Abstract:
A knotter had a twine holder, a bill hook, an arm carrying a crotch and a cutter and a twine finger operated by a drive mechanism to form two knots consecutively, the first to tie together two runs of twine passed around a completed bale and the second to tie together two runs of twine drawn from respective supply rolls for the commencement of the next bale. The twine holder serves to grip the two runs of twine drawn from the supply rolls throughout the formation of the two knots. The bill hook serves to knot the runs of twine gripped by the holder. The cutter serves to sever the runs of twine between the holder and the bill hook. The crotch pushes the twine runs off the bill hook during the completion of each knot. The twine finger is pivotably mounted on the opposite side of the bill hook from the twine holder to bring the sections of the runs of twine to be knotted within the reach of the bill hook. In the invention, an edge of the twine finger contacting the runs of twine as the knots are pushed off the bill hook by the crotch comprises an obstruction to resist movement of the runs of twine in a direction transverse to their length.

Description:
[0001]    This invention relates to a knotter for binding bales of harvested crop material or other substances so that the bales may be handled, stored or otherwise manipulated without breaking apart. 
       BACKGROUND OF THE INVENTION 
       [0002]    Bales are often prepared under conditions of substantial pressure so that the finished product is considerably more dense than the loose material from which it is made. 
         [0003]    While it may generally be stated that increased density in such bales is a highly desirable objective, obtaining that goal has in many respects been thwarted because of the limitations of conventional wire and twine tying mechanisms. Beyond a certain level of tension in the wire or twine strands, the mechanisms experience difficulty in holding on to the strands and manipulating the same through the various motions involved in tying the opposite ends of the strands into a satisfactory knot or other type of connection. Moreover, the strands themselves can only withstand certain levels of tension before they will break. 
         [0004]    In balers that make a single knot in each loop of twine encircling a bale, one area in which substantial tension is created in the strands stems from the procedure of pulling the strands between the tightly abutting ends of a previous bale and the one being formed in order to progressively lengthen the material in the loop until the forming bale reaches its predetermined size, at which point the opposite ends of the loop are simply tied together and the bale is thereby securely bound. The need to pull the strands between the abutting bales in this manner arises because each strand has one end thereof retained by the tying mechanism while the rest of the strand is draped across the bale chamber. As the growing bale is pushed through the chamber, it presses against the strand draped across the chamber and, because one end is anchored at the tier, the strand must be pulled between the bales by the tier in order to increase the length of the strand along that side of the bale adjacent the tier. While the tension may be relatively low in the strand along its length between the source of supply and the bales, the tension will necessarily be quite higher along that length from the bales to the tier. It is along this latter length that troubles arise. 
         [0005]    To overcome this problem, baling machines have been proposed in which each loop comprises two knots. Two runs of twine drawn from two separate supply rolls are knotted at the commencement of formation of a bale. As the size of the bale increases, more twine is drawn from the supply rolls but neither run of twine needs to slide over the surface of the bale and the formed knot remains in the same place on the bale as it increases in size. At the end of a bale forming cycle, two knots are formed in the two twines, the first to tie the completed bale and the next to commence the next bale. 
         [0006]    A baler employing such a knotting system is disclosed in U.S. Pat. No. 4,142,746 the drawings and description of which are reproduced below as background to the present invention, which is concerned with an improvement in one of the components of the knotter used in the baler of that patent. 
         [0007]    As will become apparent from the detailed description of U.S. Pat. No. 4,142,746 which follows, the knotter comprises a twine holder which tightly grips the two runs of twine to be knotted for the entire duration of the process of tying the two desired knots. A device known as a bill hook rotates in front of the twine holder to form the knots and a cutter separates each knot as it is formed from the twine runs gripped by the holder. A twine finger arranged below the bill hook is pivoted to bring the runs of twine within the reach of the bill hook at the commencement of formation of each of the two knots. 
