Abstract:
A butt splicer lengthens a travel distance of a lap-spliced web by a predetermined distance. A pair of knives, spaced apart by the predetermined distance are fired when the lap splice is between them. The severed ends of the web are brought together on a vacuum roll for the application of a tape bridging the upstream and downstream ends. In one embodiment, a second tape is applied to the second side of the web to form a double butt splice.

Description:
BACKGROUND 
     The present invention relates to converting machines and, in particular to techniques for accomplishing butt splicing in converting machines. 
     Converting machinery is used to feed a web of paper, or other product from a roll to a using process. When the web on one roll expires, the leading edge of a web on a new roll must be attached. One way for attaching the leading edge includes shutting down and stopping the web, manually severing the tail end of the web from the expiring roll, and affixing the leading edge of the new roll. This procedure, of course, requires discontinuous feeding of the web to the using process. 
     In order to permit continuous feed from the roll to the using process, it is conventional to prepare a new roll by adding double-sided tape to its leading edge. As the expiring roll is nearly depleted, the new roll is rotated up to a peripheral speed equal to the web speed. A bump roll displaces the expiring web into contact with the double-sided tape, which adheres the leading edge of the web from the new roll to the moving web. Substantially simultaneously, a cutting bar is fired to sever the tail of the old web. 
     The type of splice above described is called a lap splice. That is, the location of the splice contains the expired web, the leading edge of the new web, and the double-sided tape between the two webs. Although many processes can tolerate lap splices, there are some which cannot. For example, when the web is relatively thick, the combined thicknesses of the two overlapped webs plus the double-sided tape may be more than the downstream using process can tolerate. 
     A butt splice is one in which the trailing edge of the expiring web is abutted, not overlapped, by the leading edge of the new web. One technique for practicing a butt splice on-the-fly is disclosed in U.S. Pat. No. 5,277,731, the disclosure of which is herein incorporated by reference. In that technique, a lap splice is first prepared, substantially as in the prior art described above. Then, the tail end of the expiring web, overlapped with the leading edge of the new web, is severed. The free tail end is diverted, so that the expiring and new webs ends abut each other, with single-sided tape joining the two webs. However, the original lap splice remains attached to the expiring web upstream of the cut. This original lap splice must be removed. This is done by a further cut in the expiring web to isolate the lap splice, together with leading and trailing portions of the expiring web, still attached to the butt-spliced web. Then, the lap splice must be removed. The disclosure of the &#39;731 patent suggests forming the lap splice using a double-sided tape of limited adhesive strength, so that its adherence is weak enough to be relatively easily overcome. One way suggested for disposing of the debris is to change the web direction sharply after butt splicing so that the butt splice and new web follow the changed direction, while the debris continues generally straight ahead. Separation is aided by a fixed blade. 
     In order to thicken the lap splice, and thus improve the ability to separate the debris, the above technique adds a length of stiff material between two layers of double-sided tape. This three-layer structure is then used to form the lap splice. Several disadvantages are foreseen in the prior-art technique. The certainty of separating the debris from the advancing web may be less that perfect. The amount of labor required to lay up two layers of double-sided tape plus the stiffening material exceeds that required for a simple lap splice, thereby increasing labor cost. Finally, the debris is quite bulky, thereby complicating disposal. 
     The prior-art technique is incapable of butt splicing a double-layer web in which the top layer of the expiring web is butt spliced to the top layer of the new web, and the bottom layer of the expiring web is butt spliced to the bottom layer of the new web. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the invention to provide a butt splicer for converting machinery that overcomes the drawbacks of the prior art. 
     It is a further object of the invention to provide a butt splicer for converting machinery that lengthens the web path of a lap-spliced web, then severs the web before and after the lap splice so that, the lengthened path places the trailing end of the expiring web abutting the leading end of the new web. A single-sided tape is applied over the abutting ends to form the butt splice. 
     It is a still further object of the invention to form a butt splice in a two-layered web as described in the foregoing paragraph, and also to apply a single-sided tape over the abutting ends on the other side of the web. Thus, when the two-layer web leaves the butt splicer, the top layer of the expiring web is butt spliced to the top layer of the new web, and the bottom layer of the expiring web is butt spliced to the bottom layer of the new web. This permits downstream separation of the top and bottom layers by the using process. 
