Fluted filter medium and process for its manufacture

A fluted filter medium (74) comprising a corrugated filter sheet, where each flute (120) has an end closure defined by a regular fold arrangement in the corresponding corrugation. Each regular fold arrangement has at least four folds. A process for manufacturing the fluted filter medium comprising deforming a portion of each corrugation to define at least one foldable tip, and folding the said tip in order to close the corrugation.

This application is being filed as a U.S. National Stage Application of PCT International Application Number PCT/US2003/002799 in the name of Donaldson Company, Inc., a U.S. national corporation and resident, (Applicant for all countries except US); Patrick Golden, a U.S. resident and citizen (Applicant for US only); Gregory L. Reichter, a U.S. resident and citizen (Applicant for US only) and Daniel T. Risch, a U.S. resident and citizen (Applicant for U.S. only), which was filed on 31 Jan. 2003, designating all countries and claiming priority to U.S. 60/395,009 filed 10 Jul. 2002.

FIELD OF THE DISCLOSURE

The present disclosure relates to filter media for use in filtering liquids or gases. The disclosure particularly relates to such media that utilizes a corrugated structure, to define filtration flutes or surfaces. Specifically, the disclosure relates to techniques for modifying such flutes in selected portions thereof, and to resulting structures.

BACKGROUND

Fluid streams, such as air and liquid, carry contaminant material therein. In many instances, it is desired to filter some or all of the contaminant material from the fluid stream. For example, air flow streams to engines for motorized vehicles or for power generation equipment, gas streams to gas turbine systems and air streams to various combustion furnaces, carry particulate contaminant therein that should be filtered. Also liquid streams in engine lube systems, hydraulic systems, coolant systems or fuel systems, carry contaminant, that should be filtered. It is preferred for such systems, that selected contaminant material be removed from (or have its level reduced in) the fluid. A variety of fluid filter (air or liquid filter) arrangements have been developed for contaminant reduction. In general, however, continued improvements are sought.

SUMMARY

The present disclosure concerns folded flute ends of fluted filter media, and to techniques for folding. It also concerns preferred filter arrangements constructed utilizing media having flutes with folded ends.

A variety of methods for folding media are described herein. In general, a common feature to each is that the media folding includes a step of deforming a media flute, typically through an indentation or projection against an outside surface of the flute. Follow up folding steps cause preferred folded configurations to result.

A portion of this disclosure is based upon, and priority is claimed to, U.S. provisional application Ser. No. 60/395,009, filed Jul. 10, 2002. In that priority document, a preferred folded or darted media configuration was shown, along with a process for forming the preferred configuration. In general, the process involved directing an indentation pin arrangement against a ridge of a corrugation.

In addition to the disclosure of U.S. provisional application Ser. No. 60/395,009 contained herein, there are provided additional techniques applicable to provide preferred fold arrangements. Certain of these techniques are generally referred to as “supported” processes, methods or techniques and relate to supporting a portion of the flute in the vicinity of the deformation. In addition, preferred arrangements for providing flute support during deformation, are described.

DETAILED DESCRIPTION

I. Media Configurations Using Corrugated Media, Generally

Fluted filter media can be used to provide fluid filter constructions in a variety of manners. One well known manner is as a z-filter construction. The term “z-filter construction” as used herein, is meant to refer to a filter construction in which individual ones of corrugated, folded or otherwise formed filter flutes are used to define sets of parallel longitudinal inlet and outlet filter flutes for fluid flow through the media. Some examples of z-filter media are provided in U.S. Pat. Nos. 5,820,646; 5,772,883; 5,902,364; 5,792,247; 5,895,574; 6,210,469; 6,190,432; 6,350,296; 6,179,890; 6,235,195; Des. 399,944; Des. 428,128; Des. 396,098; Des. 398,046; D437,401.

One particular type of z-filter media, utilizes two specific media components joined together, to form the media construction. The two components are: a corrugated (or fluted) sheet; and, a non-corrugated (or facing) sheet. The corrugated (or fluted) media and non-corrugated (or facing) sheet together, are used to define the parallel inlet and outlet flutes. In some instances, the corrugated sheet and non-corrugated sheet are secured together and are then coiled to form a z-filter media construction. Such arrangements are described, for example, in U.S. Pat. Nos. 6,235,195 and 6,179,890. In certain other arrangements, some non-coiled sections of corrugated media secured to flat media, are stacked on one another, to create a filter construction. An example of this is described in FIG. 11 of U.S. Pat. No. 5,820,646.

The term “corrugated” used herein to refer to structure in media, is meant to refer to a structure resulting from passing the media between two corrugation rollers, i.e., into a nip or bite between two rollers each of which has surface features appropriate to cause a corrugation affect in the resulting media. The term “corrugation” is not meant to refer to flutes that are folded or otherwise formed by techniques not involving passage of media into a bite between corrugation rollers. However, the term “corrugated” is meant to apply even if the media is further modified or deformed after corrugation, for example by the folding techniques described herein.

Corrugated media is a specific form of fluted media. Fluted media is media which has individual flutes (for example formed by corrugating or folding) extending thereacross.

Serviceable filter element configurations utilizing z-filter media are sometimes referred to as “straight through flow configurations” or by variants thereof. In general in this context what is meant is that the serviceable filtered elements generally have an inlet flow face and an opposite exit flow face, with flow entering and exiting the filter cartridge in generally the same straight through direction. The term “serviceable” in this context is meant to refer to a media containing filter cartridge that is periodically removed and replaced from a corresponding fluid cleaner.

The straight through flow configuration is in contrast to serviceable filter cartridges such as cylindrical pleated filter cartridges of the type shown in U.S. Pat. No. 6,039,778, incorporated herein by reference, in which the flow generally makes a turn as its passes through the serviceable cartridge. That is, in a U.S. Pat. No. 6,039,778 filter the flow enters the cylindrical filter cartridge through a side, and then turns to exit through an end face (in forward-flow systems). In reverse-flow systems, the flow enters the serviceable cylindrical cartridge through an end face and then turns to exit through a side of the filter cartridge. An example of a reverse-flow system is shown in U.S. Pat. No. 5,613,992, incorporated by reference herein.

An example of a typical prior art z-filter media construction is shown inFIGS. 1-4.FIG. 1is based on the disclosure of prior art U.S. Pat. No. 5,820,646, atFIG. 1.FIG. 2is an enlarged end view of an inlet end portion of a straight through flow filter element using a media construction made with the media shown inFIG. 1.FIG. 3is an enlarged end view of and analogous toFIG. 2, but of an opposite, outlet, end.FIG. 4is an enlarged, schematic, view of a combination of corrugated sheet and non-corrugated sheets.

The term “z-filter media construction” and variants thereof as used herein, is meant to refer to any or all of: a web of corrugated or otherwise fluted media secured to non-corrugated (facing) media with appropriate sealing to allow for definition of inlet and outlet flutes; or, such a media coiled or otherwise constructed or formed into a three dimensional network of inlet and outlet flutes; and/or, a filter construction including such media.

Referring toFIG. 1, the z-filter media construction1depicted comprises a corrugated sheet3, and a non-corrugated sheet4secured to one another. The corrugated sheet3is secured to the non-corrugated sheet4such that individual flutes or corrugations7(comprising ridges7aand troughs7bwhen viewed toward side3aof sheet3) extend across the non-corrugated sheet4between opposite ends or edges8and9. For the final product, it is a matter of choice whether end (or edge)8or end (or edge)9is the upstream end or edge. For purposes of the following discussion, it will be assumed that edge8is chosen to be the upstream edge and edge9is chosen to be the downstream edge, in the resulting filter media construction. Thus, arrows10indicate the direction of fluid flow, during filtering.

Referring toFIG. 1, the corrugated sheet3has first and second opposite sides or surfaces3a,3b. The second side3bis the side directed toward the non-corrugated sheet4, during initial assembly of the corrugated sheet3/flat sheet4combination as discussed below; i.e., when the corrugated sheet3is first brought into contact with the non-corrugated sheet4. At the upstream edge8, flutes11defined by troughs7bof the corrugations7above the corrugated sheet3, i.e., at side3aof sheet3are open to fluid flow therein in the direction of arrows12, along the upstream edge8, but are closed to fluid flow therefrom along the downstream edge9, by barrier14, in this instance sealant14a. On the other hand, flutes15, defined by corrugations7aon the opposite side3bof the corrugated sheet3from flutes11, are closed to entrance of fluid therein along the upstream edge8, by barrier16, in this instance sealant16a, but are open to fluid flow outwardly therefrom, along edge9, by the absence of any sealant at this location.

Of course in the arrangement ofFIG. 1, the media is shown not secured in an overall three-dimensional filter element cartridge structure, that would complete creation of the isolated parallel flutes11,15. This is shown in fragmentary, schematic, inFIG. 2. Referring toFIG. 2, the media construction1is now shown configured in an overall three-dimensional media pack20. In general media pack20, for the embodiment shown, would comprise the media construction1ofFIG. 1, coiled about itself to create a cylindrical fluted-construction21. A complete drawing would typically show a circular or obround filter body. InFIG. 2, only a portion of such a coiled construction21is depicted, in particular a portion when viewed toward an upstream surface22. Herein the term “upstream” when used in this or similar contexts to refer to a surface or edge, is meant to refer to the surface or edge toward which fluid is directed, for a filtering process. That is, the upstream surface or edge is the surface or edge at which the fluid to be filtered enters the z-filter construction21. Analogously, the term “downstream” when used to refer to an edge or surface, is meant to refer to the edge or surface of a construction21from which filtered fluid exits the filtered media construction21, during use.

