Abstract: An apparatus is disclosed for providing rods formed from a continuous supply of filter material for use in the manufacture of cigarette filter elements, each rod having individual objects placed at predetermined spaced intervals along the length thereof. The apparatus comprises a first hopper configured to provide a reservoir for objects, a second hopper positioned to receive objects from the first hopper, and a reciprocating screen disposed between the first hopper and the second hopper. The reciprocating screen defines a plurality of passageways therein, and the reciprocating screen is configured to facilitate transfer of the objects from the first hopper to the second hopper. The apparatus also comprises an object insertion unit in operable communication with the second hopper and configured to introduce a plurality of objects into engagement with the continuous supply of filter material.

Abstract: Apparatus incorporating a filter tow processing unit adapted to supply filter tow to a continuous rod forming unit includes an object insertion unit that positions objects within the filter tow to manufacture a filter rod containing objects positioned at predetermined intervals. The apparatus also includes an upper hopper that acts as a reservoir for a plurality of objects, and provides for supply of objects to a lower hopper. The lower hopper is shaped so that objects are stacked therein. The bottom of the lower hopper is shaped so as to cooperate with a portion of upper region of a rotating wheel. The peripheral face of the rotating wheel incorporates a plurality of spaced pockets, each pocket being of sufficient shape and size to accommodate one object. Objects within the lower hopper are aligned in a single line along a portion of the peripheral face in the upper region of the rotating wheel. Each object then is positioned at predetermined intervals within a continuous supply of filter material.

Abstract: Cigarette filter rods having individual objects positioned at predetermined intervals therein are prepared by transferring the individual objects from a rotating horizontal pan to a rotating vertical wheel and then depositing the object into a web of filter tow. Each object is positioned within the moving web of tow. The web filter material and the objects positioned within the web are introduced into a rod-forming unit wherein the rod is formed. The rate of feed of the filter tow, the rate of rotation of the horizontal pan and the vertical wheel are controlled relative to one another such that objects are positioned at predetermined intervals along the rod. Cigarette filter elements having well controlled amounts of flavorant contained therein can be made from the rods.

Abstract: A method of manufacturing an extraction bag sheet including: (1) a step of placing and holding tags on a rotary supporting body at predetermined intervals; (2) threading a string into a continuous pattern on the circumferential surface of the rotary supporting body; (3) bonding the string to the tags; (4) supplying a water-permeable filter sheet onto the tags and the string; (5) bonding the water-permeable filter sheet to the string; and (6) bonding the water-permeable filter sheet to the tags. In the bonding steps of (3), (5), and (6), bonding heads are used which are moved reciprocally and oscillatingly about the center axis of the rotary supporting body and moved vertically relative to the circumferential surface of the rotary supporting body by an oscillation servo motor and a vertical movement servo motor.

Abstract: A method of manufacturing composite filters for cigarettes, cigars and similar tobacco products, on a twin track machine, involves generating a succession of filter sticks of a first type, made from a first filter material and/or having first filtration properties, and at least one other succession of filter sticks of a different type, made from a respective different filter material and/or having filtration properties different to those of the first type; cross-cutting the filter sticks of the first type and the filter sticks of the different type on at least one transverse cutting line to obtain a succession of first and second plugs of the first type and a succession of first and second plugs of the different type; arranging the first plugs of the first type and the first plugs of the different type in alternation one with another to create a first filter rod, and arranging the second plugs of the first type and the second plugs of the different type in alternation one with another to create a second filte

Abstract: A method of making segmented filters including moving substantially identical segments of one type at uniform rate to a transferring element, which places each segment separately on an exit path. Setting of the filter segments in a repeating group on the exit path is accomplished by delay in collecting segments by a transferring element in each module of the apparatus. Uniform positioning is effected using the transferring element which includes uniformly spaced drivers, and non-uniform positioning is effected using the transferring element with non-uniformly spaced drivers. The apparatus includes a guiding element positioned adjacent to a cutting drum and has a wall closing a channel for a set of segments drawn out of a flute on the drum. The filter set is led through the channel with the aid of a dog of a chain and is advanced by a worm surface of a pushing together drum.

Abstract: A method of folding a filter bag 10 made from a nonwoven fabric or stiff media to facilitate installation within a filter retainer basket and a folded filter bag 10 arrangement.

