US3542356A - Web folding apparatus and method - Google Patents

Description

United States Patent [72] Inventors James A. Murphy, Toronto, Ontario,

Canada, Charles A. Lee Knoxville, Tennessee; Eduards Spravniks, Weston, Ontario, Canada 21 Appl. No. 737,034

[22] Filed June 14,1968

Continuation-impart of Ser. No. 569,671,

Aug. 2, 1966, now Pat. No. 3,472,504.

[45] Patented Nov. 24, 1970 [73] Assignee International Paper Company New York, New York a corporation of New York. by mesne assignments [54] WEB FOLDING APPARATUS AND METHOD 16 Claims, 19 Drawing Figs.

[52] US. Cl..... 270/40 [51] Int. Cl. B65h 45/22 [50] Field of Search 270/40, 41, 86

[56] References Cited UNITED STATES PATENTS 2,642,279 6/1953 Teall 270/40 3,199,861 8/1965 Presnell et al. 270/40 3,291,479 12/1966 Greiner et al..... 270/40 3,330,553 7/1967 Couzens et al 270/40 Primary Examiner-Eugene R. Capozio Assistant Examiner-Paul V. Williams Attorney-Robert Graham Mc Clenahan ABSTRACT: An apparatus and method for interfolding a succession of webs into a continuously moving stack of webs. In an illustrative embodiment, there is provided a plurality of folding devices which are effective to interfold successive pairs of tissue webs by turning over an edge portion of one of the webs substantially simultaneously with an edge portion of a previously laid down web. At least one of the edge portions being interfolded by each device is maintained in a substantially flattened condition during the turning over thereof so that its cross section forms a substantially straight line The folding devices are ofidentical construction and include guide elements having spiral-shaped surfaces which are similar in several respects to the surfaces ofa propeller blade. These surfaces direct the edge portions of the webs along gradually curving paths during the interfolding operation Patented Nov. 24, 1970 3,542,356

Sheet L of 5 l WEB FOLDING APPARATUS AND METHOD CROSS REFERENCES TO RELATED APPLICATIONS BACKGROUND OF THE INVENTION Although the present invention is useful wherever a stack or package of interfolded webs is required. one particularly advantageous use is in the facial tissue field. As more fully described in U.S. Pat. No. 3,285,599 granted Nov. I5, 1966, to Perry 0. Ph'earson, James A. Murphy and Cecil H. Watkins, a commercial consumer-size box of tissue illustratively may contain 360 separate sheets of tissue in short lengths cut from a long stack. In facial tissue operations of this type, the stack is built up by bringing together 360separate tissue webs from 360 separate supply rolls of tissue. As the webs are assembled in the stack, they are interfolded by a series of folding devices to produce one or more longitudinal folds on each web. The assembled stack is cut off into convenient lengths which are then packaged in wrappers or paperboard boxes of a size suitable for use by the consumer.

a Heretofore, difficulties have been encountered in the interfolding of a succession of webs into a stack of webs. For example, in many ofthe machines previously employed for this purpose the individual folding devices included boards, rods, etc., having comparatively sharp folding edges. These edges tended to form sharpbends in the webs with the result that unwanted creases and wrinkles appeared which occasionally rendered the wrinkled portions of-the stack unsuitable for use. Another difficulty has arisen because of the need, in many prior machines, for making different types of folding devices depending upon whether it was desired to produce a left-hand fold or a right-hand fold in a given web. The prior folding devices were often of unnecessarily complicated construction which resulted in a further increase in the already high cost of the machine.

SUMMARY One general object of this invention therefore, is to provide a new and improved apparatus and method for interfolding a succession of webs.

More specifically, it is an object of this invention to provide such apparatus and method which avoids the unnecessary formation ofcreases and wrinkles in the webs being folded.

Another object of this invention is to provide an apparatus and method of the character indicated in which individual folding devices need not be of different construction from one device to another.

Still another object of this invention is to provide a novel method for interfolding a succession of webs in stacked relation.

A further object of the invention is to provide web folding apparatus utilizing comparatively simple mechanical elements which is economical to manufacture and thoroughly reliable in operation.

