CA2035288C - Method and apparatus for tying twines into closed loops - Google Patents

Abstract

An apparatus for securing or tying twines or strings made of natural or synthetic fibers into tightly wrapped, closed loops around bales, boxes or other objects includes a twisting mechanism having a rotary spindle carrying a twine gripping unit adapted for receiving and gripping opposite end portions of a length of twine that has been loosely looped about a bale formed in the bale case of a baler, the twisting mechanism being operable for twisting the end portions of the twine together under tension so as to tighten the loop about the bale and to cause to end portions to be formed into a final configuration where a double strand exists which is twisted upon one of the opposite end portions and is coiled whereby a self-locking connection between the opposite end portions is effected.

Description

~3~

METHOD AND APPARATUS FOR TYING TWINES INTO CLOSED LVOPS
BacXqround o~ thP Invention This invention relates to an apparatus for, and a method of, securing twine loops around an object such as a bale of hay or straw or the like.
In conYentional balers, a bale is ~ormed by compressing loose ~ibrous materials such as hay or straw in the bale case of the baler and the compressed bale is gradually ~uL~ounded by strands o~ twines made o~ natural or synthetic fibers.
When a predeter~ined ~ize of bale has been achieved, a tying mechAni: of the baler is triggered into action ~or tying said strands into loops about the bale for holding the latter together for handling and transportation.
A typical tying mechanism of a baler (~or example, see U.S. Patent No. 2,926,599 granted to McClellan on March 1, 1960 and U.S~ Patent No. 3,419,30~ granted to Nolt et al on Dec. 31, 1968) includes two functional groups for each twine to be secured about a baler, namely a twine delivery meçh~nisr and a knotter ?~h~ni! . Each twine delivery ~chAni!
comprises a strand-holding or clamping unit positioned adjacent the top of a bale case through which the compressed material progressively moves; a container for holding a supply roll o~ twine; a pivotally mounted arcuate needle normally located in a home position below the bale case and having an eye adapted for receiving a strand of twine emanating ~rom the supply roll, exten~ing across the bale case in contact with a leading end o~ a bale b~ing formed and having a free end held by the strand-holding device; and a bale length measuring device operative, in response to the forming bale reaching a desired length, for causing a needle drive ~ch~ni ! to penetrate the needle through the bale, at what hec~ ~e the trailing end o~ the bale, and place a p~rtion of the strand into the strand-holding device so that two adjacent strand portions result.
Each knotter mech~n;~m cvmprises a knot-tying unit, including a rotatable bill hook, located next to the ~trand-holding device and operative to tie the two adjacent strand ~3~

portions together. A cutting device operates to sever the needle-placed portion of the strand at a location between the strand-holding element and the knot-tying unit so that the strand-holding element then hold~ what is a free end of a new length of twine ~or being tied about the next bale to be formed.
~not-tying units of this type are relatively co~plex -o~An;sms r~guiring close manufacturing and operating tolerances, and call for maintaining proper tension in the twine strands during the knot for ; ng pro~.ess. Excessive tension in the strands can result in wraps of twine ~ormed around the bill hooks during the knot forming process being too tight which prevents the completion of the knot and thus results in a mistie~ on the other hand, if the strands are too loose improper positioning of the strands for interaction with the tying components may occur which again results a mistie or poorly formed knot. Rough or corroded bill hook surfaces and even air humidity can also result in difficulty in removing the wrapped twine from the bill hook. A principal shortc-. ing of these knotting mech~n; - is that even when a knot is properly formed a substantial amount of slack remains in the twine which is then ~ied in a loop around the bale and this ~lack permits the compressed material to expand once the ~ale is ejected from the baler~ This expansion reduces the density of the bale from that achieved by the compaction device and in order to maintain a desired fin~l density in the bale the density achieved by the ¢ompaction device has to be higher, requiring additional energy input, causing increased stresses in the cQmpaction apparatus. The expansion of the bal2 al o can cause undesirable changes in the final Rhape of the bale.
Summarv of the Invention Accordingly, it is a broad object of the present invention to pro~ide a unique method of securing a length of twine in a tight loop about an object, particularly a bale o~
compressed material, in such a way that the bale is not allowed to expand once i~ is released from the compression t~

