A door frame

Abstract

The object of the utility model is a door frame adapted to be mounted in a wall with a door opening, comprising three parts: - a first strip (1), - a main beam (2), - a second strip (3a), in which the main beam (2) constitutes the central part of the door frame and has two fixing slots on its two opposite sides, namely the first and second fixing slots, adapted to fix the first (1) and second (3a) strips respectively, in which the first strip (1), constituting the adjustment strip of the door frame, and the second strip (3a), constituting the masking strip of the door frame, each having the form of an angled piece with a masking arm and the second fixing arm, in which the first strip (1) and the second strip (3a) are respectively fixed by their fixing arms in the fixing slots of the main beam (2),in which the main beam (2) of the door frame has, on the inside, on the side of the second fixing slot, a reinforced structure, characterized in that, relative to the free end of the fixing arm of the second strip, i.e., the end of the fixing arm that is not placed in the second fixing slot, the reinforced structure of the main beam (2) begins at a distance of respectively: - at least 45 mm, when the second strip (3a) is of the rebate type, - at least 60 mm, when the second strip is of the non-rebate type, and ends at a distance of at most 100 mm from said free end of the fixing arm of the second strip (3a). Figure 13,

Description

Title of the invention: A door frame

[0001] The object of the present utility model is a door frame, and more specifically an adjustable door frame, formed of several elements - two strips and the main beam of the door frame, which are specifically designed for interior use.

[0002] In the prior art, various types of door frames are known - both those used for mounting doors and sorts of "masking tunnels" mounted in openings in walls, forming decorative portals.

[0003] Many door frames available on the market are made of wood or plywood / chipboard, etc., which are highly desirable materials in most applications, but they can be damaged by contact with water or by prolonged exposure to high humidity (e.g., bathroom, laundry room, sauna, etc.). An assembly for creating a door frame made of lignocellulosic materials and composite materials containing, among other things, a thermoplastic polymer, wood dust, resin, additives, and fillers, is known in application EP24205486.4, the priority of which is claimed.

[0004] The present utility model provides a door frame having a structure that is specifically adapted to work with door hardware, for example lock and hinge parts.

[0005] The object of the utility model is a door frame adapted to be mounted in a wall with a door opening, comprising three parts:

[0006] - a first strip,

[0007] - a main beam,

[0008] - a second strip,

[0009] in which the main beam constitutes the central part of the door frame and has two fixing slots on its two opposite sides, i.e. the first and second fixing slots, adapted to fix the first and second strips respectively,

[0010] in which the first strip, constituting the adjustment strip of the door frame, and the second strip, constituting the masking strip of the door frame, each having the shape of an angled piece with a masking arm and the second fixing arm,

[0011] wherein the first band and the second band are respectively fixed by their fixing arms in the fixing slots of the main beam,

[0012] wherein the main beam of the door frame has, on the inside, on the side of the second fixing slot, a reinforced structure,

[0013] characterized in that, with respect to the free end of the fixing arm of the second band, i.e. the end of the fixing arm which is not placed in the second fixing slot, the reinforced structure of the main beam begins at a distance of respectively:

[0014] - at least 45 mm, when the second strip is of the rebated type,

[0015] - at least 60 mm, when the second strip is of the type without a rebate,

[0016] and terminates at a distance of at most 100 mm from said free end of the fixing arm of the second band.

[0017] Preferably, in the reinforced structure area, the main beam has, in addition to the rear wall which, in the assembled state, is directed towards the wall, and in addition to the front wall which, in the assembled state, is directed towards the inside of the door opening, also two additional internal reinforcement walls, substantially parallel to the front and rear walls, each of these additional reinforcement walls having a thickness of 2 to 5 mm.

[0018] Preferably, in the area of ​​the reinforced structure, the main beam further has one, two or three auxiliary walls which are distributed uniformly over the length of the reinforced structure, which are substantially perpendicular to the front and rear walls of the main beam and which have a thickness of 2 to 4 mm.

[0019] Preferably, the second strip is a strip in a variant without a rebate whose fixing arm has a spacing thickening located between the end of the fixing arm of the second strip placed in the second fixing slot and the free end of the fixing arm of the second strip.