In one illustrative embodiment of this invention, there is provided a machine and method for automatically interfolding a succession of webs into a continuously moving stack. The webs are directed in pairs from suitable supply rolls to a plurality of folding devices which are disposed at spaced folding locations along the path of the stack. The folding devices include a first folding device for receiving a first pair of webs to be interfolded into the stack, and a second folding device for receiving a second pair of webs to be interfolded into the stack. The webs in each pair are led to the corresponding folding device in contact with each other and in substantially unfolded condition, and the webs in the first pair proceed along the path of the stack from the first folding device to the second folding device. Each of the folding devices is provided with guide elements having spiral-shaped surfaces for turning over the edge portions ofthe webs and placing them so that the edge portion of one web lies between the edge portions of another web. The thus interfolded stack is then cut to appropriate lengths for packagingand delivery to the purchaser.

In accordance with one feature of several advantageous embodiments of the invention, at least one of the edge portions of the webs being interfolded by each folding device is maintained in a substantially flattened condition during the turning over thereof so that its cross section forms a substantially straight line. With this arrangement, the handling of the webs is maintained at a minimum, and the incidence of unwanted creases or wrinkles is substantially reduced.

In accordance with another feature of the invention, in certain preferred embodiments. the spiral-shaped surfaces on the guide elements of the folding devices direct the edge portions of each of the received webs along gradually curving paths, thereby further reducing the possibility of producing unwanted creases or wrinkles in the webs.

In accordance with still another feature of the invention, in several good arrangements, the second folding device is effective to turn over the edge portion of one of the received wet-s substantially simultaneously with the edge portion of a previously laid down web. The arrangement is such that the webs in a given pair are interfolded into a previously laid down pair prior to the completion of the folding of the previous pair. As a result, the handling of the webs is further reduced, and a corresponding reduction is realized in the incidence of unwanted creases and wrinkles.

BRIEF DESCRIPTION OF THE DRAWINGS tures thereof, will be understood more clearly and fully from the following description of a preferred embodiment when read with reference to the accompanying drawings, in which:

FIG. 1 is a top plan view of successive pairs of facial tissue webs as they are interfolded into a stack of webs in accordance with one illustrative embodiment ofthe invention;

FIG. 2 is aside elevational view of the webs shown in FIG. 1, with portions of the folding devices therefor indicated in phantom lines;

FIGS. 3, 4 and 5 are vertical sectional views through the webs respectively taken along the lines 33, 4-4 and 5-5 in FIG. 2;

FIG. 6 is a side elevational view of one portion of a folding device for interfolding the webs in the manner shown in FIGS. 1-5;

FIG. 7 is a side elevational view of another portion of the folding device;

FIG. 8 is a side elevational view of the assembled folding device portions shown in FIGS. 6 and 7, together with certain additional parts;

FIG. 9 is a top plan view ofthe portion ofthe folding device shown in FIG. 6;

FIG. 10 is a top plan view of the portion of the folding device shown in FIG. 7

FIG. 11 is a top plan-view of the assembled folding device portions shown in FIG. 8',

FIGS. 12-18 are vertical sectional views respectively taken along the lines 12-12 to 18-18 of FIG. 8, showing the progressive interfolding of two successive pairs FIG. 19 is a vertical sectional view through the pairs of webs shown in FIGS. 12-18 as the webs emerge from the folding device of FIG. 8.

DESCRIPTION OF A PREFERRED EMBODIMENT f Referring to FIGS. l5 of the drawings, there is shown a succession of facial tissue webs which are being interfolded into a continuously moving stack of webs indicated generally at 25. The webs are led to the stack 25 from a series of supply rolls-(not shown herein but illustrated in the aforementioned U.S. Pat. application Ser. No. 569, 671) which are arranged in 3. pairs above the path of the stack. As the webs are advanced in the stack, they-are interfolded by positioning an edge portion of one web between the edge portions of another web. The assembled and interfoldedstack of webs is advanced along its path by a suitable conveyor mechanism and is cut off into finished lengths which are then packaged in wrappers or paperboard boxes for the consumer.

The webs being interfolded into the stack 25 include a first pair of webs 26 and 27 and a second pair of webs 28 and 29. The webs 26 and 27 in the first pair are received by a first folding device, the location of which along the path of the stack is shown at 30, and the webs 28 and 29 in the second pair are received by a second folding dev'ice located at 31. The webs in each pair are led to the corresponding folding device with the webs in contact with each other and in substantially unfolded condition. In addition to the webs 26 and 27, the first folding device 30 receives a previously laid down pair of webs, one of which is visible at 33. Similarly, in addition to the webs 28 and 29 the second folding device 31 receives the webs 26 and 27 from the first folding device 30.

