Drilling method, in particular for a turbine shaft of an aircraft turbine engine

Abstract

The invention relates to a drilling method, in particular for a turbine shaft of an aircraft turbine engine, which method is implemented by a drilling machine (100) including a drill rod (8), a cutting tool (4) mounted on a free end of the drill rod, and an anti-vibration ring (10) positioned on the drill rod behind the cutting tool, the anti-vibration ring including a sleeve including a bore extending longitudinally coaxially between a front end and a rear end of the sleeve, as well as a first absorption means positioned in the bore and a second absorption means positioned on an outer circumference of the sleeve, the method including steps of: a) placing the anti-vibration ring on the drill rod near a free end of the drill rod; b) securing the cutting tool to the free end of the drill rod; c) drilling a bore to be made in the turbine shaft by pushing, during which the anti-vibration ring is inserted into an inlet (21) of the bore to be made.

Description

DESCRIPTION TITLE: ANTI-VIBRATION RING FOR DRILLING, PARTICULARLY FOR AN AIRCRAFT TURBINE SHAFT TECHNICAL FIELD OF THE INVENTION

[0001] The invention relates to the field of drilling cylindrical holes in a workpiece. In particular, the invention relates to an anti-vibration ring for drilling, especially for drilling long cylindrical holes of revolution, notably a bore in a turbine shaft of a turbomachine. STATE OF PRIOR ART

[0002] Drilling is a machining operation known in itself that allows a cylinder of revolution to be created in a workpiece by removing material.

[0003] This operation is used in particular to bore a hole in the turbine shaft of a turbomachine. The turbine shaft is a component that transmits torque from the turbine of the turbomachine to the propellers and / or a compressor within the turbomachine. A key characteristic of such a turbine shaft is that it runs the entire length of the turbomachine. The turbine shaft can be long (over 2 meters), narrow (small diameter, around ten centimeters or less), and hollow. The characteristics of the materials (hardness, elasticity, machinability, etc.) used to manufacture the component necessitate the development of machining and holding tools adapted to the drilling stresses, particularly vibration and tool buckling.

[0004] Indeed, during the machining of such a turbine shaft, the cutting forces and the relative movement between the workpiece and the cutting tools generate vibration. This vibration weakens the tools and can lead to breakage. Most often, it is the machining inserts that break and damage the workpiece surface. Furthermore, buckling is the phenomenon of deformation of a bar under stress. Drilling a long hole or bore requires guiding the cutting tool deeply into the workpiece. The stresses applied to the drill bar connecting the cutting tool to a spindle are significant. Training can lead to buckling of the cutting bar, which impacts the guidance of the cutting tool and can generate a geometric defect or even a blockage of the cutting tool in the workpiece.

[0005] The part must then be repaired or, depending on the severity of the damage, may be declared scrap. DESCRIPTION OF THE INVENTION

[0006] One aim of the invention is to provide a tooling, in particular a drilling ring, which can guarantee the correct creation of a long cylindrical hole of revolution by reducing the occurrence of geometric defects and / or tool breakage.

[0007] To this end, according to the invention, an anti-vibration ring for drilling, in particular of an aircraft turbomachine turbine shaft, comprising a sleeve having a bore extending longitudinally coaxially between a front end and a rear end of the sleeve, in which the anti-vibration ring comprises a first absorption means positioned in the bore and a second absorption means positioned on an external circumference of the sleeve.

[0008] Advantageously, but optionally, the device according to the invention has at least one of the following technical characteristics: - the first and second means of absorption include absorption seals; - the anti-vibration ring includes means for circulating a lubricating fluid between the front end and the rear end; - the means of circulation include a bathtub provided in the bore; - the first absorption means is in two parts, the bathtub is provided between the two parts of the first absorption means; - the means of circulation include a series of grooves extending longitudinally over part of the external circumference of the sleeve from at least one of the front and rear ends; - the means of circulation include a series of radial through-holes between the series of grooves and the tub; - the anti-vibration ring also includes, at the rear end, a support rim extending in projection from the outer circumference of the sleeve; - the means of circulation further include axial openings passing through the support edge; and, - the anti-vibration ring is made of polyamide, in particular nylon.