[0020] Preferably, the spacing thickening is located on the fixing arm of the second band in the area from 14 mm to 46 mm from the free end of the fixing arm of the second band.

[0021] Alternatively, the second strip is a strip in a variant with a rebate whose masking arm has a reinforced structure area extending over a length of up to 30 mm from the masking arm, measured from the end near the fixing arm of the second strip,

[0022] wherein within the reinforced structure zone are three to five reinforcing beams, in particular four reinforcing beams, which reinforcing beams extend substantially perpendicularly to the length of the cover arm of the second band,

[0023] in which each of these reinforcing beams has a thickness of 2 to 5 mm.

[0024] Preferably, substantially at the center of the reinforced structure of the masking arm of the second strip, there is also a longitudinal beam, extending inside the masking arm and substantially perpendicular to the reinforcing beams of the masking arm,

[0025] in which said longitudinal beam has a thickness of 1 to 3 mm. Brief description of the drawings

[0026] The object of this utility model will be described in more detail below in exemplary embodiments and with reference to the accompanying drawing, in which, in cross-section:

[0027] [Fig. 1] shows one embodiment of the first strip,

[0028] [Fig.2] shows an embodiment of the first strip,

[0029] [Fig.3] shows an embodiment of the second band, in a variant with rabbet,

[0030] [Fig.4] shows an embodiment of the second band, in a variant with rabbet,

[0031] [Fig. 5] shows an embodiment of the second band, in a variant without rabbet,

[0032] [Fig.6] shows an embodiment of the second band, in a variant without rabbet,

[0033] [Fig.7] shows embodiments of different dimensional variants of the main beam,

[0034] [Fig.8] shows embodiments of the finished door frame in different size variations, with a version with a rebate on the left and a version without a rebate on the right,

[0035] [Fig.9] shows an embodiment of a finished door frame installed on a wall with a visible leaf, in the variant without a rebate,

[0036] [Fig. 10] shows an embodiment of a finished door frame installed on a wall with a visible door leaf, in the variant with a rebate,

[0037] [Fig. 11] shows an example of a door frame according to the utility model, in a version with a rebate, with marked dimensions,

[0038] [Fig. 12] shows an example of a door frame according to the utility model, in a version without a rebate, with marked dimensions,

[0039] [Fig. 13] shows an example of a door frame according to the utility model, in a version with a rebate, with exemplary fittings mounted,

[0040] [Fig. 14] shows an example of a door frame according to the utility model, in a version without a rebate, with exemplary fittings mounted. Detailed description

[0041] The door frame, according to the present utility model, in the most general terms, has three main components – the first strip 1, the main beam 2, and the second strip, which exists in two variants – namely, the variant with a rebate 3a and the variant without a rebate 3b. The user is thus free to adapt the frame kit to The door can be configured in different door variants (with and without a rebate), using the same first strips 1 and main beams 2, and selecting only the second strip according to the desired variant with a rebate 3a or the variant without a rebate 3b. Therefore, door frame manufacturers only need to supply the relevant parts (in particular, the main beams 2) in the corresponding dimensional variants (see, for example, [Fig. 7] and [Fig. 8]), and the need to supply the main beams and one of the strips in two variants (with and without a rebate) is reduced to simply providing the given strips with or without a rebate.Thus, instead of the previously common arrangement of five pieces to create door frames for a given size, manufacturers can produce only four, the production effort, cost and material required to produce the strips being significantly less than the effort required to produce the main beams.

[0042] The aforementioned elements, i.e. the first strip 1, the main beam 2 and the second strip 3a, 3b, can be made of various materials (e.g. wood, plywood, chipboard, etc.), but because of the desired moisture resistance properties - they are made of composite-based materials, containing in their composition, among other things, wood dust, polymer material and fillers and additives.

[0043] The primary component of the composite material used is a thermoplastic polymer selected from a group including polyvinyl chloride (PVC), polypropylene (PP), polyethylene (PE), or polystyrene (PS), with a content ranging from 20% to 70% by weight; for example, it could be 45% by weight. The use of the aforementioned polymer contributes to increasing the material's strength through its resistance to various chemical agents, biocorrosion, and adverse environmental conditions (in particular, humidity). Furthermore, the material used is characterized by its plasticity, allowing the door frame material to be easily molded during production, thus enabling the creation of complex shapes or cross-sections with varied internal structures.

