Method of restoring a wheel to compliance and tooling for performing the method

Abstract

A method of restoring a wheel (1) to compliance, the wheel having a plurality of ovalized bores (2). The method is characterized in that it includes at least a step of boring a first ovalized bore (2) with the help of a reamer (3) presenting a longitudinal pilot portion (3a) and a longitudinal cutter portion (3b), the cutter portion (3b) presenting teeth (4) defining a cutting diameter (D2), and the pilot portion (3a) presenting a pilot diameter (D1) strictly less than the cutting diameter (D2), the step of boring this first ovalized bore (2) consisting in inserting the reamer (3) into the first ovalized bore (2), beginning with the pilot portion (3a) and followed by the cutter portion (3b), the pilot diameter (D1) being such that it enables the reamer (3) to be guided in translation inside the first ovalized bore (2) for boring.

Claims

1. A method of restoring a wheel (1) to compliance, the wheel having a plurality of ovalized bores (2), the method comprising: boring a first ovalized bore (2) with a reamer (3) presenting a longitudinal pilot portion (3a) and a longitudinal cutter portion (3b), the cutter portion (3b) presenting teeth (4) defining a cutting diameter (D2), and the pilot portion (3a) presenting a pilot diameter (D1) strictly less than the cutting diameter (D2), the step of boring said first ovalized bore (2) consisting of inserting the reamer (3) into the first ovalized bore (2), beginning with the pilot portion (3a) and followed by the cutter portion (3b), the pilot diameter (D1) being such that it enables the reamer (3) to be guided in translation inside the first ovalized bore (2) for boring, the method further comprising, prior to the step of boring the first ovalized bore (2), extracting a ring (6) engaged in the first ovalized bore (2), said extraction step being performed with an extractor tool (7) comprising a pin (8) presenting a longitudinal guide portion (8a) adapted to slide in the ring (6), said pin (8) presenting a bearing portion (8b) shaped to be able to come to bear against an axial end (6a) of the ring (6) while the guide portion (8a) is positioned inside the ring (6) and, in reaction to a compression force (F1) of said bearing portion (8b) against said axial end (6a) of the ring, to cause the bearing portion (8b) to exert radial compression forces (F2) on the ring directed towards a main axis of symmetry (Y-Y) of the ring (6), wherein the longitudinal guide portion (8a) is a right cylinder, the bearing portion (8b) presents a frustoconical surface (S1) on the same axis as the longitudinal guide portion (8a), the frustoconical surface (S1) extends around the longitudinal guide portion (8a), the frustoconical surface (S1) being arranged so as to define an annular hollow zone (Z1) between the frustoconical surface (S1) and the longitudinal guide portion (8a) that is surrounded by said frustoconical surface (S1), and wherein said extracting step is performed by moving the pin (8) so as to force the bearing portion (8b) of the pin (8) against the ring (6) and so as to generate said compression force (F1) of said bearing portion (8b) against said axial end (6a) of the ring.

2. The method of restoring compliance according to claim 1, wherein the reamer (3) extends along a longitudinal axis of symmetry (X-X) of the reamer, and during the boring step, the reamer (3) is assembled to a rotary drive machine (5) arranged to drive the reamer (3) in rotation about said longitudinal axis (X-X) of symmetry of the reamer, the rotary drive machine (5) being manually portable.

3. The method according to claim 2, wherein the ring (6) is in the form of a right cylinder and presents an outside diameter (D3) less than the cutting diameter (D2) defined by the teeth (4) of the reamer, the boring step being performed in such a manner as to bore the first ovalized bore (2) so as to give it a right cylindrical inside shape of diameter equal to the cutting diameter (D2), and then after performing the step of boring the first ovalized bore (2), the method of restoring compliance includes a step of engaging a corresponding replacement ring in each bore (2) that has been bored during the boring step.