It is noted that inFIGS. 2 and 3, the flutes11,15are depicted schematically, as if they have triangular, cross-sections, for simplicity. The actual curved shape ofFIG. 1would be present in the actual filter.

Referring toFIG. 2, at upstream edge8or along upstream surface22, the fluid flow openings in inlet flutes11are generally indicated by the absence of barrier or sealant. Thus inlet flutes11are open to the passage of fluid flow therein. The closed upstream ends of exit flutes15are also shown, by the presence of a barrier, in this instance sealant. Thus, fluid flow directed against upstream surface22can only pass into the media construction20, for filtering, by entering the inlet flutes11. It is noted that in some instances, at the upstream edge8, the outlet flutes may not be sealed immediately at the edge8, but rather may be sealed by a sealant spaced inwardly from the edge8, a portion of the way down the length of the corresponding flute. An example of this is shown, for example, in U.S. Pat. No. 5,820,646, at FIG. 16 thereof. In general, the inlet end of an exit flute will be considered sealed, as long as the sealant or other structure closing the flute is located (relative to edge8) either at the edge or no more than 25% (preferably no more than 10%) of the distance between the upstream edge8and the opposite downstream edge9. Usually the sealing is at the edge8. The description “no more than 25% (or 10%) of the distance between the upstream edge and the opposite downstream edge9” in this context is meant to include sealing at edge8.

Referring toFIG. 3, the exit edge9of the media, forming exit end or23of the filter construction21. The exit flutes15are shown open, and the inlet flutes11are shown closed by barrier or sealant. The inlet flutes11will be considered sealed at the downstream ends, as long as the sealant material or other structure closing the flute, is at the exit edge9, or within a distance from the edge9corresponding to no more than 25% of the distance between the opposite edges8and9. For typical, preferred, embodiments the sealed end of each flute8,9would be sealed by sealant positioned at a location within a distance from the closest edge of no more than 10% of the flute length from edge8to edge9. Usually the sealing is at the edge9. The description “no more than 25% (or 10%) of the flute length from edge8to edge9” in this context, is meant to include sealing at edge9.

In general, the corrugated sheet3,FIG. 1is of a type generally characterized herein as having a regular, curved, wave pattern of flutes or corrugations. The term “wave pattern” in this context, is meant to refer to a flute or corrugated pattern of alternating troughs7band ridges7a. The term “regular” in this context is meant to refer to the fact that the pairs of troughs and ridges (7b,7a) alternate with generally the same repeating corrugation (or flute) shape and size. (Also, typically each trough7bis substantially an inverse of each ridge7a.) The term “regular” is thus meant to indicate that the corrugation (or flute) pattern comprises troughs and ridges with each pair (comprising an adjacent trough and ridge) repeating, without substantial modification in size and shape of the corrugations along at least 70% of the length of the flutes. The term “substantial” in this context, refers to a modification resulting from a change in the process or form used to create the corrugated or fluted sheet, as opposed to minor variations from the fact that the media sheet3is flexible. With respect to the characterization of a repeating pattern, it is not meant that in any given filter construction, an equal number of ridges and troughs is present. The media could be terminated, for example, between a pair comprising a ridge and a trough, or partially along a pair comprising a ridge and a trough. (For example, inFIG. 1the media1depicted in fragmentary has eight complete ridges7aand seven complete troughs7b.) Also, the ends of the troughs and ridges may vary from one another. Such variations in ends are disregarded in the definitions.

In the context of the characterization of a “curved” wave pattern of corrugations, the term “curved” is meant to refer to a corrugation pattern that is not the result of a folded or creased shape provided to the media, but rather the apex7aof each ridge and the bottom7aof each trough is formed along a radiused curve. A typical radius for such z-filter media would be at least 0.25 mm and typically be not more than 3 mm.

An additional characteristic of the particular regular, curved, wave pattern depicted inFIG. 4, for the corrugated sheet3, is that at approximately a midpoint30between each trough and each adjacent ridge, along most of the length of the flutes, is located a transition region where the curvature inverts. For example, viewing face3a,FIG. 1, trough7bis a concave region, and ridge7ais a convex region. Of course when viewed toward face3b, trough7bof side3aforms a ridge; and, ridge7aof face3a, forms a trough.

A characteristic of the particular regular, curved, wave pattern corrugated sheet shown inFIGS. 1-4, is that the individual corrugations are generally straight. By “straight” in this context, it is meant that through at least 70%, typically at least 80% of the length between edges8and9, the troughs do not change substantially in cross-section. The term “straight” in reference to corrugation pattern shown inFIGS. 1-4, in part distinguishes the pattern from the tapered flutes of corrugated media described in FIG. 1 of WO 97/40918. The tapered flutes of FIG. 1 of WO 97/40918 would be a curved wave pattern, but not a “regular” pattern, or a pattern of straight flutes, as the terms are used herein.

For the particular arrangement shown herein inFIG. 1, the parallel corrugations are generally straight completely across the media, from edge8to edge9. However, herein embodiments are shown in which straight flutes or corrugations are deformed or folded at selected locations, especially at ends. Again, modifications at flute ends are generally disregarded in the above definitions of “regular,” “curved” and “wave pattern.”

Attention is again directed toFIG. 3in which media pack20is depicted from a viewpoint directed toward downstream end23defined by edge9of the z-filter media construction1. At this end or surface23, the exit flutes15are depicted open and unsealed, and the entrance flutes11, are shown closed by a barrier, in this case, by sealant. Thus, the only way fluid can exit from downstream end23is by flow outwardly from an open exit flute15.

As a result of the above described construction, fluid which enters the inlet face22can only exit from the opposite exit face23, if the fluid has passed through the filter media3,4. This, in general, is a characteristic of a z-filter media construction in use namely: (a) individual generally parallel flutes are defined by a media, for example corrugated media; and, (b) a closure pattern is provided closing exit flutes at the upstream end and closing inlet flutes at the downstream end, forcing fluid flow (with filtering) through one of the media sheets in order for the fluid to exit from the media pack.

In typical applications involving z-filter media, the media is either surrounded by an impermeable shell (as in U.S. Pat. No. 5,820,646), or seals are used at appropriate locations, or both, to prevent fluid flow from going around the media, from a fluid inlet to a fluid outlet.

Attention is again directed toFIG. 4, which is an enlarged, fragmentary, schematic, end view of the Z-filter media construction1, showing the corrugated sheet3and the non-corrugated sheet4, but not barrier or sealant. Again, the configuration of the corrugated sheet, inFIG. 4, will sometimes be referred to herein as a regular, curved, wave pattern of straight flutes.

Z-filter constructions which do not utilize straight, regular curved wave pattern corrugation shapes are known. For example in Yamada et al. U.S. Pat. No. 5,562,825 corrugation patterns which utilize somewhat semicircular (in cross section) inlet flutes adjacent narrow V-shaped (with curved sides) exit flutes are shown (seeFIGS. 1 and 3, of U.S. Pat. No. 5,562,825). In Matsumoto, et al. U.S. Pat. No. 5,049,326 circular (in cross-section) or tubular flutes defined by one sheet having half tubes attached to another sheet having half tubes, with flat regions between the resulting parallel, straight, flutes are shown, see FIG. 2 of Matsumoto '326. In Ishii, et al. U.S. Pat. No. 4,925,561 (FIG. 1) flutes folded to have a rectangular cross section are shown, in which the flutes taper along their lengths. Finally, in WO 97/40918 (FIG. 1), flutes or parallel corrugations which have a curved, wave patterns (from adjacent curved convex and concave troughs) but which taper along their lengths (and thus are not straight) are shown.

Before proceeding further with this description, the nature of the filter media is briefly discussed. In general the filter media is a relatively flexible material, typically a non-woven fibrous material (of cellulose fibers, synthetic fibers or both) typically including a resin therein, sometimes treated with additional materials. Thus, it can be conformed or configured into the various folded or corrugated patterns, without unacceptable media damage. Also, it can be readily coiled or otherwise configured for use, again without unacceptable media damage. Of course, it must be of a nature such that it will maintain a corrugated or folded configuration, during use.

In the corrugation process, an inelastic deformation is caused to the media. This prevents the media from returning to its original shape. However, once the tension is released the flute or corrugations will tend to spring back, recovering only a portion of the stretch and bending that has occurred. Thus, facing (noncorrugated) sheet is tacked to the fluted sheet, to inhibit this spring back.

Also, in general the media contains a resin. During the corrugation process, the media can be heated to above the glass transition point of the resin. When the resin then cools, it will help to maintain the fluted shapes.

Both of these techniques are generally known in practice, with respect to the formation of corrugated media.

An issue with respect to z-filter constructions relates to closing of the individual flute ends. In many instances a sealant or adhesive is provided, to accomplish the closure. As is apparent from the discussion above, in typical z-filter media, especially that which uses straight flutes as opposed to tapered flutes, large sealant surface areas (and volume) at both the upstream end and the downstream end are needed. High quality seals at these locations are critical to proper operation of the media structure that results. The high sealant volume and area, creates issues with respect to this. In addition, the relatively large, impermeable surface area to fluid flow represented by the sealant areas, generally positioned perpendicular to flow through the media pack, create restriction to fluid flow.

With respect to a particular configuration of straight fluted media, Yamada, et al. suggest addressing this issue at the downstream end of the media, by flattening the two media sheets together into a parallel configuration, see FIGS. 1 and 4 of Yamada, et al, U.S. Pat. No. 5,562,825. Yamada, et al.FIG. 4is depicted herein asFIG. 5, without reference numerals. A flattening such as that found in Yamada, et al., leads to less sealant volume due to the crushing and potentially less leakage through the sealant, due to the compression.

