SK1482023U1 - Improved inspection trapdoor - Google Patents

Abstract

An inspection trapdoor comprises: a fixed frame (TF), a movable frame (TM), a panel connected to the movable frame (TM), and connection means (5, 6) for connecting the movable frame (TM) to the fixed frame (TF); wherein at least one of said frames (TM, TF) comprises at least three sections (1, 2) with ends (11, 21) cut at 90°, and at least three corner pieces (3, 4), wherein each corner piece connects two adjacent sections (1, 2) in an arrangement wherein they are disposed transversally; the corner piece (3, 4) comprises a central portion (30, 40) suitable for abutting against the ends (11, 21) of two adjacent sections (1, 2) and two lateral inserts (31, 41) that protrude from the central portion (30, 40) in such a way to be coupled with the sections (1, 2); wherein the central portion (30, 40) and the lateral inserts (31, 41) of the corner piece (3, 4) are made in one piece.

Description

The field of technology

The presented technical solution concerns improved inspection doors. As is well known, inspection doors are usually installed with openings made in the walls in such a way as to allow inspection of the compartment located behind the wall.

It should be noted that in this specification the term "wall" refers arbitrarily to vertical walls and ceilings or floors.

Current state of the art

In order to better understand the problems and disadvantages of the prior art, the description of inspection doors according to the prior art continues with reference to the following images defined as PRIOR ART, where:

fig. 1 is a front view of a prior art inspection door;

fig. 2 is a schematic view of part of the fixed frame of the inspection door from fig. 1 and on part of the movable frame of the inspection door from fig. 2, which show parts of the sections which are discarded for the 45° cut;

fig. 2A is a schematic side view of two sections placed one on top of the other;

fig. 2B is a top view of the two sections of FIG. 2A; Fig. 2B shows a 45° section starting from the corner of the section;

fig. 2C shows two sections from fig. 2B placed next to each other and not on top of each other; Fig. 2C shows a portion of the top and a portion of the bottom removed after a 45° cut with the sections placed one on top of the other;

fig. 3 and 3A are views of two prior art inspection doors with the sections joined using two different connection modes.

Referring to the images above, a conventional inspection door includes:

- a frame 91 suitable for attachment to the wall in accordance with the hole in the wall;

- a movable frame 92 located inside a fixed frame 91, in a movable manner between an open position and a closed position;

- a panel (not shown in the attached figures) internally connected to the movable frame 92, and

- connecting means (not shown in Fig. 3 and 3A) for movable connection and support of the movable frame 92 with respect to the fixed frame 91.

Each frame 91, 92 consists of four sections 910, 920.

The ends of each section 910, 920 are cut at a 45° angle such that the end edge of the section 910, 920 matches and abuts the end edge of the section 910, 920 in an adjacent position.

According to the first method of connecting the sections, which is shown in fig. 3, the connection between the two sections 910, 920 is achieved by means of metal corner pieces 931, each of which contains two wings, each wing being fixed to the section by means of screws 93v.

According to the second method of connecting sections, which is shown in fig. 3A, the connection between the two sections 910, 920 is achieved by means of metal corner brackets 932, each of which includes two wings inserted in the longitudinal notches of the two sections in an adjacent position. In this case, the connection of each wing with the corresponding part is achieved by punching.

Despite the fact that similar inspection doors have been very well received by the market so far, it is evident that they are affected by some disadvantages.

The first disadvantage occurs when cutting sections to the required size. In fact, cutting sections at a 45° angle is an extremely complicated and delicate operation and therefore extremely prone to error.

Additionally, dimensional tolerances are extremely complicated to manage when section ends are cut at a 45° angle. More specifically, said inspection doors are not universal, that is, each outer fixed frame 91 matches a single inner movable frame 92 and are therefore not interchangeable. In other words, between inspection hatches of the same size, the movable frames 92 cannot be interchanged due to the presence of minor imperfections that prevent interchangeability between the movable frames 92 of the same size.

Another disadvantage that worsens the inspection door according to the prior art, moreover, concerns the waste of material in the production of sections 910, 920.

In fact, according to the manufacturing process of the sections 910, 920, the sections are first formed, and then the ends of the section are cut at an angle of 45°, according to the previously calculated values.

Cutting sections at an angle of 45° necessarily involves a waste of material, which can usually range from a minimum of 5% to a maximum of 20%, depending on the size of the inspection door being produced and the thickness of the section. In fig. 2 is the part of the section 910, 920 that is lost, indicated by a dotted line.

SK 148-2023 U1

In addition, due to the 45° cut, the operator cannot simultaneously cut multiple sections of the same size placed on top of each other.

Such a disadvantage will become clearer with reference to fig. 2A, 2B and 2C.

