The present invention relates to a door leaf for security doors, of the type comprising a central body and a lock housing designed to contain a lock unit, wherein the central body has a pair of opposite vertical sides, namely a first vertical side facing the lock housing and a second vertical side on the opposite side to the lock housing, and a pair of opposite horizontal sides, namely a top side and a bottom side, respectively, as specified in the preamble of independent claim 1.

The object of the present invention is to provide a door leaf for security doors which has a high structural strength and a high resistance to attacks and which can be produced in a simple, rapid and low-cost manner. A further object of the present invention is to provide a door leaf for security doors which has high thermal insulation and noise damping characteristics.

This and other objects are fully achieved according to the present invention by means of a door leaf for security doors as specified in independent claim 1.

Further advantageous features of the invention are indicated in the dependent claims, the contents of which are to be understood as forming an integral and complementary part of the description below.

In short, the invention is based on the idea of providing a door leaf for security doors, in which the central body comprises a first half-shell, a second half-shell, at least one first reinforcing element arranged along the first vertical side of the central body, at least one second reinforcing element arranged along the second vertical side of the central body, and a first plurality of threaded inserts arranged along the first vertical side of the central body, wherein the first half-shell, the second half-shell, the first reinforcing element(s) and the second reinforcing element(s) are rigidly joined together by means of interlocking engagement, and wherein the lock housing is rigidly joined to the central body by means of the first plurality of threaded inserts. Owing to the modular structure of the door leaf, with the lock housing that is formed as a part of the door leaf separate from the central body and is joined to the central body along a vertical side thereof, it is possible to obtain various combinations of central body and lock housing, and therefore various types of door leaf, which are different from each other for example in terms of level of resistance to attacks and/or in terms of thermal insulation or noise damping characteristics, by combining for example with a same lock housing different central bodies, which differ from each other for example in terms of thickness of the sheet of steel from which they are made. Moreover, the interlocking engagement between the various components of the central body (first half-shell, second half-shell, first reinforcing element(s) and second reinforcing element(s)) allows a quick and easy assembly of the door leaf, without adversely affecting the structural strength and the resistance to attacks thereof.

Preferably, the first reinforcing element(s), the second reinforcing element(s) and a main portion of the lock housing are formed as U- or C-shaped profiles.

Preferably, the central body of the door leaf further comprises a second plurality of threaded inserts arranged along the second vertical side of the central body for fixing hinges and/or a third plurality of threaded inserts arranged along the bottom horizontal side of the central body for fixing a movable sill.

According to an embodiment, the central body, and optionally also the lock housing, is at least partially filled with heat-insulating and/or sound-proofing material, preferably a polymeric material, such as a polyurethane foam or a polyurethane foam associated with one or more different (inert and/or non-inert) materials.

Preferably, the lock housing further comprises two covers which are arranged at the opposite longitudinal ends of the main portion and are rigidly joined to the latter by means of interlocking engagement.

According to an embodiment, the lock unit is joined to the lock housing by means of interlocking engagement. Preferably, the door leaf further comprises covering panels which are removably joined by means of quick-fit and quick-release coupling members, such as elastic clips, to a front side and/or to a rear side of the central body of the door leaf.

According to an embodiment, the central body comprises a single first reinforcing element which has a longitudinal extension equal to the height of the central body and is, preferably, rigidly joined by means of interlocking engagement both to the first half-shell and to the second half-shell of the central body.

According to a further aspect of the invention, the first half-shell of the central body of the door leaf comprises a flat wall with a rectangular shape, a first edge folded at a right angle to the flat wall along a greater side thereof, and a pair of second edges which are folded at right angles to the flat wall along the smaller sides thereof and are joined to the first edge by means of interlocking engagement.

Further features and advantages of the present invention will become clearer from the following detailed description provided purely by way of a non-limiting example, with reference to the accompanying drawings in which:

Figure 1 shows a perspective view of a door leaf for security doors according to an embodiment of the present invention;

Figure 2 is an exploded view of the central body of the door leaf of Figure 1 ;

Figure 3 is an exploded view of the lock housing of the door leaf of Figure 1 ;

Figure 4 is a plan view from above of a security door comprising the door leaf of Figure 1 ;

Figure 5 is a perspective view which shows the first half-shell of the central body of the door leaf of Figure 1 during an intermediate stage of the associated manufacturing method, with a first edge already folded at a right angle and with the two adjacent edges not yet folded;

Figure 6 is a view, on an enlarged scale, of the detail F shown in Figure 5;

Figures 6a to 6c show in sequence, on an enlarged scale, the folding of one of the two aforementioned adjacent edges of the first half-shell, starting from the condition shown in Figure 6, until this second edge is engaged with the first edge by means of interlocking engagement;