In the disclosure of WO 97/40918, incorporated herein by reference, it was suggested that this sealant or closed volume/area issue could be addressed (at least with media having a regular, curved, wave pattern) by crushing along a sealant bead and then slitting.

A reference which generally shows a different type of crushing of flutes is U.K. 703,823, published Feb. 10, 1954.

Attention is now directed toFIG. 6, in which a z-filter media construction40utilizing a regular, curved, wave pattern corrugated sheet43, and a non-corrugated flat sheet44, is depicted. The distance D1, between points50and51, defines the extension of flat media44in region52underneath a given corrugated flute53. The length D2of the arcuate media for the corrugated flute53, over the same distance D1is of course larger than D1, due to the shape of the corrugated flute53. For a typical regular shaped media used in fluted filter applications, the linear length D2of the media53between points50and51will generally be at least 1.2 times D1. Typically, D2would be within a range of 1.2-2.0, inclusive. One particularly convenient arrangement for air filters has a configuration in which D2is about 1.25-1.35×D1. Such media has, for example, been used commercially in Donaldson Powercore™ Z-filter arrangements. Herein the ratio D2/D1will sometimes be characterized as the flute/flat ratio or medium draw for the corrugated media.

In the corrugated cardboard industry, various standard flutes have been defined. For example the standard E flute, standard X flute, standard B flute, standard C flute and standard A flute.FIG. 49, attached, in combination with Table A below provides definitions of these flutes.

Donaldson Company, Inc., (DCI) the assignee of the present disclosure, has used variations of the standard A and standard B flutes, in a variety of filter arrangements. These flutes are also defined inFIG. 49and Table A.

Of course other, standard, flutes definitions from the corrugated box industry are known.

In general, standard flute configurations from the corrugated box industry can be used to define corrugation shapes or approximate corrugation shapes for corrugated media. Comparisons above between the DCI A flute and DCI B flute, and the corrugation industry standard A and standard B flutes, indicate some convenient variations.

It should be apparent that once the length D2of the corrugated media53exceeds D1substantially, for example becomes 1.2 D1or larger, accomplishing a consistent parallel squeeze or configuration such as that shown at the downstream edge in Yamada, et al.,FIG. 4herein, will be difficult, especially with significant line speeds (30 meters per minute or more). This is in part because there is often too much media in the corrugation53to line up evenly and in parallel with the flat media44in region52to achieve the configuration shown herein inFIG. 5, (i.e. in FIG. 4 of Yamada et al. U.S. Pat. No. 5,562,825).

In general, Donaldson Company, the assignee of the present disclosure, has determined that when the relationship between the flutes of corrugation sheet and the flat sheet is such that the flute/flat ratio or medium draw is at least 1.2 (i.e. the corrugation length (D2) is at least 1.2 times the linear flat sheet length (D1) in the region of closure, in some instances it is preferred to generate a regular fold pattern, to collapse the corrugation (flute) toward the flat sheet, and to reduce the sealant area at or near flute ends. By the term “regular fold pattern” in this context, it is meant that selected corrugated (flute) ends that are modified are folded into a regular and repeated pattern, as opposed to merely being crushed toward the flat sheet. One such regular fold pattern is illustrated herein inFIG. 15, and a method for generating it is described in commonly assigned U.S. provisional application 60/395,009, filed Jul. 10, 2002, to which priority is claimed. Such a fold pattern will generally be referred to herein as a “center darted” or “center dart” fold pattern, since it results from creating, a dart or indentation (deformation) at or near an apex of each flute, to be closed, with a follow-up step of folding. A pattern of fold steps that accomplishes this is discussed below in connection withFIGS. 7-24, and also in connection withFIGS. 28-47.

Herein, an end of a flute or corrugation will be characterized as closed by a “fold” or as being “folded” if it includes at least two creases therein, each crease resulting in a portion of the media being folded back on or over itself. The fold pattern inFIG. 15has four such creases, discussed below. Preferred configurations include at least four folds or creases. The term “fold” is intended to be applicable, even if, when the media is folded back over itself, some structure or material, such as sealant, is positioned between adjacent layers of media.

II. The Folding Technique Described in U.S. Provisional Application 60,395,009, filed Jul. 10, 2002

A. Overview of Process and Resulting Darted Flute

InFIG. 7, one example of a manufacturing process for making center darts is shown schematically at60. In general, the non-corrugated sheet64and the corrugated sheet66having flutes68are brought together to form a media web71. The darting process occurs at station70to form center darted section72located mid-web. After the darting process, the z-filter media or Z-media74can be cut along the center darted section72to create two pieces76,77of Z-media74, each of which has an edge with a set of corrugations having folded ends.

Still referring toFIG. 7, it is noted that the process depicted generally involves formation of darts through folds occurring on a mid-line73of an associated media web71. Such a process will be generally characterized herein as a “mid-web folding” or “mid-web darting” process. This is to distinguish from an edge folding or edge darting process, described below. Of course, the mid-web folding process shown inFIG. 7is used to generate edge folds, once the web71is slit along fold line73.

The process of deforming the flutes68, as part of generating a regular fold pattern, takes place at station70. The folding process shown, in general, involves inverting the ridges80of the flutes68and then pressing (or folding) the inverted ridges80against the non-corrugated sheet64to form the center darted section72. In the embodiment shown, there are at least two rollers or wheels shown generally at70that are used to work the corrugated sheet66. An indenting, inverting, or darting wheel84operates first to deform or invert the ridges80, while a folder wheel86later presses or folds the inversions made by the darting wheel84into the non-corrugated sheet64to form the darted section72.

FIG. 7also shows an optional manipulation to the corrugated sheet66before encountering the darting wheel86. The optional media manipulation includes engagement with a creaser wheel88. The optional creaser wheel88engages the flutes68by initially nicking or temporarily deforming by pressing inwardly the ridges80toward the uncorrugated sheet64. This can help to start the process of deformation and to help the flutes68to be appropriately deformed (inverted) by the darting wheel86.

After engagement with the folder wheel86, the step of cutting the Z-media74is shown. A splitter, blade or cutter is shown at90dividing the Z-media74into pieces76,77.

Still in reference toFIG. 7, before the Z-media74is put through the darting station70, the Z-media74is formed. In the schematic shown inFIG. 7, this is done by passing a flat sheet of media92through a pair of corrugation rollers94,95. In the schematic shown inFIG. 7, the flat sheet of media92is unrolled from a roll96, wound around tension rollers98, and then passed through a nip or bite102between the corrugation rollers94,95. The corrugation rollers94,95have teeth104that will give the general desired shape of the corrugations after the flat sheet92passes through the nip102. After passing through the nip102, the flat sheet92becomes corrugated and is referenced at66as the corrugated sheet. The corrugated sheet66is routed to the darting process70.

The type of corrugation provided to the corrugation media is a matter of choice, and will be dictated by the corrugation or corrugation teeth of the corrugation rollers94,95. A preferred corrugation pattern will be a regular curved wave pattern corrugation, of straight flutes, as defined herein above. In some instances the techniques may be applied with curved wave patterns that are not “regular” and do not use straight flutes. A typical regular curved wave pattern used, would be one in which the distance D2, as defined above, in a corrugated pattern is at least 1.2 times the distance D1is defined above. In one preferred application, typically D2=1.25-1.35×D1.

Still in reference toFIG. 7, the process also shows the non-corrugated sheet64being routed to the darting process station70. The non-corrugated sheet64is depicted as being stored on a roll106and then directed to the corrugated sheet66to form the Z-media74. The corrugated sheet66and the non-corrugated sheet64are secured together at some point in the process, by adhesive or by other means (for example by sonic welding).

The process60shown inFIG. 7can be used to create the center darted section72.FIGS. 8-10show one of the flutes68after initial deformation; e.g., after engaging the indenting or darting wheel84and before engaging the folder wheel86. The darting wheel84deforms a portion69of the ridge80, by indenting or inverting it. By “inverting” and variants thereof, it is meant that the ridge80is indented or turned inward in a direction toward the non-corrugated sheet64.FIG. 9is a cross-sectional view along the mid-point of the inversion110created by the darting wheel84. The inversion110is between a pair of peaks112,114that are created as a result of the darting process. The peaks112,114together form a flute double peak116. The peaks112,114in the flute double peak116have a height that is shorter than the height of the ridge80before inversion.FIG. 10illustrates the cross-section of the flute68at a portion of the flute68that did not engage the darting wheel84, and thus was not deformed. As can be seen inFIG. 10, that portion of the flute68retains its original corrugated shape.

The particular process illustrated inFIGS. 7-24, is one of “center indenting,” “center inverting,” “center darting” or “center deformation.” By the term “center” in this context, again, it is meant that the indentation or inversion occurred at an apex or center of the associated ridge80, engaged by the indenting or darting wheel84. A deformation or indent will typically be considered herein to be a center indent, as long as it occurs within 3 mm of the center of a ridge.

Again, herein the term “crease,” “fold,” or “fold line” are meant to indicate an edge formed by folding the media back on or over itself, with or without sealant or adhesive between portions of the media.

Attention is now directed toFIGS. 11-15.FIGS. 11-15show sections of the darted section72after engagement with the folder wheel86.FIG. 15, in particular, shows an end view of the darted section72, in cross-section. A fold arrangement118can be seen to form a darted flute120with four creases121a,121b,121c,121d. The fold arrangement118includes a flat first layer122that is secured to the non-corrugated sheet64. A second layer124is shown pressed against the flat first layer122. The second layer124is preferably formed from folding opposite outer ends126,127of the first layer122.

