WO2008138763A1

WO2008138763A1 - Connection framework at an inner corner meeting point between two vertical structure formwork panels

Info

Publication number: WO2008138763A1
Application number: PCT/EP2008/055337
Authority: WO
Inventors: Pedro Xammar Bove
Original assignee: Inveral, S.A.
Priority date: 2007-05-09
Filing date: 2008-04-30
Publication date: 2008-11-20

Abstract

The invention relates to a connection framework (1) at an inner corner meeting point between two vertical structure formwork panels. The framework comprises two rigid frames joined at one of their sides, each provided with a planar main face (2,2'), provided on their sides with an edging (3) provided with coupling means (4), said frames being joined such that the respective planar main faces form in a formworking position an inner corner with an approximately 90° angle. The framework comprises a flexible central corner connection element (5) connecting the two rigid frames along their entire length, the cross section of the mentioned central element generally being at a right angle, and a regulation system by means of which the inner angle forming the main faces of the rigid frames in a formworking position can be varied, being able to adopt an angle considerably less than 90° in a stripped position by deforming the flexible central element, thus facilitating the separation of the framework from the concrete surface of the 90° inner corner.

Description

D E S C R I P T I O N

"Connection framework at an inner corner meeting point between two vertical structure formwork panels"

Technical Field of the Invention

The invention relates to a connection framework at the inner corner meeting point at a right angle between two vertical structure formwork panels, such as those used for forming the inner corner meeting points between two sides or walls for ex- ample.

The connection framework comprises two rigid frames each provided with an essentially planar main face, provided on their sides with an edging provided with coupling means for coupling to the formwork panel adjacent to the frame, said rigid frames being joined such that the respective planar main faces form in a formwork- ing position an inner corner with an angle of approximately 90^Q.

Background of the Invention

The use of formwork panels for forming vertical concrete structures is well- known, for example, for a two-sided wall, two rows of formwork panels with their respective formworking surfaces opposite one another and separated by a distance that is equivalent to the projected thickness for said wall are usually arranged in parallel.

Due to the increasing variety of architectural designs, a wide range of form- working frameworks for building curved polygonal walls as well as for forming the inner or outer meeting points of walls either in a right, acute or obtuse corner have been developed. Therefore, in order to form obtuse-angle inner corners nowadays there are connection frameworks formed by two rigid frames provided with respective formworking faces hingedly connected to one another along a common vertical shaft, which shaft will define the corner line at the meeting point between the con- crete surfaces formed by the mentioned formworking faces. Depending on the angle projected for the corner, the connection framework will open more or less in order to adopt said angle and said position will then be mechanically fixed so that while the concrete is poured, the angle between the formworking faces will not undergo any variations due to the pressure exerted by the concrete. Once the vertical structure to which the concrete has been poured has been stripped, the arris of the resulting corner must be manually finished due to the rounded and rough shape it usually has due to the hinged shaft of the connection framework.

Despite new designs, the meeting points of walls in 90^Q inner corners con- tinue to be the most common. To form said corners, corner connection frameworks are used which are formed by an element with a right angle cross section provided with respective formworking faces on each flank, or corner connection frameworks are used which are formed by two frames fixedly joined at a right angle the respective formworking faces of which form the surfaces of the corner meeting point. Obvi- ously right corner connection frameworks are provided on their edges with coupling means for their linkage with the adjacent formwork panels of the rest of the wall.

Unlike with angled inner corners, the finishing of the 90^Q inner corner arrises formed with the right angle connection frameworks is favorable and no manual repair operations are required. Nevertheless, the mentioned right angle connection frameworks present problems when the formwork is stripped due to the resistance of the formworking faces of the framework to detach from the concrete surface of the wall. For this reason, when the formwork is stripped from an inner corner section of a wall it is necessary to couple the framework to a crane so that the crane can pull on it for the purpose of separating it from the right-angle inner corner, which slows down the process and increases the costs associated to same.

The need therefore exists for a connection framework for inner corner meeting points providing correct formation and finishing of the mentioned sections and which at the same time is easy to strip from the vertical concrete structure.

Description of the Invention

For the purpose of providing a solution to the problems set forth, a connection framework at an inner corner meeting point between two vertical structure formwork panels is provided. The connection framework comprises two rigid frames joined at one of their sides, each provided with an essentially planar main face, pro- vided on their sides with an edging provided with coupling means for coupling to an adjacent formwork panel, said frames being joined such that the respective planar main faces form in a formworking position an inner corner with an angle of approximately 90^Q.