chamber of the baler and to provide an apparatus for pPrforming the method.
A more specific object of the invention is to employ a method of tightly tying a length of twine about an object, ~uch as a bale of compressed material, which ~ntails applying a twisting action on opposite end strand portions of the length of twine, while maintaining them under tension, so that the strand portions become twisted and wound together into an overlapping, multi-stranded configuration having ~ufficient self-locking effact to prevent the reversal of the twisting process by the internal tensile force developed in the length of twine by the twisting thereof.
Another object of the invention is to provide a tying mech~ni ~ , which is simple in construction, not calling for close operating tolerances, not being sensitive to the tension in the twine and for effecting the tying together of th~ twine in a self-locking tie without requiring the twine to be wrapped upon any part of the meçh~ni~ during the tying cycle.
Still another object of the invention is to provide a novel tying me~h~n;! , which utilizes a delivery r?~h~ni~
which is the same as or similar to the delivery system of the prior art delivery ?ch~nis~- but which utilizes a twine twisting unit in lieu of the twine knot-tying unit.
Yet a more specific object of the invention is to provide a twine twisting unit, as set ~orth in the previous object, which includes a rotary spindle carrying a twine gripping structure at one end thereof for receiving opposite strand end portions of a length of twine disposed about an object, such as a bale of compressed material, the spindle being supported for yieldable _vC ~nt k~ward the bale from a home positi~n spaced away from the ~ale, whereby a tension is maintained in the strands during twisting of the same with such twisting drawing the strands tightly against the bale so as to form a tight loop thereabout.
The tying method or process of this invention is as follows: The twine with sufficient length is placed around an object, such as a bale, to form a loop. The opposite ends of 2~3~253~
the length o~ twine are received by a gripping structure of a rotary twine twis~ing unit, which rotates while gripping the two twine ends to thereby twist them together into a single, double-stranded configuration forming a closed loop around the ob~ect. In the first phase of the twisting action, the two ends of the twine begin to form a twisted double strand at the gripping structure of the twisting unit, gradually advancing the twisting action toward the object, thereby tightening the loop around the object. Simultaneously, the angle between the twisted ends increases in the vicinity of the object1 The twisting action reduces the length of the twisted-together ends of the length of twine extending between the object and the twisting unit, which is compensated for by allowing the twisting unit to move toward the object, against a controlled resistive force, thereby maintaining the necess~ry tension for the proper formation sf the twisted double strand.
The second phase of the twisting process begins when the angle between the two converging ingle strands of the twine approaches 180~, at which time an overlapping twisting action begins, first winding one of the two converging strands on top of the already ~ormed double strand, beginning at th~ point where the two single strands converge into the twisted double strand, pulling and ben~;ng the double stranded length of twine toward the single strand which is being overlappingly twisted around the double stranded twine~ As ths angle between the single strand and the double strand decreases, while the twisting action continues, they become twisted together in a triple strand. The direction or sense o~ the w; n~; n~ of the single strand on top of the double strand is opposite to the direction or sense of the twisting of the two ~ingle strands which formed the double strand. The reversal of the direction of the winding produces a locking ePfect on the strands o~ the twine, preventing the unwinding o~ the twisted strands under the action of the tensile ~orce in the looped twine. During the formation of the triple ~trand, the tension in the loop of twine about the object increases, pulling the triple stranded twine against the body o~ the ~3~
object, thereby producing an additional lockiny effect against the reversal of the twisting action by the tensile force in the twine after relaasing the twine from the holding element of the twisting mech~n;1 . During both the first and second phases of the twisting action, the gripping structure of the twisting unit is allowed to follow the changes in the length of the twisted strands of the twine, while ~aintaining the necessary tension in the ~trands for proper twisting action.
Under the action of increasing torsional forces, a coil~d : 10 configuration develops in the portion of the double-~tranded twine not twi~ted into the triple strand. ~his coiling ef~ect further improves the knotting o~ the looped twine, as the large diameter of the coiled double-stranded twine does not allow it to pass through ~etween the object and the tightly held single strand of the twine forming the loop around the object.
After completing the tightly wrapped closed loop, and at a preset tension in the twisted strands, the twisting ?ch~nism automatically releases the twine.
This method of tying a twine by twisting is particularly adaptable for use with balers, as described in the Backqround o~ the Invention appearing above, and is achievable by replacing the knot-tying element with a twisting ?c-h~ni!
including a spindle mounted to a vertically pivotable frame which is spring biased away from the bale case, the ~pindle carrying a twine gripping structure for receiving and holding opposite end strand portions of a length of twine from a twine holding unit while the spindle rotates, such rotation twisting the strand portions together with the spring maintAining them - 30 in t~nsion while permitting the spindle to move against the bale.
Brief Description of the Drawing FIG. l is a schematic left side elevational view of the rear portion of a baler equipped with a twine twisting ~ch~ni- constructed in accordance with the principles of the present invention with the me~h~ni~ being shown at a point in ~3~

