WO2007102177A1

WO2007102177A1 - Large wize openable door for display cases

Info

Publication number: WO2007102177A1
Application number: PCT/IT2006/000139
Authority: WO
Inventors: Alessandro Goppion
Original assignee: Goppion S.P.A.
Priority date: 2006-03-09
Filing date: 2006-03-09
Publication date: 2007-09-13
Also published as: EP1991754A1

Abstract

Openable door (15) of display case (10) includes a panel (20) of transparent material carried by a frame (21), wherein the frame includes a side formed by a bar (23) connected to two adjacent sides by two corner joints (24). The bar (23) has a hollow cross section and the corner joints (24) are fastened one to the other by a tie rod (50) extended longitudinally inside bar (23), tightened between the two joints (24) so as to put bar (24) in a longitudinal precompression state. The precompression caused by the tie rod (50) is such that each part of bar (24) is prevalently compression stressed in all operation conditions of the door (15).

Description

Large size opβnable door for display cases

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The present invention relates to an openable door for a display case, and more specifically, to a large size and heavy weight door.

Display cases function, to protect and make publicly visible objects, such as works of art. Thus, it is necessary to both guarantee visibility to the public through suitable panels of ^' transparent material and to guarantee the necessary protection of the object on display, through the use of materials appropriate for the type of protection requested. In particular, there may be protection from theft or damage; such a case requires particularly robust materials which are consequently heavy. Above all, transparent materials such as glass may be very heavy when a high level of resistance is necessary.

The heavy weight may be a problem in many installations, above all for openable doors. In fact, the actions of opening and closing may bring the doors to a position in which their own weight generates high stress in the materials.

To avoid the risk not only of a structural collapse but also of deformations of the unit such as to jeopardize the correct operation of the opening mechanisms, normally the size of the doors is smaller than heavier are the materials necessary for requirements of protection. In other cases, to withstand the heavy weights, the doors are provided with massive frames, which however limit visibility of the objects on display. In yet other cases, the display case is designed so that optimal visibility is guaranteed by one or more large, fixed doors, limiting the opening to so-called secondary, smaller, doors; this solution nevertheless results in access difficulties for museum personnel in operations of insertion or removal of the objects displayed, if pbjects are large in size.

The problem at the basis of the present invention is to enable the construction of display cases with large and heavy openable doors, in a way so as not to obstruct the visibility of the objects displayed.

Accordingly, the present invention relates to an openable door according to claim 1. Preferred characteristic are indicated in dependent claims.

In particular,, an openable door for display case includes a panel of transparent material carried by a frame, wherein the frame includes a side formed by a bar connected at two adjacent sides to two respective corner joints, characterized in that the bar has a hollow cross section and the two corner" joints are fastened to each other by a tie rod extending longitudinally inside the bar, tightened between the two joints so as to put the bar in a longitudinal precornpressed state. The precompression caused by the tie rod acts such that each segment of the bar is compression stressed in the operating conditions of the ' door. The presence of compression stress only avoids the so-called critical range {the passage from compression to traction and vice-versa) , in which deformations are greater and thus create greater difficulty for the door. The precompressed bar is thus much more resistant and less deformable than an un-compressed bar, and may thus have a smaller size. At the same time, the tie rod must be able to bear practically only traction stresses, and may be easily chosen to such purpose.

Preferably, the amount of the preσompression is such that the bar remains compression stressed in any condition of use of the door. Depending on the weight of the door and the positions which it must assume, it will be possible to determine which is the minimum amount of precompression necessary so that in any condition of use the bar is anyway subject to stress substantially of compression only.

Preferably, the bar is made of a material having a relatively low mechanical tensile strength whereas the tie rod is made of a material having a relatively high mechanical tensile strength. In fact,, it is not necessary that the material of the rod has a high strength to tensile stresses, whereas it is not necessary that the material of the tie rod has a high strength to stresses other than tensile stress. For example, and preferably, the bar is of extruded aluminium and the tie rod is of steel.

The corner joints may have different shapes. Preferably, however, each corner joint is provided, at a coupling end to the bar, with a shank, shaped and sized such as to fit tightly in the bar, and with a shoulder, shaped and sized such as to contact engage against the bar.