Essentially, the connection framework is characterized in that it comprises a flexible central corner connection element connecting the two rigid frames along their whole length, the cross section of the mentioned central element generally being at a right angle, and a regulation system by means of which the inner angle formed by the main faces of the rigid frames in a formworking position can be var- ied, being able to adopt in a stripped position an angle considerably less than 90^Q by deforming the flexible central element, thus facilitating the separation of the framework from the concrete surface of the 90^Q inner corner.

According to another feature of the invention, the regulation system comprises at least one tensioning device the ends of which are joined to the edging of the sides of the rigid frames, in such a way that when the tensioning device is operated, its ends exert a tractive force on the mentioned sides, progressively reducing the inner angle between the main faces of the mentioned rigid frames.

According to another feature of the invention, the tensioning device can be manually operated and is formed by an axial element provided with two externally threaded ends, one with a right-hand thread and the other with a left-hand thread, each of said threaded ends being coupled in the complementarily threaded perforation of a corresponding end tubular element, each end tubular element being joined at its other end to the edging of the side of a corresponding rigid frame of the framework. According to another feature of the invention, the flexible central element has an L-shaped cross section, being provided with two flanges.

According to another feature of the invention, the regulation system comprises two pairs of essentially planar, rectangular trapezoid-shaped end ribs which are separated from one another, transversely arranged in the longitudinal ends of the framework like a cover, each end rib of one and the same pair being fixedly joined at the area of the acute vertex of the trapezoid located in the larger base of the trapezoid to a respective flange of the flexible central element and at the rectangular side of the trapezoid joined to the edging of the respective rigid frame, the end ribs of one and the same pair being arranged and configured in such a way that in the stripped position the trapezoids of each pair of ribs make contact along their sloping sides, which contact is lost upon passing to the operative formworking position, due to the action of the tensioning device, in which the larger bases of the trapezoids of the end ribs form an angle of approximately 90^Q.

According to another feature of the invention, the regulation system com- - A -

prises at least one pair of essentially planar, rectangular trapezoid-shaped inner ribs which are separated from one another, transversely arranged along the framework between the two pairs of end ribs, each inner rib of one and the same pair being fixedly joined at the area of its acute vertex located in the larger base of the trape- zoid to a respective flange of the flexible central element and at the rectangular side of the trapezoid joined to the edging of the respective rigid frame, the inner ribs of one and the same pair being arranged and configured in such a way that in the stripped position the trapezoids of each pair of ribs make contact along their sloping sides, which contact is lost upon passing to the operative formworking position, due to the action of the tensioning device, in which the larger bases of the trapezoids of the inner ribs form an angle of approximately 90^Q.

According to another feature of the invention, the end ribs and the inner ribs are rectangular-trapezoid shaped in which the acute angle forming the larger base of the trapezoid with the sloping side is considerably less than 45^Q. According to another feature of the invention, the inner ribs are parallel to the end ribs.

According to another feature of the invention, the areas of the acute vertices of the end and inner ribs are fixedly joined to the flanges of the flexible central element through a tubular or bar-shaped element extending parallel to the edges of the flanges of the mentioned flexible central element.

According to another feature of the invention, the end ribs, the inner ribs and the tubular or bar-shaped element are rigid metal elements.

According to another feature of the invention, each of the rigid frames is provided with an essentially rectangular board having an essentially planar main face, the smallest sides of the mentioned board being fixedly joined to respective end ribs and its larger sides fitted in the edging of the frame and in the respective flange of the flexible central element, arranged in such a way that the surface of the main face of a rigid frame is formed by the outer face of the board placed flush with the corresponding flange of the flexible central element. According to another feature of the invention, the boards are fixedly joined to the inner ribs.

According to another feature of the invention, the boards are fixedly joined to the inner ribs by means of a screwed assembly.

According to another feature of the invention, the regulation system com- prises at least one tie one of the ends of which is hingedly joined to an inner rib and the other end of which is hingedly and slidably joined to the other inner rib of the same pair, in such a way that the length of the mentioned tie limits the angle formed by the larger bases of the inner ribs of the mentioned pair to approximately a maxi- mum value of 90^Q in the operative formworking position while at the same time allowing the reduction of said angle in the stripped position to a value considerably less than 90^Q.

According to another feature of the invention, the tie is formed by an elongated element provided at its ends with respective through holes, one of said holes being an oblong hole.

According to another feature of the invention, the flexible central element is made of sheet metal.

