WO2019123369A1

WO2019123369A1 - Apparatus and method for the assembly of a tensioned membrane panel

Info

Publication number: WO2019123369A1
Application number: PCT/IB2018/060428
Authority: WO
Inventors: Enzo Renato BERTOLI
Original assignee: Stamber S.R.L.
Priority date: 2017-12-20
Filing date: 2018-12-20
Publication date: 2019-06-27

Abstract

An apparatus for assembling a tensioned membrane panel, comprising a first support suitable for supporting a first half-frame of the panel, a second support suitable for supporting a second half-frame of the panel to be coupled to the first half-frame, support movement means, and at least two tensioning members in the form of bars suitable for retaining respective opposite edges of the panel membrane. Each tensioning member comprises a first member portion and a second member portion, which can be mutually coupled to hold the respective edge of the membrane. A longitudinal tensioning bead protrudes from a first surface of the first member portion facing the second member portion protrudes, when the two member portions are separated, the longitudinal tensioning bead being made of a yielding material so as to be at least partially flattened when the two member portions are coupled together, the edge of the membrane being held between the longitudinal tensioning bead and the second member portion.

Description

DESCRIPTION

"APPARATUS AND ME THOD FOR THE ASSEMBLY OF A TENSIONED

MEMBRANE PANEL"

[0001] The present invention relates to an apparatus for assembling a tensioned membrane panel, for example a filtering panel, i.e. a panel comprising a perimeter frame and a membrane, for example a flat filtering element, such as a fabric, retained and placed in tension by the perimeter frame.

[0002] In some known embodiments for the assembly of panels with a filtering element, the apparatus comprises a base on which a perimeter frame of the panel is positioned and, around the base and on each side of the filtering element, tensioning grippers suitable to retain the edges of the filtering element. These grippers are mounted on respective carriages in such a way as to move away from each other for tensioning the filtering element. When the filtering element is tensioned on the frame, the filtering element and the frame are fixed to each other by means of an adhesive.

[0003] The tensioning grippers in practice consist of clamps having two opposite flat surfaces between which a respective edge of the filtering element is inserted and which are then tightened together, for example in a mechanical or pneumatic manner. [0004] In order to retain and tension the filtering element, preventing it from slipping or tearing, the opposing surfaces of each clamp must have a certain width in the direction of translation of the carriages. The dimensions of the grippers and the need for a reciprocal displacement thereof determine the dimensions of the assembly apparatus.

[0005] Moreover, since at the end of the assembly operation of the perimeter frame of the panel, all the excess filtering element, or radially protruding from the perimeter frame, is cut and discarded, the wider the retaining surfaces of the filtering element of the grippers, the greater the waste.

[0006] The need to reduce the waste of material caused by the tensioning system adopted is therefore strongly felt.

[0007] The object of the present invention is to propose an assembly apparatus for a tensioned membrane panel which allows meeting such a requirement for limiting the material waste of the panel membrane.

[0008] Another object of the invention is to provide a more compact and lightweight assembly apparatus.

[0009] A further object of the invention is to make the operation of assembling a panel more automated and more reliable .

[0010] Said objects are achieved with an assembly apparatus for a tensioned membrane panel according to claim 1 and with an assembly method according to claim 11. The dependent claims describe preferred embodiments of the invention .

[0011] The features and the advantages of the assembly apparatus and method according to the invention shall be made readily apparent from the following description of preferred embodiments thereof, provided purely by way of a non-limiting example, with reference to the accompanying figures, in which:

[0012] Figure 1 is a perspective view of the assembly apparatus according to the invention;

[0013] figure 2 is a perspective view of the assembly apparatus, on which a half-frame of the frame of the panel to be assembled has been positioned;

[0014] figure 3 is a perspective view of the assembly apparatus in the configuration in figure 2, to which the other half-frame of the frame of the panel to be assembled has also been connected;

[0015] figure 4 is a perspective view of the assembly apparatus in the configuration in figure 3, on the tensioning bars whereof the membrane of the panel to be assembled is also positioned;

