FR3042395A1 - CONSTRUCTION ASSEMBLY FOR FURNITURE STRUCTURE. - Google Patents

Abstract

Construction kit (1) for a structure, in particular for furniture, said building assembly comprising: - an element (10) comprising two threaded holes (11, 12, 13, 14), - a cube (50) presenting A first passage assembly (61, 62) extending in a first direction (X), a second passage assembly (63, 64) extending in a second direction (Y), a third set of passage (65, 66) extending in a third direction (Z) perpendicular to the first direction and in the second direction, and - a pair of two screws (41, 42). The building assembly (1) is adapted to occupy a first assembled position, a second assembled position and a third assembled position in which the rod (41b, 42b) of the screws (41, 42) extends respectively in the first assembly passageway, the second passage assembly and the third passage assembly, and is screwed into said element.

Description

Construction set for furniture structure.

Field of the Invention The invention relates to a structural assembly for a structure, in particular for furniture.

Context of the invention

Various structures are known for making furniture, such as tables, shelves and the like, by fixing plates on these structures. Some of these structures use cubes connected by joining elements. The object of the invention is to provide a construction assembly that is simple to produce and therefore inexpensive, but also simple to assemble, robust and aesthetic.

Presentation of the invention

To do this, according to the invention, the assembly of construction comprises: an element extending in an elongation direction between a front end and a distal end, said element comprising two threaded holes extending in the direction of elongation, a cube having: a first passage assembly extending in a first direction parallel to the longitudinal direction; a second passage assembly extending in a second direction, said second direction being perpendicular to the first direction; direction, • a third passage assembly extending in a third direction, said third direction being perpendicular to the first direction and the second direction, - a pair of screws, each screw having a head and a stem, said rod having a threaded portion, and said building assembly is adapted to occupy: - a first posit assembled ion in which: • the longitudinal direction of the element is parallel to the first direction, • the rod of each screw extends in a first direction in the first set of passage of the cube and is screwed into one of the threaded holes of said element, and • the head of each screw keeps the cube bearing against said element in the first direction, - a second assembled position in which: • the longitudinal direction of the element is parallel to the second direction, • the rod of at least one of the screws extends along the second direction in the second passage assembly of the cube and is screwed into one of the threaded holes of said element, and the head of at least one of the screws holds the cube in abutment with said element in the second direction, - a third assembled position in which: • the longitudinal direction of the element is parallel to the third direction, • the rod at least one of the screws extends along the third direction in the third passage assembly of the cube and is screwed into one of the threaded holes of said element, and • the head of the screw holds the cube in abutment against said element according to the third direction.

Thus, the element is easily assembled and robustly in three directions perpendicular to the cube. Fixing the cube on the element by two screws simplifies the positioning of the element relative to the cube and prevents the rotation of the element around the longitudinal direction.

According to the invention, the assembly of construction preferably also has the following characteristics: the cube has a first bearing face and a first opposite face extending substantially perpendicular to the first direction; the support faces the front end of the element in said first assembled position, and - each of the two screws is inserted through the cube into the first passage assembly from the first opposite face.

Thus, the assembly of the element on the cube is thus further facilitated.

According to a complementary feature according to the invention, preferably, in the first assembled position the stem of each screw extends through the cube over more than half the distance between the first bearing face and the first opposite face said distance being referred to as the cube side.

Thus, the robustness of fixing the element on the cube in the first position is increased.

Preferably, in the second assembled position and in the third assembled position, the shank of each screw extends across the cube over a distance of half the cube side.

According to yet another complementary feature according to the invention, in the first assembled position, the head of each screw is preferably embedded in a counterbore.

Thus, the heads of the screws do not project relative to the first opposite face, which improves the aesthetics of the building assembly.

According to another characteristic according to the invention, preferably said assembly is able to occupy an opposite assembled position in which: the longitudinal direction of the element is parallel to the first direction, the stem of each screw extends in a direction opposite to the first direction in the first set of passage of the cube and is screwed into one of the threaded holes of said element, and - the head of each screw maintains the cube relative to said element in the first direction.

Thus, the possibilities of assembly of the element on the cube are increased without significantly complicating the overall construction.

According to yet another characteristic according to the invention, preferably the first set of passage comprises a pair of first holes extending in the first direction, distinct and distant from each other in the second direction of a distance. spacer.

Thus, the assembly of the element on the cube is further facilitated and the positioning of the element relative to the cube is improved in the first assembled position.

