FR3025121A1 - FOLDING DEVICE AND METHOD FOR FORMING CORRUGATION IN AN ANGLE PIECE - Google Patents

Abstract

The invention relates to a folding device for forming a corrugation in a corner piece (1) comprising: - a lower frame (24); a central matrix element (26) corresponding to the shape of a central portion of the corrugation; two lateral matrix elements (27) capable of defining an imprint corresponding to the shape of a first and a second end portion of the corrugation; - an upper frame (25) movable vertically; - A central punch (40) adapted to engage inside the cavity of the central die element (26) during the movement of the upper frame (25) to its folding position; - two movable assemblies (41, 42) each having two flanks (43, 44), a punch-knife (45, 53); and a cam surface (57) adapted to cooperate with a cam follower (58) carried by the lower frame (24) so as to move the movable assemblies to a close position upon movement of the upper frame (25) to its position folding.

Description

TECHNICAL FIELD The invention relates to a device and a folding method for forming a corrugation in a corner piece for the construction of a sealing membrane of a fluid storage tank.

The invention relates in particular to the field of tanks, waterproof and thermally insulating, with membranes, for the storage and / or transport of fluid, such as a cryogenic fluid. BACKGROUND ART In the state of the art, and in particular in document FR 2861060, corrugated metal membranes are known for forming sealing barriers for liquefied natural gas storage tanks. The sealing membrane consists of a plurality of metal plates having a series of perpendicular corrugations allowing it to deform under the effect of thermal and mechanical stresses generated by the fluid stored in the tank. At the junction between two walls of the metal membrane, the metal membrane has corner pieces that ensure the continuity of the sealing of the metal membrane and are flexible to ensure the flexibility of the membrane at the level of the corner area.

Such a corner piece has two flanges inclined relative to each other and joining at an edge and has a corrugation extending from one end to the other of the corner piece of so as to allow a deformation of the corner piece in a transverse direction parallel to the edge. Summary An idea underlying the invention is to provide a device and a folding method, simple and reliable, for forming a corrugation in a corner piece for the construction of a waterproofing membrane. According to one embodiment, the invention provides a folding device for forming a corrugation in a corner piece having first and second plane flanges inclined with respect to each other and meeting at the same level. 3025121 2 d an edge, the corrugation to be formed being intended to protrude inwardly from the corner piece and to extend in a longitudinal direction secant to the edge, from one end to the other of the piece of angle so as to allow a deformation of the corner piece in a transverse direction, parallel to the edge, the corrugation to be formed having a first end portion and a second end portion respectively disposed on the first flange and on the second wing and a central portion overlapping the edge and extending between the first and second end portions in the extension of said first and second end portions, the end portions each having, at the end a corner of a meeting zone with the central portion, a recess such that the central portion of the corrugation penetrates within the first and second end portions; the folding device comprising: - a lower frame; a central matrix element, mounted on the lower frame, having an imprint, extending in a longitudinal direction, corresponding to the shape of the central portion of the corrugation; two lateral matrix elements, carried by the lower frame and arranged on either side of the central matrix element, the two lateral matrix elements each comprising a first and a second bearing surface intended respectively to receive an inner surface of the first and second wings of the corner piece, said first and second bearing surfaces of each of the side die members being inclined relative to each other about an axis of horizontal edge corresponding to the edge of the corner piece when the first and second wings of the corner piece are received against the first and second bearing surfaces, the two lateral matrix elements each having a half a recess extending in the longitudinal direction and having a first and a second portion respectively bordering the first and second bearing surfaces of said lateral die member; the first and second portions of the half-indents of the two lateral elements being respectively able to define an imprint corresponding to the shape of the first and second end portions of the corrugation; - A movable upper frame, in a vertical direction secant to the edge axis, relative to the lower frame, between a rest position and a folding position; A central punch, carried by the upper frame, disposed opposite the central die element and having a shape complementary to the impression of said central die element, said central punch being adapted to engaging the imprint of the central die member to form the central portion of the corrugation upon movement of the upper frame from its home position to its folded position; two mobile assemblies slidably mounted on the upper frame between a close position and a spaced apart position, the two moving assemblies being respectively disposed opposite the first bearing surfaces and the second bearing surfaces of the two lateral elements and each being movable in a longitudinal direction parallel to said first or second bearing surfaces facing each other, each of the moving assemblies comprising: - two clamps each having a clamping surface extending respectively parallel and in with respect to either of the first or second bearing surfaces so as to clamp the corner piece against the bearing surfaces of the die side members, when the upper frame is in its folding position; and - a knife-punch disposed opposite the half-impressions of the die side members, said punch-punch having a shape corresponding to the shape of the first or second end portions of the corrugation and being adapted to engage within the first or second portions of the half-indentations of the two side matrix members when the upper frame is in its folding position to form the first or second end portion of the corrugation, said knife punch comprising a main portion and two knives intended to be positioned on either side of the central punch when the moving assemblies are in their close position; a cam surface adapted to cooperate with a cam follower carried by the lower frame, when the upper frame moves towards its folding position, the cam surface and the cam follower being arranged so that the assembly mobile is moved from its remote position to its close position during the movement of the upper frame to its folding position.

