US 3792563 A
Method of baling bundles of paper pulp comprising overwrapping the bundle with top and bottom wrapper sheets, and thereafter forming side seams and end flaps about the bale by applying a repulpable adhesive to overlapping areas of the wrapper sheets and exerting a compressive force on these adhesive-carrying areas so as to obtain bonded side seams and end flaps. Apparatus is disclosed for baling bundles of paper pulp, including means for applying a repuplable adhesive to overlapping areas of the wrapper sheets, means for forming side seams and end flaps, and means for exerting a compressive force on the side seams and end flaps.
Claims available in
Description (OCR text may contain errors)
United States Patent 11 1 Mercer et al.
145 Feb. 19, 1974 PAPER PULP BALING METHOD AND 3,327,452 6/1967 Cranston et al. 53/218 APPARATUS  Inventors: g i i s? 4360 gw Primary Examiner-Travis S. McGehee i 'j g q j Attorney, Agent, or FirmEdwa1'd T. McCabe;
Charles E. Bouton; Robert E. Blankenbaker Falrmile Rd., West Vancouver, BC; Frederick A. McDowall, 831 Fairfax Pl., Richmond, BC, all of Canada 57 ABSTRACT  Filed: May 16, 1972 Method of baling bundles of paper pulp-comprising  Appl 253760 overwrapping the bundle with top and bottom wrap- Related US. Application Data per sheets, and thereafter forming side seams and end  Continuation-impart of Ser. No. l53,669, June 16, flaps about the bale y pp a repulpable adhesive 1971, which is a -continuation-in-part of Ser. No. to overlapping areas of the wrapper sheets and exert- 50,837,June 29, 1970. ing a compressive force on these adhesive-carrying areas so as to obtain bonded side seams and end flaps.  US. Cl 53/32, 53/209, 53/218, Apparatus is disclosed for baling bundles of paper 53/387 pulp, including means for applying a repuplable adhe-  Int. Cl B65b 11/02 sive to overlapping areas of the wrapper sheets, means  Field of, Search 53/32, 209, 218, 383, 387 for forming side seams and end flaps, and means for exerting a compressive force on the side seams and  References Cited end flaps.
UNITED STATES PATENTS 2,974,461 3/1961 Demler 53/383 X 7 Claims, 8 Drawing Figures 13s 2' 7o so 1 90 201, 1 1 ,1 7 M a so 1 o 3 38 4' 4B 1 ,t/j I ,,/56 3!: 154 I 1/88 36 35 1 64- 3'1: v ,1Il '15 4 \A I VA \j E s 4 I I. 8 B4 1 1 v i l l T- l I 4315; i 19 Q o I A G) O .5) 51 l we 7-... a 33 Q 75 we "1 16 12s 5a 54 I me PATENTEDFEBI 91924 SHEET 5 BF 7 1 PAPER PULP BALING METHOD AND APPARATUS This invention is a continuation-in-part of copending application Ser. No. l53,669, filed June 16, 1971, which in turn was a continuation-in-part of application Ser. No. 50,837, filed June 29, 1970.
The present invention relates to an improved method for baling bundles of paper pulp and to improved apparatus suitable to carry out said method of baling. More particularly, the present invention relates to a method and apparatus for baling bundles of paper pulp overwrapped with top and bottom wrapper sheets by applying an adhesive to overlapping portions of the wrapper sheets and then applying a compressive force to these overlapping portions.
Generally, paper pulp is manufactured in sheet form at mills close to a source of supply of timber. Often, however, no paper mills are located at the same site as the pulp mills, and therefore the pulp must be baled and then shipped to paper mills or other customers.
At the pulp mill, timber'is processed into a continuous sheet of paper pulp comprising cellulose fibers. The
pulp sheet is passed through a dryer in order to obtain a product of desired solids content, usually between about 80% agd 100%. Once the continuous pulp sheet is formed and dried, it is auto-matically cut into rectangular sheets, and these sheets are stacked and weighed to obtain a unit weight stack. Top and bottom pulp wrappers are then loosely positioned above and below the stack. Consumer paper mills generally require the pulp stack to be wrapped in these pulp sheets in order to protect the bale contents from dirt and moisture, the wrapper sheets being eventually repulped by the consumer paper mill. The stack is then transferred to a hydraulic press which exerts a tremendous downward pressure on the stack in order to effect a compact bundie. This compression step reduces the height of the stack, correspondingly reducing the stack volume and resulting in a compact unit which can be more easily baled.
Baling is accomplished in the paper pulp art by folding the wrapper sheets about all six" sides of the pulp bundle, and then tying steel wires or straps transversely and longitudinally about the bundle. One wire may be secured lengthwise and one wire widthwise, or two or more wires may be tied about each dimension. This operation is performed automatically by wire tying machines especially adapted for the baling of paper pulp. A description of one of the more popular wire tying machines is found in U.S. Pat. No. 3,179,037 to Cranston et al. The wire tying machine automatically encircles a bundle of pulp with a strand of wire supplied by a continuous spool, .ties the wire securely, and then snips the wire from the spool. The machine can be adapted to tie several wires at different increments of length or width along the bale. Before the bundle proceeds to the tying machines however, the top and bottom wrappers must be folded about the bundle so as to form side seams and end flaps. Generally, side seams are formed first along the length of the bundle by automatically or manually overlapping the top and bottom wrappers. The bundle is then fed into a tying machine to effect a transverse wire tie about the side seams. The partially formed bale is rotated 90, and the end flanges are automatically tucked in to form end flaps. The bale is then conveyed to a second wire tying machine which will secure one or more wires longitudinally about the The baling of paper pulp with steel wire has created serious problems which plague both the pulp industry and the paper industry. For example, at the pulp mills, the use of wire presents a considerable expense. The cost of wire per bale may range from a few cents up to more than 20 cents, depending on the number of wires placed about each bale. When it is considered that a medium to large paper pulp mill may manufacture from 500 to 1,500 tons of pulp per day (about 2,000 to 6,000 bales per day), it can be seen that the cost of wire constitutes a major expense. Moreover, the complexity of the wire tying machines causes frequent mechanical problems which may require shutdown of the whole baling line, thus lowering daily production levels,
When the wire-baled pulp-reaches a paper mill, even greater problems are involved. For example, removal of the wire from the bales is difficult and timeconsuming. Also, removal of the wire often causes injury to employes, such as eye injury, due to the elastic spring of the sharp wire when it is cut from the bale. The most serious problem is that pieces of the wire sometime get into the paper beaters, scoring the rollers and cutting through the felts so .as to cause costly equipment damage. Moreover, disposal of the wire once it has been removed from the bale is a problem inasmuch as the wire has essentially no scrap value.