its operation just before tying a length o~ the twina in a loop about a bale located in the bale case.
FIG. 2 is a view taken along line 2--2 showing the twine holding device of the twine delivery ?ch~nism together with the twine twisting unit.
FIG. 3 is a side elevational Yi2W of the twine twisting mechanism.
FIGS. 4a, 4b, 4c and 4d are schematic representations of seguential stages of the twist tying process o~ a twine.
FIGS. 5a and 5b are schematic perspective view~ showing a twisting apparatus holding the ends of a loop of twine that extends around a bale, with the apparatus being shown at the initiation of twisting in FIG~ 4a and at the ending of twisting in FIGo 4b.
Descri~tion of the Preferred Embodiment Referring now to FIGS. 1, there is shown a rear end portion of a baler 10 for making rectangular bales. The baler ~0 includes a bale channel or case 12 having a tying ~ech~nism 14, including a twine delivery ?ch~n;sr 16 and a twine twisting me~h~nis 18, mounted thereon for tying twines about predet~l ine~ lengths o~ crop products compressed within the bale case. The twine delivery mechanism 16 is of more or less conventional construction, including a neadle 20 shown in a normal home position beneath the case 12 and fixed to a carrying frame which is vertically pivotally mounted to the case, a~ at 24, for permitting a drive ?chAnism 26 to periodically swing the frame so as to project the needle to traverse the bale case ~or a purpose explained bel~. The delivery ?ch~nism further includes a stationary frame 28 fixed to the top o~ the case 12 and supporting a twin~ holding or clamping unit 30 in a location for receiving a strand portion 32 of a length of twine 34 from the needle 20 when the latter is projected to traverse the bale case 12, the length of twine 34 emanating from a upply roll located within a container 36 carried by tha baler and including a ~trand portion 38 at the free end thereof which is held by the twine clamping unit 30. The twine clamping unit 30 includes a pair 2 ~ 3 ~ 2 ~ 8 of discs 40 rotatably mounted on a comm~n shaft, and each disc has ~our notches 42 spaced approximately 90~ from each other about the periphery of the disc. The unit 30 also ha~ a press arm 43 that is positioned betwsen the discs 40 and cooperates with the latter to exert pressure on twine strands moved thereagainst to thus hold the strand~ firmly through about 180~ rotation of the discs, after which the strands are released. The discs 40 are power driven in a well-known manner to perform a one-quarter revolution in synchronization with the movement of the needle ~0, whereby the notches 42 are properly positioned to rP~eive the twine strand portion 32 delivered by the nePdle, and through the one-~uarter turn deliver the two strand portions 32 and 38 of the length of twine 34 to the work area of the twine twisting mech~i e .
The synchronous action of the needle 20 and of the discs 40 is produced by a clutch 44 which controls both, and which is released by a bale length control device of which only a star wheel 46 is shown, the latter being positioned for being rotated by the forming bale as the latter advances along the bale case 12. ~he clutch ~4 and bale length control device may be may be fashioned in a manner similar to that disclosed in U.S. Patent 3,931,760 granted to Cheatum on 13 Jan. 1~76 while the twine holding unit may be like that disclosed in Patent No. 2,723,871 granted to Rudeen on 15 Nov. 1955 or in the aforementioned U.S. Patent No. 2,926,599.
The twine twisting -ch~ni ! 18 comprises a frame 48 pivotally mounted on the stationary frame 28 for swinging towards and away from the latter abvut a horizontal transverse pivot axis 50; and a twisting unit 52 including an upright spindle 10 is rotatably mounted to the frame at a location to allow the twine holding unit 30 to deliYer the captured twine to the work area of a twine-catching finger 56 in the ~orm o~
a wire or rod which extends somewhat spirally from a lower location of the ~pindle about which an inner end i~ recei~ed and held in place by a nut 58 which is threaded onto the bottom of the spindle 54, the nut urging an inner end of the ~inger against the bottom of an upwardly dished conical twine-~ ~ C~