A plurality of folding devices, such as the devices 30 and 31, are arranged in spaced-apart relationship with each other at a series of folding locations along the path of the stack 25. As will become more fully apparent hereinafter, the folding devices are of identical construction, and one device is provided for each pair of webs to be interfolded into the stack. Each of the devices is effective to interfold the webs by turning over a longitudinal edge portion of one of the received webs substantially simultaneously with an edge portion of a previously laid down web. Thus, as best shown in FIGS. 3-5, the webs 26, 27 and 33 respectively include left and right lon' gitudinal edge portions 26a and 26b, 27a and 27b, and 33a and 33b. The webs 26 and 27 are led to the folding'device 30 with their edge portions 26a and 27b in overlapping contact with each other and with their edge portions 26b and 27a on opposite sides of the device. The web 33 comprises one of a pair of webs which are similarly led to the immediately preceding folding device (not shown). The web 33 is maintained substantially open as it passes through the preceding device with its edge portions 33a and 33b in spaced apart relationship with each other. The edge portions 33a and 33b remain in this relationship as the web moves through the space between the preceding device and the device 30. The device 30 is effective to simultaneously turn over the edge portion 33a of the web 33 and the edge portion 26b of the web 26 so that the edge portion 26b lies beneath the edge portion 33a. During the turning over of these edge portions, each edge portion is directed along a continuously but gradually curving path. in addition, at least the edge portion 33a is held in a substantially flattened condition throughout its passage through the folding devices, so that its cross section forms a substantially straight line. The arrangement is such that the handling of the webs is maintained at a minimum, with the result that unwanted creases or wrinkles in the folded product are substantially reduced.

The edge portion 27a of the web 27 likewise is maintained in a substantially flattened condition during its movement through the folding devices 30 and 31. As the edge portion 27a passes through the device 30, it is raised with respect to the edge portion 27b. The raising of the edge portion 27a continues in the space between the device 30 and the device 31, such that by the time the web 27 reaches the device 31 its edge portions 27a and 27b meet at an acute angle. The device 31 is effective to turn over the edge portion 27a substantially simultaneously with an edge portion'(not shown in FIGS. 3--5) of one ofthe webs in a subsequently laid down pair.

THEFOLDING DEVICES may be supported for movement in a direction opposite to that of the stack 25 (FIG. 2) in a manner more fully disclosed in copending U.S. Pat. application Ser. No. 569,671 referred to heretofore. A sloping rectangular plate All is welded or otherwise suitably affixed to the lower end of the column 37. The plate 40 includes a pair of infeed rollers 41 adjacent the forward or leading end thereof (the left end as viewed in FIG. 8) and a depending flange 42 along one side of the plate. The flange 42 is welded to one of the longitudinal edges of a folding element 43. As best shown in FIGS. 7 and T0, the element 43 comprises a plate which is substantially flat but is twisted adjacent its forward portion to form a gradually curving folding surface 45. The surface 45 is shaped somewhat in the manner of a portion of a propeller blade or screw and is of generally spiral configuration. The rearwardly directed portion of the element 43 forms a flattened channel or slot $6 (FIGS. 13-18) with the adjacent portion ofthe plate 40.

Affixed to the folding element 43 immediately beneath the flange 42 is a channel member 48 (FIGS. I4ill6). The member 48 interconnects the element 43 and a second folding element 50 disposed therebeneath. The element 50 is of generally V-shaped cross section and includes a flat horizontal portion SI and an upstanding portion 52. The portion 52 is bent such that at its forward or leading end it forms an angle of approximately 60 with respect to the horizontal portion 51. At the rearward end, however, the portion 52 is substantially parallel to the portion 51. Intermediate the forward and rearward ends, the portion 52 forms a gradually curving spiralshaped folding surface 54. This surface is somewhat similar to the folding surface 45 on the folding element 43 but is of the opposite sense. That is, whereas the surface 45 is disposed adjacent the right portion of the folding device 30, as seen in the forwardmost sectional view of FIG. 12, and curves inwardly to the left in the progressively rearward views of FIGS. 13 18, the surface 541 is oriented adjacent the left portion of the device in FIG. 12 and curves inwardly to the right in the succeeding FIGS. The surface 54 is positioned at a level beneath the surface 45 adjacent the forward portion of the folding device, but the comparatively steep downward slope of the surface 45 is such that the surfaces are at the same level from about the location of the section line l3-l3 (FIG. 8) to the rearward end of the device.

