Method of manufacture of a pleated window shade

Abstract: Single-panel pleated shades are created through an adaptation of methods used to create cellular shades. The cellular shades are created by known methods, and are then cut longitudinally to divide them into two single-panel pleated shades. Advantages of the invention include its enhanced appearance and low cost.

Description: This invention relates to a method of manufacture of pleated window shades, in particular a single-panel pleated window shade. Several processes are known for manufacturing window shades of folded material. Two relevant basic varieties of these shades are a first, pleated type consisting of a single panel of corrugated material and a second more complex cellular type, where stacked folded strips form a series of collapsible cells. This latter type is known to have favorable thermal insulation properties, because of the static air mass which is trapped between the layers of material when the cells are in the expanded position. The single-panel type, on the other hand, is favored for its appearance in some cases, and is less expensive to manufacture. There is considerable difference in the method of manufacture of the single-panel and cellular shades. The former has heretofore been made by repeatedly folding the material across its width, so that it becomes pleated. Among the difficulties with this approach is the need repeatedly to make narrow parallel folds transversely across a wide sheet of material of continuous length. Unless highly exacting conditions are maintained, the folding process can fall out of alignment. Also, substitution of materials is cumbersome because sheets of material and not strips are involved. Further, single-panel shades are relatively weak, structurally, as compared to cellular shades. Retention of pleat shape is a significant problem with most single-panel shades, and is particularly severe where non-woven or sheer fabrics are used. Another disadvantage is the necessity of using multiple sheets joined at seams where large shades are desired. There are several methods for producing the cellular shades. For example, in U.S.-A- 4,685,986 two single-panel pleated lengths of material are joined together by adhesively bonding them together at opposing pleats. The adhesive bonding step limits the problem of pleat retention noted above with respect to pleated shades. Other methods depart from this by joining together series of longitudinally folded strips, rather than continuous sheets of pleated material, see for example US-A-4,450,027 and 4,676,855. In the former strips longitudinally folded into a U-shape are adhered on top of one another, whereas in the latter these strips are Z-shaped and are adhered in an interlocking position. The strip joining method shown in the US-A-4,450,027 has a number of desirable attributes, while providing a highly desirable thermally insulative shade. First, the alignment problems inherent in folding large sheets of material transversely to make pleated shades are largely avoided. Second, substitution of materials is easier because strips and not sheets of material are involved. Third, structural strength is increased, which gives greater pleat retention and allows for more lightweight materials to be used. Fourth, larger shades can be made without the need for seams. Finally, the speed of production of such cellular shades is at least as fast as that of single-panel pleated shades made by usual methods. According to the present invention there is provided a method of fabricating an expandable shade of a plurality of folded strips, one on top of the other, comprising the steps of: stacking in layers a plurality of folded strips of material having a central portion and two lateral edge portions folded over the central portion to form an assembly of cells one on another; applying an adhesive material to each layer to bond the central portion of each layer to the folded lateral edge portions of an adjacent layer, forming a unitary stack; and cutting the stacked folded material longitudinally along the center of the cells to create two single-panel expandable structures. Such a method of manufacture provides "pleated-look" shades of greater strength, and in particular, greater resistance to flattening of the pleats, than hereto achieved by simply pleating a sheet of material. The method is useful with a wide range of materials including non-woven and sheer materials, is suitable for forming large shades without seams and is capable of giving rapid production speed and versatile material substitution. In order that the invention may more readily be understood, the following description is given, merely by way of example, reference being made to the accompanying drawings, in which: Figure 1 is a perspective view of one embodiment of initial creasing apparatus of the present invention; Figure 2 is an enlarged cross-sectional view of a folding roller of this apparatus as it