Method and unit for manufacturing an elongated intermediate part by hot forging - Patents.com

Abstract

Method and unit for manufacturing an elongated intermediate part by hot forging, the method for manufacturing by forging an elongated intermediate metal alloy part (1) along a longitudinal axis (Z) comprises the steps of: manufacturing by hot forging an elongated blank with at least one zone of small cross-sectional change, shaping the blank to obtain a semi-finished product elongated along the longitudinal axis with a central part and first and second parts of enlarged cross-section extending on either side of the central part along the direction of the longitudinal axis, the shaping of the blank comprising the production of the first part of the enlarged cross-section of the semi-finished product by hot forging and the production of the second part of the enlarged cross-section of the semi-finished product by hot forging selected from the upsetting, spinning, die forging or back extrusion techniques, and hot drawing the semi-finished product to obtain the intermediate part (1).

Description

[Technical field]

[0001] The invention relates to a method and an installation for the manufacture by hot forging of an intermediate part of total length L made of a metal alloy, elongated along an axis Z, which intermediate part comprises a central part with at least one area of ​​small change in cross section and two parts of enlarged cross section located on either side of the central part. [Background technology]

[0002] Typically, a part such as an aircraft engine shaft is made by performing the following successive operations: the manufacture of an elongated blank with a small cross-sectional variation by hot extrusion or open die drawing, then the production by hot forging, e.g. via hot extrusion, of a section of enlarged cross section, called the head, located e.g. at one of the ends of the blank, and finally machining to reduce the transverse dimension of the central section while retaining the section of enlarged cross section at the end of the central section opposite the head along the longitudinal direction of the part.

[0003] However, such a method is not entirely satisfactory. In fact, elongated blanks of small cross-sectional variation have, over the entire length of the blank, a transverse dimension whose value is set by the transverse dimension of the largest cross-section of the section (excluding the head) and therefore in particular by the transverse dimension of the section of enlarged cross-section of the section opposite the head along the longitudinal direction, so that machining is necessary to reduce the transverse dimension of the central section and to obtain the desired final shape of the central section. As a result, given the large length of the central section for the applications mentioned above, this leads to relatively large losses of material and therefore high manufacturing costs, more particularly when the parts are made from so-called precious metal alloys, i.e. containing relatively large amounts of expensive alloying elements, such as maraging steels, superalloys or titanium alloys. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2019 / 141798A1 Brochure Summary of the Invention [Problem to be solved by the invention]

[0005] The aim of the present invention is to provide a method and an installation for the manufacture of elongated intermediate parts of a metal alloy as previously described, at reduced cost. [Means for solving the problem]

[0006] To that end, the present invention provides a method for the manufacture by forging of an intermediate part made of a metal alloy, the intermediate part being elongated along a longitudinal axis, the intermediate part comprising a central part with at least one zone of small cross-sectional variation, the cross-sectional surface area of ​​the or each zone of small cross-sectional variation varying by at most 20% along said zone, the intermediate part further comprising a first portion of enlarged cross-section and a second portion of enlarged cross-section located on either side of the central part along the longitudinal axis, the method further comprising: - producing by hot forging a blank elongated along its longitudinal axis, the blank comprising at least one area of ​​small cross-sectional variation; - shaping the blank to obtain a semi-finished product elongated along a longitudinal axis with a central portion and a first portion of enlarged cross section and a second portion of enlarged cross section extending on either side of the central portion along the direction of the longitudinal axis, the shaping of the blank comprising the production of the first portion of enlarged cross section of the semi-finished product by hot forging and the production of the second portion of enlarged cross section of the semi-finished product by hot forging selected from the upsetting, spinning, die forging or back extrusion techniques; - hot drawing the semi-finished product to obtain an intermediate part; The present invention relates to a method comprising the steps of:

[0007] The method according to the invention may comprise one or more of the following features, taken individually or in any technically possible combination: The metal alloy is selected from superalloys, titanium alloys, and steels, more particularly, the steels are selected from the following list: structural hardened steels and alloyed martensitic steels. - the length of the intermediate part is not less than 800 mm and the ratio between the length of the intermediate part and the maximum transverse dimension of the central part of the intermediate part is not less than 2.5; - the cross-sectional surface area of ​​the or each area of ​​small cross-sectional variation varies by at most 10% along the length of said area, preferably the cross-sectional surface area of ​​the or each area of ​​small cross-sectional variation is constant along said area. - the cumulative length of the one or more areas of small cross-sectional changes along the longitudinal axis is greater than or equal to 40% of the length of the intermediate part, preferably greater than or equal to 60% of the length of the intermediate part, and even more preferably greater than or equal to 70% of the length of the intermediate part. - the centre of the first portion of the enlarged cross-section and / or the centre of the second portion of the enlarged cross-section along the longitudinal direction of the intermediate part is positioned at a distance from the corresponding end of the intermediate part that is no more than 25% of the length of the intermediate part, preferably no more than 15% of the length of the intermediate part. - The first part of the enlarged cross section of the semi-finished product is produced by upsetting, spinning, die forging or backward extrusion techniques. the second part of the enlarged cross section of the semifinished product is produced by upsetting, preferably the first part of the enlarged cross section is produced by upsetting or die forging. the second part of the enlarged cross section of the semifinished product is produced by die forging, preferably the first part of the enlarged cross section is produced by upsetting or die forging. The production of the first part of the enlarged cross section of the semifinished product and the production of the second part of the enlarged cross section of the semifinished product are carried out successively. The production of the first part of the enlarged cross section of the semifinished product and the production of the second part of the enlarged cross section of the semifinished product are carried out simultaneously, more particularly on the same tool. the semi-finished product is not heated between the production of the second portion of the enlarged cross section of the semi-finished product and the hot drawing. The production of the second part of the expansion zone and the hot drawing are carried out in the same tool.

[0008] The present invention relates to a method for manufacturing an elongated part made of a metal alloy, comprising the steps of: - manufacturing an intermediate part using the method previously described; - finishing the intermediate part to obtain a part, the finishing including more particularly machining; The present invention further relates to a method comprising the steps of:

[0009] According to a particular feature of the method, the parts are selected from axles, drive shafts, parts for landing gear, riser pipes for pumps intended for oil or gas extraction, underwater valves, in particular for engines for large ships such as liners or supertankers, and missile launchers.

[0010] The invention relates to an installation for the production by forging of an intermediate part made of a metal alloy, the intermediate part being elongated along a longitudinal axis, the production installation being intended to be used for the implementation of a method, - a housing defining a longitudinal axis intended to receive an elongated blank along the longitudinal axis, the blank comprising at least one area of ​​small cross-sectional variation or a semi-finished part elongated along the longitudinal axis, the semi-finished part comprising a rod portion comprising at least one area of ​​small cross-sectional variation and a first part of enlarged cross-section; - a device for shaping a blank or semi-finished part received in a housing, so as to form a semi-finished product having a central portion and a first portion of enlarged cross section and a second portion of enlarged cross section located on either side of the central portion along the direction of the longitudinal axis, the device comprising a device for producing at least the second portion of enlarged cross section of the semi-finished product by hot forging, by swaging, by spinning or by back extrusion techniques; - a hot stretching device configured to hot straighten the semi-finished product to form an intermediate part; The present invention further relates to a facility comprising:

[0011] The installation according to the invention may comprise one or several of the features individually or in any technically possible combination. the hot stretching device is configured for hot straightening the semi-finished product received in the housing; - the hot drawing device comprises a drawing punch which is translationally movable relative to the housing along a direction perpendicular to the longitudinal axis of the housing from a rest position to a drawing end position, the movement of the drawing punch from the rest position to the drawing end position resulting in hot distortion correction of the semi-finished product received in the housing to obtain an intermediate part. - the apparatus further comprises a die defining a housing, the die comprising a fixed part and a movable part, said movable part of the die being movable in translation relative to said fixed part in the direction of a longitudinal axis of the housing between a closed position in which the movable part is in contact with the fixed part and a spaced position in which the movable part is spaced apart from the fixed part by an extension distance, the movement resulting in an extension of the housing by a length equal to the extension distance. - the hot drawing device further comprises, for each drawing punch, a receiving housing for the drawing punch configured to receive an end area of ​​the drawing punch when the drawing punch moves from its rest position to its drawing end position, and insertion of the drawing punch into the corresponding receiving housing causes the movable part of the die to move in translation relative to the fixed part of the die from the closed position to a spaced position so as to straighten the semi-finished product received in the housing. the installation further comprises a support to which the or each actuating member and the or each drawing punch are fastened, the support being arranged in the following positions: a rest position in which the or each operating member and the or each drawing punch occupy their rest position; a forming end position in which the or each operating member occupies its forming end position; - the or each drawing punch occupies its end position; , and is translationally movable relative to the housing along a direction parallel to the direction of movement of the or each actuating member and the direction of movement of the or each drawing punch, so as to occupy successively. - The equipment is used as a forging press tool. The installation as described above forms a forging press tool.

[0012] The invention further relates to the use of an installation as described above as a forging press tool.