[0016] figure 5 is a perspective view of the assembly apparatus, in a configuration for coupling the two half-frames of the panel to be assembled and tensioning of the filtering element;

[0017] - figure 6 is an enlarged perspective view of a part of the assembly apparatus in the configuration in figure 5;

[0018] figure 7 is a perspective cross-sectional view of the assembly apparatus in the configuration in figure 5;

[0019] - figure 8 is a cross-section of a tensioning bar in an embodiment variant;

[0020] - figure 9 is a perspective view of a tensioned membrane panel assembled by the assembly apparatus according to the invention;

[0021] - figure 10 is a perspective exploded view of the panel in figure 9;

[0022] figure 11 is a perspective cross-sectional view of the panel in figure 9; and

[0023] figure 12 is a perspective cross-sectional view of the tensioned membrane panel in an embodiment variant.

[0024] In said drawings, reference numeral 1 indicates as a whole an apparatus for assembling a tensioned membrane panel 100 according to the invention.

[0025] The panel 100 to be assembled comprises a perimeter frame 102 and a membrane 104 retained and tensioned by the perimeter frame 102. The perimeter frame 102 consists of a first half-frame 106 and a second half-frame 108 which can be coupled to retain a peripheral portion of the membrane 104 therebetween.

[0026] The panel assembly apparatus comprises a first support 10 suitable to support the first half-frame 106 and a second support 12 suitable to support the second half-frame 108.

[0027] In the embodiment illustrated in the drawings, the apparatus is suitable for being placed on a horizontal plane, for example through the first support 10, which acts both as a support base for the apparatus and, with a surface 10' thereof facing upwards, as a support seat of the first half-frame 106.

[0028] The apparatus 1 further comprises support movement means 14 suitable for moving at least one between the first support 10 and the second support 12 along a support translation axis X, for example a vertical axis. In the example shown, the support movement means 14 are connected to the second support 12 for moving the second half-frame 108 with respect to the first half-frame 106.

[0029] The support movement means 14 can be moved between an inactive retracted position, in which the two half frames 106, 108 are separated (figure 3), and an advanced coupling position, in which the two half-frames 106, 108 are mutually coupled (figure 5) . In the example shown, the support translation axis X is a vertical axis, and the second support 108 is therefore movable between an inactive position, raised and spaced with respect to the first support 10, and a lowered active position, suitable for contacting the second half-frame 108 with the first half-frame 106.

[0030] The assembly apparatus 1 further comprises at least two tensioning members 16 in the form of tensioning bars. Each tensioning member 16 is suitable to retain a respective edge 104' of the membrane 104 of the panel 100.

[0031] Preferably, according to the shape of the panel to be assembled, two or more opposed pairs of tensioning members 16 are provided, each pair being positioned in such a way as to retain opposite edges 104' of the membrane 104 of the panel 100.

[0032] However, it should be noted that, as in the example shown, two opposite tensioning members 16 need not necessarily be parallel to one another. Preferably, in fact, such tensioning members 16 are positioned in such a way as to be parallel to the edges 104' of the membrane 104, which does not necessarily have a rectangular shape, but, as in the example, can have inclined sides.

[0033] For example, in the case of membrane 104 having a perimeter formed by four sides, the assembly apparatus is provided with two pairs of opposite tensioning members 16.

[0034] Each tensioning member 16 comprises a first member portion 18 and a second member portion 20. Such member portions 18, 20 can be mutually coupled to retain the respective edge 104' of the membrane 104.

[0035] For example, the two portions 18, 20 of the tensioning member consist of respective bars which are separate from each other and can be coupled to retain "sandwich-like", or as a vice, the respective edge 104' of the membrane 104.

[0036] In an embodiment variant, the two member portions 18, 20 are connected to each other and at least one is movable, for example in translation or rotation, between an open tensioning member position, which allows insertion of the membrane edge between the two portions, and a closed tensioning member position, for retaining the membrane .