shapes the shade material; Figure 3 is a cross-sectional view of a folding track as it further shapes the shade material; Figure 4 is a perspective view of one embodiment of the adhesive applicator; Figure 5 is a perspective view of a modified adhesive applicator; Figure 6 is a perspective view of a layered cellular shade being separated into two pleated shade portions according to the present invention; Figure 7 is a perspective view of the single-panel shade material according to the present invention in its collapsed state; Figure 8 is a perspective view of a single-panel shade material according to the present invention in its expanded state; and Figures 9, 10, 11 and 12 are each a perspective view of four different embodiments of single panel shade product according to the invention. As indicated above, single-panel "pleated-look" shades may be produced according to the invention by essentially the same methods disclosed in US-A-4,450,027, with the additional step of cutting the cellular shade obtained thereby into two essentially identical panels. Figures 1 to 4 illustrate steps used in the basic method for manufacturing cellular shades. A continuous strip of shade material 10 is drawn through a series of steps which result in its edge portions 12 being folded over the central portion 13, so that they approach each other closely near the middle of the strip. As Figure 1 shows, a pair of spaced-apart creaser wheels 14 are pressed against the shade material 10 as it is drawn around a roller 16. The creaser wheels are mounted on an axle 17 which is itself mounted on a pivotal arm assembly 18, and are kept pressed against the shade material by a spring 19. After creasing, the material 10 is drawn through rollers 20, 21 which are used to bend the edges 12 of the shade material inwardly, as shown in Figure 2. The edges 12 are then folded in, over the central portion 13 of the shade material 10, by being drawn through a folding die 22, as shown in Figure 3. Once folded, adhesive material 30 is applied to the shade material, as shown in Figures 4 and 5, to bond layers of the shade material together. Generally, as the shade material 10 is drawn around a roller 32, adhesive material 30 is dispensed from an applicator 34 onto the shade material 10. Motor-driven belts 36 may be used to drive the roller 32 to assist in drawing the shade material 10. Preferably, the adhesive 30 is dispensed at a rate proportional to the speed at which the shade material 10 is drawn past, so that a like amount of adhesive 30 is applied regardless of the manufacturing rate. Figures 4 and 5 show two preferred modes of adhesive application which result in two different embodiments of the invention shown in Figures 9 and 10, respectively. In the Figure 4 embodiment, two beads 30a of adhesive 30 are continuously dispensed one each onto edges 12 of the shade material 10. The strips of material 10 are then stacked as shown in US-A-4,450,027, so that the strips 10 are bonded to one another. According to the invention, these bonded strips are subsequently cut to create two single-panel shades 40 of the type shown in Figure 9. In Figure 5, instead of the two beads of adhesive, two pairs of parallel beads 30b are applied. When the stacked strips are subsequently cut, two single-panel shades of the type shown in Figure 10 are created. As noted above, after the application of adhesive material, the shade material 10 is stacked so that the folded edge portions 12 of one strip are adhesively bonded to the central portion 13 of the next strip. In US-A-4,450,027 the strip material is stacked by being wound upon a rotating elongated mandrel, the stacked strips thus curving around the ends of the mandrel. When the assembly is complete, the curved ends of the assembly are cut off, leaving two shade panels on either side of the mandrel. The present invention adds the additional step of cutting the stacked material longitudinally down its central portion 13, between the folded side portions 12, preferably by a rotating circular knife 44, yielding two pleated panels 40, as shown in Figure 6. However, any basic cutting tool could be used, even a simple hand-held knife. These pleated panels are then used in the usual way to make finished shade products, e.g. by joining a top rail 50 and a bottom rail 52, as shown in Figures 7 and 8, in order to give the panel 40 structural rigidity. Conventional cords 60, pulleys 62, and related hardware, as shown schematically in Figures 9 and 10, may be added to provide a means for expanding and contracting the panel 40. As noted above, in the Figure 9 embodiment, one bead of adhesive 30a is used to bond each strip to the next. Typically, holes 64 are drilled so that the lift cords 60 are visible from the side of the shade meant to face into a room, as shown. In the Figure 10 embodiment, holes 64 are drilled so that the lift cords 60 are typically disposed between the beads of adhesive 30b provided. In this