Tooling for localized heat treatment of a mechanically welded component and associated method for relieving welding stresses by means of this tooling
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2026-02-05
- Publication Date
- 2026-08-13
Smart Images
Figure FR2026050113_13082026_PF_FP_ABST
Abstract
Description
DESCRIPTION Localized heat treatment tooling for a welded mechanical part and associated process for relaxing welding stresses using this tooling. TECHNICAL FIELD OF THE INVENTION
[0001] The present invention relates to a localized heat treatment tooling that allows for stabilizing and relieving the welding stresses of a welded mechanical part.
[0002] It also relates to a process for relaxing the welding stresses of a welded mechanical part by a localized post-weld heat treatment, applied using this tooling. TECHNOLOGICAL BACKGROUND OF THE INVENTION
[0003] Stabilizing welding stresses is a crucial issue in the production of welded mechanical parts. Indeed, during welding, significant thermal stresses occur in the weld zone due to the rapid heating and cooling of the materials, which induces successive, rapid, and uneven expansion and contraction throughout the part.
[0004] This results in permanent internal stresses that remain in the material after cooling. These residual stresses can significantly impact weld quality and durability. They weaken the part, increase the risk of cracking or distortion, and can lead to failures. It is therefore crucial to stabilize these stresses after welding to eliminate residual internal stresses.
[0005] This is typically achieved through post-weld heat treatment, during which the part to be treated is placed in a furnace to undergo a controlled thermal cycle. It is first slowly heated to a specific temperature, for example, around 700°C for certain steel parts, and then held there for a sufficient time to allow the metal to relax through a creep mechanism, enabling it to stabilize by distributing internal stresses more evenly. The part is then cooled slowly and in a controlled manner to prevent the formation of new stresses.
[0006] While such post-weld heat treatment is effective in stabilizing welding stresses, it nevertheless has disadvantages.
[0007] Indeed, such a furnace treatment requires significant resources, especially when the parts to be treated are large, as is very often the case in the aerospace industry, for example. This treatment is lengthy and expensive due to the large size of the furnace required for heating and the bulky holding tools needed inside it, and it demands substantial logistics and resources. The overall profitability of the part manufacturing process is consequently reduced.
[0008] Therefore, there is a need for a new post-weld treatment process that would stabilize welding stresses just as effectively, but without these drawbacks.
[0009] There is also a need for new tooling that would allow for the easy implementation of this new process. SUMMARY OF THE INVENTION
[0010] The invention aims to meet these needs by providing localized heat treatment tooling to stabilize the welding stresses of a welded mechanical part.
[0011] To this end, a first aspect of the invention teaches a tool for localized heat treatment of a metal part comprising a weld bead to be relaxed.
[0012] This tooling includes a stirrup, which is an angled support structure, comprising a fixed jaw, a movable jaw and a guide assembly, the movable jaw being mounted to move away from and towards the fixed jaw by being guided by the guide assembly.
[0013] The fixed jaw and the movable jaw each comprise a pad and a clamping element, the two pads being mounted opposite each other and movable towards or away from each other, and being pushed towards each other by their respective clamping element when said clamping element is actuated.
[0014] In addition, each skate is equipped with a support plate and a heating element that heats the support plate, the two support plates being arranged opposite each other.
[0015] This tooling advantageously allows for localized heat treatment, without oven use, of a metal part in order to relax / stabilize the welding stresses of this part which are accumulated in the area around the weld bead, without impacting the rest of the part.
[0016] It allows for precise positioning and ensures good rigidity during operation. It is mechanically and thermally resistant, economical, and does not risk damaging the metal part. Furthermore, it is easy for the operator to use, as it is ergonomic and easy to handle. In addition, its small size makes it lightweight and portable.
[0017] The clamp with its two jaws holds the entire tooling assembly securely in place on the workpiece and ensures rigidity, much like a clamp. Furthermore, thanks to the movable jaw's movement, the tooling can be easily positioned and precisely placed on the workpiece without difficulty for the operator, and then easily removed once the machining is complete.
[0018] The pads allow the support plates to be positioned against the metal part and pressed against the area to be treated by pressing on it in the manner of a vise, the pressing force being generated by the clamping element.
[0019] The support plates transmit the heat produced by the heating elements and allow this heat to be diffused by conduction towards the area being treated against which they rest. Heat exchange is optimal due to their surface contact with this area; their thinness gives them a degree of flexibility that allows them to adapt to the shape of the part, achieving near-perfect surface contact.