[0037] From a first surface 18' of the first member portion

18, facing towards the second member portion 20, protrudes a longitudinal tensioning bead 19 made of a yielding material so as to be at least partially crushed when the two member portions are coupled together.

[0038] By longitudinal bead it is meant that it extends in the direction of the length of the tensioning member 16, which, as said above, is in the form of a bar, or of a member which has a prevailing extension in a direction orthogonal to the cross-section thereof.

[0039] The edge 104' of the membrane 104 is held at least predominantly between the longitudinal tensioning rod 19 and the second member portion 20.

[0040] In one embodiment, the longitudinal tensioning bead

19, when it is not crushed by the second member portion

20, has a convex, or flat, contact surface delimited by rounded corners, on which the membrane rests.

[0041] In one embodiment, when the two member portions 18, 20 are coupled together, the longitudinal tensioning rod 19 is crushed in such a way as to allow at least partial abutment between the facing surfaces of the two member portions .

[0042] In an embodiment illustrated in the drawings, the longitudinal tensioning bead 19 consists of a projecting portion of a longitudinal bar 24 housed in a longitudinal seat 22 formed in the first member portion 18.

[0043] For example, the longitudinal bar 24 has a circular cross-section. In this way it is possible to use, as a longitudinal bar, a rod already present on the market, for example a Teflon® rod.

[0044] The longitudinal tensioning bead 19 may, however, also be made in other ways, for example by depositing a strip of rubber paint or of an expanded polyurethane material on the first surface 18'.

[0045] In an embodiment shown in figures 1-7, the two member portions 18, 20 have respective first and second flat facing surfaces 18', 20'.

[0046] In the case of use of a tensioning bar 24, the bar seat 22 is a groove formed in the first flat surface 18' of the first tensioning member portion 18. The tensioning bar 24 protrudes from said first flat surface 18', so as to be engaged by the second flat surface 20' belonging to the second member portion 20.

[0047] In an embodiment variant shown in figure 8, the bar seat 22 has a substantially semi-circular section and the tensioning bar 24 extends about half the cross-section thereof from such a seat. In the second member portion 20 a second groove 26 is obtained, the concavity whereof is substantially complementary to a portion of the tensioning bar 24 which projects from the first member portion 18. The second groove 26 is therefore suitable for engaging in compression a substantially cylindrical surface portion of the tensioning bar 24. In other words, compared to the embodiment in figures 1-7, in which the second surface 20' is tangent to the tensioning bar 24, in the embodiment variant in figure 8, the contact surface between the second member portion 20 and the tensioning bar 24 is wider.

[0048] This embodiment has proved particularly effective by winding a peripheral portion of the membrane 24 around the tensioning bar 24, prior to insertion of the latter into the respective bar seat 22.

[0049] This embodiment, if on the one hand requires the making of a longitudinal groove also in the second member portion 20, and, during assembly of the panel, the winding of the membrane around the tensioning bar 24, on the other allows further reducing the width of the tensioning members 16.

[0050] In one embodiment, the two member portions 18, 20 are connected to each other by means of fixing screws 28. For example, a row of holes 30 for fixing screws 28 is formed in the member portions 18, 20 radially externally with respect to the longitudinal tensioning rod 19, i.e. along the side of the bead opposite the one facing the centre of the membrane 104. In fact, in such an area of the member portions the membrane 104 is not present, being able to terminate at the longitudinal tensioning bead 19, or even if the edge of the membrane 104' extends radially beyond the bead 19, when the two member portions are coupled, the radially outer membrane portion with respect to the bead 19 is substantially devoid of tension, or subjected to a substantially lower tension with respect to the radially inner portion with respect to the bead 19, since the crushing to which it is subjected by the two member portions 18, 20 is much lower than the crushing that occurs at the bead 19. Therefore, the presence of any holes 30 in the membrane and of the fixing screws 28 of the member portions 18, 20 which pass through it does not cause tears in the membrane 104.