[0013] The invention will be better understood on reading the following description, given purely by way of example and made with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0014] [Figure 1] 1 is a schematic diagram of an intermediate part manufactured by a method according to the invention according to a first embodiment; FIG. [Diagram 2] 2 is a schematic diagram of the intermediate part shown in FIG. 1 in a section along plane F-F' according to one embodiment. [Diagram 3] FIG. 3 is a schematic view similar to FIG. 2 of an intermediate piece according to a variant. [Figure 4] 5 is a schematic diagram of an intermediate part manufactured by the method according to the invention according to a variant; [Diagram 5] FIG. 2 is a schematic representation of a blank used in the context of the method according to the invention; [Figure 6] 1 is a schematic diagram of a semi-finished product produced within the scope of the method according to the invention; [Figure 7] 1 is a schematic diagram of a semi-finished part produced within the context of the method according to the invention; [Figure 8] FIG. 13 is a schematic diagram of an intermediate part according to a deformation. [Figure 9] FIG. 1 shows a schematic perspective view of an installation for manufacturing an intermediate part by forging according to a first embodiment; [Figure 10] FIG. 10 is a schematic longitudinal section along a vertical plane of the installation shown in FIG. 9. [Figure 11] FIG. 10 is a schematic diagram of a portion of the installation shown in FIG. [Figure 12] FIG. 4 shows a schematic perspective view of an installation for manufacturing an intermediate part by forging according to a second embodiment; [Figure 13] FIG. 13 is a schematic longitudinal section along a vertical plane of the installation shown in FIG. 12. [Figure 14] FIG. 13 is a schematic top view of some elements of the equipment shown in FIG. [Figure 15] FIG. 1 is a schematic diagram of the forming of a section of enlarged cross section by swaging from a blank which is hollow at its ends. [Figure 16] FIG. 1 is a schematic diagram of the forming of a section of enlarged cross section by needle upsetting from a blank that is hollow at its end. [Figure 17] FIG. 1 is a schematic diagram of the forming of an enlarged cutting surface by die forging from a solid blank. [Figure 18] FIG. 1 is a schematic diagram of the forming of an enlarged cross-section section by backward extrusion from a solid blank. [Figure 19] FIG. 1 is a schematic diagram of the forming of an enlarged cutting surface by upsetting from a solid blank. [Figure 20] FIG. 13 is a schematic diagram of the forming of an enlarged cross-section portion by upsetting from a hollow blank with a lost mandrel. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The invention relates to a method for manufacturing, by forging, an elongated intermediate piece 1 made from a metal alloy.

[0016] An example of an intermediate part 1 produced by the manufacturing method according to a first embodiment of the invention is shown diagrammatically in FIG.

[0017] The intermediate part 1 is elongated along a longitudinal axis Z and has a total length L. The intermediate part 1 comprises a central portion 3 with at least one area of ​​small cross-sectional change and a first portion 5 of enlarged cross-section and a second portion 5' of enlarged cross-section located on either side of the central portion 3 along the direction of the longitudinal axis Z.

[0018] The central portion 3 and the or each area of ​​small cross-sectional variation are elongated along a longitudinal axis Z.

[0019] Throughout this description, the term "cross section" refers to a cross section perpendicular to the longitudinal axis Z.

[0020] Throughout this description, the term "area of ​​small cross-sectional variation" refers in particular to an area whose cross-sectional surface area varies along said area, i.e. along the longitudinal axis Z, by at most 20%. Such variation is estimated by the ratio between the difference between the surface area of ​​the largest cross-section and the surface area of ​​the smallest cross-section and the average surface area in the cross-section of at least one cross-section that is almost unchanged. More specifically, the variation is at most 10%. Even more specifically, the cross-section of said area is identical along said area. In other words, the variation as defined above is zero. In such cases, the term "area of ​​constant cross-section" will be used hereafter.

[0021] The central portion 3 has a cumulative length L0 of one or more areas along the longitudinal axis Z where the cross section hardly changes that is equal to or greater than 40% of the length L of the intermediate part 1. By way of example, the cumulative length L0 of one or more areas of the central portion 3 where the cross section hardly changes is equal to or greater than 60% of the length L of the intermediate part 1, in particular, equal to or greater than 70% of the length L of the intermediate part 1.

[0022] Preferably, the first portion 5 of the enlarged cross section and the second portion 5' of the enlarged cross section are adjacent to areas of small cross-sectional change of the central portion 3 along the direction of the longitudinal axis Z, i.e. without any other portions of the part being interposed.

[0023] According to one embodiment, the central portion 3 consists of an area of ​​small cross-sectional variation, more particularly, the central portion 3 consists of an area of ​​constant cross-section.

[0024] According to a variant (not shown), the central portion 3 comprises, along the direction of the longitudinal axis Z, a number of zones in which the cross section changes little and at least one intermediate portion arranged between the zones in which the cross section changes little.

[0025] According to another variant (not shown), the central portion 3 comprises a number of areas of constant cross section and at least one intermediate portion arranged between the areas of constant cross section.

[0026] In the example shown in FIG. 1, the central portion 3 consists of an area of ​​constant cross section and of a first portion 5 and a second portion 5' of enlarged cross section which adjoin the central portion 3 along the direction of the longitudinal axis Z.

[0027] The first and second portions 5, 5' of the enlarged cross section are preferably located near the respective ends 4, 4' of the intermediate part 1. More specifically, each portion 5, 5' of the enlarged cross section along the direction of extension Z of the intermediate part 1 is located at a respective distance L1, L2 from the corresponding end 4, 4' that is equal to or less than 25% of the length L of the intermediate part 1. More specifically, the centre of each portion 5, 5' of the enlarged cross section is located at a respective distance L1, L2 from the corresponding end 4, 4' that is equal to or less than 15% of the length L of the intermediate part 1.

[0028] Each of the enlarged cross-sectional portions 5, 5' has a cross-section with a respective minimum surface area Amin corresponding to their minimum cross-section. For each of the enlarged cross-sectional portions 5, 5', the cross-sectional surface area Amin is greater than the maximum cross-sectional surface area A of at least one of the areas of the central portion 3 where the cross-section changes little, in particular the maximum cross-sectional surface area A of the or each area of ​​the central portion 3 of small cross-sectional change.

[0029] More specifically, the cross-section of the minimum surface area Amin of each of the enlarged cross-sectional portions 5, 5' has a maximum dimension D1, D2 that is greater than the maximum dimension D of the maximum cross-section of at least one of the areas of the central portion 3 where the cross-section changes little, specifically the maximum dimension D of the maximum cross-section of that or each area of ​​the central portion 3 where the cross-section changes little.

[0030] The maximum dimension of the cross-section means in particular the outer diameter of the cross-section in the case of a circular cross-section, or the diagonal of the cross-section in the case of a polygonal cross-section, such as a square or hexagonal cross-section.

[0031] According to one embodiment, the first and second portions 5, 5' of the enlarged cross section have the same shape. According to a variant, as shown in the figure, the first and second portions 5, 5' of the enlarged cross section have different shapes, such as different lengths and / or transverse dimensions.

[0032] For example, the first portion 5 of the enlarged cross section and / or the second portion 5′ of the enlarged cross section may be - a certain cross-sectional shape, more specifically a circular or cylindrical shape, - an axisymmetric shape of cross section variable along the longitudinal axis Z, more specifically a trumpet-shaped, conical or other shape, - Non-axisymmetric shapes, more specifically yoke-shaped, gimbal-shaped, or any other suitable complex shapes The shape is selected from:

[0033] In the case of an enlarged cross-sectional portion 5, 5' having a constant cross-sectional shape, i.e. a constant cross-sectional area along said enlarged cross-sectional portion, the cross section of the minimum surface area Amin corresponds to any cross section of the enlarged cross-sectional portion 5, 5' under consideration.

[0034] If the first portion 5 of the enlarged cross-section and / or the second portion 5' of the enlarged cross-section has an annular or cylindrical shape, this portion 5, 5' of the enlarged cross-section is, according to one embodiment, positioned at a distance from an end 4, 4' of the intermediate part 1 or, according to a variant, positioned at one end 4, 4' of the intermediate part 1 so as to form a flange.

[0035] In the case of an enlarged cross-sectional portion 5, 5' having a cross-sectional shape that varies along the longitudinal axis Z, the minimum surface area Amin of the cross-section corresponds to the particular surface area at the cross-section of the enlarged surface area of ​​the cross-sectional portion 5, 5' under consideration, where the surface area of ​​the enlarged cross-sectional portion 5, 5' is smallest.

[0036] The first portion 5 of the enlarged cross section and the second portion 5' of the enlarged cross section advantageously have different shapes selected from any combination of the shapes mentioned above.

[0037] The intermediate part 1 shown in FIG. 1 is a solid part.

[0038] According to a first variant, illustrated in FIG. 4, the intermediate part 1 is a hollow part, more particularly a tubular part.

[0039] According to a second variant, the central part 3 of the intermediate part 1 is solid and at least the second part 5' of the enlarged cross section is hollow and forms one of the ends of the intermediate part 1. By way of example, the first part 5 of the enlarged cross section and the second part 5' of the enlarged cross section are hollow and each form one end of the intermediate part 1.

[0040] According to a third variant, the intermediate part 1 is a composite part comprising a core formed by a lost mandrel as described in patent application WO 2019 / 141798 A1, made from a first metal alloy, and a casing made from a second metal alloy.

[0041] According to an embodiment of the invention, the intermediate part 1 is a part of rotation about the axis Z.

[0042] By way of example, the central part 3 of the intermediate part 1 is a part of rotation about the axis Z. The central part 3 of the intermediate part 1 is for example a cylinder, either solid or hollow.

