US3510383A - Method and apparatus of corrugating - Google Patents

Description

May 5, I970 J. 1'. YCVANOVICH METHOD AND APPARATUS OF CORRUGATING Filed Nov. 10

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May 5, 1970 J. 'r. Y OVANOVIC ZH METHOD AND APPARATUS OF CORRUGATING 6 Sheets-Sheet 4 Filed Nov. 10, 1965 l ww MK M

May 5, 1970 J. 'r. YOVANOVICH 3,510,333

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May 5, 1970 J. 'r. YOVANOVICH METHOD AND APPARATUS OF CORRUGATING 6 Sheets-Sheet 6 Filed Nov. 10 1965 3,510,383 METHOD AND APPARATUS OF CORRUGATING Joseph T. Yovanovich, Rosemont, Pa., assignor to National Tube and Reel Corporation, Belleville, N.J., a corporation of New Jersey Filed Nov. 10, 1965, Ser. No. 507,191 Int. 'Cl. B31f 1/00, 1/20 US. Cl. 156462 8 Claims ABSTRACT OF THE DISCLOSURE This invention relates generally to corrugating methods and apparatus.

It is an important object of the present invention to provide a highly improved apparatus for and method of corrugating relatively inextensible sheet material without rupture or other damage to the sheet material.

It is still another object of the present invention to provide a unique method and apparatus for producing corrugated sheet material wherein the corrugations are of generally rectangular, or other nonround cross-sectional configuration, in order to obtain increased strength of the corrugated sheet and greater adhesive holding power, all without damage to the corrugated sheet.

It is still a further object of the present invention to provide a unique method of and apparatus for producing diagonal corrugations in an elongate sheet or web, and wherein plural diagonally corrugated sheets may be secured together to produce a stronger structure than heretofore possible with the same materials.

The invention further contemplates the provision of corrugating apparatus which is relatively simple in construction, durable and reliable throughout a long useful life, and which can be economically manufactured, maintained and operated for inexpensively producing corrugated sheet.

Other objects of the present invention will become apparent upon reading the following specification and referring to the accompanying drawings, which form a material part of this disclosure.

The invention accordingly consists in the features of construction, combinations and arrangements of parts and method steps, which will be exemplified in the following description and of which the scope will be indicated by the appended claims.

In the drawings:

FIG. 1 is a diagrammatic elevational view showing a conveyor line for producing corrugated sheet in the final form of cloth boards;

FIG. 2 is a top plan view, somewhat enlarged, illustrating a section of the production line of FIG. 1;

FIG. 3 is an enlarged side elevational view showing the corrugating apparatus of the present invention, partly broken for convenience in illustration;

FIG. 4 is a sectional elevational view taken generally along the line 44 of FIG. 3, enlarged to illustrate greater detail;

FIG. 5 is a sectional elevational view taken generally along the line 5-5 of FIG. 3, also enlarged;

FIG. 6 is a partial sectional elevational view taken generally along the line 6-6 of FIG. 3;

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3,510,383 Patented May 5, 1970 FIG. 7 is a partial sectional View taken generally along the line 7-7 of FIG. 6;

FIG. 8 is a top view of the apparatus of FIG. 3, as taken along the line 8-8 of FIG. 3;

FIG. 9 is a horizontal sectional view taken generally along the line 99 of FIG. 3;

FIG. 10 is a horizontal sectional view taken generally along the line 1010 of FIG. 3;

FIG. 11 is a sectional view taken generally along the line 1111 of FIG. 8;

FIG. 12 is a partial sectional view taken generally along the line 1212 of FIG. 11;

FIG. 13 is a partial plan view of the apparatus shown in FIG. 11; and

FIG. 14 is a diagrammatic representation taken generally along the line 1414 of FIG. 8.

Referring now more particularly to the drawings, and specifically to FIG. 1 thereof, there is illustrated therein a production line for the manufacture of cloth-board reels in accordance with the teachings of the instant invention. In particular, the production line includes corrugating apparatus, generally designated 20, from which issue upper and lower corrugated sheets or webs 21 and 22, and an intermediate, generally flat sheet or web 23. The intermediate web 23 may pass through an adhesive applicator 24 which applies adhesive to opposite faces of the intermediate sheet.