[0051] In an embodiment variant, the two member portions 18, 20 are coupled to each other by means of pneumatic or hydraulic actuation means.

[0052] The use of tensioning members 16 such as those described above allows reducing the overall dimensions of the apparatus and, above all, the amount of waste of the membrane. In fact, the tightening of the membrane 104 by the tensioning members 16 takes place between the longitudinal tensioning bead 19 and the second surface 20' of the second member portion 20. The width of the tensioning members 16 is therefore determined only by the need to obtain the space for the bead 19 and the space for the coupling means, for example the fixing screws 28, of the two member portions. Such a width is therefore much smaller than the clamp tensioning members according to the prior art.

[0053] The tensioning members 16 define a membrane retaining plane where the membrane 104 substantially lies

(i.e., unless there is a possible concavity of the membrane) when the membrane 104 is retained by such tensioning members and before the movement of the support movement means .

[0054] In an embodiment shown in figures 1-7, such a membrane retaining plane is defined by the first surfaces 18' of the first member portions 18.

[0055] In the embodiment variant in figure 8, the membrane retaining plane substantially corresponds to the horizontal diametrical plane of the tensioning bar 24.

[0056] The tensioning members 16 are positioned in such a way that such a membrane retaining plane is parallel but spaced with respect to the membrane plane on which the membrane 104 lies when the support movement means 14 with the respective half-frame 108 are in advanced coupling position. The distance between these two planes determines the tension of the membrane 104.

[0057] In the illustrated example, taking as reference the horizontal resting surface of the apparatus, the first member portions 18 are positioned at a height, or they themselves have a height dimension, such that the membrane retaining plane is located at a height greater than the membrane plane, i.e. it is closer to the second support 12. In this way, when the second support 12, and the second half-frame 108 therewith, approaches the first half-frame 106, the membrane held by the tensioning members 16 is engaged by the second half-frame 108 and pressed downwards, and then tensioned, until it is locked between the two coupled half-frames 106, 108.

[0058] It should be noted that this embodiment which exploits the difference in height between the membrane plane and the membrane retaining plane allows avoiding the use of carriages for translating the tensioning members, and therefore limiting the dimensions of the apparatus .

[0059] In one embodiment, the tensioning of the membrane can be adjusted by modulating this height difference, for example by means of vertical movement means of the first support 10 and/or of the tensioning members 16.

[0060] In an embodiment variant, the tensioning of the membrane is obtained by means of tensioning members translation means, suitable to cause a translation of at least one tensioning member in a radial direction with respect to the support translation axis.

[0061] In one embodiment, the tensioning members 16 are positioned on the first support 10, preferably around the support area of the first half-frame 106.

[0062] In one embodiment, the apparatus comprises a bridge framework 31 which extends above the first support 10 and which comprises a crosspiece 32 carrying the support movement means 14.

[0063] The second support 12 is fixed to the support movement means 14.

[0064] For example, the support movement means 14 comprise one or more pneumatic or hydraulic cylinders 142.

[0065] In one embodiment, the second support 12 is a plate^¬ like support having a perimeter substantially corresponding to the perimeter of the perimeter frame 102 of the panel 100.

[0066] The second half-frame 108 is releasably fixed to a peripheral portion of such a plate-like support 12.

[0067] It is also an object of the present invention to provide a method of assembling a tensioned membrane panel which employs the assembly apparatus 1 described above.

[0068] Initially, the assembly apparatus is in a configuration suitable for receiving the parts of the panel, shown in figure 1. The open tensioning members 16 are seen, so as to allow the edges 104' of the membrane 104 to be positioned on the first member portions 18. The support movement means 14 are in retracted inactive position .

[0069] In a second step, shown in figures 2 and 3, the first half-frame 106 is positioned on the first support

10, while the second half-frame 108 is connected, for example by means of adhesive or mechanical systems, to the second support 12.