4. The method according to claim 1, wherein the ring (6) is in the form of a right cylinder and presents an outside diameter (D3) less than the cutting diameter (D2) defined by the teeth (4) of the reamer, the boring step being performed in such a manner as to bore the first ovalized bore (2) so as to give it a right cylindrical inside shape of diameter equal to the cutting diameter (D2), and then after performing the step of boring the first ovalized bore (2), the method of restoring compliance includes a step of engaging a corresponding replacement ring in each bore (2) that has been bored during the boring step.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other characteristics and advantages of the invention appear clearly from the following description made by way of non-limiting indication and with reference to the accompanying drawings, in which:

(2) FIG. 1 shows an aircraft wheel-half with tooling of the invention positioned relative thereto in order to extract rings engaged in ovalized bores in the rim and in order to re-bore these ovalized bores;

(3) FIG. 2 is a fragmentary section view of the FIG. 1 wheel-half while the ring extractor tool of the invention is in use for extracting a ring from an ovalized bore;

(4) FIG. 2A is a detail views of FIG. 2 showing a cone forming part of the ring extractor tool and adapted to opening up the end of the bore through which the ring is to be extracted;

(5) FIG. 2B is a detail view of FIG. 2A while a ring-extraction force is being applied;

(6) FIG. 3 is a perspective view of the reamer of the invention; and

(7) FIG. 4 is a fragmentary section view of the FIG. 1 wheel-half when the reamer is inserted into a bore in order to eliminate its ovalization.

DETAILED DESCRIPTION OF THE INVENTION

(8) The method of the invention of restoring compliance is applied in this example to restoring an aircraft landing gear wheel 1 to compliance. The aircraft wheel 1 is made up of two wheel-halves, each of which is annular and extends along a wheel axis of revolution A-A. FIG. 1 shows an aircraft wheel-half 1 having a plurality of bores 2 extending parallel to the axis of revolution A-A of the wheel-half 1. The wheel-half 1 is rotatably mounted on a machining jig to rotate about an axis of rotation that is substantially horizontal in order to make it easier to bring the bores 2 up to the height of an operator.

(9) These bores 2 may be designed to enable the wheel-half 1 to be assembled to brake means for the purpose of transmitting braking torque from the wheel. As a result of repeated braking operations, and given the large forces that are transmitted via these bores 2, it is found that the bores 2 become internally deformed and the bores 2 tend to be ovalized. A bore 2 as deformed in this way is not cylindrical and it is referred to as an ovalized bore. Each ovalized bore leads to a poor fit and to slack between the wheel-half 1 and the brake parts it receives. This can lead to vibration and to the risk of premature fatigue in the parts of the aircraft landing gear.

(10) For economic reasons, instead of systematically discarding wheel-halves presenting ovalized bores, it is preferred to restore them to compliance. Over its lifetime, a given wheel-half 1 can be restored to compliance on several occasions.

(11) Restoring a wheel-half to compliance comprises re-boring the ovalized bores 2, and if the wheel-half has already been restored to compliance, extracting the rings engaged in each of the previously re-bored bores.

(12) Under all circumstances, after re-boring, it is necessary to engage a new replacement ring in the re-bored bore. Such a replacement ring (not shown) has a hollow inside shape in the form of a right cylinder of inside diameter that is substantially identical to the original inside diameter of the bore, i.e. the diameter that the bore had prior to first use of the wheel-half. Each replacement ring has an outside shape in the form of a right cylinder of outside diameter equal to the inside diameter of the re-bored bore plus or minus tolerance needed for achieving a tight fit between the replacement ring in the re-bored bore.

(13) It should be observed that the same steps of ring extraction, of re-boring, and of engaging a replacement ring are performed for each of the ovalized bores in the wheel-half.

(14) In more detailed manner, in a first aspect, the invention relates to a method of restoring a wheel-half 1 to compliance, which method includes at least a step of re-boring each of the ovalized bores 2 in the wheel-half, using a reamer 3 presenting longitudinally a pilot portion 3a and a cutter portion 3b. The cutter portion 3b has teeth 4 that define a cutting diameter D2, and the pilot portion 3a presents a pilot diameter D1 that is strictly smaller than the cutting diameter D2. For each ovalized bore, this boring step consists in inserting the reamer 3 into the ovalized bore 2, beginning with its pilot portion 3a and followed by the cutter portion 3b. The pilot diameter D1 is designed to guide the reamer 3 in translation in the ovalized bore 2 for boring. A manually portable rotary drive machine 5 for driving the reamer 3 is assembled to the reamer in order to drive it in rotation about a longitudinal axis of symmetry X-X along which the reamer 3 extends.