Figure 7 is a perspective view which shows the first half-shell and the hinge reinforcing element of the central body of the door leaf of Figure 1 , before interlocking engagement between these two components;

Figures 8a and 8b show, on an enlarged scale, a detail of the first half-shell and of the second hinge reinforcing element shown in Figure 7, in the non-engaged and engaged condition, respectively;

Figure 9 is a perspective view which shows the first half-shell of the central body of the door leaf of Figure 1, with the hinge reinforcing element and the housing reinforcing element both joined to the first half-shell;

Figure 10 shows in detail, on an enlarged scale, a bottom end portion of the housing reinforcing element of the central body of the door leaf of Figure 1, in the condition joined to the first half-shell;

Figure 11 is a perspective view which shows the central body of the door leaf of Figure 1 during an intermediate step of the associated assembly procedure, in which the second half-shell is partially joined to the housing reinforcing element;

Figure 12 is a view, on an enlarged scale, of the detail H shown in Figure 1 1 ;

Figure 13 is a perspective view which shows the central body of the door leaf of Figure 1 during an intermediate step of the associated assembly procedure, in which the second half-shell is almost fully joined to the first half-shell;

Figure 14 is a perspective view which shows in detail the bottom side of the central body of the door leaf of Figure 1 in the assembled condition;

Figure 15 is a perspective view which shows in detail a cover of the lock housing of Figure 3, together with the respective end of the main portion of the lock housing; and

Figures 16a and 16b are perspective views which show the door leaf of Figure 1, along with the lock unit, in a disassembled condition and during an intermediate step of the associated assembly procedure, respectively.

With reference initially to Figures 1 to 4, a door leaf for security doors according to an embodiment of the present invention is generally indicated 10. The door leaf 10 basically comprises a central body 12 and a lock housing 14 for containing a lock unit 16 (shown in Figures 16a and 16b). Preferably, the central body 12 and the lock housing 14 are made of steel which is galvanized and/or painted and/or has different surface finishes.

The central body 12 has a pair of opposite vertical sides 12a and 12b, namely a first vertical side 12a facing the lock housing 14 and a second vertical side 12b (along which hinges - not shown - are intended to be mounted for hinged connection of the door leaf to a door frame - also not shown) on the opposite side to the lock housing 14, and a pair of opposite horizontal sides 12c and 12d, namely a top side and a bottom side, respectively.

As can be seen in particular in the exploded view of Figure 2, the central body 12 comprises a first half-shell 18 (bottom half-shell, according to the point of view of a person viewing Figure 2), a second half-shell 20 (top half-shell, according to the point of view of a person viewing Figure 2), a first reinforcing element 22 (hereinafter referred to as "housing reinforcing element") along the first vertical side 12a, and a second reinforcing element 24 (hereinafter referred to as "hinge reinforcing element") along the second vertical side 12b.

Preferably, the housing reinforcing element 22 and/or the hinge reinforcing element 24 are formed as U- or C-shaped profiles. Preferably, the housing reinforcing element 22 has a longitudinal extension equal to the height of the central body 12 (i.e. equal to the length of the first vertical side 12a). In the embodiment shown, the housing reinforcing element 22 is formed by a single part, but may also be formed by several separate parts, which are firmly connected together. The hinge reinforcing element 24 has preferably a longitudinal extension smaller than the height of the central body 12, as can be seen for example in Figure 7. In the embodiment shown, the hinge reinforcing element 24 is a single part, but several hinge reinforcing elements separate from each other may also be provided.

With reference to the exploded view of Figure 3, the lock housing 14 comprises a main portion 26 formed as a U- or C-shaped profile and two covers 28 which are rigidly joined (by means of interlocking engagement) to the opposite ends of the main portion 26 so as to close the lock housing 14 at the top and at the bottom.

As will be explained in detail further below, the aforementioned components of the central body 12, namely the first half-shell 18, second half-shell 20, the housing reinforcing element 22 and the hinge reinforcing element 24 are rigidly joined together by means of interlocking engagement. More precisely, in the embodiment shown, the housing reinforcing element 22 is joined by means of interlocking engagement both to the first half- shell 18 and to the second half-shell 20, the hinge reinforcing element 24 is joined by means of interlocking engagement to the first half-shell 18, and the second half-shell 20 is joined by means of interlocking engagement both to the first half-shall 18 and to the housing reinforcing element 22. The lock housing 14 is rigidly joined to the central body 12 thus assembled by means of first threaded and/or riveted inserts 30 (which can be seen for example in Figures 10 and 11) which are arranged along the first vertical side 12a of the central body 12 and more precisely are mounted on the housing reinforcing element 22.