In view of the many serious problems created by the use of wire in baling paper pulp, those skilled in the art have long sought a better method of baling. However, to the best of our knowledge, no feasible alternative has yet been developed. One direction of inquiry by those skilled in the art has been the use of adhesives to bale paper pulp; but such efforts, for various reasons, have not been successful. In U.S. Pat. No. 3,330,409 to Jorgensen, there is disclosed a pulp bale secured by two or more paper pulp bands made endless about the stack of pulp sheets; the bands can be secured at meeting ends by the use of an adhesive such as animal glue. The Jorgensen invention however, does not contemplate the baling of pulp overwrapped with top and bottom wrapper sheets as is the general custom in the art. Moreover, the Jorgensen method requires an adhesive set time of up to 10 minutes in order to obtain a suitable bond, whereas in a typical pulp mill baling line, the bale must be bonded within from about l0 to 20 seconds. For these reasons, the Jorgensen invention does not solve the problems presented by wire-baling of paper pulp.
in U.S. Pat. No. 2,765,838 to Brown, there is disclosed a method and apparatus for packaging a stack of fibrous mats in kraft paper, using a thermosetting adhesive to bond overlapping portions of the paper. The Brown invention however, is not applicable to the problem of baling paper pulp in pulp wrapper sheets. Thermosetting adhesives are generally non-'repulpable,
i.e. not water soluble or dispersible, and thus would not be amenable to pulp baling because of the need to repulp the wrapper sheets. Thus the Brown invention does not solve the problems inherent in the baling of paper pulp.
It is accordingly a principal object of the present invention to provide an improved method and apparatus for baling paper pulp. I
Another object of the present invention is to provide an improved method and apparatus for baling paper pulp without the use of wire.
It is a further object of the present invention to provide an improved method and apparatus for adhesively bonding top and bottom wrapper sheets about the six sides of a bundle of paper pulp.
It is an additional object of the present invention to provide an improved method and apparatus for effecting greater speed and less expense in the baling of paper pulp.
It is also an object of the present invention to provide an improved baling apparatus which is interchangeable with wire tying units in a paper pulp baling line.
Another object of the present invention is to provide an adhesively bonded pulp bale wherein the wrapper sheets are suitable for repulping.
Basically, the present invention contemplates a method of baling a stack of paper pulp wherein the stack is overwrapped with top and bottom wrapper sheets. The wrapper sheets are folded about the bundle of pulp sheets so as to obtain overlapping side and end flanges to which a repulpable adhesive is applied. These adhesive-bearing flanges are then subjected to a high compressive force in order to achieve a rapid, durable bond which retains the wrapper sheets securely about the pulp bundle.
Apparatus for performing this method will comprise, in addition to means for folding the side and end flanges of the wrapper sheets, means for applying adhesive to said flanges, and means for applying a high compressivee force to the adhesive-bearing flanges.
Further objects and advantages of the present invention will. become clear from the following description of the invention taken in conjunction with the drawings, wherein:
FIG. 1 is a flow diagram ofa pulpbaling line incorporating the present invention.
' FIG. 2 is a diagram illustrating the folding sequence of a paper pulp bale.
FIG. 3 is a side elevation ofa portion of apulp baling line incorporating the present invention.
FIG. 4 is a plan view of a'portion of a pulp baling line incorporating the present invention.
FIG. 5 is a perspective view of the adhesive press means.
FIG. 6 is a plan view in partial section of one side compression plate.
FIG. 7 is a side elevation view of a portion of the side compression plate, showing'the spring-load assembly.
FIG. 8 is a schematic drawing of the hydraulic power system.
According to the method of this invention, sheets of paper pulp in the form of a bundle can be securely baled without the use of wire. The method is applicable to pulp prepared from both gymnosperms (softwood) such as spruce, hemlock, flr, pine and cedar, and from angiosperms (hardwood) such as aspen, birch, beech, maple, oak and gum. The pulp may also be prepared from old paper, rags and other fibrous raw material such as straw, esparato, jute, flax, hemp, corn stalks, bagasse and bamboo. Moreover, the inventive method is applicable to pulp prepared by different processes such as mechanical pulping, semichemical pulping, and chemical pulping including the sulfate process, the sulfite process, the soda process, and the kraft process. Of these processes, the sulfate process, and the kraft variation thereof, are probably the most important. The sulfate process is amenable to both softwoods and hardwoods, but is usually used with softwoods because of the long, strong fibers obtained.
After the pulp is formed into a continuous sheet and dried, it is automatically cut into rectangular sheets which may range from about 27 to 36 inches in width and from about 30 to 40 inches in length. The sheets are stacked and weighed so as to obtain stacks of unit weight, usually about 500 lbs. each. The stack is then compressed to reduce its volume and form a compact bundle. Thereafter, top and bottom wrapper sheets are loosely positioned above and below the bundle, either automatically or by hand. The wrapper sheets are typically cut from pulp prepared at the mill, but are cut into larger sizes than the normal pulp sheets in order to provide sufficient surface area for the sheets to completely overwrap the pulp bundle. It is important that the wrapper sheets are positioned in register with the stack. That is, there should be substantially equal projections of the wrapper sheets on both sides of the stack, and at both ends thereof, so as to insure that there will be an overlap of the top and bottom wrappers when they are folded. In this way, sufficient surface area is provided where the side and end flanges overlap to allow for adhesive bonding of the top wrapper to the bottom wrapper. It should also be noted that it is possible to use two bottom wrappers with one top wrapper, or two top wrappers with one bottom wrapper, or two of each. Usually however, only one top and one bottom wrapper will be employed.