[0020] Advantageously, the pads and support plates can be made of, for example, Inconel. Tm which is a material perfectly suited to high temperatures and can therefore withstand a temperature of approximately 700°C for several hours.
[0021] Advantageously, the pads can preferably be manufactured by electro-erosion to give them the exact complementary shape of the area to be treated on the metal part. They can thus perfectly conform to the curves of the area to be treated when pressed against it by the clamping elements and achieve near-perfect surface contact without risk of damage.
[0022] Advantageously, the guide assembly can be a set of two parallel rods along which the movable jaw slides.
[0023] The movable jaw can thus be easily moved closer to or further from the fixed jaw, without jamming or becoming slanted, along the parallel rods, which can for example extend inside parallel cylindrical bores of the movable jaw.
[0024] Advantageously, the guide assembly can in this case include stop elements at the free end of the parallel rods which prevent the movable jaw from coming out.
[0025] The locking elements prevent the movable jaw from being pulled out of the tooling, thus avoiding its loss when the tooling is not in use. All tooling components are therefore held together, even when the tooling is not in use.
[0026] These locking elements are, for example, nuts screwed onto the ends of parallel rods. In this case, they can advantageously be removed if necessary in order to remove the movable jaw.
[0027] Advantageously, the clamping element can be a clamping screw, preferably with a knurled head, comprising a threaded rod, which passes through a tapped bore of the corresponding jaw and opens out of said tapped bore in the direction of the corresponding pad.
[0028] It is therefore very easy and quick to push the pads closer together by simply tightening the clamping screw. Indeed, when tightened, the shank of the clamping screw moves longitudinally inside the bore and its free end comes to rest against the corresponding pad, which it pushes towards the other pad as the screw continues to tighten.
[0029] Actuating the clamping screw in the opposite direction (unscrewing) causes a translation in the opposite direction of its stem in the tapped bore of the jaw, which releases the pad and allows it to be moved just as easily away from the other pad.
[0030] The head of the screw may advantageously have a shape or relief that improves gripping, for example a knurled head, to facilitate manual screwing.
[0031] Advantageously, each of the pads can be mounted on the corresponding jaw by means of two preferably welded posts which slide in bores of said jaw.
[0032] The two pads are thus simply assembled, each on one of the jaws, while remaining mobile relative to them, so as to be able to move away from or towards them depending on whether they are pushed or not by the clamping element, by means of a simple sliding of the columns in these bores.
[0033] Advantageously, the heating element can be an electrical resistor placed between the pad and the support plate. The support plate can thus be heated simply and efficiently by conduction. It can, in turn, locally heat the metal workpiece against which it rests in the area where the weld bead to be relaxed is located.
[0034] The use of a heating element also allows for a slow and regular temperature rise, a maintenance of temperature when the heating plateau is reached, and then a similarly slow and regular temperature fall.
[0035] Advantageously, the support plates can be equipped with at least one temperature sensor. This sensor allows for monitoring the temperature at the support plates and regulating the operation of the heating elements to reach and maintain the desired temperature for localized heat treatment, as well as controlling the temperature rise and fall. The operating temperature can thus be measured in real time.
[0036] Advantageously, each of the support plates can include at least two grooves in which thermocouples are mounted. These thermocouples allow the desired temperature measurements to be carried out in a simple, economical and efficient manner within the high temperature ranges (from 500 to 800°C) targeted by the invention.
[0037] Furthermore, by arranging the grooves differently on each of the plates, it is possible to obtain a localized temperature measurement at different locations on these heating plates.
[0038] Advantageously, the support plates can be mounted on the skates by means of two elastic side tabs.
[0039] The support plates can thus be held onto the skates by snapping them together, which allows them to be easily detached and reattached for replacement if needed.
[0040] Furthermore, these flexible side tabs also allow, depending on their length, for the support plates to be mounted in a floating manner on their respective pads. This allows them to move slightly to perfectly adapt to the shape of the metal part against which they are placed.
[0041] A second aspect of the invention relates to a localized heat treatment process for a metal part comprising a weld bead to be relaxed, which comprises the following steps: provision of tools as described above; moving the movable jaw away from the fixed jaw, positioning the tooling on the metal part by engaging the metal part between the fixed and movable jaws, and moving the movable jaw towards the fixed jaw, the tooling being positioned on the metal part so that the weld bead is opposite at least one of the support plates after the movable jaw is brought closer together; actuating the clamping element of each jaw to push the two pads towards each other, until the support plates are in contact with the metal part and cover the weld bead to be relaxed, activation of the heating element of each of the pads and heating of the support plates.