[0043] According to one embodiment, the cross section of the solid or hollow cylinder is circular, and the maximum transverse dimension D corresponds to the diameter of the circular straight cross section. In the case of a hollow cylinder, the diameter of the circular straight cross section refers to the outer diameter of the cylinder.

[0044] According to a variant of the invention, the solid or hollow cylinder has a square cross section and the maximum transverse dimension D corresponds to the diagonal of said square cross section. In the case of a hollow cylinder, the diagonal of the square cross section means the outer diagonal of the square cross section.

[0045] According to another variant, the solid or hollow cylinder has a hexagonal cross section and the maximum transverse dimension D corresponds to the dimension of a circle circumscribing said hexagonal cross section.

[0046] By way of example, the length L of the intermediate part 1 is 800 mm or more and the ratio L / D between the length of the intermediate part 1 and the maximum transverse dimension D of the central portion 3 is 2.5 or more. More particularly, the ratio L / D is 5 or more, in particular 15 or more, such as 20 or more, and / or the length L of the intermediate part 1 is 1 m or more, in particular 1.5 m or more, such as 2 m or more, it being possible to combine the length L with the ratios L / D listed above depending on the desired final shape of the intermediate part 1.

[0047] The intermediate piece 1 is made from a metal alloy. In particular, the intermediate piece 1 is made from one of the following materials: steel, more particularly a steel selected from the following list: - structural hardened steels, in particular structural hardened martensitic steels such as 15-5PH, 17-4PH, ML340, Maraging 250, Marvel 18, Maraging 300, Maraging 350, MLX19 or MLX20. - Alloy martensitic steels such as Steel 300M. - Superalloys, more specifically nickel-based superalloys such as alloy 718. - Titanium alloys such as Ti-6-Al-4V, Ti-5333, or Ti 10.2.3.

[0048] The steels listed above are steels with high mechanical properties.

[0049] The intermediate part 1 is in particular intended for the manufacture of parts selected from: - Axles for railway or motor vehicles etc. Drive shafts such as for helicopter rotors or pump shafts, more particularly drive shafts for example for wind turbines or for the automotive industry, such as cars, trucks, tractors, or shafts for gas turbines or turbojets. - Landing gear parts such as landing gear rod sections or landing gear wheel axles. - Riser pipes for pumps etc. for oil or gas extraction. - Specifically, underwater valves for engines of larger vessels such as ships or supertankers. - Missile launcher.

[0050] The method according to the invention comprises the following steps. An elongated blank 6 with at least one area of ​​small cross-sectional variation is produced by hot forging. The blank 6 is shaped to obtain a semi-finished product 11 comprising a central portion 12 and a first portion 13 of enlarged cross section and a second portion 14 of enlarged cross section extending on either side of the central portion 12 . The semi-finished product 11 is hot drawn to obtain the intermediate part 1.

[0051] The steps of the method are described in more detail later in this description.

[0052] The hot forging step to obtain the blank 6 is in particular carried out on a steel billet.

[0053] The billet is typically obtained from a forged ingot or from a forged ingot that is subsequently rolled depending on the final diameter of the billet. Before hot forging, the billet is heated in a treatment furnace at a temperature and for a period of time suitable to bring about hot deformation of the material of the billet during forming. The temperature and the period of heating are selected by the person skilled in the art depending on the composition of the alloy. The treatment time is selected to obtain the same temperature between the skin and the core of the billet.

[0054] The billet is then transferred to a hot forging tool, which is conventional and will not be described in detail below.

[0055] The billet is then hot forged in a hot forging tool, for example by hot extrusion, open die forging, radial forging, die forging or rolling.

[0056] At the end of said step, an elongated blank 6 is obtained with a longitudinal axis Z, which comprises at least one zone of small cross-sectional variation extending along said longitudinal axis Z. The cross section of said zone is, for example, circular or polygonal, for example having a square or hexagonal shape.

[0057] The blank 6 is more specifically a cylindrical blank of revolution.

[0058] The blank 6 may be hollow or solid.

[0059] An example of a blank 6 is shown diagrammatically in Figure 5. In the example, the blank 6 consists of an area of ​​constant cross section.

[0060] The blank 6 is shaped to obtain a semi-finished product 11 as shown diagrammatically in FIG.

[0061] The semi-finished product 11 is elongated with a longitudinal axis Z. The semi-finished product 11 comprises a central portion 12 and a first portion 13 of enlarged cross-section and a second portion 14 of enlarged cross-section extending along the direction of the longitudinal axis Z on either side of the central portion 12. The central portion 12 of the semi-finished product 11 comprises at least one area of ​​small cross-sectional change. The central portion 12 has a longitudinal axis Z.

[0062] The first portion 13 of the enlarged cross-section and the second portion 14 of the enlarged cross-section each have a cross-section of a minimum surface area that is greater than the surface area of ​​the maximum cross-sectional area of ​​at least one region of the central portion 12 of the small cross-sectional change, more specifically, the surface area of ​​the maximum cross-sectional area of ​​the or each region of the central portion 12 of the small cross-sectional change.

[0063] The step of shaping the blank 6 includes the production of a first portion 13 of enlarged cross section by hot forging, in particular by die forging, upsetting, spinning or back extrusion techniques, followed by the production of a second portion 14 of enlarged cross section by hot forging, in particular by die forging, upsetting, spinning or back extrusion techniques.

[0064] The term "spinning" refers to the shaping of a blank 6 that is hollow at at least one end by only radial movement of material perpendicular to the longitudinal axis Z of the elongated blank 6.

[0065] According to a specific embodiment, the first portion 13 of the enlarged cross section and the second portion 14 of the enlarged cross section are each hot forged by one of the following methods: swaging, specifically swaging in a needle, spinning, or back extrusion. The hot forging methods are shown diagrammatically in Figures 15-20 and described hereinafter for the second portion 14 of the enlarged cross section.

[0066] The first portion 13 of the enlarged cross section and the second portion 14 of the enlarged cross section can be made by the same type of hot forging, specifically selected from upsetting in a needle, spinning, or back extrusion. More specifically, the first portion 13 of the enlarged cross section and the second portion 14 of the enlarged cross section are made by upsetting or die forging.

[0067] In a variant, the first portion of the enlarged cross section 13 and the second portion of the enlarged cross section 14 are made by different types of hot forging selected from any combination of the types of hot forging mentioned above. More specifically, the first portion of the enlarged cross section 13 is made by upsetting and the second portion of the enlarged cross section 14 is made by die forging, or the first portion of the enlarged cross section 13 is made by die forging and the second portion of the enlarged cross section 14 is made by upsetting.

[0068] According to one embodiment, the first portion 13 of the enlarged cross section and the second portion 14 of the enlarged cross section are produced successively, for example in different tools.

[0069] In such a case, the blank 6 is transferred to a first hot forging tool, where it undergoes hot forging, in particular die forging, upsetting, spinning or back extrusion, in order to obtain the semi-finished part 16 .

[0070] An example semi-finished part 16 is shown diagrammatically in Fig. 7. The semi-finished part 16 comprises a rod portion 15 with at least one area of ​​small cross-sectional changes and a first portion 13 of enlarged cross-section. Each area of ​​small cross-sectional changes is identical to a corresponding area of ​​small cross-sectional changes in the blank 6.

[0071] The thereby obtained semi-finished part 16 is then transferred to a forming tool, in which the second portion 14 of enlarged cross section is produced by hot forging, in particular by die forging, upsetting, spinning or back extrusion, in order to obtain the semi-finished product 11. The forming by hot forging to obtain the second portion 14 of enlarged cross section is in particular carried out with the aid of an installation which will be explained in more detail below with reference to Figures 9 to 11.

[0072] The second portion 14 of the enlarged cross section is preferably made by swaging or die forging. In the case of swaging, the swaging ratio during the step of producing the second portion 14 of the enlarged cross section is comprised in particular between 1.20 and 1.25. The swaging ratio usually corresponds to the ratio between the diameter before swaging and the diameter after swaging.

[0073] According to a variant, the first part 13 of the enlarged cross section and the second part 14 of the enlarged cross section of the semifinished product 11 are produced simultaneously, more specifically in the same tool. In such a case, the first part 13 of the enlarged cross section and the second part 14 of the enlarged cross section are produced by hot forging, more specifically by the die forging technique, the upsetting technique, the spinning technique or the backward extrusion technique. The forming by hot forging to obtain the first part 13 of the enlarged cross section and the second part 14 of the enlarged cross section is carried out more specifically with the aid of an installation which will be described in more detail later with reference to Figures 12 to 14.

[0074] Following shaping by hot forging to form a second portion 14 of enlarged cross section of the semi-finished product 11 there is hot drawing of the semi-finished product 11 to straighten it and obtain the intermediate part 1 .

[0075] During the hot drawing step, the semi-finished product 11 is stretched to plastically deform the metal alloy, which serves to apply a permanent deformation to the semi-finished product 11 in order to improve the straightness of the semi-finished product 11.

[0076] Within the concept of the invention, the main function of hot drawing is to improve the straightness of the semifinished product 11. Indeed, the forming step may result in unwanted straightness defects in the final part in the central portion 12 of the semifinished product 11. The drawing step serves in particular to reduce the deviations from a perfectly straight shape in the central portion 12 in the transverse direction perpendicular to the longitudinal axis Z of the semifinished product 11. The hot drawing step is preferably carried out in such a way that the deviations in the transverse direction from a perfectly straight shape in the central portion 12 are reduced to a maximum of 2-5 mm per meter of the central portion 12.

