TWINE ARM ASSEMBLY

Abstract: A twine arm assembly (30) for feeding twine into a bale chamber of a large round baler has a first twine arm (40) driven for sweeping its twine dispensing end across the front of the bale chamber and a second twine arm (80) which is pivotally mounted on the first twine arm and which has a twine dispensing end which may be selectively spaced from the end of the first arm (40) by an adjustable spring biased bar assembly (92).

Description: This invention relates to a twine assembly for dispensing twine to wrap a rotating cylindrical bale of crop, having a drivable pair of twine arms pivotally mounted to sweep along the bale in an outgoing and return stroke, each arm having a twine outlet at the outer end thereof from which twine can be drawn in the outgoing stroke to the bale and the arms being coupled so that the outer ends are spaced apart. US-A-4,457,226 shows an automatically actuated and con­ trolled twine wrapping mechanism for a machine producing large cylindrical bales of crop, which employs a single twine arm driven by gearing oscillated by an extensible and retractable hydraulic actuator to cycle a twine dis­ pensing end of the twine arm between opposite sidewalls of the bale forming chamber for causing a bale to be wrapped with spiral wraps of twine. The baler must be stopped dur­ ing the time a bale is being wrapped and consequently it is desirable to shorten the time required for wrapping the bale. The cycle speed of the arm may be adjusted; however, this also adjusts the number of wraps or wrap spacing of twine applied to the bale and such adjustment may not be desirable. Twine wrapping mechanisms employing pairs of gear-driven, twine dispensing arms have been developed for shortening twine wrapping cycle time. These developments are exempli­ fied by the mechanisms disclosed in US-A-4,158,331, US-A-­ 4,167,844 and US-A-4,253,389. One problem with these de­ signs is that they are not applicable for use with balers having relatively narrow bale chambers since a dispensing arm must be relatively long in order for its dispensing end to sweep a relatively shallow arc when dispensing and the space availability for mounting two arms without interfering with one another and with other structure is lacking on a narrow baler. Here again, no way is provided for adjusting the spacing between wraps other than by ad­ justing the cycle speed of the arms. US-A-4,446,783 discloses a twine arm assembly which over­ comes this space problem by mounting two dispenser tubes rigidly on a single support arm. Along the same lines, US-A-4,649,812 proposes a twine arm assembly in which there are two twine arms mounted to swing about a common pivot as does SU-A-1 261 581. However, these assemblies still do not provide means for adjusting the spacing of wraps of twine on the bale without modifying the cycle speed of the arm. The present invention enables the spacing between adjacent wraps to be adjusted without the need to change the cycle speed of the arms. According to the present invention the coupling is adjust­ able for selectively varying the spacing of the outer ends corresponding to a desired spacing on the bale of the wraps of twine derived from one arm from the wraps of twine de­ rived from the other arm. By making the coupling adjustable the spacing of the wraps can be pre-selected without altering the speed of sweep of the arms. An embodiment of the invention will now be described with reference to the accompanying diagrammatic drawings in which: Fig. 1 is a schematic, right side elevational view showing a double twine arm assembly in a rearwardly extending position dispensing twine into the bale forming chamber and showing a portion of a twine cut-off mecha­ nism; Fig. 2 is a front elevational view of the double twine arm assembly showing the double twine arm in a first location from which it moves and to which it returns during a bale wrapping cycle; Fig. 3 is a plan view of the double twine arm as­ sembly shown in Fig. 2 but in addition show­ ing a reversing valve shifter rod and a dashed line second location of the double twine arm reached just prior to operation of the shifter rod; Fig. 4 is a right front perspective view showing the relative positions of the individual twine arms at the time the twine cutting knife operating lever is operated; Fig. 5 is an enlarged, vertical sectional view of the double twine arm taken along line 5-5 of Fig. 4; and Fig. 6 is a plan view of a portion of the double twine arm assembly showing the "piggy-­ backed" twine arm in a middle position of adjustment and indicating other possible adjustment positions. Referring now to Fig. 1, there is shown a lower forward region of a bale forming chamber 10 of a baler for making large cylindrical bales. The chamber 10 is of an expans­ ible type delimited by a plurality of belts supported side­ -by-side on a plurality of rolls extending between a pair of sidewalls forming opposite ends of the chamber and in which the ends of some of the rolls are rotatably mounted with others of the rolls having their opposite ends rotat­ ably mounted in take-up or tensioning arms vertically swingably mounted to the sidewalls. Such an expansible bale chamber is disclosed