The corrugated sheets 21 and 22, with the web 23 sandwiched between the corrugated sheets, pass together through a laminating station 25 where the corrugated sheets are moved into engagement with respective adhesive-coated surfaces of intermediate sheet 23. Issuing from the laminating station 25 is a three-ply web or sheet 26, constituted of the upper and lower corrugated sheets 21 and 22, and intermediate web 23 sandwiched between the corrugated sheets.

The sandwich structure, or built-up sheet 26 then passes to a wrapping station 27, where a covering web or sheet 28 is passed longitudinally with the sandwich structure 26 and through a wrapping or folding former 29 to wrap the web 28 about the sandwich structure. The wrapper web 28 may be supplied from a reel 29a over a roll 30 for movement thence longitudinally with the sandwich structure 26 through the former 29. The folding of wrapper web 28 about the sandwich structure 26 is shown in greater detail in FIG. 2. It will there be seen that opposite longitudinal margins 31 and 32 of the wrapper web 28 are folded into overlapping engagement, and may be adhesively secured together, as by passage through a pressure securing station 33.

From the securing station 33, the wrapped sandwich structure 35 may pass to a severance or cutoff station 36, from which may issue predetermined lengths 37 of the board construction.

The corrugating apparatus 20 is best seen in FIGS. 3-5, as including a base or bottom support 40 extending longitudinally of the production line. At the forward or inlet end of the corrugating apparatus 20, there are a pair of laterally spaced, upstanding support walls or standards 41 and 42 fixed on the base 40 by any suitable means. At the rear or outlet end of the apparatus 20, upstanding from the base 40 are an additional pair of support walls or standards 43 and 44, see FIG. 4. The front and rear support walls 41 and 43 are in alignment with each other longitudinally of the corrugating apparatus, while the front and rear support walls or standards 42 and 44 are in alignment with each other longitudinally of the corrugating apparatus.

An upper corrugating conveyor, generally designated 46 extends longitudinally of the production line from a forward or inlet end between the support walls 41 and 42 to a rear or outlet end between the support walls 43 and 44. The upper corrugating conveyor 46 is spaced over the base 40, and a lower corrugating conveyor 47 is interposed between the base and upper corrugating conveyor. Thus, the lower corrugating conveyor extends longitudinally of the production line from a forward or inlet end between the front support walls 41 and 42 to a rear or outlet end between the rear support walls 43 and 44. The upper and lower corrugating conveyors 46 and 47 may extend generally horizontally in a longitudinal direction, and may be essentially similar in construction.

Intermediate the upper and lower corrugating conveyors 46 and 47 is a generally horizontal, longitudinally extending web conveyor 48. The web conveyor 48 extends from a forward or inlet end between the front support walls 41 and 42 and a rear or outlet end between the rear support walls 43 and 44.

Associated with each of the upper and lower corrugating conveyors 46 and 47, and intermediate web conveyor 48, at the inlet ends thereof, is a web or sheet guide for feeding a flexible sheet to the respective conveyor. In particular, an upper sheet guide 49 is arranged forward of and adjacent to the inlet end of corrugating conveyor 46, while an intermediate sheet guide 50 is arranged forward of and adjacent to the inlet end of web conveyor 48, and a lower sheet guide 51 is arranged adjacent to and forward of the inlet end of lower corrugating conveyor 47.

The upper corrugating conveyor 46 includes a pair of upper and lower endless bands or belts 54 and 55 of longitudinally elongate configuration, one above the other.

The upper endless band or belt 54 is trained about a pair of forward or front wheels 56 and 57, respectively carried by supports 41 and 42, and a pair of rear wheels 58 and 59, respectively carried by rear supports 43 and 44. The front wheels 56 and 57 are spaced horizontally forward from the rear wheels 58 and 59, so that the belt 54 may be considered as having an upper or outer run 60 and lower or inner run 61.

The lower endless band or belt 55 of the upper corrugating conveyor 46 is similarly trained about a pair of forward wheels 62 and 63 respectively carried by the front support walls 41 and 42, and a pair of rear wheels 64 and 65 respectively carried by the rear support walls 43 and 44, and spaced horizontally rearward from the front wheels. The lower endless band or conveyor 55 of the upper corrugating conveyor 46 may then be considered as having a lower or outer run 66, and an upper or inner run 67. As best seen in FIG. 3, the inner runs 61 and 67 of the endless bands 54 and 55 extend longitudinally of the production line in facing relation with each other.