After the wrapper sheets are positioned in register with the bundle, the side seams are formed andbonded, and then the end flaps are formed and bonded. The side flanges may be folded manually or automatically by lifting the projecting sides of the bottom wrapper upward along the length of the bundle, and forcing the projecting sides of the top wrapper downward along the length of the bundle, and into overlapping relation with the bottom wrapper. The bottom flanges could be made to overlap the top flanges, but it is preferable to overlap the bottom flanges with the top flanges.
Prior to overlapping engagement of the top and bottom wrappers along the length of the bundle, a repulpable adhesive is applied to areas of the wrapper side projections which will overlap. The adhesive may be applied to one wrapper, or both. When the top wrapper is to overlap the upward extending flanges of the bottom wrapper, adhesive may be applied to the outer surface of the bottom wrapper side flanges, or to the inner .surface of the top wrapper side flanges, or to both of said areas. The adhesive may be applied before the side flanges are urged upward and downward along the length of the bundle, or the adhesive may be applied to the flanges after they are partially folded upward and downward along the bundle but prior to actual overlapping engagement.
Application of the adhesive may be effected by any convenient means, such as spraying, extrusion, brushing, or rolling. The pattern of adhesive application can be selected as desired, and for example, may constitute a continuous thin film of from about 2l0 inches in width, a continuous bead, or an intermittent pattern. Preferably, the adhesive is sprayed to form a thin continuous band of adhesive about 5 inches inwidth along the outer surface of the upwardly extending bottom wrapper side flanges on each side of the bale.
Once the adhesive has been applied to the side flanges, they may be urged into overlapping contact. The adhesive-bearing side seams are then subjected to a powerful compressive force which drives the adhesive into the pulp wrapper sheets. Because of the deep pen- 5 etration of the adhesive into the pulp wrapper sheet, a very strong bond is obtained, and further, the adhesive will exhibit greater moisture resistance. The amount of pressure required to effect a strong, durable bond is a function of several parameters, including length of time make possible a quicker, stronger bond, it is preferable to exert a downward compressive force on the top of the bale in order that buckling and bale deformation can be prevented, while still exerting a high compressive force on the side seams. Generally, it has been found that pressures of greater than about 10 psig are required to effect a sufficient bond. As has been indicated, the upper pressure is limited only by bale deformation, and may be in excess of 350 psig. When no compressive force is exerted on top of the bale to prevent bale deformation, a preferred pressure range for effecting a strong adhesive bond is from about 10 psig to about psig.
However, as already mentioned, the preferred mode of this invention includes the simultaneous application of a compressive force on the top of the bale in order 30 to prevent bale buckling and deformation while the side seams are being bonded. This anti-buckling pressure may range up to 15 psig, and above. A preferred 'ian 'eor antiiiiickling pressure is frOrnEBoutTp sig tB S about 10 psig. It will be obvious of course, that the greater the anti-buckling pressure, the greater the side seam bonding pressure may be. When an anti-buckling pressure is applied to the top of the pulp-bale, the side seam bonding pressure applied will preferably be from about 25 psig to about 75 psig, and most preferably 4 from about 30 psig to about 60 psig.
The compression dwell time may be varied in accordance with the adhesive employed and the compressive force applied to the bale. It must be noted however that a vertical fold is required. The folding operation is generally carried out automatically by first folding the projecting side flaps sideways across the end of the bundle, and then folding the top and bottom flaps vertically to overlap the transverse fold. Preferably, the transverse fold is made first, then the bottom flap is folded upwardly, and finally the top flap is folded down over the bottom flap. When the end flaps are to be folded in this manner, adhesive may be applied to the outwardly facing surface of the bottom flap or to the inwardly facing surface of the top flap, or to both of said surfaces. The adhesive may be applied prior to folding the end flaps, or at any time during the folding thereof. As with the side seams, application of adhesive may be any convenient means such as spraying, extruding, brushing, or rolling; and the pattern of application may be selected as desired, and preferably will be a thin continuous band about 2l0 inches in width.
After adhesive has been applied to the selected surface areas of the end flaps, the flaps are urged into overlapping engagement, and the bale is then ready for the compressive bonding step. Similar to bonding of the side seams, a compressive force of greater than about 10 psig is used to obtain a good bond, 'with a range of from about 10 psig to about 30 psig being preferable when no downward, anti-buckling compression is utilized. As previously mentioned, the preferred mode of the present invention comprises the simultaneous application of a compressive force to the top of the bale in order to prevent buckling while the end flaps are being bonded. This anti-buckling pressure may range up to 15 psig and higher, and preferably will be from about 2 psig to about 10 psig. When an antibuckling pressure is applied to the top of the bale, the end flap bonding pressure applied will preferably be from about 25 psig to about 75 psig, and most preferably from about 30 psig to about 60 psig.
The dwell time for the compression is again dictated 0 by the demands of the particular baling line, and will the determining factor as to length of compression dwell time. is generally the speed of operation of the baling line. Existing automated baling lines generally require that no one operation on a bale have a dwell time of greater than about 30 seconds. Fast baling lines may have a maximum dwell time, for any one operation, of less than about 20 seconds. The present method of adhesive baling is effective to not only meet existing time requirements of baling lines, but also, can substantially reduce the time required for baling. The compression dwell time may be as low as 5 seconds when a high tack, fast dry, adhesive is employed in conjunction with a high compressive force. Preferably however, the time of compression will be greater than about 10 seconds. The upper limit of compression dwell time is limited only by the speed of the baling line, and for example, could be as long as 20 to 30 seconds.