[0044] Plant-based materials containing lignin and cellulose (called lignocellulosic materials) constitute another component of the composite material used, and wood dust is an example of such a material used in a composite. The wood dust content can vary from 3% by weight to 50% by weight; for example, it can be 20% by weight. The use of wood dust allows for the utilization of wood waste and reduces production costs.

[0045] The use of a combination of thermoplastic polymers with a lignocellulosic material, on the one hand, provides a material that is not strictly a plastic material (which consumers often do not choose to buy because of prejudices against this type of material linked, among other things, to ecology), but a material which is partially made of wood while retaining many of the technical advantages of plastics, particularly with regard to, for example, water resistance, and will therefore be a suitable material for use in rooms with increased humidity such as bathrooms, saunas and laundry rooms; in addition, it is resistant to pests, fire and certain chemicals.

[0046] Another component of the composite material used is the filler, which can be calcium, generally in the form of calcium carbonate. The filler content can vary from 10% by weight to 60% by weight; for example, it can be 25% by weight. The use of such a filler increases the stability and density of the composite. Since calcium carbonate is a relatively inexpensive and widely available material, the use of calcium carbonate reduces production costs while still allowing for good mechanical properties in the final material.

[0047] The other components of the composite material are technological additives used. These additives may be modifiers, plasticizers, waxes, or colorants, among others. Their additive content may vary from 3% by weight to 20% by weight; for example, it may be 15% by weight.

[0048] In a preferred embodiment, the composite material from which the components of the door frame creation kit according to the utility model are made contains 45% by weight of polymer, 20% by weight of lignocellulosic material, 25% by weight of filler and 15% by weight of technological additives.

[0049] The door frame components have a non-accidental geometry that allows the user to conveniently mount them on the wall (in the doorway) to form a finished frame, and this design also offers advantages in terms of versatility of use and reduced number of parts that frame manufacturers have to supply.

[0050] The first strip 1 is in the form of an angled piece with a masking arm 11 and a second fixing arm 12. This first strip acts as an adjustment strip for the finished door frame. The adjustment function of the first strip 1 allows it to be adjusted during installation so that it adheres to the wall in the desired manner—by placing its fixing arm 12 sufficiently deep into the corresponding slot 21 in the main beam 2. This makes it possible to compensate for construction imperfections in the walls or partitions, compared to the main dimensional variants provided for the main beams 2 and possibly also for the first strips 1. The fixing arm 12 of the first strip 1, if a very precise adjustment is required, can be cut to size during installation, and the remainder can be mounted so that the first strip 1 is in full contact with the wall or so as to create the desired spacing.

[0051] The masking arm 11 of the first strip 1 covers the given edge of the door entrance and the materials and means of fixing with which the door frame, in particular its main beam 2, is installed in the door entrance.

[0052] The main beam 2 has two fixing slots on its two opposite sides, namely the first 21 and the second 22 fixing slots, adapted for attaching the fixing arms of the first 1 and the second 3a, 3b strips, respectively. The main beam has two sides, a left side and a right side, with a fixing slot on each side, and the middle portion of the beam extends between them. The main beams 2 also have a front surface and a rear surface. The front surface, which is visible in the assembled door frame, faces inward into the door opening; the rear surface, which remains hidden in the assembled frame, faces the wall.

[0053] In preferred embodiments, on one side of the main beam 2 there is a fixing groove in which a door bottom can be installed.

[0054] It is also possible to manufacture and assemble door frames without joints mounted in such a fixing groove, but for example by gluing joints on the main beam 2 along its entire length - thus, at the location of the fixing groove, the given main beam 2 would have a locally flat surface.

[0055] Preferably, the first 21 and second 22 fixing slots of the main beam 2 are adapted to mount the fixing arms 12, 32, 34 of the bands by tight fit, i.e. the width of the slots is slightly less than the width of said fixing arms.

[0056] Alternatively, the first 21 and second 22 fixing slots are as wide or slightly wider than the fixing arms 12, 32, 34 so that there is little or no spacing during assembly, so that additional adhesive or another type of bonding agent / glue can be used or the components can be assembled by high-temperature bonding.