According to the invention, the assembly of construction also preferably has the following additional characteristics: the second passage assembly comprises a pair of second holes extending in the second direction, distinct and distant from each other; another in the third direction of said spacing distance, - the third passage assembly comprises a pair of third holes extending in the third direction, separate and spaced apart from each other in the first direction of said distance from each other. spacing, and - the six holes constituting the first, second and third passage sets are all disjoint.

Thus, the assembly of the element on the cube is still facilitated and the positioning of the element relative to the cube is improved in the three assembled positions.

According to another characteristic according to the invention, the cube preferably has a central symmetry.

Thus, the assembly is facilitated since the user does not have to wonder about the position of the cube in order to fix the element there.

According to the invention, the assembly of construction preferably furthermore has the following characteristics: said element constitutes a first element and the assembly of construction further comprises a second element and a third element each comprising two threaded holes; said pair of screws constitutes a pair of first screws, said assembly of construction further comprises at least one second screw and at least one third screw each having a head and a rod, the second and third screws being identical to the first screws, said assembly is able to occupy a triple-assembled position in which: the longitudinal direction of the first element is parallel to the first direction; the stem of each of the first screws extends in the first direction in the first passage assembly; cube and is screwed into one of the threaded holes of said first element, and one of the first screws holds the cube in abutment against said element in the first direction, • the longitudinal direction of the second element is parallel to the second direction, • the stem of the second screw has a threaded portion, extends in the second direction in the second set of passage of the cube and is screwed into a threaded hole of said second element, • the head of the second screw keeps the cube bearing against said second element in the second direction, • the longitudinal direction of the third element is parallel to the third direction, • the rod of the third screw has a threaded portion, extends in the third direction in the third set of passage of the cube and is screwed into a threaded hole of said third member, and • the head of the third screw maintains the cube bearing against said third element in the third direction.

Thus, three elements are easily attached to the cube simultaneously and robustly.

According to the invention, the assembly of construction preferably furthermore has the following additional features: said element constitutes a first element and the assembly of construction further comprises a second element and a third element each extending between a front end and a distal end, the first, second and third elements each comprising four tapped holes at their end end, - said pair of screws constitutes a pair of first screws, said assembly of construction further comprises a pair of second screws and a pair of third screws each having a head and a rod, the second and third screws being identical to the first screws, - said assembly is adapted to occupy a triple-assembled position in which: • the longitudinal direction of the first element is parallel to the first direction, • the stem of each of the first re screw extends in the first direction in the first set of passage of the cube and is screwed into one of the threaded holes of said first element, and • the head of each of the first screws maintains the cube in support against said element in the first direction , The longitudinal direction of the second element is parallel to the second direction, the stem of each of the second screws comprises a threaded portion, extends in the second direction in the second set of passage of the cube and is screwed into a threaded hole said second element, the head of each of the second screws keeps the cube bearing against said second element in the second direction, the longitudinal direction of the third element is parallel to the third direction, the rod of each of the third screws comprises a threaded portion, extends in the third direction in the third passage assembly u cube and is screwed into a threaded hole of said third element, and • the head of each of the third screw maintains the cube in abutment against said third element in the third direction.

The presence of two fixing screws in each of the three directions and the four holes at the front end of each of the elements further facilitates the positioning of the elements and further improves the robustness of the attachment of the elements to the cube.

BRIEF DESCRIPTION OF THE FIGURES Other features and advantages of the present invention will become apparent from the following detailed description, with reference to the accompanying drawings, in which: FIG. 1 shows in perspective an assembly of furniture comprising assemblies of construction according to the invention, - FIG. 2 is a partial perspective view in accordance with FIG. 2, exploded and on an enlarged scale showing a building assembly, FIG. 3 is a partial unexpanded perspective view of the building assembly shown in FIG. 2, FIG. 4 is a partial view in section along the plane indicated IV-IV in FIG.

Detailed description of the invention

FIG. 1 illustrates an assembly of furniture constituting a table 100 and comprising in particular a building assembly 1 and a plate 2. The building assembly 1 essentially comprises a first element 10, a second element 20, a third element 30, first screws 41, 42, second screws 43, 44, third screws 45, 46 and a cube 50.

Figures 2 to 4 show in more detail the assembly of construction 1. To allow a better understanding, in Figure 3, the cube 50 is shown in transparency.