According to embodiments, such a folding device may comprise one or more of the following features: the cam follower carried by the lower frame is an idle roller. the movable assemblies each comprise a carriage slidably mounted on a guide rail carried by the upper frame. the carriage or the guide rail comprises a plurality of rolling bodies capable of cooperating with raceways carried by the guide rail or the associated carriage. the mobile assemblies each comprise a support and the clamps of each mobile assembly are associated with the support of said moving assembly and slidably mounted on the associated support in a direction orthogonal to the first or second bearing surfaces facing said mobile assembly, said clamps being remotely removed from the support of said movable assembly by return members. The flanks are slidably mounted on the associated support via guide tubes carried by the flanks and sliding in bores in the associated support. the return members are compression springs or gas cylinders exerting a return force between the clamps and the associated support. The lateral matrix elements are slidably mounted on the lower frame in a direction transverse between a spaced position and a close position, the first and second portions of the longitudinal half-cavities of the two lateral matrix elements being respectively able to define a corresponding imprint in the shape of the first and the second end portions of the corrugations when the matrix side members are in their close position. the die side members each comprise a cam surface adapted to cooperate with an associated cam follower carried by the upper frame, the cam surfaces and the cam followers being arranged such that said die side members are moved from one another; their position remote to their close position during the movement of the upper frame to its folding position. The cam followers are idler rollers carried by the upper frame. the die side members are moved from their remote position to their near position by means of one or more pneumatic cylinders. the pneumatic cylinder is associated with a position sensor capable of delivering a signal representative of the position of the upper frame between its rest position and its folding position so as to allow control of the movement of the pneumatic cylinder as a function of the position of the frame 10 higher. the lateral matrix elements each comprise a carriage slidably mounted on an associated guide rail carried by the lower frame. According to one embodiment, the invention also relates to a folding device for forming a corrugation in a metal sheet intended for the construction of a sealed membrane of a fluid storage tank, the folding device comprising: lower frame; a first and a second lateral matrix element each having a bearing surface of the metal sheet and a concave half-cavity, the first and second lateral matrix elements being each slidably mounted on the lower frame, in a transverse direction the longitudinal direction of the corrugation to be slidably formed between a spaced position and a close position, the half-impressions of the first and second matrix side members together defining an imprint corresponding to the shape of the corrugation to be formed when the first and second die side members are in their close position, said first and second die side members being biased toward their spaced apart position by a biasing member; and one or more punches, arranged above the lateral matrix elements having a shape complementary to that of the cavity, said punch (s) being movable vertically with respect to the lower frame between a rest position and a position of bending wherein the head of said upper punch is engaged within the indent defined by the die side members so as to press the metal sheet; said first and second die side members being arranged such that they move from their spaced apart position to their close position as the punch moves from its home position to its fold position. According to one embodiment, the invention also provides a folding method for forming a corrugation in a corner piece by means of a bending device mentioned above, said corner piece having first and second inclined flat wings 10 relative to one another and joining at an edge, the undulation to be formed being intended to protrude inwardly from the corner piece and to extend in a longitudinal direction secant to the edge, from one end to the other of the corner piece so as to allow a deformation of the corner piece in a transverse direction, parallel to the edge, the corrugation to be formed comprising a first extreme portion and a second end portion respectively disposed on the first wing and the second wing and a central portion overlapping the edge and extending between the first and second end portions in the extension of said first and second extreme portions, the extreme portions each having, at a meeting point with the central portion, a recess such that the central portion of the corrugation penetrates within the first and second end portions; said folding method comprising: positioning the corner piece so that the first and second wings of the corner piece are respectively in abutment against the first and second bearing surfaces of the two lateral elements of matrix; and - moving the upper frame from its rest position to its folding position. Some aspects of the invention are based on the idea of providing a simple folding device which does not require specific actuation means for the punch knives. Certain aspects of the invention start from the idea of proposing a method and a folding device making it possible to obtain a corrugation without modifying the thickness of the sheet. Some aspects of the invention are based on the idea of providing a simple folding device that does not require specific actuation means for moving the die side members. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood, and other objects, details, features and advantages thereof will become more apparent in the following description of several particular embodiments of the invention, given only in connection with the invention. illustrative and non-limiting, with reference to the accompanying drawings. - Figure 1 is a sectional view of a sealed and thermally insulating tank for storing a fluid at a corner area between two walls. Figure 2 is a perspective view of a corner piece. - Figure 3 is a view of a corrugated metal plate for the construction of a sealed membrane of a storage tank of a fluid. FIGS. 4, 5 and 6 illustrate a folding device intended for the formation of a corrugation in a corner piece, respectively in a high resting position, an intermediate position of contact with the corner piece and a folding position, at the end of the race. - Figures 7, 11 and 15 are front views of the folding device respectively in its upper position of rest, in its intermediate position of contact with the corner piece and in its folding position, end of stroke. FIGS. 8, 12 and 16 are side views of the folding device respectively in its high rest position, in its intermediate position of contact with the corner piece and in its folding position, at the end of the stroke. FIGS. 9, 13 and 17 are views in section respectively along the planes IX-IX, XIII-XIII and XVII-XVII of FIGS. 8, 12 and 16. FIGS. 10, 14 and 18 are sectional views respectively according to plans XX, XIV-XIV and XVIII-XVIII of Figures 7, 11 and 15. - Figure 19 is a partial perspective view of the folding device illustrating the central punch, knife punches and the central element of matrix . - Figure 20 is a sectional view of a folding device according to another embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS The folding device and the associated folding method, which will be described later, are intended for the production of a corner piece 1 for the construction of a waterproofing membrane. a sealed and thermally insulating tank. By way of example, FIG. 1 illustrates the structure of a sealed and thermally insulating tank equipped with such a corner piece 1, at an angle formed between two walls 2, 3 of the tank. Each wall 2, 3 of the tank comprises, from the outside to the inside of the tank, a carrier structure 4, a secondary thermal insulation barrier 5 comprising insulation blocks 6 retained against the supporting structure 4 and anchored thereto by secondary retaining members 7, a secondary sealing membrane 8 carried by the insulating blocks 6 of the secondary thermal insulation barrier 5, a primary thermal insulation barrier 9 comprising blocks of secondary insulation 10, anchored to the secondary waterproofing membrane 8 by primary retaining members, not shown, and a primary sealing membrane 11, carried by the insulation blocks 10 of the primary thermal insulation barrier 9 and intended to be in contact with the cryogenic fluid contained in the tank. The primary waterproofing membrane 11 has a plurality of corrugated metal plates 12, as shown in Fig. 3, welded to each other. Each metal plate 12 comprises a first series of parallel corrugations 13, said low, extending in a direction y and a second series of parallel corrugations 14, said high, extending in a direction x. The x and y directions of the wave series 13, 14 are perpendicular. The corrugations 13, 14 are projecting on the side of the inner face of the metal plate 12, intended to be placed in contact with the fluid contained in the tank. The edges of the metal plate are here parallel to the corrugations 13, 14. At the angle formed between the two adjacent walls 2, 3 of the tank, the primary waterproofing membrane 11 comprises a corner piece 1, illustrated in detail in Figure 2. The corner piece 1 is obtained by folding a metal sheet. It is preferably made of a material identical to that of corrugated metal plates 12. The metal sheet may in particular be made of stainless steel, aluminum, Invar C: that is to say an alloy of iron and nickel whose expansion coefficient is typically between 1.2 × 10 -6 and 2 × 10 -6 K -1, or in an iron alloy with a high manganese content whose expansion coefficient is of the order of 7 × 10 -6. K-1. However, other metals or alloys are also possible. For example, the metal sheet has a thickness of about 1.2 mm. Other thicknesses are also possible, knowing that a thickening of the sheet metal causes an increase in its cost and generally increases the rigidity of the corrugations.