[0057] Preferably, the first slot 21 has a depth provided such that the mounting arm 12 of the first fastener 1 mounted there can enter it entirely or be shortened and not reach the bottom of the slot, but in such a way that in such situations the contact area between the slot 21 and the mounting arm 12 of the first band 1 always ensures its stable attachment (so that, by itself or under the influence of a small force - it does not fall from the main beam 2).

[0058] The second strip 3a, 3b is the main element of the kit according to the utility model, which guarantees its versatility and allows for a reduction in the elements required to create door frames. In general, this strip has a structure (cross-sectional view) - similar to that of the first band 1, that is to say that it is presented in the form of an angled piece with two arms.

[0059] In both variants of the second strip 3a and 3b - one of the arms is a masking arm 31, 33 which, in the assembled state, performs the same functions as the masking arm 11 of the first strip 1. However, the internal structure of the masking arm 31, 33 of the second strip 3a, 3b changes depending on whether it is the strip in the variant with rebate 3a or in the variant without rebate 3b.

[0060] On the other hand, the fixing arm 32, 34 of the second band 3a, 3b is the element where the greatest design differences are observed, namely: - the fixing arm 32 in the variant with rebate - has, in principle, a simple design, which can be compared to a piece of relatively thin and flat material which is adapted to be placed in the second fixing slot 22 of the main beam 2; - the fixing arm 34 in the variant without rebate - is, in principle, longer than the fixing arm 32 of the variant with rebate, also has a structure which can be compared to a piece of thin and flat material, but this structure is locally enlarged and on the side of the masking arm 33 - a spacing thickening 35 is present.

[0061] Such a gap thickening 35 allows, when the door frame is to be used with a door without a rebate, sufficient space for this door to be flush with the outer surface of the masking arm 33 when closed (see [Fig. 9]). Furthermore, given the need to mount door accessories (lock parts, hinges, etc.) on this part of the door frame, such a gap thickening 35 advantageously influences the strength of the second strip 3b in this area and allows for the placement of screws, etc.

[0062] Preferably - such a spacing thickening 35 has a thickness corresponding to the thickness of the part of the main beam 2 between the second fixing slot 22 and the rear surface of the main beam, which provides a relatively uniform surface on the wall side.

[0063] It is preferable and desirable to reduce the weight of the elements used to create door frames, while maintaining their strength to a satisfactory degree - in such cases, the use of the composite material described above offers an advantage over wooden frames, because the parts of the frame according to this utility model can be formed relatively freely on the inside.

[0064] Preferably, some parts have a partially preserved solid structure (for example, the mounting arms 32 and 34), while other parts have a reduced-mass structure—in particular, a chambered structure (for example, the masking arms 31 and 33). Furthermore, parts of the main beam 2 may have a chambered structure - in particular the middle sections, which are not locally subjected to heavy loads (no hardware is mounted there, for example) and which serve mainly to provide adequate width to the main beams (see [Fig.7]).

[0065] Conversely, in order to allow at least a partial reduction in the weight of the given elements of the frame-building kit, but also to guarantee their corresponding high mechanical strength, parts such as the spacer thickening 35 and the masking arm portion 31, located on the side of the fixing arm 32, advantageously have a compacted chamber structure (see [Fig. 3], 4, 5 and 6). This compacted structure is significantly denser than the usual chamber structure that can be observed, for example, in the masking arm 11 of the first strip 1.

[0066] In addition to the compaction of the chambered structure of the strips, the main beam 2 advantageously has a compacted chambered structure (see [Fig. 7]), particularly over its entire front surface. Besides ensuring good strength and making the door frame resistant to damage that may occur in the event of an accidental impact on this part of the main beam 2, it turns out that thanks to the thickening of the chambered structure, it is possible to obtain a smooth outer surface through which the partitions of the inner chambered structure will not be visible (which is a problem in many structures made of plastic or composite materials that have a chambered structure).

[0067] In addition - the main beam 2 advantageously has a structure with compacted chambers at the places which form the sides of the first 21 and second 22 fixing slots - to guarantee adequate strength and bond strength with the fixing arms 12, 32, 34 of the bands.