After the side seams have been bonded by application of adhesive and compressive force, the partially baled bundle is ready for formation and bonding of the 6 normally range between about 10 and 30 seconds. Of course, the compression dwell time can be longer than 30 seconds if the baling operation so permits. Times as low as 5 seconds may effect a suitable bond where the compressive force is highand the adhesive has properties of high tack and fast dry.
The adhesive composition utilized in the present method may be any repulpable adhesive which has properties of good tack and fast set time. The adhesive may be a synthetic or natural adhesive derived. from plant or animal sources. A preferred class of adhesive compositions in the collagen protein colloids containing from about 30-50 percent collagen protein and from about 50-70 percent water. A second preferred class of adhesives is thepolyvinyl acetates containing from about 4060 percent polyvinyl acetate emulsion of 50-60 percent solids, and from about 40-60 percent water. A composition containing 50-55 percent polyvinyl acetate emulsion, 40-45 percent water and up to 10 percent of a suitable plasticizer is a particularly good adhesive for baling paper pulp in accordance with this method. Another suitable class of adhesive compositions is the repulpable hot melt adhesives having properties of fast dry and good tack. High solids content dextrine adhesives containing from about 30-50 percent dextrine and 5070 percent water are also advantageous.
Many other water soluble or water dispersible resins, while not possessing. the very rapid dry and high tack characteristics of the above-mentioned adhesives, may be used successfully in slower baling lines. These resins include polyvinyl alcohols, sodium polyaorylate, casein, carrageenin, sodium alginate, methyl cellulose, hydroxyethylcellulose, carboxy-methylcellulose, and mixtures thereof. These resins are generally compatible with the collagen protein colloids when in solution, and may be also advantageously combined therewith to provide suitable adhesive compositions for the purposes of this invention. The adhesive should be repulpable inasmuch as the consumer paper mill will ordinarily want to repulp the wrapper sheets. The presence of a non-repulpable adhesive impregnating the wrapper sheets would render them unsuitable for paper manufacture. By repulpable adhesive is meant an adhesive which is soluble or dispersible in the paper mill pulp beaters, i.e., water soluble or water dispersible. One important advantage of using the protein colloid adhesive described above is that its presence in the final paper product actually enhances the desirable properties of the paper.
It is important to apply the adhesive to the pulp wrapper sheets while in a flowable state, that is, while having a flowable viscosity, such as would be suitable for spraying or extrusion. Thus if the adhesive is normally a solid or a gel at ambient temperatures, as is generally the case with the collagen protein adhesives, it is necessary to first heat the adhesive to reduce its viscosity and thus render it flowable. Application of the adhesive while hot has the further advantage of encouraging rapid migration of the adhesive into the fiber structure of the pulp wrapper sheets during the compressive bonding step. Also, application of the adhesive while hot results in rapid evaporation of solvent, such as water, which may be present in the adhesive, and thus is conducive to quick drying. The lower temperature of application of the adhesive will thus be determined by the point at which it has a flowable viscosity, and will often be room temperature or lower for many adhesives, such as the polyvinyl acetates described above. On the other hand, the collagen protein adhesives will generally be applied at temperatures of greater than about 100F. The upper temperature of application will beset by the point of thermal deterioration of the particular adhesive employed. Collagen protein adhesives should usually be applied at less than about l80F., but some hot melt adhesives may be applied at temperatures ranging up to 400F.
An alternative method of bonding the side seams and end flaps involves perforation of said side seams and end flaps, as by punching small holes therein, during the compressive bonding thereof. In this manner, penetration of the adhesive into the wrapper sheets is greatly enhanced. Moreover, some of the pulp fibers are interlocked during perforation and compression, thus further improving the strength of the bond. These holes should be relatively small and closely spaced. For example, holes of 1/32 inch diameter spaced at 1/16 inch or A inch centers have been found beneficial in achieving good penetration of the adhesive. It is also possible to perforate the projecting sides and ends of the wrapper sheets prior to application of the adhesive.
It should be noted that the excellent results obtained by the inventive method described-herein are totally unexpected in view of the very difficult bonding job required. The bonding job is inherently difficult for at least two reasons: (I) the small amount of time available to obtain a strong bond, and (2) the bulky nature of the pulp wrapper sheets. The pulp wrapper sheets are generally about 6 times thicker than a sheet of paper, and are coarse and unfle xible, thus making the pulp difficult to fold and bond. Surprisingly, practice of the present method entails the use of as little as 1 ounce or less of adhesive per 500 lb. bale in many instances.
Apparatus for carrying out the method of the invention is illustrated in the accompanying drawings. FIG. 1 diagrammatically illustrates a typical pulp baling line into which the present invention has been incorporated. A continuous feed of pulp is cut into rectangular sheets and stacked in piles at stacking station 2. The stacks are then conveyed to weighing station 4 where unit weight stacks, usually about 500 lbs. are obtained by adding or subtracting pulp sheets. The unit weight stack is compressed at compression station 6 to obtain a compact bundle of paper pulp. Top and bottom wrapper sheets are loosely associated with the bundle at wrapper positioning station 8, and the bundle is conveyed to side seam forming station 10 where adhesive is applied to projecting sides of the wrapper sheets and these sides are folded into overlapping engagement. The overwrapped bundle is then fed to adhesive press station 12 where a high compressive force is exerted on the side seams to obtain a strong adhesive bond. Thereafter, the bundle passes to end flap forming station 14 where the projecting ends of the wrapper sheets are folded to form end flaps and adhesive is applied thereto. The bundle is conveyed to adhesive press station 16 to provide a high compressive force to the end flaps. The completed bale is subsequently transferred to unitizing station 18 where the bales may be stacked in a vertical pile and unitized by securing the pile with a metal strap. The bales are then ready for shipping and/or storage.