Generally speaking, each section 910, 920 has a vertical wing which does not allow the sections to be stacked perfectly vertically, but rather generates a staggered effect as shown in FIG. 2A. The two sections 910', 910 of the fixed frame 91 are shown in FIG. 2A, but the same would apply to the movable frame sections 92.

Such a staggered arrangement of the sections 910', 910 does not allow the user to simultaneously cut the sections 910', 910 in the same way with a single cutting operation.

As an example, referring to FIG. 2B and 2C, when making a 45° cut starting from edge S10' of the bottom portion 910', the bottom portion 910' will be cut straight while the top portion 910' will be cut at a 45° angle, thereby losing the portion of section t10' that is straight proportional to the thickness of the vertical wing. The greater the thickness of the wing, the greater the portion t10 of the top section lost relative to the bottom during the 45° cutting operation. Therefore, the upper part of the 910 will be shorter than the lower part of the 910.

Because of this inconvenience, it will be necessary to cut one section after another, which requires a long time to produce such inspection doors.

Such a long production time is very inconvenient in the large production processes of such inspection doors.

Another disadvantage of inspection doors according to the current state of the art relates to the fact that, despite the precision and expertise of the operator when assembling the frames 91, 92, these frames are often equipped with irregularities (due to imperfect alignment of the sections), which strongly affect the aesthetics of the final inspection door.

In addition, the corners of the inspection door are made as sharp corners, which are extremely dangerous for the operator when mounting the inspection door on the wall.

W02020120939A1 describes a hatch, mainly for use in openings in the floor of buildings under construction. The cover includes an inner frame that is provided with smaller dimensions than the opening and is inserted into the opening, and an outer frame that has larger dimensions than the opening and rests on the floor. The hatch also includes two door panels that are hinged to the outer frame and can be moved between the closed and open positions.

Each frame contains frame elements that define a rectangular frame. Each frame member has a square or rectangular cross-section and each side is provided with a longitudinal channel that extends along the entire length of the frame member. The frame member is cut at the ends at an angle of 90° in such a way that its end surfaces are arranged perpendicular to the side surfaces.

The frame members of the frame are connected by means of a first guide element inserted into the channel of the frame member and a second guide element inserted into the channel of the second frame member, wherein said guide elements are mutually connected by means of threaded elements.

Mainly, one of the two guide elements is equipped with a threaded hole, while the other guide element is equipped with a screw suitable for connection with the threaded hole of the second guide element. With regard to the above, for the connection of two frame members, it is necessary to place each sliding element near the end of the frame member so that the screw and the threaded hole are aligned. Then, using a suitable tool (for example, a screwdriver), the screw is screwed into the threaded hole so that the two guide elements come together and connect the two frame elements.

Said guide elements are connected by means of threaded elements and are also used to connect the inner frame to the outer frame.

Such a hatch is affected by certain disadvantages.

Assembling the hatch, which is performed by connecting the guide elements using threaded elements, is complicated and time-consuming for the operator.

In addition, the hatch is dangerous because the outer frame may have edges or protrusions that could injure the operator.

The presence of such edges or protrusions is caused by the structural arrangement of the frame, according to which at least four of the end faces of the four frame members are exposed outwards. In fact, the end faces of the frame members that are exposed to the outside may have frays or sharp parts that can injure the user.

In addition, unless the end face is perfectly aligned with the side face of an adjacent frame member, an edge or unevenness will be created between the side face and the end face, risking injury to the operator.

DE202006004357U1 describes a cover for a light and/or ventilation shaft. Such a cover includes a frame with four bars and four connectors. Each connector connects two adjacent bars at a 90° angle.

Each connector contains:

- a square body having two channels located at right angles;

- two screws, each of which is inserted into one of the mentioned channels and fits into the threaded seat

SK 148-2023 U1 formed at the end of the rod.

Therefore, in order to connect two adjacent rods, it is necessary to place the two rods in a vertical position, place the square body between the two rods so that the channels are aligned with the threaded seat, insert the screws into the channels, and finally screw the screws in the threaded seats. Obviously, such an operation is quite complicated and slow to perform.

The essence of the technical solution

The purpose of this technical solution is to design an inspection door that is effective, simple and inexpensive to manufacture.

Another purpose of the presented technical solution is to design an inspection door where it is no longer necessary to cut sections at an angle of 45°.

Another purpose is to provide an inspection door that is reliable and suitable for preventing injury to the operator.

These objectives are achieved in accordance with the technical solution with the features indicated in the attached independent claim 1.

Advantageous embodiments follow from the dependent claims.