The corner piece 1 has first and second flanges 15, 16 inclined relative to each other and joining at an edge 17. The projecting angle formed between the two flanges 15, 16 is of the order of 105 ° in the embodiment shown. However, in general, the angle formed between the two wings 15, 16 may be between 90 ° inclusive and 180 ° excluded. Each wing 15, 16 has a rectangular parallelepipedal shape and thus comprises two opposite parallel lateral edges 18, 19 and an end edge 20, opposite to the other wing 15, 16. The corner piece 1 comprises a ripple 21 giving it flexibility to deform under the effect of thermal and mechanical stresses generated by the liquefied natural gas stored in the tank. The corrugation 21 extends in a longitudinal direction, secant at the edge 17, from one end to the other of the corner piece 1. The corrugation 21 thus extends parallel to the opposite lateral edges 18, 19, 16. The corrugation 21 thus allows the corner piece 1 to deform in a transverse direction, parallel to the edge 17. As the corrugations 13, 14 of the metal plates, the corrugation 21 protrudes from the inside of the corner piece 1, ie towards the inside of the projecting angle formed between the two wings 15, 16 of the corner piece 1. Thus, the corrugation 21 protrudes into the vessel when the corner piece 1 is placed within the vessel.

As shown in FIG. 1, the corner piece 1 is arranged in such a way that its corrugation 21 is in the extension of the corrugation 14 of the adjacent metal plates 12, of the one and the other of the walls 2. , 3. The corner piece 1 is connected to the adjacent metal plates 12, by welding, to ensure a continuity of sealing at the corner area.

Returning to FIG. 2, it can be observed that the corrugation 21 can be divided into three portions, a first end portion 21a formed in the first flange 15 and a second end portion 21b formed in the second flange 16. and a central portion 21c overlapping the ridge 17 and extending between the first and the second end portions 21a, 21b in the extension thereof. The first end portion 21a extends from the free edge 20 of the first flange 15 towards the edge 17. Symmetrically, the second end portion 21b extends from the free edge 20 of the second flange 16 in the direction of the ridge 17. The first and second end portions 21a, 21b have a substantially semi-elliptical or triangular profile. The central portion 21c of the corrugation overlaps the edge 17 and extends between the two wings 15, 16, in the extension of the first and second end portions 21a, 21b. The central portion 21c also has a profile of substantially semielliptical or triangular shape. The end portions 21a, 21b present at their meeting zone with the central portion 21c a recess 22 so that the central portion 21c penetrates inside the end portions 21a, 21b of the corrugation. Moreover, the end portions 21a, 21b of the corrugation extend on either side of the central portion 21b, to the vicinity of the edge 17.

A device 23 and a folding method for forming such a corrugation 21 in a corner piece 1 will now be described in connection with FIGS. 4 to 20. By convention, the "longitudinal" orientation of the folding device 23 is directed in the longitudinal direction of the corrugation 21 to be formed and the "transverse" orientation is directed transversely to the longitudinal direction 25 of the corrugation 21 to be formed. In a first step, a metal sheet is folded beforehand so as to form two plane wings 15, 16 inclined with respect to each other. Subsequently, a corrugation 21 is formed in the corner piece 1 by means of the folding device 23, as described below.

The folding device 23 comprises a lower frame 24 and an upper frame 25 mounted vertically movable relative to the lower frame 24. The upper frame 25 is movable between a high rest position and a bending position of the sheet in which it it is deformed to form the corrugation 21. The upper frame 3025121 11 25 is thus able to exert on the corner piece 1 a pressure allowing the folding of the metal sheet and the formation of the corrugation 21. The upper frame 25 is illustrated in its rest position in FIGS. 4 and 7 to 10 and in its folded position in FIGS. 6 and 15 to 18. The upper frame 25 is also shown in an intermediate position of contact with the workpiece. angle 1, just before the formation of the corrugation 21 begins, in Figures 5 and 11 to 14. As shown, for example in Figure 10, the lower frame 24 supports a central element of matrix 26. The elem The central die 26 has a recess extending in the longitudinal direction of the corrugation to be formed 21. The recess has a shape corresponding to the shape of the central portion 21c of the corrugation 21 and is thus intended to receive a portion of the corner piece 1 straddling the two wings 15, 16. Furthermore, the lower frame 24 also supports two lateral matrix elements 27, 28 disposed on either side of the central die element 26. The side matrix members 27, 28 are slidably mounted on the lower frame 24 in a transverse horizontal direction between a spaced apart position shown in Fig. 10 and a close position shown in Fig. 18. To do this , as shown in FIG. 7, each lateral matrix element 27, 28 comprises two carriages 29, 30 which are each slidably mounted on an associated guide rail 31, 32, carried by the infill frame 24. The carriages 29, 30 are advantageously rolling carriages which comprise a plurality of rolling bodies capable of cooperating with raceways carried by the associated guide rail 31, 32. Alternatively, it is also possible to provide guide rails 31, 32 having rolling bodies capable of cooperating with bearing tracks carried by the associated carriage 29, 30. Return members, such as springs or gas cylinders, not shown, provide a return two lateral matrix members 27, 28 towards their spaced apart position. As shown for example in FIGS. 7 and 9, each lateral matrix element 27, 28 has first and second bearing surfaces 33, 34 of the corner piece 1, inclined with respect to the another of an angle corresponding to the angle formed between the two wings 15, 16 of the corner piece 1. Thus, the first bearing surfaces 33 are intended to receive the inner surface of the first wing 15 of the piece 1 and the second bearing surfaces 24 are intended to receive the inner surface of the second flange 16 of the corner piece 1. Moreover, as shown in Figure 10, each side element 27 of matrix 27 , 28 has at its edge vis-à-vis the other lateral element of matrix 27, 28 a concave half-foot 35, extending in the longitudinal direction of the corrugation 21 to form. The concave half-cavity 35 may be divided into two portions, namely a first portion extending along the edge of the first bearing surface 33 and extending in the longitudinal direction parallel to the first bearing surface 33 and a second portion extending along the edge of the second bearing surface 34 and extending in the longitudinal direction parallel to the second bearing surface 34. When the die side members 27, 28 are in a In the close-up position, the first portions of the concave halfprints 35 of the lateral matrix elements 27, 28 together form an imprint corresponding to the shape of the first end portion 21a of the corrugation 21 and the second portions of the concave half impressions 35 of the Lateral matrix elements 27, 28 together form an imprint corresponding to the shape of the second end portion 21b of the corrugation 21. As illustrated in FIGS. and 18, each side matrix member 27, 28 has at its outer edge, opposite to the other side die member 27, 28, a member having a cam surface 36 adapted to cooperate with a cam follower 37 carried by the upper frame 25, when the upper frame 25 moves from its rest position to its folding position. The cam follower 37 is here a roller 38 mounted idly about a horizontal axis, 25 extending in the longitudinal direction. The roller 38 is carried by a vertical arm 39 secured to the upper frame 25 and extend towards the lower frame 24. The use of such a roller 38 limits the friction forces exerted between the surface of the The cam surface 36 is oriented such that when the upper frame 25 moves from its resting position to its folding position, the cam follower 37 exerts a bearing on the surface. cam member 36 tending to move the respective die side element 27, 28 to its close position.

