Tool for reducing the deformation of steel parts during the quenching thereof

Abstract

The invention relates to an anti-deformation quenching tool (1) for a part (11) with at least one hollow frustoconical or cylindrical portion (9) comprising a side wall (21) terminated at each of its ends (22) by an annular end edge (8). The tool comprises at least two anti-deformation tools (2) made of steel, each intended to be mounted on one of the ends of the side wall, and each comprising: - a flat annular body (3), comprising a planar annular bearing face (7), provided to be placed against and to cover the corresponding annular end edge; and - a cylindrical retaining rim (14), bordering the planar annular bearing face internally or externally and extending perpendicularly thereto away from the flat annular body, which is intended to bear against an inner face (26) or an outer face (27), respectively, of the side wall.

Description

DESCRIPTION Tooling that reduces the deformation of cylindrical or frustoconical steel parts during their hardening TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a tool that makes it possible to reduce deformation by cone-forming the ends of hollow cylindrical or truncated conical portions of steel parts subjected to gas quenching treatment.

[0002] The invention also relates to a method of reducing deformations by cone-forming the ends of hollow cylindrical or frustoconical portions of steel parts during gas quenching.

[0003] The invention finds applications, for example, in the field of gear and bearing manufacturing, particularly in the field of aeronautics and especially in that of aircraft turbomachinery. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0004] In many technological fields, and particularly in the aeronautical sector, steel parts with cylindrical or frustoconical shapes, or with one or more cylindrical or frustoconical sections, are frequently used. Examples include gear components such as cylindrical or bevel gears, or bearing components such as plain bearings or roller bearings.

[0005] After machining, these parts often undergo a quenching heat treatment to give the steel a martensitic or bainitic structure, which increases its hardness. This heat treatment can advantageously be preceded by a case hardening treatment during which the surface layer of the steel part is enriched with carbon.

[0006] The quenching treatment consists of gradually heating the part in a furnace until a target temperature is reached and maintained for an appropriate duration, then cooling it very rapidly to cause the desired martensitic or bainitic transformation, without the formation of other phases or the precipitation of carbides.

[0007] To achieve this, different forced cooling methods can be used depending on the nature of the alloy composing the part.

[0008] One method involves circulating a cooling gas (such as nitrogen, argon, hydrogen, or helium) under pressure in the furnace containing the part. Outside the treatment chamber, the gas flow is agitated by a turbine and passes through a heat exchanger that cools it before it is reintroduced into the furnace.

[0009] A quenching heat treatment of this type is generally called "gas quenching" or "gas quenching" or "gas quenching". The invention relates specifically to this type of quenching.

[0010] Such rapid cooling by gas flow creates thermal gradients within the part to be cooled, on the one hand between the surface and the core of the part, but also between other parts of the part (top / bottom, front / back...) depending on the geometry of the part and the furnace, as well as the path of the gas in the furnace.

[0011] These temperature gradients generate significant stresses within the part, particularly between areas that have already been transformed and those that are more easily deformed. This results in distortions and deformations of the part, to varying degrees depending on its geometry.

[0012] In particular, when the part includes one or more hollow cylindrical or truncated conical sections, a deformation called "coning" of the ends of these sections is frequently observed, which tend to contract inwards during cooling.

[0013] This deformation is particularly problematic, as it requires complex, lengthy and expensive rectification processes to give the part its final geometry.

[0014] After hardening, the part must be machined to remove the deformed areas. The initial part must therefore be made thicker than the desired final part in order to achieve the required dimensions after grinding, and a significant amount of material is lost as grinding chips. Furthermore, when the deformation is too extensive, grinding is impossible and the entire part is discarded.

[0015] This deformation is even more problematic when the part has undergone prior case hardening of its surface layer. Indeed, it is then necessary to ensure that the case hardening depth remains sufficient throughout the entire part, despite the grinding. As a precaution, a deeper case hardening of the original part must be performed, which considerably lengthens the case hardening operation and increases its cost.

[0016] In addition to these industrial manufacturing difficulties, these deformations often lead to poor homogeneity of part properties, which are no longer identical everywhere after grinding, which can be problematic for the subsequent use of the part.

[0017] In prior art, attempts were made to limit these deformations by trying to control the quenching cooling conditions, for example, by attempting to homogenize the temperature inside the furnace during cooling. However, these methods are very complex to implement and cannot be applied industrially. No satisfactory solution has yet been proposed.