Each of the first member 10, second member 20 and third member 30 extends in an elongation direction between a front end 10a, 20a, 30a and a distal end 10b, 20b, 30b. In the illustrated embodiment, the first element 10, second element 20 and third element 30 has, perpendicular to the longitudinal direction, a constant section between the front end 10a, 20a, 30a and the distalelOb end, 20b, 30b. The first element 10, second element 20 and third element 30 are preferably made by extruding material, in particular metal material.

In addition, each of the first element 10, second element 20 and third element 30 has a front face 15, 25, 35 at the front end 10a, 20a, 30a, a distal face at the distal end 10b, 20b, 30b and four side faces 16, 26, 36 extending between the front end 10a, 20a, 30a and the distal end 10b, 20b, 30b. The first element 10, second element 20 and third element 30 has, in section perpendicular to their direction of elongation, a substantially square outer shape.

Each of the lateral faces 15, 25, 35 has two grooves 17, 18; 27, 28; 37, 38. The plate 2 is received in the grooves 17, 27 of the first elements 10 and second elements 20.

Each of the first member 10, second member 20 and third member 30 further comprises a first pair of holes 11, 12; 21.22; 31, 32 and a second pair of holes 13, 14; 23, 24; 33, 34 extending continuously in the longitudinal direction between the front end 10a, 20a, 30a and the distal end 10b, 20b, 30b. The first pair of holes 11, 12; 21.22; 31, 32 and the second pair of holes 13, 14; 23, 24; 33, 34 are threaded at least near the front end 10a, 20a, 30a and the distal end 10b, 20b, 30b. In the embodiment, only one pair of threaded holes per element end is used at a time, making the other pair of threaded holes optional and essentially useful to facilitate assembly of the first element 10, second element 20 and third element 30 with the cube 50.

In the illustrated embodiment, the cube 50 has a central symmetry.

The cube 50 has a first bearing face 51 and a first opposite face 54 both substantially planar and extending perpendicularly to a first direction X. The cube 50 further has a second bearing face 52 and a second opposite face Both being substantially planar and extending perpendicular to a second direction Y, perpendicular to the first direction X. The cube 50 finally has a third bearing face 53 and a third opposite face 56 both substantially planar and extending perpendicularly at a third direction Z, perpendicular to the first direction X and the second direction Y.

The cube 50 furthermore has a first passage assembly, formed in the embodiment illustrated by two first distinct passage holes 61, 62 and spaced from each other by a spacing distance D in the second direction. Y. The first through holes 61, 62 are through and extend along the first direction X. The cube 50 also has a second passage assembly, formed in the embodiment illustrated by two separate second through holes 63, 64. and spaced from each other by the spacing distance D along the third direction Z. The second through holes 63, 64 are traversing and extend in the second direction Y. The cube 50 finally presents a third set passageway, formed in the embodiment illustrated by two third passage holes 65, 66 separate and spaced from each other by the spacing distance D in the first direction X. The third through holes 61,62 are through and extend in the third direction Y.

The cube 50 furthermore has two countersinks 71, 72 in the first opposite face 54 at the end of the through holes 41, 42, two countersinks 73, 74 in the second opposite face 55 at the end of the through holes 43, 44 and two counterbores 75, 76 in the third opposite face 56 at the end of the through holes 45, 46. To facilitate the assembly of the first element 10, second element 20 and third element 30 with the cube 50, the cube 50 also has two counterbores (visible in FIG. 4) in the first bearing face 51 at the end of the through holes 41, 42, two countersinks in the second bearing face at the end of the through holes 43, 44 and two countersinks in the third bearing face 53 at the end of the through holes 45, 46.

In the illustrated embodiment, the first screws 41, 42, the second screws 43, 44 and the third screws 45, 46 are all identical and each have a head 41a, 42a; 43a, 44a; 45a, 46 and a rod 41b, 42b; 43b, 44b; 45b, 46b. The stem of each of the screws 41, 42, 43, 44, 45, 46 comprises a threaded portion 41c, 42c, 43c, 44c, 45c, 46c.

The figures representing the building assembly in a triple assembled position.

In this triple-assembled position, the longitudinal direction of the first element 10 extends along the first direction X. The first bearing face 51 is facing the front face 15 of the first element 10. The threaded portion 41c, 42c of the first screws 41, 42 cooperates with the first pair of threaded holes 11, 12 of the first element 10. The rod 41b, 42b of the first screws 41, 42 extends in the first through holes 61, 62. The first screws 41, 42 are screwed so that their head 41a, 42a bears under pressure in the first direction X against the cube 50, more precisely against a stop face 71a, 72a at the bottom of countersinks 71,72, as illustrated in FIG. FIG. 4. The first bearing face 51 is thus held in abutment with a force against the front face 15 of the first element 10.