In an alternative embodiment, shown in FIG. 20, the displacement of the matrix side members 27, 28 from their remote position to their close position is not provided by the cam surface 36 and the cam follower 37. but by one or more pneumatic cylinders 59. The pneumatic jack 599 has a first end 60 attached to one of the die side members 28 and a second end 61 attached to the other die side member 27. Thus, when the pneumatic cylinder 59 extends, the matrix side members 27, 28 deviate from each other to their remote position whereas when the pneumatic cylinder 59 is shortened, the lateral matrix elements 27, 28 are brought closer together from each other to their close position. In the embodiment shown, the pneumatic cylinder 59 passes through bores formed in the lateral matrix elements 27, 28 (The passage of the pneumatic cylinder through the lateral elements is not shown, the axis of the cylinder being symbolized in dashed lines).

Furthermore, the pneumatic cylinder (s) 59 is associated with a position sensor 62 arranged to deliver a signal representative of the position of the upper frame 25 between its rest position and its folding position and allowing thus controlling the movement of the pneumatic cylinder 59 as a function of the position of the upper frame 25 so as to coordinate the movement of the side matrix members 27, 28 with the movement of the upper frame 25. Furthermore, the folding device 23 comprises a central punch 40, particularly shown in Figures 10, 14 and 18, carried by the upper frame 25. The central punch 40 extends vis-à-vis the central die element 26 and has a shape complementary to the footprint of said central die element 26. The central punch 40 has a V-shaped cross-section elongating in the longitudinal direction. Thus, when the upper frame 25 moves towards its folding position, the central punch 40 engages inside the cavity of the central die element 26 so as to form the central portion 21c of the corrugation 21. The folding device 23 further comprises two movable assemblies 41, 42 mounted horizontally sliding in the longitudinal direction on the upper frame 25 between a spaced apart position, visible in FIGS. 7 and 9, and a position close, visible in Figures 15 and 17. Return members, such as springs, not shown, provide a return of the two movable assemblies 41, 42 to their spaced position.

A first movable assembly 41 is disposed vis-à-vis the first bearing surfaces 33 of the matrix side members 27, 28 and a second movable assembly 42 is disposed opposite the second bearing surfaces 34 of the lateral matrix elements 27, 28.

Each movable assembly 41, 42 comprises two clamps 43, 44, particularly shown in FIGS. 8 and 10, for clamping the corner piece 1 against the bearing surfaces 33, 34 facing each other, during the folding operation, and a knife-punch 45, 53, in particular represented in FIG. 9, making it possible to form one or the other of the end portions 21a, 21b of the corrugation 21.