[0018] There is therefore a need, currently unmet, for a device and / or process that is both effective, economical and easy to implement, which would limit deformations by cone-forming the ends of hollow cylindrical or truncated conical portions of steel parts during gas quenching treatment. SUMMARY OF THE INVENTION

[0019] The invention aims to address this need.

[0020] For this purpose, a first aspect of the invention teaches an anti-deformation quenching tool for a part with at least one hollow, cylindrical or frustoconical portion.

[0021] This hardening tooling comprises at least two anti-deformation steel tools, each including: a flat annular body, which has a flat annular bearing face extending between an inner perimeter edge and an outer perimeter edge; and a cylindrical retaining rim, perpendicular to the flat annular support face, which starts from said inner or outer perimeter edge and moves away from the flat annular body.

[0022] In this application, the term "cylindrical" will be understood as referring to a right cylinder whose cross-section is not necessarily circular, but can take the form of any closed plane curve. Although preferably circular, this cross-section can also be, for example, oval, square, rectangular, hexagonal, etc.

[0023] Similarly, an annular element is not necessarily circular, but has a shape corresponding to the cylindrical part it is intended to equip, its section being able to be defined as a surface between two concentric closed plane curves (which constitute its perimeter edges), this surface surrounding a central opening.

[0024] This hardening tooling is advantageously suited to protect from deformation a cylindrical or truncated conical portion having a lateral wall which extends between a first and a second end and terminates with an annular end edge at each of its ends.

[0025] Each of the tooling's anti-deformation tools is intended to be mounted on one end of this side wall during gas cooling, with its flat annular bearing face placed against and covering the annular end edge of said end and its cylindrical retaining rim bearing against an inner or outer face respectively of said side wall.

[0026] Thus during cooling, the flat annular body, which forms a metal ring or washer resting against the annular edge of the free end of the cylindrical or truncated conical portion, slows down the cooling at this end, without opposing that of the inner and outer faces of the side wall.

[0027] Indeed, by covering the end annular edge, the flat annular body increases thermal resistance at this level and forms a barrier that prevents the cooling gas from reaching the end annular edge.

[0028] Because it is annular, the flat annular body does not prevent the cooling gas from reaching both faces (inner and outer) of the cylindrical wall and does not oppose cooling at this level.

[0029] Furthermore, the cylindrical retaining rim is merely a simple rim, serving only to position and secure the tool on the corresponding cylindrical section. It is therefore of low height and unlikely to cover a significant portion of the cylindrical wall. Consequently, it has little influence on cooling.

[0030] The flat annular body thus reduces the heat flow exiting the ends of the cylindrical or frustoconical portion, leaving primarily that which escapes at the lateral wall. This prevents faster cooling at the ends of the cylindrical or frustoconical portion, where heat could escape both laterally and in the direction of the end, than at the lateral wall where it can only escape laterally.

[0031] Heat dissipation is thus more homogeneous over the entire cylindrical or truncated conical portion, which limits stress at this level and reduces the appearance of distortions, particularly "cone-forming" deformations.

[0032] Advantageously, the flat annular body can be made of austenitic stainless steel, for example type 304L, because this steel has good thermal resistance.

[0033] The thermal resistance of the flat annular body also depends on its thickness, which will be adapted according to the mass of the part to be protected. Advantageously, this thickness is preferably between 1 and 15 mm, which makes it possible to obtain good thermal resistance without significantly increasing the mass to be immersed in the furnace.

[0034] Advantageously, according to a second embodiment, at least one of the tools of the hardening tooling may further comprise: a second flat annular body, coaxial and of greater diameter than said flat annular body, which comprises a second flat annular support face extending between a second inner perimeter edge and a second outer perimeter edge; a second cylindrical retaining rim, perpendicular to the second flat annular support face, which starts from said second inner or outer perimeter rim and moves away from the second flat annular body; and at least one inclined connecting arm, which connects the flat annular body with the second flat annular body.

[0035] This hardening tool is suitable for protecting from deformation a steel part which includes a second hollow cylindrical or truncated conical portion, coaxial and of a diameter greater than the hollow cylindrical or truncated conical portion already described, comprising a second lateral wall which extends between a first end and a second end and which terminates with an annular end edge at each of its ends.

