US 3324930 A
Description (OCR text may contain errors)
June i 3, 19%? R. commrao 3,324,%U
FOLDING SLIDING DOORS Filed July 26, 1965 2 SheetsSheet 1 June 33, 19657 R. COLOMBO FOLDING SLIDING DOORS 2 Sheets-Sheet 2 Filed July 26, 1965 United States Patent 3,324,930 FOLDING SLIDING DOORS Roberto Colombo, Turin, Italy, assignor to Lavorazione Materie Plastiche (L.M.P.) S.p.A., Turin, Italy Filed July 26, 1965. Ser. No. 474,905
Claims priority, application Italy, Aug. 3, 1964,
4,566/ 64 2 Claims. (Cl. 160231) This invention relates to folding sliding doors of the character wherein the adjoining vertical edges of the slats are hinged to each other by means of a vertically extending flexible strip of plastics comprising a bead on each of its longitudinal edges inserted into a mortise in the corresponding slat.
Folding sliding doors of the above-defined character are disclosed by British patent specification 927,590, for example, and it will be evident to experts that the expedient of using hinges made of flexible strips of extruded plastics strongly contributes to both the secondary of manufacture and competivity of the door, also because of their noiseless operation.
However, doors of the character defined above suffer from a drawback residing in that the adjoining strips crack relatively easily and tear within a relatively short period of use, even when molecularly orientated polypropylene is used as material for the strips. Strips comprising a relatively thin web section between the beads flex better than thick-webbed ones; however, thin-webbed strips do not satisfactorily withstand the tensile and compressive forces which they are called upon to transmit from a slat to another on unfolding and folding-up the door, particularly in the case of a careless use of the latter (as frequently occurs in practice). Relatively thick-webbed, almost rigid strips flex hardly at all; thus, they crack very easily particularly because the dihedral angle formed by a pair of adjacent slats in a folding sliding door is variable within very wide limits (0 in folded-up condition and 170-180 in the unfolded condition of the door).
The general object of this invention is to improve folding sliding doors of the character defined hereinbefore thereby to avoid the drawbacks just pointed out above.
Thus, the invention provides a folding sliding door of the character wherein the adjoining vertical edges of the slats are hinged to each other by means of a vertically extending flexible strip of plastics comprising a bead on each of its longitudinal edges inserted into a mortise in the corresponding slat, characterized in that: (a) both the bead and mortise are of circular cross-sectional profile; (b) the bead is lose in the mortise; (c) the mortise opens on the edge of its slat through a slit larger than the web of the strip interconnecting the beads but smaller than the diameter of the latter, whereby each of the heads is rotatable in its associated mortise through a limited angle; (d) a vertically effective abutment is provided on the slot in the region of the lower end of the mortise preventing the strip from slipping-out downwardly from the slat.
Further features and advantages of the invention will become evident to experts from the following description, wherein reference is made to the accompanying drawings in which:
FIGURE 1 is a fragmentary plan-view of an embodiment of the invention;
FIGURE 2 is an enlarged cross-sectional view of one of the corners formed by the slats in FIG. 1;
FIGURE 3 shows the corner of FIG. 2 in folded-up condition of the door;
FIGURE 4 is a vertical cross-sectional view on line IV-IV of FIG. 2.
The door shown comprises a horizontal overhead track 10, consisting of a rigid channel member including a pair of in-turned opposed flanges 10A, 10B leaving free therebetween a slot 11 (FIG. 1). Each of the slats 12, 14, 16 shown is suspended from the track by means of a runner R, fitted to the upper end of the slat in alignment with the vertical central axis of the latter, according to the conventional practice, in an arrangement wherein the runner is slidably or rollably supported by the flanges 10A, 108 while permitting its associated slat to angularly swing about said axis (see arrows F) as the door is being folded-up or unfolded. The exact structure of the runners is not part of this invention; in the embodiment shown, the runners R essentially comprise a hemispherical head which is slidably and rotatably supported by the flanges 10A, 10B and is rigidly connected to its associated slat by means of a cylindrical neck passing through the slot 11.
FIGS. 1 and 2 show the door in a substantially halfopen condition, as will be readily recognized from the dihedral angle formed by the slats. The adjoining vertical edges of each pair 1244, 14-16 of consecutive slats are hinged to each other by means of a length of an extruded strip '18 of flexible plastics, advantageously polypropylene, extending vertically. The strip comprises a flat flexible web section 19 interconnecting a pair of beads 20', 21 of circular cross-sectional shape, the polypropylene material in said web section 19 being advantageously cold-drawn in the plane of the section perpendicularly to the beads thereby to molecularly orientate the material in the latter direction with the view to increase its hinge-forming properties, according to concepts known per se: The original shape of the strip is that shown in FIG. 2, in which the web section 19 is planar, i.e. extending directly from a head to the other.