The inspection door according to the technical solution is defined by claim 1, where the inspection door contains:

- a solid frame suitable for attachment to the wall in accordance with the hole in the wall;

- a movable frame placed inside a fixed frame,

- a panel attached to said movable frame in such a way as to close said opening, a

- movable connecting means for connecting the movable frame to the fixed frame so that the movable frame can be moved from an open position to a closed position

- wherein at least one of said frames comprises at least three sections provided with ends cut at an angle of 90° and at least three corner pieces, each corner piece connecting two adjacent sections in an arrangement where they are located transversely;

- said corner part includes a central part suitable for fitting on said ends of two adjacent sections and two side inserts which protrude from the central part so as to be connected to said sections; whereas

- the central part and the side inserts of the corner part are made of one piece.

Preferably said fixed frame comprises four sections and four corner pieces; each corner part of the fixed frame connects two adjacent sections; while each corner part has lateral inserts in a perpendicular position.

Furthermore, the mentioned corner part is advantageously made of plastic material or of aluminum cast under pressure or of composite material.

Advantageously, the side inserts of the corner part have the shape of a rectangular plate.

Preferably, each side insert has recessed saddles, with part of the section connected by deformation.

Preferably, each section has a C-shaped cross-section which defines a longitudinal channel open at the ends of the section and said corner piece insert is inserted from the ends of the section into the longitudinal channel.

Advantageously, said longitudinal channel is defined by two opposite protrusions; wherein each longitudinal projection is deformed in such a way as to define a projection which projects into the longitudinal channel to engage the recessed seat of the corner piece side insert.

Preferably, the central part of the corner part has a quadrangular shape and contains two outer sides and two inner sides equipped with said inserts in a protruding position; said middle part is located outside the section in such a way that it forms a corner of the frame.

Preferably, the outer sides of the central part of the corner part of the fixed frame are connected by a curved section in such a way that the inspection door is free of sharp corners from the outside.

Preferably, the inspection door includes securing means suitably configured to secure the movable frame relative to the fixed frame in the closed position.

Preferably, the security means are located on the corner parts located in the corresponding two adjacent corners of the inspection door.

Advantageously, the mentioned connecting means are placed on the corner parts located in the corresponding two adjacent corners of the inspection door.

Preferred security means include:

- security device, integral with the corner part of the movable frame; said securing means is arranged to define a recess in the cutout;

- latch safety device integral with the corner part of the fixed frame; mentioned

SK 148-2023 U1 latch safety device includes a fixed part and a movable part, which is suspended from the fixed part and has a stopper suitable for placement inside the recess in the cut-out.

Advantageously, the securing means is formed as one piece with the corner part of the movable frame; said locking device is mounted on a support formed in one piece with the corner part of the fixed frame.

Advantageously, the inspection door comprises end stop means located between the corner part of the movable frame and the corner part of the fixed frame and suitable for stopping the movement of the movable frame when the movable frame is moved from the closed position to the open position.

Preferred end stop means include:

- the first eyelet connected to the corner part of the fixed frame;

- the second eyelet connected to the corner part of the movable frame; a

- chain connected with the first loop on one side and with the second loop on the other side.

- Advantageously, the first eyelet is made of one piece with the corner part of the fixed frame and said second eyelet is made of one piece with the corner part of the movable frame.

- Advantageously connecting means include:

- a first element having a first part made of one piece with the corner part of the fixed frame and a second part that extends beyond the corner part of the movable frame and engages the corner part of the movable frame;

- a second element having a first part made of one piece with the corner part of the movable frame and a second part which extends beyond the corner part of the fixed frame and engages the corner part of the fixed frame.

- Preferably, each section contains two wings in an orthogonal position, namely:

- a first C-section wing having said longitudinal channel; a

- a second wing that protrudes from one side of said first wing in the opposite direction with respect to said longitudinal channel.

Preferably, the central part of the corner part of the movable frame contains two retaining edges located on the two outer sides of the central part; where the second wing of the movable frame section is placed next to itself and rests on the retaining edge of the central part of the corner part of the movable frame such that all the retaining edges and the second wings of the movable frame sections define a single outer annular edge of the movable frame.

Preferably, the height of the second wing of the movable frame section is the same as the height of the retaining edge, so that the upper edges of the second wing and the adjacent retaining edges are in one plane.

Preferably, said movable frame and panel are made of one piece, thus defining a single cover door.