Brief Description of the Drawings The attached drawings show, by way of a non-limiting example, a preferred embodiment of the connection framework at an inner corner meeting point object of the invention. In said drawings:

Figure 1 is a perspective view of a specific embodiment of the connection framework object of the invention; Figure 2 is a partial frontal elevational view of the framework of Figure 1 ;

Figure 3 is a side view of the framework of Figure 1 ;

Figure 4 is a detailed view of the framework according to section line B-B of Figure 1 ;

Figure 5 is a detailed view of the framework according to section line A-A of Figure 1 ;

Figure 6 is another perspective view of the framework of Figure 1 ; Figure 7 is a detailed view of an intermediate section of the framework of Figure 1 ;

Figure 8 is a detailed view of a tensioning device of the framework of Figure 1 ;

Figure 9 is another view of the tensioning device of Figure 8; and Figure 10 is a detailed view according to section line A-A of Figure 8. Detailed Description of the Drawings

Figures 1 and 6 show a connection framework 1 for forming the inner corner meeting point between two vertical structure formwork panels (not shown in the drawings). The framework 1 comprises two rigid frames each provided with an es- sentially planar main face 2, 2'. Each of the mentioned frames comprises in its central area a board 12 made of wood or a similar resistant material, in which one of its two faces with the largest surface receives the name of main face 2 or 2' due to the latter being the formworking face of one of the vertical structures of the corner meeting point. Each of the rigid frames is provided on its side with an edging 3, perpen- dicular to the plane of the respective main face 2, 2', provided with coupling means 4 for its coupling to the adjacent formwork panel in the operative formworking position of the vertical structure to which concrete is to be poured. Said coupling means are depicted in Figures 1 , 2 and 7 as through holes made in the edging 3. The actual edging 3 of each rigid frame serves to receive one of the larger sides of the cor- responding board 12 by means of fitting.

Furthermore, the framework 1 also comprises a flexible central corner connection element 5 connecting the two rigid frames along their entire length, the cross section of the mentioned flexible central element 5 generally being at a right angle. Said flexible central element 5 preferably consists of a strip of sheet metal formed in an L-shape, two planar and perpendicular flanges 5a and 5b thus being able to be distinguished. As can be seen in Figure 6, and in detail in Figures 4 and 5, the flexible central element 5 connects at a right angle the rigid frames of the framework 1 , said element being flush with the main faces 2 and 2' and configuring the arris of the inner corner. It should be mentioned that the previously described framework 1 comprises a regulation system by means of which the inner angle formed by the main faces 2 and 2' of the boards 12 arranged in the rigid frames in the operative formworking position can be varied, being able to adopt an angle considerably less than 90^Q in a stripped position by causing the deformation of the flexible central element 5 to thus facilitate that the framework 1 , and specifically the main faces 2, 2' of the rigid frames connected by the flexible central element 5, can be easily separated from the concrete surface of the 90^Q inner corner.

The mentioned regulation system of the framework 1 depicted in Figure 1 comprises two tensioning devices 6 which can be manually operated through the part 66 shown in detail in Figure 8. The ends of each tensioning device 6 are joined to the edging 3 of the sides of the rigid frames, such that when each tensioning device 6 is operated, its ends exert a tractive force on the mentioned sides and therefore the inner angle between the main faces 2 and 2' progressively decreases. Therefore in order to go from the operative formworking position, in which the angle between the main faces 2 and 2' is 90^Q, to the non-operative stripped position, an operator must simply manually operate the tensioning device, turning part 66, whereby the angle between the main faces 2 and 2' decreases and said faces gradually lose contact with the concrete surface until being completely separated from it, being able to remove the framework 1 without needing to use a crane or similar machine that forcefully pulls on the framework 1.

Figures 9 and 10 show a detail of the configuration of a tensioning device 6. The tensioning device 6 is formed by an axial element 61 provided with two externally threaded ends 62 and 63, one with a right-hand thread and the other with a left-hand thread, for operating the tensioning device 6 by turning part 66 in one direction or the other, depending on whether the angle is to be reduced to strip the formwork or if the angle is to be restored to the value of 90^Q to form the inner corner. As can be seen in Figure 10, each of the threaded ends 62 and 63 is coupled to or introduced in a complementarily threaded perforation of an end tubular element 64 and 65, respectively. For their part, each end tubular element 64 and 65 is joined at its other end to the edging 3 of the side of the corresponding main face 2 and 2', respectively. As can be seen in Figure 8, the axial element 61 comprises a central section with a polygonal outer contour, such as one with a hexagonal threading, which part 66 shown in Figure 8 can be coupled to so as to facilitate the manual operation of the tensioning device 6 by an operator. Specifically, part 66 is formed by a central disc perimetrically provided with three cylindrical extensions to turn part 66, and therefore axial element 61 , with the hand, using a bar as a lever between two extensions or striking said cylindrical extensions with a hammer.

