Self-supporting filter unit

Claim 2

A method according to Claim 1 characterised in that in forming the material a further land (54) is provided also in the plane of the peaks of the corrugations and extending transversely of the corrugations formed in the material, and in that in securing the portions (14) of material together the further lands (54) provided in the portions (14) are arranged in opposed relation, thus serving to close one end of the passages provided by the corrugations, and are secured together.

Claim 5

A forming assembly for forming flexible non-woven fabric sheet material to provide corrugations therein and subsequently for treating such material whilst in its corrugated configuration, characterised by a clamp arrangement having two elongated clamp members (106) each having a flat clamp surface (120), two opposed corrugating tools (102) aligned with one another such that the peaks of the corrugating surface of one tool mate with the valleys of the corrugating surface of the other, and means for effecting relative movement of approach and separation between the clamp members (106) and also between the corrugating tools (102), whereby material disposed therebetween can be formed into a corrugated configuration with a land extending parallel to the corrugations, and further characterised in that each corrugating tool comprises a plurality of elongated blade members (102), each extending parallel with the clamp members (106) and each having a material-engaging end portion of generally triangular cross-section thus to provide an elongated peak and a valley being thus formed between the peaks of adjacent blade members, and in that with a portion of sheet material held clamped by the clamp members (106) and extending between the corrugating tools (102), the means for effecting relative movement between said tools (102) is effective to advance each blade member (102) of at least one of said tools in sequence, starting with the blade member (102 d ) whose peak is most closely adjacent the clamp members (106) and thereafter the next most closely (102 b ) adjacent and so on.

Claim 6

An assembly according to Claim 5 characterised in that the blade member (102 d ; 102 b ) of each tool adjacent the clamp members (106) has a flattened surface (114; 116), said surfaces cooperating with the flattened surfaces (120) of the clamp members (106) to form two opposed continuous clamp surfaces of the width of a land to be formed in the material, and further in that the blade member (102c; 102 a ) of each tool remote from the clamp members (106) also has a flattened surface (122; 124) of corresponding dimensions to the surfaces (120) of the clamp members (106).

Claim 7

An assembly according to either one of Claims 5 and 6 characterised in that heating means (130) is provided for heating the tools (102) to a temperature at which the fabric sheet material therebetween is rendered rigid.

Claim 8

An assembly according to any one of Claims 5 to 7 characterised in that each blade member (102) has at least one flat forming face (128) extending transversely of the corrugations adjacent one end thereof whereby as the blade members (102) are moved together an edge portion of the material is clamped between the flat forming surface (128) of the cooperating blade members (102) thus progressively to form a land (54) along said edge portion.

Claim 9

Apparatus suitable for use in the manufacture of filter units from flexible non-woven fabric sheet material, characterised by a forming assembly according to any one of Claims 5 to 8, means (110) for feeding the material through the apparatus from a continuous supply, and severing means (112) for severing formed rigid portions from the material, and further characterised in that the feeding means (110) comprises cooperating members providing a complementary peak-and-valley arrangement for engaging in one or more corrugations in the formed rigid material, and means for moving the members (110) bodily through a predetermined distance equivalent to the dimension of the tools (102) as measured in the direction of feed of the material, whereby the material is fed section-by-section through the apparatus, each section comprising a plurality of configurations with a parallel land at one end thereof, and in that severing means (112) is disposed in a position such that as each section of material is fed as aforesaid a land formed as aforesaid is positioned in opposed relation with the severing means (112) and thus the section can be severed along said land.

Claim 10

A self-supporting filter unit characterised by two portions (14) of a rigid sheet material formed with corrugations and bounded at each side by a land (50), and comprising an additional land or lands (52) intermediate the side lands (50), said lands (50, 52) extending parallel to the corrugations and the portions (14) being secured together along said lands (50, 52) such that the corrugations of the portions (14) are disposed peak-to-peak whereby passages are formed thereby, said passages being defined by wall portions which are air-permeable and through which air can pass and be drawn off but which prevent the passage therethrough of dust and/or other debris, and further characterised in that each portion (14) also has a further land (54), extending transversely of the corrugations and in the plane of the peaks of the corrugations, said further lands (54) also being secured together thus to close one end of each of the passages.

Claim 11

A filter unit according to Claim 10 characterised in that at the other end of the passages each portion (14) of material has formed therein a still further land (56) extending transversely of the corrugations but in the plane of the bottoms of the valleys (30) of the corrugations, thus to form an opening into which the passages open and in which a connection member can be accommodated whereby the passages are connected to a suction source.

Claim 12

A filter unit according to Claim 10 characterised in that at the other end of the passages each portion (14) of material has formed therein a still further land (56 a ) extending transversely of the corrugations and flanged outwardly from the plane of the bottoms of the valleys (30) of the corrugations about a line passing through said bottoms, thus to form a connecting piece into which the passages open and by which the unit can be connected to a suction source.