It will be observed, see FIG. 3, that the front wheels 56 and 62 are directly over each other, while the front wheels 57 and 63 are directly over each other. Further, the front wheels 56 and 62 are spaced forward of the front wheels 57 and 63, although all of the front wheels are rotatable about generally horizontal axes normal to the longitudinal direction of conveyor movement. Thus, the band 54 in passing about the front wheels 56 and 57 extends diagonally of the longitudinal direction of conveyor movement, approximately 45 degrees thereto. Similarly, the band 55, when passing about the front wheels 62 and 63 extends diagonally, approximately 45 degrees, relative to the longitudinal direction of conveyor movement. The rear wheels 58 and 64 on one side of the corrugating conveyor 46 are similarly arranged one over the other, as are the rear wheels 59 and 65 on the other side of the conveyor. Further, the rear wheels 59 and 65 are spaced rearward of the rear wheels 58 and 64, so that the bands 54 and 55, when passing over the rear wheels extend diagonally, approximately 45 degrees, with respect to the longitudinal direction of conveyor movement.

The lower wheels 62, 63, 64 and 65 may be mounted by any suitable means in their respective supporting walls 41, 42, 43 and 44; and if desired, provision may be made for adjustment of the Wheel-journaling means, say horizontally and/ or vertically. The upper wheels 56, 57, 58 and 59 are also suitably carried by their respective supporting walls 41, 42, 43 and 44, and provision is illustrated for vertical adjustment thereof. For example, a journal bearing 70 may rotatably receive the shaft 71 of wheel 56, and may be carried by the wall support 41 in a vertical slot 72 of the wall support. The journal bearing 70 may be carried at the lower end of a depending screw 73 which is connected by a meshing wormand-wheel mechanism 74 to a longitudinally extending rotary shaft 75. The shaft 75 may be rotated by a handwheel 76 for effecting a selected vertical adjustment of conveyor-band Wheel 56.

The shaft 75 is carried by a journal bearing 69 on the wall support 41, and extends rotatably through an additional journal bearing 77 on the support wall 43 adjacent to the rear wheel 58. By similar worm-and-wheel means 78, see FIG. 6, the shaft 75 is connected to a depending screw 79 which carries at its lower end a vertically adjustable journal bearing 80 rotatably supporting the shaft 81 of rear wheel 58. By this means simultaneous vertical adjustment of wheels 56 and 58 is achieved upon rotation of shaft 75, as 'by handwheel 76.

In addition, the upper wheels 57 and 59 on the opposite side of the conveyor 46 may be similarly vertically adjusted. For example, see FIG. 4, the rear wheel 59 may have its shaft 83 rotatably supported in a journal member 84 which is carried at the lower end of a depending screw 85 rotatably carried by support wall 44. The screw 85 may be connected in positive driven relation with the screw 79, as by a chain 86 for simultaneous movement of the screws. Also, the upper front wheel 57 may be similarly mounted for vertical adjustment and connected for simultaneous movement, as by a chain 87 from the depending screw 63. It will now be appreciated that the several wheels 56, 57, 58 and 59, supporting the upper corrugating-conveyor band 54, may be simultaneously vertically adjusted by rotation of the handwheel 76, say to move the inner runs 61 and 67 toward and away from each other. Alignment of the several wheels 56-59 in any selected position of their vertical adjustment may be insured by the provision of forwardly and rearwardly extending constraining members 90 and 91, the former being connected between the journal bearings of wheels 57 and 59, and the latter being connected between the journal bearings of wheels 56 and 58. In addition, the upper wheels 56-59 may be provided with means for horizontal, forward and rearward adjustment, if desired.

The upper band 54 may include a pair of endless chains 93 and 94, the former being trained about the wheels 56 and 58, and in the latter being trained about the Wheels 57 and 59. The chains 93 and 94, and wheels 5659 may be of conventional sprocket-type construction, with the chains passing about the respective wheels on the pitch diameter thereof. Thus, the links of chains 93 and 94 always extend normal to their axes of rotation and maintain a fixed spacing with respect to adjacent links. The chains 93 and 94 may be modified roller-sprocket chains, wherein a sidepiece of each link may be provided with a mounting arm or bracket, as at 95 of chain 93 on the radially outer side thereof. The links of chain 94 are similarly provided, on the radially outer side thereof, with mounting brackets 96. The mounting brackets 95 and 96 are thus disposed generally normal to the radii of curvature of the respective link movement. On each mounting member or bracket 95 there is provided a rotary member or swivel block 97 projecting outward from the respective bracket 95 and connected to the latter by a pivot 98. The connecting pivot pin 98 of each swivel block 97 extends normal to the direction of link movement, and thus along the radius of curvature of link movement. The outer end of each swivel block 97 is generally U shaped, as best seen in FIG. 13, in the manner of a clevis receiving a crosspin 99 extending between its legs.