[0036] It can advantageously protect the ends of the first and second cylindrical or frustoconical portions simultaneously during gas cooling. Each of the anti-deformation tools can indeed be mounted on one side of the workpiece with its flat annular support face placed against and covering the annular end edge of the first cylindrical or frustoconical portion and its second flat annular support face placed against and covering the annular end edge of the second cylindrical or frustoconical portion, the cylindrical retaining edges serving to ensure the positioning and retention of the tool on the corresponding cylindrical portions.

[0037] The angled connecting arm(s) advantageously link the two flat annular bodies to create a simple and practical one-piece tool that can be installed in a single step. Furthermore, the second flat annular support face can thus be held against the corresponding end annular edge, even if it is the tool mounted on the lower end of the workpiece.

[0038] Since the two annular bodies are linked by one or more inclined arms and not by a continuous wall, the flow of cooling gas can circulate between the different arms and between the arms and the wall of the cylindrical or frustoconical portion, the cooling of this wall is therefore not impacted by their presence.

[0039] Advantageously, in this case, the tool may comprise at least two inclined connecting arms, and preferably two to eight inclined connecting arms, distributed radially around the flat annular body with a constant angular spacing. The second flat annular body is thus perfectly supported along its entire circumference, in a stable and balanced manner.

[0040] Advantageously, at least one of the tools may further comprise an annular layer of solid thermal insulation on at least one of its flat annular support faces.

[0041] This insulating layer advantageously increases the thermal resistance of the tool, without increasing the thickness of the flat annular body and thus without increasing the mass of steel to be hardened in the furnace.

[0042] Furthermore, the presence of this insulation advantageously compensates for the gaps existing between the part to be protected and the anti-deformation tool, in order to prevent the circulation of the cooling gas between them while allowing their differential expansion.

[0043] The solid thermal insulation used is preferably a ceramic material, for example alumina or zirconia, because this type of material has good thermal resistance properties and retains them over the entire temperature range classically used during a quenching heat treatment.

[0032] The thermal resistance of the insulation layer also depends on its thickness. Advantageously, this thickness is preferably between 0.5 and 3 mm, and for example substantially equal to 1 or 1.2 mm, which gives it a satisfactory thermal resistance.

[0044] Advantageously, said annular layer can be formed from a plate, a set of juxtaposed blocks, a strip or a cord wound for example in a serpentine fashion.

[0045] A second aspect of the invention relates to a quenching assembly comprising: a steel part, with at least one hollow, cylindrical or frustoconical portion, this hollow, cylindrical or frustoconical portion having a lateral wall extending between a first end and a second end and terminates with an annular end edge at each of its ends; and a hardening tool according to any one of the preceding claims, comprising an anti-deformation tool mounted on each end of the side wall, with its flat annular bearing face disposed against and covering the annular end edge of the end on which the tool is mounted and with its cylindrical retaining rim bearing against an inner or outer face respectively of the side wall.

[0046] This hardening assembly is formed by equipping a steel part with a hollow cylindrical or truncated conical portion of a hardening tool as described previously, giving it all the advantages previously described.

[0047] Advantageously, the flat annular support face can have dimensions that correspond substantially to those of the end annular edge it covers. It can thus advantageously cover the entire annular edge, preventing any contact between the cooling gas and this annular edge, but without extending too far beyond it so as not to disrupt the gas flow towards the side wall, nor excessively increase the mass of steel to be quenched in the furnace.

[0048] In this request, we will define a dimension that is substantially equivalent to another, as being equal to it to plus or minus 5%.

[0049] Advantageously, this quenching assembly can be such that the quenching tooling corresponds to the second embodiment, and that: the steel part further comprises a second hollow portion, cylindrical or frustoconical, coaxial and of a diameter greater than said hollow portion, cylindrical or frustoconical, comprising a second lateral wall extending between a first end and a second end and terminating in an annular end edge at each of its extremities; and the second flat annular bearing face is disposed against and covers one of the annular end edges of the second lateral wall; and the second cylindrical retaining rim rests against an inner or outer face respectively of the second lateral wall.

[0050] Advantageously, the steel part can be a gear part, preferably a cylindrical or conical pinion; or a bearing part, preferably a plain bearing or a rolling ring.