     Briefly stated, the present invention provides a butt splicer lengthens a travel distance of a lap-spliced web by a predetermined distance. A pair of knives, spaced apart by the predetermined distance are fired when the lap splice is between them. The severed ends of the web are brought together on a vacuum roll for the application of a tape bridging the upstream and downstream ends. In one embodiment, a second tape is applied to the second side of the web to form a double butt splice. 
     According to an embodiment of the invention, there is provided a butt splicer for butt splicing a web which contains a previously performed lap splice, comprising: first and second knives, the first and second knives being spaced apart a predetermined distance in a web-motion direction, means for lengthening a travel distance of the web between working positions of the first and second knives from an original travel distance by an amount equal to the predetermined distance, means for energizing the first and second knives when the lap splice passes therebetween to remove a waste portion of the web containing the lap splice, means for restoring the original travel distance of the web, whereby severed ends of the web are placed in abutment with each other, and means for applying a tape bridging the severed ends, whereby a butt splice is produced. 
     The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a simplified side view of converting machine including a butt splicer, according to an embodiment of the invention, on its downstream end. 
     FIG. 2 is a cross section of a lap splice in a web. 
     FIG. 3 is a cross section of a butt splice in a web. 
     FIG. 4 shows the functional elements of the butt splicer of FIG. 1 in its quiescent condition. 
     FIGS. 5-13 show the sequence of operation performed by the elements of the butt splicer shown in FIG.  4 . 
     FIG. 14 shows a butt splicer according to a second embodiment of the invention. 
     FIG. 15 is a cross section of a lap splice in a two-layer web. 
     FIG. 16 is a cross section of a one-sided butt splice in a two-layer web. 
     FIG. 17 is a cross section of a two-sided butt splice in a two-layer web. 
     FIG. 18 is an enlarged side view of a modification of the embodiment of the invention in FIGS. 4-14 showing the apparatus for performing the two-sided butt splice of FIG.  17 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, there is shown, a conventional turret unwind  10  followed in the travel direction of a web  12 , by a butt splicer  14 , according to the present invention. In the following, the term downstream indicates the direction of web  12  travel, and upstream indicates the opposite direction. 
     Since turret unwind  10  is conventional, a detailed description thereof is considered to be unnecessary, and is thus omitted herefrom. For present purposes, it is sufficient to note that turret unwind  10  feeds web  12  to a using process (not shown) from an active roll  16  (also called expiring roll). As active roll  16  is depleted, a new roll  18  is mounted and rotated into a position adjacent web  12 . Referring now also to FIG. 2, new roll  18  is prepared by affixing a double-sided tape  24  across its width at the leading edge of the new web  12   n . A conventional tear strip (not shown) holds down the leading edge of new web  12   n  until the critical moment. As active roll  16  nears depletion, new roll  18  is spun up until its surface speed matches the advance speed of web  12 . Then, a knife  20  is activated to sever web  12 , at the same time that a bump roll (not numbered) urges web  12  into contact with the double-sided tape. The strong adhesion of the double-sided tape is sufficient to separate the tear strip so that the new web  12  is joined by a lap splice  26  to the trailing end of the expiring web  12 . 
     After lap splicing, the portion of turret unwind  10  previously holding active roll  16  is rotated into an inactive loading position, while the portion previously holding new roll  18  is rotated into the supplying position. A replacement roll is loaded for repeating the operation. For present purposes, it is sufficient to understand that the exiting web  22  includes a lap splice  26  from time to time, as new rolls are placed in use. Exiting web  22  is fed to butt splicer  14 . 
     From FIG. 2, it is seen that lap splice  26  has a triple thickness consisting of the sum of thicknesses of expiring web  12   e , double-sided tape  24  and new web  12   n . Although many using processes can accommodate such triple thickness, many cannot. Such thickness becomes a special problem when web  12  is itself thick. As can be seen in the figure, lap splice  24  affixes the bottom of new web  12  to the top of expiring web  12   e . If web  12  consists of two layers, lap splice  26  does not permit separating the layers downstream. 