As best shown in FIGS. 6 and 18, the rearward portion of the folding element 50 includes an upstanding tongue 56. The tongue 56 is formed from a separate piece 57 which is welded at 58 to the element 50. The piece 57 includes two flat sections 60 and 61 which define a horizontal opening 62 therebetween. The tongue 56 extends upwardly from the section 60 and includes a slightly curved folding surface 63 on its inner side which is disposed at an angle of approximately with respect to the horizontal. The section 60 is coplanar with the adjacent portion 52 of the element 50 and is spaced therefrom to define a slot 65. As best shown in FIG. 9, this slot extends at an angle with respect to the longitudinal dimension of the folding device and is spaced a short distance ahead of the tongue 56. The forwardmost portion of the piece 57 is bent outwardly to form a finger 67.

OPERATION The path of the various tissue webs through the folding device 30 may be traced from an examination of FIGS. 12- 19. FIGS. l218 illustrate the pair of webs 26 and 27, which are received by the device 30 directly from the corresponding supply rolls, and also the previously laid-down pair of webs 33 and 34, which are received from the immediately preceding folding device. FIG. 19 illustrates these four webs as they emerge from the device 30.

In the position shown in FIG. 12, the webs 33 and 34, having been previously laid down on the stack 25, are disposed adjacent the lower portion of the folding device 30 with the web 34 completely folded into the stack but with the web 33 still in a comparatively open, unfolded condition. The edge portion 33b of the web 33 is positioned between the two edge portions 34a and 34b ofthe web 34, while the edge portion 33a of the flat plane. The orientation of the supply rolls is such that the inwardly directed edge'portion 26a of the web 26is positioned above and in overlapping relationship with the inwardly directed edge portion 27b of the web 27. The remaining edge portions 26b and 27a, on the other hand, are located externally with respect to the device 30 on opposite sides thereof.

Upon reaching the position shown in FIG. 12, the web 27 remains in its flattened condition, while the interfolding of the web 26 is initiated by the folding surface 45 of the plate element 43. In this FIG 11s well as in FIG. 13, the forward portion of the element 43 has been shown by dash lines. As the web 26 moves through the folding device 30 to the respective positions indicated in FIGS. 13-17, the surface 45 is effective to turn over the edge portion 26b of the web 26 and to position this edge portion beneath the edge portion 26a. The surface 45 directs the edgeportion 26b along a continuously curving path until the portion 26b reaches the turned-over position shown in FIGS. 17-19. In this position the edge portion 26b lies between the edge portions 33a and 33b of the web 33; The change in direction of theedge portion 26b as it moves along its path is sufficiently gradual that the possibility of producing unwanted wrinkles or creases in the edge portion is substantially eliminated. .The arrangement is such that the turning over of the edge portion 26b. takes place entirely during the passage of the web 26 through the folding device 30.

Simultaneously with the turning overof the edge portion 26b of the web 26, the edge portion 33a of the web 33 from the immediately preceding device is turned over by the folding device 30. The turning over of the edge portion 33a is initiated by the immediately preceding device in a manner to be described hereinafter with respect to the edge portion 270. The turning overof the edge portion 33a continues inthe space between the two folding devices until by the time the web 33 enters the device 30 and reaches the position shown in FIG. 12, the portion 33a meets the remaining portion 3312 at an angle which is. slightly less than 55. The portion 33a is received by the folding surface 54 and is progressively folded over the edge portion 26b as the webs continue their movement through the successive positions shown in FIGS. 13, 14 and 15.

As the web 33 approaches the FIG. 16 position, thefinger '67 engages the edge portion 330 immediately adjacent the longitudinal center line of the web. The finger 67 .directs the edge portion 33a into the angularly extending slot 65. This slot is effective to urge the edge portion 33a to the right, as viewed in FIGS. 16 and 17, and thus insure that the edge portion is fully interfolded between the edge portions 26a and 26b of the web 26. At the time the web 33-reaches the position shown in FIG. 18, the interfolding of the web is complete,'and the edge portion 33a is disposed within the horizontal opening 62 between the folding element sections 60 and 61. The remaining edge portion 33b of the web 33 is posed between the edge portions 340 and 34b ofthe web 34.