FIG. 2 illustrates a preferred method of folding top and bottom wrapper sheets about a paper pulp bundle. In step A, bundle 20 is loosely underlaid with bottom wrapper 21 and overlaid with top wrapper 22. Bottom wrapper 21 has projecting sides 23 (also referred to as projecting side flanges) aknges) and projecting ends 24 (also referred to as projecting end flanges). Top wrapper 22 has projecting sides or flanges 25 and projecting ends or flanges 26. In step B, bottom wrapper side flanges 23 have been folded upward against the sides of bale 20, and top wrapper side flanges 25 have been folded downward to overlap the bottom wrapper, thus forming side flaps 27 and side seams 28. In step C, the side flaps 27 have been folded transversely across the end of bundle 20, resulting in the formation of bottom flap 29 and top flap 30. Folding of this bale is completed by urging bottom flap 29 upward against the end of bale 20, and subsequently overlapping flap 29 with top flap 30. Side flaps 27, along with top and bottom flaps 29 and 30 will be referred to collectively as the end flaps.
Referring to FIGS. 1-5, pulp bundle 20 is positioned on bottom wrapper 21 and is carried in the direction indicated, by endless feed conveyor 31 which is driven by motor 32 through belt 33. Bottom wrapper folding means 34, positioned on each side of conveyor 31, includes vertical guides 35 and contoured guides 36. Contoured guides 36 are substantially horizontal at trailing edge 37, but are gradually inclined upwardly to a vertical position at leading edge 38. In this manner, guides 36 can engage the outwardly projecting side flanges 23 of bottom wrapper 21 and urge said flanges into a substantially vertical position by the time bundle 20 reaches leading edge 38. A. top wrapper 22 will be positioned over bundle 20 at this time if such wrapper has not previously been placed in register therewith.
Adhesive application means, generally 39, includes adhesive tank 40, pump 41 driven by motor 42, and applicator heads 43. Pump 41 draws adhesive through line 114 and valve 115, and supplies adhesive to applicator heads 43 through lines 46 and valves 47. Applicator heads 43 are stationarily mounted on vertical guides 35 by means of brackets 48, and are equipped with nozzles 50 which are positioned to apply a continuous adhesive band along the outer surface of bottom side flanges 23 as these flanges are conveyed in an upwardly extending position past nozzles 50. Nozzle design and pressure can be varied to achieve different patterns of adhesive application. Pump 41, applicator heads 43, and lines 114, 46 may be heated, as by electrical elements (not shown), in order to retain the adhesive in a heated condition until it is applied. Also, adhesive tank 40 may be heated in any convenient manner, as by steam or electrical heat.
Bale 20 is discharged onto endless machine conveyor 52, driven by motor 54 through belt 56, and positions bale 20 at seam forming station 10. Top wrapper folding means, generally 60, are positioned on each side of conveyor 52 and are operable to fold top wrapper side flanges 25 downward to overlap adhesive carrying bottom side flanges 23. Vertical guides 35 extend along each side of conveyor 52 to retain bottom flanges 23 in a vertically disposed position. When bale 20 is positioned opposite top wrapper folding means 60, pivotally mounted, hinged folding plates 62 are actuated to engage side flanges 25 of top wrapper 22. Folding plates 62 are moved in a downward wiping motion by pivotally attached piston rods 64 actuated by cylinders 66. FIG. 3 illustrates folding plate 62 in its downward position, in which position it is retained until bale 20 is discharged from seam forming station 10. Cylinders 66 are rigidly mounted on frames 68 which include cross members 70 and vertical members 72.
Upon completion of the side flanges folding operation, conveyor 52 discharges bale 20 onto endless adhesive press conveyor 74, driven by motor 73 through belt 75. The adhesive compression means, generally 76, includes frame 78 having vertical members 80 connected by horizontal upper cross member 82. Transverse compression plates 84 are reciprocably actuated by compression cylinders 86 mounted on vertical frame members 80. Anti-buckling plate 88 is reciprocably mounted below frame cross member 82, and is actuated by cylinder 90 mountedon frame cross member 82. When bale 20 is properly positioned at adhesive press station 12, transverse compression plates 84 and antibuckling plate 88 are actuated to engage the sides and top of bale 20 respectively.,After the desired compressive force has been exerted on the bale side seams, compression plates 84 and anti-buckling plate 88 are retracted.
Bale 20 is discharged by conveyor 74 onto endless turntable conveyor 92 which is driven by motor 91 through belt 93. A turntable 94 is associated with conveyor 92 and is operable to turn a bale resting thereon through a 90 arc. Turntable 94 is positioned in the center of conveyor 92 between conveyor flights 96, and is raised vertically by lift arm 98 bearing on index plate 100 which is rigidly attached to turntable shaft 102. Turntable 94 is rotated through a 90 arc, while in a raised position, by action of drive chain 104 mounted on shaft 102. Rotation of bale 20 through a 90 arc results in the sides of the bale being positioned transversely with respect to the direction of advance of conveyor 92.
Turntable conveyor 92 discharges bale 20 onto endless end folding conveyor 106 powered by motor 108 through drive belt 110. Conveyor 106 positions bale 20 at end flap forming station 14. End flap folding means, generally 114, is positioned in association with conveyor 106 and is operable to fold bale side flaps 27 sideways and end flaps 29 and 30 vertically. Apparatus which is particularly suitable for this operation is disclosed in US. Pat. No. 3,327,452 to Cranston et al. Generally, the end flap folding means 1 14 includes bottom flap folders 116, and top and side flap folder 118 which is suspended from carriage 120 on overhead tracks (not shown). Bottom flap folders 116 are mounted on each side of conveyor 106' and comprise a frame 122 which carries a pivotally mounted folding paddle 124 thereon. Paddle 124 is normally disposed in a horizontal direction with respect to conveyor 106, but may be swung through a 90 arc to an upright position by means of piston rod 126 which is pivotally connected to paddle 124. Piston 126 is powered by cylinder 128 mounted on frame 122. Actuation of piston 126 swings paddle 124 through the 90 arc, thus urging bottom flap 29 into a substantially vertical position, as shown in FIG. 3.