The longitudinal direction of the second element 20 extends along the second direction Y. The second bearing face 52 is facing the front face 25 of the second element 20. The threaded portion 43c, 44c of the second screws 43, 44 cooperates with the first pair of threaded holes 21, 22 of the second element 20. The rod 43b, 44b of the second screws 43, 44 extends in the second through holes 63, 64. The second screws 43, 44 are screwed so that their head 43a, 44a comes under pressure under the second direction Y against the cube 50, more precisely against a stop face at the bottom of the counterbores 73, 74. The second bearing face 52 is thus held in abutment with a force against the front face 25 of the second element 20.

The longitudinal direction of the third element 30 extends along the third direction Z. The third bearing face 53 is facing the front face 35 of the third element 30. The threaded portion 45c, 46c of the third screws 45, 46 cooperates with the first pair of threaded holes 31, 32 of the third element. The rod 45b, 46b of the third screws 45, 46 extends in the third through holes 65, 66. The third screws 45, 46 are screwed so that their head 45a, 46a bears under pressure along the third direction Z against the cube 50, more precisely against a stop face at the bottom of counters 75, 76. The third bearing face 53 is thus held in abutment with a force against the front face 35 of the third element 30.

The first element 10, second element 20 and third element 30 advantageously differ from each other only by their length in the direction of elongation between the front end 10a, 20a, 30a and the distal end 10b, 20b, 30b. Therefore, the first element 10, second element 20 and third element 30 could perfectly be interchanged.

As illustrated in FIG. 4, the rod 41b, 42b of each screw extends through the cube 50 over a distance E extending between the bearing face 51, 52, 53 and the stop face 71a. , 72a counters 71,72, 73, 74, 75, 76. The distance E is greater than half, preferably greater than three quarters, the distance a between each bearing face 51, 52, 53 and the face opposite 54, 55, 56, the distance a usually being referred to as the cube side.

The heads 41a, 42a, 43a, 44a, 45a, 46a of the first screws 41, 42, second screws 43, 44 and third screws 45, 46 are embedded in the counterbores 71, 72, 73, 74, 75, 76, that is to say , they are set back respectively relative to the first opposite face 54, the second opposite face 55 and the third opposite face.

Further, in the illustrated embodiment, capped plugs 81, 82, 83, 84, 85, 86 are inserted into counters 71, 72, 73, 74, 75, 76 so as to completely obscure countersinks and screw, and flush with the first opposite face 54, second opposite face 55 and third opposite face 56. One and / or the other of the first element 10, second element 20 and third element 30 could be positioned in an assembly position opposite so that their direction of elongation always extends respectively along the first direction 10, the second direction 20 and the third direction 30, but that their proximal end 10a, 20a, 30a is respectively facing the first face opposite 54, the second opposite face 55 and / or the third opposite face 56 of the cube. The pair of first screws 41, 42, the pair of second screws 43, 44 and / or the pair of third screws 45, 46 then extend in opposite directions with respect to the three-fold position respectively in the first holes 41 , 42, the second through holes 43, 44 and / or the third through holes 45, 46.

Conversely, the first bearing face 51, second bearing face 52 and third bearing face 53 could bear against the distal face of one and / or the other of the first element 10, second element 20 and third element 30.

In addition, one or the other of the first screws 41, 42, second screws 43, 44 and third screws could be screwed into the second pair of holes 13, 14; 23, 24; 33, 34 of the first element 10, second element 20 and third element 30.

Therefore, there is complete compatibility between the screws 41, 42, 43, 44, 45, 46, the through holes 61, 62, 63, 64, 65, 66 in the cube and the tapped holes 11, 12, 13 14, 21, 22, 23, 24, 31, 32, 33, 34 in the elements 10, 20.

The table 100 shown in FIG. 1 comprises two first elements 10, two second elements 20, four third elements 30 and four cubes 50. It further comprises pedestals 4 screwed to the distal end 30 of the third elements and feet. adjustable by moving helical rotation under the bases.

Naturally, the invention is not limited to the embodiment (s) described for illustrative, non-limiting. Thus, the cubes may not be perfect cubes, the angle of the cubes being beveled so as to form for example twelve-sided shapes (six octagonal faces and six triangular faces).