[0009] The invention also provides for a drilling machine, in particular for drilling an aircraft turbomachine turbine shaft, comprising a drill rod, a cutting tool mounted on a free end of the drill rod, in which the machine further comprises an anti-vibration ring positioned on the drill rod, behind the cutting tool, and having at least one of the preceding technical characteristics.

[0010] The invention also provides for an installation comprising a previous drilling machine and an aircraft turbomachine turbine shaft having a bore to be made, the turbine shaft being installed in the drilling machine, in which, during drilling of the bore to be made, the anti-vibration ring is arranged so as to come to rest in an entrance of the bore to be made.

[0011] The invention also provides for a drilling method, in particular for drilling an aircraft turbomachine turbine shaft, implemented by a previous drilling machine, the method comprising the steps of: a) Placing the anti-vibration ring on the drill rod in the vicinity of a free end of the drill rod; b) Fixing the cutting tool on the free end of the drill rod; c) Drilling a bore to be made in the turbine shaft by pushing, during which the anti-vibration ring is inserted into an inlet of the bore to be made. BRIEF DESCRIPTION OF THE FIGURES

[0012] Other features and advantages of the invention will become apparent from the following description of an embodiment of the invention. See the attached drawings: [Fig.1] is a schematic view of a drilling machine comprising an anti-vibration ring according to the invention implemented for making a bore in a long shaft; [Fig. 2] is a three-dimensional cross-sectional view of an anti-vibration ring according to the invention; and, [Fig.3] is a partial cross-sectional view of the anti-vibration ring of figure 2 in place in a bore being machined.

[0013] For clarity, identical or similar elements are identified by identical reference symbols across all figures. DETAILED DESCRIPTION OF A METHOD OF IMPLEMENTATION

[0014] With reference to Figure 1, we will briefly describe an installation for creating a long cylindrical hole of revolution 20, as a bore to be made, in a part 2, such as a turbine shaft. Hereafter, we will refer to reference 2 as the "turbine shaft" and reference 20 as the "bore to be made," without this being restrictive.

[0015] This installation includes a specific drilling machine 100 called a drill rig, in which the turbine shaft 2 is installed. Drilling equipment positioned within the drill rig includes a cutting tool 4, known per se, mounted on one free end of a drill rod 8. The drill rod 8 is itself mounted on a movable headstock 6 comprising a device for rotating the drill rod. The headstock 6 is mounted to slide within the drill rig. While rotating the cutting tool 4 via the drill rod 8, the headstock 6 also pushes on said cutting tool 4 via the same drill rod 8. This allows the bore 20 to be created by a machining operation by pushing within the turbine shaft 2. It should be noted that the rotation of the cutting tool 4 and the drill bar 8 is a cutting parameter when using the installation and it can be set.

[0016] In order to guide the cutting tool 4 in the bore 20 while suppressing the vibrations generated by the drilling operation, the drilling tooling includes an anti-vibration ring 10 according to the invention which we will now describe in more detail with reference to figure 2.

[0017] The anti-vibration ring 10 according to the invention is generally cylindrical in shape and of revolution about a longitudinal axis X. The anti-vibration ring 10 according to the invention thus extends longitudinally between a front end 14 and a rear end 12. The anti-vibration ring 10 according to the invention comprises a sleeve 19 extending between the two front ends 14 and rear ends 12. The sleeve 19 has a bore 17 extending longitudinally coaxially along the longitudinal axis X between the two front ends 14 and rear ends 12. The sleeve 19 further comprises an external circumference 190.

[0018] At the rear end 12, the anti-vibration ring 10 according to the invention includes a support rim 16 extending in projection from the external circumference 190 of the sleeve 19.