Still referring toFIG. 15, two of the folds or creases121a,121bwill generally be referred to herein as “upper, inwardly directed” folds or creases. The term “upper” in this context is meant to indicate that the creases lie on an upper portion of the entire fold120, when the fold120is viewed in the orientation ofFIG. 15. The term “inwardly directed” is meant to refer to the fact that the fold line or crease line of each crease121a,121b, is directed toward the other.

InFIG. 15, creases121c,121d, will generally be referred to herein as “lower, outwardly directed” creases. The term “lower” in this context refers to the fact that the creases121c,121dare not located on the top as are creases121a,121b, in the orientation ofFIG. 15. The term “outwardly directed” is meant to indicate that the fold lines of the creases121c,121dare directed away from one another.

The terms “upper” and “lower” as used in this context are meant specifically to refer to the fold120, when viewed from the orientation ofFIG. 15. That is, they are not meant to be otherwise indicative of direction when the fold120is oriented in an actual product for use.

Based upon these characterizations and review ofFIG. 15, it can be seen that a preferred regular fold arrangement118according toFIG. 15in this disclosure is one which includes at least two “upper, inwardly directed, creases.” These inwardly directed creases are unique and help provide an overall arrangement at which the folding does not cause a significant encroachment on adjacent flutes. These two creases result in part from folding tips112,114,FIG. 9, toward one another.

A third layer128can also be seen pressed against the second layer124. The third layer128is formed by folding from opposite inner ends130,131of the third layer128. In certain preferred implementations, the non-corrugated sheet64will be secured to the corrugated sheet66along the edge opposite from the fold arrangement118.

Another way of viewing the fold arrangement118is in reference to the geometry of alternating ridges80and troughs82of the corrugated sheet66. The first layer122includes the inverted ridge110. The second layer124corresponds to the double peak116that is folded toward, and in preferred arrangements, folded against the inverted ridge110. It should be noted that the inverted ridge110and the double peak116, corresponding to the second layer124, is outside of the troughs82on opposite sides of the ridge80. In the example shown, there is also the third layer128, which extends from folded over ends130,131of the double peak116.

FIGS. 12-14show the shape of the flute68at different sections.FIG. 14shows an undeformed section of the flute68. The inversion110can be seen inFIGS. 12 and 13extending along from where it engages the non-corrugated sheet64(FIG. 15) to a point where it no longer exists (FIG. 14). InFIGS. 12 and 13, the inversion110is spaced at different lengths from the non-corrugated sheet64.

B. Specific Example From Provisional Application 60/395,009

FIG. 16illustrates one embodiment of creaser wheel88that is optionally used with the process70. As can be seen inFIG. 7, when used, the creaser wheel88is oriented such that its axis of rotation136is oriented parallel to the flute direction. This means that the creaser wheel88rotates in a plane that is in a direction transverse to the flute length. In reference again toFIG. 16, the creaser wheel88depicted is shown with its axis of rotation136passing centrally therethrough. The creaser wheel88is generally tapered at opposite surfaces137,138from a central region139adjacent to the central axis136extending to an end region140. The end region140is narrow, when compared to the width across the creaser wheel88at central region139. In the example shown, the end region140is less than one-half the width across the creaser wheel88at the central region139. In many embodiments, the width across the end region140is less than one-third of the width across the central region139. In the example embodiment illustrated, the tapered surfaces137,138are tapered at an angle α less than 10°, at least 1°, and in the particular example, 3-6°.

The creaser wheel88is optionally used to initially nick the flute68. In particular, the creaser wheel88rotates about the axis136in the direction of movement of the corrugated sheet66. The end region140contacts the ridges80of the corrugated sheet66and presses the ridges80in a direction toward the non-corrugated sheet64.FIGS. 17-19show a cross-section of the Z-media74after contact with the creaser wheel88. A creaser indent is shown at142. The ridge80can be seen to be pushed toward the non-corrugated sheet64after contact with the end region140of the creaser wheel88. InFIG. 19, it can be seen that the indent142may, in some instances, form a generally flat portion144extending between opposite sides146,147of the flute68. Thus, in the example shown, the creaser wheel88flattens the ridge80toward the non-corrugated sheet64.

In typical preferred application of the techniques described, as the ridge80is folded toward the non-corrugated sheet64, it will also be sealed to the non-corrugated sheet. One approach to accomplishing this sealing is through use of a sealant.

InFIGS. 17-19an area of sealant150is shown. In an example process, a bead of sealant150is applied between the non-corrugated sheet64and the corrugated sheet66upstream of the creaser wheel88. The indent142is placed along a portion of the flute68that is above the area of sealant150. In other words, troughs82that are adjacent to the ridge80that is put in contact with the creaser wheel88are secured to the non-corrugated sheet64with the sealant150.

Attention is next directed toFIGS. 20 and 21. One particular embodiment of an indenting or darting wheel84is shown at160. The darting wheel160shown includes a plurality of indentation picks or teeth162extending radially from a surface164of the wheel160. In the example embodiment shown, and in reference toFIG. 7, in general, the darting wheel84rotates in a direction that is parallel to the flute direction. This means that the darting wheel84rotates in a plane that is generally transverse to the direction of the flutes.

Turning again to the example darting wheel160depicted inFIG. 20, the teeth162are preferably uniformly spaced about the radial surface164. The teeth162are spaced to correspond to the particular geometry of the corrugated sheet66. That is, the spacing between adjacent ridges80of the corrugated sheet66is a primary factor in spacing between the adjacent teeth162. The number of teeth162used is also a function of the diameter of the darting wheel160. In the example shown, the darting wheel160includes at least 50, no greater than 200, and typically 100-150 teeth162. In the specific example shown inFIG. 20, there are 120 teeth162. In a typical implementation, the darting wheel160has a diameter from the tip of one tooth162to another tooth162of at least 8 inches (20.3 cm), no greater than 12 inches (30.5 cm), typically 9-10 inches (22.9-25.4 cm), and in one example about 9.7 inches (24.6 cm). However, variation from this is possible.

In the embodiment shown, each of the teeth162has a crown164that is smooth and curved. The rounded shape to the crown164helps to deform the flutes68without tearing the corrugated sheet66. The radius of the teeth162may often typically be at least 0.005 inch (0.01 cm), no greater than 2.0 inch (5.1 cm), typically 0.75-1.25 inch (1.9-3.2 cm), and preferably about 1.0 inch (2.54 cm). The thickness of each tooth is shown at dimension168. The dimension168, for the example shown, is at least 0.01 inch (0.03 cm), no greater than 0.05 inch (0.13 cm), and typically 0.02-0.04 inch (0.05-0.1 cm). The height of each tooth162is shown inFIG. 21at dimension170. The height170, in some implementations, is at least 0.05 inch (0.13 cm), no greater than 0.5 inch (1.3 cm), and typically 0.1-0.3 inch (0.25-0.76 cm).

Each tooth162has a pair of sides171,172, between which the crown164extends. The length of the tooth162between the sides170,171is at least 0.2 inch (0.5 cm), no greater than 1 inch (2.54 cm), and typically 0.5-0.7 inch (1.3-1.8 cm).

InFIG. 22, the darting wheel160is shown located between a pair of fluted rollers176,178. The fluted rollers176,178are, in some instances, driven by the movement of the corrugated sheet66along the process70. The fluted rollers176,178help to keep the darting wheel160on-center with the flutes68. As can seen inFIG. 22, the fluted rollers176,178include flutes or corrugations180that will mesh with the corrugated sheet66.FIG. 22shows the rollers176,178only partially corrugated. It should be understood that, in practice, the rollers176,178are often fully corrugated.

In reference again toFIGS. 8-10, these figures illustrate one of the flutes68after engaging the darting wheel84, for example, the darting wheel160. In processes wherein the sealant bead150is applied upstream of the darting wheel84, after contact with the darting wheel84, the ridge80forms inversion110to extend toward and to touch or engage the sealant bead150. This helps to hold the inversion110and the double peak116in place for the folder wheel86. InFIG. 9, the inversion110is shown in engagement with the sealant bead150but not in engagement with the non-corrugated sheet64. In some implementations, the inversion110can be pushed fully through the sealant bead150into touching engagement with the non-corrugated sheet64.

FIGS. 23 and 24illustrate one example of folder wheel86. The example of the folder wheel86inFIGS. 14 and 15is depicted at185. The folder wheel185functions to press the flute double peak116against the non-corrugated media64and against the inversion110to form darted section72.

In reference again toFIG. 7, the folder wheel86rotates about a central axis188that is generally parallel to the direction of the flutes68. As such, the folding wheel86rotates in the same general plane as creaser wheel88(if used) and darting wheel84; that is, folding wheel86rotates in a plane that is generally transverse to the direction of the flutes68.

In reference again toFIGS. 23 and 24, the folder wheel185has a smooth, blunt surface190for engaging the corrugated sheet66. The surface190, in example embodiments, is a toroidal surface on a radius R of at least 1 inch (2.54 cm), no greater than 3 inches (7.6 cm), and typically 1.5-2.5 inches (3.8-6.4 cm).

The folder wheel185has opposite axial surfaces192,194. The distance between the axial surfaces192and194generally defines the thickness of the folder wheel185. In example embodiments, this thickness is at least 0.1 inch (0.25 cm), no greater than 0.5 inch (1.3 cm), and typically 0.2-0.4 inch (0.5-1.0 cm). The diameter of the example folder wheel185is at least 3 inches (7.6 cm), no greater than 10 inches (25.4 cm), and typically 5-7 inches (12.7-17.8 cm). The surfaces between each of the axial surfaces192,194and the blunt surface190is curved, and in the illustrated embodiment, is on a radius r of at least 0.02 inch (0.05 cm), no greater than 0.25 inch (0.6 cm), and typically 0.08-0.15 inch (0.2-0.4 cm).

