Creasing cellulosic fiber strips
United States Patent Hollier, Jr.  
 14 1 Apr.&#39;29, 1975 CREASING CELLULOSIC FIBER STRIPS Joseph H. Hollier. Jr.. Peurcy. Ark.  
 Assignee: Sutco. lnc.. Hot Springs. Ark.  
 Filed: May ll. I973 Appl. No.: 359.218  
 Inventor:  
 U.S. Cl 93/84 R: 93/1 R: 93/20 1m. Cl 1531b 1/36 Field of Search 93/84 R. 1 R. 1 F. 21)  
 References Cited UNITED STATES PATENTS 11/1936 Milletl 93/84 R X 2.270.721 1/1942 Weslphul 93/84 R X 2.385.646 9/1945 Poppc 11 93/20 X 2.929.303 3/1961) Armstrong 93/114 R 3.164.111) 1/1965 Wilkic L2! :11 93/84 R 3.165.311) 1/1965 Peterson M 93/84 R Primary Examiner-Roy Lake Aazs&#39;l&#39;xumr kirurm&#39;rrcr-James F. Cnun Armrncy, Agent. or Firm-Gc0rgc F. Hclfrich 1571 ABSTRACT A longitudinal gmuve is formed in a surface 01 an advancing cellulosic fiber strip such as wallbonrd tape.&#34; and the strip is caused to bend along the length of the groove and fold upon itself.  
 1 Claim. 2 Drawing Figures CREASING CELLULOSIC FIBER STRIPS BACKGROUND OF THE INVENTION l. Field of the Invention This invention relates to a process and device for creasing cellulosic fiber strips. It relates particularly to a process and device for creasing paper strips which are advantageously utilized in covering joints between abutting wallboard edges.  
 2. Prior Art In the fabrication of cellulosic fiber strips. it is often necessary that the strips be creased as a prerequisite to their utilization in certain applications. For example. in the production of paper strips for employment in the covering and reinforcing of coplanar and corner joints formed by abutting wallboard edges (such strips being generally referred to as wallboard tape&#34;) it has been found necessary to crease the wallboard tape along its longitudinal axis. so that it may be subsequently effectively used by workmen in application to all joints. especially the corner joints. (If the tape is creased by the workman on the job without the aid of special tools. difficulty is experienced in folding the tape along a line substantially equivalent to the longitudinal axis of the tape. and the so&#39;creased tape does not readily conform to and completely overlie the joints. especially the corner joints. Although the employment of certain special creasing tools by workmen on the job docs facilitate the obtainment of a straight longitudinal fold in the tape. such adds to the overall cost of the completed job. as a result of increased time and tool charges.)  
  Accordingly. a number of production expedients have been devised for creasing cellulosic fiber strips. especially those employed as wallboard tape. The formation of a simple indentation or groove in the strip has been found to be ineffective of itself. unless the groove is deep enough to significantly weaken the strip. Furthermore, a simple folding of the strip has been found to be unsatisfactory, because the center of the strip is rendered thicker thereby. resulting in difficulties in winding on a roll. An example typifying recent expedients is the method of Peterson. et al. US. Pat. No. 3.086.328. Notwithstanding the efficacy of this and similar expedients. they are found wanting. as a close examination of their characteristics reveals. For example. Petersons technique requires that the advancing tape be first moistened centrally on both sides with water. followed by a complete soaking thereof. at which time the creasing action is accomplished. Peterson&#39;s tape is finally dried and ironed under tension to a perfectly flat condition. whence it is wound for subsequent utilization. Complicated procedures such this require increased production time and careful production control. thereby adding substantially to the cost of the product-which is unacceptable in view of today&#39;s requirements for improved products. as well as enhanced efficiency and reduced costs in manufacturing operations.  
 SUMMARY OF THE INVENTION Accordingly. it is the primary ofject of this invention to provide a simple and economical. yet highly efficient process and device for the creasing of cellulosic fiber strips, especially those to be employed as wallboard tape.  
  In accordance with the present invention. this object and these advantages are achieved. and the disadvantagcs of the prior art are obviated by providing a continuous process comprising forming a longitudinal groove in a surface of an advancing cellulosic strip and then causing the strip to bend along the length of the groove and fold upon itself.  
  An apparatus which is especially advantageously employed in this continuous process comprises (a) means for forming a longitudinal groove in a surface of the advancing strip. and (b) means for causing the strip to bend along the length of the groove and fold upon itself. such means advantageously comprising an elongated. rigid sheet the extreme longitudinal edges thereof being bent inwardly over the upper surface thereof to form a channel for guiding the course of the advancing cellulosic strip. the channel having an en trance end and an exit end. the body of the sheet being bent along the longitudinal axis thereof. the degree of flexure increasing from substantially zero at the entrance end of the channel to an infoldment at the exit end thereof.  