[0042] Such a process advantageously allows for heat treatment of the metal part which is only localized in the area of the part which contains the weld bead to be relaxed.
[0043] After the two pads are brought together, the surface on which the weld bead is located is advantageously sandwiched between the two support plates. The surface is therefore heated from both sides simultaneously when the support plates heat up. Thus, the heat treatment of the weld bead is homogeneous on all sides, as if the entire part were placed in an oven. The heat treatment is optimal, even if it remains localized.
[0044] This process allows for weld stabilization / stress relief without having to place the entire workpiece, often very large, in a furnace. The savings in time, energy, and handling are considerable, for a comparable result.
[0045] In addition, such a process, without oven treatment, avoids having to subject parts of the part that do not need additional heating, while the number of complete heat treatments that the part is allowed to undergo during its manufacturing cycle is also limited (to three in general) to avoid the appearance of possible defects or non-conformities.
[0046] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES
[0047] The figure below is presented as an illustration and in no way limits the invention.
[0048] [Fig. 1] is a general perspective view of an example of tooling according to the invention.
[0049] [Fig. 2] is seen in perspective of a portion of a metal flange with a weld bead to be relaxed.
[0050] [Fig. 3] is seen in perspective of the portion of the metal flange in Figure 2 on which the tooling in Figure 1 has been placed.
[0051] [Fig. 4] and [Fig. 5] are cross-sectional views of the portion of the metal flange in Figure 2 on which the tooling of Figure 1 has been placed, this tooling being shown respectively before and after the actuation of the clamping elements.
[0052] [Fig. 6] and [Fig. 7] are perspective views of two examples of a support plate shown alone. DETAILED DESCRIPTION
[0053] By convention in this application, the terms "top", "bottom", "upper", "lower", "above", "below", "horizontal" and "vertical" will be defined according to the orientation adopted by the elements in the figures, this orientation not necessarily being retained by these elements in use.
[0054] Figure 1 shows an example of tooling 1 according to the invention.
[0055] This tooling 1 includes a caliper 2 comprising two jaws 3, one fixed jaw 4 and one movable jaw 5, joined by a guide assembly 6.
[0056] In mechanics, a stirrup is a bent (or swan-neck) part, preferably made of metal, designed to support or join other parts. The assembly formed by the two jaws 3 and the guide assembly 6 constitutes a stirrup.
[0057] The fixed jaw 4 is located in the upper part of the tooling 1 and has a curved shape with a cross-section substantially in an inverted U (or swan neck), with a first portion 7 substantially vertical corresponding to a first branch of the U, and a second portion 8 inclined corresponding to the second branch of the U.
[0058] Two rods 9, preferably cylindrical and parallel, start from the first portion 7 of the fixed jaw 4 and extend substantially vertically below it, in order to constitute the guide assembly 6.
[0059] The movable jaw 5 has two cylindrical and through bores 10 through which the rods 9 are engaged. It can thus slide along the rods 9, and therefore move closer to or further away from the fixed jaw 4 by being guided along these rods without risk of being put at an angle.
[0060] When it is at the bottom of the rods 9, the movable jaw 5 is very far away from the fixed jaw 4. In this position, called the engagement position, it is very easy for the operator to engage a metal part 11 to be treated between the two jaws 3. Similarly, it is easy for him to remove the tooling 1 from this metal part 11 once the heat treatment is finished.
[0061] On the contrary, when the movable jaw 5 is at the top of the rods 9, it is in contact with the first portion 7 of the fixed jaw 4 and is opposite the second portion 8 of the fixed jaw 4 in a position called the treatment position.
[0062] To prevent the rods 9 from being unintentionally withdrawn from the bores 10 of the movable jaw 5, stop elements 12 are provided at the free lower end of the rods 9 against which the movable jaw 5 abuts at the end of its travel. The movable jaw 5 therefore cannot be unintentionally removed from the bracket 2 and risk being lost.
[0063] In the example shown, these stop elements 12 are advantageously assemblies: nut 13 plus washer 14, which have the advantage of being economical and removable in order to allow the assembly of the movable jaw 5 and its removal if desired.
[0064] A pad 15 is mounted on each of the jaws 3 in such a position that these pads 15 are opposite each other when the movable jaw 5 is in the treatment position. A first pad 15 is thus placed on the inner face of the second portion 8 of the fixed jaw 4, and the second pad 15 is placed on the inner face opposite the movable jaw 5.
