Method for repairing a forging tool insert by die forging

Abstract

A method for repairing a forging tool insert (1) by die forging, the insert comprising a portion to be repaired having an outer surface (S1) having a first geometric profile, the method comprising: a step of removing the portion to be repaired from the rest of the insert and forming a mounting surface (3) on the rest of the insert, the mounting surface (3) comprising an outer surface (S3) formed by a central zone (3a) and a peripheral zone (3b) that gradually extends from the central zone (3a) to the outer surface (S2) of the rest of the insert; and a step of adding metal to the removed portion to be repaired by laser metal deposition using additive manufacturing. Figure for the abstract: Fig 2

Description

Title of the invention: Method for repairing a forging tool insert by die forging. Technical field

[0001] The present invention relates to the technique of forging by hot die forging, in particular for hot die forging, for the manufacture of a metal part and, more particularly, to the repair of an insert for hot die forging.

[0002] More specifically, the invention relates to a method for repairing a tooling insert for forging by die forging. Previous techniques

[0003] Die forging consists of forming a part by plastic deformation of a blank heated to an appropriate temperature. The blanks are generally made of non-ferrous alloys such as aluminum, copper, titanium, nickel, etc.

[0004] Die forging is therefore a forging operation carried out using tooling comprising dies, also called inserts: an upper half-insert and a lower half-insert that are brought together. The inserts are engraved in the shape of the part to be produced.

[0005] In the field of aeronautical turbomachinery, this forging technique is used to manufacture, in particular, turbine discs.

[0006] The inserts used for hot forging wear out quickly due to their high temperature range of use, especially above 750°C, and the alloy of the part which is aggressive to the tooling.

[0007] Furthermore, due to successive forging operations on the tooling, certain parts of the insert reach, through cycling, a temperature exceeding 750°C which irreversibly damages the alloy that makes up the tooling.

[0008] However, the superalloys generally used in inserts, such as nickel-based alloys like 1TNCONEL® 718, have grain boundaries which, under such thermal stresses, undergo intergranular slippage. This results in an alteration of the material's mechanical properties at high temperatures. Consequently, the working shape of the insert gradually deteriorates with repeated use.

[0009] When the surface of a metal part is degraded, it is known to carry out a resurfacing operation carried out by adding metallic materials consisting of covering the altered surface with a new thickness of identical material.

[0010] However, cladding by adding metallic materials such as nickel-based superalloys like 1TNCONEL® 718 requires skilled personnel, and the high cost of welding rods results in prohibitive implementation costs. Additive cladding with metallic materials using welding rods generally requires the deposition of an underlayer. Furthermore, the interface zone between the substrate and the cladding material creates a zone of weakness, a thermally affected area, and a risk of delamination of the cladding material.

[0011] In addition, tooling inserts for die forging have extensive, thick hardfacing areas, and superalloys are sensitive materials, so the quality of the hardfacing is not very reproducible over time and weld defects cannot be avoided.

[0012] The welding process also results in a large thermally affected area and therefore a risk of decohesion of the weld from its support.

[0013] In order to guarantee their mechanical properties and the conformity of the parts they produce, these inserts are discarded when they are too damaged, and the insert must be completely replaced with a new one.

[0014] The cost of manufacturing a pair of upper and lower half-inserts is substantial. The availability of these new inserts is also very lengthy. Description of the invention

[0015] The present invention therefore aims to overcome the aforementioned disadvantages and to provide a quick and economical solution for repairing tooling inserts for forging by hot die forging.

[0016] A method for repairing a forging tool insert by die forging is therefore proposed, the insert comprising a portion to be repaired having an outer surface with a first geometric profile, the method comprising:

[0017] a step of removing the portion to be repaired from the rest of the insert and forming an attachment surface on the rest of the insert, the attachment surface comprising an outer surface formed by a central zone and a peripheral zone that gradually extends from the central zone to the outer surface of the rest of the insert; and

[0018] a reloading step by additive manufacturing by laser metal deposition on the attachment base for the formation of a new portion to replace the removed portion to be repaired.