Each mobile assembly 41, 42 comprises a support 46 equipped with a pair of carriages 47, 48 which are each slidably mounted on a guide rail 49, 50, carried by the upper frame 25. The carriages 47, 48 or rails for guiding 49, 50 advantageously comprise a plurality of rolling bodies capable of cooperating with raceways carried by the guide rail 49, 50 or the carriage 47, associated with it. The mobile assemblies 41, 42 are slidably mounted relative to the upper frame 25, in a longitudinal orientation, parallel to the bearing surfaces 33, 34 vis-à-vis the lateral matrix elements 27, 28. Moreover, each assembly mobile 41, 42 comprises a first flange-clamp 43 having a clamping surface arranged parallel to and opposite a bearing surface 33, 34 of one of the lateral matrix elements 28 and a second clamp flank 44 having a clamping surface arranged parallel and vis-a-vis 33, 34 of a bearing surface of the other of the matrix side members 27. Thus, the flanks 43, 44 are able to plate the wings 15, 16 of the corner piece 1 against the bearing surfaces 33, 34 of the lateral matrix elements 27, 28 when the upper frame 25 is in its folding position. The flanks 43, 44 are movably mounted on the support 46 in a direction orthogonal to their clamping surface, via a guiding device. The guiding device comprises, for each strut holder 43, 44, two guide tubes 51, carried by the strut holder 43, 44 and oriented orthogonally to the clamping surface of said strut holder 43, 44 and sliding to the Bore interior formed in the support 46. Furthermore, a plurality of compression springs 52 exert an elastic force between the support 46 and each flange clamp 43, 44. To do this, the compression springs 52 each comprise a first end end housed inside a blind hole formed in the support 46 and a second end housed inside a blind hole in the flange clamp 43, 44. According to an alternative embodiment not shown the compression springs 52 can be replaced by gas cylinders.

The knife punch 45 of the first movable assembly 41 is disposed opposite the first half-cavity portions of the die side members 27, 28 and the knife punch 53 of the second movable assembly is disposed in a screw-in manner. second half-cavity portions of the lateral matrix elements 27, 28. Thus, when the upper frame 25 is moved from its rest position to its folding position, the knife punches 45, 53 engage to the indentations formed by the lateral matrix elements 27, 28 so as to form the end portions 21a, 21b of the corrugation 21. As illustrated in particular in FIG. 19, the knife punches 45, 53 comprise a main portion 54 and two knives 55, 56. The main portion 54 has a V-shaped section having a shape complementary to the impression vis-à-vis the lateral matrix elements 27, 28. The two knives 55, 56 are able to come to positi onner or other of the central punch 40 when the movable assemblies 41, 42 are in their close position. The knives 45, 53 thus allow the formation of the extensions of the end portions 21a, 21b of the corrugation 21 on either side of the central portion 21c. With reference to FIGS. 9, 13 and 17, it can be seen that each moving assembly 41, 42 comprises a cam surface 57 adapted to cooperate with a cam follower 58 carried by the lower frame 24, when the upper frame 25 moves from its rest position to its folding position (see FIGS. 13 and 17). The cam follower 58 here is a idler roller mounted about a horizontal axis, extending in the transverse direction. The cam surface 57 is oriented such that when the upper frame 25 moves from its rest position to its bending position, the cam follower 58 exerts a rest on the cam surface 57 tending to move the assembly together. mobile 41, 42 to its close position. In the illustrated embodiment, the cam followers 58 are disposed on either side of the two die side members 27, 28 in the longitudinal plane of the corrugation to be formed and the cam surface 57 is fixed. on the moving assembly, in the plane of knife punches 45,53.

The folding method will now be described in detail. In a first step, a metal sheet is previously bent to form a corner piece 1 having two flanges 15, 16 inclined relative to each other around an edge 17.

Subsequently, the corner piece 1 thus produced is positioned against the bearing surfaces 33, 34 of the matrix side members 27, 28 (see FIGS. 4 and 7 to 10). The projecting angle of the corner piece 1 is directed towards the lower frame 24 so that the inner surfaces of the flanges 15, 16 rest against the bearing surfaces 33, 34 of the matrix side members 27, 28.

When the corner piece 1 has been correctly positioned, the upper frame 25 is moved downward from its rest position, illustrated in FIGS. 4 and 7 to 10. As the upper frame 25 moves towards its end position, the flanks 43, 44 come to press the wings 15, 16 of the corner piece 1 against the bearing surfaces 33, 34 of the lateral matrix elements 27, 28.

Then, the central punch 40 engages inside the imprint of the central die element 26 to form the central portion 21c of the corrugation 21 and the knife punches 45, 53 engage to the indentations formed by the lateral matrix members 27, 28 to form the end portions 21a, 21b of the corrugation 21.