In addition, the cube 50 could be made in two separate half-pieces in a median plane perpendicular to the first direction and assembled by gluing, in order to reduce the number of elements of the mold for making the cube. Alternatively, the two half-pieces could be connected by a dovetail or the like, the first screws passing through the two half-pieces holding them relative to each other. It will even be possible to fix the second element in abutment against the second bearing surface of the cube with one of the second screws and to fix an additional element bearing against the second opposite face of the cube with the other second screw, before to secure the two half-pieces with the first screws. Finally, to further simplify the molding in two half-pieces, the material between the third passage holes could be omitted to form a passage assembly incorporating the third passage holes, which would mold each of the half-pieces comprising only two molding elements. On the other hand, the plate 2 could be arranged on the first elements 10, second elements 20, third elements 30 and the cubes 50.

Claims (10)

A structural assembly (1) for a structure, particularly for furniture, said building assembly comprising: - an element (10) extending in an elongation direction between a front end (10a) and an end distal member (10b), said member comprising two threaded holes (11, 12, 13, 14) extending in the elongation direction at the front end (10a), - a cube (50) having: • a first set passageway (61,62) extending in a first direction (X) parallel to the longitudinal direction; • a second passage assembly (63,64) extending in a second direction (Y), said second direction (Y ) being perpendicular to the first direction (X), • a third passage assembly (65, 66) extending in a third direction (Z), said third direction (Z) being perpendicular to the first direction (X) and the second direction (Y), - a screw pair (41,42), each screw having a head (41a, 42a) and a shaft (41b, 42b), said shaft (41b, 42b) having a threaded portion (41c, 42c), said building assembly (41b, 42b), 1) is capable of occupying: a first assembled position in which: the longitudinal direction of the element is parallel to the first direction (X); the rod (41b, 42b) of each screw (41, 42); extends in a first direction in the first passage assembly (61,62) of the cube and is screwed into one of the threaded holes (11,12) of said element, and • the head (41a, 42a) of each screw (41 , 42) keeps the cube (50) bearing against said element (10) in the first direction (X), - a second assembled position in which: • the longitudinal direction of the element is parallel to the second direction (Y) , The rod of at least one of the screws extends along the second direction (Y) in the second passage assembly (63, 64) of the cube and is ssée in one of the threaded holes of said element, and • the head of at least one of the screws holds the cube in abutment against said element in the second direction (Y), - a third assembled position in which: • the longitudinal direction of the element is parallel to the third direction (Z), the rod of at least one of the screws extends in the third direction (Z) in the third passage assembly (65, 66) of the cube and is screwed into a threaded holes of said element, and • the head of the screw keeps the cube bearing against said element in the third direction (Z). 2. Building assembly according to claim 1 wherein: - the cube (50) has a first bearing face (51) and a first opposite face (54) extending substantially perpendicular to the first direction (X), - the first bearing face (51) faces the front end (10a) of the member (10) in said first assembled position, and - each of the two screws (41, 42) is inserted through the cube into the first passing assembly (61,62) from the first opposing face (44). 3. Building assembly according to the preceding claim wherein, in the first assembled position, the rod (41b, 42b) of each screw extends (E) through the cube over more than half the distance (a) between the first bearing face (51) and the first opposite face (54), said distance being referred to as the cube side. 4. Construction assembly according to the preceding claim wherein in the first assembled position, the head (41a, 42a) of each screw (41,42) is embedded in a countersink (71,72). 5. Construction assembly according to any one of the preceding claims wherein said building assembly is adapted to occupy an opposite assembled position in which: - the longitudinal direction of the element (10) is parallel to the first direction (X) the rod (41b, 42b) of each screw (41, 42) extends in a direction opposite to the first direction in the first passage assembly (61, 62) of the cube (50) and is screwed into one threaded holes (11,12) of said element, and - the head (41a, 42a) of each screw holds the cube (50) with respect to said element (10) in the first direction (X). A building assembly according to any one of the preceding claims wherein the first passage assembly comprises a pair of first holes (61, 62) extending in the first direction (X), separate and spaced apart from each other. another in the second direction of a distance (D). 