Overview of images on drawings

For the sake of clarity, the description of the inspection door continues according to the technical solution with reference to the attached images, which have an exclusively illustrative and non-limiting value, where:

fig. 1 is a front view of a prior art inspection door;

fig. 2 is a schematic view of part of the fixed frame and part of the movable frame, showing the parts that are removed after making a 45° cut;

fig. 2A is a schematic side view of two sections placed one on top of the other;

fig. 2B is a top view of the two sections of FIG. 2A; fig. 2B shows a 45° cut from the cutting edge;

fig. 2C is a view of two sections of FIG. 2B placed next to each other instead of on top of each other; fig. 2C shows a portion of the top and portion of the bottom removed after a 45° cut with the sections placed one on top of the other;

fig. 3 and 3A are views of two prior art inspection doors where the sections are connected using two different types of connections;

fig. 4 is a front view of the inspection door according to the technical solution;

fig. 4A is an axonometric front view of the inspection door according to the technical solution;

fig. 5 is a rear view of the inspection door according to the technical solution;

fig. 5A is an axonometric rear view of the inspection door according to the technical solution;

fig. 6 is an axonometric schematic view of the corner piece of the movable frame of the inspection door according to the technical solution when viewed from the front;

fig. 6A is a view of the corner portion shown in FIG. 6;

fig. 7 is an axonometric schematic view of the corner piece of the fixed frame of the inspection door according to the technical solution when viewed from the front;

fig. 7A is a top view of the corner piece shown in FIG. 7;

fig. 8 is an axonometric schematic view of part of the movable frame:

SK 148-2023 U1

fig. 9 is a schematic axonometric view of a portion of a fixed frame;

fig. 10 is an enlarged schematic view of the manner in which the corner piece is connected to the frame section;

fig. 10A is a cross-sectional view of the corner piece and the cross-section of FIG. 10, in section along plane XX;

fig. 11 and 11A are two rear axonometric views of a corner piece of a fixed frame and a movable frame where end stop means and securing means are provided;

fig. 11B is identical to FIG. 11A, with the exception of the embodiment of the latching safety device attached to the corner part of the fixed frame;

fig. 11C and 11D are rear axonometric views of a fixed frame corner portion and a movable frame corner portion, respectively, where end stop means and locking means are provided;

fig. 12 shows an alternative version of the inspection door according to the technical solution.

Implementation examples

With reference to fig. 4 to 11D are described inspection doors according to the technical solution.

With reference to fig. 4, 4A, 5 and 5A, inspection doors according to the technical solution contain:

- solid TF frame suitable for fixing to the wall in accordance with the hole in the wall;

- a movable TM frame located inside a fixed TF frame,

- a panel (not shown in the attached images) internally connected to the movable frame TM so as to close the opening;

- connecting means 5, 6 for connecting the movable frame TM to the fixed frame TF in such a way that the movable frame TM can move between an open position, wherein the movable frame TM is tilted with respect to the fixed frame TF, and a closed position, wherein the movable frame TM lies in the same plane as the solid TF frame.

The trap door has a quadrangular shape with four corners Q1, Q2, Q3 and Q4.

Specifically, the fixed frame TF comprises four sections 2 with ends 21 cut at an angle of 90° and four corner pieces 4, each of which connects two sections 2 in an adjacent position. Similarly, the movable frame TM comprises four sections 1 with ends 11 cut at an angle of 90° and four corner pieces 3, each of which connects two sections 1 in an adjacent position.

With reference to fig. 6, 6A, 7 and 7A, each corner part 3, 4 comprises a central part 30, 40 suitable for abutting on said ends 11, 21 of two adjacent sections and two side inserts 31, 41 which project from the central part 30, 40 so that to be connected to said sections 1, 2. Since the inspection door is square or rectangular in shape, the two side inserts are perpendicular to each other and the two adjacent sections are orthogonal and placed at right angles.

The central part 30, 40 and the side inserts 31, 41 of each corner part 3, 4 are machined as one part.

Preferably, the mentioned corner parts 3, 4 are made of plastic material or cast aluminum or composite material, such as polyamide PA6 filled with glass and/or carbon fibers, or polyarylamide (Kitan X).

Each corner part 3, 4 and each section 1, 2 comprises a front face suitable for being seen and a rear face which is positioned in an opposite position to said front face and is suitable for facing a chamber having be controlled.

The coupling means 5, 6 are configured to allow the movable frame TM to move relative to the fixed frame TF, whereby the movable frame TM would be disconnected from the fixed frame TF.

With reference to fig. 5 and 5A are connecting means 5, 6 located on corner parts 3, 4 located in two adjacent corners Q3, Q4 of the control door. Said connecting means 5, 6 are located on the back side of the corner parts 3, 4.

Each connecting means 5, 6 contains two elements, namely:

- the first element 6, which has a first part 61 made in one piece with the corner part 4 of the fixed frame TF, and a second part 62 extending over the corner part 3 of the movable frame TM and engaging the corner part 3 of the movable frame TM;

- the second element 5 having a first part 51 made of one piece with the corner part 3 of the movable frame TM and the second part 52 extending over the corner part 4 of the fixed frame TF and engaging the corner part 4 of the fixed frame TF.