[0077] The hot drawing step also serves to modify the angle between the central portion 12 and the portions 13, 14 of the enlarged cross section of the semifinished product 11 and, if appropriate, to partially relieve internal stresses associated with the shaping of the semifinished product 11.

[0078] By way of example, in addition to the previously mentioned distortion correction, the stretching step has the effect of stretching the semi-finished product 11 by a length equal to a maximum of 20-30 mm per 2 meters length of the semi-finished product 11 .

[0079] Advantageously, the production of the second portion 14 of enlarged cross section by hot forging and forming by hot drawing is carried out in the same tool, more particularly using an installation as previously described with reference to Figures 9 to 11.

[0080] According to a variant, the hot drawing is carried out with a tool different from that used to produce the second portion 14 of enlarged cross section. More specifically, the hot drawing is carried out with any tool provided to straighten or straighten the shaft by drawing.

[0081] Preferably, an intermediate heating is performed on the semi-finished product 11 before hot drawing.

[0082] Preferably, the average temperature of the semi-finished product 11 is reduced by a maximum of 200° C. between the production by hot forging and the production by hot drawing of the second portion 14 of enlarged cross section.

[0083] The invention further relates to a method for producing a finished metal alloy component (not shown), the method comprising: - manufacturing an intermediate part 1 using a method as previously described, - finishing the intermediate part 1 to obtain a finished part; Includes.

[0084] The finishing step more specifically includes a machining step.

[0085] According to one embodiment, the shape of the intermediate part 1 is very close to that of the finished part, and the intermediate part 1 is machined only to remove a small excess thickness, typically less than 10 mm, or even an excess thickness of a few millimeters, in order to obtain a functional surface, if appropriate.

[0086] According to one variant, one of the portions 5, 5' of the enlarged cross section of the intermediate part 1 comprises a ring 7 of the cross section with a surface area greater than that of the remaining portion 5, 5' of the enlarged cross section, the machining step comprising the removal of said ring 7. The ring 7 belonging to the corresponding portion 14 of the enlarged cross section of the semifinished product 11 serves to form a grip in the second portion 14 of the enlarged cross section of the semifinished product 11 for use in hot drawing in embodiments in which the difference between the maximum surface area of ​​the cross section of the corresponding enlarged surface area of ​​the cross section of the finished part and the maximum surface area of ​​the cross section of the central portion of the finished part is small. An example of an intermediate part 1 with such a ring 7 in the second portion 5' of the enlarged cross section is shown in FIG. 8.

[0087] According to one embodiment, when the intermediate part 1 comprises a lost mandrel as described above, the machining step includes removing the lost mandrel by machining, resulting in a hollow final part having an external shape close to that of the intermediate part 1.

[0088] Optionally, the finishing step further comprises one or more heat treatments, more specifically to achieve the mechanical properties of the required use. The finished part obtained at the end of the method is selected from: - Axles for railway or motor vehicles etc. Drive shafts such as for helicopter rotors or pump shafts, more particularly drive shafts for example for wind turbines or for the automotive industry, such as cars, trucks, tractors, or shafts for gas turbines or turbojets. - Landing gear parts such as landing gear rod sections or landing gear wheel axles. - Riser pipes for pumps etc. for oil or gas extraction. - Specifically, underwater valves for engines of larger vessels such as ships or supertankers. - Missile launcher.

[0089] The method according to the invention is advantageous. In fact, by using the production of the second portion 14 of the enlarged cross section of the semifinished product 11 by hot forging and then stretching to straighten the semifinished product 11 to obtain the intermediate part 1, it is possible to produce the central part 3 of the intermediate part 1 by direct hot forging to an outer diameter as close as possible to the outer diameter of the final part. More specifically, in the case of a central part of a certain circular cross section, it is possible to produce the central part 3 of the intermediate part 1 by direct hot forging to an outer diameter very close to the outer diameter of the central part 3 in the final part. Thereby, it is possible to prevent the material losses associated with the machining, which occur during the implementation of the known method described in the introduction, and thereby to reduce the costs associated with the manufacture of the part. Such hardening is particularly advantageous in the case of precious metal alloys, i.e. precious metal alloys with expensive alloying elements at a relatively high grade, such as steels with high mechanical properties, including maraging steels, superalloys and titanium alloys. In fact, in such cases, the effect of reducing the material losses on the cost of the part is particularly characterized. The drawing step serves to straighten the intermediate part 1 after the production of the second portion 14 of enlarged cross section. Indeed, when the outer dimensions of the central portion 3 of the intermediate part 1 are very close to those of the final part, the blank 6 or rod portion 15 of the semi-finished part 16 has a cross section with a relatively small surface area, whereby the production of the second portion 14 of enlarged cross section may result in straightness defects in the central portion 12 of the semi-finished part 11, which defects are corrected by means of a hot drawing step.

[0090] 9 to 11 show an example of an installation 50 for producing by forging an intermediate piece 1 as previously described according to a first embodiment.

[0091] The installation 50 is intended to be used to carry out the manufacturing method described above, more specifically serving to carry out the sub-step of producing the second portion 14 of enlarged cross section of the semifinished product 11 by hot forging and the step of hot drawing of the semifinished part 11 to obtain the intermediate part 1.

[0092] The installation 50 for manufacturing the intermediate part 1 by forging as previously described comprises: a housing 55 defining a longitudinal axis B, intended to receive an elongated blank 6 or a semi-finished part 16 as previously described; - a device 51 for shaping a blank 6 or a semi-finished part 16 received in a housing 55 so as to form a semi-finished product 11 as previously described, said shaping device 51 comprising a device 52 for producing by hot forging at least the second portion 14 of enlarged cross section of the semi-finished product 11; - a hot drawing device 54 configured for hot straightening the semi-finished product 11 to form an intermediate part 1; Equipped with.

[0093] The installation 50 comprises a die 53 comprising a lower die 100 and an upper die 102, and a support table 113. The die 100 is fastened in a removable manner to the support table 113. A housing 55 is formed in the die 53, more specifically by being defined by the lower die 100 and the upper die 102. A relative movement of the upper die 102 with respect to the lower die 100 serves to open the housing 55 over its entire length, specifically for the insertion of the part to be molded.

[0094] 9 to 11, the longitudinal axis B extends horizontally. In said examples, the lower die 100 and the upper die 102 each extend horizontally.

[0095] In a first embodiment shown in Figures 9 to 11, the device 52 is configured to receive a semi-finished part 16 as previously described, i.e. comprising a rod portion 15 and a first portion of enlarged cross section 13. More specifically, the housing 55 is intended to receive the semi-finished part 16 coaxially with its longitudinal axis B.

[0096] The housing 55 comprises a central portion 57 and, on either side of the central portion 57 along the direction of the longitudinal axis B, an enlarged cross-sectional first portion 58 and an enlarged cross-sectional second portion 59. In the illustrated example, the enlarged cross-sectional first portion 58 and the enlarged cross-sectional second portion 59 are adjacent to the central portion 57.

[0097] The central portion 57 is configured to receive the central portion 12 of the semifinished product 11. The central portion 57 has a shape that substantially matches the shape of the central portion 12 of the semifinished product 11. The central portion 57 comprises at least one area of ​​minor cross-sectional variation of the semifinished product 11 that is intended to receive a corresponding area of ​​minor cross-sectional variation.

[0098] The first portion 58 of the enlarged cross section of the housing 55 is configured to accommodate the semifinished product 11, and thus the first portion 13 of the enlarged cross section of the semifinished part 16. The first portion 58 of the enlarged cross section specifically comprises at least one portion with a shape that matches a portion of the first portion 13 of the enlarged cross section of the semifinished product 11, and thus the semifinished part 16.

[0099] The enlarged cross-sectional second portion 59 of the housing 55 is configured to receive the enlarged cross-sectional second portion 14 of the semifinished product 11. The enlarged cross-sectional second portion 59 specifically comprises at least one portion with a shape that matches a portion of the enlarged cross-sectional second portion 14 of the semifinished product 11 produced using the equipment 50.

[0100] In such an embodiment, the central portion 57 and the second portion 59 of enlarged cross section are intended to receive the rod portion 15 of the semi-finished part 16 .

[0101] The installation 50 further comprises a pusher 103 configured to press the upper die 102 against the lower die 100. The pusher 103 is removable. In the illustrated example, the pusher 103 is in the form of a solid block configured to bear against the upper die 102 so as to press the upper die 102 against the lower die 100. Pressing the upper die 102 against the lower die 100 has the effect of deforming the semi-finished part 16 arranged in the housing 55 such that the semi-finished part 16 is partially molded in the housing 55 in a part of the semi-finished part 16 that will not be molded later. Such molding in particular creates a wedge effect of the semi-finished part in the housing 55 that prevents a relative movement of the rod portion 15 of the semi-finished part 16 with respect to the housing 55.

[0102] The facility 50 further comprises a locking system 111, specifically shown in Fig. 9, for locking the upper die 102 to the lower die 100. By way of example, the locking system 111 comprises a number of locking openings 120, 121 provided in the upper die 102 and the lower die 100, respectively, more specifically in the appendages of the upper die 102 and the lower die 100, and a locking rod 122. In the closed configuration of the die 53 after molding, the locking openings 120, 121 are coaxial, and the locking rod 122 is designed to extend through the locking openings 120, 121 to lock the upper die 102 to the lower die 100. The locking of the upper die 102 to the lower die 100 prevents the relative movement of the rod portion 15 of the semi-finished part 16 with respect to the housing 55.