[0070] It should be noted, in particular, that thanks to the technical solution described above, the tensioning members 16 are in contact or almost in contact with the outer sides of the first half-frame 106, allowing a considerable reduction of the membrane waste.

[0071] Subsequently, the membrane 104 is positioned on the first member portions 18 of the tensioning members 16 ( figure 4 ) .

[0072] The membrane 104 can simply be placed on the first member portions 18, taking care that the edges of the membrane rest on the longitudinal tensioning bead 19.

[0073] In an embodiment variant, shown in figure 8, the edges of the membrane are previously wrapped around the respective tensioning bars 24 and these are then positioned in the respective longitudinal seats 22.

[0074] Once the tensioning members 16 have been tightened in a membrane retaining configuration, the support movement means 14 are driven to translate so as to place the two half-frames in mutual contact, with the interposition of the membrane 104 (figure 5) .

[0075] The enlarged views in figures 6 and 7 highlight the difference in height between the plane on which the membrane lies when the two half-frames 106, 108 are coupled and the membrane retaining plane defined by the tensioning members 16.

[0076] At this point, the two half-frames 106, 108 of the panel are mutually clamped so as to complete the formation of the perimeter frame 102.

[0077] The two half-frames can be locked in various manners, for example by means of gluing means or, as will be described below, by mechanical means.

[0078] Once the frame 102 of the panel 100 is assembled, the tensioning members 16 can be released, that is, opened, and the second half-frame 108 can be separated from the second support 12, so as to allow the panel 100 to be extracted from the assembly apparatus 1.

[0079] While the assembled panel is still in the assembly apparatus, or after the removal thereof, the excess membrane portion can be cut, i.e. the portion radially protruding from the perimeter frame 102.

[0080] In an embodiment variant, after locking the membrane in the tensioning members, the tensioning of the membrane is obtained by translating at least one of each pair of opposing tensioning members away from the other.

[0081] As mentioned above, in one embodiment of the panel assembly method, the coupling between the two half-frames

106, 108 occurs mechanically. To this end, a technical device similar to that used to retain the membrane between the member portions 18, 20 of the tensioning members, in the embodiment described with reference to figures 1-7, is used to make the panel.

[0082] It should be noted that the assembly method described above does not require heating means of adhesives or other materials suitable for being melted to obtain the coupling between the two half-frames. Consequently, the two supports can be pressed together, with the membrane interposed, for as long as necessary to tension the membrane and lock it in place. In other words, during assembly, the membrane is subjected only to a controlled mechanical compression action and does not risk to be damaged, for example, due to the exposure to heat sources.

[0083] It is also an object of the present invention to provide a method for producing and assembling a tensioned membrane panel, which provides for making a panel as described below and assembling such a panel using the assembly method and apparatus according to the present invention .

[0084] In the first surface 106 of the first half-frame 14 suitable to come into contact with a corresponding second surface 108 of the second half-frame 108 there is formed a frame bar seat 110 in which a frame bar 112 of substantially circular section is housed. Furthermore, the frame bar seat 110 is open towards the second half frame 108.

[0085] The frame bar 112 projects from the frame bar seat 110 towards the second half-frame 108 when the two half- frames are separated, so as to be engageable by the second surface 108' of the second half-frame 108, facing the first half-frame 106, when the second half-frame 108 is coupled to the first half-frame 108.

[0086] This frame bar 112 is made of a yielding material, that is to say deformable, so as to be at least partly flattened when the two half-frames 106, 108 are coupled together .

[0087] When the panel is assembled, a peripheral portion of the membrane is then retained between the frame bar 112 and the second half-frame 108.

[0088] It should be noted that, as illustrated in figures 11 and 12, when the second half-frame 108 is coupled to the first half-frame 106, the frame rod 112 is compressed such that the first surface 106' and the second surface 108', facing each other, are substantially in mutual contact .