7. Building assembly according to the preceding claim wherein: - the second passage assembly comprises a pair of second holes (63, 64) extending in the second direction (Y), separate and distant from each other along the third direction (Z) of said spacing distance (D), the third passage assembly comprises a pair of third holes (65, 66) extending in the third direction (Z), separate and apart from each other; one of the other following the first direction (X) of said spacing distance (D), and - the six holes (61, 62, 63, 64, 65, 66) constituting the first, second and third sets of passage are all disjointed. 8. Construction assembly according to any one of the preceding claims wherein the cube (50) has a central symmetry. 9. Building assembly according to any one of the preceding claims wherein: - said element constitutes a first element (10) and, the building assembly further comprises a second element (20) and a third element (30) comprising each two threaded holes (21,22; 31,32), - said pair of screws constitutes a pair of first screws (41,42), said assembly of construction further comprises at least a second screw (43,44) and at least one third screw (45, 46) each having a head (43a, 44a; 45a, 46a) and a shank (43b, 44b; 45a, 46a), the second (43, 44) and the third screw (45, 46). ) being identical to the first screws (41,42), - said assembly (1) is able to occupy a three-fold position in which: • the longitudinal direction of the first element (10) is parallel to the first direction (X), • the rod (41b, 42b) of each of the first screws (41, 42) extends in the first direction ( X) in the first passage assembly (61,62) of the cube and is screwed into one of the threaded holes (11, 12) of said first element (10), and • the head (41a, 42a) of each of the first screws ( 41, 42) keeps the cube (50) bearing against said element (10) in the first direction (X), • the longitudinal direction of the second element (20) is parallel to the second direction (Y), • the rod ( 43b, 44b) of the second screw (43, 44) comprises a threaded portion (43c, 44c), extends along the second direction (Y) in the second passage assembly (63, 64) of the cube (50) and is screwed into a threaded hole (21,22) of said second element (20), • the head (43a, 44a) of the second screw (43, 44) holds the cube (50) bearing against said second element (20) in the second direction (Y), • the longitudinal direction of the third member (30) is parallel to the third direction (Z), • the shank (45b, 46b) of the third screw (45, 46) comprises a threaded portion (45c, 46c), extends in the third direction (Z) in the third passage assembly (65, 66) of the cube (50) and is screwed into a threaded hole (31, 32) of said third element (30), and • the head (45a, 46a) of the third screw (45, 46) keeps the cube (50) bearing against said third element (30) in the third direction (Z). 10. Building assembly according to any one of claims 1 to 8 wherein: - said element constitutes a first element (10) and, the building assembly further comprises a second element (20) and a third element (30). ) each extending between a front end (10a, 20a, 30a) and a distal end (10b, 20b, 30b), the first, second and third members each comprising four tapped holes (11, 12, 13, 14; , 22, 23, 24, 31, 32, 33, 34), at their front end (10a, 20a, 30a), - said pair of screws constitutes a pair of first screws (41, 42), said assembly of construction comprises furthermore, a pair of second screws (43, 44) and a pair of third screws (45, 46) each having a head (43a, 44a, 45a, 46a) and a rod (43b, 44b, 45a, 46a), second screw (43, 44) and the third screws (45, 46) being identical to the first screws (41, 42), - said assembly (1) is able to occupy a tr in which: • the longitudinal direction of the first element (10) is parallel to the first direction (X), • the rod (41b, 42b) of each of the first screws (41, 42) extends in the first direction (X) in the first passage assembly (61,62) of the cube and is screwed into one of the threaded holes (11, 12) of said first member (10), and • the head (41a, 42a) of each of the first screws (41, 42) holds the cube (50) bearing against said element (10) in the first direction (X), • the longitudinal direction of the second element (20) is parallel to the second direction (Y), • the rod (43b, 44b) of each of the second screws (43, 44) comprises a threaded portion (43c, 44c), extends in the second direction (Y) in the second passage assembly (63, 64) of the cube (50 ) and is screwed into a threaded hole (21,22) of said second element (20), • the head (43a, 44a) of each of the second screws (43, 44) hand holds the cube (50) bearing against said second element (20) in the second direction (Y), • the longitudinal direction of the third element (30) is parallel to the third direction (Z), • the rod (45b, 46b ) of each of the third screws (45, 46) has a threaded portion (45c, 46c), extends in the third direction (Z) in the third passage assembly (65, 66) of the cube (50) and is screwed in a tapped hole (31,32) of said third member (30), and • the head (45a, 46a) of each of the third screws (45, 46) holds the cube (50) in abutment with said third member (30) following the third direction (Z).