Advantageously, the second element 5 is essentially L-shaped, and therefore the two parts 51 and 52 of the second element 5 are perpendicular.

The two elements 5 and 6 operate in such a way that the two frames TM, TF are never disconnected, even when the movable frame moves relative to the fixed frame.

With reference to fig. 6, 6A, 7 and 7A, the central part 30, 40 of each corner part 3, 4 has a quadrangular shape

SK 148-2023 U1 and includes two outer sides 302, 402 perpendicular to each other and two inner sides 301, 401 perpendicular to each other, from which protrude the mentioned side inserts 31, 41, which have the shape of a rectangular plate. Each insert 31, 41 has embedded beds 32, 42, while part of the section 1, 2 is connected by deformation.

With reference to fig. 7 and 7A, the outer sides 402 of the center part 40 of the corner part 4 of the fixed frame TF are connected by the curved part 40t so that the inspection door has no sharp edges on the outside. In this way, the inspection door is not dangerous for the user when mounting the inspection door on the wall.

With reference to fig. 8 and 9, each section 1, 2 has a C-shaped cross-section defining a longitudinal channel 10, 20 which extends along the entire length of the section 1, 2 and is open at both ends of the section 11, 21.

The insert 31, 41 is inserted from the ends 11, 21 of the section into the longitudinal channel 10, 20, while the central part 30, 40 remains outside the section 1, 2, thus forming a corner of the frame TM, TF. The side insert 31, 21 is completely inserted into the longitudinal channel 10, 20 so that the end 11, 21 of the section 1, 2 rests on the inner side 301, 401 of the central part 30, 40 of the corner piece 3, 4.

Still referring to fig. 8 and 9, each section 1, 2 comprises two opposite longitudinal projections 18, 28 which define a longitudinal channel 10, 20.

With reference to fig. 10 and 10A, to connect the insert 31, 41 to the section 1, 2 in the adjacent position, it is first necessary to insert the insert 31, 41 into the longitudinal channel 10, 20 of the section 1, 2 (see Fig. 10) and then pierce the longitudinal tabs 18, 28 so that said longitudinal tongues 18, 28 are deformed at least at one point and form a projection d which protrudes into the longitudinal channel 10, 20 and is connected to the recessed seats 32, 42 of the side insert 31, 41 (see Fig. 10A).

With reference to fig. 6 and 6A, the central part 30 of the corner part 3 of the movable frame TM includes two retaining edges 35 located on the two outer sides 302 of the central part 30.

With reference to fig. 7 and 7A, the middle part 40 of the corner part 4 of the fixed frame TF contains two posts 45 perpendicular to each other and positioned in accordance with the angle defined by the two inner sides 401 of the middle part 40.

Let's go back to fig. 8 and 9, each section 1, 2 preferably comprises two mutually perpendicular wings, namely:

- a first wing 14, 24 with a C-shaped section having said longitudinal channel 10, 20; a

- a second wing 15, 25 protruding from one side of said first wing 14, 24 in the opposite direction with respect to the longitudinal channel 10, 20.

The second wing 15 of the section 1 of the movable frame TM is arranged side by side and rests on the retaining edge 35 of the central part 30 of the corner piece 3 of the movable frame TM so that all the retaining edges 35 and the second wings 15 of the sections 1 of the movable frame TM define a single outer annular edge of the movable frame TM.

Advantageously, the height of the second wing 15 of section 1 of the movable frame TM is the same as the height of the retaining edge 35, so that the upper edges of the second wing 15 and the retaining edge 35 in the adjacent position are mutually in the same plane.

The second wing 25 of the section 2 of the fixed frame TF is arranged on the sides and rests on the adjacent post 45 of the central part 40 of the corner part 4 of the fixed frame TF so that the posts 45 and the second wings 25 of the sections 2 of the fixed frame TF define a single inner annular edge of the fixed frame TF.

Advantageously, the height of the second wing 25 of section 2 of the fixed frame TF is the same as the height of the column 45, so that the upper edges of the second wing 25 and the adjacent column 45 are mutually aligned.

let's go back to fig. 5 and 6, the end stop means 70, 71, 72 are arranged in accordance with the corners Q1, Q2, opposite to the corners Q3, Q4, where the connecting means 5, 6 are arranged, said end stop means 70, 71, 72 are suitable for stopping the movement of the moving frame TM when the moving frame TM moves from the closed position to the open position.

Said end stop means 70, 71, 72 are provided between two adjacent corner parts 3, 4 of the movable frame and the fixed frame in accordance with the rear surfaces of said corner parts 3, 4.