         [0008]    During the formation of the first of the two knots, that is to say the knot used to complete a loop wrapped around a bale, the twine is kept in tension by the compressed bale and this results in a tight knot with long tails projecting from the knot. Such a knot has no tendency to come undone during handling of the bale. During the formation of the second knot, on the other hand, the runs of twine still gripped by the holder are only under the tension of the runs of twine drawn from the supply rolls. These runs may have a spring arm for taking up slack and a friction device to resist unraveling of the rolls but the tension cannot be set too high on account of the noise and wear that the high tension would cause during the formation of the bales. As a consequence, the second knot is currently not as tight as the first and has shorter tails protruding from it. Because of this, the second knot, i.e. the knot tying the twine runs to each other prior to formation of a new bale, risks become unfastened while the bales are being handled. 
       SUMMARY OF THE INVENTION 
       [0009]    According to the present invention, there is provided a knotter comprising a twine holder, a bill hook, an arm carrying a crotch and a cutter and a twine finger operated by a drive mechanism to form two knots consecutively, the first to tie together two runs of twine passed around a completed bale and the second to tie together two runs of twine drawn from respective supply rolls for the commencement of the next bale, wherein the twine holder serves to grip the two runs of twine drawn from the supply rolls throughout the formation of the two knots, the bill hook serves to knot the runs of twine gripped by the holder, the cutter serves to sever the runs of twine between the holder and the bill hook, the crotch pushes the twine runs off the bill hook during the completion of each knot and the twine finger is pivotably mounted on the opposite side of the bill hook from the twine holder to bring the sections of the runs of twine to be knotted within the reach of the bill hook, characterised in that an edge of the twine finger contacting the runs of twine as the knots are pushed off the bill hook by the crotch comprises an obstruction to resist movement of the runs of twine in a direction transverse to their length. 
         [0010]    The obstruction may be a rounded projection on the edge of the twine finger, which preferably meets the edge from which it projects at a sharp corner. 
         [0011]    Preferably, the side of the projection that makes contact with the runs of twine extends substantially at right angles to the edge of the twine finger. 
         [0012]    As the bill hook rotates to complete the formation of the second knot, the two runs of twine slide along the edge of the twine finger. By providing an obstruction along this edge to resist movement of the twines, the section of the twine runs that includes the second knot to be under higher tension than the section drawn from the supply rolls and in this way achieves a superior knot without increasing the force needed to draw twine from the two supply rolls. 
         [0013]    This may produce a tight second knot with long tails without a large increase in the force needed to draw twine from the supply rolls. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The invention will now be described further, by way of example, with reference to the accompanying drawings, in which: 
           [0015]      FIG. 1  is a fragmentary, elevational view of a baler utilizing a tying apparatus; 
           [0016]      FIG. 2  is a diagrammatic view of a complete and a partial double-knotted loop; 
           [0017]      FIG. 3  is an enlarged, fragmentary, elevational view of the tier, needle and associated mechanisms in mid-cycle; 
           [0018]      FIG. 4  is a fragmentary, plan view thereof taken substantially along line  4 - 4  of  FIG. 3 ; 
           [0019]      FIG. 5  is a fragmentary, front perspective view of the tier with strands draped across the bill hook and held by the retaining discs in readiness to prepare a knot; 
           [0020]      FIG. 6  is a fragmentary, elevational view of cams on the drive shaft of the tier for operating the slack take-up arm and the twine finger which assist during the tying operation; 
           [0021]      FIGS. 7-16  are fragmentary, schematic views which illustrate the steps in the double-knotting operation; and 
           [0022]      FIG. 17  is an enlarged, front elevational view of the tip of the needle which presents the strands to the tier, illustrating details of construction thereof. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0023]    In the description which follows and in certain passages already set forth, the principles of the present invention will be described in terms of “twine” and “knots” formed in such twine. However, it is to be recognized that such principles extend to wire and twisted junctions of wire as well as twine and knots. The claims should be interpreted accordingly. 