At the same time, the cam followers 37 carried by the upper frame 25 contact the cam surfaces 36 carried by the die side members 27, 28 so as to displace the die side members 27, 28 towards their cam members. close position. Thus, the displacement of the matrix side members 27, 28 towards their close position simultaneously with the formation of the corrugation 21 makes it possible to ensure that there is little or no change in the thickness of the metal sheet. when folding. It is indeed important that the metal sheet has a constant thickness so as not to degrade its mechanical properties. On the other hand, the cam followers 58 carried by the lower frame 24 come against the cam surfaces 57 carried by the moving assemblies 41, 42. Thus, the knife punches 45, 53 come closer to each other, at the same time as they move towards the lower frame 24, so as to form the extensions of the end portions 21a, 21b of the corrugation 21 on either side of the central portion 21c and 3025121 17 to form the recesses 22 so that the central portion 21c of the corrugation 21 penetrates inside the end portions 21a, 21b. Although the invention has been described in connection with several particular embodiments, it is quite obvious that it is in no way limited thereto and that it includes all the technical equivalents of the means described as well as their combinations if these These are within the scope of the invention. The use of the verb "to include", "to understand" or "to include" and its conjugated forms does not exclude the presence of other elements or steps other than those set out in a claim. The use of the indefinite article "a" or "one" for an element or a step does not exclude, unless otherwise stated, the presence of a plurality of such elements or steps. In the claims, any reference sign in parentheses can not be interpreted as a limitation of the claim.

Claims (14)