It can be seen that the framework of Figure 1 comprises two pairs of end ribs 7 -T and nine pairs of inner ribs 9-9', which ribs form part of the regulation system of the framework 1. Both the end ribs 7, T and the inner ribs 9, 9' are essentially planar rectangular trapezoid-shaped, as seen in detail in Figures 3, 4 and 5. It should be mentioned that the end ribs 7 and T and the inner ribs 9 and 9' of one and the same pair are independent metal parts, i.e. they are not joined directly to one another by any of their sections.

Each pair of end ribs 7 -T is transversely arranged at a respective longitudinal end of the framework 1 like a cover, whereas the pairs of inner ribs 9-9' are transversely distributed throughout the framework 1 between the two pairs of end ribs 7 -T.

Each end rib 7, T of one and the same pair is fixedly joined at the end of the larger base 8a of the trapezoid with an acute vertex to a respective flange 5a and 5b of the flexible central element through a tubular or bar-shaped element 1 1 extending parallel to the edges of the mentioned flanges 5a and 5b. In particular, both the joint between the vertex of the trapezoid of a rib to the bar-shaped mentioned element 1 1 and the joint of the latter to the respective flange 5a and 5b of the flexible central element are fixed welded joints. Furthermore, the rectangular side 8b of the trapezoid of the end rib 7 or T is joined to the edging 3 of the side of the main face 2 or 2', respectively. The end ribs 7, T of one and the same pair are arranged and con- figured such that in the formworking position, the larger bases 8a of the trapezoids form an approximately 90^Q angle, end rib 7 barely making any physical contact with ribs T of the same pair, as shown in Figure 3. In contrast, in the stripped position of the framework 1 , the trapezoids of each pair of end ribs 7-7' make contact along their sloping sides 8c. The assembly described for the end ribs 7, T is the same as the assembly used for the inner ribs 9, 9', according to which each inner rib 9, 9' of one and the same pair is fixedly joined at the area of the acute vertex of its larger base 10a to a respective flange 5a and 5b of the flexible central element through the corresponding tubular or bar-shaped element 1 1. Also in a similar manner, the rectangular side 10b of the trapezoid of the inner rib 9 or 9' is joined to the edging 3 of the side of the main face 2 or 2', respectively. The inner ribs 9, 9' of one and the same pair are arranged and configured such that in the formworking position, the larger bases 10a of the trapezoids form an angle of approximately 90^Q, inner rib 9 barely making any physical contact with inner rib 9' of the same pair, as can be seen in Figures 4, 5 and 7. In contrast, in the stripped position of the framework 1 , the trapezoids of each pair of inner ribs 9-9' make contact along their sloping sides 10c.

As can be seen Figures 3, 4, 5 7, the end ribs 7, T and the inner ribs 9, 9' are rectangular trapezoid-shaped in which the acute angle formed by the larger base 8a or 10a of the trapezoid with the sloping side 8c or 10c is considerably less than 45^Q so that the angle formed by the main faces 2 and 2' in the stripped position reaches a value considerably less than 90^Q and thus the framework 1 can easily be removed from the inner corner in which concrete has been applied.

In addition to the tensioning devices 6, the end ribs 7, 7', the inner ribs 9, 9' and the bar-shaped element 1 1 , the regulation system of the framework 1 also comprises a plurality of ties 14 which limit the maximum opening of the corner angle. As shown in detail in Figure 5, tie 14 is a preferably metallic, elongated element one of the ends of which is hingedly joined to an inner rib 9 and the other end is hingedly and slidably joined to the other inner rib 9' thereof through the oblong hole 15 made in said end, such that the length of the tie 14 limits the angle formed by the larger bases 10a of the inner ribs 9, 9' of the mentioned pair to approximately a maximum value of 90^Q in the operative formworking position, allowing the reduction of said angle in the stripped position to a value considerably less than 90^Q.