Abstract: Cigarette filter rods having individual objects positioned at predetermined intervals therein are prepared by transferring the individual objects from a rotating horizontal pan to a rotating vertical wheel and then depositing the object into a web of filter tow. Each object is positioned within the moving web of tow. The web filter material and the objects positioned within the web are introduced into a rod-forming unit wherein the rod is formed. The rate of feed of the filter tow, the rate of rotation of the horizontal pan and the vertical wheel are controlled relative to one another such that objects are positioned at predetermined intervals along the rod. Cigarette filter elements having well controlled amounts of flavorant contained therein can be made from the rods.

Abstract: A method of making segmented filters including moving substantially identical segments of one type at uniform rate to a transferring element, which places each segment separately on an exit path. Setting of the filter segments in a repeating group on the exit path is accomplished by delay in collecting segments by a transferring element in each module of the apparatus. Uniform positioning is effected using the transferring element which includes uniformly spaced drivers, and non-uniform positioning is effected using the transferring element with non-uniformly spaced drivers. The apparatus includes a guiding element positioned adjacent to a cutting drum and has a wall closing a channel for a set of segments drawn out of a flute on the drum. The filter set is led through the channel with the aid of a dog of a chain and is advanced by a worm surface of a pushing together drum.

Abstract: Cigarette filter rods having individual objects positioned at predetermined intervals therein are prepared by transferring the individual objects from a rotating horizontal pan to a rotating vertical wheel and then depositing the object into a web of filter tow. Each object is positioned within the moving web of tow. The web filter material and the objects positioned within the web are introduced into a rod-forming unit wherein the rod is formed. The rate of feed of the filter tow, the rate of rotation of the horizontal pan and the vertical wheel are controlled relative to one another such that objects are positioned at predetermined intervals along the rod. Cigarette filter elements having well controlled amounts of flavorant contained therein can be made from the rods.

Abstract: Cigarette filter rods having individual objects positioned at predetermined intervals therein are prepared by transferring the individual objects from a rotating horizontal pan to a rotating vertical wheel and then depositing the object into a web of filter tow. Each object is positioned within the moving web of tow. The web filter material and the objects positioned within the web are introduced into a rod-forming unit wherein the rod is formed. The rate of feed of the filter tow, the rate of rotation of the horizontal pan and the vertical wheel are controlled relative to one another such that objects are positioned at predetermined intervals along the rod. Cigarette filter elements having well controlled amounts of flavorant contained therein can be made from the rods.

Abstract: Filter elements made up of least two axially aligned plugs are advanced in succession by a feed unit along a first path and in a first direction, with the plugs oriented along a second direction transverse to the first direction, toward a garniture section extending along a second horizontal path and in a third direction, on which they are formed into at least one continuous rod which is then divided up by a rotary cutter into single composite filters. A transfer unit linking the feed unit and the garniture section comprises a conveyor, rotatable about a first axis parallel to the second direction, equipped with carriers each presenting at least one slot designed to admit one filter element; the single carriers are pivotable independently relative to the conveyor about a second axis parallel to the first axis, and about a third axis transverse to the first axis, alternating between positions in which the slot extends parallel with the second direction and with the third direction.

Abstract: Apparatus incorporating a filter tow processing unit adapted to supply filter tow to a continuous rod forming unit includes an object insertion unit that positions objects within the filter tow to manufacture a filter rod containing objects positioned at predetermined intervals. The apparatus also includes an upper hopper that acts as a reservoir for a plurality of objects, and provides for supply of objects to a lower hopper. The lower hopper is shaped so that objects are stacked therein. The bottom of the lower hopper is shaped so as to cooperate with a portion of upper region of a rotating wheel. The peripheral face of the rotating wheel incorporates a plurality of spaced pockets, each pocket being of sufficient shape and size to accommodate one object. Objects within the lower hopper are aligned in a single line along a portion of the peripheral face in the upper region of the rotating wheel. Each object then is positioned at predetermined intervals within a continuous supply of filter material.

Abstract: The present invention provides a method and apparatus for pleating paper. The apparatus includes a pair of pleating rollers, means to rotate one of said pleating rollers, a first pair of support rollers in supporting contact with a first of said pair of pleating rollers and a second pair of support rollers in supporting contact with a second of said pair of pleating rollers. Each of said pleating rollers has a plurality of radially reduced sections. An elongated pleating finger member is positioned in at least a plurality of radially reduced sections, and means are provided to movably support each of said elongated pleating finger members.