REVENDICATIONS1. Folding device (23) for forming a corrugation (21) in a corner piece (1) having first and second planar flanges (15, 16) inclined relative to one another and joining one another at an angle a ridge (17), the corrugation (21) to be formed being intended to protrude towards the inside of the corner piece (1) and to extend in a longitudinal direction secant to the edge (17). ), from one end to the other of the corner piece (1) so as to allow a deformation of the corner piece (1) in a transverse direction, parallel to the edge (17), the corrugation (21) to be formed comprising a first end portion (21a) and a second end portion (21b) respectively disposed on the first flange (15) and the second flange (16) and a central portion (21c) overlapping the edge (17) and extending between the first and second end portions (21a, 21b) in the extension of said first and second end portions (21a, 21b), the end portions (21a, 21b) each having, at a meeting zone with the central portion (21c), a recess (22) so that the central portion (21c) of the corrugation (21) penetrates within the first and second end portions (21a, 21b); the folding device (23) comprising: - a lower frame (24); - a central die element (26), mounted on the lower frame (24), having a recess, extending in a longitudinal direction, corresponding to the shape of the central portion (21c) of the corrugation (21); two lateral matrix elements (27, 28), carried by the lower frame (24) and arranged on either side of the central matrix element (26), the two lateral matrix elements (27, 28) each having first and second bearing surfaces (33, 34) for respectively receiving an inner surface of the first and second wings (15, 16) of the corner piece (1), said first and second bearing surfaces (33, 34) of each of the die side members (27, 28) being inclined relative to each other about a horizontal edge axis corresponding to the edge (17) of the corner piece (1) when the first and second flanges (15, 16) of the corner piece (1) are received against the first and second bearing surfaces (33, 34), the two side members of matrix (27, 28) each having a half-cavity (35) extending in the longitudinal direction and having a first and a second porti the first and the second bearing surfaces (33, 34) of said lateral matrix element (27, 28) are bordered respectively, the first and second portions of the half-cavities (35) of the two lateral elements being respectively able to defining an imprint corresponding to the shape of the first and second end portions (21a, 21b) of the corrugation (21); - an upper frame (25) movable in a vertical direction secant to the edge axis, relative to the lower frame (24), between a rest position and a folding position; a central punch (40) carried by the upper frame (25) disposed opposite the central die element (26) and having a shape complementary to the impression of said central die element ( 26), said central punch (40) being able to engage inside the cavity of the central die element (26) to form the central portion (21c) of the corrugation (21) when the movement of the upper frame (25) from its rest position to its folding position; Two movable assemblies (41, 42) slidably mounted on the upper frame (25) between a close position and a spaced position, the two movable assemblies (41, 42) being respectively disposed opposite the first surfaces of the support (33) and second bearing surfaces (34) of the two lateral matrix members (27, 28) and each being movable in a longitudinal direction parallel to said first or second bearing surfaces (33, 34) in vis-à-vis, each of the movable assemblies (41, 42) comprising: - two flanks (43, 44) each having a clamping surface extending respectively parallel and in relation to the one and the other of the first or second bearing surfaces (33,34) so as to clamp the corner piece (1) against the bearing surfaces (33,34) of the die side members (28) when the upper frame (25) is in its folding position; and - a knife-punch (45, 53) disposed opposite the half-cavities (35) of the die side members (27, 28), said knife-punch (45, 53) having a corresponding shape in the shape of the first or second end portions (21a, 21b) of the corrugation (21) and being able to engage inside the first or second portions of the half-indentations (35) of the two elements die side (27, 28) when the upper frame (25) is in its folding position to form the first or the second end portion (21a, 21b) of the corrugation (21), said knife punch (45) having a main portion (54) and two knives (55, 56) intended to be positioned on either side of the central punch (40) when the movable assemblies (41, 42) are in their close position ; - a cam surface (57) adapted to cooperate with a cam follower (58) carried by the lower frame (24), when the upper frame (25) moves towards its folding position, the cam surface (57) and the cam follower (58) being arranged such that the moving assembly (41, 42) is moved from its remote position to its close position upon movement of the upper frame (25) toward its folding position. Folding device (23) according to claim 1, wherein the cam follower (58) carried by the lower frame is an idle roller. 