[0103] The device 52 is configured to produce the second portion 14 of enlarged cross section of the semifinished product 11 by hot forging a corresponding part of the rod portion 15 of the semifinished part 16 received in the housing 55. Said hot forging is in particular a needle upsetting technique, a die forging technique, a spinning technique or a back extrusion technique. Preferably, said hot forging is upsetting or die forging, more particularly upsetting.

[0104] To that end, the device 52 comprises at least one forming punch 60 that is adapted to be received in the housing 55 and to move in translation inside the housing 55, in particular to slide within the housing 55 along a direction of movement G shown in Fig. 10 over a maximum movement stroke. The direction of movement G of the forming punch corresponds to the direction of the longitudinal axis B of the housing 55. The movement of the forming punch 60 in the housing 55 is adapted to bring about a crushing and thus a shaping by upsetting, spinning, die forging or back-pushing techniques of a portion of the elongate portion 15 of the semifinished part 16, in particular to form the second portion 14 of enlarged cross section.

[0105] More specifically, the forming punch 60 is configured to move in translation along the direction of the longitudinal axis B from a rest position, as shown in Figures 9 to 11, in which the forming punch 60 forms the second portion 14 of enlarged cross section, to an end-forming position in which the semi-finished part 16 has been formed. More specifically, the forming punch 60 has therefore moved over a maximum travel stroke between the rest position and the end-forming position.

[0106] In the rest position, the forming punch 60 exerts no force on the blank 16. In the illustrated example, the forming punch 60 is not in contact with the blank 16 in the rest position.

[0107] The housing 55 is provided, at its longitudinal end located on the side of the second portion 59 of the enlarged cross section, with an opening 61 for the insertion of a forming punch 60 into the housing 55 .

[0108] The shape of the forming punch 60 is selected depending on the forming to be performed, more specifically depending on the shape of the enlarged cross-sectional portion 14 of the semi-finished product 11 to be produced and on the type of hot forging to be performed.

[0109] 9 to 11, the forming punch 60 is formed by a rod portion 62. More specifically, the rod portion 62 has a constant cross section. The rod portion 62 has a shape that matches the shape of a part of the housing 55 into which the rod portion 62 is inserted, provided that there is a clearance required for the movement of the rod portion 62 in the housing 55.

[0110] However, any other form of forming punch 60 can be used, depending on the shape of the enlarged cross-sectional portion of the semi-finished product 11 and the type of hot forging to be performed.

[0111] More specifically, Figure 15 shows diagrammatically an embodiment of hot forging of a portion 14 in enlarged section from a semi-finished part 16 with a hollow end, said hot forging being carried out by spinning using a forming punch 60 which displaces the material radially perpendicular to the axis B of the housing 55 of the die 53. More specifically, the forming punch 60 has a maximum transverse dimension Dp which is smaller than the maximum transverse dimension Dlog of the end of the housing 55 of the die 53, so that the forming is not carried out in a closed cavity.

[0112] FIG. 16 shows diagrammatically a variation of the embodiment of FIG. 15 in which the forming punch 60 is a needle.

[0113] 17 shows diagrammatically an embodiment of forming by hot forging the section 14 of enlarged cross section from the semi-finished part 16 with a hollow end by die forging using a forming punch 60 which displaces the material radially perpendicular to the axis Z and forms it into the shape of the cavity at the end of the housing 55. The forming punch 60 fits into the end of the housing 53 so that said die forging takes place in a closed cavity.

[0114] FIG. 18 shows diagrammatically an embodiment in which the section 14 of enlarged cross section is formed from the solid semi-finished part 16 by hot forging using a forming punch 60 which moves material along an axis B in a direction opposite to that of the punch.

[0115] FIG. 19 shows diagrammatically an embodiment in which a section 14 of enlarged cross section is formed by hot forging from a solid semi-finished part 16 by upsetting using a forming punch 60 with a flat end, which crushes the material and locally enlarges the deformed area.

[0116] FIG. 20 shows diagrammatically a variation of the embodiment of forming by hot forging with upsetting shown in FIG. 19 in preparation for forming a section 14 of enlarged cross section from a semi-finished part 16 with a lost mandrel 17 .

[0117] 9-11, the device 52 for producing the second portion 14 of the enlarged cross section further comprises an actuating member 70 which can be translated relative to the housing 55 from a rest position to an end-of-shaping position in a translation direction F shown in Fig. 10 perpendicular to the longitudinal axis B of the housing 55. More specifically, the actuating member 70 is translationally movable downwards along the vertical direction from its rest position to its end-of-shaping position.

[0118] The actuating member 70 is configured such that movement of the actuating member 70 from its rest position to its end-forming position causes movement of the forming punch 60 within the housing 55 from its rest position to its end-forming position.

[0119] By way of example, the actuating member 70 has an elongated shape along a main axis C that is perpendicular to the longitudinal axis B of the housing 55, specifically a substantially vertical axis C, and defines an end section 82. The main axis C extends along a direction F of translation of the actuating member 70. In the illustrated example, the end section 82 comprises a lower end of the actuating member 70.

[0120] By way of example, the facility 50 comprises an opening 72 for receiving the actuating member 70, which is configured to receive an end section 82 of the actuating member 70 when the actuating member 70 moves to its end forming position. In the illustrated example, the receiving opening 72 for the actuating member 70 is formed in the die 53, more particularly in the lower die 100, and optionally extends to the support table 113. A longitudinal end of the forming punch 60 extends into the receiving opening 72.

[0121] More specifically, the device 52 includes an angular drive mechanism 75 configured to convert translational movement of the actuating member 70 along a translation direction F into translation of the forming punch 60 along a movement direction G perpendicular to the translation direction F.

[0122] 9-11, the angular drive mechanism 75 comprises a cam surface 77 formed on the actuating member 70 and a cam following surface 79 formed on the forming punch 60. The cam surface 77 and the cam following surface 79 are configured such that translational movement of the actuating member 70 from the rest position to the end-of-forming position results in sliding contact of the cam surface 77 with the cam following surface 79 and translation of the forming punch 60 from the rest position to the end-of-forming position.

[0123] The actuating member 70 is specifically in the form of a sword-shaped barrel.

[0124] In the illustrated example, the cam following surface 79 is formed on one end of the forming punch 60 .

[0125] 9 to 11, the cam surface 77 is formed by an inclined side surface of the actuating member 70, which side surface forms an angle α with the main axis C of the actuating member 70. The inclined surface is more specifically a flat surface.

[0126] The angle α of the cam surface 77 with the main axis C of the actuating member 70 and the stroke of the actuating member 70 are selected so as to adjust the maximum stroke of the forming punch 60 to the value required to ensure complete forming of the enlarged cross-sectional second portion 59 of the housing 55 and thereby to obtain the desired shape of the enlarged cross-sectional second portion 14 of the semifinished product 11. The angle α is, for example, comprised between 5° and 20°.

[0127] The cam surface 77 and the cam following surface 79 are configured such that movement of the actuating member 70 in translation from the rest position to the end forming position urges the forming punch 60 along the direction G of movement towards the second portion 59 of the housing 55 .

[0128] In a variant, any other type of suitable angular drive mechanism may be used as an alternative to the mechanism described with reference to Figures 9 to 11 .

[0129] 9-11, the device 52 further comprises an elastic return member 85 configured to return the forming punch 60 towards its rest position when the actuating member 70 moves from its end forming position to its rest position. By way of example, the elastic return member 85 comprises a spring arranged around the forming punch 60 and fixedly attached to both the forming punch 60 and the housing 55.

[0130] In the example shown in Figures 9 to 11, the installation 50 further comprises a support 90 to which the actuating member 70 is fastened. In said example, the support 90 is arranged above the housing 55. The actuating member 70 is fastened to a longitudinal end 92 of the support 90 by any suitable means, in particular by bolting or shrink fitting.

[0131] The device or installation 50 is suitable for use as a hydraulic or crankshaft forging press tool. The movement of the press creates a downward vertical movement of the support 90 and the working member 70 which results in shaping to produce the enlarged cross-sectional second portion 14 of the semi-finished product 11.

[0132] The production of a second portion 14 of enlarged cross section of the semi-finished product 11 by hot forging serves to obtain the semi-finished product 11 as previously described.

[0133] As indicated above, the installation 50 further comprises a hot drawing device 54 received in a housing 55 and configured for hot straightening the semi-finished product 11 obtained at the end of the step of producing the second portion 14 of the enlarged cross section.

[0134] The hot drawing device 54 comprises at least one drawing punch 95, which can be seen more specifically in FIG. 10. Preferably, in order to provide a good mechanical balance, the hot drawing device 54 comprises at least two drawing punches 95. The or each drawing punch 95 can be moved in translation relative to the housing 55 from a rest position to a drawing end position along a direction of movement H, the movement of the or each drawing punch 95 from the rest position to the drawing end position resulting in a hot drawing of the semi-finished product 11 to obtain an intermediate part 1. The direction of movement H is perpendicular to the longitudinal axis B of the housing 55, in particular vertical. The direction of movement H runs parallel to the direction of translation F of the working member 70.

[0135] In the illustrated example, the drawing device 54 comprises two drawing punches 95 arranged parallel to each other on either side of the housing 55, only one of the punches 95 being visible in FIG.