     It will be noted that butt splicer  14  may be added downstream of an existing turret unwind  10 . This adds flexibility to the user of the converting machinery. 
     The remainder of the present disclosure is directed to butt splicer  14 . 
     Referring now to FIG. 3, in a butt splice  28 , the trailing end of expiring web  12   e  is held immediately adjacent the leading end of new web  12   n  by a single-sided tape  30 . Thus, the total thickness of butt splice  28  is the sum of a single thickness of web  12  and tape  30 . Usually, the thickness of tape  30  is negligible. Thus, the using process is generally capable of continuing processing of web  12  past butt splice  28  without interruption. 
     FIGS. 4-13 illustrate only active elements of butt splicer  14 . Conventional frames, bearings, etc. are omitted from illustration and explanation in the interest of clarity of description. 
     Referring specifically to FIG. 4, the quiescent condition is shown in which web  12  passes over an entry idler  32 , in contact with, or in close proximity to, a vacuum roll  34  and exits over an exit idler  36 . The vacuum in vacuum roll  34  is turned off in this condition. In preparation for splicing, the surface speed of vacuum roll  34  is brought up to match the line speed of web  12 . 
     Referring now to FIG. 5, a nip roll  38  is actuated by a pneumatic cylinder  40  into contact with web  12 . This urges web  12  into contact with the surface of vacuum roll  34 . The drive of vacuum roll  34  has heretofore been speed control to match its surface speed to the line speed. At this point in the operation, drive of vacuum roll  34  is switched to tension control, which is regulated by a conventional dancer roll, or a force transducer mounted roll (neither of which is shown) upstream of entry idler  32 . A pair of adjustable position arms  42  (only the near one of which is shown) are rotated about their axes  44  to position a position roll  46 , spanning the pair of adjustable position arms  42 , clear of web  12 . 
     Referring now to FIG. 6, adjustable position arms are rotated counterclockwise about axis  44  to deflect web  12  outward until if faces a secondary cutoff knife  48 . Travel of web  12  continues. 
     Referring now to FIG. 7, an exit carriage assembly  50  is advanced from right to left in the drawing until an exit contour roll  52  is moved into close proximity to the surface, or in contact with the surface, of vacuum roll  34 . This causes web  12  to partially wrap the surface of vacuum roll  34 . 
     Referring now to FIG. 8, an entry carriage assembly  54  is driven into position (upward in the drawing) until an entry contour roll  56  is brought into close proximity to, or in contact with, the surface of web  12 . This completes the wrapping of web  12  about vacuum roll  34 . 
     A tape roll  58  on exit carriage assembly  50  is previously prepared with a tape (not shown in FIGS. 4-13) along its full length (into the paper in the figures). A pneumatic cylinder  60 ′ holds tape roll  58  out of contact with web  12  at this time. A primary cutoff knife  60  on entry carriage assembly  54  is held out of contact with web  12  as it passes that location on vacuum roll  34 . Secondary cutoff knife  48  is also held by its pneumatic cylinder  64  out of contact with web  12  as web  12  passes over position roll  46 . At this time, a vacuum is applied to vacuum roll  34 , drawing the wrap of web  12  into tight contact with vacuum roll  34 . This condition is maintained until lap splice  26  reaches a location between primary cutoff knife  60  and secondary cutoff knife  48 . 
     Referring now to FIG. 9, when lap splice  26  arrives between primary cutoff knife  60  and secondary cutoff knife  48 , both knives are fired simultaneously by their respective pneumatic cylinders  62 ,  64  to sever a length of waste  66  containing lap splice  26 . After performing the cuts, knives  60  and  48  are retracted immediately. The previous rotation of adjustable position arms  42 , has moved position roll  46  a distance effective to increase the length of web  12  between primary cutoff knife  60  and lay-on nip  38  an amount equal to the distance between primary cutoff knife  60  and secondary cutoff knife  48 . Thus, when waste  66  is removed, the remaining leading and trailing ends of the severed web have exactly the right length to abut each other as the web  12  downstream of secondary cutoff knife  48  is brought down against vacuum roll  34  alongside the leading edge of the trailing end. The portion of web  12  upstream of primary cutoff knife  60  remains drawn into firm contact with vacuum roll  34 . The portion of web  12  downstream of secondary cutoff knife  48  is urged into contact with the surface of vacuum roll  34  both by the applied vacuum, and by lay-on nip  38  still in firm contact with web  12  against vacuum roll  34 . Thus, the conditions for a butt splice are satisfied. 