The top and side flap folder 118 comprises a top frame 130 carrying guide bar 132. Frame 130 and guide bar 132 are moved vertically by vertical cylinder 134 mounted on carriage 120 and connected to frame 130 by piston 136. Vertical hanger bars 138 are downwardly disposed from slides 140 at each end of guide bar 132. Hanger bars 138 carry transverse horizontal cross bars 142 which may be drawn together and spread apart by cylinders 144 and piston rods 146. Cylinders 144 and pistons 146 are connected to slides 140 at each end of guide bar 132.
The ends of transverse cross bars 142 carry L-shaped side flap folders 148 formed by metal plates 147 and 149. Folders 148 are normally resiliently held in a 45 position by springs 150. Stops 152 limit rotation of folders 148 in one direction, but when they engage a corner of bundle 20, they are rotated against the springs such that plates 147 are in a position perpendicular to transverse cross bars 142. In this manner, a sideways fold is effected on side flaps 27, and top and bottom flaps 29 and 30 are formed.
Top folding paddles 154 are pivotally mountedin journaled shafts (not shown) attached on either side of vertically moving frame 130. Top paddles 154 are normally held in a horizontal position but may be actuated downward through a 90 are into a vertical position by means of pivotally attached'piston rods 1 56 powered by cylinders 158 mounted on frame 130. In this manner, top flaps 30 can be folded downward to overlap bottom flaps 29.
Adhesive application means, generally 160, includes adhesive tank 162, pump 164 driven by motor 166, and applicator heads 168. Pump 164 draws adhesive from tank 162 through line 169 and valve 170, and supplies adhesive to applicator heads 168 through lines 171 and valves 172. Applicator heads 168 are fixedly mounted by brackets (not shown) on each side of conveyor 106 adjacent the bottom flap folders 116. The heads 168 are equipped with nozzles 174 which are operable to apply a suitable adhesive pattern to the end flaps of bale 20. Pump 164, applicator heads 168, and lines 169, 171 may be heated, as by electrical elements (not shown), in order to retain the adhesive in a heated condition until application. Adhesive tank 162 may be heated by any convenient means.
An alternative means of applying adhesive to the end flaps of a bale involves mounting applicator heads 168 on a moving carriage (not shown) which is operable to advance the applicator heads 168 forward and back along a defined path parallel to the direction of ad vance of pulp bales 20. The defined path can constitute a track (not shown) extending a distance equivalent to the breadth of one bale. In this manner applicator heads 168 can be synchronized to perform a two-pass application cycle in sequence with the folding of the end flaps. Thus, once folders 148 have effected a side ways fold on flaps 27, applicator heads 168 will be automatically actuated to travel forward along the defined path, applying a band of adhesive across the folded end flaps 27. It is preferable to have metal plates 147 cut out in a horseshoe design so as to enable application of the adhesive across the entire width of bale 20. Thereafter, bottom paddles 124 will be automated to fold bottom flaps 29 upward against the adhesivebearing, transverse folded side flaps 27. Subsequently,.
applicator heads 168 will be actuated to travel backwards along the defined path returning to their initial position, while applying a band of adhesive across upwardly folded bottom flaps 29. Finally, top folding paddles 154 will be actuated to fold top flaps 30 downward into overlapping engagement with adhesive-bearing bottom flaps 29.
Bale 20 is subsequently discharged onto bale press conveyor 176, driven by motor 175 through belt 177, which positions bale 20 at end flap compression station 16. The adhesive compression means, generally 76, has the same construction and operation as heretofore defined in conjunction with the description of the side seam adhesive press. When a bale is properly positioned at press station 16, transverse compression plates 84 and anti-buckling plate 88 are actuated to engage the ends and top of the 'bale respectively. Plates 84 and 88 are then retracted and the completed bale is discharged.
Referring to FIGS. -8, and describing adhesive compression means 76 with greater particularity, it will be seen that adhesive press frame 78 may be mounted on swivel wheels 180. One of the advantages of the present invention is that compression means 76 may be easily rolled into and out of a typical pulp baling line. The baling line need not be rebuilt or otherwise rearranged when employing the present adhesive press system. Thus pulp bundles may be baled with either adhesive or wire by quickly interchanging apparatus.
Compression plates 84 are actuated by piston rods 184 extending through frame members 80 into threaded sleeves 185 affixed to side mounting plates 188. Likewise, anti-buckling plate 88 is actuated by piston rod 190 extending through upper frame member 82 into threaded sleeve 191 affixed to top mounting plate 194, Hard rubber interfaces 186 may be provided between steel hinged platens 189 and side compression plates 84. Also, hard rubber interface 196 is provided between top mounting plate 194 and anti-buckling plate 88. Rubber interfaces 186 and 196 allow side compression plates 84 and anti-buckling plate 88 to flex slightly when these plates engage the bale. In this manner, the plates are able to flex sufficiently to equally distribute pressure across a pulp bale that may be improperly aligned when it enters the adhesive press means 76.
Hydraulic cylinders 86 are securely mounted on frame vertical members 80, and hydraulic cylinder is mounted on frame upper cross member 82. One end of each of stabilizer rods 206 is rigidly secured to mounting plates 188, and the other ends are reciprocably journalled through vertical frame members 80. Likewise, one end of stabilizer rod 208 is rigidly attached to top mounting plate 194, with the free end extending through frame upper cross member 82 so that rod 208 can reciprocate with plate 88. Stabilizer rods 206 and 208 prevent side compression plates 84 and anti-buckling plate 88 from tilting or rotating during reciprocation of these plates into and out of contact with the pulp bale.
A bottom support plate 230 is fixedly mounted between vertical frame members 80, and is in the same horizontal plane as feed and take-away conveyors (not shown) servicing the press 76. Support plate 230 has curved edges 232 located at both the downstream and upstream sides of the adhesive press 76 to facilitate entrance and exit of the bale. The dimensions of support plate 230 should be such that when a bale is properly positioned in press 76, the trailing end of the bale will be resting on a temporarily stopped advance conveyor at the upstream end of press 76 while the leading end of the bale will be resting on a temporarily stopped take-away conveyor at the downstream end of press 76. The center of the bale will then rest on support plate 230 so that the conveyors will not be repeatedly subjected to the full downward force generated by the antibuckling plate 88. It should be understood however, that bottom support plate 230 is not necessary for operation of the adhesive press 76. Rather, press 76 can be provided with its own endless conveyor 74 and 176.
