Method for repairing a tool insert for forging by stamping

Abstract

The invention relates to a method for repairing a tool insert (1) for forging by stamping, 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 an attachment seat (3) on the rest of the insert, the attachment seat (3) comprising an outer surface (S3) formed by a central zone (3a) and a peripheral zone (3b) which extends gradually from the central zone (3a) to the outer surface (S2) of the rest of the insert; and a step of hardfacing by additive manufacturing by laser metal deposition on the attachment seat (3) for the removed portion to be repaired.

Description

[0001] DESCRIPTION

[0002] TITLE: Method for repairing a forging tool insert by die forging

[0003] technical field

[0004] 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.

[0005] More specifically, the invention relates to a method for repairing a forging tool insert by die forging.

[0006] Previous techniques

[0007] Die forging involves forming a part by plastically deforming a blank heated to an appropriate temperature. The blanks are generally made of non-ferrous alloys such as aluminum, copper, titanium, nickel, etc.

[0008] Die forging is a forging operation performed using tooling that includes 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.

[0009] In the field of aeronautical turbomachinery, this forging technique is used to manufacture, among other things, turbine discs.

[0010] Inserts used for hot die forging wear out quickly due to their high-temperature operating range, especially above 750°C, and the workpiece alloy being aggressive to tooling.

[0011] Furthermore, due to successive forging operations on the tooling, certain parts of the insert reach temperatures exceeding 750°C through repeated cycling, irreversibly damaging the alloy from which the tooling is made. However, the superalloys typically used in inserts, such as nickel-based alloys like INCONEL® 718, possess grain boundaries that, under such thermal stresses, undergo intergranular slippage. This alters the material's mechanical properties at high temperatures, resulting in a gradual creep of the insert's working shape with repeated use.

[0012] 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.

[0013] However, metal cladding using additive metallic materials such as nickel-based superalloys like INCONEL® 718 requires skilled personnel, and the high cost of welding rods results in prohibitive implementation costs. Additive cladding with welding rods generally requires the deposition of an underlayer. Furthermore, the interface 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.

[0014] Furthermore, die-forging tooling inserts 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.

[0015] The welding process also results in a large heat-affected area and therefore a risk of the weld detaching from its support.

[0016] 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. The cost of producing a pair of upper and lower insert halves is substantial. The availability of these new inserts is also very slow.

[0017] Description of the invention

[0018] 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.

[0019] A repair process for a forging tool insert by die forging is therefore proposed, the insert comprising a portion to be repaired having an outer surface having a first geometric profile, the process comprising: a step of removing the portion to be repaired from the rest of the insert and of forming a mounting surface on the rest of the insert, the mounting surface comprising an outer surface formed by a central zone and a peripheral zone which gradually extends from the central zone to the outer surface of the rest of the insert; and a step of build-up by additive manufacturing by laser metal deposition on the mounting surface to form a new portion to replace the removed portion to be repaired.

[0020] The attachment base, and in particular the peripheral area, forms a gradual base which guarantees the stability of the bead of solid material formed during the re-building, and makes possible such re-building by additive manufacturing by laser metal deposition.

[0021] The damaged insert is then repaired by a simple, reliable, fast and reproducible process.

[0022] 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.

[0023] 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, with the concave face of the radius of curvature oriented towards the outside of the insert.

[0024] Preferably, the radius of curvature is greater than or equal to 8 mm.

[0025] Advantageously, the step of removing the portion to be repaired and forming the anchoring base can be followed by a step of checking the dimensions of the anchoring base.

[0026] Advantageously, the process may include a step of sizing the new portion, such as a machining step.

[0027] In one embodiment, the new portion and the attachment base are formed from an identical first material.

[0028] In another embodiment, the attachment base is formed from a first material and the new portion is formed from a second material of greater hardness than the first material.

[0029] 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.

[0030] For example, the first and / or second material contains a nickel-based alloy.

[0031] Brief description of the drawings

[0032] The present invention will be better understood and other objects, advantages and features will become apparent from the detailed description that follows, including embodiments given purely by way of illustration 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 realization and, where appropriate, contribute to its definition, on which: [Fig 1] is a cross-sectional view of a damaged insert of hot forging tooling.

[0033] [Fig 2] is a flowchart illustrating a method for repairing a tooling insert for hot die forging according to an embodiment of the invention.

[0034] [Fig 3] is a cross-sectional view of the insert illustrated in figure 1, a portion of which has been removed to be repaired and a mounting base formed according to an embodiment of the invention.

[0035] [Fig 4] is a cross-sectional view of the insert illustrated in figure 1 repaired according to an embodiment of the invention.

[0036] Detailed description of at least one embodiment

[0037] Figure 1 illustrates a damaged hot forging tooling insert 1 that needs to be repaired.

[0038] In the illustrated example, insert 1 shown is a tooling insert intended for forming an aircraft turbine disk.

[0039] 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.

[0040] The first face has an imprint E of the turbine disk to be formed.

[0041] Of course, insert 1 is not limited to forming a turbine disk and can be used to form any other type of part, and is not limited to the aerospace sector. The imprint E of the first face la of the insert will then be adapted to the shape of the part to be formed.

[0042] The illustrated insert 1 includes a damaged portion to be repaired. Portion 2 of insert 1 to be repaired has an exterior surface

[0043] 51 which extends over the first face of the insert 1 and forms part of the impression E.