Therefore, to prepare the framework 1 for forming a corner, the operator will operate the tensioning device (or tensioning devices 6 if there is more than one) by turning part 66 so that the angle formed by the main faces 2, 2' increases up to a value of 90^Q. In fact, there comes a moment when the operator cannot turn part 66 any further because the ties 14 prevent the angle formed by the main faces 2, 2' from increasing and this moment coincides with the position in which the angle is 90^Q. 90^Q inner corners can thus be achieved with the framework 1 without having to use set squares to control the final angle in the formworking position, since the length of the ties and the arrangement of the oblong hole 15 are calculated to limit the maximum angle of opening to a value of 90^Q.

In relation to the fixing of the planar rectangular boards 12 defining the main faces 2, 2', formworking faces of the framework 1 , it should be mentioned that the smaller sides of each board 12 are fixedly joined to a respective end rib 7, T and that its larger sides are respectively limited by the edging 3 and by the corresponding flange 5a or 5b of the flexible central element and the tubular or bar-shaped element 1 1 joined thereto. The surface defined by the main face 2 or 2' of the rigid frame is therefore formed by the outer face of the corresponding board 12 placed flush with the corresponding flange 5a or 5b of the flexible central element 5. The boards 12 are fixedly joined to the inner ribs 9, 9' by means of a screwed assembly, as can be seen in Figure 7. It can be seen that the ribs 9, 9' have small tubular parts 13 welded thereto, inside which parts the end of the screw for fixing the boards 12 to th e mentioned ribs 9, 9 is housed'.

The operation of the inner corner connection framework 1 , and specifically of its regulation system for changing the angle formed by the main faces 2 and 2' of the rigid frames forming such system, will be explained blow. The starting situation is the formworking position in which the main faces 2 and 2' form a 90^Q angle. Once the concrete has been poured in the vertical structure, for example a wall, and specifically its corner section, and once the concrete has set, the framework 1 is stripped by operating the regulation system. To that end, one or several operators operate tensioning devices by turning part 66 clockwise. Turning part 66 makes axial element 61 turn and makes end tubular elements 64 and 65 come closer to one another, exerting traction on the hinged joints of the ends of the tensioning device to the edging 3. Said traction on the edging 3 makes the end ribs 7, T and the inner ribs 9, 9' angularly come closer to one another, pulling in this movement bringing them closer together the boards 12 joined to the mentioned ribs and at the same time causing the flanges 5a and 5b of the flexible central element 5 to bend due to the welded joint of such flanges to the ribs through the bar- shaped elements 1 1 . The operators will stop turning part 66 when the sloping sides of the ribs of one and the same pair make contact with one another, at which time the angle that will be formed by the main faces 2 and 2' will be less than 90^Q, having been considerably separated from the concrete surface and therefore making it possible to separate without difficulties the framework 1 from the inner corner to which concrete has been poured.

Claims

C L A I M S

1 .- A connection framework (1 ) at an inner corner meeting point between two vertical structure formwork panels comprising two rigid frames joined at one of their sides, each provided with an essentially planar main face (2, 2'), provided on their sides with an edging (3) provided with coupling means (4) for coupling to an adjacent formwork panel, said frames being joined such that the respective planar main faces form an inner corner with an angle of approximately 90^Q in a formworking position, characterized in that it comprises a flexible central corner connection element (5) connecting the two rigid frames along their whole length, the cross section of the mentioned central element generally being at a right angle, and a regulation system by means of which the inner angle forming the main faces of the rigid frames in formworking position can be varied, being able to adopt in a stripped position an angle considerably less than 90^Q by deforming the flexible central element, thus fa- cilitating the separation of the framework from the concrete surface of the 90^Q inner corner.

2.- A connection framework (1 ) at an inner corner meeting point according to claim 1 , characterized in that the regulation system comprises at least one tension- ing device (6) the ends of which are joined to the edging (3) of the sides of the rigid frames, in such a way that when the tensioning device is operated, its ends exert a tractive force on the mentioned sides progressively decreasing the inner angle between the main faces of the mentioned rigid frames.

3.- A connection framework (1 ) at an inner corner meeting point according to claim 2, characterized in that the tensioning device (6) is a manually operated one and is formed by an axial element (61 ) provided with two externally threaded ends (62, 63), one with a right-hand thread and the other with a left-hand thread, each of said threaded ends being coupled in the complementarily threaded perforation of a corresponding end tubular element (64, 65), each end tubular element being joined at its other end to the edging (3) of the side of a corresponding rigid frame of the framework.

4.- A connection framework (1 ) at an inner corner meeting point according to one of the previous claims, characterized in that the flexible central element (5) has an L-shaped cross section being provided with two flanges (5a, 5b).