[0051] A third aspect of the invention relates to a method for limiting the deformation of the ends of a hollow, cylindrical or frustoconical portion of a steel part subjected to a quenching heat treatment.

[0052] This process comprises the following steps: supplying a steel part, with at least one hollow, cylindrical or frustoconical portion, this hollow, cylindrical or frustoconical portion, having a side wall which extends between a first end and a second end and terminates with an annular end edge at each of its ends, supplying a quenching tool as described above, forming a quenching assembly by placing an anti-deformation tool of the quenching tool on each of the ends of the side wall, with its flat annular bearing face disposed against and covering the annular end edge of the end on which the tool is mounted and with its cylindrical retaining rim bearing against an inner or outer face respectively of the side wall, subjecting the quenching assembly to a gas quenching heat treatment.

[0053] This process limits deformation by conizing the cylindrical or truncated conical parts of steel pieces during their quenching.

[0054] As a result, rework operations in grinding are less frequent and simpler to perform. The amount of grinding chips and the scrap rate are reduced. In addition, the case hardening depth can also be reduced.

[0055] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0056] The figures are presented for illustrative purposes only and are in no way limiting to the invention.

[0057] [Fig. 1] is a perspective view of a first example of tooling according to the invention.

[0058] [Fig. 2], [Fig. 3] and [Fig. 4] are perspective views of three variants of one of the tools in this first example of tooling.

[0059] [Fig. 5], [Fig. 6] and [Fig. 7] are axial section views of three variants of this first example of tooling ([Fig. 5] corresponding to the variant of [Fig. 1]) placed on a cylindrical part to be protected from deformation during quenching.

[0060] [Fig. 8] is an axial cross-sectional view of a second example of tooling according to the invention, placed on a frustoconical part to be protected from deformation during quenching.

[0061] [Fig. 9], [Fig. 10] and [Fig. 11] are views, respectively in exploded perspective, perspective and axial section, of a third example of tooling according to the invention placed on a part comprising two cylindrical parts to be protected from deformation during quenching.

[0062] [Fig. 12] is an axial cross-sectional view of a fourth example of tooling according to the invention, placed on another part comprising two cylindrical parts to be protected from deformation during quenching. DETAILED DESCRIPTION

[0063] Unless otherwise specified, the same element appearing on different figures has a unique reference.

[0064] In this application, the term "gas quenching" refers to a quenching heat treatment during which the part is cooled by a gas stream.

[0065] The "axis" of annular parts, especially flat annular bodies, is the axis perpendicular to these annular elements that passes through their center.

[0066] The "axial" direction corresponds to a direction parallel to this axis, and a radial direction is a direction perpendicular and intersecting this axis.

[0067] Unless otherwise specified, the adjectives "interior" and "exterior" are used in this application with reference to a radial direction such that the inner part of an element is, along a radial direction, closer to the axis than the outer part of the same element.

[0068] By convention in this application, the terms "top", "bottom", "upper", "lower" will be defined according to the orientation adopted by the elements on the different figures, it being understood that this orientation will not necessarily be retained in use.

[0069] Figure 1 shows a first example of a hardening tool 1 according to the invention. This tool 1 comprises two anti-deformation tools 2 with opposite orientations, which are positioned one above the other. In this embodiment, these two tools 2 are identical, but this is obviously not always the case.

[0070] Each of these tools 2 has a flat annular body 3 with axis X, which includes two flat annular faces 4, an inner cylindrical face 5 and an outer cylindrical face 6.

[0071] In the example shown, the flat annular body 3 is circular and has an inner radius n and an outer radius r e .

[0072] As can be seen in figures 3 to 7, one of these flat annular faces 4, called the flat annular support face 7, is intended to be placed against the end annular edge 8 of a cylindrical portion 9 or truncated cone 10, here with a circular cross-section, of a steel part 11 to be protected from deformation.

[0073] This flat annular support face 7 is delimited by an inner perimeter edge 12 and an outer perimeter edge 13, which in this case are circular edges.

[0074] Each of these tools 2 also includes a cylindrical retaining rim 14, which borders the flat annular support face 7 internally or externally depending on the variants, originating respectively from the inner perimeter edge 12 or the outer perimeter edge 13.

[0075] All possible combinations are conceivable for the arrangement of the cylindrical retaining rims 14 of the two tools 2 of the hardening tooling 1.