C. Example Media Section and Elements

FIG. 25illustrates a perspective, schematic view of z-media74after being modified by indenting and folding to include the darted section72, and after being separated into pieces76,77by the cutter90,FIG. 7. The folded flutes120can be seen at the downstream edge196. The air to be cleaned flows in at the upstream edge198as shown at arrows199. The air flows through the Z-media74at the upstream edge198, through the media, and then exits in the region200between the darted (folded) flutes120and the non-corrugated sheet64.

FIGS. 26 and 27illustrate example filter elements utilizing Z-media74having folded flutes120. InFIG. 26, the Z-media74with the folded flutes120is wound into filter element202. The filter element202includes opposite flow faces203,204that, in this instance, are parallel. In alternate configurations, one of the flow faces203or204may not lie in a single plane, e.g., it may be conical. An example of a conically shaped filter element with z-media is shown in U.S. Des. 399,944; U.S. Des. 428,128; and U.S. Des. 396,098 and z-media with folded flutes can be configured analogously. The flow face203is shown schematically, with only portions showing end flutes205, but it should be understood that the entire filter face203will typically have end flutes205. In use, fluid to be filtered enters the upstream flow face (in this instance204) and exits downstream flow face, in this instance,203). The fluid generally flows in the same direction entering the upstream flow face204as it exits the downstream flow face203. Again, this configuration generally referred to herein as a “straight through flow” filter.

As can be seen inFIG. 26, the particular filter element202is round, in that it has a circular cross-section. When using the filter element202in an air cleaner system, the filter element202may be modified by placing an appropriate gasket or other type of sealing members thereon. One example sealing gasket208is shown secured to an outer cylindrical surface209of the element202. The sealing gasket208shown includes foamed polyurethane and forms a seal with a housing by compression of the gasket208against the housing. Examples of usable sealing gaskets include the ones described in U.S. Pat. No. 6,190,432 and U.S. patent application Ser. No. 09/875,844, filed Jun. 6, 2001, and commonly assigned hereto.

FIG. 27illustrates another example of a filter element216utilizing z-media74and wound into the filter element216. As with the filter element202shown inFIG. 26, the filter element216has opposite flow faces217,218to accommodate straight through gas flow. As with theFIG. 26embodiment, this embodiment also shows the flow face217schematically, with only portions showing end flutes, but it should be understood that the entire filter face217typically will show the end flutes. In this embodiment, the filter element216is obround. Specifically, this particular filter element216has a cross-section in the shape of two parallel sides219,220joined at their ends by curved portions221,222. The filter element216may include appropriate sealing members or gaskets, and in the example shown, includes the type of sealing member224described in U.S. Pat. No. 6,190,432. This sealing member224includes polyurethane molded on a frame, secured to the element216. In each of the elements202,216, a central core226,227is shown as having the z-media74wound therearound. In some embodiments, the filter elements202,216can be coreless. By “coreless,” it is meant that the elements are absent a central mandrel, tube, stick, or other piece that the z-media74is wound around.

D. Example System

The filter media described herein can be made into elements, of which examples are shown inFIGS. 26 and 27. The filter elements are useable in fluid (liquid or air) cleaners. One such system is depicted schematically inFIG. 27Agenerally at230. InFIG. 27A, equipment232, such as a vehicle, having an engine233, with some defined rated air flow demand, for example, at least 300 cfm, for example 500-1200 cfm, is shown schematically. Equipment232can include a bus, an over-the-highway truck, an off-road vehicle, a tractor, or marine equipment such as a powerboat. The engine233powers the equipment232, through the use of an air and fuel mixture. InFIG. 27A, the air flow is shown drawn into the engine232at an intake region235. An optional turbo236is shown in phantom, as optionally boosting the air intake into the engine233. An air cleaner240having a filter construction242is upstream of the engine232and the turbo236. In general, in operation, air is drawn in at arrow244into the air cleaner240and through the primary element242. There, particles and contaminants are removed from the air. The cleaned air flows downstream at arrow246into the intake235. From there, the air flows into the engine233to power the equipment232.

Other examples of useable systems include intake air filters gas turbine systems. Of course the media can also be used in liquid (for example oil (lubrication), fuel or hydraulic) filters.

III. Selected Improved Techniques for Generating Folds in Corrugated Media

The techniques described in U.S. provisional application 60/395,009, can be used to form a regularly folded or regular fold pattern, to generate folds, darts or regular gathers at the ends of selected flutes of fluted or corrugated media (especially regular, curved wave pattern corrugated media) in a discontinuous or a continuous process. However with a continuous process, especially as line speed increases, for example at rates from about 30 meters per minute on up, the flexible nature of the corrugated media makes quality control for generation of the regular fold, increasingly difficult. While this in part due to timing issues with respect to the conduct of the deformation step, conducted with the darting or indentation wheel84,FIG. 7, it is also a function of the flexible nature of the media and a difficulty of ensuring that the indent or dart is not only centered at or near the apex of the corrugation media, but that the corrugation shape itself does not lean in either the upstream or the downstream (machine) direction. Improved techniques that address these issues are described in this section.

A. General Principles

Referring again toFIG. 6, and in particular to corrugation53, in general surface53aof a ridge53, (in this instance directed away from the non-corrugated sheet44) will sometimes be referred to as the “outside” surface of the ridge53; and, opposite surface53b, which is in the trough of corrugation53(and in this instance faces sheet44) will sometimes be referred to as the “inside” surface of the corrugation53. In general, a folding or darting step for a center darting of the type described above, involves deformation or indentation (in a portion of a ridge53) directed inwardly; i.e., from the outside surface53atoward the inside surface53b. When the corrugated sheet43is secured to a noncorrugated sheet44, the indentation will in many instances be toward flat sheet44such that, eventually, a portion of surface53bengages the flat sheet44(or sealant on the flat sheet44). For example, such an approach was described above to provide the structure ofFIG. 15. However, alternatives, for example as described below in connection withFIG. 48are possible.

For certain of the folding techniques generally characterized herein, a step in the folding process is providing a deformation (in the instance ofFIG. 15an indentation) in outside surface53a,FIG. 6, by directing a pin arrangement or similar construction against surface53ain the general direction of arrow55,FIG. 6. This type of deformation step has generally been referred to as an “indentation step” or “darting step,” as explained above in connection withFIG. 7and wheel or roller84.

In general, two techniques have been found useful to facilitate generation of a regular fold in corrugated media. These two techniques are:1. Preferred supporting and containing a flute of the flexible corrugation material, during the deformation process; and2. Utilization of a moveable (retractable/projectable) tooth or indentation pin arrangement, timed to project outwardly at a selected time and location, to provide a preferred deformation (preferably an indent or initial dart).

A variety of techniques can be utilized to accomplish these preferred processes. For example, containment and support can be provided by supporting the flute or corrugation (during deformation) from: (a) a location outside the corrugation (flute); (b) a location inside the corrugation (flute); or (c) both. The latter approach, in which the corrugation (flute) is supported on both the inside and the outside during the deformation process, will generally be referred to herein as an encapsulation approach, or by variants thereof.

Schematic depictions of examples of each of these three approaches are illustrated inFIGS. 28-30. InFIG. 28, an approach is shown in which the support is provided along a same side (outside) of a corrugation to be folded closed, as a side against which the indenter dart or indentation pin arrangement will press, with the support provided immediately adjacent opposite sides of the indentation pin arrangement. InFIG. 29, an approach is shown in which support is provided on a side (inside) of the corrugation opposite from that against which the indentation pin arrangement will press to start the deformation, again with support provided adjacent opposite sides of the indentation pin arrangement. Finally, inFIG. 30an encapsulation process is shown, in which support for the corrugation to be folded is provided both inside and outside of the corrugation, in each instance adjacent opposite sides of the indentation pin arrangement.

Herein in the context of the previous paragraph, the term “adjacent opposite sides of the indentation pin arrangement” and variants thereof, is meant to refer to the location of the support relative to where the indentation pin arrangement engages the corrugation to cause inversion. The term is meant to indicate that the support is located longitudinally, along the length of longitudinal extension of the corrugation, at least at the same longitudinal location as the location at which the indentation pin arrangement contacts the corrugation, except offset to the side of the corrugation location (typically ridge) where indentation contact occurs. This will sometimes be referenced as being indenting a corrugation that is supported at a region longitudinally adjacent where indentation will occur. This will be apparent from the detailed descriptions below. InFIG. 28regions395,396, indicate this type of support. It is in contrast to the arrangement ofFIG. 7, in which there was either no support to the corrugation at all, or any support to the corrugation was located spaced, longitudinally, along the length of the corrugation, away from the darting pin or indentation pin contact location.

Referring toFIG. 28, reference numeral370generally indicates the fluted or corrugated media. In the instance ofFIG. 28, the corrugated media370has a regular, curved, wave pattern for the corrugation371, with straight flutes. Although the techniques described herein were particularly developed for managing such corrugations, the techniques described herein are not specifically limited to such applications, unless otherwise stated.

InFIG. 28, a particular corrugation371to be folded is indicated. In general, the initial folding step is conducted by a deformation or indentation pin arrangement (not shown) applied in the general direction of arrow375to an outside or convex side376(from the viewpoint of the arrow375) to form an indent or deformation. For the particular embodiment shown, the deformation pin is directed against the convex side (outside)376of the corrugation371in such a manner that: the corrugation371is first engaged by the pin arrangement at or along an apex376a; and, such that the indentation force applied by the deformation pin arrangement is generally directed in a direction normal or orthogonal to a plane377adefined by troughs377on opposite sides of apex376a. It is noted, however, that variations from this, are possible.

