US3627623A

US3627623A - Cellular wall structure and method of making same

Info

Publication number: US3627623A
Application number: US802412A
Authority: US
Inventors: Martin L Downs
Original assignee: Hammermill Paper Co
Current assignee: Hammermill Paper Co
Priority date: 1969-02-26
Filing date: 1969-02-26
Publication date: 1971-12-14
Anticipated expiration: 1988-12-14

Abstract

Cored cellular members are made from sheets or webs of paper, paperboard, corrugated board, etc. with cross walls which include portions integrally attached to spaced, opposed facing walls. The integral attachment of the cross walls to the facing walls results in a high-strength connection preventing separation of the cores from the facing walls. The cellular structures may be formed by methods which convert the sheets at high speeds and in a continuous manner.

Description

United States Patent Martin 1.. Downs Appleton, Wis.

Feb. 26, 1969 Dec. 14, 1971 l-lammermill Paper Company lnventor Appl. No. Filed Patented Assignee CELLULAR WALL STRUCTURE AND METHOD OF MAKING SAME 10 Claims, 7 Drawing Figs.

U.S.Cl 161/69, 161/99,161/l00.l61/102,161/104, 161/105, 161/106, 161/107, 161/139, 161/160, 161/161,

Int. Cl 1332b 3/04, B321) 3/20, B32b 5/18 Field of Search 156/156,

197, 204, 209, 202, 210, 474, 512, 548; 29/191.4, 455 LM;52/615; 161/68, 69,127,129,131,l35, 137, 99,139, 160, 250,102, 104, 105,106, 107

[5 6] References Cited UNITED STATES PATENTS 2,426,058 8/1947 Scogland 156/148 X 3,191,724 6/1965 De Ridder 52/615X 3,264,153 8/1966 Rodman et a1 156/79 3,294,387 12/1966 Chavannes 161/127 X 3,346,438 10/1967 Chavannes 156/210 Primary Examiner-John T. Goolkasian Assistant Examiner-Henry F. Epstein Attorney-Luedelta, Fitch, Even and Tabin ABSTRACT: Cored cellular members are made from sheets or webs of paper, paperboard, corrugated board, etc. with cross walls which include portions integrally attached to spaced, opposed facing walls. The integral attachment of the cross walls to the facing walls results in a high-strength connection preventing separation of the cores from the facing walls. The cellular structures may be formed by methods which convert the sheets at high speeds and in a continuous manner.

PATENTED 0501mm 3627'.6 23

SHEET 1 [IF 2 FIG.|

INVENTOR 88 MARTIN L. DOWNS ATTYS.

PATENTEIJ DEB I 41971 SHEET 2 OF 2 INVENTOR ATTYS.

CELLULAR WALL STRUCTURE AND METHOD OF G SAW This invention relates to a cored or cellular structural member having opposed parallel facing walls which are spaced by and joined to interior cross walls resulting in the formation of hollow cells within the interior of the structural member. This invention also relates to a method of making such cored structural members.

Cored structural elements have been used in many fields, for example, as building walls, panels, pallets, door constructions, etc. Partition walls in buildings are cored structures when made with opposed parallel sheets of plywood separated by and secured to opposite sides of wooden studs which are spaced from each other and serve to define cells within the wall. Another cored structural member is a lightweight and inexpensive door made with opposed parallel plywood sheets between which are inserted spaced cores or headers which are glued to the plywood sheets and serve to define hollow cells within the door. There are also some cored structural members used as disposable pallets having opposed facing sheets of paperboard glued on opposite sides of internal cores of corrugated board or wound paper tubes.

The present invention is directed to the forming of cored structural members from thin, lightweight sheets or webs of paper, paperboard or corrugated board, although thin metal or plastic sheets might be used, and overcoming problems which have restricted the use of such cored members. One limiting factor to an expanded use of corrugated board, paperboard or other thin materials as a cored building wall or highstrength uses has been the lack of sufficient strength or rigidity in the final fabricated structure. For instance, present cored structural members are susceptible to failure with separation of the exterior walls from the core cross walls due to the overstressing at the glue lines between the cross walls and exterior walls. Another problem with many cored members involves the expense of cutting, positioning, aligning and fastening of the various cross walls to the exterior walls as this usually involves a number of slow speed and manual operations.

