeas the burr removal headrotates while expanded. This allows the hone stonesto remove burrs from the interior of the Piccolo tubewithout damaging the Piccolo tube. In the collapsed configuration (), the hone stonesare radially spaced apart from the axis of rotation RA by a first radial dimension RD(; e.g. one-half of ED), and in the expanded configuration, the hone stonesare radially spaced apart from the axis of rotation by a second radial dimension RD(; e.g., one-half of ED) greater than the first radial dimension. The effective diameters ED, EDare equal to the diameter of a circle formed when a point along the outer surface of one of the hone stones is rotated 360° about the axis of rotation

In the illustrated embodiment, the expandable burr removal headis adjusted between the retracted and expanded configurations by a mechanism similar to that of a brake cylinder hone. Thus, the expandable burr removal headcomprises a hub() fastened to the drive coil for rotation with the drive coil about the axis of rotation RA, a plurality of hone armspivotably connecting the hub to the hone stones, a cone membermovable in relation to the drive coil between a first position () and a second position () to adjust the expandable burr removal headbetween the retracted configuration and the expanded configuration, and a springconfigured to be loaded between the flexible sheathand the cone member when the flexible sheath is in the extended position.

The hubcomprises an annular central portioncentered on the axis of rotation RA and three hone arm spokesextending radially outward from the annular central portion. The annular central portionincludes one or more threaded openingsconfigured to threadably couple to set screwsthat affix the hubto the flexible drive coil. Pinscouple the hone arm spokesto the hone armssuch that the hone arms can pivot in relation to the hub.

Each hone armhas a proximal end portion and a distal end portion. A first pivot pointis located between the proximal end portion and the distal end portion and a second pivotpoint is located at the distal end portion thereof. A pinpivotably connects each hone armto the hubat the respective first pivot point, and a pin-shaped fastenerpivotably couples each hone stonea respective hone arm at the second pivot point. In the illustrated embodiment, each pin-shaped fastenercomprises a screw fastened in place with a nut. Each home armhas an effective length L() extending from the respective first pivot pointto the respective second pivot point, and the effective length Lof each hone arm is less than 1.1 inches (2.8 cm). This is considerably less than the corresponding distance in a brake cylinder hone and is one parameter that contributes to low profile so that the expandable burr removal headcan traverse the lumen of a 2 inch (5.1 cm) diameter Piccolo tube. Near the proximal end portion of each hone arm, the outer surface of the hone harm has a convexly curved shape that is configured for camming engagement with the cone member.

The cone memberhas an interior (conical) surface (see) and an exterior (conical) surface. The springcomprises a compression spring (e.g., a cone-shaped compression spring) with a proximal end portion operatively coupled to the flexible sheathand a distal end portion engaging the exterior of the cone member. When the flexible sheathmoves distally from the retracted position to the extended position, it moves the springdistally, which in turn moves the cone memberdistally from the first position to the second position. For example, a bearingon the distal end portion of the flexible sheath engages the proximal end portion of the springand thereby moves the spring and the cone memberdistally. Hence, the cone memberis operatively connected to the flexible sheathsuch that the flexible sheath drives movement of the cone member from the first position toward the second position as the flexible sheath moves from the retracted position to the extended position. The interior of the cone memberbears against the outer convex camming surfaces of the proximal end portions of the hone armsas the cone membermoves distally from the first position to the second position. As the cone membermoves distally from the first position to the second position, the interior of the cone memberpivots the hone armsabout the first pivot pointsin an outward rotational direction to adjust the burr removal head from the collapsed configuration to the expanded configuration.

When this occurs, the springis loaded between the flexible sheathand the cone membersuch that the spring yieldably biases the cone member distally toward the second position. As the hone stonescome into contact with the inner wall of the Piccolo tube, the springcan yield to allow the cone memberto move proximally in relation to the flexible drive shaft. This yielding ensures the hone stonesengage the inner wall of the Piccolo tubewith the proper amount of force and allows for some retraction of the expandable burr removal headfrom the fully expanded position when it encounters restrictive geometry or other obstacles inside the Piccolo tube.