With reference to fig. 11, end stop means 70, 71, 72 contain:

- the first eyelet 71 connected to the corner part 4 of the fixed frame TF;

- the second eyelet 72 connected to the corner part 3 of the movable frame TM; a

- a chain 70 connected to the first link 71 on one side and to the second link 72 on the other side.

The chain 70 includes two hooks (specifically two spring latches), one of which is attached to the first eyelet 71 and the other hook is attached to the second eyelet 72.

Chain 70 further includes a wire attached to two hooks.

Preferably, the first eyelet 71 is made of one piece with the corner part 4 of the fixed frame TF, and said second eyelet 72 is made of one piece with the corner part 3 of the movable frame. TM.

With reference to fig. 5, 11, 11A, 11B, 11C and 11D, in accordance with the corner Q1, Q2, where the end stop means 70, 71, 72 are arranged, the securing means 81, 83 are adapted to stop the movable frame TM with respect to the fixed frame TF in closed position. Also, the securing means 81, 83 are arranged in accordance with the rear face of the corner parts 3, 4.

SK 148-2023 U1

Said security means 81, 83 include:

- the securing element 81, which is integral with the corner part 3 of the movable frame TM and is configured to define a recess 82 in the cutout:

- the latch securing device 83, which is shown exclusively in fig. 11B, which is integral with the fixed corner piece 4; said security device 83 includes a fixed part 831 and a movable part 832, which is suspended on the fixed part 831 and is equipped with a stop 830 suitable for fitting into the recess 82 in the cut-out.

Preferably, the securing element 81 is made in one piece with the corner part 3 of the movable frame TM.

The latch securing device 83 includes retaining means (not shown in the attached figures) connected to the fixed part 831 on one side and to the movable part 832 on the other side, which operate on the movable part 832 in such a way that the latch 830 fits into the recess 82 in the cut-out, when the movable frame TM is in the closed position, allowing the movable frame TM to be released from the closed position, when said movable frame TM is pushed by the user into the open position with sufficient force to overcome the resistance of the securing means. By way of example, said securing means may consist of a torsion spring with one end connected to the movable part 832 of the securing device 83 and one end connected to the fixed part 831 of the securing device 83.

Therefore, it is understood that in order to move the movable frame TM from the closed position to the open position, it will be necessary to push the movable frame TM (or center panel) with sufficient force to overcome the resistance provided by the retaining means in order to release the firing pin 830 from the recess 82 in the cutout.

With reference to fig. 11, 11A, 11B and 11D, said latch securing device 83 is mounted on a supporting element 85 formed in one piece with the corner piece 4 of the fixed frame TF.

Said support element 85 consists of a wall that vertically protrudes from the rear side of the corner part 4 of the fixed frame TF and includes an inner face 851 facing the inside of the inspection door, an outer face 852 facing the opposite side and two side walls 853. The inner face 851 is equipped with a recessed seat , which is suitably configured to accommodate the latch locking device 83. The fixed part 831 of the locking device 83 is attached to the support member 85 by means of fixing screws FF inserted into the holes of the fixed part 831 and inserted into the holes sw drilled in the support member 85.

The groove 86 is made at the base of the supporting member 85, into which the tab 28 of one of the sections 2 of the fixed frame TF is inserted.

Preferably, the first eyelet 71 is made on the side surface 853 of the supporting wall 85, while the second eyelet 72 is made on one of the inserts 31 of the corner piece 3 of the movable frame TM.

Again referring to fig. 11 to 11D, the reinforcing partitions uf, um are preferably located on the back side of each corner part 3, 4 and are placed astride between the central part 30, 40 and the inserts 31, 41.

As a result of the previous description, the advantages of this utility model seem obvious. The benefits listed are as follows:

- waste or unusable residues are reduced compared to the state of the art; especially with inspection doors according to the technical solution, practically no waste or unusable residues are created during the cutting of profiles, because it is no longer necessary to cut the ends of the profiles at an angle of 45°;

- dimensional tolerances are easily achievable; more precisely, due to the 90° cut of the ends 11, 21 of section 1, 2, doors of the same size are completely identical; therefore, as long as more than one inspection door of the same size is installed, the TM movable frames are interchangeable:

- higher safety compared to inspection doors according to the prior art, this advantage is due to the absence of sharp edges on the outside of the solid TF frame;

- highly flexible design, which means that the corner parts 3, 4 can be made of plastic or die-cast aluminum; in both cases, a simple modification of the mold used for production allows them to be adapted to any variant of the inspection door;

- better aesthetics compared to inspection doors according to the current state of the art; in fact, the sections 1, 2 and the corner parts 3, 4 are perfectly aligned, and therefore, unlike the prior art, the TM, TF frames are not equipped with steps, which can be extremely dangerous for operators, in addition to being aesthetically unpleasant;

- in addition, the 90° cut allows simultaneous cutting of several sections placed on top of each other, in the same way and with the same dimensions; the possibility of simultaneous cutting of several sections located on top of each other makes the production of inspection doors according to the technical solution significantly faster compared to inspection doors according to the current state of the art.