Abstract: A machine (1) for making filter bags (4) of tetrahedral shape for infusion products comprises a revolving conveyor drum (15) driven by a first drive shaft (16) to feed a web (5) of filter paper along a path (P) on which there are positioned: a station (25) for feeding the filter paper web (5); a station (21) for feeding a succession of tags (6); a station (22) for feeding tie string (7) connecting the filter bags (4) to the respective tags (6); a station (23) for arranging the tie string (7) according to a defined pattern on the path (P); and a plurality of sealers (24) facing the path (P) to attach the tie string (7) and the tags (6) to the filter paper web (5).

Abstract: A pleating apparatus comprises a support surface, first and second pleating surfaces, and a driver for compressing a portion of a filter material between the first and second pleating surfaces to form a pleat, where at least one of the pleating surfaces is curved or extends at an acute angle with respect to a support surface.

Abstract: A filter is made by the folding of a filter media to pleats after the application of strings of glue thereon and the glue serves as distance elements and fixing for the filter media. The glue contains an expandable filler, that when heated expands to a larger size that is then permanent. When the glue has set the filter is heated and the filler expands and expands the filter pleats.

Abstract: A machine (1) for making filter bags (4) of tetrahedral shape for infusion products comprises a revolving conveyor drum (15) driven by a first drive shaft (16) to feed a web (5) of filter paper along a path (P) on which there are positioned: a station (25) for feeding the filter paper web (5); a station (21) for feeding a succession of tags (6); a station (22) for feeding tie string (7) connecting the filter bags (4) to the respective tags (6); a station (23) for arranging the tie string (7) according to a defined pattern on the path (P); and a plurality of sealers (24) facing the path (P) to attach the tie string (7) and the tags (6) to the filter paper web (5).

Abstract: Cigarette filter rods having individual objects positioned at predetermined intervals therein are prepared by transferring the individual objects from a rotating horizontal pan to a rotating vertical wheel and then depositing the object into a web of filter tow. Each object is positioned within the moving web of tow. The web filter material and the objects positioned within the web are introduced into a rod-forming unit wherein the rod is formed. The rate of feed of the filter tow, the rate of rotation of the horizontal pan and the vertical wheel are controlled relative to one another such that objects are positioned at predetermined intervals along the rod. Cigarette filter elements having well controlled amounts of flavorant contained therein can be made from the rods.

Abstract: A pleating method comprises disposing a filter material on a support surface and compressing a portion of the filter material between first and second pleating surfaces to form a pleat, where at least one of the pleating surfaces is curved or extends at an acute angle with respect to a support surface.

Abstract: A filter making apparatus includes a positioning device having a passageway therethrough, with the passageway guiding a continuous flavor element such as a continuous strand of textile material from an inlet of the passageway to an outlet of the passageway. A liquid flavorant is introduced into the passageway at a desired flow rate and the strand of material carries the supplied liquid flavorant out of the positioning device at a rate substantially equal to the desired flow rate. A portion of the passageway can form a bath of the liquid flavorant supplied to the passageway through a separate inlet at approximately atmospheric pressure. A portion of the positioning device guides the continuous strand of material through the bath, or guides the strand to pass along the bottom of the passageway, and the saturated or partially saturated strand of material then exits from an outlet of the passageway to a point in the path of filter tow material that is being converged to form a filter rod.

Abstract: A patch plug is provided that facilitates field installations thereof, e.g., using conventional equipment such as a conventional punch tool. Preferred patch plugs according to the present disclosure include a cover and a housing, each of which includes a hinge member to facilitate relative rotations of portions of the housing and cover. Rotational/pivotal motion of the cover and the housing relative to the disclosed hinge members facilitates establishing electrical connection with terminals positioned therewithin. The terminals that may be positioned in alternating pairs to provide improved return loss, and printed circuit boards are provided for further improved performance.

Abstract: A filtration media array is provided having at least one contoured polymeric film layer having surface structures. The film layers may be configured as a stack that has the contoured film layer defining a plurality of ordered inlet openings through a face of the stack and corresponding air pathways, thereby forming an open, porous volume. The air pathways may be defined by a plurality of flow channels formed by the contours of the structured contoured film layers.

Abstract: A method of folding a gas bag for a vehicle occupant restraint system comprises the following steps: first, the gas bag is unfolded between a base and an opposing surface. A spacing is provided between the base and the opposing surface, which corresponds to a height of a housing into which the gas bag is to be inserted after folding. Then, a folding funnel is provided which comprises one end having a large cross-section and one end having a small cross-section, the large cross-section being larger than or equal to a cross-section of the gas bag when unfolded between the base and the opposing surface, and the small cross-section corresponding to a cross-section of the housing; beginning with its large cross-section. Finally, the folding funnel is placed over the unfolded gas bag and moved relative thereto such that the gas bag is pushed together on the base by the folding funnel to the small cross-section.