Referring still toFIG. 28, corrugation371is supported and contained, for the darting process, by form380. The form380is depicted in phantom, inFIG. 28. Form380is generally and preferably configured to have a corrugated portion381configured to have a surface382generally defined as an inverse of the convex or outside surface371a(of corrugation371). Thus, the form380is preferably configured to mate or mesh with the corrugations of the media. Although a perfect mesh or mate is not required, it will be preferred to have as much engagement as possible, to provide maximum support. The form380is preferably rigid, not flexible like the media of the corrugation371. The form380, for example, may comprise metal or a hard plastic.

Further, form380includes gap383therein, through which the darting or indentation pin arrangement can project, in the direction of arrow375, to engage corrugation371. Preferably gap383is positioned aligned with a portion of ridge376a.

When it is said that the corrugation is “supported and contained”, for the outside darting process, it is meant that during the indentation or darting process, the indentation or darting pin projects adjacent the support so that the corrugation is supported, along its longitudinal length, at the same longitudinal location as the darting occurs, but offset to the side. Corrugation support which occurs immediately on opposite sides of, or adjacent, the indentation pin, as characterized above, would be a specific form of indentation which occurs in a corrugation that is supported and contained for the darting process. In particular, it would be a form in which there is support on both “sides” of the indentation pin, as the indentation pin projects through a gap in the support. The term “sides” in the previous sentence meaning in the directions of double headed arrow384,FIG. 28, from gap383.

With the construction shown, when the darting pin arrangement is directed through gap383in the direction of arrow375against outside surface371a of corrugation371(and when form380is present as shown inFIG. 28), the flexible media370in the region of corrugation371is contained between points388and390, against deformation either in the direction of arrow391or in the direction arrow392. This will help ensure that the flexible corrugated media370is contained and does not deform undesirably, during the indentation step. Again, the support is provided, in part, at regions395,396.

In general, a corrugation will be considered “supported and/or contained” by a support form380, if either: (a) the form380contains the corrugation by contact with the corrugation at or near troughs377on opposite sides of the corrugation; or (b) the form380extends over the corrugation to cover a distance of the height (H1ofFIG. 6) of the corrugation which is at least 10% of the height (H1); or (c) both. Typically both are used and the extension will be at least 20% of the height (H1), preferably at least 30% of the height (H1), most preferably at least 90% (for example 100%) of the height (H1). That is, if surface381of form380,FIG. 28, extends from apex376adownwardly toward plane377aa distance of at least 10% of H1, the corrugation will be considered supported by the form380. Again, typically the height or extent of support, in the direction of H1, will be at least 90% of H1, typically 100% of H1.

A variety of techniques and configurations can be used to define and provide form380. A particular approach, usable with continuous manufacturing processes, is described herein below, especially in connection withFIG. 36.

Attention is now directed toFIG. 29. InFIG. 29, a corrugated (fluted) sheet400is depicted. Corrugated (fluted) sheet400comprises a regular, curved, wave pattern corrugation401of straight flutes. InFIG. 29a particular corrugation or flute405is depicted, to be folded in a folding process initiated with an indentation pin arrangement directed toward convex (outside) surface407, for example at apex407a, under force in the general direction of arrow408.

For the particular arrangement shown inFIG. 29, the indentation pin arrangement is directed toward an apex407aof the convex surface407, in the direction of arrow408with force directed generally normal to, or orthogonal to, a plane409defined by troughs410, on opposite sides of the corrugation405. Variations from this, however, are possible.

Corrugation405is shown supported inside (i.e. along a concave surface411) by form412. Form412includes a central recessed region413therein, to receive a depression or indent in corrugation405from the indentation pin arrangement. Form412also includes sides414and415generally defined to conform with a shape of corrugation405in regions405aand405b, respectively. As with the arrangement inFIG. 28, the form or support412ofFIG. 29will generally keep the flexible media400centered with respect to an indentation pin arrangement directed thereagainst. The form412, of course, is preferably constructed from a rigid material.

Herein, a corrugation will be considered supported along the inside as long as the support form along the inside extends, from plane409toward apex407a, at least 10% of the peak height (H1ofFIG. 29). Typically the inside support will extend at least 20%, preferably at least 30%, of H1. A typical example would be 40%-60% of H1.

As with the embodiment ofFIG. 28, for the form412to be considered to support the corrugation405, it is not required that the form412have an outer surface along sides414,415, which has a shape in perfect match to the corrugation shape at these locations. However a configuration as close as possible to a matching shape, is preferred.

Also as withFIG. 28, the support inFIG. 29is at least is at regions416,417, longitudinally adjacent where indentation will occur.

Attention is now directed toFIG. 30. InFIG. 30an extension of corrugated media430is depicted. The corrugated media430shown is generally a regular, curved, continuous wave pattern corrugation arrangement431with straight flutes. Corrugation435is shown positioned for a folding process to be initiated, by an indentation pin arrangement directed against convex surface437of corrugation435in the direction of arrow438. InFIG. 30, corrugation435is shown encapsulated, between outside or outer form440, shown in phantom, supporting outside435a, which generally corresponds to form380,FIG. 28; and, inner form441(against inside surface435b), which generally corresponds to form412,FIG. 29. The term “encapsulated” and variants thereof, when used in this context, is meant to refer to a corrugation such as corrugation435, which is contained along both the convex (outside) and the concave (inside) surfaces, in the vicinity of the indentation pin (preferably on opposite sides of the indentation pin arrangement or darting pin at the same longitudinal location along the length of the corrugation435) during indentation pin arrangement (or darting pin) projection into the media. Similarly to the embodiments ofFIGS. 28 and 29, as a result of the containment, in this particular instance by encapsulation, the corrugation435will remain centered and will not undesirably move during the initiation of the folding process.

In an arrangement in which the length D2(FIG. 6) of the corrugation is approximately 1.2-1.4 times D1, it may be convenient to utilize as the indentation pin arrangement, a single indentation or darting pin directed against the apex of the corrugation, with the pin being on the order of 0.7-0.8 mm thick, and on the order of 5 mm to 40 mm wide. On the other hand, when the length D2is greater than about 1.4 times D1, it may be desirable to either use a wider indentation pin arrangement, or multiple indentation pin blades, to accomplish the desired indentation step of the folding process.

In many manufacturing applications, it will be preferred to fold the corrugated media after it has been tacked or otherwise secured to the non-corrugated media. In Section II above, an example of darting or folding process was shown, with such a combination, that was conducted at a location spaced from the edges of the media, and located generally centrally along a continuous web of corrugated media attached to non-corrugated media. Such an approach was characterized as mid-web folding and as leading to formation of edge darting, by slitting the resulting folded or darted combination, down the center of the dart. An application of this technique but using outside support for the flutes during indentation is illustrated herein schematically inFIG. 31.

Referring toFIG. 31, a schematic depiction of a typical manufacturing process is shown. In general, a corrugating station is shown at500, with two corrugated rollers501,502positioned to form a corrugating bite503therebetween. A non-corrugated media sheet506is shown directed into the bite503to be corrugated with a resulting continuous corrugated web507having corrugations508thereacross in a direction generally perpendicular to the machine direction509being shown. A non-corrugated sheet515is shown being brought into engagement with side516of corrugated sheet507. Typically, the two sheets507,515will be tacked to one another at various points there along, to facilitate the manufacturing process. To accomplish this tacking an adhesive, typically a hot melt, can be used. In some instances sonic welding can be used to effect the tacking.

In some applications, an adhesive bead, hot melt, or sealant strip525is positioned between the two sheets507,515, in a central location. The sealant of the sealant strip is used to ensure a seal, at the location of the fold, in the final product. In the alternative, other sealing techniques such as sonic welds may be useable. The sealant strip525can be applied to continuous sheet506, before it is corrugated on side516. If it is applied to continuous sheet506, before it is corrugated, in general the relevant surface portion of one of the corrugating rollers501,502would preferably have a gap therein to accommodate the sealant bead. In the instance ofFIG. 31, the gap (not viewable) would be in roller502. An advantage to this approach would be that the sealant bead will follow the corrugations508in the corrugated material. As a result, the sealant will be more appropriately located inside of the folds or creases, after processing. This means that a relatively secure closed fold will result, with less sealant used, than would typically be required for an approach in which sealant is first applied to the non-corrugated sheet, for example as shown optionally at525a, before the non-corrugated sheet and the corrugated sheet are brought together.

In a step (shown at indentation station530) a deformation (or indentation or darting) pin arrangement, in this instance comprising a wheel531, is directed into the convex side of each corrugation508on side507aof corrugated sheet507. At this location, an upper form540for supporting (outside support) of each corrugation during the indentation process is provided. Support to the webs507and515underneath, is provided by rollers541,542.

In the machine direction, media web next proceeds to a pressing/folding station550, at which sides resulting from the initial indentation process are folded over toward one another, to form the four crease fold shown inFIG. 15. At pressing/folding station550, a press is used (to cause a center folded strip section570), which will make a press strip that is at least 1 mm wide, typically 4 mm to 40 mm wide in the resulting media construction571. The pressing station550can comprise a wheel572, with a cross-section generally analogous to that shown for wheel185,FIGS. 23 and 24, except dimensioned in width to cause a press width as indicated above. At cutting station580, the media571is shown slit down strip570. This will result in two extensions581,582of media583, each of which has an end respectively terminating in folds, for each convex flute (relative to the flat sheet) with ends similar to end or fold arrangement118,FIG. 15.

Of course, folded flutes could be made at an edge (for example one or more of edges595,596), instead of along a center portion of the corrugated media, using a similar approach. In this latter instance, no final step of slitting would necessarily be required, unless trimming was considered preferable to remove excess sealant or media.