[0136] The or each draw punch 95 has an elongated shape and includes end sections 116 along a longitudinal axis E that is perpendicular to the longitudinal axis B of the housing 55 and, more particularly, parallel to the longitudinal axis C of the actuating member 70. In the example shown in the figures, the longitudinal axis E is vertical.

[0137] The die 53 comprises a fixed part and a movable part, the movable part being translationally movable relative to the fixed part along the direction of the longitudinal axis B between a closed position in which the movable part is in contact with the fixed part and a spaced position in which the movable part is spaced apart from the fixed part by an extension distance, the extension distance being selected depending on the degree of stretching desired.

[0138] More specifically, in the example shown in Figures 9 to 11, the fixed portion includes a lower fixed portion 104 included in the lower die 100 and an upper fixed portion 106 included in the upper die 102, and the movable portion includes a downward movable portion 108 included in the lower die 100 and an upward movable portion 110 included in the upper die 102.

[0139] The downwardly movable part 108 and the upwardly movable part 110 are fixed to one another in translation along the direction of the longitudinal axis B. To that end, the downwardly movable part 108 and the upwardly movable part 110 are provided with matching locking reliefs, for example, formed in particular in their facing surfaces.

[0140] Advantageously, the lower fixing portion 104 and the upper fixing portion 106 also comprise matching locking reliefs, in particular formed on their opposing surfaces, which serve to improve their fastening along the direction of the longitudinal axis B of the housing 55.

[0141] Optionally, the fixture 50 comprises a locking portion configured to lock the moving portion of the die 53 to a fixed portion of the die 53 .

[0142] The installation 50 comprises, for example, a guiding device 112 configured to guide the translational movement of a movable part of the die 53 relative to a fixed part of the die 53. The guiding device 112 comprises, for example, a rail 114 provided on the support table 113 and a translational guide member (not shown) formed on the movable part of the die 53, intended to slide on the rail 114. The guide member has a shape that matches the shape of the guide rail 114. By way of example, the guide member has a dovetail shape.

[0143] 11 , the upper die 102 includes, for each draw punch 95, a housing 115 for receiving the draw punch 95 with a shape that matches the shape of an end region 116 of the draw punch 95. The housing 115 for receiving the draw punch 95 is configured to receive the end region 116 of the draw punch 95 as the draw punch 95 moves from its rest position to its end-of-draw position.

[0144] In the illustrated example, each receiving housing 115 is formed at the interface between the fixed and movable portions of die 53, and is partially defined by the movable portion and partially defined by the fixed portion of die 53.

[0145] For example, as shown in FIG. 11, the receiving housings 115 are arranged on both sides of the housing 55 in a direction perpendicular to the direction B of extension of the housing 55 .

[0146] The stretching device 54 is configured such that insertion of the stretching punch 95 into the corresponding receiving housing 115 during movement of the stretching punch 95 from its rest position to its end-of-stretch position results in translational movement of the movable part of the die 53 away from the fixed part of the die 53 along a direction parallel to the longitudinal axis B of the housing 55 by a distance equal to the extension distance.

[0147] In the example shown in Figures 9 to 11, said movement is obtained by a cam effect, the or each drawing punch 95 being provided with a cam surface 117 in its lower area 116 and the or each receiving housing 115 defining a cam follower surface 119 therein. In the example shown in Figures 9 to 11, the cam surface 117 is formed by an inclined side surface of the drawing punch 95, which side surface forms an angle β with the longitudinal axis E of the drawing punch 95. The inclined surface is more particularly a flat surface. The angle β of the cam surface 117 with the longitudinal axis E of the drawing punch 95 and the stroke of the drawing punch 95 are selected to adjust the maximum stroke of the movable part of the die 53 relative to the fixed part to the value required to ensure the desired distortion correction of the semifinished product 11.

[0148] In this example, cam following surface 119 is defined by an inner surface of receiving housing 115 having a shape that matches the shape of a portion of cam surface 117 .

[0149] The cam surface 117 and the cam follower surface 119 are configured such that translational movement of the drawing punch 95 from its rest position to its end-of-draw position urges the movable portion of the die 53 away from the fixed portion along the direction of the longitudinal axis B of the housing 55.

[0150] The translational movement of the movable parts 108, 110 of the die 53 away from the fixed parts 104, 106 of the die 53 results in an extension of the housing 55 along the longitudinal axis B of the housing 55 by a length equal to the extension distance, more specifically, an extension of the central portion 57 of the housing 55. More specifically, the translational movement of the movable parts 108, 110 of the die 53 away from the fixed parts 104, 106 of the die 53 causes the first part 58 of the enlarged cross section and the second part 59 of the enlarged cross section of the housing 55 to move apart. Since the first part 58 of the enlarged cross section and the second part 59 of the enlarged cross section are engaged with the first part 13 of the enlarged cross section and the second part 14 of the enlarged cross section of the semi-finished product 11, the spacing results in a stretching as well as a distortion correction of the semi-finished product 11 received in the housing 55.

[0151] In the example shown in Figures 9 to 11, the or each stretching punch 95 is fixed to the support 90 described above so as to extend opposite the receiving housing 115 along the direction of extension E of the stretching punch 95.

[0152] The support 90 is translationally movable relative to the housing 55 along a direction parallel to the direction of translation F of the actuating member 70 and to the direction of movement H of the or each stretching punch 95 .

[0153] More specifically, the support 90 is positioned in the following positions: a rest position in which the actuating member 70 and each of the drawing punches 95 occupy their rest position; a forming start position in which the actuating member 70 comes into contact with the forming punch 60; a forming end position in which the actuating member 70 occupies its forming end position and has advanced a stroke relative to its rest position resulting in a maximum travel stroke of the forming punch 60; a starting position for hot drawing, at which each drawing punch 95 begins to perform hot drawing; each of the drawing punches 95 occupies its end-of-draw position and has advanced, relative to its rest position, a stroke which results in the desired maximum spacing between the fixed and movable parts of the die 53; is translationally movable relative to the housing 55 to occupy a succession of

[0154] In this example, each stretch punch 95 has a length, measured from the support 90, that is shorter than the length of the actuating member 70, in such a way that each stretch punch 95 brings about the stretching of the semi-finished product 11 by lengthening the housing 55 only after the actuating member 70 has brought about the shaping of the semi-finished part 16 so as to form the enlarged cross-sectional second portion 14. By way of example, the length of the or each stretch punch 95 is adjusted such that the stretch punch 95 reaches the entrance of the corresponding receiving housing 115 when the actuating member 70 reaches its shaping end position.

[0155] As indicated above, the device or installation 50 is suitable for use as a hydraulic forging press tool or crankshaft tool. The movement of the press creates a vertical downward movement of the support 90, which effects shaping to create the second portion 14 of the enlarged area of ​​the semi-finished product 11 as well as an elongation of the semi-finished product 11.

[0156] Now, a method for producing the intermediate part 1 from the semifinished part 16 as previously described, using an installation 50 installed in a forging press, will be explained in more detail.

[0157] The method comprises the following steps: - placing the lower die 100 with the forming punch 60 mounted on the support table 113 and placing the working member 70 and the support 90 with the or each drawing punch 95 mounted thereon; - mounting the blank 16 in the part of the housing 55 defined by the lower die 100; - placing the upper die 102 on the lower die 100; - placing a plunger 103; - lowering the press to press the upper die 102 against the lower die 100 by means of a pusher 103 via the support 90, thereby molding the part of the semi-finished part 16 that is not intended to be molded; - locking the upper die 102 on the lower die 100 after shaping and, optionally, locking of the movable part of the die 53 on the support table 113; - removing the plunger 103; - translating the actuating member 70 from its rest position to its end-of-shaping position by translating the support 90 from its rest position to its end-of-shaping position, so as to form the second portion of enlarged cross-section 14 by hot forging in the second portion of enlarged cross-section 59 of the housing 55 and to obtain the semifinished product 11; - optionally unlocking a movable part of the die 53 to allow it to move in translation relative to a fixed part of the die 53 under the influence of the or each drawing punch 95; - translating the or each drawing punch 95 to its end position by continuing the translational movement of the support 90 to its end position so as to straighten the semifinished product 11 to obtain the intermediate part 1; - raising the support 90, unlocking the upper die 102 and releasing the intermediate part 1; Includes.

[0158] The machine 50 according to the first embodiment and the associated manufacturing method are advantageous. Indeed, the machine 50 allows the production of the enlarged cross-section second portion 14 by hot forging and the straightening of the semifinished product 11 by hot drawing, in direct succession of the method steps, in the same tool. The machine 50 therefore allows the production of a part with the desired straightness characteristics, without the need for intermediate heating between the forming to obtain the enlarged cross-section second portion 14 and the hot drawing. The machine 50 also provides for the production of an intermediate part 1 with a central part whose outer dimensions are close to those of the final part, resulting in material savings and therefore also in manufacturing costs.