Abstract: A filter element 10 for purifying fluids having a filter medium 11, an enclosure member 12, and a rod 13. The filter medium 11 has folds 14, which may be zigzag-shaped, and which define a fold height 15 and a pleat surface 16. At right angles to folds 14 extend end faces 17, which represent the course of the folds 14. The enclosure members 12 are arranged on the end faces 17. To support the folds 14, the rod 13 pierces through the pleat surfaces 16 of the folds 14 creating joints 19. These joints 19 are sealed, e.g., by additional seals or by fusing the filter medium to the support rod or the support rod to the filter medium.

Abstract: A filter includes a cylindrical pleated filter element having a longitudinal axis, an inner and outer periphery, first and second end surfaces, and a plurality of longitudinal pleats. First and second end elements are sealingly arranged with the first and second end surfaces, wherein at least one of the end elements is an open end element. The filter element is a pleated composite that includes a filter medium, an upstream drainage medium and a downstream drainage medium. Each pleat includes a crown, a root, and a pair of legs. The legs of each pleat are joined to one another at the crown of the pleat and are joined to the legs of adjacent pleats at the root of the pleat. Each pleat leg abuts an adjacent pleat leg along the inner periphery of the filter element and the pleats extend from the inner periphery in a curved, an arcuate, an angled, or a straight nonradial direction to the outer periphery.

Abstract: An apparatus for sequentially forming folds in a sheet of paper which is continuously moving substantially in a single plane. A first fold is formed in the center of the continuously-moving sheet of paper and subsequent pairs of folds are sequentially formed, one on each side of the previously-formed folds, until the entire continuously-moving sheet is folded. Guide wires retain each folded section until the entire sheet is folded by the cyclic upward movement of a continuous flexible wire loop held for free movement on a pair of spaced apart pulley assemblies. Each pulley assembly includes a plurality of evenly spaced pulleys each of which are held for free rotation on a support frame. Each support frame is driven in rotation about a central axis of rotation. Each individual pulley includes a freely rotatable ring surrounding the periphery of the pulley around which the flexible wire loop is held.

Abstract: A method is disclosed for forming a filter cartridge which includes the steps of providing a cylindrical filter element having a plurality of radially extending longitudinal pleats, engaging an outer periphery of the cylindrical filter element along a substantial portion of the length thereof, and simultaneously moving the plurality of radially extending longitudinal pleats into a laid-over spiraled configuration along the entire length of the cylindrical filter element to form a spiral pleated filter element. An apparatus is also disclosed for effectuating the disclosed method.

Abstract: A system for pleating a continuous strip of foldable material including feeding the strip of foldable material between adjacent flights of cooperatively positioned endless conveyors having pleat folding arms pivotally associated therewith which are alternatively and interfittingly positioned to pleat the strip of foldable material as it movingly passes from one end of adjacent flights to the other end thereof.

Abstract: A method for the manufacture of filters in which a filter material in the rm of a continuous web is pre-embossed, perforated with a laser beam, and then pleated. The pleated filter element is fixed in a subsequent operation in an apparatus and the perforated scrap areas and are removed from the filter element.

Abstract: A method is disclosed for forming a filter cartridge which includes the steps of providing a cylindrical filter element having a plurality of radially extending longitudinal pleats, engaging an outer periphery of the cylindrical filter element along a substantial portion of the length thereof, and simultaneously moving the plurality of radially extending longitudinal pleats into a laid-over spiraled configuration along the entire length of the cylindrical filter element to form a spiral pleated filter element. An apparatus is also disclosed for effectuating the disclosed method.

Abstract: A filter includes a cylindrical filter element having a longitudinal axis, first and second end surfaces, and a plurality of longitudinal pleats. Each of the pleats has a pair of legs with first and second surfaces. The pleats are in a laid-over state in which the first surface of each leg is in intimate contact with the first surface of an adjoining leg and the second surface of each leg is in intimate contact with the second surface of an adjoining leg over substantially the entire height of each leg and over a continuous region extending for at least approximately 50% of the axial length of the filter element. An impervious end cap is connected to the first end surface of the filter element.