In some instances, it may be possible to apply the initial indentation pressure asymmetrically to the corrugation, i.e., not directed against an apex to cause a symmetrical fold.

In general, when it is desired to apply a mid-web folding process (to fold corrugated media that is already secured to non-corrugated media), by an initial indentation or darting pin projection against an exposed convex surface of an individual corrugation and toward a non-corrugated media, an outer support approach (analogous toFIG. 28) will be preferred. This is because it would be difficult to provide corrugation support along an inner surface, between the flat sheet and the corrugated sheet, especially along a center portion of a corrugated sheet/flat sheet combination.

B. An Approach to Supported Indentation with an Outer Support;FIGS. 32-40.

Outside support to a corrugation, during an indentation step, can be provided in practice, by a variety of arrangements. InFIG. 32-40, a support arrangement is shown, which utilizes a rotating roller or wheel. InFIG. 32, the roller or wheel is indicated generally at reference numeral650, in perspective view. InFIG. 33, the roller wheel650is shown in side elevational view. InFIG. 34, a portion of roller or wheel650is shown in enlarged view.FIG. 35is a fragmented, schematic, cross-section of roller or wheel650, taken generally along line35-35,FIG. 34. InFIG. 36a schematic view showing an indentation step, using an indentation pin arrangement652is shown. InFIG. 36a, an enlarged portion ofFIG. 36is depicted. InFIGS. 37 and 38, a darting or indentation pin projection is shown. InFIGS. 39-40, an internal cam component is shown.

Referring first toFIG. 32, wheel650is an outside support wheel655for corrugations, during an indentation step of a corrugation folding process. In addition, wheel650includes a projectable/retractable indentation pin arrangement652, not viewable inFIG. 32, to provide for an initial indentation step into a corrugation, during a portion of a folding process. This will be discussed below, in connection with the descriptions ofFIGS. 36 and 36a.

Still referring toFIG. 32, in general the wheel650includes an outer, annular, corrugation engagement surface657, depicted enlarged inFIG. 34. Referring toFIG. 34, the outer corrugation engagement surface657comprises a plurality of alternating ridges658and troughs659sized and configured, to engage an outside surface of a corrugated material. Preferably the ridges658and troughs659are configured to define a regular, curved, wave pattern of straight ridges and troughs, corresponding to the corrugation pattern of the media to be folded, except surface657is positioned around the outside of a wheel650, and thus the corrugations658and troughs659have a slight radius to their extension, not present in the corrugated media when the media is flattened out, as shown inFIG. 31.

Referring toFIG. 32, a bottom661of each trough659includes, in a central portion662thereof, a slot663. The slot663is sized and positioned so that an indentation pin arrangement652, not shown inFIG. 32, can selectively be projected through the slot663, in a direction away from a center axis664of the wheel650(or toward media), to cause an indentation in a selected, supported, corrugation during use. (Also the indentation pin arrangement652can be retracted through slot663toward axis664.)

Still referring toFIG. 32, for the particular embodiment shown, the wheel650is mounted on a rotation bearing665. Preferably the wheel650is mounted such that its rotation will be driven by the corrugated media in use. That is, preferably wheel650is not driven during use, except through engagement with the corrugated media to be folded,FIG. 31.

Still referring toFIG. 32, preferably each ridge658and trough659has an end extension668,669at opposite ends of each slot663of sufficient length, to support the corrugation to be deformed at opposite ends of the slot663, during an indentation process. Preferably the length of each extension668,669is at least 6 mm., and typically at least 12 mm. Typically, each slot663will have a length of at least 6 mm., typically at least 12 mm.; and a width of at least 0.5 mm., typically at least 0.7 mm.

In general, the indentation pin arrangement652will include a pin projection/retraction mechanism constructed and arranged to selectively drive or project an indentation or darting pin arrangements through one of slots663against or into an engaged corrugation to be folded, and to selectively retract an indentation pin arrangement when appropriate. This process can be understood, by consideration of the embodiment depicted inFIGS. 36-40.

Referring toFIG. 36, wheel650is shown schematically, in engagement with corrugated media672. In particular, corrugation673is shown supported by trough674of wheel650; see fragmentary enlargementFIG. 36A. Trough674is a particular one of the troughs659and thus includes a slot corresponding to slot663,FIG. 32, in a central portion thereof.

Referring toFIG. 36A, indentation pin arrangement677is shown driven through slot678in a radially outward direction from surface657, and axis664(FIG. 36), into supported corrugation673. As a result, an indentation corresponding to the indentation shown inFIG. 9, in cross-section, is initiated. (It is noted than inFIGS. 9 and 36A, the indentation is shown to be sufficiently long (or deep) to cause the indent679to connect the non-corrugated sheet680. While this is preferred, it is not required in all applications.)

The indentation pin arrangement652, including indentation pin677, is preferably arranged such that projection of the pin677outwardly through slot663,FIG. 36A, is: (a) at its maximum extent of projection at indentation formation position681; i.e., when the pin677is approximately orthogonal to a plane defined by sheet680or as generally defined by troughs682,683on opposite sides of the corrugation673; and (b) so that the pin677is completely retracted out of engagement with the corrugation673when the media is not supported, for example at a rotation angle A (FIG. 36) of no more than 2 times (2×) the pitch in the upstream direction, preferably no more than 1 time (1×) the pitch in the upstream direction. In this context, reference to the “upstream direction”, is meant to a direction from which the web684is fed into the roller650. In the instance ofFIG. 36, the web generally moves in the direction of arrow685. Thus, the upstream side is indicated at686and the downstream side is indicated at687, for the web684. The rotation angle A would be defined as an angle extending clockwise from the center line or indentation formation position681. It is noted that for the arrangement shown inFIG. 36, during operation roller650would rotate counterclockwise, i.e. in the general direction of arrow688. Of course the process could be configured for a reverse rotation and machine direction.

It is generally preferred that the pin arrangement652(FIG. 36A) be under projection movement radially outwardly when it engages the apex of an engaged corrugation plane. This is facilitated by relatively small angle A, since a small angle A helps to provide that the pin is actually being forced radially outwardly from axis664, toward and into engagement with the corrugation673, while the corrugation673is supported. This is shown at locations681and681a, inFIG. 36A.

A variety of arrangements can be used to project and retract the indentation pin677. A particular pin projection/retraction arrangement690is depicted inFIGS. 35-40. It uses a plurality of spring loaded pins677, one associated with each slot663. Referring toFIGS. 37 and 38a pin677is shown in its entirety. The pin677includes a projection portion692, which is configured to pass through slot674with tip693directed toward a corrugation, in use. The projection portion692(FIG. 37) includes beveled ends694,695, for a preferred indentation or deformation. Edge696(FIG. 38) can be rounded or beveled, to facilitate indentation without damage to the media.

The tip693is mounted on projection support697, in extension outward from base698. The base698extends between end portions699,700, with each end699,700including a spring receiving trough701therein.

Referring toFIG. 35, a schematic depiction, an individual pin677is shown mounted by first and second circular springs705,706, to be biased in the direction of arrow707within wheel650. As a result, each pin677will rotate with wheel650around bearing665,FIG. 32, in line with (and in coordination with) its associated slot663.

In order to project selected pins677outwardly through slots663, at the appropriate time, the wheel650is mounted to rotate around a stationary, circular cam711,FIG. 35. By the term “stationary” in this context, it is meant that the cam711does not rotate with wheel650in use.

Referring toFIG. 39, outer annular surface712of cam711, includes a portion712which extends (counterclockwise inFIG. 39) between points713and714of circular, stationary, cam711and is appropriately recessed, relative to the wheel650, such that pins677passing there over, are completely retracted. On the other hand, surface portion716in extension counterclockwise between points717and718operates as a cam surface which, when engaged by surface703of each pin677, will force the pin677to project outwardly through slot663, an appropriate extent to cause desired indentation, usually an extent of projection on the order of 50%-100% of the flute height.

Referring toFIG. 39, movement of the pin677(FIG. 36) from a most retracted position to a most projecting position, occurs the pin engages cam ramp720. The cam ramp720is preferably configured to cause an amount of projection of an associated pin outwardly of at least 50%-100% of the flute height over a preferred rotation angle (angle A) as previously described for36. The reason for this is that it causes a substantial projection effect of the pin, against an associated corrugation in a web, during indenting or darting while the corrugation is supported.

Cam ramp721allows for pin retraction.

It is noted that in the schemation ofFIG. 35, the slot663behind regions722of wheel650, into which the base698of pin677will move, during projection, is not viewable. Also, typically springs705,706are continuous and all pins677are mounted on the same pair of springs705,706to be biased against shelves723in wheel650until cam ramp720(FIG. 39) on cam wheel711is reached.

InFIG. 36a smooth roller725, for back up support to pressure exerted n web684by roller650, is shown.

C. An Approach to Supported Indentation within an Inner Support;FIGS. 41-45.

Attention is now directed toFIGS. 41-45, in which an arrangement for providing inside support to a corrugation, during an indentation process, is shown. Referring toFIG. 41, an inside support730is depicted. Inside support730, generally comprises a rotatable roller or wheel731(or receiver roller or wheel), mounted to rotate around axis731a, on a bearing, not shown. The wheel731has an outer annular surface732configured to provide support to the inside of a corrugation, during an indentation process.

Attention is directed to the side elevational view of wheel731shown inFIG. 42. Surface732can be viewed to comprise a series of troughs734, configured to receive media troughs (or inverted ridges) on opposite sides of a corrugation ridge to be indented. Between each pair of troughs734is provided an indentation support736which preferably comprises opposite, radially outwardly projecting side projections737,738and a recessed center739.