[0068] Preferably - the main beam 2 also has a structure with compacted chambers inside the part immediately adjacent to the second fixing slot 22 to allow in this part a stable and robust fixing of the door hardware, such as the lock / hinge parts.

[0069] Although the Figures show cubic chamber structures (with cross-sections of squares and rectangles of varying sizes), it is evident that other shapes are possible in which internal chambers (both ordinary and in compacted structures) can be provided—circles, ovals, triangles, trapezoids, pentagons, hexagons, etc. The composite material used allows for great freedom in the design of these internal chambers, which do not even need to be of the same type (i.e., in certain embodiments—for example, in the beam). main 2, there may be compacted chambers in the shape of circles and larger chambers in triangular cross-section).

[0070] Preferably, the first band 1 is provided with at least one groove 13 on its fastening arm 12 extending along said first band 1. This groove 13 extends to a predetermined distance from the end of the fastening arm 12, marking a regular cutting line for the person fitting it, in case the first band 1 needs to be shortened by a given length. Although only one groove 13 is shown in the Figures, it is possible to provide more grooves 13 if necessary, for example, two, three, four, five or more grooves 13, marking given cutting lines.

[0071] Preferably, when there is only one groove 13 - this is spaced at a distance of between 10 mm and 30 mm, in particular 20 mm from the end of the fixing arm 12 of the first band 1, because this is the length by which the first band 1 most often has to be shortened.

[0072] To ensure that the utility model kit can be fixed to the most typical walls appearing on the European market, it is advantageous that its individual parts have the appropriate geometric dimensions, such as: - the width of the main beam 2 - between 70 mm and 340 mm, being in particular 86 mm, 126 mm, 166 mm, 206 mm, 246 mm, 286 mm or 326 mm; - the thickness of the main beam 2 - between 18 mm and 44 mm, being in particular 22 mm; - the length of the fixing arm 12 of the first band 1 - between 56 mm and 70 mm, being in particular 64 mm; - the length of the fixing arm 32 of the second attachment in variant 3a - being between 36 mm and 56 mm, being in particular 44 mm; - the length of the fixing arm 34 of the second band in the variant without groove 3b being between 52 mm and 70 mm, being in particular 60 mm; - the length of the masking arm 11, 31, 33 of the strips - being between 50 and 90 mm, being in particular 60 mm or 80 mm.

[0073] By producing a door frame creation kit, taking into account the proposed dimensional examples, it is possible to provide a range of products suitable for use in the majority of door openings encountered on the European market and to ensure that all door frames and door leaves of a given utility unit appear consistent with standard products currently available on the market.

[0074] In turn, the use of the described composite material for the described construction of frame elements ensures that these frames will be resistant to moisture and biocorrosion, thus eliminating the need to replace damaged frames after a short period of use.

[0075] The door frame according to the utility model is represented with dimensions in [Fig. 11] and 12, respectively in the variants with rebate and without rebate.

[0076] The common characteristic of the two variants of the door frame is that the reinforced structure 4 of the main beam 2 is provided in a specifically defined area in the assembled door frame, i.e.:

[0077] - the end of the reinforced structure 4 is at a distance of at most 100 mm, from preferably exactly 100 mm, measured from the free end of the fixing arm 32, 34 of the second band 3a, 3b (cf. [Fig. 11] and [Fig. 12]).

[0078] - the start of the reinforced structure 4 is planned at a distance of:

[0079] at least 45 mm, preferably exactly 45 mm, for the second band 3a in the variant with rebate, measured from the free end of the fixing arm 32 of the second strip 3a (cf. [Fig.11])

[0080] at least 60 mm, preferably exactly 60 mm, for the second band 3b in the variant without rebate, measured from the free end of the fixing arm 34 of the second band 3b (cf. [Fig. 12]).

[0081] In view of the above, the reinforced structure 4 of the main beam 2, which begins substantially near the second fixing slot 22, extends inside the main beam 2 for a length X (see [Fig. 11] and 12) of up to 55 mm (55 mm maximum for the variant with a rebate and 40 mm maximum for the variant without a rebate, respectively). This reinforcement zone of the main beam 2 allows for the mounting of the fittings 5 ​​and provides sufficient space for the two fittings 5 ​​mounted using one row of screws 51 placed in the main beam 2 (see [Fig. 13]) or two rows of screws 51 placed in the main beam 2 (see [Fig. 14]).