5.- A connection framework (1 ) at an inner corner meeting point according to claims 3 and 4, characterized in that the regulation system comprises two pairs of essentially planar, rectangular trapezoid-shaped end ribs (7, V) which are independent from one another, arranged transversely at the longitudinal ends of the framework like a cover, each end rib of one and the same pair being fixedly joined at the area of the acute vertex of the trapezoid located in the larger base (8a) of the trapezoid to a respective flange (5a, 5b) of the flexible central element (5) and at the rectangular side (8b) of the trapezoid joined to the edging (3) of the respective rigid frame, the end ribs of one and the same pair being arranged and configured in such a way that in the stripped position the trapezoids of each pair of ribs make contact along their sloping sides (8c), which contact is lost upon passing to the operative formworking position, due to the action of the tensioning device (6), in which the larger bases of the trapezoids of the end ribs form an angle of approximately 90^Q.

6.- A connection framework (1 ) at an inner corner meeting point according to claim 5, characterized in that the regulation system comprises at least one pair of essentially planar, rectangular trapezoid-shaped inner ribs (9, 9') which are independent from one another, transversely arranged along the framework between the two pairs of end ribs (7, 7'), each inner rib of one and the same pair being fixedly joined at the area of its acute vertex located on the larger base (10a) of the trapezoid to a respective flange of the flexible central element and at the rectangular side (10b) of the trapezoid joined to the edging (3) of the respective rigid frame, the inner ribs of one and the same pair being arranged and configured such that in the stripped position the trapezoids of each pair of ribs make contact along their sloping sides (10c), which contact is lost upon passing to the operative formworking position, due to the action of the tensioning device (6), in which the larger bases of the trapezoids of the inner ribs form an angle of approximately 90^Q.

7.- A connection framework (1 ) at an inner corner meeting point according to claim 6, characterized in that the end ribs (7, 7') and the inner ribs (9, 9') are rectangular trapezoid-shaped in which the acute angle formed by the larger base (8a, 10a) of the trapezoid with the sloping side is considerably less than 45^Q.

8.- A connection framework (1 ) at an inner corner meeting point according to claim 7, characterized in that the inner ribs (9, 9') are parallel to the end ribs (7, T).

9.- A connection framework (1 ) at an inner corner meeting point according to claim 8, characterized in that the areas of the acute vertices of the end ribs (7, T) and inner ribs (9, 9') are fixedly joined to the flanges (5a, 5b) of the flexible central element (5) through a tubular or bar-shaped element (1 1 ) extending parallel to the edges of the flanges of the mentioned flexible central element.

10.- A connection framework (1 ) at an inner corner meeting point according to claim 9, characterized in that the end ribs (7, T), the inner ribs (9, 9') and the tubular or bar-shaped element (1 1 ) are rigid metal elements.

1 1 .- A connection framework (1 ) at an inner corner meeting point according to claim 10, characterized in that each of the rigid frames is provided with an essentially rectangular board (12) having an essentially planar main face (2, 2'), the smallest sides of the mentioned board being fixedly joined to respective end ribs (7; T) and its larger sides fitted in the edging (3) of the frame and in the respective flange (5a; 5b) of the flexible central element (5), arranged in such a way that the surface of the main face of a rigid frame is formed by the outer face of the board placed flush with the corresponding flange of the flexible central element.

12.- A connection framework (1 ) at an inner corner meeting point according to claim 1 1 , characterized in that the boards (12) are fixedly joined to the inner ribs (9, 9').

13.- A connection framework (1 ) at an inner corner meeting point according to claim 12, characterized in that the boards (12) are fixedly joined to the inner ribs (9, 9') by means of a screwed assembly (13).

14.- A connection framework (1 ) at an inner corner meeting point according to one of claims 6 to 13, characterized in that the regulation system comprises at least one tie (14) one of the ends of which is hingedly joined to an inner rib (9) and the other end is hingedly and slidably joined to the other inner rib (9') of the same pair, in such a way that the length of the mentioned tie limits the angle formed by the larger bases of the inner ribs of the mentioned pair to approximately a maximum value of 90^Q in the operative formworking position while at the same time it allows reducing said angle in the stripped position to a value considerably less than 90^Q.

15.- A connection framework (1 ) at an inner corner meeting point according to claim 14, characterized in that the tie (14) is formed by an elongated element pro- vided with respective through holes at its ends, one of said holes being an oblong hole (15).

16.- A connection framework (1 ) at an inner corner meeting point according to one of the previous claims, characterized in that the flexible central element (5) is made of sheet metal.