[0019] The attachment base, and in particular the peripheral zone, forms a gradual base which guarantees the hold of the bead of solid material formed during the re-building, and makes possible such re-building by additive manufacturing by laser metal deposition.

[0020] The damaged insert is then repaired by a simple, reliable, fast and reproducible process.

[0021] Preferably, the central area of ​​the outer surface of the anchoring base has a second geometric profile identical to the first profile of the outer surface of the portion to be repaired and of smaller dimensions, the central area of ​​the outer surface of the anchoring base and the outer surface of the portion to be repaired being parallel.

[0022] Preferably, the peripheral area of ​​the outer surface of the attachment seat has a radius of curvature extending from the central area to the outer surface of the rest of the insert, the concave face of the radius of curvature being oriented towards the outside of the insert.

[0023] Preferably, the radius of curvature is greater than or equal to 8 mm.

[0024] Advantageously, the step of removing the portion to be repaired and forming the attachment base can be followed by a step of checking the dimensions of the attachment base.

[0025] Advantageously, the process may include a step of sizing the new portion, such as a machining step.

[0026] In one embodiment, the new portion and the attachment base are formed from a first identical material.

[0027] In another embodiment, the attachment base is formed by a first material and the new portion is formed by a second material of greater hardness than the first material.

[0028] In another embodiment, the new portion comprises a first face oriented towards the attachment seat and a second opposite face oriented towards the outside of the insert, the attachment seat being formed by a first material, and the cladding step by additive manufacturing by laser metal deposition being carried out from the first and a second material of greater hardness than the first material so that the first and second materials form a gradient between the first and second faces.

[0029] For example, the first and / or second material comprises a nickel-based alloy. Brief description of the drawings

[0030] The present invention will be better understood and other objects, advantages and features will become apparent from the following detailed description, including embodiments given by way of illustration only and made with reference to the accompanying drawings, presented as non-limiting examples, which may serve to complete the understanding of the invention and the explanation of its implementation and, where appropriate, contribute to its definition, on which:

[0031] [Fig.l] is a cross-sectional view of a damaged tooling insert for hot die forging.

[0032] [Fig.2] is a flowchart illustrating a method for repairing a tooling insert for hot die forging according to an embodiment of the invention.

[0033] [Fig.3] is a cross-sectional view of the insert illustrated in [Fig.1] from which a portion to be repaired has been removed and a mounting base formed according to an embodiment of the invention.

[0034] [Fig.4] is a cross-sectional view of the insert illustrated in [Fig.1] repaired according to a method of realization of the invention. Detailed description of at least one embodiment

[0035] Fig. 1 illustrates a damaged hot forging tooling insert 1 that needs to be repaired.

[0036] In the illustrated example, the insert 1 shown is a tooling insert intended for forming an aircraft turbine disk.

[0037] The illustrated insert 1 is circular and forms a solid disk extending around a central axis X. The insert 1 has first and second faces 1a and 1b opposite each other delimiting the thickness of the insert 1.

[0038] The first face la has an imprint E of the turbine disk to be formed.

[0039] Of course, the insert 1 is not limited to the formation of a turbine disk and can be used to form any other type of part, and is not limited to the aerospace field. The imprint E of the first face la of the insert will then be adapted to the shape of the part to be formed.

[0040] The illustrated insert 1 includes a damaged portion to be repaired 2. The portion 2 of the insert 1 to be repaired has an outer surface Si which extends over the first face la of the insert 1 and forms part of the impression E.

[0041] The outer surface Si of the portion to be repaired 2 has a first geometric profile and is extended by an outer surface S2 of the remainder of the first face la of the insert.

[0042] In the illustrated example, the outer surface Si of the portion to be repaired 2 has a cup-shaped profile.

[0043] Fig. 2 illustrates a method for repairing the tool insert 1 for forging by hot die forging.

[0044] With reference to [Fig.3], in a first step 100, the portion to be repaired 2 which is damaged is removed from the rest of the insert 1.

[0045] The first step 100 also includes the formation of a seat or mounting base 3 on the rest of the insert 1.

[0046] The attachment seat 3 which is formed on the first face la of the insert 1 when removing the portion to be repaired 2 comprises an outer surface S3 comprising a central zone 3 a and a peripheral zone 3b.