[0065] These pads 15 are essentially rectangular pieces, but not necessarily flat; advantageously, they have a shape complementary to that of the portion of the metal part 11 against which they are intended to bear. In the example shown, the pads 15 thus have a curved shape and are complementary to each other.
[0066] These pads 15 have on their rear face two preferably welded columns 16, which extend substantially perpendicularly to their wall 17 and are engaged in two cylindrical bores 18 of the jaw 3 on which they are mounted. The pads 15 are thus able to move closer to or further from each other by sliding their columns 16 within these bores 18 of the jaws 3.
[0067] Each of the jaws 3 also includes a clamping element 19, namely a clamping screw 20 in the example shown, which allows the corresponding pad 15 to be pushed in the direction of the other pad 15 when it is actuated.
[0068] The clamping screw 20 has a head 21, which is located on the outside of the corresponding jaw 3, and a threaded rod 22 which passes through a tapped bore 23 of the jaw 3 and whose free end 24 emerges out of this tapped bore 23 in the direction of the corresponding pad 15.
[0069] Thus, the operator can easily grasp the head 21, which is knurled for example, and turn the tightening screw 20 in the tightening or loosening direction. The threaded rod 22 then moves longitudinally in the tapped bore 23, its free end 24 protruding more or less outside this bore.
[0070] When this movement is continued in the direction of screwing, the free end 24 comes to rest against the corresponding pad 15, as illustrated in Figure 4, and then pushes it towards the other pad 15, as illustrated in Figure 5.
[0071] On the contrary, if the operator turns the head 21 in the unscrewing direction, the free end 24 moves away from the pad 15, which can be pushed away from the other pad 15.
[0072] Tooling 1 also includes two support plates 25 which are mounted opposite each other, one on each of the pads 15, and which are arranged for this purpose on the inner face of each of the pads 15.
[0073] These support plates 25, shown alone in figures 6 and 7, are preferably flat rectangular pieces, behind which extend two lateral tabs 26 ending in a hook return 27 which allow the support plate 25 to be hooked onto the corresponding pad 15, thanks to an elastic deformation of these lateral tabs 26.
[0074] Advantageously, these support plates 25 have grooves 28 in which temperature sensors 29, for example thermocouples 30, can be housed in order to control the temperature of the support plates 25 and the treated portion of the metal part 11.
[0075] These grooves 28 can be of any number and arranged according to any suitable distribution which is not necessarily identical on the two support plates 25. In the embodiment shown, for example there are four of them, two per support plate 25, and they are arranged horizontally on one of the support plates 25 (figure 6) and vertically on the other support plate 25 (figure 7).
[0076] Each of the pads 15 is also equipped with a heating element 31 (visible in Figures 4 and 5), for example an electrical resistor 32, which heats the corresponding support plate 25. This heating element is preferably interposed between the pad 15 and the support plate 25, and can, for example, be housed in a recess in the pad 15 as in the example shown.
[0077] An example of the application of tooling 1 and the localized heat treatment process that can be implemented with this tooling 1 has been shown in figures 2 to 5.
[0078] In many technological fields and in particular in the field of aeronautics, one frequently encounters metal parts 11 with annular flange 33 as partially represented in figure 2. This is for example a part intended to be assembled around a shaft and / or with it and often a rotating part.
[0079] This metal part 11 has a through-hole 35 in its wall 34, around which a weld bead 36 has been formed on both sides of the wall 34. This weld bead 36 is small, for example, about 15 mm in diameter, and stress relief around this weld bead 36 conventionally requires heating the entire metal part 11 in a furnace. Thanks to the tooling 1 and the localized heat treatment process according to the invention, only the area around and in the immediate vicinity of the weld bead 36 will be heated.
[0080] For this, the tooling 1 is placed in the engagement position with the movable jaw 5 separated from the fixed jaw 4, then is placed on the metal part 11, the wall 34 of the annular flange 33 being engaged between the jaws 3.
[0081] The tooling 1 is positioned by the operator so that the weld bead 36 is covered by the support plate 25 of the fixed jaw 4, as illustrated in Figure 3.
[0082] The movable jaw 5 is then raised against the first portion 7 of the fixed jaw 4, in the treatment position, as illustrated in figures 3 and 4. The two pads 15 are then opposite each other, but separated from each other on each side of the wall 34.
[0083] The operator then turns the clamping screws 20 in the screwing direction in order to push, with the free end 24 of these screws 20, the pads 15 closer together, until the two support plates 25 are in contact with the wall 34 and cover the weld bead 36 as illustrated in Figure 5.