gripping plate 60, which is biased downwardly against the finger by a coil compression spring 62 captured on the ~pindle between tha plate 60 and the frame 48. Thus, it will be appreciated that the amount o~ pressure transferred to the inter~ace b~tween the finger and plate 60 can be adjusted by repositioning the nut 58 on the spindle 5~. As can best be seen in FIG. 3, the finger 56 diverg2s slightly ~rom an inner to an outer location of the plate. The spindle 54 has a belt pulley 64 fixed at thè upper end thereof a drive belt (not shown) may couple an appropriate drive source to the spindle for either driving it intermittently or continuously to produce the necessary twisting or winding of the twine strand portions 32 and 38 to form a self-locking tightly wrapped loop around a bale 66 formed in the bale case 12. The pivotable frame 48 of the twisting ~h~n;~ 18 is held at its upper home position by an extension spring 68 having its opposite ends attached to the stationary frame 28 and the frame 48.
The spring 68 also exerts the necessary tensile force in the twine strand portions 32 and 38 during the twistiny action, as is explained below in more detail. Mounted on the frame 48 is a knife 70 having a cutting edge located to interact with the twine pulling action of the finger 5~ and the twine-gripping plate 60 to thereby cut the twine strand portions 38 and 32 at a location between the twine-gripping plate 60 and the twine holding unit 30.
Referring now also to FIGS. 4a - 5b, the method of tightly looping a length of twine about the bale 66 is discussed with it being understood that other objects may be similarly wrapped by using any appropriate twisting ~ch~n;~ .
Specifically, beg;nnin7 with the baler 10 in a cycle of operation where a new bale is just starting to be formed, the needle 20 will be located below the bale case 12, and a length of twine 34 will extend therefrom across the leading end of the forming bale with the strand portion 3~ at the free end of the length of twine 34 being held by the twine holding unit 30. As the forming bale gradually progresses toward the rear of the bale case, the tine is pulled from the supply roll ~3~

located in the container 3~ and extends along the top, leading end and bottom of the bale. Upon the bale reaching a predetermined length, as measured by the star wheel 46, the needle and holding unit drive mechanism 26 will be triygered to cause the needle 20 to traverse the bale case and place the strand portion 32 in one of the set of notches 42 of the discs 40 alongside the strand portion 38. The pair of discs 40 are then caused to index 90~ while the needle 20 returns to its home position. The tying ?c-h~ni~m 14 is then in the condition illustrated in FIG. 1, with the twisting unit 52 being shown in its home position wherein it is spaced upwardly from the bale 66, thi~ position being that of the twi~ting unit 52 depicted Sch- -tically in FIG. 5a.
The spindle 54 is then caused to rotate resulting in the finger 56 engaging the twine strand portions 32 and 38 and forcing them batween the twine-gripping plate 60 and an inner portion of the finger 56. At the same time, the strand portions 32 and 38 are wiped against the cutting edge of the knife 70 resulting in it being cut at a location between the holding unit 30 and the twine twisting unit 52. Further action of the twisting unit 52 will cause the respective twisted configurations illustrated in FIGS. 4a - 4d.
- Specifically, in the first stage of twisting, shown in FIG.
4a, the single strand portions 32 and 38 are shown twistPd into a double strand 72. Then, as the twis~ing continues into the second stage, shown in FIG. 4b, the angle between the strands 32 and 38 approaches 180~ as the tension in the twine increases. The interaction between ths increasing angle and the increasing tension in the two strand portions of the twine cause the pulling of the double strand 72 toward the single strand portion 38, resulting in an overlapping winding 74 of the double strand 72 and the single strand 38 into a triple strand 76, the direction or sense of which is opposite to that of the double strand 72, this latter configuration being shown 35 in FIG. 4c. FIG. 4d illustrates the final stage of the process when under the increasing torsional forces on the double strand 72, and with the increasing tension in the 2 ~ ~