[0019] The anti-vibration ring 10 according to the invention comprises a first vibration-absorbing means 15 positioned in the bore 17. Here, the first absorption means 15 is in two parts: a first part is positioned at the front end 14 of the anti-vibration ring 10 according to the invention, and a second part is provided at the rear end 12 of the anti-vibration ring 10 according to the invention. Here, each part of the first absorption means 15 comprises an absorption seal.

[0020] The anti-vibration ring 10 according to the invention further comprises a second vibration-absorbing means 18 positioned on the outer circumference 190 of the sleeve 19. Here, the second absorption means 18 is positioned midway between the front 14 and rear 12 ends of the anti-vibration ring 10 according to the invention. The second absorption means includes an absorption seal. In an alternative embodiment, the second absorption means 18 is located anywhere where between the front ends 14 and rear ends 12 of the anti-vibration ring 10, particularly in the vicinity of one of the front ends 14 and rear ends 12.

[0021] Here, the absorption seals for the first 15 and second 18 absorption methods are O-rings. Other types of seals can be used as long as they can absorb vibrations generated during a drilling operation.

[0022] On the other hand, the anti-vibration ring 10 according to the invention includes means for circulating a fluid 11, 13, 170, 110, in order to allow a circulation F of a lubricant between the front end 14 and rear end 12 of the anti-vibration ring 10 according to the invention during a drilling operation.

[0023] The circulation means here include a tub 170 provided in the bore 17 of the sleeve 19. The tub 170 is positioned between the two parts forming the first absorption means 15.

[0024] The means of circulation further include, here, two series of grooves 13 extending longitudinally over a part of the external circumference 190 of the sleeve 19 from respectively the front end 14 and rear end 12. The series of grooves 13 located at the rear end 12 is extended by a series of axial orifices 110 passing through a thickness of the support rim 16.

[0025] Between each of the series of grooves 13 and the tub 170, the circulation means include radial through orifices 11 provided in a thickness of the sleeve 19 so as to put in fluidic communication each groove 13 and the tub 170.

[0026] Here, the grooves 13, the radial through holes 11 and the axial holes 110 are uniformly distributed over the external circumference 190 of the sleeve 19 of the anti-vibration ring 10 according to the invention.

[0027] The anti-vibration ring 10 according to the invention is here a single piece; the sleeve 19 and the support flange 16 are molded together from one material. For example, the anti-vibration ring 10 according to the invention is made of polyamide such as nylon. Other materials can be used, such as steel or aluminum.

[0028] With reference now to Figure 3, we will briefly describe a use of the anti-vibration ring 10 according to the invention previously described during a drilling process implemented by the drilling machine 100.

[0029] In a first step, the anti-vibration ring 10 according to the invention is slipped onto the drill bit 8 near a free end of said drill bit 8, the latter being slidably and rotatably received in the bore 17 of the sleeve 19. The first absorption means 15 is thus sandwiched between the drill bit 8 and the bore 17. Next, in a second step, the cutting tool 4 is mounted on the free end of the drill bit 8. Here, the cutting tool has guide pads 41 for guiding said cutting tool 4 within the bore to be machined 20 in the turbine shaft 2. Behind the cutting tool 4, the latter has a vibration absorption device comprising a ring 43 and an absorption seal 44. The mounting of the cutting tool 4 onto the drill bit 8 is carried out using a clamping ring 42.

[0030] Next, a drilling step of the bore to be made 20 begins by pushing. The anti-vibration ring 10 according to the invention is positioned on the drill bar so that its front end 14 faces the cutting tool 4. Thus, during the drilling step, as the drilling tool advances P, the front end 14 is inserted into an opening 21 of the bore to be made 20, the sleeve 19 penetrating said bore to be made 20 until the support rim 16 comes into contact with the turbine shaft 2, at the level of said opening 21 of the bore to be made 20. The second absorption means is then sandwiched between the bore to be made 20 and the sleeve 19.