The edge portions 27a and 27b of the web 27 are maintained in a substantially open condition as this latter web moves through the folding device 30. The edge portion 27a moves around the rollers 41' (FIG. 2) and then traverses substantially the entire length of the folding device without coming in contact therewithIAs the portion 27a reaches the upstanding tongue 56 (FIG. 18), the portion contacts the inwardly facing surface 63 of the tongue and is guided by this surface toward the succeeding folding device. The surface 63 is effective to initiate the turning over of the edge portion 27a, such that at the time the web 27 leaves the device 30 the edge portion 27a meets the edge-portion 2711 at an angle ofapproximately 90. As best shown in FIG. 19, the turning over of the edge portion 27a continues in the space between the device 30 and the succeeding device. The edge portion 27a is received bythe folding surface 54 (FIG; 12) of the succeeding device fective to simultaneously (1) completely turn over an edge portion of one of the webs in the pair, thereby forming, say, a left-hand fold, (2) turn over an edge portionofa web received from the immediately preceding folding device, thus completing a right-hand fold, and (3) initiate the turning over of an edge portion of the other web in the pair, preparatory to the formation of a right-hand fold. A portion of the right-hand fold for this latter web is formed in the space between adjacent folding devices and the fold is completed by the succeeding device. The arrangement is such that there is a total of not more than one folding device for each pair of webs being interfolded by the machine.

It will be apparent from the foregoing description that each of the edge portions being turned over by a given folding device is directed along a continuously curving, spiral-shaped path, no sharp folding edges being employed. In addition, at least one ofthe edge portions, namely, the edge portion 27a, is maintained in a flattened condition throughout its movement through two successive folding devices so that the cross section of the edge portion forms a substantially straight line. With this arrangement, the handling ofthe webs during the interfolding operation is maintained at a minimum, and a substantial reduction is realized in the incidence of unwanted creases and wrinkles.

Each of the folding devices is of identical construction and is fabricated from only three separate pieces of sheet steel or other flat structural material. The devices are of comparatively simple configuration and are economical to manufacture in the large quantities customarily employed in tissue folding machinery.

The terms and expressionswhich have been employed are used as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described, or portions thereof, it being recognized that various modifications are possible within the scope of the invention claimed.

We claim:

1. In a machine for interfolding a succession of webs into a continuously moving stack, in combination, a first folding device positioned along the path of said stack for receiving a first pair of webs, and a second folding device positioned along the path of said stack in spaced relationship with said first folding device for receiving a second pair of webs, said folding devices having guide elements for turning a given edge portion of one of said webs and a given edge portion of another of said webs over said stack so that the last-mentioned edge portion lies between the edge portions of said one web, said guide elements including plate means defining a gradually curving surface for maintaining at least one of said given edge portions in a flattened condition throughout the turning over thereof.

2. In a machine for interfolding a succession of webs into a stack ofwebs, in combination, a first folding device positioned along the path of said stack for receiving a first pair of webs to be interfolded into said stack, and a second folding device positioned along the path of said stack immediately adjacent said first folding device for receiving a second pair of webs to be interfolded into said stack, said folding devices having guide elements for simultaneously turning a given edge portion of one of said webs over said stack so that the last-mentioned edge portion lies between the edge portions of said one web, said guide elements including plate means for maintaining'at least one of said given edge portions in a flattened condition throughout the turning over thereof.

3. In a machine of the character set forth in claim 2, each of said guide elements having a spiral-shaped surface for directing said given edge portions along gradually curving paths during the turning over thereof.

4. In a machine for interfolding a succession of webs into a continuously moving stack, in combination, a first folding device positioned along the path of said stack for receiving a first pair of webs to be interfolded into said stack, and a second folding device positioned along the path of said stack immediately adjacent said first folding device for receiving a second pair of webs to be interfolded into said stack, the webs in each of said pairs being led to the corresponding folding device with the webs unfolded and in contact with each other, said second folding device having guide elements for simultaneously turning a given edge portion of one of said webs and a given edge portion of another of said webs over said stack so that the last-mentioned edge portion lies between the edge portions of said one web, one of said guide elements including means defining a gradually curving surface for maintaining at least one of said given edge portions in a flattened condition throughout the turning over thereof so that its cross section forms a substantially straight line.

5. In a machine for interfolding a succession of webs into a continuously moving stack, in combination, a first folding device positioned along the path of said stack for receiving a first pair of webs to be interfolded into said stack, and a second folding device positioned along the path of said stack immediately adjacent said first folding device for receiving a second pair of webs to be interfolded into said stack, the webs in said first pair being directed from said first folding device to said second folding device, said second folding device having guide elements for turning a given edge portion of one of the webs in said first pair and a given edge portion of one of the webs in said second over said stack so that the last-mentioned edge portion lies between the edge portions of the one web in said first pair, one of said guide elements including means defining a gradually curving folding surface maintaining at least one of said given edge portions in a flattened condition throughout the turning over thereof so that its cross section forms a substantially straight line.