In the illustrated embodiment, the expandable burr removal headfurther comprises a nose conecoupled to the hub. The nose conecomprises a tapered distal section extending distally from the hub. The tapered distal section of the nose coneis configured to provide clearance for some pivoting of the hone stoneswhen the burr removal headis expanded. But the tapered distal section of the nose conewill also interfere with pivoting movement to a fully inverted orientation in which the abrasive surface of the hone stone would face inward. If the hone stoneswere to fully invert during use, it may restrict removal of the deburr toolfrom the Piccolo tube.

Unlike a brake cylinder hone, the illustrated burr removal headfurther comprises a resilient memberfor yieldably biasing the burr removal head toward the collapsed configuration. More particularly, the illustrated resilient memberis an elastic band disposed around the plurality of hone armssuch that the elastic band yieldably biases the plurality of hone arms inward about the first pivot points. In the illustrated embodiment, the elastic bandis threaded through openings in the inner proximal end portions of the hone stones. The elastic bandis thought to provide particular advantage for using the deburr toolinside a non-straight tube because it forces the burr removal headtoward the collapsed configuration when the flexible sheathis retracted. Without the elastic bandthe burr removal headwould have a tendency to remain expanded even after the sheathis retracted, which would make it difficult to withdraw the tool from a Piccolo tube (or other non-straight tube) after deburring.

An exemplary method of using the deburr toolfor deburring a Piccolo tubewill now be briefly described. Referring to, in some embodiments, the method begins with a technician inserting a redirection guideinto the inlet neckof the Piccolo tube. The redirection guidedefines a smoothly curved guide surfacealong which the expandable headof the deburr toolcan slide as it makes a right angle turn from the inlet neckto the outlet sectionof the Piccolo tube.

As shown in, with the expandable headcollapsed, the technician inserts the deburr toolthrough the inlet neckof the Piccolo tube(head first). The expandable headslides along the guide surfaceand makes the right angle turn from the inlet neckto the outlet sectionof the Piccolo tube. At this time, the technician may remove the redirection guidefrom the inlet neckof the Piccolo tube.

As shown in, the technician then uses the collar(not visible in) to extend the flexible sheath, which expands the expandable burr removal head(as explained above) inside the outlet sectionof the Piccolo tube. The technician tightens the set screwof collarto secure the expandable burr removal headin the expanded configuration, then uses a drill to rotate the expanded expandable burr removal headinside the outlet section of the Piccolo tube. The technician moves the tool axially so that the rotating burr removal headtravels along half the circumference of the outlet sectionand removes the burrs from that segment of the outlet section.

Subsequently, the expandable burr removal headcan be collapsed (by loosening the set screwand retracting the flexible sheath) and removed from the Piccolo tube. The guidecan then be reinserted so that the surfaceturns toward the other half-circumference of the Piccolo tube, and the steps for using the deburr toolcan be repeated for the other half of the outlet section.

Accordingly, it can be seen that the deburr toolis able to remove burrs from the interior of a non-straight tube such as a Piccolo tubein situ, e.g., in a pre-assembled aircraft engine assembly. The toolprovides an expandable burr removal headthat is biased toward a collapsed configuration, but which can be selectively expanded from a remote location outside of the Piccolo tube. Thus, the expandable burr removal headcan navigate the right angle turn from the inlet neckto the outlet sectionof the Piccolo tube while collapsed. Then the headcan be expanded inside the outlet sectionand rotate while expanded for removing internal burrs. Finally, the headcan collapse while still located within the outlet section so that it can be withdrawn from the Piccolo tube in the collapsed configuration without getting hung up as it navigates backward from the outlet section to the neck.

When introducing elements of the present disclosure or the preferred embodiment(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.

In view of the above, it will be seen that the several objects of the disclosure are achieved and other advantageous results attained.

As various changes could be made in the above products and methods without departing from the scope of the disclosure, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.