[0031] The anti-vibration ring 10 according to the invention is then in position, and the drill rod continues to slide and rotate within the anti-vibration ring 10 according to the invention to continue the drilling operation. Thus, the drill rod 8 is guided, which reduces the risk of buckling. Furthermore, the first 15 and second 18 absorption means help to "break" a amplification of the generated vibrations and therefore to reduce possible machining defects, or even breakage of the cutting tool 4. Finally, the circulation means 11, 13, 170, 110 allow the circulation of a cutting lubricant towards the outside of the bore to be made 20.

[0032] The use of such an anti-vibration ring 10 according to the invention allows a significant reduction in non-conformities and / or scrap parts by eliminating non-conformities related to wear or breakage of the cutting tool 4, eliminating the risk of the cutting tool 4 seizing in the bores, and reducing the risk of scrap by avoiding a runout defect during drilling.

[0033] It should be noted that the anti-vibration ring 10 according to the invention was described in the context of drilling a bore within a turbomachine turbine shaft. The anti-vibration ring 10 according to the invention can be used for drilling any long cylindrical hole of revolution in any type of workpiece.

[0034] Naturally, the invention described above is by way of example. It is understood that a person skilled in the art is capable of carrying out different embodiments of the invention without departing from its scope.

[0035] It is emphasized that all features, as they are apparent to a person skilled in the art from the present description, drawings and attached claims, even if in practice they have only been described in relation to other specific features, both individually and in any combinations, may be combined with other features or groups of features disclosed herein, provided that this has not been expressly excluded or that technical circumstances render such combinations impossible or meaningless.

Claims

DEMANDS 1. A drilling method, in particular for drilling an aircraft turbomachine turbine shaft, carried out by a drilling machine (100) comprising a drill rod (8), a cutting tool (4) mounted on a free end of the drill rod and an anti-vibration ring (10) positioned on the drill rod, behind the cutting tool, the anti-vibration ring comprising a sleeve (19) having a bore (17) extending longitudinally coaxially between a front end (14) and a rear end (12) of the sleeve, as well as a first absorption means (15) positioned in the bore and a second absorption means (18) positioned on an external circumference of the sleeve, the method comprising steps of: a) Placing the anti-vibration ring on the drill rod in the vicinity of a free end of the drill rod; b) Fixing the cutting tool onto the free end of the drill bar;c) Drilling a bore to be made in the turbine shaft by pushing, during which the anti-vibration ring is inserted into an inlet (21) of the bore to be made.; 2. Drilling method according to claim 1, wherein the first and second absorption means comprise absorption joints.

3. Drilling method according to any one of claims 1 to 2, wherein the anti-vibration ring comprises means for circulating (11, 13, 170) a lubricating fluid between the front end and the rear end.

4. Drilling method according to claim 3, wherein the circulation means comprise a tub (170) provided in the bore.

5. Drilling method according to claim 4, wherein the first absorption means is in two parts, the tub (170) is provided between the two parts of the first absorption means.

6. A drilling method according to any one of claims 3 to 5, wherein the circulation means comprise a series of grooves (13) extending longitudinally over a portion of the outer circumference of the sleeve from at least one of the front and rear ends.

7. Drilling method according to any one of claims 4 to 5 and claim 6, wherein the circulation means comprise a series of radial through holes (11) between the series of grooves and the tub.

8. A drilling method according to any one of claims 1 to 7, wherein the anti-vibration ring further comprises, at its rear end, a support flange (16) projecting from the outer circumference of the sleeve.

9. A drilling method according to claim 8 and any one of claims 3 to 7, wherein the circulation means further comprise axial orifices (110) passing through the support flange.

10. Drilling method according to any one of claims 1 to 9, wherein the anti-vibration ring is made of polyamide, in particular nylon.

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