[0159] Moreover, in the case of the concrete example shown in figures 9 to 11, the housing 55 extends along a horizontal longitudinal axis B coaxial with the direction of extension of the part to be produced, the housing 55 being formed between a lower die 100 and an upper die 102 which can be moved away from each other substantially perpendicularly to the longitudinal axis B of the housing 55 for the insertion of the blank 6 or semi-finished part 16 or for the withdrawal of the intermediate part 1. Furthermore, the angular drive mechanism 75 serves to convert the vertical movement of the press and thus of the working member 70 into a horizontal movement of the forming punch 60. Such a concrete shape serves to produce very long parts with locally larger cross-sectional areas in a relatively simple and inexpensive manner. Indeed, on the one hand, the insertion of the blank 6 or semi-finished part 16 or the extraction of the intermediate part 1 requires only a relatively small clearance of the upper die 102 relative to the lower die 100, and on the other hand, the overall height of the facility 50 can be relatively small compared to the length of the intermediate part 1 to be produced.

[0160] Furthermore, the definition of the housing 55 between the lower die 100 and the upper die 102, which can be easily moved relative to each other to open the housing 55 through its length, allows for changes in cross-section without problems of retrieving the part after hot forging, which is not the case with conventional tools having die parting planes perpendicular to the longitudinal axis Z of the intermediate part 1 and thus perpendicular to the longitudinal axis B of the housing 55.

[0161] Figures 12 to 14 show an installation 200 for manufacturing an intermediate part 1 according to a second embodiment of the invention. The installation 200 is intended to be used to carry out the manufacturing method described above. The installation 200 more particularly serves to carry out the steps of shaping the blank 6 to obtain a semifinished product 11 and of stretching the semifinished product 11 to obtain the intermediate part 1.

[0162] Only the differences with respect to the installation 50 according to the first embodiment are described below. Furthermore, identical or similar elements are identified by the same reference numerals.

[0163] The installation 200 according to the second embodiment differs from the installation 50 according to the first embodiment mainly by the fact that the device 52 comprises two parallel working members 70 which are fixed in translation relative to each other, the movement of each working member 70 from its rest position to its end-forming position resulting in the production by upsetting, spinning, die forging or backward extrusion techniques of the respective enlarged cross-sectional portions 13, 14 of the semi-finished product 11.

[0164] To that end, the apparatus 200 comprises, for each actuating member 70, an angular drive mechanism 75, a forming punch 60, a housing for receiving the actuating member 70, and an elastic return member 85, as previously described for each actuating member 70.

[0165] The enlarged cross-section first portion 13 and the enlarged cross-section second portion 14 can be made by the same type of hot forging selected from the upsetting technique, the spinning technique, or the back extrusion technique, or by different types of hot forging selected from any combination of said types of hot forging. Preferably, the enlarged cross-section first portion 13 and the enlarged cross-section second portion 14 are made by upsetting or die forging, respectively.

[0166] The shape of the forming punch 60 is selected as a function of the shape of the enlarged cross-sectional portions 13, 14 and the type of hot forging to be performed.

[0167] In this embodiment, as shown in Figures 13 and 14, the housing 55 is intended to receive a blank 6 as previously described.

[0168] The housing 55 has a shape similar to that of the housing 55 described with reference to the first embodiment. However, the housing 55 is provided, at its longitudinal end located at the level of the first portion 58 of the enlarged cross section, with an opening 208 for the insertion of a corresponding forming punch 60 into the housing 55. In such an embodiment, each forming punch 60 is configured to enter the housing 55 at its longitudinal end so as to produce the corresponding portion 13, 14 of the enlarged cross section.

[0169] The enlarged cross-sectional first portion 58 of the housing 55 is configured to accommodate the enlarged cross-sectional first portion 13 of the semi-finished product 11 after it has been formed by hot forging with the forming device 52 in the embodiment.

[0170] In said embodiment, the device 52 serves to produce, with the same tool, and more specifically simultaneously, the first portion 13 of the enlarged cross section and the second portion 14 of the enlarged cross section from the blank 6 received in the housing 55.

[0171] In said embodiment, the hot drawing device 54 is not configured to draw the semifinished product 11 while it is received in the housing 55. The drawing device 54 is not included in the same tool as the device 52 for producing the at least one enlarged cross-sectional portion 14 of the semifinished product 11, as is the case in the first embodiment. In such a case, the drawing device 54 is formed by a separate tool provided for straightening or straightening the shaft by drawing. The drawing device 54 is only indicated diagrammatically in FIG.

[0172] According to a particular embodiment, the further stretching device 54 is similar to the stretching device 54 described with reference to the first embodiment of the installation shown in FIGS.

[0173] In such a case, the drawing device 54 comprises one or more drawing punches and corresponding receiving housings formed in a die as described above, the drawing punches being configured to straighten or straighten by pulling the semi-finished product 11 received in a housing formed between the lower and upper dies in the die, in a manner similar to that described above with respect to the first embodiment. The die and the receiving housings defined by the dies are different from the receiving housings 55 and the die 53 used to shape the blank 6, and more particularly to produce the first portion of the enlarged cross section 13 and the second portion of the enlarged cross section 14.

[0174] In such a case, as described with reference to the first embodiment, the die comprises a fixed part and a movable part, and translational movement of the movable part of the die away from the fixed part over a stroke equal to the extension distance, under the effect of insertion of the drawing punch into the corresponding housing, results in an extension of the housing to receive the semi-finished product 11 by a length equal to the extension distance, thereby resulting in straightening or correcting the distortion of the semi-finished product 11 by pulling.

[0175] Now, a method for producing the intermediate part 1 from the blank 6 as previously described, using the installation 200, will be explained in more detail.

[0176] The method comprises the following steps: - placing a support table 113, then placing the lower die 100 with the forming punch 60 on the support table 113 and placing the support 90 with the actuating member 70; - placing the blank 6 in a portion of the housing 55 defined by the lower die 100; - placing the upper die 102 on the lower die 100; - shaping a part of the blank 6 that is not intended to be shaped, by placing a pusher 103 and pressing the upper die 102 against the lower die 100 with the pusher 103; - locking the upper die 102 to the lower die 100 after forming; - removing the plunger 103; - translating each of the actuating members 70 from its rest position to its end-of-shaping position by translating the support 90 from its rest position to its end-of-shaping position so as to form by hot forging the first enlarged section 13 and the second enlarged section 14 in the first enlarged section 58 and the second enlarged section 59 of the housing 55, respectively, to obtain the semi-finished product 11; - raising the support 90, unlocking the upper die 102 and releasing the semi-finished product 11; - drawing the semi-finished product 11 by means of another drawing device 54 to form an intermediate part 1; Includes.

[0177] The equipment 200 according to the second embodiment and the corresponding manufacturing method allow the first portion 13 of the enlarged cross section and the second portion 14 of the enlarged cross section to be produced in one operation in the same tool by hot forging techniques, in particular by upsetting, spinning or back extrusion techniques, or by any combination of said techniques, resulting in material savings similar to those obtained with the equipment 50 according to the first embodiment, and the central portion 3 of the intermediate part 1 having dimensions very close to those in the final part.

[0178] Furthermore, since the shape of the machine 200 is similar to that of the machine 50, the machine 200 makes it possible to obtain advantages similar to those described above with regard to the possibility of manufacturing long parts. [Explanation of symbols]

[0179] 1 Intermediate parts 3 Central part 4, 4' End of middle part 1 5 First part of the enlarged section 5' The second part of the enlarged section 6 Blank 7 Ring part 11 Semi-finished products, semi-finished parts 12 Central part 13 First part of the enlarged section 14 Second part of the enlarged section 15 Rod part, long part 16 Half-finished part 17 Lost Mandrel 50 Equipment 51 Molding Device 52 Devices 53 Die 54 Hot drawing device 55 Case 57 Central part 58 First part of enlarged section 59 Second part of the enlarged section 60 Forming punch 61 Aperture 62 Rod part 70 Operating member 72 Receiving opening 75 Angle drive mechanism 77 Cam Surface 79 Cam Following Surface 82 Edge area 85 Elastic return member 90 Support 95 Stretching punch 100 Lower Die 102 Upper Die 103 Pusher 104 Lower fixed part 106 Upper fixed part 108 Downward movable part 110 Upwardly movable part 111 Locking System 112 Guidance Device 113 Support Table 114 Guide Rail 115 Case 116 Edge area, lower area 117 Cam Surface 119 Cam Following Surface 120, 121 Locking opening 122 Locking rod 200 equipment 208 Aperture Amin Minimum surface area of ​​the enlarged cross-section of portions 5 and 5' B Longitudinal axis C Principal axis, longitudinal axis D Maximum transverse dimension of central section 3 D1, D2: Maximum dimensions of the cross-section of the enlarged cross-section parts 5 and 5' Maximum cross dimension of edge of Dlog housing 55 Dp Maximum cross-sectional dimension of forming punch 60 E Longitudinal axis, direction of extension F. Direction of translation of the actuating member 70 G Direction of movement H Direction of movement L Overall length, length of intermediate part 1 L0 cumulative length Distance from L1 and L2 ends Z Longitudinal Axis α angle between cam surface 77 and main axis C β angle between cam surface 117 and longitudinal axis E

Claims

1. A method for manufacturing by forging an intermediate part (1) made of a metal alloy, said intermediate part (1) being elongated along a longitudinal axis (Z), said intermediate part (1) comprising a central part (3) with at least one zone of small cross-sectional variation, the cross-sectional surface area of ​​the or each zone of small cross-sectional variation varying by at most 20% along said zone, said intermediate part (1) further comprising a first part (5) of enlarged cross-section and a second part (5') of enlarged cross-section located on either side of said central part (3) along said longitudinal axis (Z), said method further comprising: - manufacturing by hot forging a blank (6) elongated along a longitudinal axis (Z) with at least one area of ​​small cross-sectional variation; shaping the blank (6) to obtain a semi-finished product (11) elongated along the longitudinal axis (Z) with a central portion (12) and a first portion (13) of enlarged cross section and a second portion (14) of enlarged cross section extending on either side of the central portion (12) along the direction of the longitudinal axis (Z), the shaping of the blank (6) comprising the production of the first portion (13) of enlarged cross section of the semi-finished product (11) by hot forging and the production of the second portion (14) of enlarged cross section of the semi-finished product (11) by hot forging selected from the upsetting, spinning, die forging or back extrusion techniques; hot drawing said semi-finished product (11) to obtain said intermediate part (1); The method includes:

2. 2. The method of claim 1, wherein the metal alloy is selected from superalloys, titanium alloys, and steels, more specifically, the steels are selected from the following list: structural hardened steels and alloyed martensitic steels.