Accordingly, an object of the invention is to provide improved cored structural members made of corrugated board, paperboard or other thin materials.

Other objects and advantages of the invention will become apparent when taken in connection with the accompanying drawings in which:

FIG. 3 is a diagrammatic view of another embodiment of the invention; W 7w 7 V 7 M FIGS. 4, 5 and 6 are diagrammatic illustrations of a method of forming a cored structural member of FlGl and FIG. 7 is an end, fragmentary, cross-sectional view of a nother embodiment of the invention. 7

Generally, as shown in the drawings for purposes of illustration, the invention is embodied in a cored, i.e., cellular, structural member 11 (FIG. 1) and a method of making such structural members in a continuous manner by converting sheets or webs of material such as paper, paperboard, corrugated board, thin metal or plastic. As will be explained in greater detail, the present invention involves the manufacture of structural members with paper or paperboard converting equipment which can be operated at high speeds with a minimum of manual labor whereby structural members can be produced at a lower cost than hand assembled processes of the prior art. Also, the invention is directed to providing such structural members with increased strength, and this is achieved by transferring and distributing forces to cross walls 13 (FIG. 2) from opposite, outer facing

walls

14 and 15 at large interior areas of the cross walls rather than, as in the prior art, across narrow glue lines located at the inner planes of the outer facing walls. To this end, the cross walls 13 may be formed from and integrally attached to the

face walls

14 and 15, as in the embodiment of the invention illustrated in FIG. 1, or the cross walls may include a tuck wall 17 formed from the facing sheets and extending inwardly along and fastened to the transversely extending walls of preformed cores 19, as in the embodiment of the invention illustrated in FIG. 3. By use of tuck walls 17, the facing sheets may be secured to and about substantially the entire circumferential surfaces of the cores to provide wide and large areas of interconnection for force transmission and distribution. This is in contrast to having narrow, glue line connections between the cores and the sidewalls in the prior art at which stresses become concentrated.

Referring now in detail to the several cored members and the methods of making the same, the structural member 11 illustrated in FIG. 1 may be produced by paper converting equipment of the type used to handle relatively wide and continuously traveling paper webs moving at relatively high speeds. For example, a pair of webs 21 and 23 (FIG. 2) of paperboard are stripped from large supply rolls (not shown) and are fed downwardly to a forming station 25 for forming the cellular structure 11. As the

webs

21 and 23 enter the forming station 25, the webs are generally parallel to one another and are spaced on opposite sides of a series of downwardly traveling, block-

shaped spacers

27, 28, 29, 30, 31 and 32 which are generally rectangular in cross section and spaced from each other in the vertical direction at a gap between horizontally disposed adjacent sides. The spacers 27-32 may be fastened at the inner ends thereof to a downwardly moving, endless carrier (not shown) and may have expandable and collapsible outer walls which are moved by either mechanically or pneumatically operated means. A collapsing of the walls inwardly after formation of the cellular structure will facilitate removal of the spacer from the cell.

With the sheets 21 moving downwardly and disposed against the vertical sidewalls 33 of the upper one of the spacers 27, a pair of forming plungers or

blades

35 and 37 move laterally from positions spaced outwardly of the

webs

21 and 23 toward each other to engage the outer sides of the respective webs generally at the location of the gap between the

spacers

27 and 28. The right fonning blade 35 moves to engage the web 23 and forces the web 23 to travel transversely across the horizontal lower face 26 of the spacer 27 into engagement with the opposite web 21 and then forces this opposite web 21 to move horizontally outwardly. As the web 21 moves outwardly from the spacer 27, it encloses and enrobes the fold being formed from the other web 23. A small guide roller 39 is disposed adjacent the lower, left-hand comer of the spacer 27 to assure that the web continues traveling down and close to the spacer. When the right-hand forming blade 35 reaches the end of its leftward travel, it has formed an outwardly extending fold or flap 43 which is four plies thick. At this time, the blade 35 may be withdrawn from the fold.