[0084] The tightening movement of the clamping screws 20 can advantageously be continued until a satisfactory tightening of the pads 15 is obtained, guaranteeing perfect surface support of the support plates 25 against the wall 34.
[0085] The tooling is then firmly mounted on the metal part 11 to be treated. However, since the pads 15 are of a curved shape adapted to that of the wall 34, there is no risk of marking or damaging it.
[0086] The localized heat treatment can then begin. For this, the heating elements 31 are switched on to heat the support plates 25 gradually and evenly, then maintain them at a suitable holding temperature for the heat treatment of the weld bead 36 for several hours (at 700°C, for example). The heat from these support plates 25 is efficiently transferred by conduction to the wall 34 against which they are pressed, locally throughout the entire area surrounding the weld bead 36.
[0087] Once the heat treatment is complete, the temperature of the support plates 25 is gradually reduced by appropriate control of the heating elements 31, to obtain slow and regular cooling of the weld bead 36.
[0088] The temperature rise of the support plates 25, their maintenance at a plateau temperature, and then their progressive cooling are advantageously controlled by means of the temperature sensors 29.
[0089] Once the tooling 1 and the wall 34 have cooled, the clamping screws 20 are unscrewed, the pads 15 are moved apart and the movable jaw 5 is lowered into the engagement position away from the fixed jaw 4. The tooling 1 can then be easily removed from the metal part 11.
Claims
DEMANDS
1. Tooling (1) for the localized heat treatment of a metal part (11) comprising a weld bead (36) to be stress-relieved, characterized in that: - the tooling (1) includes a stirrup (2), which is an angled support structure, comprising a fixed jaw (4), a movable jaw (5) and a guide assembly (6), the movable jaw (5) being mounted to move away from and towards the fixed jaw (4) by being guided by the guide assembly (6); - in that the fixed jaw (4) and the movable jaw (5) each comprise a pad (15) and a clamping element (19), the two pads (15) being mounted opposite each other and movable towards or away from each other, and being pushed towards each other by their respective clamping element (19) when said clamping element (19) is actuated; and - in that each of the skates (15) is equipped with a support plate (25) and a heating element (31) which heats the support plate (25), the two support plates (25) being arranged opposite each other.
2. Tooling (1) according to claim 1 characterized in that the guide assembly (6) is a set of two parallel rods (9), along which the movable jaw (5) slides. [Claims] Tooling (1) according to claim 2 characterized in that the guide assembly (6) comprises stop elements (12) at the free end of the parallel rods (9) which prevent the exit of the movable jaw (5).
4. Tooling (1) according to any one of the preceding claims characterized in that the clamping element (19) is a clamping screw (20) comprising a threaded rod (22), which passes through a tapped bore (23) of the corresponding jaw (3) and emerges out of said tapped bore (23) in the direction of the corresponding pad (15). [Claims] Tooling (1) according to any one of the preceding claims characterized in that each of the pads (15) is mounted on the corresponding jaw (3) by means of two columns (16) which slide in bores (18) of said jaw (3). [Claims] Tooling (1) according to any one of the preceding claims characterized in that the heating element (31) is an electrical resistance (32) interposed between the pad (15) and the support plate (25).
7. Tooling (1) according to any one of the preceding claims characterized in that the support plates (25) are mounted on the pads (15) by means of two elastic lateral tabs (26). [Claims] Tooling (1) according to any one of the preceding claims characterized in that the support plates (25) are equipped with at least one temperature sensor (29). [Claims] Tooling (1) according to any one of the preceding claims characterized in that each of the support plates (25) comprises at least two grooves (28) in which thermocouples (30) are mounted.
10. A localized heat treatment method for a metal part (11) comprising a weld bead (36) to be stress-relieved, characterized in that it comprises the following steps: - supply of a tool (1) according to one of the preceding claims; - movement of the movable jaw (5) away from the fixed jaw (4), placement of the tool (1) on the metal part (11) by engaging the metal part (11) between the fixed jaw (4) and the movable jaw (5), and movement of the movable jaw (5) towards the fixed jaw (4), the tool (1) being placed on the metal part (11) so that the weld bead (36) is opposite at least one of the support plates (25) after the movable jaw (5) is brought closer; - actuation of the clamping element (19) of each of the jaws (3) in order to push the two pads (15) together until the support plates (25) are in contact with the metal part (11) and cover the weld bead (36) to be relaxed,- activation of the heating element (31) of each of the pads (15) and heating of the support plates (25).