[0089] The presence of the deformable frame bar 112 allows reducing the crushing of the membrane 104 between the two half-frames with respect to a perimeter frame not provided with such a bar. In particular, the filtering element, especially if made of fabric, placed in compression by the two half-frames in the absence of a yielding bar would undergo a deformation of the interlacing of the fabric threads by crushing, which could lead to the formation of break points. With the yielding bar, on the other hand, the crushing of the fabric does not take place or occurs in a reduced manner as it is the bead itself that undergoes deformation.

[0090] It should be noted that the pressure exerted by the two half-frames 106, 108 must be higher the lower the coefficient of friction between the facing surfaces of the two half-frames and the membrane. For example, facing flat metal surfaces of the two half-frames have a low coefficient of friction, which would therefore require high pressure on the peripheral portion of the membrane.

[0091] In the panel according to the embodiment described and illustrated in the drawings, instead, the membrane 104 is held substantially between the second surface 108' of the second half-frame 108 facing the first half-frame 106 and the surface of the emerging portion of the frame bar 112. Since the bar is made of deformable material, and due to the reduced contact surface between the second half-frame and the frame bar, the friction between the frame bar 112 and the membrane 104 is greater than in the embodiment without frame bar and the closing force of the two half-frames can be reduced.

[0092] Furthermore, the yieldable or deformable frame bar 112 compensates for any lack of coplanarity of the two contact surfaces 106', 108' of the half-frames, which, in the absence of a bar, would increase the risk of tearing the membrane when tensioned between such surfaces.

[0093] The use of the frame bar 112 avoids the use of means for gluing the peripheral portion of the membrane 104 to the two half-frames 106, 108.

[0094] Therefore, simply by decoupling the two half-frames from each other, the membrane can be removed and the perimeter frame and be immediately reused.

[0095] For example, the two half-frames are fixed to each other by means of screws or rivets 114.

[0096] In one embodiment, the frame bar 112 consists of a rod of a plastic material, for example Teflon®.

[0097] In one embodiment, the perimeter frame 102 is continuous along the entire perimeter of the panel.

[0098] Preferably, also the frame bar seat 110 and the frame bar 112 are continuous along the entire perimeter of the panel. For example, a Teflon® rod is easily foldable to follow the perimeter of the membrane, and therefore of the perimeter frame.

[0099] In one embodiment, each half-frame 106, 108 is constructed in one piece, for example by mechanical machining or by moulding.

[00100] In one embodiment, one or both half-frames comprise at least three half-frame segments connected to the respective ends. In this way, each segment can advantageously be obtained from a bar.

[00101] However, even in the case of segments obtained from a bar, it is preferable to give continuity to the perimeter frame and to the frame bar, for example by using angular joints which connect adjacent half -frame segments to each other.

[00102] In one embodiment, the first and second surfaces 106', 108' facing the two half-frames are flat surfaces, with the exception of the bar seat, thus making the two half-frames easily obtainable.

[00103] In the example shown in figures 9-11, the contact plane between the two flat facing surfaces 106', 108' of the two half-frames coincides with the plane in which the membrane 104 lies. The latter thus extends from an intermediate height of the height of the perimeter frame 102.

[00104] In the embodiment variant shown in figure 12, instead, an inner peripheral portion 116 of one (106) of the two half-frames extends in height substantially equal to the thickness of the other half-frame 108, such that the membrane 104 is flush with the perimeter frame. Such an embodiment of panel is intended, for example, for the screen printing sector.

[00105] In one embodiment, the holes 114' for the screws or rivets 114 for coupling the two half-frames are formed in a position of the half-frames and the peripheral radially outer membrane portion with respect to the frame bar 112. In fact, when the membrane 104 is tensioned between the two half-frames, the radially outer membrane portion with respect to the frame bar 112 is substantially tension-free, or subjected to a substantially lower tension than the radially inner portion with respect to the bar, since the crushing to which it is subjected by the two half-frames is, as explained above, much lower than the crushing that occurs at the frame bar 112. Therefore, such an outer portion of the membrane can relax when the membrane tensioning action ceases during assembly of the panel. Accordingly, it is possible to make the holes 114' in the membrane 104 when the two half-frames are coupled and then apply the screws or rivets 114 without causing tears in the membrane itself.