         [0024]    The baler  20  illustrated in  FIG. 1  has a rectangular bale case  22  that happens to be supported for over-the-ground travel by one or more ground wheels  24 . The bale case  22  defines a bale chamber  26  that happens to be loaded through a curved duct  28  approaching the case  22  from the bottom thereof. A plunger  30  reciprocates within the bale case  22  to intermittently pack fresh charges of material from the duct  28  rearwardly in the chamber  26  in the direction of the arrow  32 . When the bale reaches a predetermined size, a trigger  34  is pulled by a rod  36  connected to a suitable bale length sensor (not shown) to engage a dog clutch  38 . This connects a tier  40  and its needle  42  to a source of driving power from the drive chain  44  associated with the clutch  38  whereby to initiate the tying operation. 
         [0025]    The needle  42  is mounted on the bale case  22  by a pivot  46  and is swung back and forth across the bale chamber  26  by linkage  48  which becomes activated by the clutch  38 . The needle  42  has an “at-home” or rest position fully below the bale case  22  as illustrated in  FIG. 1  and a “full-throw” position extended completely across the bale case  22  as illustrated, for example, in  FIG. 8 . As illustrated perhaps most clearly in  FIGS. 3 and 17 , the tip  50  of needle  42  has an eyelet  52  defined therein by the opposed furcations  54  and  56  of the bifurcated tip  50  in conjunction with a pair of longitudinally spaced, transversely extending rollers  58  and  60 . It will be noted that the roller  58  is positioned inwardly from the outer extremity of the tip  50 , while the roller  60  is positioned outwardly from the roller  58  more closely adjacent such extremity. Even so, the roller  60  is positioned a short distance inwardly from the outer extremity of the tip  50 , and both of the rollers  58  and  60  may be tapered toward their mid points so as to provide secure seats for the tying strands as will later become apparent. 
         [0026]    As will also become apparent, while the structures  58  and  60  have been illustrated in the nature of rollers, they may in fact take the form of stationary transverse structures such as cross pins. 
         [0027]    It is suggested at this point that reference be made to  FIG. 2  which shows the nature of the binding loop that is involved in the present invention. By reference now to this illustration, it is felt that the details of construction hereinafter described, and the operation hereinafter explained will become more easily understood. 
         [0028]    To this end, it is to be noted that the finished product is in the nature of a complete loop  62  that will completely circumscribe the finished bale. The loop  62  is made from two strands of binding material, i.e., one strand  64  along the normally top side of the bale and a second strand  66  along the normally bottom of the bale and its two opposite ends. The strands  64  and  66  thus fully circumscribe the bale and are circumferential complements of one another. Two knots  68  and  70  appear in the loop  62  at those locations where the strands  64  and  66  are substantially end-to-end. 
         [0029]    To the left of the loop  62  is a partial loop  62   a  which is in the process of being formed. Note that the top strand  64   a  emanates from a source of supply  72 , while the bottom strand  66   a  emanates from an entirely separate, second source of supply  74 . At the particular point in the sequence chosen for illustration, the knot  68   a  is in existence, and the bale is approaching that length where the needle  42  is ready to swing into operation and present the strands  64   a  and  66   a  to the tier  40  to complete the second knot  70   a  (not shown). 
         [0030]    With this short explanation in mind, the details of construction as illustrated primarily in  FIGS. 3 ,  4 ,  5 , and  6  may now be described. The tier  40  is identical in many respects to a “Deering” type knotter available from P. D. Rasspe Sohne, Hamburg, West Germany. That is to say, the components of the tier  40  which cooperate to form each of the knots of a bale may be identical to those in a unit provided by the Rasspe Company. However, the means for operating such components to produce a double knot must be different. In the illustrated embodiment, these means include a generally circular element  76  that is secured to a drive shaft  78  for rotation with the latter through one full revolution when the clutch  38  is engaged. The shaft  78  is supported by a forwardly inclined frame  80  attached to the top of the bale case  22 , and the frame  80  also supports the above-mentioned components for forming the knots in response to rotation of the element  76 . 