Each of the slats consists of a length of a flat tubular profile of extruded rigid plastics, such as rigid PVC, for example. The adjoining edges of the slats are each extrusion-formed with a mortise 22, 23, respectively, of a circular cross-sectional shape, opening on its respective edge through a likewise extrusion-formed slit 24, 25, respectively. The beads 20, 21 are longitudinally slipped into their associated mortises 22, 23, respectively, the diameter of the beads being somewhat smaller than the diameter of the mortises so that the former are smoothly loose in the latter (as has been exaggeratedly shown in FIGS. 2, 3 and 4). Moreover, the width of the slits 24, 25 is greater than the thickness of the web section 19 of the strip 18, but is smaller than the diameter of the beads. In this manner, each of the beads is smoothly rotatable in its associated mortise through a limited angle as the door is being folded-up or unfolded.
It will be also seen in FIG. 2 that, in the condition shown, the slits 24, 25 are directly opposed to each other and, at the same time, the Web section 19 of the strip 18 is in its original planar configuration, so that no internal stress is present in the strip. Now, as the door is being displaced to its fully open condition (in which the dihedral angle is zero; FIG. 3), there is a moment in which the inner edge of each of the slits 24, 25, such as the edge denoted by 22A in FIG. 2, abuts the web section 19 of the strip and flexes said section to the outside by being co-adjuvated by the compressive forces acting transversely between the beads 20, 21 as the door is being folded-up. Thus, as opposed to prior art structures, the passage from the condition of FIG. 2 to the condition of FIG. 3 of the door is accompanied at first by a limited rotation of each of the beads in its mortise, without the web of the strip being flexed, and subsequently only by flexure of the said web through a limited angle substantially smaller than the dihedral angle a corresponding to the half-open condition of the door. A similar operation, but in inverse direction, takes place as the door passes from the condition of FIG. 2 to its fully unfolded (closed) condition.
The angle a in the half-open condition of the door usually amounts to about 80, as is known to experts. Consequently, in order to insure the above-described operation, the width of the slits 24, 25, as compared with the thickness of the web 19 of the strip, shall be such as to give rise to an angular play (or rotational freedom) of the strip in each of the slats through an angle substantially less than 80, preferably amounting to 40-50 (i.e. about half only, of the said angle a).
It will be readily appreciated from the above description that, owing to a limited extent of flexure of the web of the strip in the two limit-conditions of the door, the thickness of said web can be made substantially greater than in the prior structures without risk of cracking, with an additional advantage of the said strip to withstand powerful and/ or sharp pulls applied to the door in use.
In order to prevent the strip from slipping out (principally downwardly) from the slats connected therethrough, a vertically effective abutment is provided in the lower end region of one at least of the slats. In the embodiment shown in FIG. 4, cylindrical plugs P are forcibly inserted into the lower ends of the mortises 22, 23; similar plugs P can be moreover provided in the upper ends of the mortises, if desired.
Although polypropylene is an excellent material for the strip 18, other suitable flexible plastics (such as nylon, for example) can be employed, if desired.
What I claim is:
1. A folding sliding door of the type including a plurality of slats with adjacent vertical edges of the slats hinged to each other by means of a vertically extending flexible strip of plastic formed as a web having a bead on each of its longitudinal edges, each head being inserted into a mortise in the corresponding adjacent slat, the bead and mortise being of circular shape and cross sectional profile, with the improvements comprising: the beads being of lesser diameter than the mortises so that the head is freely rotatable in the mortise, a slit opening from the mortise to the edge of the slat the mortise is in, the slit being of greater dimension than the thickness of the web of the strip interconnecting the beads, but the web being of lesser dimension than the diameter of the beads, each head being freely rotatable in its associated mortise through a limited angle less than the angle of rotation necessary to allow full opening 'or closing of the door without flexing of the strip, so that a now-flexing hinge is provided between each slat, the edge of the mortises abutting the web of the interconnecting strip and flexing said strip to provide a flexing hinge between the panels in the fully opened or closed positions of the door, and an effective vertical abutment carried by the slats at the lower end of the mortise preventing the strip from slipping downwardly from the mortise.
2. A door as in claim 1 when the strip consists oi polypropylene resin having in the web section of the strip a molecular orientation substantially perpendicular to the beads in the plane of the web.
References Cited FOREIGN PATENTS 5/1961 Canada. 12/1964 Canada.