[00106] It should be noted that the frame with bar 112, due to the fact that the membrane is clamped between the frame rod 112 and the upper half-frame 108, allows positioning the tensioning members very close to, virtually in contact with, the half-frame and at the same time with the membrane retaining plane at a different height than the membrane plane of the panel frame. In fact, this difference in height causes an inclination of the membrane 104 between the perimeter frame 102 and the tensioning members 16 which prevents optimum adhesion of the entire membrane on the first half-frame 108 and which would therefore hinder a reliable bonding of the membrane to the two half-frames, especially when using glue as a fixing means.

[00107] On the other hand, the inclination of the membrane and therefore the non-perfect adherence to the entire surface of the lower half-frame does not affect the reliability of the fixing in the case of a perimeter frame with frame bar 112. In fact, the membrane is clamped on the frame bar 112, preferably positioned near the radially inner edge of the first half-frame 106, and the remaining membrane portion radially external to the frame bar does not affect the locking of the membrane between the two half-frames and can therefore also not be perfectly adherent to the surface of the first half frame .

[00108] Similarly to what has been described for the tensioning members, also in the case of the perimeter frame, in place of the frame bar, any other frame bead projecting from a half-frame can be used and made of yielding material. For example, such a bead may be made by depositing on the first half-frame 106 a strip of rubbery paint or expanded polyurethane material .

[00109] The assembly method described above, when using the panel with a frame bead, is therefore particularly advantageous as it allows reducing the overall dimensions of the apparatus, simplifying its structure, avoiding the use of glue, and therefore reducing assembly time.

[oollo] A man skilled in the art may make several changes, adjustments, adaptations and replacements of elements with other functionally equivalent ones to the embodiments of the apparatus and method for assembling a tensioned membrane panel according to the invention in order to meet incidental needs, without departing from the scope of the following claims. Each of the features described as belonging to a possible embodiment can be obtained independently of the other embodiments described .

Claims

1. Apparatus for the assembly of a tensioned membrane panel, wherein said tensioned membrane panel comprises a perimeter frame and a membrane which is retained and placed in tension by the perimeter frame, and where the perimeter frame is formed of a first half-frame and a second half-frame which are suitable for being coupled to retain therebetween a peripheral portion of the membrane, the apparatus comprising:

a first support suitable to support the first half-frame;

- a second support suitable to support the second half-frame;

- support moving means suitable to move at least one of said first and second supports along a support translation axis between an inactive retracted position, wherein the two half-frames are separated, and an advanced coupling position, wherein the two half-frames are coupled to each other;

- at least two tensioning members in the form of bars suitable to hold the respective opposite edges of the panel membrane;

wherein each tensioning member comprises a first member portion and a second member portion, which may be mutually coupled to hold the respective edge of the membrane, and wherein a longitudinal tensioning bead protrudes from a first surface of the first member portion facing the second member portion protrudes, when the two member portions are separated, the longitudinal tensioning bead being made of a yielding material so as to be at least partially flattened when the two member portions are coupled together, the edge of the membrane being held between the longitudinal tensioning bead and the second member portion.

2. Apparatus according to the preceding claim, wherein the two member portions have respective flat facing surfaces, the longitudinal tensioning bead protruding from the flat surface of the first member portion.

3. Apparatus according to claim 1 or 2, wherein the longitudinal tensioning bead has a contact surface on which the membrane rests, said contact surface being convex or flat and delimited by rounded corners.

4. Apparatus according to any one of the preceding claims, wherein the longitudinal tensioning bead is formed by a projecting portion of a tensioning bar housed in a bar seat formed in the first frame portion and protruding from the first surface.

5. Apparatus according to the preceding claim, wherein the tensioning bar consists of a rod made of a plastic material, for example Teflon®.