[0076] Thus for example, in figures 1 to 4 and 7, the cylindrical retaining rim 14 starts from the inner perimeter edge 12 and borders internally the flat annular support face 7 on each of the two tools 2 of the hardening tooling 1.

[0077] On the contrary, in figure 5, this cylindrical retaining rim 14 starts from the outer perimeter edge 13 and borders externally the flat annular support face 7 on each of the two tools 2 of the hardening tooling 1.

[0078] Alternatively, in Figure 6, the cylindrical retaining rim 14 starts from the inner perimeter edge 12 and borders internally the flat annular support face 7 of one of the tools 2 (the upper tool 15 in the example shown), while it starts from the outer perimeter edge 13 and borders externally the flat annular support face 7 of the other tool 2 (the lower tool 16 in the example shown).

[0079] The arrangement chosen will preferably be selected by the person in the trade according to the characteristics of the area in relation to the steel part 11 to be equipped by this tool 2, so that for example this cylindrical retaining rim 14 is in contact with a portion of the smooth wall of the steel part 11 and does not damage a gear toothing potentially present in this area.

[0080] As can be seen in figures 2 to 4, one or more of the tools 2 may include an annular layer 17 of a solid thermal insulator on their flat annular bearing face 7.

[0081] This annular layer 17 can have different shapes. It can be, for example, a single-piece plate 18 with an annular shape as in Figure 2, or a juxtaposition of distinct elements such as patches, blocks 19 or juxtaposed insulating sectors as in Figure 3, or even a strip or cord 20 wound in a spiral so as to cover the flat annular support face 7 as in Figure 4. In this last case, the cylindrical retaining rim facilitates the making of this winding.

[0082] The annular layer 17 is attached to the flat annular support face 7 and can preferably be retained there in any suitable way, for example by wedging, gluing or with suitable ties.

[0083] As illustrated in figures 5 to 8, this hardening tool 1 is intended to be placed on a steel part 11 to be protected.

[0084] The part 11 includes at least one cylindrical portion 9 (figures 5 to 7) or one hollow frustoconical portion 10 (figure 8), having a lateral wall 21 which extends between two ends 22: a first end 23, for example upper, and a second end 24, for example lower.

[0085] The side wall 21 delimits a hollow interior volume 25 open at its ends 22. It has an interior face 26 and an exterior face 27 and terminates with an annular edge 8 at each of its ends 22.

[0086] To protect part 11 from deformation, a tool 2 of tooling 1 is mounted on each end 22, part 11 equipped with tools 2 constituting a quenching assembly 28.

[0087] For this purpose and as can be seen in figures 5 to 8, the flat annular support face 7 of each of the tools 2 is placed against the annular end edge 8 of the end 22 concerned, which it covers entirely.

[0088] When the tool 2 has an annular layer 17 of thermal insulation, this is interposed between the flat annular support face 7 and the annular end edge 8 as in figures 6 to 8.

[0089] In addition, the cylindrical retaining rim 14 is engaged with the end 22 of the side wall 21 of the part 11, in order to ensure correct positioning of the tool 2 and to retain it on the cylindrical portion 9 or conical portion 10 of the part 11. For this purpose, the cylindrical retaining rim 14 bears against the inner face 26 or against the outer face 27 of the side wall 21 depending on whether it borders the flat annular support face internally (figures 5, 7 and 8) or externally (figures 6 and 7).

[0090] The two tools 2 of the tooling 1 can be identical, particularly in the case of a cylindrical part 11 (figures 5 and 6), or different from each other: either because their cylindrical retaining rim 14 is not arranged in the same way (figure 7), because only one of them has an annular layer 17 of thermal insulation, because they are of different diameter for a truncated conical part 11 (figure 8), or because they are of different models (figure 12).

[0091] In some cases, part 11 may have several cylindrical portions 9 or truncated conical portions 10 to be protected. The tools 2 then have a more complex shape.

[0092] An example of such a part 11 is shown in Figures 9 to 11. It is a gear part 29 with two concentric cylindrical pinions 30 and 31, with a circular cross-section and straight teeth 32. These two pinions 30 and 31 constitute respectively the first cylindrical portion 9 and a second cylindrical portion 33 to be protected.