embodiment, the lift cords 60 are not visible from the side of the shade meant to face into a room. Two other embodiments representing variations on the manner of adhesive bonding are shown in Figures 11 and 12. Both of these use two beads of adhesive dispensed onto the strip material, as in the Figure 9 embodiment. In the Figure 11 embodiment, however, the holes 64 for the cords 60 are drilled behind the adhesive bonds 30c so that the lift cords 60 for expanding and contracting the shade 40 are not visible from the side of the shade meant to face into a room. According to the embodiment of Figure 12, the adhesive bonds 30d are relatively wide and the holes 64 for the cords 60 are drilled through the bonds. This also yields a product where the cords are not visible from the side of the shade meant to face into a room. It should also be noted that the adhesive material used, while usually liquid adhesive, may be of other varieties such as double-sided contact tape. Finally, while the preferred mode of the invention is to employ the processes disclosed in US-A-4,450,027, adding the cutting step according to the invention, and including the steps of drilling the assembly for cords and the like at specific locations with respect to the glue bond locations as needed, the invention may be used generally to divide cellular shades produced by other methods to yield two single-panel pleated shades. These other methods include all those employing different ways of creating cellular arrays of folded strips of material which are stacked and bonded to form the shade.

Claims: A method of fabricating an expandable shade (40) of a plurality of folded strips, one on top of the other, comprising the steps of: stacking in layers a plurality of folded strips of material (10) having a central portion (13) and two lateral edge portions (12) folded over the central portion to form an assembly of cells one on another; and applying an adhesive material (30) to each layer to bond the central portion (13) of each layer to the folded lateral edge portions (12) of an adjacent layer, forming a unitary stack; characterised by the further step of cutting the stacked folded material longitudinally along the centre (at 44) of the cells to create two single-panel expandable structures (40). A method according to claim 1, characterised in that the adhesive material (30) bonds the folded strip in one longitudinal line (30a, 30c, 30d) between each folded lateral edge portion (12) and the central portion (13) of the adjacent layer. A method according to claim 2, characterised in that the adhesive material is applied in one longitudinal line along each lateral edge portion of the folded material. A method according to claim 1, 2 or 3, characterised by the steps of: forming holes (64) through the stacked folded material; attaching a head rail (50) to a top folded strip and a bottom rail (52) to a bottom folded strip; and connecting at least one cord (60) to the bottom rail (52), extending through the holes (64) in the stacked folded material and into the head rail (50). A method according to claim 4, characterised in that the holes (64) are formed through the stacked folded material between the adhesive (30c) and the location where the material is cut. A method according to claim 4, characterised in that the holes (64) are formed through the stacked folded material, said holes extending essentially through the adhesive material (30d) joining the layers. A method according to claim 4, characterised in that the holes (64) are formed through the stacked folded material between the adhesive (30c) and the location where the material is folded. A method according to claim 1, characterised in that the adhesive material (30b) bonds the folded strip in two parallel longitudinal lines between each folded lateral edge portion (12) and the central portion (13) of the adjacent layer. A method according to claim 8, characterised by the further steps of: forming holes (64) through the stacked folded material between the parallel longitudinal lines of adhesive material; attaching a head rail (50) to a top folded strip and a bottom rail (52) to a bottom folded strip; and connecting at least one cord to the bottom rail, extending through the holes in the stacked folded material and into the head rail. A method according to any preceding claim, characterised in that the step of stacking the continuous strip of folded material in a plurality of adjacent layers is effected by wrapping the continuous strip over a rotating mandrel so that the continuous strip forms two or more straight sections connected by curved portions and by cutting away from the straight sections of the stacked folded material the curved portions of the stacked material.

Inventors: COLSON WENDELL B, COLSON, WENDELL B.
Applicants: HUNTER DOUGLAS INTERNATIONAL, HUNTER DOUGLAS INTERNATIONAL NV
Application year: 1990
Main classification: B29C69
IPC codes: B31D5, B32B37, B29C65, B32B5, E06B9, B29L31