Abstract:
An apparatus and method for transferring a clip formed of a predetermined number of interfolded paper products away from a stacking interfolder and refolding a plurality of loose end panels having a stack building table and first count finger assembly initially holding the clip and transferring control of the clip to a transfer clamp which refolds a first loose end panel and further having a clip destination station having a post end panels receiving the clip and finally refolding the final loose end panel.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to the field of automatic interfolding machines which interfold a stack of laminar products such as paper towels, paper tissues, and the like. In such machines, it is known to interfold adjacent products with more than one panel of adjacent products or sheets interfolded. In addition, it is also known to separate a clip or log of a predetermined number of such products from the continuously building interfolding stack. An example of an automatic separator is shown in U.S. Pat. No. 4,770,402. The separator shown in U.S. Pat. No. 4,770,402 separates products where only one panel is interfolded between adjacent products. However, it has been found that this apparatus is also capable of separating products with more than one panel interfolded. Products such as this are known in the industry as &#34;W&#34; folds. When interfolded products are produced by such equipment there are sheets remaining free after separation of the clip from the stack, and it is desirable to refold the loose sheets or panels to provide the highest quality product. Refolding the loose sheets on the bottom of the continuously building stack may be accomplished by the invention shown in U.S. Pat. No. 4,874,158. However, interfolded products with more than one panel interfolded will have multiple loose panels on the separated clip as well and it is desirable to refold those loose panels as well as the loose panels associated with the continuously building stack. 
     The present invention relates to refolding the loose panels on the separated clip or log. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a simplified side elevation view of a machine which continuously interfolds products into a &#34;W&#34; interfolded stack. 
     FIG. 2 is a simplified view of a continuously building stack of interfolded &#34;W&#34; products immediately before separation of a clip from the stack with the product folds expanded. 
     FIG. 3 is a simplified view similar to FIG. 2 immediately after separation of the clip from the stack with the product folds expanded. 
     FIG. 4 is a simplified view of the certain apparatus of the present invention showing the transfer clamp in various positions in a transfer and refolding cycle. 
     FIGS. 5, 5a, and 5b are a perspective close-up view of a clip showing certain aspects of the present invention. 
     FIG. 6 is a partial view similar to FIG. 1 showing the apparatus of the present invention at a beginning of a loose panel refolding cycle. 
     FIG. 7 is a partial view similar to FIG. 6 of the apparatus of the present invention showing a side view of the transfer clamp in various positions during the process of loose panel refolding similar to FIG. 4. 
     FIG. 8 is a partial view similar to FIG. 7 showing the transfer clamp apparatus returning to a position ready to begin a new loose panel refolding cycle. 
    
    
     DETAILED DESCRIPTION 
     Referring now to the Figures, and most particularly to FIG. 1, a &#34;W&#34; interfolding machine 10 may be seen. Machine 10 has a pair of interfoldingrolls 12, 14 shown in phantom which continuously build a stack 16 of &#34;W&#34; interfolded products. Referring now also to FIG. 2, an expanded view of the &#34;W&#34; interfolded product stack may be seen. In the continuously building stack 16, a first product 18 is interfolded with a second product20 such that end panels 18a, b and 20a, b are arranged in an overlapping ornesting relationship. Similarly, a third product 22 has a pair of end panels 22a, b interfolded or nested with end panels 20c, d of product 20. Even though the panels are shown spaced apart in FIG. 2, it is to be understood that the stack and resulting clips formed from the stack preferably have adjacent panels relatively closely spaced together as shown in FIGS. 1 and 5. FIG. 1 shows a completed clip 24 of products supported by a stack building table 26. It is to be understood that stack 16 and clip 24 define a stack building path 27 along which interfolding rolls 12, 14 build the stack 16 of continuously interfolded products 18 etseq. FIG. 1 shows a condition immediately subsequent to insertion of a first count finger assembly 28 and a second count finger assembly 30 resulting in separation of clip 24 from stack 16. 
     FIG. 2 is a simplified view of stack 16 immediately prior to separation of a clip of interfolded &#34;W&#34; products 18 et seq. wherein the first count fingers 28 and the second count fingers 30 have been inserted into the appropriate folds between respective panels during the stack building process. At this point, stack 16 is supported by the second count fingers 30 (see FIG. 1) and a clip of a predetermined number of paper products is trapped below first count fingers 28 which is subsequently separated from the stack as shown in FIGS. 1 and 3. 
     FIG. 3 illustrates an expanded view of the position of stack 16 and clip 24in the portion of a clip separating cycle shown in FIG. 1. Loose end panelsof product 22 may be refolded into the bottom of the stack 16 by front and rear fold over assemblies 32, 34 and by a package building finger assembly36 in a manner substantially the same as that disclosed in U.S. Pat. No. 4,874,158 and hence not discussed further here. As may be seen most clearly in FIGS. 1 and 3, to accomplish separation, first count fingers 28capture a clip 24 between fingers 28 and table 26 However, a proximal end panel 20c and a distal end panel 20d remain loose from the clip 24 and aredesirably refolded to maintain product quality of the clip 24 of &#34;W&#34; interfolded products. 
     Referring now to FIG. 4, a free-body diagram of a transfer clamp apparatus 40 useful for accomplishing refolding of loose end panels 20c, 20d may be seen. 