Furthermore, when comparing the inspection door according to the technical solution with the inspection door described in

SK 148-2023 U1

W02020120939A1 and DE202006004357U1, inspection doors according to the technical solution are:

- easier to assemble than other inspection doors, because they do not require the use of screws or multiple elements for connection and only require the connection of the corner part 3, 4 obtained in one piece with two adjacent sections 1, 2;

- more universal than other inspection doors, because the corner part 3, 4 obtained from one piece can be equipped with functional elements, such as connecting means 5, 6, suspension means 81, 83 and eyelets 71, 72 of end stop means;

- more secure than the inspection door described in W02020120939A1, because the ends of the sections 11, 21 (the part of the section that may have frays or imperfections due to cutting) abut the inner sides 301, 401 of the central part 30, 40 of the corner parts 3, 4, and therefore not are visible or exposed and there is no danger that the user could touch or come into contact with them and cause injury or lacerations.

Numerous variants and detailed modifications can be made on the presented embodiment of the technical solution, within the reach of an expert in the field, but within the scope of the technical solution, as expressed in the appended claims.

As an example, although the trapdoor has been shown with a quadrangular shape, the trapdoor can be any other shape such as triangular, pentagonal, hexagonal, and the like.

In the case of a triangular shape, each frame TM, TF will have three sections 1, 2 with ends 11, 21 cut at an angle of 90° and three corner pieces 3, 4. In this case, each corner piece will connect two adjacent sections 1, 2 in an arrangement , where the two sections 1, 2 are mutually transverse but not orthogonal.

Finally, although fig. 4 to 11D show an inspection door with a fixed frame TF and a movable frame TM composed of sections and corner pieces, it would not change the purposes to achieve the objectives of the utility model if, instead of being composed of sections and corner pieces, the movable frame was made of one piece with a center panel and thus defined a single monolithic cover door E that moves relative to the fixed frame TF. Such an alternative version is shown in fig. 12.

Claims (22)