[0093] The second cylindrical portion 33, coaxial and of greater diameter than the first cylindrical portion 9, has a second lateral wall 34 which extends between two ends 36: a first end 50 for example upper, and a second end 51 for example lower, and which terminates with an annular edge 35 at each of its ends 36. This second lateral wall 34 has an inner face 37 and an outer face 38, and delimits a hollow inner volume 39 open at its ends 36.

[0094] To protect the ends 36 of the second cylindrical portion 33 (pinion 31), the tools 2 of the tooling 1 include a second flat annular body 40, also circular and with axis X, in addition to their flat annular body 3 intended to protect the ends 22 of the first cylindrical portion 9 (pinion 30).

[0095] This second flat annular body 40 has an inner radius Ri and an outer radius R e larger than those of the flat annular body 3. More precisely, the inner radius n is greater than the outer radius r e .

[0096] It also includes an inner cylindrical face 41, an outer cylindrical face 42 and two flat annular faces 43, one of which is a flat annular support face 44, delimited by an inner perimeter edge 45 and an outer perimeter edge 46, which is intended to be placed against the corresponding end annular edge 35 of the second cylindrical portion 33 as illustrated in figures 9 to 11.

[0097] A second cylindrical retaining rim 47, perpendicular to the flat annular support face 44, is also provided from the inner perimeter edge 45 or the outer perimeter edge 46 depending on the variants.

[0098] In figures 9 to 12, the second cylindrical retaining rim 47 borders internally the flat annular bearing face 44 on the two tools 2. Thus, when the tool 2 is placed on the part 11, the second cylindrical rim 47 is in contact with the smooth inner face 37 of the second lateral wall 34 and is advantageously not in contact with the teeth 32 of the pinion 31 which extends on the outer face 38 to the ends 36 of the second lateral wall 34.

[0099] On the contrary, the cylindrical retaining rim 14 borders externally the flat annular bearing face 7 of the first flat annular body 3 on the two tools 2, because, on the pinion 30, the teeth 32 of the outer face 27 do not extend to the ends 22 of the lateral wall 21 and leave a portion of wall 48 smooth with which the cylindrical rim 14 rests.

[0100] Depending on the variants, all combinations are nevertheless conceivable for the arrangement of the cylindrical retaining rims 14 and the second cylindrical retaining rims 47, which can be identical or different on the same tool 2, or from one tool 2 to another.

[0101] As with the annular body 3, an annular layer 17 of a solid thermal insulator may be provided on the flat annular bearing face 44, which may be identical or different in its composition and / or shape from that of the flat annular bearing face 7. In the quenching assembly 28, this annular layer 17 is found to be intercalated between the flat annular bearing face 44 and the corresponding end annular edge 35 of the second cylindrical portion 33 as illustrated in figures 9 to 11.

[0102] In the embodiment shown, the tool 2 also includes four inclined connecting arms 49 which connect the annular body 3 to the second flat annular body 40. These connecting arms 49 are distributed according to a regular radial arrangement, that is to say arranged radially with the same angle of spacing between the arms.

[0103] Another example of a hardening tool 1, intended to equip a part 11 with two cylindrical portions 9 of different types, has been shown in Figure 12.

[0104] In this example, the first cylindrical portion 9 is a cylindrical pinion 30 which protrudes above but not below the second cylindrical portion 33, which is a coaxial cylindrical pinion 31 of greater diameter.

[0105] Tooling 1 then comprises two different tools 2.

[0106] The upper tool 15, similar to that of figures 9 to 11, comprises two flat annular bodies 3 and 40 joined by connecting arms 49, and has two flat annular support faces 7 and 44 capable of protecting both the annular end edge 8 of the upper end 23 of the first cylindrical portion 9 and the annular end edge 35 of the upper end 36 of the second cylindrical portion 33.

[0107] The lower tool 16, simpler and similar to that of figures 1 to 8, comprises only a single flat annular body 3 with a single flat annular support face 7 disposed against the annular end edge 35 of the lower end 36 of the second cylindrical portion 33.