Preferably, in order to improve the thermal and/or acoustic performance of the door the central body 12, and optionally also the lock housing 14, are filled with materials having heat-insulation and/or sound-proofing properties, in particular with polymeric materials, for example polyurethane foam and/or polyurethane foam associated with various (inert and/or non-inert) materials. Filling of the central body 12, and optionally also of the lock housing 14, with filling material also helps improve the structural strength of the door leaf. Therefore, for the same structural strength of the door leaf, it is possible to reduce the thickness of the sheet of steel from which the components of the door leaf are made, with a consequent reduction in the overall cost of the door leaf. As a filling material it is also possible to use an already foamed material, which is fixed by means of adhesive inside the door leaf.

With reference in particular to Figures 2 and 7, the first half-shell 18 comprises a flat wall 32 of rectangular shape, a first edge 34 folded at a right angle to the flat wall 32 along a longer side thereof (corresponding to the second vertical side 12b of the central body 12) and a pair of second edges 36 folded at right angles to the flat wall 32 along the shorter sides thereof (corresponding to the top horizontal side 12c and the bottom horizontal side 12d, respectively). The first edge 34 extends over the entire length (height) of the flat wall 32. The second edges 36 are instead shorter than the short sides of the flat wall 32, so that an edge portion 38 of the flat wall 32, arranged on the opposite to the first edge 34, projects outwards from the first half-shell 18 with respect to the second edges 36. The edge portion 38 is folded onto itself so as to define a seat 40 for interlocking engagement of the housing reinforcing element 22 with the first half-shell 18.

The first edge 34 of the first half-shell 18, in particular on the side of this edge facing the inside of the central body 12, is provided with a plurality of elastically deformable tongues 42, which are formed integrally with the first edge 34 and serve for interlocking engagement between the first half-shell 18 and the second half-shell 20, as well as for interlocking engagement between the second edges 36 and the first edge 34 of the first half-shell 18, and a plurality of tabs 44, which are also formed integrally with the first edge 34 and serve for interlocking engagement between the first half-shell 18 and the hinge reinforcing element 24. In the embodiment shown, the first edge 34 also has a plurality of holes 46 for insertion of the second threaded and/or riveted inserts 48 (which can be seen in particular in Figures 9 and 13) which serve for fixing the hinges to the door leaf 10.

According to the embodiment shown, the two second edges 36 of the first half-shell 18 have a plurality of holes 50 for inserting third threaded and/or riveted inserts 52 (shown in Figures 4 and 14). The threaded and/or riveted inserts 52 provided on the bottom side of the central body 12 of the door leaf serve, for example, for fixing a movable sill (not shown).

The second edges 36 are joined to the first edge 34 of the first half-shell 18 by means of interlocking engagement, in particular by means of forced insertion of connecting lugs 36a, each of which extends at a right angle from the end of the respective second edge 36 facing the first edge 34, between the first edge 34 and one of the elastically deformable tongues 42 formed by the first edge 34, said insertion being obtained with the right-angled folding of the second edge 36 with respect to the flat wall 32. The sequence of operations required to join one of the two second edges 36 together with the first edge 34 of the first half-shell 18 is shown in Figures 6, 6a, 6b and 6c.

The method for assembling the central body 12 of the door leaf envisages firstly that, once the first half-shell 18 has been formed, the hinge reinforcing element 24 is rigidly joined by means of interlocking engagement to the first half-shell 18, in particular to the first edge 34 thereof, as shown in Figures 7, 8a and 8b. More specifically, according to the embodiment shown the interlocking engagement between the hinge reinforcement 24 and the edge 34 of the first half-shell 18 is obtained by means of insertion of tongues 54 of the hinge reinforcing element 24 into the tabs 44 of the first edge 34. Then, as shown in Figures 9 and 10, the housing reinforcing element 22 is rigidly joined to the first half-shell 18 by means of interlocking engagement. More specifically, according to the embodiment shown, the interlocking engagement between the housing reinforcing element 22 and the first half-shell 18 is obtained by means of insertion of one of the two side walls (indicated 22a) of the U- or C-shaped section of the housing reinforcing element 22 into the seat 40 formed by the folded edge 38 of the first half-shell 18. The folded edge of the first half- shell 18 is also provided with elastically deformable lugs 56 which prevent extraction of the side wall 22a of the housing reinforcing element 22 from the seat 40. Finally, the second half-shell 20 is also mounted on the assembly formed by the first half-shell 18, the housing reinforcing element 22 and the hinge reinforcing element 24, again by means of interlocking engagement, as shown in Figures 1 1, 12 and 13. More specifically, according to the embodiment shown, an edge 58, folded onto itself, of the second half-shell 20 forms a seat 60, similar to the seat 40 formed by the edge 38, in which a side wall 22b, parallel to the side wall 22a, of the housing reinforcing element 22 is inserted. Furthermore, a plurality of folded edges 62 (shown in Figures 2 and 13), which extend at right angles to a flat wall 64 of the second half-shell 20 from the side of the flat wall 64 opposite to the edge 58, are inserted between the edge 34 of the first half-shell 18 and the elastically deformable tongues 42.