15 3. folding device (23) according to claim 1 or 2, wherein the movable assemblies (41, 42) each comprise a carriage (47, 48) slidably mounted on a guide rail (49, 50) carried by the frame higher (25). Folding device (23) according to claim 3, wherein the carriage (47, 48) or the guide rail (49, 50) comprises a plurality of rolling bodies adapted to cooperate with raceways carried by the guide rail (49, 50) or the carriage (47, 48) associated therewith. Folding device (23) according to any one of claims 1 to 4, wherein the movable assemblies (41, 42) each comprise a support (46) and in which the flanks (43, 44) of each mobile assembly (41, 42) are associated with the support (46) of said movable assembly (41, 42) and slidably mounted on the associated support (46) in a direction orthogonal to the first or second bearing surfaces (33, 34) opposite said moving assembly (41, 42), said flanks (43, 44) being biased away from the support (46) of said moving assembly (46) by return members (52). 30 6. Folding device (23) according to claim 5, wherein the flanks (43, 44) are slidably mounted on the associated support (46) via guide tubes (51) carried by the clamps (43, 44) and sliding in bores in the associated support (46). 3025121 21 7. Folding device (23) according to claim 5 or 6, wherein the return members (52) are compression springs or gas cylinders exerting a return force between the flanks (43, 44) and the associated support (46). 8. Folding device (23) according to any one of claims 1 to 7, wherein the lateral matrix elements (27, 28) are slidably mounted on the lower frame (24) in a transverse direction between a remote position and a close position, the first and second portions of the longitudinal half-impressions (5) of the two lateral matrix elements (27, 28) being respectively able to define an imprint corresponding to the shape of the first and the second extreme portions (21a, 21b) corrugations (21) when the die side members (27, 28) are in their close position. The folding device (23) according to claim 8, wherein the die side members (27,28) each have a cam surface (36) engageable with a cam follower (37) associated with the cam follower (37). upper frame (38), the cam surfaces (36) and the cam followers (37) being arranged such that said matrix side members (27,28) are moved from their remote position to their close position during movement from the upper frame (25) to its folding position. 20 The folding device (23) according to claim 9, wherein the cam followers (37) are idle rollers (38) carried by the upper frame (25). The folding device (23) according to claim 8, wherein the die side members (27,28) are moved from their remote position to their close position by means of one or more pneumatic cylinders. 25 12. Folding device (23) according to claim 11, wherein the pneumatic cylinder is associated with a position sensor capable of delivering a signal representative of the position of the upper frame (25) between its rest position and its folding position. so as to allow control of the movement of the pneumatic cylinder as a function of the position of the upper frame (25). 30 Folding device (23) according to any one of claims 8 to 12, wherein the lateral matrix elements (27, 28) each comprise a carriage (29, 30) slidably mounted on a guide rail (31, 32) associated carried by the lower frame (24). 3025121 22 14. Folding method for forming a corrugation (21) in a corner piece (1) by means of a folding device (23) according to any one of claims 1 to 13, said corner piece (1) ) having first and second plane flanges inclined relative to each other and joining at an edge (17), the corrugation (21) to be formed being intended to protrude inwards of the corner piece (1) and to extend in a longitudinal direction secant to the edge (17), from one end to the other of the corner piece (1) so as to allow deformation of the corner piece (1) in a transverse direction, parallel to the edge (17), the undulation (21) to be formed comprising a first end portion (21a) and a second end portion (21b) arranged respectively on the first wing (15) and on the second wing (16) and a central portion (21c) overlapping the edge (17) and extending between the first and the second extreme portion (21a, 21b) in the extension of said first and second end portions (21a, 21b), the end portions (21a, 21b) each having, at a meeting zone with the central portion (21c), a recess (22) such that the central portion (21c) of the corrugation (21) enters the interior of the first and second end portions (21a, 21b); said folding method comprising: - positioning the corner piece (1) so that the first and second flanges (15, 16) of the corner piece (1) bear respectively against the first and second flanges (15, 16) of the corner piece (1) the second bearing surfaces (33, 34) of the two lateral die members (27, 28); and - moving the upper frame (25) from its rest position to its folding position.