  Furthermore. it has been found of especial advantage if the apparatus additionally comprises adjust means positioned downstream of the exit end of the channel for adjusting the proximity of the halves ofthe plicature produced in the advancing cellulosic fiber strip.  
 BRIEF DESCRIPTION OF THE DRAWING For a more complete understanding of the present invention. reference should be made to the detailed description of the preferred embodiments thereof. which is set forth below. which description should be read together with the accompanying drawing. wherein:  
  FIG. 1 is a schematic side elevation illustrating a preferred embodiment of the process and depicting a prcferred embodiment of an apparatus according to the present invention; and  
  FIG. 2 is a perspective view of a part of the apparatus depicted in FIG. I.  
 DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawing. there is shown a continuous cellulosic fiber strip (11) being unwound from supply roll (I2) and guided by idler roll (13) so that it passes across the surface of idler roll (14). Cellulosic fiber strip (II) is advantageously a wallboard tape. which is conveniently prepared from wood pulp paper. and has a substantial portion of its cellulosic fibers extending in a direction transverse to the longitudinal axis of the tape. The tape may be provided with a multiplicity of small perforations. if desired. Idler roll (14) is a broad roll. i.e.. it has substantial length in the direction of its axis. The surface of idler roll (14) may be constructed form resilient material such as plastic or hard rubber. if desired. but this is not essential. Urged into contact with the upper surface of strip (11) as it passes over the surface of idler roll (I4) is idler roll (15). which is a narrow&#34; roll. i.e.. it has very little length in the direction of its axis. The surface of idler roll (I5) is advantageously constructed of hard. wearresistant material such as stainless steel; and idler roll (I5) is conveniently urged into contact with strip (II) along its longitudinal axis as it passes over the surface of roll (14). by means of spring (I6) or other equivalent means. Hereby. a small groove (21) is formed in one surface of strip (I I) along its longitudinal axis. the width of the groove being equivalent to the axial length of idler roll For a strip (ll) having a width of about 2 inches, acceptable widths of longitudinal groove (2|) have been found to be between about 0.005 and 0.060 inches. The depth of groove (Zl may vary between limits if desired; however. it should be between about 15 and 50 percent of the thickness of strip (ll The depth may be conveniently varied by changing the tension on spring 16). If the surface of idler roll (14) is constructed from resilient material. strip (11) exiting from rolls l4) and ([5) will have a longitudinal groove in one surface and a convex longitudinal protuberance in the other. This. although perfectly acceptable and even advantageous under certain conditions. is not essential.  
  After longitudinal groove (2i has been formed therein, strip (II) is advanced into the entrance of folding device (17) which is an elongated rigid sheet having its extreme longitudinal edges bent inwardly over its upper surface to form a channel for guiding the course of traveling strip (ll). (The construction and function of folding device (l7) are best comprehended by referring to FIG. 2.) The main body of the sheet comprising folding device (I7) is permanently bent along its longitudinal axis. the degree of flexure or bend increasing from substantially zero at the entrance end of the channel to a substantial infoldment at the exit end of the channel. i.e.. the longitudinal ends of the sheet are bent back upon themselves at the exit end of the channel. As it advances through folding device (l7). strip (11) is bent along groove (21) until a fold is produced in strip (ll) at the point of its exit from folding device (17). The tightness of the fold. i.e., the actual proximity of the halves of the plicature produced in strip (ll). is advantageously regulated by adjust means (23). which is located downstream of the exit end of the channel of folding device (17) by means of positioning bolt (22). The closeness of rods ([8), and consequently the proximity of the halves of the fold in strip (II). is regulated by loosening nuts (not shown) at the bottom of rods (18) and moving rods 18) either toward or away from each other in an elongated slot (not shown) in base plate (24).  
  After it passes through adjust means (23). strip (11 is allowed to assume its original, flat, unfolded configuration. and is wound upon roll (20) after passing over idler 19). At the position of groove (21) a permanent crease has been produced in strip (II), and strip (ll) as a wallboard tape is eminently suitable for application to both coplanar and corner wallboard joints.  
 What is claimed is:  
  1. An apparatus for producing a crease in an advancing cellulosic fiber strip, the apparatus comprising:  
 a. means for forming a longitudinal groove in a surface of the strip so that the depth of the groove is between about 15 and 50 percent of the thickness of the strip;  
 b. means for causing the strip to bend along the length of the groove and fold upon itself;  
 c. adjust means positioned downstream of the folding means for adjusting the proximity of the halves of the plicature produced in the advancing cellulosic fiber strip; and  
 d. means for allowing the cellulosic fiber strip to assume its original, flat, unfolded configuration and winding said strip in such configuration for subsequent utilization.  
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