     Referring now to FIG. 10, as the butted ends of web  12  rotate under tape roll  58 , tape roll  58  is urged by its pneumatic cylinder into contact with web  12 . This deposits the tape, previously placed along the length of tape roll  58  over the abutting ends of web  12 . In this manner, butt splice  28 , of FIG. 3, is completed. 
     Referring now to FIG. 11, upon completion of the butt splice, entry carriage assembly  54  and exit carriage assembly  50  are returned to their original positions. Vacuum is removed from vacuum roll  34 . All hydraulic cylinders are retracted. In this condition, position roll  46  is on the wrong side of web  12  to perform the next butt-splicing operation. 
     Referring now to FIG. 12, position roll  46  is removed from adjustable position arms  42 , preferably by remote control, and drops into a holder (not shown) to permit adjustable position arms  42  to rotate back to their quiescent position. 
     Referring now to FIG. 13, in preparation for the next operation, position roll  46  is again affixed in adjustable position arms to return butt splicer  14  to the condition shown in FIG.  4 . Tape is applied to tape roll  58 , whereby butt splicer  14  awaits the approach of the next lap splice. 
     Referring now to FIG. 14, a second embodiment of the invention omits exit carriage assembly  50  shown in prior figures. Instead, exit contour roll  52  is permanently positioned to remain urging web  12  into contact with vacuum roll  52 . Tape roll  58  is positioned adjacent vacuum roll  34  with a full-length strip of tape affixed thereon, awaiting energization of its pneumatic cylinder to apply the tape to web. All other elements of the embodiment in FIG. 14 are the same in structure and function as corresponding elements in the first embodiment of the invention. Consequently, further illustration of the structure and operation thereof is omitted herefrom. 
     Referring now to FIG. 15, the problem encountered in splicing a double-layer web  12 ′ is illustrated. The expiring web consists of an upper layer  12   e U and a lower layer  12   e L. Similarly, the new web also consists of an upper layer  12   n U and a lower layer  12   n L. A conventional lap splice  70  is affixed between lower layer  12   n L of the new web and upper layer  12   e U of the expiring web. There is no way except a manual method with such a lap splice  70  to separate the upper and lower layers automatically downstream of the converting machine. 
     Referring now to FIG. 16, a butt splice  74  of a double-layer web is shown produced by the apparatus in the present disclosure. That is, tape  76  is applied to the upper layers  12   n U and  12   e U. However, if it is desired to permit the using process to separate the upper and lower layers downstream of the butt splicer, an additional modification is desirable. 
     Referring now to FIG. 17, a desired double butt splice  78  for a double-layer web includes a tape  76 , applied by the apparatus previously disclosed, and a lower tape  80 . In this structure, upper layer  12   n U is connected to upper layer  12   e U, and lower layer  12   n L is connected to lower layer  12   e L. Thus, if the using process desires to separate the upper and lower webs downstream, such an operation is provided for. 
     Referring now to FIG. 18, a modified apparatus according to the invention adds a second tape roll  82  facing a back-up roll  84  downstream of exit contour roll  52 . Second tape roll  82  has been prepared with a full length of tape  80 , and is poised awaiting the arrival of the location for double butt splice to arrive. At the appropriate time, when the location of butt splice  78  arrives between second tape roll  82  and back-up roll  84 , second tape roll  82  is fired. This affixes tape  80  to complete double butt splice  78 . 
     In the foregoing, the exact means for producing motion and controlling timing is not described, since such means are conventional, and do not represent an inventive part of the present disclosure. Entry carriage assembly  54  and exit carriage assembly  50  may be moved along tracks by a suitable linear actuator, or they may be rotated into position about rotation axes. Pneumatic cylinders may be replaced by hydraulic cylinders without departing from the spirit of the invention. 
     Having described preferred embodiments of the invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention as defined in the appended claims.