1. An inspection door comprising: a fixed frame (TF) suitable for attachment to a wall in accordance with an opening in the wall; a movable frame (TM) located inside a fixed frame (TF), a panel connected to said movable frame (TM) in such a way as to close said opening, and movable connecting means (5, 6) for connecting the movable frame (TM) to the fixed frame (TF) so that the movable frame (TM) can be moved from the open position to the closed position, while at least one of said frames (TM, TF) comprises at least three sections (1, 2) equipped with ends (11, 21) cut at an angle 90° and at least three corner pieces (3, 4), each corner piece connecting two adjacent sections (1, 2) in an arrangement where they are placed transversely; said corner part (3, 4) comprises a central part (30, 40) suitable for fitting onto said ends (11, 21) of two adjacent sections (1, 2) and two side inserts (31, 41) which protrude from the central part (30, 40) so as to be connected to said sections (1, 2); characterized in that the central part (30, 40) and the side inserts (31, 41) of the corner part (3, 4) are made of one piece. 2. Inspection door according to claim 1, characterized in that the fixed frame (TF) contains four sections (2) and four corner parts (4); each corner part (4) of the fixed frame (TF) connecting two adjacent sections (2); while each corner part (3, 4) has side inserts (31, 41) in a perpendicular position. 3. Inspection door according to any of the preceding claims, characterized in that the corner part (3, 4) is made of plastic material or of die-cast aluminum or of composite material. 4. Inspection door according to any of the preceding claims, characterized in that the side inserts (31, 41) of the corner part (3, 4) have the shape of a rectangular plate. 5. Inspection door according to any one of the preceding claims, characterized in that each side insert (31, 41) has recessed seats (32, 42), while part of the section (1, 2) is connected by deformation. 6. An inspection door according to any one of the preceding claims, characterized in that each section (1, 2) has a C-shaped cross-section that defines a longitudinal channel (10, 20) open at the ends (11, 21) of the section; said insert (31, 41) of the corner part (3, 4) is inserted from the ends of the section into the longitudinal channel (10, 20) of the section (1, 2). 7. Inspection door according to claim 6, characterized in that the longitudinal channel (10, 20) of the section is defined by two opposite protrusions (18, 28); wherein each longitudinal projection (18, 28) is deformed in such a way as to define a projection (d) which protrudes inside the longitudinal channel (10, 20) to be connected to the recessed seat (32, 42) of the side insert (31, 41) ) of the corner part (3.4). 8. Inspection door according to any one of the preceding claims, characterized in that the central part (30, 40) of the corner part (3, 4) has a quadrangular shape and contains two outer sides (302, 402) and two inner sides (301, 401) equipped with said inserts (31, 41) in a projecting position; said middle part (30, 40) is outside the section (1, 2) in such a way that they form a corner of the frame (TM, TF). 9. Inspection door according to claim 8, characterized in that the outer sides (402) of the central part (40) of the corner part (4) of the fixed frame (TF) are connected by a curved section (40t) in such a way that the inspection door is free from sharp edges corners. 10. An inspection door according to any one of the preceding claims, characterized in that it contains securing means (81, 83) suitably configured to secure the movable frame (TM) relative to the fixed frame (TF) in the closed position. 11. Inspection door according to claim 10, characterized in that said securing means (81, 83) are located on the corner parts (3, 4) located in accordance with two adjacent corners (Q1, Q2) of the inspection door . 12. An inspection door according to any one of the preceding claims, characterized in that the connecting means (5, 6) are located on the corner parts (3, 4) located in accordance with two adjacent corners (Q3, A4) of the inspection the door. 13. An inspection door according to any one of claims 10 to 12, characterized in that the securing means (81, 83) include: a securing means (81) integral with the corner part (3) of the movable frame (TM); said securing means (81) is configured to define a recess (82) in the cutout; latch locking device (83) integral with corner piece (4) of fixed frame (TF); said latch securing device (83) comprises a fixed part (831) and a movable part (832) which is suspended from the fixed part (831) and has a stop (830) suitable for placement inside the recess (82) in the cutout. 14. Inspection door according to claim 13, characterized in that the securing means (81) is formed as one piece with the corner part (3) of the movable frame (TM); said latch SK 148-2023 U1 safety device (3) is mounted on a support (85) formed in one piece with a corner part (4) of a fixed frame (TF). 15. Inspection door according to any one of the preceding claims, characterized in that it contains end stop means (71, 72, 73) located between the corner part (3) of the movable frame (TM) and the corner part (4) of the fixed frame (TF) and suitable for stopping the movement of the moving frame (TM) when the moving frame (TM) is moved from the closed position to the open position. 16. Inspection door according to claim 15, characterized in that the end stop means (71, 72, 73) include: a first eyelet (71) connected to the corner part (4) of the fixed frame (TF); the second eyelet (72) connected to the corner part (3) of the movable frame (TM); and a chain (70) connected to the first link (72) on one side and to the second link (72) on the other side. 17. Inspection door according to claim 16, characterized in that the first eyelet (71) is made of one piece with the corner part (4) of the fixed frame (TF) and said second eyelet (72) is made of one piece with the corner part ( 3) moving frame (TM). 18. An inspection door according to any one of the preceding claims, characterized in that the connecting means (5, 6) include: a first element (6) having a first part (61) made in one piece with a corner part (4) of a fixed frame (TF ) and a second part (62) that extends beyond the corner part (3) of the movable frame (TM) and extends into the corner part (3) of the movable frame (TM); a second element (5) having a first part (51) made in one piece with the corner part (3) of the movable frame (TM) and a second part (52) which extends beyond the corner part (4) of the fixed frame (TF) and engages the corner part (4) fixed frame (TF). 19. An inspection door according to any one of claims 6 to 18, characterized in that each section (1, 2) preferably comprises two wings in an orthogonal position, namely: a first wing (14, 24) with a C-section having said longitudinal channel (10, 20); and a second wing (15, 25) which projects from one side of said first wing (14, 24) in the opposite direction with respect to said longitudinal channel (10, 20). 20. Inspection door according to claim 19, characterized in that the central part (30) of the corner part (3) of the movable frame (TM) contains two retaining edges (35) located on the two outer sides (302) of the central part (30); where the second wing (15) of the section (1) of the movable frame (TM) is placed side by side and rests on the retaining edge (35) of the central part (30) of the corner part (3) of the movable frame (TM) so that all the retaining edges (35 ) and the second wings (15) of the section (1) of the movable frame (TM) define a single outer annular edge of the movable frame (TM). 21. Inspection door according to claim 20, characterized in that the height of the second wing (15) of the section (1) of the movable frame (TM) is the same as the height of the retaining edge (35), so that the upper edges of the second wing (15) and the adjacent retaining the edges (35) are in one plane. 22. An inspection door according to claim 1 or according to any one of claims 3 to 10, characterized in that the movable frame (TM) and the panel are made of one piece, thus defining a single cover door (E).