Abstract: An apparatus for assembling a filter having a peripheral frame and at least one filter media component includes a continuous conveyor for feeding a plurality of filter frames, in succession, to a plurality of workstations, each filter frame having a closed periphery with a generally upstanding leading flap, side flaps and a trailing flap, the workstations including: a) a first station including at least a pair of tools located so as to engage and open the side flaps; b) a second station including a media component supply roll, a cutter adapted to cut a predetermined length of media component; guide elements adapted to guide the cut length of media component for movement away from the cutter; and a reciprocable carriage adapted to receive the cut length of media component, the carriage having a motive drive adapted to accelerate forwardly to a position where the carriage is located directly above an opened filter frame on the conveyor; and forward and rearward flippers adapted to open the leading and trailing

Abstract: A method for making a pleated structure having a pleated shape memory includes providing an elongated material having a longitudinal axis; pleating the material to form a pleated structure having a plurality of substantially parallel pleats substantially parallel to the longitudinal axis; folding the material along a plurality of axes substantially perpendicular to the longitudinal axis to form folds and provide a folded structure defining wall portions between the folds and face portions at the folds; heating the material in the pleated structure so as to provide a heated material; and cooling the heated material so as to provide the material with shape memory toward the pleated structure.

Abstract: A beverage filter formed of porous paper, or other paper-like filter material for placement in the ground beverage container of a beverage brewing apparatus, such as a percolating coffee pot, in which the filter is graduated by being provided with indicia in the form of one or more of lines, colored lines, numerals and words, such indicia being affixed on the interior of such filter for readily viewing by the user. In the preferred embodiment, such indicia are affixed in at least two arrangements, one for a mild brew and one for a strong brew. Each arrangement includes markings or indicia for ground beverage level according to the volume of brew desired, such as by cups of coffee, for example. A user, utilizing any dispensing means including the ground beverage container itself, need simply fill the filter to the line corresponding to the desired volume at the desired strength.

Abstract: A filter plug feeding apparatus comprises a pair of hoppers in which charcoal and plain filter rods are stored, a pair of hopper drums for delivering charcoal and plain filter rods from the hoppers, respectively, the hoppers being able to discharge the filter rods in a manner such that the axial centers of the filter rods are situated individually on feeding lines for their corresponding hopper drums and the delivered filter rods being cut into a pair of filter half rods on the hopper drums, a separation drum for separate a pair of charcoal half rods received from one hopper drum, an assembly drum for receive the pair of charcoal half rods the from the separation drum and a pair of plain half rods from the other hopper drum, and rotary knives detachably attached to the assembly drum and capable of cutting each of the charcoal half rod into a pair of charcoal plugs.

Abstract: A filter includes a cylindrical filter element having a longitudinal axis, first and second end surfaces, and a plurality of longitudinal pleats. Each of the pleats has a pair of legs with first and second surfaces. The pleats are in a laid-over state in which the first surface of each leg is in intimate contact with the first surface of an adjoining leg and the second surface of each leg is in intimate contact with the second surface of an adjoining leg over substantially the entire height of each leg and over a continuous region extending for at least approximately 50% of the axial length of the filter element. An impervious end cap is connected to the first end surface of the filter element.

Abstract: A filter includes a cylindrical filter element having a longitudinal axis, first and second end surfaces, and a plurality of longitudinal pleats. Each of the pleats has a pair of legs with first and second surfaces. The pleats are in a laid-over state in which the first surface of each leg is in intimate contact with the first surface of an adjoining leg and the second surface of each leg is in intimate contact with the second surface of an adjoining leg over substantially the entire height of each leg and over a continuous region extending for at least approximately 50% of the axial length of the filter element. An impervious end cap is connected to the first end surface of the filter element.

Abstract: A coreless filter comprises a pleated, spirally wound loop of material disposed in a housing. The loop includes a layer of filter material, such as a membrane filter, interposed between two support layers.

Abstract: A helically wound tube made of at least two sheets of preperforated flat roll paper material. Each sheet is helically wound in edge abutting relation such that one longitudinal edge of the sheet abuts the other longitudinal edge of the sheet to form a ridgeless seam. Some of the perforations of the subsequently wound sheets overlap some of the perforations of the previously wound sheets to form a reinforced cylindrical tube having perforations that permit radial flow through the cylindrical tube.