(15) When the ovalized bore already contains an internal ring, then prior to performing the boring step, it is necessary to perform a step of extracting the ring 6 that is engaged in the ovalized bore 2. This extraction step is performed using an extractor tool 7 having a pin 8 presenting a longitudinal guide portion 8a that is adapted to slide inside the ring 6. The pin 8 also has a bearing portion 8b shaped to be capable of coming to bear against an axial end 6a of the ring 6 when the guide portion 8a is slid inside the ring 6.

(16) For this purpose, the longitudinal guide portion 8a is a right cylinder and the bearing portion 8b presents a frustoconical surface S1 on the same axis as the longitudinal guide portion 8a. This frustoconical surface S1 extends around the longitudinal guide portion 8a and is arranged to define an annular hollow zone Z1 between the frustoconical surface S1 and the longitudinal guide portion 8a surrounded by said frustoconical structure S1. The frustoconical surface S1 is defined by an angle X of 86 between the axis of revolution and/or of symmetry X-X of the reamer 3 and the surface S1. This surface S1 can be seen in detail in FIGS. 2A and 2B. Ideally, the end of the ring 6 for extraction presents an external conical chamfer against which the surface S1 comes into abutment. This ensures that concentric radial forces F2 are generated during extraction. These forces F2 limit expansion of the ring and reduce the risk of tearing out material from the bore 2. As can be seen in FIG. 2B, the hollow zone Z1 is conserved in part between the ring 6 and the bearing portion S1. This encourages conical axial contact between the bearing portion and the ring.

(17) Thus, in reaction to a compression force F1 from the bearing portion 8b against the axial end 6a of the ring, the bearing portion 8b exerts radial compression forces F2 on the ring that are directed towards the main axis of symmetry Y-Y of the ring 6, which is of right cylindrical shape.

(18) The outer diameter D3 of the ring 6 is less than the cutting diameter D2 of the reamer so that when the reamer is driven in rotation about the axis X-X, each of the ovalized bores has a right cylindrical inside shape imparted thereto of diameter equal to the cutting diameter D2.

(19) There follows a description in detail of the tooling 9 of the invention that enables the method of the invention to be performed.

(20) The tooling 9 comprises a reamer tool 10 and an extractor tool 7 for extracting the ring 6 engaged in the bore 2.

(21) The reamer tool 10 comprises the reamer 3 which presents in succession: its longitudinal pilot portion 3a; its longitudinal cutter portion 3b; and its longitudinal rotary drive portion 3c. The pilot portion 3a extends along a right cylindrical surface defining the pilot diameter D1. The longitudinal cutter portion 3b is placed between the longitudinal pilot portion 3a and the longitudinal rotary drive portion 3c.

(22) Thus, the reamer 3 enables the rotary drive machine 5 to be positioned relative to the bore 2.

(23) For this purpose, the longitudinal pilot portion 3a presents a centering length that is not less than five times the pilot diameter D1 (this pilot diameter D1 is the maximum outside diameter of the longitudinal pilot portion).

(24) The longitudinal pilot portion 3a presents mutually parallel grooves 11, each having a lateral side 11c and terminal ends 11a, 11b that open out respectively towards the outside of the reamer 3. The grooves 11 are parallel to the longitudinal axis of symmetry X-X of the reamer and they enable the inside of the bore to be scraped in order to move any debris. The debris is evacuated via the longitudinal grooves 11 prior to cutting. This: limits any risk of the reamer 3 jamming inside the bore 2; limits wear to the cutter portion 3b; and improves centering of the reamer in the ovalized bore.

(25) In order to facilitate penetration and centering of the cutter portion relative to the bore, this portion presents a chamfered entry profile for its teeth.