         [0031]    Briefly, such components include a rotary bill hook member  82  supported by the frame  80  for rotation about an inclined axis  84 , a multi-disc holder  86  rearwardly adjacent the bill hook  82  for holding strands  64   a  and  66   a  in position for engagement by the bill hook  82  during rotation of the latter, and means for releasing the connected strands from the holder  86  in the form of an arm  88  pivoted to the frame  80  by a bolt  90 . The lower end of the arm  88  is forked, defining a crotch  92  that opens away from the holder  86  beneath the bill hook  82 . The crotch  92  carries a cutter  94  between the bill hook  82  and the holder  86  for severing the strands  64   a,    66   a  in response to swinging movement of the arm  88  in the proper direction. Such movement of the arm  88  to operate the cutter  94  also serves to engage the proximal areas of the crotch  92  with a knot formed on the bill hook  82  for stripping such knot off of the bill hook  82 . 
         [0032]    In order to transmit driving power from the element  76  to the bill hook  82 , the latter is provided with a gear  96  which is disposed for meshing engagement with a pair of circumferentially spaced gear stretches  98  and  100  on the element  76 . Similarly, driving power is transmitted to the discs of the holder  86  through a worm gear drive  102  and a bevel gear  104  in position for sequential meshing engagement with a pair of circumferentially spaced gear sections  106  and  108  on the element  76 . Power to swing the arm  88  about the pivot bolt  90  is obtained through a cam follower  110  at the upper end of the arm  88  beyond the pivot bolt  90  which is disposed within a cam track  112  on the element  76 . A pair of circumferentially spaced cam shoulders  114  and  116  in the track  112  are positioned to sequentially engage the follower  110  to operate the latter. 
         [0033]    A finger  118  is located below the bill hook  82  and the crotch  92  of the tier  40  and is mounted on an upright pivot  120  for lateral swinging movement between a standby position illustrated in  FIGS. 3 and 4  and a full-throw, laterally extended position somewhat beyond that illustrated in  FIG. 5 . An operating link  122  attached at one end to the finger  118  and at the opposite end to a crank  124  serves to effect swinging of the finger  118 . The crank  124  is in turn fixed to a transversely extending shaft  126  that extends to a point behind the element  76  where it carries a second crank  128  as illustrated in  FIG. 6 . The crank  128  is biased upwardly in a counter clockwise direction by a coil spring  130  and carries a cam follower  132  at its outermost end. The follower  132  is in position for operating engagement with a double-lobed cam  134  fixed to the shaft  78  for rotation therewith, the lobes  135  and  138  being circumferentially spaced apart in accordance with the desired timed relationship between the finger  118  and the knot-forming components of the tier  40 . 
         [0034]    Also mounted on the shaft  78  with the cam  134  is a second cam  140  having a peripheral land stretch  142  over approximately 180 degrees of its circumference and a peripheral valley stretch  144  over the remaining approximately 180 DEG of its circumference. Such stretches  142  and  144  are disposed for operating engagement against a cam roller  146  located at the outer end of a lever  148  that is fixed at its inner end to a transverse shaft  150 . The lever  148 , and hence the shaft  150 , is resiliently biased in a counter clockwise direction viewing  FIG. 6  by a coil spring  152 , and the shaft  150  extends back out to the opposite side of the element  76  in parallelism with the shafts  78  and  126  to a point substantially in fore-and-aft alignment with the bill hook  82 . 
         [0035]    At that location, the shaft  150  fixedly carries a rearwardly extending slack take-up device  154 . The device  154  carries a pair of spaced rollers  156  and  158  at its rearmost end around which the strand  64   a  is entrained as illustrated in  FIG. 3 . A length of the strand  65   a  is also looped upwardly around another roller  160  disposed above the device  154  and carried by the tier frame  80  adjacent the drive shaft  78 . 
         [0036]    Noteworthy also at this point is the fact that the strand  64   a  may be frictionally clamped between a pair of opposed plates  162  and  164  ( FIG. 3 ) of a tensioning unit  166 . The force with which the plates  162  and  164  clamp the strand  64   a  may be controlled by a wing nut  168  operating against a spring  170  that in turn presses against the shiftable plate  164 . A tensioning unit similar to unit  166  may also be provided for the strand  66   a,  although such additional unit is not illustrated. 