[0047] In the illustrated example, the attachment base 3 forms a bell shape.

[0048] The peripheral zone 3b of the outer surface S3 extends gradually from the central zone 3a to the outer surface S2 of the remainder of the first face la of the insert 1.

[0049] In other words, the peripheral area 3b of the outer surface S3 of the attachment seat 3 gradually extends from the central area 3a to an interface I formed between the outer surface Side the portion to be repaired 2 and the outer surface S2 of the remainder of the first face la of the insert 1.

[0050] In the illustrated example, the removal of the portion to be repaired 2 and the formation of the attachment seat 3 are carried out by machining.

[0051] Preferably, the attachment base 3 is formed so that the central area 3a of the outer surface S3 has a second geometric profile identical to the first profile of the outer surface Si of the portion to be repaired 2 removed, but of smaller dimensions.

[0052] The machining step for producing the second profile of the outer surface S3 of the central zone 3a of the attachment seat 3 is carried out parallel to the first profile of the portion to be repaired 2. In this way, before removal of the portion to be repaired 2, and as can be seen in [Fig.1], the central zone 3a of the outer surface S3 of the attachment seat 3 and the outer surface Side of the portion to be repaired 2 are parallel.

[0053] The portion to be repaired 2 removed can then be minimized to carry out a minimum thickness build-up and save the material needed for the build-up.

[0054] In the illustrated example, the first step 100 of removing the portion to be repaired 2 and forming the anchoring base 3 is advantageously followed by a second step 200 of checking the dimensions of the anchoring base 3 formed in order to ensure the conformity of the anchoring base 3, to be able to quantify the material added during the reconstruction of the portion to be repaired 2 and to achieve a saving of material.

[0055] With reference to [Fig.4], in a third step 300, the build-up is carried out by additive manufacturing by laser metal deposition on the mounting base of a new portion 4 in replacement of the portion to be repaired 2 removed.

[0056] Additive manufacturing by laser metal deposition refers to a cladding process commonly called additive manufacturing by powder spraying or "LMD process", an acronym for the Anglo-Saxon terms "Laser Metal Deposition", and which allows the formation of a part or a portion of a part by successive deposits of metallic material melted by a laser.

[0057] A laser beam is used to create a molten pool on a substrate, here formed by the adhesion layer 3, onto which a powder of material is deposited. The powder then passes through the laser beam and melts into the substrate, forming, after solidification, a bead of solid material that adheres to the substrate by fusion. As the metal is depositioned by laser, several beads bonded during solidification are superimposed on the first bead until the desired portion of the part is obtained through successive additions of layers.

[0058] Laser metal deposition offers the following advantages: high deposition speed, a controllable atmosphere, use on large components, the formation of complex shapes, controlled material supply, and reproducibility. Furthermore, since the deposited layers are bonded to the substrate by fusion, there is no risk of decohesion.

[0059] In addition, a wide range of materials can be used for the reloading and substrate.

[0060] The new portion 4 obtained and the insert 1 form a monobloc structure.

[0061] The central zone 3a and the peripheral zone 3b of the attachment base 3 form A base for laser metal deposition cladding. The presence of the gripping base promotes adhesion of the bead of solid material formed during the laser metal deposition process.

[0062] In particular, the peripheral zone 3b of the attachment seat 3 forms a gradual seat for the material cord.

[0063] Preferably, the peripheral area 3b of the outer surface S3 of the attachment seat 3 formed in the first step 100 has a radius of curvature whose concave face is oriented towards the outside of the insert 1.

[0064] The radius of curvature extends from the central area 3a to the outer surface S2 of the remainder of the first face of the insert 1.

[0065] In other words, the radius of curvature of the peripheral zone 3b extends from the central zone 3a to the interface I formed between the outer surface Side the portion to be repaired 2 and the outer surface S2 of the remainder of the first face la of the insert 1.

[0066] Such a radius of curvature forms a very gradual base favorable to the gripping of the bead of solid material formed as the reloading progresses.

[0067] Preferably, the radius of curvature is greater than or equal to 8 mm. Such a range of values ​​optimizes the adhesion of the solid material bead.