3. 3. The method according to claim 1 or 2, wherein the length (L) of the intermediate part (1) is 800 mm or more and the ratio (L / D) between the length (L) of the intermediate part (1) and the maximum transverse dimension (D) of the central portion (3) of the intermediate part (1) is 2.5 or more.

4. 4. A method according to any one of claims 1 to 3, wherein the cross-sectional surface area of ​​the or each area of ​​small cross-sectional change varies by at most 10% along the length of the area, preferably the cross-sectional surface area of ​​the or each area of ​​small cross-sectional change is constant along the area.

5. 5. The method according to claim 1, wherein the cumulative length (L0) of at least one of the zones of small cross-sectional changes along the longitudinal axis (Z) is equal to or greater than 40% of the length (L) of the intermediate part (1), preferably equal to or greater than 60% of the length (L) of the intermediate part (1), and even more preferably equal to or greater than 70% of the length (L) of the intermediate part (1).

6. 6. The method according to claim 1, wherein the center of the first portion (5) of the enlarged cross-section and / or the center of the second portion (5') of the enlarged cross-section along the longitudinal direction (Z) of the intermediate part (1) is positioned at a distance (L1, L2) of the corresponding ends (4, 4') of the intermediate part (1) that is not more than 25% of the length (L) of the intermediate part (1), preferably not more than 15% of the length (L) of the intermediate part (1).

7. 7. The method according to any one of claims 1 to 6, wherein the first portion (13) of enlarged cross section of the semi-finished product (11) is produced by upsetting, spinning, die forging or back extrusion.

8. 8. The method according to any one of claims 1 to 7, wherein the second portion (14) of the enlarged cross section of the semifinished product (11) is produced by upsetting, and preferably the first portion of the enlarged cross section is produced by upsetting or die forging.

9. 9. The method according to claim 1, wherein the production of the first portion (13) of the enlarged cross section of the semifinished product (11) and the production of the second portion (14) of the enlarged cross section of the semifinished product (11) are carried out successively.

10. 9. The method according to claim 1, wherein the production of the first portion (13) of the enlarged cross section of the semifinished product (11) and the production of the second portion (14) of the enlarged cross section of the semifinished product (11) are carried out simultaneously, more particularly on the same tool.

11. 11. The method according to claim 1, wherein the semi-finished product (11) is not reheated between producing the second portion (14) of enlarged cross section of the semi-finished product (11) and the hot drawing.

12. 12. The method according to any one of claims 1 to 11, wherein the production of the second portion (14) of enlarged cross section and the hot drawing are carried out in the same tool.

13. 1. A method for manufacturing an elongated part made from a metal alloy, comprising the steps of: Manufacturing an intermediate part (1) using a method according to any one of claims 1 to 12, finishing said intermediate part (1) to obtain said part, said finishing comprising more particularly machining; The method includes:

14. 14. The method according to claim 13, wherein the parts are selected from axles, drive shafts, parts for landing gear, riser pipes for pumps intended for oil or gas extraction, underwater valves, in particular for engines for large ships such as liners or supertankers, and missile launchers.

15. An installation (50; 200) for the production by forging of an intermediate part (1) made of a metal alloy part, said intermediate part (1) being elongated along a longitudinal axis, said production installation (50; 200) being intended to be used for the implementation of a method according to any one of claims 1 to 12, a housing (55) defining a longitudinal axis (B) intended to receive an elongated blank (6) along the longitudinal axis (Z), said blank (6) comprising at least one area of ​​small cross-sectional variation or semi-finished part (16) elongated along the longitudinal axis (Z), said semi-finished part (16) comprising a rod portion (15) comprising at least one area of ​​small cross-sectional variation and a first part (13) of an enlarged cut surface; a forming device (51) for forming the blank (6) or the semi-finished part (16) received in the housing (55) so as to form an elongated semi-finished product (11) along a longitudinal axis (Z) having a central portion (12) and a first portion (13) of enlarged cross section and a second portion (14) of enlarged cross section located on either side of the central portion (12) along the direction of the longitudinal axis (Z), the forming device (51) comprising a device (52) for producing at least the second portion (14) of enlarged cross section of the semi-finished product (11) by hot forging through die forging, upsetting, spinning or back extrusion; a hot stretching device (54) configured to hot-relieve the semi-finished product (11) to form the intermediate part (1); Facilities equipped with (50; 200).

16. Installation (50; 200) according to claim 15, wherein the device (52) for producing at least the second portion (14) of the enlarged cross section of the semifinished product (11) comprises at least one actuating member (70) which is translationally movable relative to the housing (55) along a direction perpendicular to the longitudinal axis (B) of the housing (55) from a rest position to an end-forming position, the movement of the actuating member (70) from its rest position to its end-forming position resulting in the production by hot forging of at least the second portion (14) of the enlarged cross section of the semifinished product (11).

17. 17. An installation (200) according to claim 16, wherein the device (52) for producing at least the second portion (14) of the enlarged cross-section of the semifinished product (11) comprises two actuating members (70) each movable in translation relative to the casing (55) along a direction perpendicular to the longitudinal axis (B) of the casing (55) from a rest position to an end-forming position, the actuating members (70) being fixed in translation relative to one another in a direction perpendicular to the longitudinal axis (B) of the casing (55), and the movement of each actuating member (70) from its rest position to its end-forming position results in production by hot forging of a respective portion (13, 14) of the enlarged cross-section of the semifinished product (11).

18. The device (52) for producing at least the second portion (14) of the enlarged cross section of the semifinished product (11) comprises: a forming punch (60) for each actuating member (70), each configured to move in translation along the direction of the longitudinal axis (B) of the housing (55); an angular drive mechanism (75) configured to convert the movement of the or each working member (70) from its rest position to its forming end position into a translational movement of the corresponding forming punch (60) along the direction of the longitudinal axis (B) of the housing (55) in order to produce by hot forging the corresponding portion of the enlarged cross section (13, 14) of the semi-finished product (11); 18. Installation (50; 200) according to claim 16 or 17, comprising:

19. 19. The installation (50) according to any one of claims 15 to 18, wherein the hot stretching device (54) is configured for hot relieving the semi-finished product (11) received in the housing (55).

20. 20. The installation (50) according to claim 19, wherein the hot drawing device (54) comprises a drawing punch (95) which is translationally movable relative to the housing (55) along a direction perpendicular to the longitudinal axis (B) of the housing (55) from a rest position to a drawing end position, the movement of the drawing punch (95) from the rest position to the drawing end position resulting in hot straightening of the semi-finished product (11) received in the housing (55) to obtain the intermediate part (1).

21. the installation (50) comprises a die (53) defining the housing (55), the die (53) comprising fixed parts (104, 106) and movable parts (108, 110), the movable parts (108, 110) of the die (53) being movable in translation relative to the fixed parts (104, 106) in the direction of the longitudinal axis (B) of the housing (55) between a closed position in which the movable parts (108, 110) are in contact with the fixed parts (104, 106) and a spaced position in which the movable parts (108, 110) are spaced apart from the fixed parts (104, 106) by an extension distance, the movement resulting in an extension of the housing (55) by a length equal to the extension distance, 21. The installation (50) according to claim 19 or 20, wherein the hot drawing device (54) further comprises, for each drawing punch (95), a receiving housing (115) for the drawing punch (95) configured to receive an end region (116) of the drawing punch (95) when the drawing punch (95) moves from its rest position to its end-drawing position, and wherein insertion of the drawing punch (95) into the corresponding receiving housing (115) moves the movable parts (108, 110) of the die (53) in translation relative to the fixed parts (104, 106) of the die (53) from the closed position to the spaced position so as to straighten the semi-finished product (11) received in the housing (55).

22. The installation (50) further comprises a support (90) to which the or each actuating member (70) and the or each drawing punch (95) (95) are fastened, the support (90) being arranged in the following positions: a rest position in which the or each operating member (70) and the or each drawing punch (95) occupy their said rest position; a forming end position in which the or each operating member (70) is in its forming end position; a stretch end position in which the or each stretch punch (95) is in its stretch end position; 22. The installation (50) according to claim 20 or 21 in combination with any one of claims 15 to 17, wherein the installation (50) is translationally movable relative to the housing (55) along a direction parallel to the direction of movement of the or each actuating member (70) and to the direction of movement of the or each drawing punch (95) so as to occupy successively

23. 23. The installation (50) according to any one of claims 15 to 22, for use as a forging press tool.

24. Use of an installation (50) according to any one of claims 15 to 22 as a forging press tool.

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