A portion of wheel731is depicted in enlarged view, inFIG. 43. The term “recessed” when used in connection with defining center739, is meant to indicate that a bottom739aof the recessed center739is preferably recessed in the direction of, but not necessarily as far as, bottoms734aof the troughs734.

In the embodiment ofFIG. 43, each center739is recessed the same amount of the troughs734. Typically and preferably each recessed center739has a bottom739awhich, in the cross-section shown inFIG. 43, has a radius about the same as the media thickness plus 0.5× the indention pin thickness.

In general, the surface definition of troughs734and sides737,738is selected to correspond with corrugated media to be supported, during an indentation process. Partially recessed center739is generally sized to receive a projecting portion of an indentation pin arrangement, and a corresponding inverted or indented tip of corrugation media, during an indentation process. An example of this is shown inFIGS. 44 and 45.

Of course the recess center739should be sized to allow for room of the thickness of the media (twice) and the thickness of the indenting pin, during an indentation or deformation process. In this manner, the media will not likely be torn or substantially damaged, during the inside support deformation or indentation process.

In general, wheel731,FIG. 44, would be mounted on a bearing, in a typical process, to be rotated or driven by the corrugated media740as opposed to being independently driven. This will help ensure that the engaged and supported corrugations in the media are centrally positioned. InFIG. 44, the direction of movement of the media740is indicated at arrow741, and the direction of rotation of wheel731by arrow742.

Referring toFIG. 45, web740is shown being indented at752, with inside support provided by roller731. The web direction is indicated at arrow741. The direction of indentation is shown at arrows754.

Of course the indentation pin used with an inside support analogous to inside support730, may be positioned on a wheel analogous to wheel650,FIG. 32, if desired. When this is the case, as shown inFIG. 46, the process would be an encapsulation process for the corrugated media750, to be indented.

In the process ofFIG. 31, midweb darting was involved. For a midweb darting process, generally the indentation could be caused by an arrangement analogous to the wheel650,FIG. 32. That is, with outside support and an underneath support roller that does not include corrugated support structure.

In some systems, it may be desirable to cause indentations at an edge of a web. InFIG. 47, an extension of web760is depicted. Web760has a center801and opposite edges802,803. The web750generally comprises a corrugated sheet810attached to a non-corrugated sheet811. A corrugation process along the center801can be conducted as shown inFIG. 36. A corrugation process along either one of edges802,803, can be also conducted with a process analogous to that shown inFIG. 36, without inside support, as long as the indentation is directed against a ridge of the corrugated media810, in the direction toward the non-corrugated media811. Sealant could be prepositioned at along the edge, between the corrugated and non-corrugated media sheets810,811, to facilitate the process. Of course sonic welding could alternatively to used, in some systems. InFIG. 47, indentation at edge802is shown.

In some instances, it may be desirable to cause the indentation to be driven against a corrugation in an opposite direction from the non-corrugated media. An approach to this is shown inFIG. 48. In particular, inFIG. 48, a web corrugated media850secured to non-corrugated media851is shown. Along edge855, the non-corrugated media856is shown folded away from surface860of the corrugated media. This exposes surface860to potential engagement for corrugation. An encapsulated process such as shown inFIG. 46, except with the indentation and outside support roller861engaging surface862, and the receiver (or inside support) roller865engaging surface866, can then be operated to cause indenting of each of the ridges870in the direction of arrow880. After the process of darting or indenting, the non-corrugated media856can then be folded back into engagement with the corrugated media850along this region. With such an approach it may be desirable to have sealant provided on the corrugated sheet before indentation.

In general, as long as an appropriately flexible media is used for the non-corrugated media851, this approach to darting can be conducted. It will be important to ensure that any tacking of the corrugated media to the non-corrugated media take place at a location sufficiently spaced from the edge at which indentation is to occur to allow for the folds872. Typically, a distance for spacing of such tacking of at least 12 mm from the edge will be sufficient.

From the above techniques, an approach to creating corrugated media which has been darted at both ends can be understood. For example, the approach ofFIG. 32can be used to create a dart fold in each of the upwardly directed ridges of the media. An approach in accord withFIG. 48can be used to create a dart or fold in each of the downwardly directed ridges in the same media. This can be used to create a media then which has each of the inlet flutes each folded closed at the downstream edge; and, each of the outlet flutes folded closed at the upstream edge.

D. Alternatives to Rollers

The particular folding arrangements shown, especially indentation arrangements, are depicted utilizing preferred roller configurations. Of course, alternatives can be used. For example, continuous belts can be configured to provide the support, if desired; and, they can be provided with appropriate slots therein, for indentation pin arrangements to project therethrough. However, the roller configurations depicted, which would typically use rollers on the order of about 150 mm to 300 mm in diameter for the indentation roller (FIG. 32) and about 150 mm to 300 mm in diameter for the receiver roller (FIG. 41), are convenient to manufacture and use.

For any of the processes ofFIGS. 32,46,47and48, a follow-up step of folding media points900,901,FIG. 36aover, typically toward one another, to create the fold ofFIG. 15would be required. This can be conducted with roller572,FIG. 31. The roller572would preferably be as described above.

IV. Some General Observations and Principles

In general, the techniques previously described can be used to provide for preferred fluted filter media constructions. In this context, the term “fluted filter media construction” is meant to refer to a filter construction which includes the media, whether the construction is the media itself or the media provided in the form of an overall serviceable filter element or cartridge, for example cartridges as shown inFIGS. 26 and 27.

The fluted filter media construction preferably comprises a corrugated sheet of filter media having a curved wave pattern of corrugations, preferably a regular curved wave pattern of straight corrugations as defined. The corrugations are such that a set of them define individuals flutes each having an end closure defined by regular fold arrangement in corresponding ones of the set of corrugations. The regular fold arrangement of each corrugation includes at least two folds. Typically for the preferred arrangements described, such as shown inFIG. 15, four folds are provided at each corrugation which is folded closed. For these, two of the folds are generally upper, inwardly directed folds and two of the folds are generally lower, outwardly directed folds.

The typical fluted filter media construction will comprise a sheet of corrugated media having individual flutes each closed by a regular fold arrangement, secured to a non-corrugated sheet of filter media. Typically the filter media construction will include such a combination of a corrugated sheet and a non-corrugated sheet configured to provide a filter cartridge having a set of inlet flutes and a set of outlet flutes, the inlet flutes each being closed to passage of unfiltered fluid therethrough, adjacent the outlet face and each outlet flute being closed, to passage of unfiltered fluid therein, adjacent the inlet face. The term “adjacent” in this context, is meant to refer to a closure that occurs within a distance 20% of the total length of the flute of the most adjacent face. Preferably the closure is within 10% of the length of the flute, of the most adjacent face. Preferably the closure of at least one of the sets of inlet flute and outlet flutes is by the regular fold pattern. In some instances both are closed by the regular fold pattern. When a corrugation or flute end is not closed by a fold, it may be closed by a barrier such as a sealant barrier, or in some other manner. Thus, in some instances a filter cartridge will contain a set of flutes folded closed at one face, and another set of flutes closed by a sealant barrier at another face.

In various filter media constructions, the corrugated sheet and the non-corrugated sheet can be jointly coiled to form a coiled media construction. The coiled media construction may be circular, or may be obround, for example race track shape. In other arrangements, the media would be used in the form of a stack of strips.

In a typical arrangement, the regular fold arrangement would include some sealant herein, to facilitate and maintain closure.

Also according to the present disclosure a process for manufacturing a filter media construction including a sheet of fluted (typically corrugated) filter media having curved wave pattern of corrugations is provided. The process generally includes steps of: (1) deforming a portion of a flute or corrugation to define at least one foldable tip; and (2) folding the at least one foldable tip over, to fold the flute or corrugation closed. Typically, two foldable tips in each corrugation are generated, and are folded over, preferably toward one another.

Preferably the process is conducted on a sheet of corrugated media having a curved wave pattern of corrugations. In many preferred applications, the sheet of corrugated filter media is secured to a sheet of non-corrugated media, to form a continuous web, prior to the step of indenting and folding.

The process may be conducted as a mid-web deformation and folding process, with follow-up slitting. It also may be conducted along a web edge. When conducted along an edge, it can be conducted in a direction toward the uncorrugated media, or, by folding the non-corrugated media out of the way, it can be conducted in a direction away from the non-corrugated media. Of course the process can be conducted on corrugated media that is not secured to non-corrugated media.

The deformation process can be conducted without support, or with outside support or inside support (or both) provided to a corrugation at a location longitudinally adjacent the location or deformation. By the term “longitudinally adjacent” in this context, it is meant that the support occurs in the same location as the deformation, except moved out of the way of the deformation pin arrangement which causes the deformation.

The deformation (typically a step of indenting) can be conducted with an indenting wheel, with a step of folding comprising pressing with a folding wheel. The indenting wheel may comprise a wheel having an outer corrugated surface, to provide for outside corrugation support, with at least one, and typically a plurality, of spaced indentation pins. The indentation pins may be mounted with a projection/retraction arrangement that allows the pins to be projected outwardly from the indenting wheel when indentation is to be conducted, and to be retracted out of the way, when desired.

In a typical process, the corrugated sheet or web would be formed by passing a non-corrugated sheet into the bite between corrugation rollers. In some processes sealant may be provided on the corrugated sheet prior to deformation, by providing the sealant on the web when it is passed into the corrugating rollers, to form the corrugated sheet. This can be advantageous for reasons previously discussed.

It will be understood that the techniques or principles and examples provided, can be provided and used in a variety of specific manners, to accomplish the desired results. The drawings and descriptions are intended to be exemplary only.