         [0037]    Operation 
         [0038]    The condition of the partial loop  62   a  in  FIG. 2 , and that of the tier  40  and the needle  42 , corresponds substantially with conditions illustrated in  FIGS. 3 ,  4  and  7 , with the exception that in  FIG. 2 , the needle  42  is still in its home position. At this time, the bale has reached its desired length and it is time to complete the loop around the bale and make the second knot in the loop. Note that the strand  64   a  stretches along the top of the bale directly beneath the crotch  92  of the arm  88  but, at least for all effective purposes, is out of contact with the tier  40 . 
         [0039]    As illustrated in  FIG. 7 , as the needle  42  swings upwardly toward the tier  40 , it carries with it the strand  66   a  as the latter is paid out by source  74 . Note also that because the strand  66   a  is threaded through the eyelet  52  of needle  42 , a length of that strand on the twine source side of the needle  42  is also carried upwardly toward the tier  40 , such extra length being hereinafter denoted  66   b.    
         [0040]    During the time that the needle  42  approaches the tier  40 , no additional length of the strand  64   a  is pulled from the source  72 . Even as the tip of the needle  42 , and more particularly the roller  60 , snares the strand  64   a  as illustrated in  FIG. 8  and presents strands  64   a  and  66   a  in unison to the tier  40 , still no additional length of the strand  64   a  is pulled from source  72  because the device  154  rocks upwardly in a counter clockwise direction to provide the slack necessary in the strand  64   a  to accommodate the needle movement. In presenting the strands  64   a  and  66   a,  the needle  42  actually drapes the strands across the bill hook  82  and thence into awaiting notches of the holder  86 , whereupon rotation of cooperating discs in the latter serve to firmly grip the strands and prevent their escape as the bill hook  82  begins its rotation as illustrated in  FIG. 9 . Note that during the time that the strands are being delivered across the bill hook  82  to the holder  86 , the finger  118  is actuated to swing inwardly and engage at least the strand  66   a  as illustrated in  FIGS. 8 and 9  for the purpose of seating the same deeply within the crotch  92  so as to assure that the strands  64   a  and  66   a  are both in proper position across the bill hook  82 . 
         [0041]    The foregoing movements on the part of the bill hook  82  and the holder  86  are, of course, brought about by operable interengagement of the gear stretch  98  and gear section  106  on the element  76  with their respective gears  96  and  104  on the bill hook  82  and the holder  86 . Such driving interengagement continues until a knot has been formed on the bill hook  82  as illustrated in  FIGS. 10 and 11 , by which time the needle  42  has begun to withdraw. At this point, the cam shoulder  114  of the element  76  comes into engagement with the roller  110  of the arm  88  so as to swing the bottom of the latter, and hence the cutter  94 , across that portion of the strands between the bill hook  82  and the holder  86 , thereby severing the same as illustrated in  FIG. 11 . Such motion of the arm  88  also strips the finished knot  70   a  from the bill hook  82  and drops the completed loop on the bale as illustrated in  FIG. 12 . 