in detail in US-A-4,428,282. That portion of the chamber 10 illustrated in Fig. 1 in­ cludes a plurality of belts 12 supported in side-by-side relationship across a driven roll 14, a roll 16 located ahead of the roll 14 and about which only selected ones of the belts 12 are trained so as to define a staggered ar­ ray, and a bottom roll 18 which cooperates with the driven roll 14 to delimit a chamber inlet through which crop is fed by a pick-up 22. A driven starter roll 24 is locat­ ed in the inlet 20 for cooperating with the belts 12 for initiating the rolling up of crop to form a bale core about which crop is thereafter rolled to form a complete bale 26, as shown. A double twine arm assembly 30 is shown mounted to a cross beam (not shown) located forwardly of the bale forming chamber 10. Specifically, referring now also to Figs. 2­ 4, and considering the structure as viewed facing in the forward direction of travel, the double twine arm assembly 30 includes a twine arm support 34 fixed to the underside of the cross beam,at a location rightwardly of the fore­ and-aft centre line of the baler, and including right- and left-hand, upright support shafts 36 and 38, respectively, fixed in depending relationship to the beam. A first twine arm 40 is formed of a channel-like main section 42 having an outwardly decreasing taper and having an upright tubular mounting member 44 fixed to an inner end thereof and having a generally horizontal twine dispensing tube 46 fixed to an outer end thereof. A driven gear 48 has a hub welded to an upper end of the member 44 and the member 44 and gear 48 are mounted for oscillation about the right­ hand support shaft 36. A drive gear 50 in the form of a toothed, semicircular sequent has a hub mounted for oscil­ lation about the left-hand support shaft 38. A crank arm 52 projects radially from the hub and carries an upright pin 54 at its outer end. An extensible and retractable hy­ draulic actuator 56 has its rod end connected to the pin 54 through means of a resiliently extensible link 58 and has its cylinder end coupled to the baler frame by a pivot pin 60. The link 58 includes a U-shaped member 62 having its bight portion threadedly received on a threaded end of the actuator rod. A swivel block 64 is pivotally received on the pin 54 and carries a cross pin 66 having opposite ends slidably received in elongate slots 68 provided in opposite legs of the U-shaped member 62. A compression spring 70 is compressed between the bight portion of the member 62 and the block 64 and normally maintains the pin 54 adjacent the ends of the slots 66 remote from the bight portion with the block being against a plate 67 joining the ends of the legs of the member 62. Thus, it will be appreciated that the link 58 will permit further extension of the actuator 56 upon engagement of the crank arm 52 with a stop 72, the purpose of this feature being described in more detail below. A second twine arm 80 is mounted to the twine arm 40 for being moved together therewith by operation of the actua­ tor 56. Specifically, the twine arm 80 includes a channel-­ like section 82 having an outwardly decreasing taper and being located forwardly of the twine arm 40 and carrying a U-shaped bracket 84 adjacent its inner end. The bracket 84 is received between upper and lower flanges of the channel-­ like section 42 of the arm 40 and includes upper and lower legs respectively pivotally connected to the flanges by upper and lower, axially aligned, upright pivot assemblies 86 and 88. A twine-dispensing tube 90 is fixed to an outer end of the twine arm section 82 and is normally held spac­ ed a preselected adjustable distance from the twine-dis­ pensing tube 46 of the first twine arm by a coupling in the form of a spring loaded bar assembly 92, best shown in Figs. 4 and 6. The bar assembly 92 comprises a strap 94 received in an opening 96 provided in the web of the chan­ nel-like section 42 of the first twine arm 40 and secured in place by a bolt assembly 98 secured in the rear end of the strap and a rivet 99 located in the strap on an oppo­ site side of the web from the bolt assembly 98. A coil com­ pression spring 100 is received on the strap 94 and has opposite ends respectively engaged with the respective webs of the twine arms 40 and 80. The strap 94 projects through an opening 104 provided in the web of the channel-­ like section 82 of the second twine arm 80 and a cylindri­ cal spacer 105 is received on the strap and bears against an opposite side of the web from the spring. A plurality of holes 106 is provided along the length of the rod for selectively receiving a retainer in the form of a spring wire clip 107 located ahead of the spacer, as viewed in Fig. 6, for maintaining the arm 80 at a desired disposi­ tion relative to the arm 40 thereby establishing a prese­ lected spacing between the twine dispensing ends of the arms 40 and 80 thereby to establish the spacing of twine strands applied to the circumference of a bale being wrapp­ ed with twine. Thus the spacer 105 and the wire clip 107 together constitute an adjustable abutment for the arm 80. A bolt assembly 108 in the forward end of the strap 94 pre­ vents the arm 80 from accidentally coming off the