Similarly, the mounting member or bracket 96 carried by each link of chain 94 is disposed generally normal to the direction of link movement; and, a generally U- shaped or clevis-like swivel block 100 extends normal to and outward from each bracket 96, being connected thereto by a pivot member or pin 101 extending along the radius of curvature of link movement. In addition, a pivot pin 102 may extend between the outer-end legs of each swivel block 100.

In the manner of roller-sprocket chains, the links of chains 93 and 94 maintain a constant spacing, and move along the pitch diameters of their respective sprocket wheels. However, the clevis-type swivel blocks 97 and 100 project radially from the respective chain links beyond the pitch diameters thereof, so that the outer ends of adjacent swivel blocks are swung angularly away from each other upon movement along curved paths, as about sprocket wheels.

Extending laterally between the chains 93 and 94 are a plurality of bars or slats 105, each having its opposite ends connected to swivel blocks of respective chains; Thus, each slat or bar 105 has one end interposed between the legs of a swivel block 97, and connected thereto by its pin 99, while the outer slat end is interposed between the legs of a swivel block 100, and connected thereto by the associated pin 102. Further, the slats 105 extend between the chains 93 and 94 so as to pass about the front wheels 56 and 57 generally parallel to a line connecting the centers of the wheels, and similar relation with respect to the rear wheels 58 and 59.

It will now be appreciated that each slat 105 is connected at each end by a universal connection to one link of the respective adjacent chain 93, 94. Specifically, the pins 99 and 98 of each swivel block 97 are disposed normal to each other to define a universal connection between each slat 105 and the chain 93, while normally disposed pins 101 and 102 define a universal connection between each slat 105 and chain 94. The respective chains are thus movable about their offset wheels, while the slats 105 are swingable relative to the chains to maintain connection therebetween upon continuous movement about the endless paths of the chains. As best seen in FIG. 8, the slots 105 extend diagonally, approximately 45" degrees, to the longitudinal direction of chain movement. Further, as noted hereinbefore, the slats 105 will maintain a substantial parallelism while moving along the upper and lower runs 60 and 61 of the endless band 54, but will assume an increased angular spacing between adjacent slats upon their movement about the curved paths of the sprocket wheels. This variation in angular spacing between slats 105 is best illustrated in FIG. 14.

The lower endless band 55 of upper corrugating conveyor 46 may include chains similar to chains 93 and 94 and be provided with slats 107 connected to the chains in the samemanner as slats 105. Further, as best seen in FIG. 3, the slats 107 of band 55, when on the upper or inner run thereof, move in interdigitating or alternately interposed relation with respect to the slats 105 on the lower or inner run of band 54. While in their interdigitated relation, on the inner runs of bands 54 and 55, the slats 105 and 107 may have no relative movement, being moved at equal velocities toward the outlet end of the corrugating conveyor. However, during movement of slats 105 and 107 into and out of their interdigitated relationship, as at the inlet and outlet ends of the corrugating conveyor, there is relative movement between the slats of a particular nature.

Referring to FIG. 14, it will appear that there is relative movement between adjacent slats 105 to reduce the angular spacing therebetween as the slats move from the inlet wheels 56 and57 to the inner run 61. This change in relative angular spacing between the slats is re versed, or increased, upon movement of the slats from the inner run 61 to the outlet wheels 58 and 59. Similarly, the angular spacing between slats 107 decreases as the slats move from the inlet wheels 62, 63 to the inner run 67, where the spacing remains constant, and thence increases upon movement from the inner run to the outlet wheels 64 and 65. It is in the region of decreasing angular spacing between adjacent slats that a sheet or web 108 to be corrugated enters between the bands 54 and 55. While the sheet 108 may be of any desired material, it has been found entirely practical to employ paper, cardboard, or the like, which materials are readily subject to rupture. However, in the instant invention the slats 105 engage with longitudinally spaced locations on one face of sheet 108 and effect simultaneous movement of the spaced locations beyond the centerline or plane of the sheet toward the nonengaged surface while moving the spaced locations longitudinally of the sheet toward each other. This occurs simultaneously on the opposite face of sheet 108 by the action of slats 107. Thus, by this action of the slats in engaging spaced locations of the sheet 108 and moving these locations longitudinally of the sheet toward each other, while simultaneously depressing the sheet beyond its centerline or median plane, it will be understood that the sheet is alternately bent or folded in opposite directions to define corrugations, and that the bending or folding is accomplished with little or no relative movement of the slats with respect to the sheet at the points of engagement. Thus, forces tending to rupture or otherwise damage the sheet are eliminated or minimized.

