GB2095737A

GB2095737A - Holding flexible film

Info

Publication number: GB2095737A
Application number: GB8109535A
Authority: GB
Original assignee: British Aluminum Co Ltd
Current assignee: British Aluminum Co Ltd
Priority date: 1981-03-26
Filing date: 1981-03-26
Publication date: 1982-10-06
Also published as: GB2095737B

Abstract

A method of clamping an edge region of flexible film material comprising laying the region across an open channel member having opposed side walls and distorting the region so that it follows a tortuous path within the channel and over both walls by engaging a locking bar therein, and holding the member and the bar together. <IMAGE>

Description

SPECIFICATION Holding flexible film This invention relates to a method of and apparatus for holding flexible film material in a stretched condition and is particularly although not exclusively concerned with the double glazing of glasshouses and with the provision of a more sophisticated double glazing method and apparatus for use either internally or externally on windows and which is particularly suitable for the 'do-it-yourself' market.

According to one aspect of the present invention there is provided a method of clamping an edge region of flexible film material comprising laying the region across an open channel member having opposed side walls distorting the region so that it follows a tortuous path within the member and over both walls by engaging a locking bar therewith and holding the member and the bar together.

Another aspect of the present invention comprises a method of double glazing an existing glazed structure comprising clamping the edge regions of a polygonal sheet of heat shrinkable flexible film material around the structure in accordance with the method of the preceding paragraph and heating the material to shrink it taut.

A further aspect of the present invention comprises apparatus for clamping an edge region of flexible film material comprising an open channel member with opposed side walls having inwardly turned lips at their outer ends, a locking bar of generally S- or Z-shape in cross section and having one limb of a length greater than the gap between the lips and capable of being 'threaded' through the lips until its outer end engages beneath one of the lips and clip means for holding the other limb of the bar against the other lip the arrangement being such that the edge region may follow a tortuous path extending over said one lip, along said one limb and around the other lip to extend between said other lip and the other limb.

The wall formed with said lip may extend outwardly of the base of the channel member a distance less than the other wall. The limbs of the bar are oppositely disposed and may be identical or of different widths. Preferably the other lip has a part extending outwardly of its wall and the clip engages around said part and the other limb.

The above and other aspects of the invention will now be described by way of example with reference to the accompanying drawings in which: Figs. 1 to 4 show diagrammatically in cross section a flexible film edge clamping apparatus in successive stages of operation and Figs. 5, 6 and 7 show diagrammatically in cross section different ways in which the apparatus of Figs. 1 to 4 may be used to double glaze an existing glazed structure.

Referring to Figs. 1 to 4 a channel member 1 has a base 2 and inner and outer upstanding walls 3 and 4. The wall 3 has an inturned lip 5 at its outer end and is of lesser height than the wall 4 which has a lip 6 extending both inwardly and outwardly thereof. It will be assumed that a number of such channel members are secured around the edges of a polygonal (generally rectangular) window frame 7. An S-shaped locking bar 8 is associated with each of the channel members and comprises a central stem 9 having similarly oppositely directed limbs 10 and 11 each having rounded parts 12 and 13. The length of each limb and its rounded part is slightly greater than the gap between the lips 5 and 6.

As shown in Fig. 1 a sheet 14 of heat shrinkable flexible film material such as that sold under the Registered Trade Mark 'MELINEX' has its edge region 1 5 laid over the channel member 1. The locking bar 8 has its limb 1 1 "threaded" between the lips 5 and 6 to extend within the channel member carrying the film material with it as successively shown in Figs. 2 and 3. In Fig. 3 the outer end of the limb 11 extends beneath the lip 5 and the outer part of the limb 10 lies close to the lip 6. Excess film material is cut off by the blade 16 of a knife 17 run along the outer part of the lip 6.

The film material thus follows a tortuous path extending over the lip 5, along the limb 1 1, around the part 13 and the lip 6 to extend between the latter and the outer part of the limb 10.

As shown in Fig. 4 a clip 18 which may be of extruded plastics material is sprung around the adjoining lip 6 and limb 10 and around the part 12. The clip 18 has an outer skirt 20 terminating at or near the frame 7. It will be understood that prior to engagement of the clip 18 the bar 8 must be held in place by hand.

When the sheet material has all its edge regions secured as shown in Fig. 4 it is shrunk taut by heating. In the case of small indoor areas this may be by hot air blown, for example, by a domestic hair dryer and in the case of large areas, or outdoors, this may be by using a flame thrower of the type commonly used for horticultural weed killing. It will be understood that the tortuous path followed by the material 14 through the channel member 1 effectively clamps the edge regions 15 against the tension of the shrunken film. The clip is capable of resisting the maximum tension in the film which may be 100 Ibs inch run.

The channel members 1 and the locking bars 8 are preferably extruded from aluminium alloy and the clip 18 may be of white or other selfcoloured plastics material.

Fig. 5 to 7 shows how the arrangement of the present invention may be used on the opening casement 21 of a window frame 22, the casement being conventionally glazed with a single sheet of glass 23. In Fig. 5 the channel members 1 are secured to the inner surface 24 of the casement so that the gap between the film material 14 and the glass 23 is as large as possible. As well as providing heat insulation such arrangement can also provide a measure of sound proofing. Fig. 6 shows a more unobtrusive arrangement with the channel members 1 secured to the surface 25 and in this case the gap between the film material 14 and the glass 23 is reduced. Fig. 7 shows an arrangement with the channel members 1 mounted on an external surface 26 of the casement.

Instead of using the clip 18 which substantially embraces the channel member 1 and the locking bar 8 it will be understood that a series of spaced apart U-shaped clips (not shown) may be engaged over the outer ends of the limbs 10 and the outer part of the lip 6. Such clips may be of plastics or metal, for example, stainless steel and this arrangement is particularly suitable for glasshouses.

Variations (not shown) may also be made to the shape of the locking bar 8. This may be a more simple Z-shape and may have its limb 10 wider than the limb 11.

Claims

1. A method of clamping an edge region of flexible film material comprising laying the region across an open channel member having opposed side walls distorting the region so that it follows a tortuous path within the member and over both walls by engaging a locking bar therewith and holding the member and the bar together.

2. A method of double glazing an existing glazed structure comprising clamping the edge regions of polygonal sheet of heat shrinkable flexible film material around the structure in accordance with the method of the preceding paragraph and heating the material to shrink it taut.

3. Apparatus for clamping an edge region of flexible film material comprising an open channel member with opposed side walls having inwardly turn lips at their outer ends, a locking bar of generally S- or Z-shape in cross section and having one limb of a length greater than the gap between the lips and capable of being 'threaded' through the lips until its outer end engages beneath one of the lips and clip means for holding the other limb of the bar against the other lip the arrangement being such that the edge region may follow a tortuous path extending over said one lip, along said one limb and around the other lip to extend between said other lip and the other limb.

4. Apparatus according to claim 3 in which the wall formed with said lip extends outwardly of the base of the channel member a distance less than the other wall.

5. Apparatus according to claim 3 or claim 4 in which the limbs of the bar are identical but oppositely disposed.

6. Apparatus according to any one of claims 3 to 5 in which the other lip has a part extending outwardly of its wall and the clip engages around said part and the other limb.

7. Apparatus according to any one of claims 3 to 5 in which the bar is held in position by at least one U-shaped spring clip engaging over the outer ends of said other lip and said other limb.