6. Apparatus according to any one of the preceding claims, wherein the two member portions are connected to each other by means of screws.

7. Apparatus according to the preceding claim, wherein the holes for the screws are formed in the member portions radially outwardly with respect to the longitudinal tensioning bead.

8. Apparatus according to any one of claims 1-5, wherein the two member portions are coupled together by means of pneumatic or hydraulic actuation means.

9. Apparatus according to any one of the preceding claims, wherein the tensioning members define a membrane retaining plane wherein the membrane lies when the support movement means are in a retracted inactive position, the tensioning members having a height such that they are positioned in a manner such that said membrane retaining plane is parallel but spaced with respect to the membrane plane on which the membrane lies when the support movement means with the respective half frame are in the advanced coupling position, the distance between said planes determining the tensioning of the membrane .

10. Apparatus according to any one of the preceding claims, comprising tensioning members translation means, suitable to cause a translation of at least one tensioning member in a radial direction with respect to the support translation axis.

11. Apparatus according to any one of the preceding claims, comprising a bridge framework which extends above the first support and which comprises a crosspiece carrying the support movement means, the second support being fixed to said support movement means.

12. Apparatus according to any one of the preceding claims, wherein the second support is a plate-like support having a perimeter substantially corresponding to the perimeter of the perimeter frame of the panel, the second half-frame being releasably fixed to a peripheral portion of said plate-like support.

13. Method of construction of a tensioned membrane panel, e.g. a filtering fabric panel, wherein said tensioned membrane panel comprises a perimeter frame and a membrane which is retained and placed in tension by the perimeter frame, and where the perimeter frame is composed of a first half-frame and a second half-frame which may be coupled to retain therebetween a peripheral portion of the membrane, the apparatus comprising the steps of:

- providing an apparatus according to any one of the previous claims;

positioning the first half-frame on the first support ;

connecting the second half-frame to the second support ;

- positioning the membrane on the first portions of the tensioning members;

- tightening the tensioning members so as to lock the membrane;

actuating the support movement means so as to couple the two half-frames together;

- fixing the two half-frames together;

- opening the tensioning members in order to release the membrane;

- disconnecting the panel from the supports;

- cutting off the excess membrane.

14. Method according to the previous claim, wherein the tensioning of the membrane is obtained from the difference in height between the membrane plane wherein the membrane lies when the two half-frames are coupled and the membrane retaining plane defined by the surfaces of the first portions of the tensioning members on which the edges of the membrane are positioned.

15. Method according to claim 12 or 13, wherein, after locking the membrane in the tensioning members, the tensioning of the membrane is obtained by translating at least one of each pair of opposing tensioning members away from the other.

16. Method of manufacturing and assembling a membrane panel, for example a filtering fabric panel, where said membrane panel comprises a perimeter frame and a membrane held and placed in tension by the perimeter frame, comprising the steps of:

- making a first half-frame and a second half-frame which may be coupled to retain a peripheral portion of the tensioned membrane, wherein a first surface of the first half-frame turned toward the second half-frame protrudes when the two half-frames are separated, a frame bead made of a yielding material so as to be at least partially flattened when the two half-frames are coupled together, a peripheral portion of the membrane being held between the frame bead and the second half-frame;

- assembling the tensioned member panel by means of the assembly method according to any of claims 13 to 15.

17. Method of construction according to the preceding claim, wherein the two half-frames are fixed to each other by means of screws or rivets, the holes for the screws or rivets being formed in a position of the half frames and of the peripheral portion of the membrane radially external to the frame bead.

18. Method of construction according to the preceding claim, wherein the opening step of the tensioning members for releasing the membrane takes place before the mutual fixing of the two coupled half-frames, and wherein said step of fixing the two half-frames together comprises the sub-steps of:

- making holes in the membrane for passing the screws or rivets therethrough, said holes being made in a position of the peripheral portion of the membrane radially external with respect to the frame bead;

- applying the screws or rivets through the holes in the membrane .