The guide 49 for sheet 108 may be mounted by any suitable means at the inlet end of corrugating conveyor 46, as by a bracket 109 fixed to the support wall 41 and rotatably receiving the depending vertical shaft 110 of an upstanding member 111. The guide 49 may include a pair of laterally spaced side walls 112 and 113, which may be of generally arcuate configuration, and a plurality of generally parallel rods 114 may extend between and maintain the side members 112 in their fixed relationship. A shaft 115 may extend from the sidepiece 112 into the upstanding mounting member 111, such that the guide 49 is adjustable both about the vertical axis of rod 110 and horizontal axis of shaft 115. The arcuate arrangement of crossrods 114 maintains the sheet 108 in an arcuate configuration for increased rigidity thereof to prevent buckling, and assures entry of the sheet between the bands 54 and 55 in an undefaced condition.

The lower corrugating conveyor 47 may be essentially the same as the upper corrugating conveyor 46, including a pair of upper and lower endless bands or belts and 121, the former carrying outwardly projecting slats 122, and the latter carrying outwardly projecting slats 123. The belts 120 and 121 may be mounted in essentially the same manner as the belts 54 and 55, suitable provision for adjustment being made, if desired. Further, the interrelationship between the slats 122 and 123 may be substantially identical to the interrelationship between slats 105 and 107. However, in the illustrated embodiment it is preferred that the slats 122 and 123 extend diagonally in the opposite direction with respect to the longitudinal dimension as the slats 105 and 107. Hence, the corrugations formed by-the upper corrugating conveyor 46 extend in one direction diagonally of the longitudinal, while the corrugations formed by the lower corrugating conveyor 47 extend in another diagonal direction, as seen in FIG. 2.

Also, the sheet guide 51 may be essentially identical to the sheet guide 49, but is advantageously adjusted for feeding a sheet at an opposite angle of inclination, corper and lower corrugating conveyors 46 and 47.. The intermediate conveyor 48 may include a pair of upper and lower entry wheels 125 and 126 mounted for rotation about generally horizontal axes, and a pair of upper and lower exit wheels 127 and 128, also mounted for rotation about horizontal axes. Trained about the upper entry wheel 125 and upper exit wheel 127 may be an endless flexible band or belt 129, and an additional endless flexible band or belt 130 may be trained about the lower entry wheel 126 and lower exit wheel 128. The belts 129 and 130 include inner runs in facing engagement with each other and are movable to convey a web 131 between the inner runs for discharge from between the exit rolls 127 and 128.

The sheet feed guide 50 may be substantially identical to the guides 49 and 51, but is arranged in alignment with the longitudinal direction of feeding, as the intermediate sheet 131 is not diagonally corrugated, or corrugated at all.

In order to drive the corrugating conveyors 46 and 47, and intermediate web conveyor 48, there may be provided a horizontal drive shaft 135 connected by bevel gears 136 and 137 to a shaft 138. The shaft 138 may be connected in driving relation by a chain 139 with the shaft of exit roll 128 of the intermediate conveyor. A spur gear 140 is carried on the shaft 138 for meshing engagement with a spur gear 141, the latter being carried by a shaft 142 and connected by a drive chain 143 to the shaft of upper exit roller 127 of the intermediate conveyor. The lower band 55 of the upper corrugating conveyor is driven by a spur gear 145 on the shaft 146 of wheel 65; and, a spur gear 147 in meshing engagement with gear 145 is carried by the shaft of wheel 59.

The wheels 64 and 58 are similarly positively driven, as are the rear or discharge-end wheels of the lower corrugating conveyor 47, to insure properly synchronized motion of all parts.

From the foregoing, it is seen that the present invention provides a unique and highly advantageous method of corrugating and apparatus therefor which fully ac complish their intended objects and are well adapted to meet practical conditions of manufacture and use.