Referring in particular to FIG. 6, it will be seen that one of the side compression plates can be mounted on the press frame in such a manner that it may be rotated in an approximately 90? arc to facilitate moving the adhesive press 76 into and out of a baling line. Hinge bolt 224 is inserted through steel bosses welded to hinged platen 189 so that side mounting plate 188 is connected to hinged platen 189, and thus to side compression plate 84, by means of a hinge arrangement. Hinged platen 189 is securely affixed to compression plate 84 by means'of bolt 183 threaded through platen 189 and hard rubber interface 186. Bolt 183 is sunk through a clearance hole in mounting plate 188, thus enabling bolt 183 to rotate with compression plate 84. In operation then, when it is desired to place adhesive press 76 in a baling line, compression plate 84, along with rubber interface 186, steel platen 189 and bolt 183 can be rotated in a 90 are about hinge and bolt 224. To prevent rotation of the compression plate 84 during normal usage, lock bolt 226 is threaded through tapped locking lug 228,, which in turn is welded to steel reinforcing platen 189.
Referring in particular to FIG. 7, it can be seen that the side compression plates 84 may be spring-loaded in order to obtain neat, attractive creases in the wrapper sheet about the whole upper periphery of the bale. When the antibuckling plate 88 is actuated downward toward the pulp bale, the sides of plate 88 will contact transverse lip 212 of the springload assembly, generally 210., forcing rod 216 and stainless steel sliding plate 217 downward. Bracket 214 and abutment 218 are stationarily mounted on side compression plate 84 such that rod 216 can reciprocate therethrough. Collar 220 is rigidly attached to rod 216 so that downward motion of rod 216 causes collar 220 to compress metal spring 222 against abutment 218.
Sliding plates 217 are made of about ,41 inch stainless steel sheet and have length dimensions approximately those of the side compression plates 84, and are vertically disposed in the same plane as compression plates 84 on opposite sides of the path of travel of the pulp bundle. The sliding plates 217 fit flush against the compression plates 84, and may extend downward along the face of plates 84 the full depth of the compression plates, or alternatively may-extend downward along the face of plates 84 only a few inches from the top thereof. Pressure applied to compression plates 84 is transmitted through the thin, steel sliding plates 217 to the pulp bundle 20. I
When transverse lip 212 and plate 217 contact bale 20, they cooperate to form a sharp crease along the edge thereof. When the bonding operation is completed and the anti-buckling plate begins to retract, compressed spring 222 will force the spring-load assembly 210 back into normal position so that the bale is free to move on the next operating station. The leading face of spring-loaded sliding plates 217 have foam rubber linings 182 with Teflon coated surfaces 181 in order to prevent tearing of the pulp wrappers during compression of the bale. Also, sliding plates 217, compression plates 84, and anti-buckling plate 88 have curved side edges 83, 85 and 87 respectively, angled away from the bale to prevent tearing of the bale wrapper during compression.
Referring in particular to F 16. 8, the hydraulic power system includes electric pump motor 234, mounted on hydraulic fluid reservoir 236. Motor 234 drives twopart gear pump 238 which in turn supplies hydraulic fluid through unloading valves 239 and 240, and then through hydraulic line 241 to four-way directional solenoid valve 242. Directional valve.242 regulates flow of fluid to side press cylinders ,86 through lines 244, 246, and to anti-buckling cylinder 90 through line 248. Fluid returns to directional valve 242 from hydraulic cylinders 86, 90 through lines 250, 252, 254 and then through filter 256 into reservoir 236.
Pump 238 A is a large volume, low pressure pump, whereas pump 238 B is a small volume, high pressure pump. Initially during a compression cycle, both pumps 238 A, B feed the hydraulic cylinders until a nomial pressure is reached and compression plates 84, 88 are in contact with the bale. Then low pressure unloading valve 240 will recycle hydraulic fluid back to the tank 236 through line 235 and filter 256. High pressure valve 239 will continue to direct hydraulic fluid to the cylinders until the desired final pressure is obtained. If pressure builds up past this desired final pressure, valve 239 will recycle fluid back to reservoir 236 through line Since anti-buckling plate-'88 is to apply a lower compressive force than transverse compression plates 84, pressure reducing valve 260 is positioned in line 248 between directional valve 242 and hydraulic cylinder 90 so as to reduce the hydraulic pressure of fluid directed to the anti-buckling unit. Sequencing valve 262 is placed in hydraulic line 244 between directional valve 242 and compression cylinders 86, and is preset at a substantially higher pressure than reducing valve 260. Therefore, reducing valve 260 will open first, passing fluid to cylinder 90 so as to actuate antibuckling plate 88 before side compression plates 84 are actuated. in this manner, anti-buckling plate 88 will contact the pulp bale before sliding plates 217 make contact, and will maintain a constant downward pressure on the top of the bale during application of compressive bonding force by the sliding plates 217 and side plates 84. Double lock valve 261 positioned across hydraulic lines 248 and 254 is operable to lock antibuckling plate 88 in both retracted and extended positions when control valve 242 is in a neutral position.
Although the adhesive press means 76 has been shown and described as operated by a hydraulic fluid system, it should be understood that a compressed air system could also be employed. A hydraulic system has been described because such a system is more versatile within ranges of high compressive force.
It will of course be understood that the amount of compressive force exerted over the side seams and end flaps of a bale during the adhesive compression step will be a function of the hydraulic or pneumatic pressure directed to the adhesive compression cylinders 86, the diameter of the piston bore, and the surface area in contact with the bale of compression plates 84 and sliding plates 217. Excellent results have been obtained by utilizing a 4 inch diameterpiston bore (cross sectional area 12.56 sq. in.), and using sliding plates 217 and compression plates 84 having the same dimensions of 30 inches by 14 inches (contact surface area of sliding plate 420 sq. in.). With pistons and plates of that size, a preferred range of hydraulic pressure will be from about 1,000 lbs. to about 2,000 lbs., which works out to an actual pressure of about 30 to 60 psig across each of the side seams and end flaps of the bale.