[0044] The outer surface S i of the portion to be repaired 2 has a first geometric profile and is extended by an outer surface

[0045] 52 of the remainder of the first face of the insert. In the illustrated example, the outer surface S i of the portion to be repaired 2 has a cup-shaped profile.

[0046] Figure 2 illustrates a method for repairing insert 1 of forging tooling by hot die forging.

[0047] With reference to figure 3, in a first step 100, the portion to be repaired 2 which is damaged is removed from the rest of the insert 1.

[0048] The first step 100 also includes the formation of a seat or mounting base 3 on the rest of the insert 1.

[0049] The attachment seat 3 which is formed on the first face of the insert 1 when the portion to be repaired 2 is removed comprises an outer surface S3 comprising a central zone 3a and a peripheral zone 3b.

[0050] In the illustrated example, the hanging base 3 forms a bell shape.

[0051] The peripheral zone 3b of the outer surface S3 gradually extends from the central zone 3a to the outer surface S2 of the remainder of the first face la of the insert 1.

[0052] In other words, the peripheral zone 3b of the outer surface S3 of the attachment seat 3 gradually extends from the central zone 3a to an interface I formed between the outer surface S i of the portion to be repaired 2 and the outer surface S2 of the remainder of the first face la of the insert 1.

[0053] 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.

[0054] 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 S i of the portion to be repaired 2 removed, but of smaller dimensions.

[0055] The machining step for the realization of 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 figure 1, the central zone 3a of the outer surface S3 of the attachment seat 3 and the outer surface Si of the portion to be repaired 2 are parallel.

[0056] The portion to be repaired 2 removed can then be minimized to perform a minimum thickness build-up and save the material needed for the build-up.

[0057] 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.

[0058] With reference to figure 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.

[0059] Additive manufacturing by laser metal deposition refers to a build-up process commonly called additive manufacturing by powder projection or "LMD process", an acronym for the Anglo-Saxon terms "Laser Metal Deposition", which allows the formation of a part or a portion of a part by successive deposits of metallic material melted by a laser.

[0060] A laser beam is used to create a molten pool on a substrate, in this case 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.

[0061] Laser metal deposition offers several advantages: high deposition speed, a controllable atmosphere, the ability to handle large components, the creation of complex shapes, controlled material delivery, and reproducibility. Furthermore, because the deposited layers are fused to the substrate, there is no risk of delamination.

[0062] In addition, a wide range of materials can be used for resurfacing and substrate.

[0063] The new portion 4 obtained and the insert 1 form a monobloc structure.

[0064] The central zone 3a and the peripheral zone 3b of the adhesion platform 3 form a base for laser metal deposition. The presence of the adhesion platform promotes the adhesion of the bead of solid material formed during the laser metal deposition process.

[0065] In particular, the peripheral zone 3b of the hooking seat 3 forms a gradual seat for the material cord.

[0066] Preferably, the peripheral zone 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.

[0067] 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.

[0068] 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 S i of the portion to be repaired 2 and the outer surface S2 of the remainder of the first face la of the insert 1.

[0069] Such a radius of curvature forms a very gradual base favorable to the adhesion of the bead of solid material formed during the reloading process.

[0070] 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.

[0071] Advantageously, the repair process may include a fourth step 400 of dimensionally shaping the new portion 4, for example by machining. Even more advantageously, the repair process may include a fifth step 500 of heat and surface treatment aimed at treating the external surface S4 of the newly formed portion 4.

[0072] In one embodiment, the new portion 4 and the remainder 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.

[0073] In another embodiment, the insert 1, with the exception of the new portion 4, and in particular the attachment base 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.

[0074] 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.

[0075] In another embodiment, the attachment base 3 can be formed from a first material. The 300 step of additive manufacturing by laser metal deposition can then be carried out using 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 of the new portion 4.

[0076] For example, the first material may be predominant on the first face oriented towards the mounting base 3, and the second material may be predominant on the opposite second face oriented towards the outside of the insert 1.

[0077] According to an alternative, the second material can be predominant towards the first face oriented towards the attachment base 3 and the first material can be predominant towards the second opposite face oriented towards the outside of the insert 1.

[0078] For example, the first and / or second materials contain a nickel-based alloy.

[0079] The nickel-based alloy with the formula NiCrl 9Fe l 8Nb is, for example, the material known under the brand name Inconel® 718. 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 (S i) 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 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, the central zone (3a) of the outer surface (S3) of the mounting surface (3) having a second geometric profile identical to the first profile of the outer surface (S i) of the portion to be repaired (2) and of smaller dimensions,the central zone (3a) of the outer surface (S3) of the anchoring base (3) and the outer surface (S i) of the portion to be repaired (2) being parallel; and a step (300) of additive manufacturing build-up by laser metal deposition on the anchoring base (3) for the formation of a new portion (4) to replace the removed portion to be repaired (2).

2. Method according to claim 1, 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).

3. Method according to claim 2, wherein the radius of curvature is greater than or equal to 8 mm.

4. 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).

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

6. 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.

7. A method according to any one of claims 1 to 5, 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.

8. Method according to claim 7, 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.

9. A method according to any one of claims 6 to 8, wherein the first and / or second materials comprise a nickel-based alloy.

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