[0068] Advantageously, the repair process may include a fourth step 400 of bringing the new portion 4 to the correct dimensions, for example by machining.

[0069] Even more advantageously, the repair process may include a fifth step 500 of heat and surface treatment aimed at treating the outer surface S4 of the new portion 4 formed.

[0070] In one embodiment, the new portion 4 and the rest of the insert 1, including the attachment base 3 on which the new portion 4 is formed, can be formed from a first identical material.

[0071] In another embodiment, the insert 1, with the exception of the new portion 4, and in particular the attachment seat 3, can be formed from a first material and the new portion 4 is formed from a second material of greater hardness than the first material.

[0072] The new portion 4 comprises a first face oriented towards the attachment base 3 and a second opposite face oriented towards the outside of the insert 1.

[0073] In another embodiment, the attachment base 3 can be formed from a first material. The cladding step 300, using additive manufacturing by laser metal deposition, can then be carried out from the first and a second material with a greater hardness than the first material, such that the first and second materials form a gradient between the first and second faces of the new portion 4.

[0074] According to one example, the first material may be predominant on the first face oriented towards the attachment base 3 and the second material may be predominant on the opposite second face oriented towards the outside of the insert 1

[0075] According to an alternative, the second material may be predominant towards the first face oriented towards the attachment seat 3 and the first material may be predominant towards the second opposite face oriented towards the outside of the insert 1.

[0076] For example, the first and / or second materials comprise a nickel-based alloy.

[0077] The nickel-based alloy of formula NiCrl9Fel8Nb is, for example, the material known under the brand name Inconel® 718.

[0078] For example, the first material may be Inconel® 718 and the second material may be IN-100 Alloy® with a higher hardness than Inconel® 718.

Claims

Demands

1. A method for repairing a forging tool insert by die forging, the insert (1) comprising a portion to be repaired (2) having an outer surface (Si) having a first geometric profile, the method comprising: a step (100) of removing the portion to be repaired (2) from the rest of the insert and of forming a mounting surface (3) on the rest of the insert, the mounting surface (3) comprising an outer surface (S3) formed by a central zone (3a) and a peripheral zone (3b) which gradually extends from the central zone (3a) to an outer surface (S2) of the rest of the insert; and a step (300) of adding metal to the mounting surface (3) by laser metal deposition to form a new portion (4) in replacement of the removed portion to be repaired (2).

2. A method according to claim 1, wherein the central zone (3a) of the outer surface (S3) of the attachment base (3) has a second geometric profile identical to the first profile of the outer surface (Si) of the portion to be repaired (2) and of smaller dimensions, the central zone (3a) of the outer surface (S3) of the attachment base (3) and the outer surface (Si) of the portion to be repaired (2) being parallel.

3. Method according to claim 1 or 2, wherein the peripheral area of ​​the outer surface (S3) of the attachment seat (3) has a radius of curvature extending from the central area (3a) to the outer surface (S2) of the rest of the insert, the concave face of the radius of curvature being oriented towards the outside of the insert (1).

4. Method according to claim 3, wherein the radius of curvature is greater than or equal to 8 mm.

5. A method according to any one of the preceding claims, wherein the step (100) of removing the portion to be repaired (2) and of forming the anchoring base is followed by a step (200) of checking the dimensions of the anchoring base (3).

6. A method according to any one of the preceding claims, comprising a step (400) of sizing the new portion (4) such as a machining step.

7. A method according to any one of the preceding claims, wherein the new portion (4) and the attachment base (3) are formed from a first identical material.

8. A method according to any one of claims 1 to 6, wherein the attachment seat (3) is formed from a first material and the new portion (4) is formed from a second material of greater hardness than the first material.

9. A method according to claim 8, wherein the new portion (4) comprises a first face oriented towards the attachment seat and a second opposite face oriented towards the outside of the insert (1), the attachment seat (3) being formed by a first material, and the step (300) of cladding by additive manufacturing by laser metal deposition being carried out from the first and a second material of greater hardness than the first material such that the first and second materials form a gradient between the first and second faces.

10. A method according to any one of claims 7 to 9, wherein the first and / or second materials comprise a nickel-based alloy.

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