What is claimed is:

1. A corrugating apparatus comprising a pair of endless bands each trained about inlet and outlet wheels and having inner and outer runs with the inner runs of respective bands being in longitudinally extending facing relation, motive means for moving said bands about their endless paths at equal linear velocities, a plurality of rigid slats carried by each of said bands extending obliquely thereacross and movable therewith into interdigitating relaiton with the slats of the other band upon passage about said inlet wheels to said inner runs and out of said interdigitating relation upon passage from said inner runs about said outlet wheels, and universal mounting means mounting each slat on its respective band at a generally constant angle relative thereto, the slats of each band moving between increased angular spacing along said wheels and decreased angular spacing along said runs, whereby a sheet to be corrugated entering between said inlet wheels is engaged on opposite surfaces by slats of respective bands moving toward decreased angular spacing to gather the sheet material and effect corrugation with minimum relative movement between slats and sheet.

2. A corrugating apparatus according to claim 1, said bands each comprising chain means having a pitch diameter equal to the pitch diameter of the respective inlet wheel, said slats projecting from respective chains outwardly beyond the pitch diameters thereof at substantially constant angle thereto, whereby said slats are radially separated upon movement along said inlet wheels.

3. A corrugating apparatus according to claim 1, said slats having their projecting portions of generally rectangular cross-sectional configuration to define corrugations of generally rectangular formation.

4. A corrugating apparatus according to claim 1, said bands each comprising a pair of endless members located in longitudinally offset relation along the path of sheet movement, and said slats extending between corresponding locations on said endless members, whereby the angle of offset of said endless members defines the obliqu disposition of said slats.

5. A corrguating apparatus according to claim 4, said chain means each comprising a pair of laterally spaced chains extending about respective inlet and outlet wheels, said slats extending between said pair of chains for movement therewith at a substantially constant angle thereto.

6. A corrugating apparatus according to claim 5, the chains of each band and associated wheels being offset longitudinally of the direction of sheet movement to determine the oblique disposition of said slats.

7. A corrugating apparatus comprising a pair of endless bands each trained about inlet and outlet wheels and having inner and outer runs with the inner runs of respective bands being in longitudinally extending facing relation, motive means for moving said bands about their endless paths at equal linear velocities, a plurality of slats carried by each of said bands extending transversely there across and movable therewith into interdigitating relation with the slats of the other band upon passage about said inlet wheels to said inner runs and out of said interdigitating relation upon passage from said inner runs about said outlet wheels, the slats of each band moving between increased angular spacing along said wheels and decreased angular spacing along said runs, for corrugating a sheet entering between said inlet wheels by engaging the sheet on opposite surfaces with slats of respective bands moving toward decreased angular spacing to effect corrugation with minimum relative movement between slats and sheet, a web conveyor for conveying a web into adhesive engagement with one side of a corrugated sheet emerging from between said pair of bands, a second pair of endless bands each trained about respective inlet and outlet wheels and having inner and outer runs with the inner runs of respective bands in longitudinally extending facing relation, a plurality of slats carried by each of said second pair of bands extending transversely there across and movable therewith into interdigitating relation with the slats of the other of said second pair of bands upon passage about respective inlet wheels to the inner runs of said second pair of bands and out of said interdigitating relation upon passage from the inner runs of said second pair of bands about respective outlet wheels, the slats of each second pair of bands moving between increased angular spacing along respective wheels and decreased angular spacing along respective runs, for corrugating a second sheet passing between said second pair of bands, and means for adhesively engaging a corrugated sheet emerging from between said second pair of bands with a web from said web conveyor on the opposite side of said web as the corrugated sheet from said first pair of bands.

8. A corrugating apparatus according to claim 7, the slats of said first pair of bands extending in one direction diagonally with respective to the direction of sheet movement between said bands, and the slats of said second pair of bands extending diagonally in the other direction with respect to the direction of sheet movement between said bands, whereby corrguated sheets emerging from between said first and second pairs of bands have their corrugations extending diagonally in opposite directions.

References Cited UNITED STATES PATENTS 1,650,050 11/1927 Smith 93-1 1,931,365 10/1933 Watson 156591XR (Other references on following page) References Cited UNITED STATES PATENTS Palmer 156592 XR Kappler 156-591 XR Burrill 156-471 Andreoli et a1. 156206 Wells et a1. 161137 Granozio 156-471 Hecker 156471 10 JOHN T. GOOLKASIAN, Primary Examiner D. I. FRITSCH, Assistant Examiner US. Cl. X.R.

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