Abstract: Apparatus for use in a filter assembly operation wherein filter components are seated within a filter frame such that the frame has a generally upstanding leading flap, side flaps and a trailing flap. The apparatus includes side flap engaging members adapted to push the pair of side flaps outwardly to provide clearance necessary to close the leading and trailing flaps. A stationary ski member located downstream of the side edge engaging members is adapted to close the leading edge, and a retractable ski member located at least partially upstream of the retractable side flap engaging members is adapted to close the trailing flap, thereby permitting the side flaps to be subsequently closed in at least partially overlapping relationship with the leading and trailing flaps. A related method is also disclosed.

Abstract: A coreless filter comprises a pleated, spirally wound loop of material disposed in a housing. The loop includes a layer of filter material, such as a membrane filter, interposed between two support layers.

Abstract: A vacuum cleaner bag is treated with a dual component, antimicrobial composition which reduces harmful bacteria and fungi safely and effectively. The vacuum cleaner bag is used on an upright vacuum cleaner and includes a porous cloth body which is treated with the dual component, antimicrobial composition.

Abstract: A double-chamber tea bag has a centerfold that is crimped by squeezing it between a toothed wheel and a plain wheel and a headfold in which the front chamber has a flap that folds over the part of the end of the front chamber between triangular folds at each corner.

Abstract: A filter element and a method for manufacturing the filter element is disclosed wherein filter paper is folded in a zigzag manner to form a filter material, and a circumferential portion of the filter material is fastened by an adhesive so as to fasten the zigzag filter material and to divide the filter material into a dust side and a clean side. Thus, the structure of the filter element is simplified and a filter performance is enhanced.

Abstract: A filter unit is made of two portions (14) of rigid corrugated material secured together along lands (50,52) extending parallel with the corrugations and, if desired, intermediate them, and also along lands (54) formed along one end of the corrugations, thus closing the passages formed when the two portions (14) are secured together. Suitable fastenings are adhesive bonding, and metallic fasteners, e.g. eyelets, or stitching. Further flanges (56) may be provided for facilitating a connection with a suitable suction or other air-drawing source; also if desired, such further lands (56) may be out-flanged for facilitating such connection. Apparatus for forming the sheet material is also provided whereby material from a continuous supply is progressively formed between two sets of blade members (102), the blade members being moved sequentially and alternately (as between the two sets) into forming engagement with the sheet material.

Abstract: An improved method for the continuous fabrication of filter units for use in automotive air bag inflators by spirally winding a hollow cylindrical core, at least one filter layer, and an outer layer to form a continuous spirally wound filter unit. The continuous spirally wound filter unit is then cut into individual filter unit of desired length by the use of conventional cutting device.

Abstract: A filter device including a separable housing and cannister-like means, with the improved filter element retained in the latter. The filter element being an elongated tapered strip having a predetermined transverse dimension at its midsection generally equivalent to the diametral measurement of the interior of said cannister and the initial configuration of the tapered sides being equated to the various chordal dimensions of the interior of the cannister-like means integrated with the folds of the filter element, thereby providing a filter element of controllable increased filtration area.

Abstract: A filter cartridge for use in a fluid filtering system, constructed to induce rotational flow in the unfiltered fluid, includes a pleated filter sleeve in which the individual sleeves are slanted relative to the sleeve circumference in a direction opposite to the direction of the rotational flow fluid. The slanted pleats can be constructed by creasing a sheet of filter media at alternatingly shorter and longer widths to form pleats having relatively shorter front legs and relatively longer back legs. The shorter front legs bias the pleats in the counter-rotational direction. Apparatus for manufacturing the pleated sleeve includes a pleater roll having pleater wires spaced to form the alternatingly shorter and longer pleat widths.

Abstract: A filter insert of nonwoven material in the form of a pleated pack is self-supporting and consists of thermally weldable nonwoven (1). Each of the two outside ends (3) of the pleated pack (2) is hemmed by the nonwoven material (1) forming the pleats, which is folded over in the same direction and at the same time is fixed in tight contact to the corresponding folded of the adjacent pleat end. At the same time the nonwoven material projects beyond the near crease of the adjacent pleat end by 0.5 to 1.5 times the pleat spacing. For manufacture, the flat filter material (1) is first pleated and then a defined pleat spacing (7) is produced by drawing it apart to a limited extent. Then the two outside edges (8) of the pleated pack are gripped between comb-like tools (9) entering pincer-wise into the pleating at top and bottom, leaving the filter material projecting beyond the tools on each side by 1.5 to 2.5 times the pleat spacing (7).