Claims

DEMANDS [Claim 1] A hardening tool (1) for the prevention of deformation of a workpiece (11) with at least one hollow, cylindrical (9) or frustoconical (10) portion, a hardening tool (1) characterized in that it comprises at least two anti-deformation steel tools (2), each comprising: - a flat annular body (3), which comprises a flat annular support face (7) extending between an inner perimeter edge (12) and an outer perimeter edge (13); and - a cylindrical retaining rim (14), perpendicular to the flat annular support face (7), which starts from said inner (12) or outer (13) perimeter edge and moves away from the flat annular body (3) - in that at least one of the tools (2) further comprises an annular layer (17) of solid thermal insulation on at least one of its flat annular support faces (7, 44). [Claim 2] Hardening tooling (1) according to the preceding claim, characterized in that at least one of the tools (2) further comprises: - a second flat annular body (40), coaxial and of greater diameter than said flat annular body (3), which has a second flat annular support face (44) extending between a second inner perimeter edge (45) and a second outer perimeter edge (46); - a second cylindrical retaining rim (47), perpendicular to the second flat annular support face (44), which extends from said second inner (45) or outer (46) perimeter edge and away from the second flat annular body (40); and - at least one inclined connecting arm (49), which connects the flat annular body (3) with the second flat annular body (40). [Claims] Quenching tool (1) according to the preceding claim characterized in that said tool (2) comprises at least two inclined connecting arms (49), distributed radially around the flat annular body (3) with a constant angular spacing. [Claim 4] Quenching tool (1) according to any one of the preceding claims characterized in that the annular layer (17) is made of ceramic material. [Claims] Quenching tooling (1) according to the preceding claim characterized in that said annular layer (17) is formed of a plate (18), a set of juxtaposed blocks (19), a wound strip or cord (20). [Claim 6] A tempering assembly (28) characterized in that it comprises: - a steel part (11), with at least one hollow, cylindrical (9) or frustoconical (10) portion, this hollow, cylindrical (9) or frustoconical (10) portion having a lateral wall (21) extending between a first end (22, 23) and a second end (22, 24) and terminating in an annular end edge (8) at each of its ends (22); and - a hardening tool (1) according to any one of the preceding claims, comprising an anti-deformation tool (2) mounted on each of the ends (22) of the side wall (21), with its flat annular support face (7) disposed against and covering the annular end edge (8) of the end (22) on which the tool (2) is mounted and with its cylindrical retaining rim (14) bearing against an inner (26) or outer (27) face respectively of the side wall (21). [Claim 7] A quenching assembly (28) according to the preceding claim characterized in that said flat annular bearing face (7) has dimensions which correspond substantially to those of the annular end edge (8) which it covers. [Claim 8] Quenching assembly (28) according to claim 6 or 7 where the quenching tooling (1) is dependent on claim 2 characterized: - in that the steel part (11) further comprises a second hollow, cylindrical (33) or frustoconical portion, coaxial and of a diameter greater than said hollow, cylindrical (9) or frustoconical (10) portion, comprising a second lateral wall (34) which extends between a first end (50, 36) and a second end (51, 36) and which terminates in an annular end edge (35) at each of its extremities (36); and - in that the second flat annular support face (44) is disposed against and covers one of the end annular edges (35) of the second side wall (34); and the second cylindrical retaining rim (47) is in contact with an inner (37) or outer (38) face respectively of the second side wall (34). [Claim 9] A quenching assembly (28) according to any one of claims 6 to 8 characterized in that the steel part (11) is a gear part (29), preferably a cylindrical (30, 31) or conical pinion; or a bearing part, preferably a plain bearing or a rolling ring. [Claim 10] A method for limiting the deformation of the ends (22, 36) of a hollow, cylindrical (9) or frustoconical (10) portion of a steel part (11) subjected to a quenching heat treatment, characterized in that it comprises the following steps: - supply of a steel part (11), with at least one hollow, cylindrical (9) or frustoconical (10) portion, this hollow, cylindrical or frustoconical portion having a lateral wall (21) which extends between a first end (22, 23) and a second end (22, 24) and terminates with an annular end edge (8) at each of its ends (22), - supply of a hardening tool (1) according to claim 1, - formation of a quenching assembly (28) by placing an anti-deformation tool (2) of the quenching tooling (1) on each end (22) of the side wall (21), with its flat annular support face (7) positioned against and covering the annular end edge (8) of the end (22) on which the tool (2) is mounted and with its cylindrical retaining rim (14) bearing against an inner (26) or outer (27) face respectively of the side wall (21), - subjecting the quenching assembly (28) to a gas quenching heat treatment.

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