strand portions 32 and 38, a coiling configuration 78 of the double strand 72 develops. At this point, the gripping force applied between the finger 56 and the plate 60 of the twisting unit 52 of the twisting ?ch~ni is overcome by the force generated in the twine and the strand portions 32 and 38 are pulled free *rom the holding element. At th~ point just before the strand portions are pulled free, the twisting unit 52 will be positioned against the bale ~FIG. 5b), the twisting unit 52 having been pulled into this position against the action of the spring 66 by the progressive foreshortening of the strand porti~ns 32 and 38 caused by the twisting action.
Thus, it will be appreciated that the tension in the spring 66 ¦ maintains an appropriate tension in the strand portions 32 and 38 as the latter are being twisted. Upon the strand portions 32 and 38 pulling free from the twisting unit 52, the stretched spring 66 ~e~uLI.s the twisting unit to its home position (FIGS. l and 5a). At this point the twine ls tightly looped about the bale with the coils 78 and hack-twistad triple strand 76 cooperating for preventing the twisted end portions of twine from untwisting.

Claims (6)

1. A method for securing in place a length of twine looped about an object and having opposite ends defined by first and second strand portions, comprising the steps of:
a) placing the first and second strand portions together, b) twisting the first and second strand portions into a double strand forming a tightly wrapped closed loop of twine about the object, c) continuing the twisting action and causing a portion of one of the first and second strand portions to be twisted together with a portion of the double strand to thus form a triple strand with the direction and sense of the winding of the double strand and said one of the first and second strand portions being opposite to the direction and sense of the twisting of the first and second strand portions forming the double strand and in this way producing a knotting effect on the looped twine, preventing the reversal of the twisting of the strand portions of the twine under the action of tensile forces acting on the looped twine and thereby securing the looped twine about the object, and d) continuing the twisting action of the double strand to cause a portion thereof not involved in forming the triple strand to form a coiled configuration until the twine tightly engages the object.

2. A tying mechanism for securing together opposite end portions of a length of twine looped about an object to be packaged, comprising: a support frame mounted for pivotal movement between a home position spaced away from the object and a second position located adjacent the object; biasing means coupled to the frame for yieldably biasing the frame to its home position; a spindle rotatably mounted to the frame for movement therewith toward and away from the object; a twine gripping means mounted to the spindle for tightly releasably holding the opposite end portions of the twine when the frame is in its home position while the spindle rotates to sequentially twist the twine end portions together into a twisted double strand, then into a configuration where the double strand is back-twisted upon one of the twine end portions and finally into a configuration where a portion of the double strand is coiled, the twine gripping means then releasing the twine end portions.

3. In combination with a baler including a bale case for receiving compressed material to be packaged into bales by looping twines about preselected lengths of the compressed material and a twine delivery mechanism mounted on the bale case for periodically looping a length of twine about a given preselected length of compressed material with strand end portions of the length of twine being held together by a twine holding unit located on the bale case, a twine twisting unit for tightly tying the length of twine about the bale comprising: a support mounted for movement between a home position spaced from the bale case and a second position next to the bale case; a spindle rotatably mounted to the frame; a twine catching means mounted to the spindle for engaging said strand end portions upon rotation of the spindle when the support is in said home position; a twine gripping means mounted on the spindle for cooperating with said twine catching means for gripping the twine end strand portions during rotation of the spindle with a force sufficient to resist the strand end portions being pulled loose from the twine gripping means by a tensile force applied to the strand end portions by said resilient means during rotation of the spindle; said tensile force being sufficient for causing, during rotation of the spindle, the strand end portions to be twisted together to first form a double strand and then to reverse-wrap a portion of the double strand about one of the strand end portions and then to cause coils to be formed in the that portion of the double strand which is not double wrapped, whereby the twine end strand portions are twisted together in a manner which resists untwisting thereof.

4. The invention defined in claim 3 wherein the twine catching means includes a finger which extends outwardly from the spindle.

5. The invention defined in claim 4 wherein the twine gripping means includes a conical plate mounted on the spindle adjacent the finger; and said finger converging toward a surface of the conical plate in the direction of the spindle so as to form a progressively narrowing gap for receiving the twine end strand portions.

6. The invention defined in claim 5 wherein the twine gripping means further includes adjustable resilient means for biasing the finger and plate together with a preselected force to thereby permit the gripping force to be changed in order to ensure that the twine end strand portions will remain positively gripped during the twisting process.