[0082] Preferably, the reinforced structure described above 4 of the main beam 2 provides an appropriate amount of material against which the threads of the fasteners of the fittings 51 can engage, to which the fittings 5 ​​are attached. According to the utility model, a preferred solution is to include two additional internal reinforcing walls 41 between the outer walls of the main beam 2 (i.e., the walls of which, in the mounted door frame, one is visible and oriented towards the inside of the door opening, and the other is invisible and oriented towards the wall). These additional reinforcing walls 41 are advantageously positioned substantially parallel to the aforementioned outer walls of the main beam 2, with a thickness ranging from 2 to 5 mm. This design allows a solid connection of the main beam 2 with the threads of the screws 51 of the fittings 5. Depending on the specific variant of the door frame, the thickness of these two internal reinforcing walls 41 can be respectively 2, 3, 4 or 5 mm.

[0083] Furthermore, in order to prevent deformation or even, in extreme cases, damage to the structure of the main beam 2 when tightening the screws 51 of the fittings 5, the main beam 2 of the door frame according to the utility model is advantageously provided with one, two or three auxiliary walls 42, which are distributed uniformly along the length of the reinforced structure 4 of the main beam 2. Such auxiliary walls 42 are formed substantially perpendicular to the outer (front and rear) walls of the main beam 2. Advantageously, such auxiliary walls 42 have a thickness of 2 to 4 mm, in particular 2, 3 or 4 mm.

[0084] The necessary and preferable characteristics described above of the door frame according to the utility model constitute a common part of the rebated and non-rebated door frames.

[0085] When, on the other hand, the door frame is in a version without a rebate (see [Fig. 12] and [Fig. 14]), the second strip 3b is a strip in a version without a rebate whose fixing arm 34 has a spacing thickening 35 located between the end of the fixing arm 34 of the second strip 3b placed in the second fixing slot 22 and the free end of the fixing arm 34 of the second strip 3b.

[0086] Preferably, to ensure good cooperation with the fittings 5, this spacer 35 is provided on the fixing arm 34 of the second band 3b in the area from 14 mm to 46 mm from the free end of the fixing arm 34 of the second band 3b. This allows easy positioning of the fixing elements 51 of the fittings 5 ​​by means of such a spacer 35.

[0087] In turn, when the door frame is in the variant with a rebate (see [Fig. 11] and [Fig. 13]), the second strip 3a is a strip in the variant with a rebate whose masking arm 31 has a reinforced structure area 36 extending over a length of up to 30 mm from the masking arm 31, measured from the end near the fixing arm 32 of the second strip 3a. Within the reinforced structure area 36 of the second strip 3a are three to five reinforcing beams 37, in particular four reinforcing beams 37, which reinforcing beams 37 extend substantially perpendicularly to the length of the masking arm 31 of the second strip 3a. These reinforcing beams 37 allow secure engagement of the threads of the fixing screws 51 of the fittings 5. Preferably, each of these reinforcing beams 37 has a thickness of 2 to 5 mm, in particular 2, 3 or 4 mm.

[0088] Preferably, in order to counter the internal deformations of the reinforcing beams 37 - substantially in the middle of the reinforced structure 36 of the masking arm 31 of the second band 3a, there is also a longitudinal beam 38 extending inside the masking arm 31 and substantially perpendicular to the reinforcing beams 37 of the masking arm 31. Said longitudinal beam 38 has a thickness of 1 to 3 mm, for example 2 mm.