         [0042]    While the knot  70   a  is dropped by the tier  40  following severance and stripping from the bill hook  82 , the strand  66   b  to source  74 , as well as strand  64   b  to source  72 , is retained by the holder  86 . Consequently, as the needle  42  continues to retract, the strand  66   b  is draped downwardly across the bale chamber  26  while the slack take-up device  154  lowers to its normal position to pull a small amount of additional material from the source  72 . Upon reaching the condition illustrated in  FIG. 13 , the strands  64   b  and  66   b  are in position for institution of the second tying cycle which is started by the finger  118  (which has been previously returned to its standby position) swinging inwardly to engage the strands  64   b  and  66   b  and seat them deeply within the crotch  92  as shown in  FIG. 14 . This assures that the strands  64   b  and  66   b  are properly positioned across and in engagement with the bill hook  82 , whereupon the latter and the holder  86  are operated by their second respective gear stretch  100  and gear section  108  on the element  76 . Thus, the knot becomes formed as illustrated in  FIG. 15 , whereupon the arm  88  is once again actuated, but this time by the second cam shoulder  116 , to sever the knot from the holder  86  and to strip the same from the bill hook  82 . This becomes knot  68   b  in  FIG. 16 , and it will be recognized that such joinder of the strands  64   b  and  66   a  is the start of a new loop which, although not illustrated, would be numbered  62   b.  Such new loop, at its inception, takes the form of an open-ended bight along the lines of, but much shorter than, the partial loop  62   a  in  FIG. 2 . Such bight is in position to receive new material that is packed into the bale chamber  26  by the plunger  30 , and the bight grows in length as additional lengths of the strands  64   b  and  66   b  are simultaneously pulled from their sources  72  and  74 . Finally, when the bale has reached its desired size, the sequence returns to its starting point, whereupon the bight is closed by operation of the needle  42  to complete the loop around the bale and from the second knot. 
         [0043]    As illustrated in  FIG. 2 , and as also shown in  FIG. 16 , two short segments  62 ′ and  64 ′ are released by the holder  86  following completion of the tying sequence and in preparation for start of the next sequence. Such segments are left as a result of the surplus strands that are contained within the discs of the holder  86  following the two cutting strokes of the cutter  94 . 
         [0044]    It should be apparent from the foregoing that two complete tying cycles are carried out during each single revolution of the drive shaft  78 . Thus, each time the needle  42  swings into operation, two knots are formed by the tier  40 . One knot is the second knot  70  on the preceding bale, and the other is the first knot  68  on the next succeeding bale. The cutter  94  operates to sever the two knots from one another, thereby also disconnecting the two bales from each other. 
         [0045]    Of considerable importance is the fact that once the strand  66  is drawn across the bale chamber  26  by the withdrawing needle  42  and the knot  68  is formed, the strands  64  and  66  remain substantially stationary relative to the forming bale throughout the remainder of the bale-forming and knot-tying processes. The additional lengths of binding material required to accommodate growth of the forming bale are readily obtained from the two separate sources of supply  72  and  74 , the resistance to such strand pulling being only that exerted by the sources  72 ,  74  themselves and by any tensioning control units that may be utilized such as the unit  166  in  FIG. 3 . There is no need to pull either strand through the interface formed between the tightly abutting preceding bale and the one being formed, and thus the strands, as well as the tier  40 , avoid the application of excessive tension and stresses. 
         [0046]    The description of the knotter as set out above is similar to U.S. Pat. No. 4,142,746 and the drawings are all essentially the same, save for a modification to the shape of the twine finger  118 , shown in  FIG. 4 . A full description of the operation has been given so that the reader not already familiar with the construction and operation of a double knotter may appreciated the function of the twine finger, the shape of which is modified in the present invention in order to improve the quality of the second knot, as produced in the steps shown in  FIGS. 13 to 16  of the accompanying drawings. 
         [0047]    In the present invention, the edge  118   a  of the twine finger in contact with the runs of twine  64   b,    66   b  as the second knot is being pushed off the bill hook  82  by the crotch  92  has a bump  118   b  which obstructs the runs of twine as they attempt to slide along the edge  118   a  under the action of the crotch  92 . The side of the bump  118   b  which contacts the twine runs is at right angles to the edge  118   a.  The corner between the bump  118   b  and the edge  118   a  catches on the twine runs but does not risk cutting into them. As a result of the obstruction  118   b,  as the crotch  92  is pivoted about the axis  90  to release the knot from the bill hook  82  at the same time as the free ends of the twine are pulled by the bill hook  82  through the loop of twine wrapped around it, the tension in the section of the twine runs between the finger  118  and the bill hook  82  is increased, thus tightening the knot and lengthening the tails protruding from the knot. This increase in tension is achieved without any increase in the tension in the sections of the twine runs drawn from the supply rolls.