In fact, due to the precompression of the bar by the tie rod, in the coupling of each joint and the bar potentially high thrusts are generated and the aforementioned conformation is such as to favour the best transfer of such thrusts between the two elements.

^■• preferably, each corner joint includes a through hole formed in the shank for the passage of the tie rod, and a connection seat adjacent to the hole to be engaged with a connection member of the tie rod; more preferably, the connection member includes a nut, screwed on a threaded end of the tie rod. Such characteristics guarantee a simple and effective anchoring of the tie rod to the joint.

As mentioned, the tie rod extends longitudinally in the bar; by this it is meant that the tie rod extends from one end of the bar to the other,, i.e. between the two joints adjacent to the bar. ^'Preferably, the tie rod extends axially inside the bar, meaning that it is parallel to the longitudinal direction of the bar and is located in a central position of it. Nevertheless, in particular situations, for example to compensate structural asymmetries of the door, a different position may be useful.

Typically a display case door has a rectangular shape and thus includes four bars along the four sides of the rectangle. Depending on applications, it will possible to identify -which of the four sides are potentially 30 highly stressed to suggest precompression of the corresponding bar in accordance with the invention; for example, in the case of a vertical door opening via tilting around a horizontal axis which passes substantially through the upper bar, the system of hinges could be such that such upper bar is not -greatly stressed even if the door is very heavy. Nevertheless, also for simplicity of manufacture and design, the frame preferably comprises all four bars and the four corner joints; clearly, in the anyway rare case of a non-rectangular door, the number of bars will be different.

Preferably, the transparent material of the panel is highly-resistant armored glass. Thanks to the invention, such very heavy material is usable also when the display case has large dimensions.

Further characteristics and advantages of a door according to the invention^' will better result from the following detailed description of a preferred embodiment, made with reference to the attached drawings. In these drawings :

-figure 1 is a perspective, schematic view of a display case with a door according to the invention; -figure 2 is a partially exploded perspective view of the door of fig. 1; -fig. 3 is a perspective view in an enlarged scale of a detail of the door of fig 2.

In the figures, 10 indicates wholly a display case, which includes a base 11 and an upright 12; on the base 11 and adjacent to the upright 12, a parallelepiped container body 13 is provided, extended on the upright 12 and closed by a rectangular openable door 15 according to the invention. Display case .10 is a display case typically engaged for displaying carpets or tapestries, and only the front side of it is thus intended for displaying objects inside_* The height and width of display case 10 (with reference to the position of use shown in the figures, in particular fig 1), and consequently . of door 15, may be very great, even many metres, whereas the depth of display case 10 is relatively modest.

In the base 11 and/or in the upright 12, service systems and devices for display case 10 may be housed, such as systems for illumination, climate control, alarm, protection, etc. Such systems are neither illustrated nor described hereafter, as they are per se conventional.

Door 15 includes a rectangular transparent panel 20, for example made of highly resistant armored glass, such as reinforced glass or bullet-proof glass. Panel 20 is carried by a rectangular frame 21, formed by four bars, indicated indistinctly with 23 and specifically with 23a, 23b, 23c, and 23d, and by four corner joints, indicated indistinctly with 24 and specifically with 24a, 24b, 24c, and 24d. Possibly, another transparent panel 26 can be provided, parallel and spaced from panel 20, still carried by frame 21.

Each bar 23 is formed by 'a ^' portion of an aluminum profile having a hollow cross section, with an internal hollow core 31 with square cross section, extended along the entire length of bar 23 between two opposite ends 32. On a face 34, each bar 23 is then provided with means for fastening panel 20, for example a channel 35, not illustrated in detail because it is per se conventional; panel 26 is instead applied externally to frame 21, with conventional means, not illustrated. The four bars 23 are substantially equal one to another, differing only in length; bars 23a and 23c are longer, whereas bars 23b and 23d are shorter.