6. in a machine of the character set forth in claim 5, another of the guide elements for said second folding device having a curved folding surface for directing the other of said given edge portions along a curved path during the turning over thereof. 1

7. in a machine of the character set forth in claim 6, the degree of curvature for the folding surface on said one guide element being less than the degree of curvature for the folding surface on the other guide element.

8. In a machine for interfolding a succession of webs into a continuously moving stack, in combination, a plurality of substantially identical folding devices positioned along the path of said stack in spaced-apart relationshipwith each other, said folding devices including a first folding device for receiving a first pair ofwebs to be interfolded into said stack and a second folding device immediately adjacent said first folding device for receiving a second pair of webs to be interfolded into said stack, the webs in each of said pairs being led to the corresponding folding device with the webs unfolded and in contact with each other, the webs in said first pair being directed from said first folding device to said second folding device, said second folding device having guide elements for simultaneously turning a given edge portion of one of the webs in said first pair and a given edge portion of one of the webs in said second pair over said stack so that the last-mentioned edge portion lies between the edge portions of the one web in said first pair, one of said guide elements including plate means for maintaining at least one of said-given edge portions in a flattened condition throughout the turning over thereof so that its cross section forms a substantially straight line.

9. In a machine of thecharacter set forth in claim 8, the guide elements of said second folding device defining an elongated slot extending at an angle with respect to the path of said stack, said second folding device including finger means for directing said one given edge portion into said slot as it moves along said path.

10. In a method for interfolding a succession of webs into a continuously moving stack as the webs move along a feed path the steps of feeding a first pair of webs to a first folding location along said feed path, feeding a second pair of Webs to a second folding location along said feed path, turning a given edge portion of one of said webs and a given edge portion of another of said webs over said stack at said second folding location, inserting the last-mentioned edge portion between the edge portions of said one web at said second folding location, and maintaining at least one of said given edge portions in a flattened condition throughout the turning over thereof so that its cross section forms a substantially straight line,

ii, In a method for interfolding a succession of webs in stacked relation as the webs move along a feed path, the steps of feeding a first pair of webs to a first folding location along said feed path, feeding a second pair of webs to a second ing location along said feed path, directing said ct: webs along said feed path from said first folding location to said second folding location, simultaneously turning a given edge portion of one of said webs and a given edge portion of another of said webs over said stack at said second folding location, inserting the last-mentioned edge portion between the edge portions of said one web at said second folding location, and maintaining at least one of said given edge portions in a flattened condition throughout the turning over thereof so that its cross section forms a substantially straight line.

12. in a method for interfolding a succession of webs in stacked relation as the webs move along a feed path, the steps of feeding a first pair of webs in contact with each other in substantially unfolded condition to a first folding location along said feed path, feeding a second pair of webs in contact with each other in substantially unfolded condition to a second folding location along said reed path, directing said first pair of webs along said feed path from said first folding location to said second folding location, simultaneously turning a given edge portion of one of the ebs in said first pair and a given edge portion of one of the webs in said second pair over said stack at said second folding location, inserting the lastmentioned edge portion between the edge portions of the one web in said first pair at said second folding location, and maintaining at least one of said given edge portions in a flattened condition throughout the turning over thereof so that its cross section forms a substantially straight line.

13. In a machine for interfolding a plurality of webs into a continuously moving stack, each of said webs having a longitu dinal center line and a pair of edge portions which extend in transverse cross section continuously from said center line to the opposite edges of the web, a folding device comprising a pair of guide elements positioned along the path of said stack,

' each of said guide elements having a web-contacting surface which gradually curves inwardly in the direction of movement of said stack toward the longitudinal center thereof, the webcontacting surface on one of said guide elements curving inwardly from adjacent one side of said stack and the web con-' tacting surface on the other guide element curving inwardly from adjacent the opposite side of said stack, and means for feeding a pair of said webs through said folding device with the webs in overlapping relationship with each other at the time they reach said folding device, said feeding means directing a given edge portion of one of the webs in said pair along the web-contacting surface of said one guide element and directing a given edge portion of the other web in said pair along the web-contacting surface of said other guide element, said given edge portions being directed by said feeding means along the inwardly curving paths defined by said web-contacting surfaces to gradually fold said given edge portions over said stack.

14. In a machine of the character set forth in claim 13, the web-contacting surface of-said one guide element maintaining the given edge portion therefor in a flattened condition during the turning over thereof so that its cross section forms a substantially straight line.

which the degree of curvature of the web-contacting surface of said one guide element is less than the degree of curvature of the web-contacting surface of the other guide element.

Images