As shown in Figure 15, the lock housing 14 is assembled by rigidly joining each cover 28 to the main portion 26 by means of interlocking engagement. More specifically, in the embodiment shown, the interlocking engagement between each cover 28 and the main portion 26 of the lock housing 14 is obtained by means of insertion of tongues 66 of the cover 28 into respective tabs 68 formed in the main portion 26, as well as advantageously by means of engagement of locking teeth 70 of the cover 28 into respective slots 72 provided in the main portion 26. The lock housing 14 thus assembled is then rigidly joined to the central body 12 of the door leaf, in particular to the housing reinforcing element 22, by means of screws (not shown) inserted into the first inserts 30.

The lock unit 16 is also advantageously joined to the door leaf 12, and more precisely to the lock housing 14, by means of interlocking engagement, as shown in Figures 16a and 16b. The interlocking engagement between the lock unit 16 and the lock housing 14 is for example obtained by means of insertion of tongues 74 of the lock unit 16 into respective tabs 76 provided in the main portion 26 of the lock housing 14.

The door leaf 10 thus obtained may be advantageously equipped, in order to complete the leaf of the security door, with hinges, riders, additional covers for the sides (fairing) and for the front and rear sides (decorative panels 78 - Figure 4). In order to fix the panels 78 and 80 to the door leaf 10 a releasable fixing system is advantageously provided, which consists of quick-fit and quick-release elements (not shown), such as elastic clips, engaging in suitable openings 80 provided on the two sides, i.e. the front side and the rear side, of the central body 12 of the door leaf.

In the light of the description provided above, the advantages which may be achieved with a door leaf for security doors according to the present invention are evident.

Firstly, the door leaf for security doors according to the invention has a modular structure. The central body is equipped with all the necessary arrangements for assembly of the various closing elements and accessories so as to allow the subsequent customization of the door leaf depending on the specific requirements set by the customer. The lock housing is configured to receive different closure types and systems (e.g. mechanical, electromechanical or electronic lock units, alarms and sensors, access and communications control systems) which can be installed and removed easily and rapidly. The advantages resulting therefrom are thus both of an economic nature - such as more efficient warehouse management, with a reduction in the warehouse stocks, faster production and assembly, possibility of sending modules in batches for assembly directly at the customer's premises, with a reduction in the transportation costs owing to the possibility of optimizing the packages and loads - and of a commercial nature, such as the possibility of customization of the door with a shorter lead time and lower maintenance costs, owing to easy removal and assembly of the parts to be replaced.

Moreover, owing to the use of interlocking engagements, it is possible to eliminate entirely welding as a method for connecting together components of the central body of the door leaf. The advantages in terms of energy savings and environmental sustainability are evident. Further advantages resulting therefrom are the absence of initial corrosion points (which are frequent in case of welded sheet metal) and the reduction in the cycle time for production of the door leafs, with consequent economic advantages.

Moreover, compared to the prior art, with the door leaf for security doors according to the invention it is possible to reduce the amount of steel used, for the same structural strength and resistance to attacks, owing to filling of the central body, and optionally also of the lock housing, with filling material. By filling the central body, and optionally also the lock housing, with a filling material having heat-insulation and/or sound-proofing properties it is also possible to increase the thermal insulation and/or noise damping characteristics of the door.

Furthermore, the arrangement and configuration of the door leaf for security doors according to the invention are such that the leaf of the security door is reversible, in the sense that the door may be mounted with a "left-hand" or "right-hand" opening direction, since the design of the components and of the leaf is symmetrical with respect to a plane passing through the axes of the lock bolts. Owing also to the reversibility of the frame with which the door leaf according to the invention may combined and the reversibility of the hinges with which the door leaf according to the invention may be provided, it is possible to obtain a security door which is completely reversible, in the sense that the door may be mounted equally well with "left-hand" opening direction or "right-hand" opening direction, without having to replace any components or provide any additional components.

Naturally, the principle of the invention remaining unchanged, the embodiments and the constructional details may vary widely from those described and illustrated purely by way of non-limiting example, without thereby departing from the scope of the invention as defined in the accompanying claims.