Likewise, anti-buckling piston bore may have a 4 inch diameter. Anti-buckling plate 88 preferably has length and width dimensions greater than the top dimensions of the bale; thus for a 30 by 33 inch bale, plate 88 could'have dimensions of 31 by 35 inches (surface area 1,085 sq. in.). Therefore a hydraulic pressure of 500 lbs. applied by the piston to plate 88 would generate an actual pressure of about 6 psig across the top of bale 20.
It should be understood that the compressive forces set forth in describing this invention necessarily must reflect an average pressure. Thus when it is stated that a compressive force of 60 psig is applied across the side seams or end flaps of a bale, this does not mean that exactly 60 psig is applied uniformly across each inch of the bale in contactwith the sliding plates and compression plates. Rather, the pressure will generally be somewhat reduced at points along the bale farthest from the center. Thus there will generally be a somewhat higher pressure applied at the center of the bales than at the outer portions thereof. 7
The side flange folding apparatus, end flap folding apparatus, turntable, and adhesive applicator units are preferably operated by a compressed air'system. The conveyor system may be operated by electric motors or pneumatic motors as desired. The various pneumatic and hydraulic cylinders are controlled by relay valves which may be actuated either by solenoids in an electric control system or by pneumatic relay valves in a pneumatic control system. In an electrical control system, which is preferred, the various operations and sequences are generally initiated by limit switches actuated by the pulp bale or by moving parts of the apparatus. For example, limit switches 264, 266 and 268 are mounted on adhesive press frame 78 to insure retraction of all compression plates before discharge of the bale. The total time of the compression cycle is controlled by a manually variable timing device (not shown).
The operating and control systems have not been illustrated fully as these are well understood in the art, and the program of operations must serve the varying requirements of each particular pulp baling line. These requirements vary to the extent that no particular control system can be considered as standard. A control system designed for one pulp mill installation would probably not be suitable for another.
Obviously, many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.
1. A method for baling bundles of paper pulp comprising: positioning top and bottom wrapper sheets, having projecting side and end flanges, in register with the top and bottom of a pulp bundle; applying a repulpable adhesive to a portion of the projecting side flanges; forming side seam bonds by folding the side flanges into overlapping relationship, then first applying an anti-buckling force of greater than about 2 psig to the top of the pulp bundle, and immediately thereafter applying a compressive force of greater than about 10 psig to said overlapping flanges for a time greater than about 5 seconds while maintaining said antibuckling force; forming end flaps in the wrapper sheets by folding said projecting end flanges; applying said adhesive to a portion of said end flaps; and forming end flap bonds by first applying an anti-buckling force of greater than about 2 psig to the top of said pulp bundle, and immediately thereafter applying a compressive force of greater than about psig to said end flaps for a time greater than about 5 seconds while maintaining said anti-buckling force.
2. The method of claim 1 wherein an anti-buckling force of from about 2 psig to about psig is applied to the top of the bale while a compressive force of from about 25 psig to about psig is applied over the side seams and end flaps for from about 10 to 30 seconds.
3. The method of claim 2 wherein the adhesive is applied in a spray pattern and is selected from the group consisting of collagen protein adhesives, polyvinyl acetate adhesives, and repulpable hot melt adhesives.
4. The method of claim 3 wherein an anti-buckling force of from about 2 psig to about l0 psig is applied to the top of the bale while a compressive force of from about 30 psig to about 60 psig is applied over the side seams and end flaps for from about 10 to 20 seconds.
5. The method of claim 4 wherein the adhesive is a polyvinyl acetate adhesive comprising from about 40-60 percent water and from about 40-60 percent polyvinyl acetate emulsion having 50-60 percent solids.
6. In a system for adhesively bonding bundles of paper pulp within top and bottom wrapper sheets having projecting side and end flanges, wherein the bundles move along a defined path, undergoing sequential operations, said system including (a) means for applying adhesive to a portion of the projecting side and end flanges of said wrapper sheets; and (b) an adhesive press means including a frame, a pair of side compression plates vertically disposed on opposite sides of the path of travel of said pulp bundle and reciprocably mounted on said frame .for horizontal movement towards and away from said pulp bundle and an antibuckling compression plate positioned above said path of travel and in the same plane as the top of said bundle and reciprocably mounted on said frame for vertical movement into and out of engagement with said pulp bundle; the improvement which comprises: providing each of said side compression plates with a spring-load assembly for effecting neat creases in the wrapper sheet about the upper periphery of the bundle, said springload assembly comprising a rigid sliding plate extending substantially flush along the leading face of said compression plate and downward across at least a portion of the depth of said compression plate such that pressure applied to the compression plate may be transmitted through the sliding plate to the bundle; and a transverse lip rigidly affixed to the top of. said sliding plate and perpendicular thereto, both said sliding plate and said lip being mounted on the compression plate by means of a metal spring, whereby actuation of the antibuckling plate forces said lip and sliding plate downward against the resistance of the spring until said transverse lip engages the top of the bundle.
7. The system of claim 6 wherein the leading face of the sliding plate is lined with foam rubber.
Patent NQ- 19;}93 UNlTED STATES PATENT OFFICE .ifill'il I H .A'IIC (")F (10R R WZll 0N Dated February 19,. 19711,
Inventofls) Cecil S. Mercer, Archibald D. Beveridge and Frederick A. McDowell It is certified that error appears in the above-identified patent and thet said Letters Patent are hereby corrected as shown below:
The patent should show an its face that it is assigned to swift 80 Company of Chicago, Illinois.
Signed and sealed this 17th day of September 1974.
(SEAL) Attest: COY M. GIBSON JR. c. MARSHALL DANN Afitesting Officer Commissioner of Patents