     In FIG. 4, clip 24 is retained initially between table 26 and first count finger assembly 28. At this time a pair of loose end panels 20c, 20d, extend from the product at the end of clip 24. Referring now also to FIG. 6, to initiate a clip transfer and panel refolding transfer cycle, transfer clamp 40 moves from the position shown in phantom lines to the position shown in solid lines. Clamp 40 has a set of first clamping fingers 42 longitudinally spaced apart from a set of second clamping fingers 44. Clamp 40 is moved transversely toward clip 24 in the directionof arrow 46 such that second clamping fingers 44 are received below clip 24in respective recesses 48 of table 26. Recesses 48 are interdigitated with a plurality of lands 50 to support clip 24 on table 26. As clamp 40 is extended transversely towards clip 24, an air pressure source 52 (see FIG.6) directs toward loose end panels 20c urge panel 20c against an outer surface of first count finger assembly 28 to prevent trapping panel 20d below first clamping fingers and to prevent tearing product 20. 
     Referring now also to FIGS. 5, 5a and 5b, it is to be understood that as clip 24 separated from stack 16, first count finger assembly 28 and table 26 hold clip 24 in compression to retain control of clip 24 as shown in FIG. 5a. Once the transfer clamp 40 moves transversely to the position shown in solid lines in FIG. 6, the table 26 and first count finger assembly 28 are moved apart thus transferring control of clip 24 to transfer clamp 40 as indicated in FIG. 5b. This action is indicated by arrows 54 in FIG. 7. Clamp 40 carrying clip 24 is moved transversely in the direction of arrows 56 (see FIG. 4) and then rotated in the direction of arrow 58 inverting the clip 24 such that loose end panel 20d is at the bottom of the clip 24 as shown in position 60 in FIGS. 4 and 7. Clamp 40 is then extended in the direction of arrows 62 (see FIG. 4) inserting clip24 between end plates 64, 66. It is to be understood that end plates 64, 66are preferably positioned apart a distance 80 slightly greater than a distance 82 spanned the first and second clamping fingers 42, 44. Clip 24 is then held between plates 64, 66 by a pusher plate 68 as the first and second clamping finger assemblies 42, 44 retract from between end plates 64, 66, thus leaving clip 24 between end plates 64, 66 in a conveyor 70 which subsequently indexes to move clip 24 away and position a new pair ofempty end plates (not shown) to receive a subsequent clip. 
     Referring now to FIG. 8, transfer clamp 40 is retracted in a direction of arrows 72 after discharging the clip 24 at a discharge station or destination 69 to conveyor 70. The clamp 40 is then rotated in the direction of arrow 74 (as shown in FIG. 8) to prepare clamp 40 for anothertransfer and refolding cycle. It is to be understood that alternative equipment may replace conveyor 70, for example, a carton infeed apparatus (not shown). 
     It is to be understood that machine 10 further includes clamp displacement means such as a rotary motor 76 to rotate clamp 40 and a servomotor and chain drive assembly 78 to enable moving the transfer clamp in and out of the stack building path, to traverse to the discharge station 69 and to move the clamp 40 in and out from between the end plates 64, 66 while at the discharge station. Assembly 78 is preferably made up of an endless chain 86 driving a carriage 88 secured thereto, both of which are driven by a servomotor 90 through a sprocket 92. Carriage 88 is positionable at any desired position between a pair of idler sprockets 94,96 on which chain 86 is carried. An air cylinder 84 is preferably used to provide relative motion between pusher plate 68 and clamping fingers 42,44. 
     Thus it may be seen that in the practice of the present invention, two loose end panels are refolded into the clip. The proximal loose end panel 20c resulting from separation of clip 24 from stack 16 is refolded by transferring the clip to the transfer clamp 40 from between the first count fingers 28 and elevator table 26. The distal loose end panel 20d is subsequently refolded into the clip by the insertion of clip 24 into subsequent machinery having opposing end plates 64, 66 such that end panel20d is refolded into the clip when the first clamping fingers 42 are withdrawn from between clip 24 and end plate 66. 
     Referring now again more particularly to FIGS. 5a and 5b, certain aspects of the refolding the present invention may be seen. In FIG. 5a, clip 24 iscontrolled or held by the first count finger assembly 28. After the first clamping fingers 42 move transversely to project above clip 24 in the stack building path, loose panel 20c is trapped between fingers 28 and 42.The table 26 and first count fingers 28 are moved apart in a direction of the stack building path such that the products making up clip 24 are allowed to expand against first clamping fingers 42 as shown in FIG. 5b. At this time, panel 20c is arranged in a slightly corrugated fashion between fingers 28 and 42 as may be seen most clearly in FIG. 5b. Subsequently clip 24 is withdrawn transverse to the stack building path 27, thus disengaging fingers 28 from between panels 20a and 20c. 
     Referring now most particularly to FIGS. 5, 5a and 5b, it may be seen that the first clamping fingers 42 are located above the first count fingers 28initially and that at least one of the first count fingers is positioned intermediate a pair of the first clamping fingers when the transfer clamp 40 is in the stack building path 27 such that a proximal one of the loose end panels (20c) is trapped between the first clamping fingers 42 and the first count fingers 28. The air pressure source 52 provides an air assist means for directing air generally transversely across the first count fingers 28 such that the plurality of loose end panels 20c, 20d are urged in a direction away from the transfer clamp 40. 
     The movement shown by FIGS. 5a and 5b is such that the first count fingers 28 are moved toward the first clamping fingers 42 a distance large enough to transfer control of the clip 24 to the pair of first clamping fingers and small enough to avoid permanent deformation of the proximal one loose end panel 20c when the stack building table 26 and the first count fingers28 are moved away from the clip 24. The first count fingers 28 are preferably spaced transversely apart from respective adjacent first clamping fingers 42 by a lateral distance sufficient to permit retention of clip 24 by the transfer clamp 40 without permanent deformation of panel20c when it is trapped between first count fingers 28 and first clamping fingers 42 as shown in FIG. 5b. 
     The invention is not to be taken as limited to all of the details thereof as modifications and variations thereof may be made without departing fromthe spirit or scope of the invention.