In a similar manner, the left-hand forming blade 37 moves rightwardly to engage first the left-hand web 21 and moves beneath the path of the right-hand former blade 35 and generally parallel to the upper face of the adjacent spacer 28 until in position to force the right web 23 horizontally and outwardly to the right to fold about and enrobe the fold formed in the left-hand web 21. During formation of the flap 43, a small guide roller 40 holds a portion of the web 23 against the right vertical side of the spacer 28. After forming a four-ply flap 43, the left-hand forming blade 37 is retracted from the fold in this flap and the guide roller 28 is also retracted to an inoperative position.

The flaps 43 are folded upwardly by means such as rollers 47 as the

webs

21 and 23 and

spacers

27 and 28 continue to move downward and carry the flaps 43 downward. It is preferred to adhere the flap 43 to the vertically disposed portions of the web disposed along the vertical sidewalls 33 of the spacer. The outer sides of the

webs

21 and 23 may be wetted with an adhesive from

glue rolls

49 and 50 so that the flaps 43 may be adhered to vertical portions of the respective webs when pressed thereagainst by pressure rolls 51. On the other hand, the outer sides of the webs may be precoated with a heat activable adhesive for securing the flaps 43 under heat and pressure from rotatable heated pressure rolls 51 disposed beneath the rollers 47. Alternatively, the outer sides of the

webs

21 and 23 may be precoated with a heat sealable material such as a polyethylene coating for heat sealing the flaps 43 in vertical positions under heat and pressure from the rolls 5 1.

The preferred length of the flaps 43 is generally coextensive with the vertical walls 33 of the spacers so that outer facing walls are substantially continuous with only slight grooves 52 indicating the end of one flap 43 and the beginning; of the next flap 43. Thus, the outer vertical sides of the structural member have a five-ply thickness for each of the longitudinal sidewalls 14 and as the sidewalls leave the sealing rollers 51. it is preferred that the flaps 43 be covered by suitable

additional cover sheets

53 and 55 which are stripped from

supply rolls

57 and 59 and adhered to the outer plies of the flaps to cover the same and the grooves 52 between the adjacent ends of the flaps. After adherence of the

cover sheets

53 and 55 to the flaps 43, the spacers are removed such as by collapsing the

sidewalls

26 and 33 inwardly to reduce the cross-sectional dimensions of the spacers relative to the dimensions of the surrounding core walls and then retracting spacers in a direction parallel to the length of the hollow cell.

From the above-described method, it will be seen that the cored structural member 11 has four-ply cross walls 13 which are integrally attached to the flaps 43 and the portions of the

webs

21 and 23 forming the

longitudinal sidewalls

14 and 15 of the structural member. Thus, stresses applied to the structural member 11 are directly transferred and distributed between the sidewalls and the cross walls and need not be transferred through nor concentrated at narrow glue lines as in prior art structures. As the structural member 11 was formed in a continuous manner from several webs of paperboard, the usual costly steps of prior art methods involving alignment and placing of cores on sheets and gluing them manually between opposite facing walls have been eliminated.

When the structural member of FIG. 1 is formed of thin flexible paperlike material, the structural member may be collapsed to reduce its thickness and thereby its bulk so that a greater number of structural members can be stored in a given volume. Specifically, the

face walls

14 and 15 may be shifted in opposite directions to incline the cross walls 13 to provide a parallelogram shaped cross section for the cores. Where the cored structural member 11 is to be used as a wall for or in a building, the sidewalls will be shifted in the reverse directions until the cross walls 13 are again disposed at the normal rectangular cross section. For a typical building wall, the cross-sectional area of the cell will be slightly greater than that of a nominal 2X4 stud. Thus, a wooden 2X4 stud may be inserted into the appropriate ones of cells and at the desired spacings for holding the facing

walls

14 and 15 against lateral shifting and for fastening the structural member 1 l in position in the building.

For use in building construction, the

webs

21 and 23 may be made of or with a water resistant or waterproof material. For example, the

webs

21 and 23 may be made of a paper based material coated with a polyethylene coating. Such a waterproof coating permits the hollow cells to be filled with a wet aggregate, plastic foam or other material capable of hardening, in situ, in the cells to provide rigid supports and/or compression members for the structural member 11. Also, the sheets may be treated or impregnated with a suitable organic fireproofing material to increase the fire rating for the structural member.