[0089] List of digital references

[0090] 1 - first strip

[0091] 11 - masking arm of the first strip

[0092] 12 - first band fixing arm

[0093] 13 - groove

[0094] 2 - main beam

[0095] 21 - first fixing slot

[0096] 22 - second fixing slot

[0097] 3a - the second band, in the variant with rebate

[0098] 3b - the second band, in the variant without a rebate

[0099] 31 - masking arm, in the variant with rebate

[0100] 32 - fixing arm, in the variant with rebate

[0101] 33 - masking arm of the second strip, in the variant without rebate

[0102] 34 - fixing arm of the second band, in the variant without rebate

[0103] 35 - spacing thickening

[0104] 36 - reinforced structure of the second band

[0105] 37 - Reinforcing beam of the reinforced structure of the second band

[0106] 38 - longitudinal beam of the reinforced structure of the second band

[0107] 4 - reinforced structure of the main beam

[0108] 41 - internal reinforcement wall of the reinforced structure of the main beam

[0109] 42 - auxiliary wall of the reinforced structure of the main beam

[0110] 5 - fittings

[0111] 51 - screws / bolts / fastening elements for fittings

Claims

Demands

1. A door frame adapted for mounting in a wall with a door opening, comprising three parts: - a first strip (1), - a main beam (2), - a second strip (3a, 3b), in which the main beam (2) constitutes the central part of the door frame and has two fixing slots (21, 22) on its two opposite sides, namely the first (21) and second (22) fixing slots, adapted to fix thereon respectively the first (1) and the second (3a, 3b) strips, in which the first strip (1), constituting the adjustment strip of the door frame, and the second strip (3a, 3b), constituting the masking strip of the door frame, each having the form of an angled piece with a masking arm (11, 31, 33) and the second fixing arm (12, 32, 34), in which the first strip (1) and the second strip (3a, 3b) are respectively fixed by their fixing arms (12, 32, 34) in the fixing slots (21, 22) of the main beam (2),in which the main beam (2) of the door frame has, on the inside, on the side of the second fixing slot (22), a reinforced structure (4), characterized in that, with respect to the free end of the fixing arm (32, 34) of the second strip, i.e. the end of the fixing arm (32, 34) which is not placed in the second fixing slot (22), the reinforced structure (4) of the main beam (2) starts at a distance of respectively: - at least 45 mm, when the second strip (3a) is of the rebate type, - at least 60 mm, when the second strip (3b) is of the non-rebate type, and ends at a distance of at most 100 mm from said free end of the fixing arm (32, 34) of the second strip (3a, 3b).

2. Door frame according to claim 1, characterized in that in the reinforced structure zone (4), the main beam (2) has, in addition to the rear wall which, in the assembled state, is directed towards the wall, and in addition to the front wall which, in the assembled state, is directed towards the interior of the door opening, also two additional internal reinforcing walls (41), substantially parallel to the front and rear walls, each of these additional reinforcing walls (41) having a thickness of 2 to 5 mm.

3. Door frame according to claim 2, characterized in that in the area of ​​the reinforced structure (4), the main beam (2) further has one, two or three auxiliary walls (42) which are distributed uniformly over the length of the reinforced structure (4), which are substantially perpendicular to the front and rear walls of the main beam (2) and which have a thickness of 2 to 4 mm.

4. Door frame according to claim 2 or 3, characterized in that the second strip (3b) is a strip in a variant without rebate whose fixing arm (34) has a spacing thickening (35) located between the end of the fixing arm (34) of the second strip (3b) placed in the second fixing slot (22) and the free end of the fixing arm (34) of the second strip (3b).

5. Door frame according to claim 4, characterized in that the spacing thickening (35) is located on the fixing arm (34) of the second strip (3b) in the area from 14 mm to 46 mm from the free end of the fixing arm (34) of the second strip (3b).

6. Door frame according to claim 2 or 3, characterized in that the second strip (3a) is a strip in a variant with a rebate, the masking arm (31) having a reinforced structure area (36) extending over a length of up to 30 mm from the masking arm (31), measured from the end near the fixing arm (32) of the second strip (3a), in which within the reinforced structure area (36) are three to five reinforcing beams (37), in particular four reinforcing beams (37), which reinforcing beams (37) extend substantially perpendicularly to the length of the cover arm (31) of the second strip (3a), in which each of these reinforcing beams (37) has a thickness of 2 to 5 mm.

7. Door frame according to claim 6, characterized in that substantially at the center of the reinforced structure (36) of the masking arm (31) of the second strip (3a) there is further a longitudinal beam (38) extending inside the arm of masking (31) and substantially perpendicular to the reinforcing beams (37) of the masking arm (31), in which said longitudinal beam (38) has a thickness of 1 to 3 mm.

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