Each corner joint is formed by a block of massive aluminum, obtained by fusion and/or mechanical working, provided with two shanks at two ends thereof (at right angles to each other) for coupling with the two bars 23 that converge at joint 24« The two shanks 41 have both a square shape, correspondent to the cross section of the hollow core 31 of bars 23_/ so as to fit tightly in these hollow cores. Around shanks 21, shoulders are provided for support, i.e. contact engagement with ends 32 of bars 23. The four corner joints 24 are different among themselves, even though they have the same shanks 41 and shoulders 42. In particular, corner joints 24a and 24b are mirror equal one to the other and have an elongated shape, and inside each a relatively ample space 43 is obtained. Also the two corner joints 24c and 24d are mirror equal one to the other, but have a compact form, and inside each a relatively small space 44 is obtained. In the center of each shank 41, a through hole 45 is provided, facing interior space 43 or 44.

Inside hollow cores 31 tie rods 50 are housed, formed of respective steel rods or of material having high tensile strength. The ends 51 of each tie rod 50 are inserted in respective holes 45 formed in shanks 41 and project into spaces 43 or 44 through such holes 45. Ends 51 of tie rod 50 are threaded, and nuts 52 are screwed to them, which rest on internal walls 46 of shanks 41, around holes 45. Each threaded end 51 and respective nut 52 together form a connection member between tie rod 50 and corner joint 24; each internal wall 46 around hole 45 forms a connection seat to be engaged with the aforementioned connection member. Each tie rod 50, which, as mentioned, is inserted in one of the bars 23 and fastened to the two corner joints 24 adjacent to bar 23, is placed in tension, suitably acting on nuts 52, so as to put bar 23 in a longitudinal precompression state. The amount of this precompression is chosen such that bar 23 remains compression stressed in each condition of use of door 15. Thanks to the hollow conformation of bar 23 and with a suitable choice of materials employed for both bar 23 and tie rod 50, it is possible to apply very high precompression,, which assures the preservation of aforementioned conditions even if door 15 is very large and heavy. In this way, when conditions of use place heavy loads on frame 21, for example because during opening door 15 is completely overhanging relative to container body 13, local stress in each part, of the material due to such loads is superimposed to the stress already present, determined by the pretension of tie rods 50. Where load-bearing stress is primarily tensile, shearing, or bending, in the material of bars 23 of frame 21 such stress will reduce the absolute value of pre-existing compressive .stress, alleviating the working conditions of the material. Instead, where the load bearing stress is due primarily to compression, in the material of bars 23 such stress will increase the absolute value of pre-existing compressive stress; however, the tensile strength of the material of bars 23 is such as not to be adversely affected by an increase of stress of this type .

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Claims

1. Openable door for display cases (10), comprising a panel (20) to transparent material carried by a frame (21) , wherein the frame includes a side formed by a bar (23) connected at two adjacent sides to two respective corner joints (24), characterized in that the bar (23) has a hollow cross section and the two corner joints (24) are fastened to each other , by a tie rod (50) extending longitudinally inside bar (23) _r tightened between the two joints (24) so as to put the bar (23) in a longitudinal preσompressed state,

2. Door according to claim l_r wherein the amount of the precompression is such that the bar (23) remains compression stressed in any condition of use of the door (15) .

3. Door according to claim 1 or 2, wherein the bar (23) is of a material having a relatively low mechanical tensile strength whereas the tie rod (50) is made of a material having a relatively high mechanical tensile strength.

4. Door according to claim 3, wherein bar (23) is of extruded aluminum and the tie rod (50) is of steel.

5. Door according to any of the preceding claims, wherein each corner joint (24) is provided, at a coupling end to the bar (23), with a shank (41), shaped and sized such as to fit tightly in the bar (23), and with a shoulder (42), shaped and sized such as to contact engage against the bar (43).

6. Door according to claim 5, wherein each corner joint (24) includes a through hole (45) formed in the shank (41) for the passage of the tie rod (50) _r and a connection seat (46) adjacent to the hole (45) for engagement to a connection member (51,52) of the tie rod (50).

7. Door according to' claim β, wherein the connection member includes a nut (52) screwed to a threaded end (51) of the tie rod (50) .

8. Door according to any of the preceding claims, wherein the tie rod (50) is axially extended inside the bar 23.

9. Door according to any of the preceding claims, wherein the frame (21) includes four bars (23) and four corner joints (24) ,

10. Door according to any of the preceding claims, where in the transparent material of the panel (20) is highly resistant armored glass.