To make the structural member 11 more rigid, reinforcing means such as continuous reinforcing bands or strips (not shown) of metal may be fastened to the opposite faces 14 and 15 to lock the same against shifting or pivoting relative to one ream another. it will be appreciated that various longitudinal apertures may be provided in the sheets to receive utilities, electrical wiring or other elements. Also, the cross walls may be perforated or scored to provide knockouts which will serve as longitudinally aligned apertures to receive such utility lines.

The structural member 11 may also be made by precreasing each of the

webs

21 and 23 at the location of each of the fold lines defining the flaps, cross walls and vertical walls. Then the folds are erected and positioned by suitably collapsing the web to form the cross walls 13 and flaps 43 prior to the folding and securing of the flaps 43 in place.

In accordance with another embodiment of the invention, a cellular structural member 71 (FIG. 3) is formed with opposite, parallel facing

walls

73 and 75 attached to the internal prefonned cores 19 by the tuck walls 17. In this instance, the preformed cores 19 are formed of convolutely wound sheets of polyethylene coated paper wound to provide a rectangularly shaped cross-sectional hollow cell in the interior thereof. In this instance, the preformed core 19 has three

plies

81, 82 and 83 bonded to each other to define a relatively rigid core. These preformed cores 19 may be formed to quite close tolerances and thus provide a structural member with good dimensional accuracy.

When making the structural member 71, the preformed cores 19 are carried by a suitable conveyor along a path of travel such as to the right as viewed in H6. 3.

Sheets

86 and 87 extend across the upper and lower faces respectively of the preformed cores. Forming means including a pair of reciprocal blades and 88 force portions of the

sheets

86 and 87 inwardly into gaps between transversely extending core walls 77 and thereby form folded tuck walls 17. The forming of the tuck walls 17 may be assisted by precreasing the

sheets

86 and 87 at longitudinally spaced locations to provide the fold lines for the tuck walls 17. Preferably, the tuck walls 17 extend inwardly to abut each other at fold lines 89 positioned generally centrally of the transverse core walls 77.

The inner sides of the

sheets

86 and 87 are secured, such as by an adhesive, to both the core transverse core walls 77 and to horizontally disposed, core outer walls 90. in this illustrated structural element 71, substantially the entire peripheral area of each of the cores 17 is engaged by and adhered to the sheets forming the facing walls for the structural member. This wide area adhesion permits stresses to transfer between the outer walls and the core walls and distributes forces applied to the cores over large areas thereby resulting in less force per unit area tending to break the adhesion between the cores and the facing walls. To cover grooves 91 at the location of the tuck walls 17, cover webs or

sheets

93 and 95 are stripped from the supply rolls and suitably bonded by an adhesive to each other to the opposite sides of the

respective sheets

86 and 87.

The preformed convolutely wound cores 19 may be made in the manner of tubular forms for receiving concrete so that concrete, cement or other wet and hardenable material may be poured therein and hardened, in situ. If concrete is poured in the hollow cores 19, the structural member 71 functions both as a form as well as the finished structural member. lnorgarric additives may be added to the paper or other flame proofing agents may be added to the cores, the facing

sheets

85 and 86 and cover

sheets

93 and 95 so that the concrete wall structure 71 is provided with an improved fire rating.

A further kind of cored structural element 97 is illustrated in FIG. 7 and is formed with preformed cores 100 attached along their transverse sides 101 to tuck

walls

103 and 104. The tuck walls 103 are formed from an outer facing sheet and the other tuck walls 104 are formed from an opposite facing sheet 106. In this instance, the

respective tuck walls

103 and 104 extend and are bonded to an entire face of the core. That is, the

tuck walls

103 and 104 extend the full distance between the

face sheets

105 and 106 rather than meeting one another in a generally central plane as in the embodiment of FIG. 3.

In the structural element 97, the tuck walls 103 from the sheet 105 extend the full length of a transverse core wall and alternate with the tuck walls 104 from the sheet 106 rather than having tuck walls formed from both sheets and inserted to meet each other as in structural member '71 illustrated in FIG. 3. To achieve good strength, the

tuck walls

103 and 1% are secured as by a suitable adhesive along and to the entire area of the transverse walls 101 of the core elements Likewise, the facing

sheets

105 and 106 are adhered to the outer sides 108 of the core elements 100. Also, the plies of the folded

tuck walls

103 and 104 are adhered at an interface 107 between the plies. If it is decided to cover the grooves existing at the location of the

tuck walls

103 and 104, a pair of outer cover sheets 109 may be disposed on and adhered to the outer sides of the

cover sheets

105 and 106.