(26) The teeth 4 of the reamer 3, which define the cutting diameter D2, are typically four in number and they are distributed regularly around the longitudinal axis of symmetry of the reamer 3. One of the teeth 4a is not sharp and it set back relative to the cutting diameter D1 defined by the other teeth 4 of the reamer. The setback is typically 0.15 mm0.05 mm relative to the cutting diameter.

(27) Because of the setback characteristic, the tooth 4a that is not sharp creates an abutment opposing the reamer advancing too quickly into the bore. This makes it possible to ensure that the forward speed is substantially constant regardless of the thrust applied to the reamer. This makes it possible to obtain the thrust force merely from the force applied by the operator, without using any external mechanical means for regulating advance.

(28) The use of helical teeth 4 in combination with the tooth 4a enables the reamer 3, once set into rotation about its axis X-X, to penetrate on its own into the bore while limiting its speed of advance. The advance of the reamer is automatically regulated, which facilitates the reamer being used by an operator, who need not be highly qualified.

(29) As shown in FIG. 1, the extractor tool 7 includes the pin 8 and a machine 7a for driving the pin 8 to move in translation relative to the wheel-half 1 along a longitudinal axis Z-Z of symmetry of the pin 8.

(30) As can be seen in FIG. 2, this machine 7a includes a hydraulic actuator 7c that is hollow along its entire length to allow the pin 8 to pass through the actuator 7c. The pin 8 enables the actuator 7c to be positioned and/or located relative to the bore 2 in which there is the ring 6 that is to be extracted.

(31) Thus, the pin 8 serves to guide the extractor tool 7 relative to the ring that is to be extracted, thereby facilitating extraction without requiring a hydraulic press with a fixed stand. The longitudinal guide portion 8a of the pin 8 is arranged between the bearing portion 8b and the end 8c of the pin, which is connected to the actuator via a nut 13.

(32) Thus, the pin 8 passes through the ring 6 and presents its longitudinal guide portion 8a placed in the ring 6, its bearing portion 8b placed on one side of the ring, and the drive machine 7 placed at the other side of the ring 6 in order to exert the traction force F1.

(33) The drive machine 7 also presents an annular bearing part 12 that extends along the pin 8 and that presents an internal passage 12a adapted to receive the ring 6. This annular bearing part 12 presents a cone 14 at one of its axial ends for coming into contact against the wheel-half 1 and around the bore 2, at the location of an annular chamfer formed at the outlet from the bore. This cone 14 is shaped to spread open the chamfered end of the bore 2 when it is forced against the chamfer. This serves to limit any risk of tearing away material when extracting the ring.

(34) It should be observed that by using the portable tooling of the invention and by using the method of the invention, it is possible to avoid using non-portable machines with fixed stands, such as a reaming machine or a hydraulic press.

(35) The tooling 9 is used as follows:

(36) A) initially, the pin 8 is inserted in the bore 2 from one side of the wheel-half 1 (from a hollow side of the wheel-half), via its threaded end 8c until the threaded end 8c passes through the wheel-half);

(37) B) secondly, the following are engaged on the pin 8: firstly the annular bearing part 12 so that its conical portion 14 can press against the internal conical chamfer of the bore 2; then the hollow actuator 7c so that it comes to bear against the part 12 while surrounding the guide portion 8a; and then the nut 13 is screwed onto the threaded end 8c; and

(38) C) thirdly, the hydraulic actuator is powered to generate the force F1 for extracting the ring. At one end, the ring is compressed concentrically and at its other end the bore 2 is spaced apart by the cone 14. The ring is thus extracted from the bore while limiting any risk of damaging the bore.

(39) After the rings have been extracted, each of the bores 2 is re-bored with the reamer 3, and then the replacement rings are engaged in each of the re-bored bores. The wheel-half is then considered as being restored to compliance.

(40) The invention is not limited to the above-described examples and covers other embodiments that are not described. In particular, although the invention relates to tooling 9 combining a boring tool 10 and an extractor tool 7, the invention may also relate to the reamer 3 on its own or to the extractor tool 7 on its own.