The preferred method of making the structural member 97 will be described in connection with the illustrations in FIGS. 4, 5 and 6. Referring to FIG. 4, pairs of the core elements 100 are placed on and adhered to the facing sheet 105 with a relatively large spacing 110 between the pairs of core elements, the spacing 110 being slightly greater than twice the dimension of an outer wall 108 for the core elements. The cores 100 are adhered at sides 101 to the facing sheet 105. The latter is engaged by an upsetting or by a folding mechanism. For instance, a folding mechanism operates a folding blade 112 (P16. 5 which, as viewed in this figure, engages the underside of the sheet 105 at points in planes located between the closely spaced walls 108 of each pair of core elements. As the folding blades 112 move upwardly and form the tuck walls 103, the blades cause the core elements 100 to pivot through approximately 90 turning the short sides 108 of the cores 100 from a generally vertical position to a substantially horizontal position, as viewed in these figures. After the tuck wall 103 is formed, the folding blade 112 retracts, the plies of the tuck wall are abutted at the interface 107 and are adhered together by suitable adhesive. it will be appreciated that the cores 100 will upset from the position illustrated in FIG. 4 to that illustrated in FIG. 6 upon application of an upward force causing the cores 100 to pivot and that it is not necessary to form a fold by the folding blade 112, particularly if the sheet 105 is already precreased to form a fold.

With the tuck walls 103 formed and securing the core elements at alternating positions, the other facing sheet 109 is brought over the outer, now unsecured walls 108 of the core elements and suitable tucking blades (FIG. 6) form tuck walls 104 as the tucking blades move into the spaces left between the adjacent pairs of core elements 100. Preferably, the tuck walls 104 are also adhered to transverse walls of the core elements 100 and along the common interface between the plies of the tuck walls 104 to provide a relatively solid and rigid cored structural element. Then if desired, cover sheets 109 may be disposed over the outer sides of sheets and adhered thereto.

An alternative method of forming the cored structural element 97 would be to form the same generally in the manner hereinbefore described in connection with a structural element 71 of FIG. 3 with exception that

folding blades

85 and 88 would have a longer travel or stroke and form a tuck wall extending substantially the full length of the transverse core wall. Also, the folding blades would be inserted alternatively rather than simultaneously to form a tuck wall at each spacing between the cores.

From the foregoing, it will be seen that cored structural elements may be made from a number of relatively thin and flexible materials with cross walls defining cores or spaces within the interior of the cored structural member providing rigidity and strength to the cored structural member. The cross or tuck wmls may be integrally formed from the sheets forming the face walls or may serve to provide large additional interior areas of contact with preformed core elements. In either event, there is a considerable area of contact between the core elements and the facing walls and particularly within the interior of the core element so that stress concentrations are applied more uniformly throughout the product than is the case with prior art structural elements in which only an outer side or face of the preformed core element was attached to facing sheets at glue lines which tended to concentrate stresses resulting in ultimate failure in some instances. As seen from the foregoing, cored structural elements may be made with relatively high-speed paper converting machinery thereby eliminating the usual assembly and alignment of large numbers of preformed cores.

While a preferred embodiment has been shown and described, it will be understood that there is no intent to limit the invention by such disclosure, but rather, it is intended to cover all modifications and alternate constructions falling within the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. A cellular structure comprising means including a first sheet of cellulosic material defining a first face wall for said cellular structure, means including a second sheet of cellulosic material disposed parallel to and spaced from said first sheet and defining a second face wall, fold lines in each of said first and second sheets, cross walls formed from each of said sheets and integrally attached to said face walls at said fold lines, said cross walls extending between said face walls and dividing the space between said face walls into a series of hollow cells, each of said cross walls being a multi-ply wall with the plies thereof in face to face engagement.

2. A cellular structure in accordance with claim 1 in which the cross walls are formed with at least four plies, two plies of which are formed from each of said first and second sheets and in which said cross walls are disposed substantially normal to the facing walls.

3. A cellular structure in accordance with claim 1 in which hollow preformed tubular members are fastened along first sides thereof to said facing walls and along other sides thereof to said cross walls.

4. A cellular structure in accordance with claim 3 in which said hollow preformed tubular members are formed of multiply sheets, said tubular members having first and second pairs of parallel sidewalls.

5. A cellular structure in accordance with claim 4 in which said cross walls of said sheets extend inwardly and meet substantially centrally in the space between said sheets and each are fastened to at least one of said parallel sidewalls of said hollow preformed members.

6. A cellular structure in accordance with claim 4 in which said cross walls extend substantially across the space between said sheets and in which cross walls formed from one sheet alternate with the cross walls formed from the other sheet, each of said cross walls abutting and secured to a pair of adjacent hollow tubular members.

7. A cored structural member comprising a first sheet of cellulosic material defining a first face wall for said cored structural member, a second sheet of cellulosic material defining a second face wall disposed in a plane generally parallel to and spaced from said first face wall, a plurality of hollow cores inserted into the space between said first and second facing walls and having faces abutted against and secured to the respective first and second face walls, fold lines in each of said first and second sheets and tuck walls formed from and integrally attached to at least one of said facing walls at said fold lines and extending inwardly from the plane thereof, said tuck walls abutted against and fastened to sides of said hollow cores.

8. A cored structural member in accordance with claim 7 in which said hollow cores are preformed and have opposed pairs of parallel sidewalls, and in which said tuck walls are formed in both of said face sheets and extend inwardly toward one another along the core sidewalls extending transversely of the face sheets.

9. A cored structural member formed of a first and second web of cellulosic material, said cored structural member including spaced parallel facing walls each comprised of a series of flaps each having multiple plies of said first and second webs, and fold lines in said first and second webs and cross in which folded plies of one web are enrobed by the other web at a flap in one facing wall and in which the folded plies of the other web are enrobed with said one web at a flap in the other facing wall.

Claims

2. A cellular structure in accordance with claim 1 in which the cross walls are formed with at least four plieS, two plies of which are formed from each of said first and second sheets and in which said cross walls are disposed substantially normal to the facing walls.
3. A cellular structure in accordance with claim 1 in which hollow preformed tubular members are fastened along first sides thereof to said facing walls and along other sides thereof to said cross walls.
4. A cellular structure in accordance with claim 3 in which said hollow preformed tubular members are formed of multi-ply sheets, said tubular members having first and second pairs of parallel sidewalls.
5. A cellular structure in accordance with claim 4 in which said cross walls of said sheets extend inwardly and meet substantially centrally in the space between said sheets and each are fastened to at least one of said parallel sidewalls of said hollow preformed members.
6. A cellular structure in accordance with claim 4 in which said cross walls extend substantially across the space between said sheets and in which cross walls formed from one sheet alternate with the cross walls formed from the other sheet, each of said cross walls abutting and secured to a pair of adjacent hollow tubular members.
7. A cored structural member comprising a first sheet of cellulosic material defining a first face wall for said cored structural member, a second sheet of cellulosic material defining a second face wall disposed in a plane generally parallel to and spaced from said first face wall, a plurality of hollow cores inserted into the space between said first and second facing walls and having faces abutted against and secured to the respective first and second face walls, fold lines in each of said first and second sheets and tuck walls formed from and integrally attached to at least one of said facing walls at said fold lines and extending inwardly from the plane thereof, said tuck walls abutted against and fastened to sides of said hollow cores.
8. A cored structural member in accordance with claim 7 in which said hollow cores are preformed and have opposed pairs of parallel sidewalls, and in which said tuck walls are formed in both of said face sheets and extend inwardly toward one another along the core sidewalls extending transversely of the face sheets.
9. A cored structural member formed of a first and second web of cellulosic material, said cored structural member including spaced parallel facing walls each comprised of a series of flaps each having multiple plies of said first and second webs, and fold lines in said first and second webs and cross walls having at least four plies which are integrally connected to and formed from said first and second webs, said cross walls joined to said flaps at said fold lines and extending transversely between said facing walls and dividing the spaces therebetween into cells.
10. A cored structural member in accordance with claim 9 in which folded plies of one web are enrobed by the other web at a flap in one facing wall and in which the folded plies of the other web are enrobed with said one web at a flap in the other facing wall.