strap when the clip 107 is removed. The twine arm 40 and the arm 80 carried thereby are mov­ able back and forth in a horizontal plane in front of the bale forming chamber between a first location about nega­ tive fifteen degrees (here shown as the full line position of the twine arms 40 and 80 in Fig. 3 wherein the twine dispensing ends of the arms are adjacent a left-hand side­ wall 110 of the bale chamber) and a second position of about 112 degrees (here shown in dashed lines in Fig. 3 wherein the twine dispensing ends are adjacent a right-­ hand sidewall 111 of the bale chamber). Located adjacent the left-hand sidewall 110 (Fig. 4) is a twine cut-off mechanism 112 including a blade conrol rod 114 having a depending end 116 located for being engaged by an actuator plate 118, fixed to an upper, outer loca­ tion of the twine dispensing tube 46, when the arm 40 re­ turns to its first location. The structure and operation of the twine cut-off mechanism 112 is like that described in the previously identified US-A-4,457,226 and for the sake of brevity is not here described in further detail. A bell crank 120 (Figs. 2 and 3) forming part of a rever­ ser valve control linkage is mounted adjacent the right-­ hand sidewall 111 for rotation about an upright pivot pin 122. A valve shifter rod 124 has one end connected to one arm of the bell crank and has a second end located for en­ gagement by the extendible link 58 upon further extension of the actuator 56 upon engagement of the crank arm 52 with the stop 72, such further extension causing movement of the rod 124 resulting in pivoting of the bell crank and operation of a reverser valve (not shown) coupled for ac­ tuation by movement of the crank arm 52. Such operation of the reverser valve is like that described in the aforemen­ tioned US-A-4,457,226, and for the sake of brevity, is not further disclosed nor described here. Suffice it to say that the actuator 56 will be caused to retract to swing the twine dispensing arms 40 and 80 back to their first location once the reverser valve has been actuated. A stop 126 is positioned to be engaged by the twine dis­ pensing arm 80 as the arm approaches its first location. The spring-loaded bar assembly 92 permits the arm 40 to continue swinging once the arm 80 has engaged the stop 126, the actuator plate 118 then passing above the arm 80 and engaging the blade cotrol rod end 116 to effect actua­ tion of the twine cut-off blade. In operation, the twine wrapping cycle is preferably auto­ matically initiated, in the manner disclosed in the afore­ mentioned US-A-4,457,226, when a bale reaches a predeter­ mined size within the bale forming chamber 10. The twine arms 40 and 80 are then in their first location with their respective twine dispensing tubes 46 and 90 disposed adjacent the left-hand sidewall 110 of the bale forming chamber 10. Initiation of the cycle results in pressure fluid being supplied for exending the hydraulic actuator 56, such extension effecting rotation of the drive and driven gears 50 and 48 respectively and in the arm 40 sweeping toward the rigt-hand sidewall 111, the spring load bar assembly 92 then acting, in tension, to pull the arm 80 behind it. Once respective twine strand ends dangl­ ing from the dispensing tubes 46 and 90 are fed into the bale chamber along with crop fed by the pickup 22, twine will be pulled from respective supply rolls (not shown) and will be fed between the belts 12 and the formed bale. The operation of the pickup 22 is then discontinued with the rotating bale then acting to pull twine from the sup­ ply rolls. Wraps of twine will be spaced on the periphery of the bale in accordance with the setting of the strap 94 determined by the location of the wire clip 107 within the holes 106. When the twine dispensing ends of the arms 40 and 80 near the right-hand sidewall 111 of the chamber 10, the crank arm 52 engages the stop 72. Continued extension of the ac­ tuator 56 is permitted by the compressible link 58, this continued extension being a dwell period in the twine arm cycle permitting additional wraps of twine to be applied to the right-hand end of the bale. The plate 67 at the end of the U-shaped member 62 of the link 58 will act during this further extension of the acutator 56 to engage and displace the reverser valve shifter rod 124 so as to ef­ fect actuation of the reverser valve (not shown) so as to reverse the flow of fluid to and from the actuator 56 to cause it to retract to return the twine arms 40 and 80 to their first location. The arm 80 will lead the arm 40 dur­ ing this return and when the arm 80 reaches its beginning position it will engage the stop 126, the spring-loaded bar assembly 92 then permitting the arm 40 to continue swinging by compressing the spring 100. The actuator plate 118 carried by the arm 40 eventually passes over the arm 80 and engages and shifts the blade control rod 114 to cause actuation of a cut-off blade to sever the twine strands emanating from the tubes of the arms 40 and 80. Wrapping of the bale is then completed and the bale is discharged with operating pressure then being automatical­ ly disconnected from the acutator 56 in the manner describ­ ed in US-A-4,457,226. While the double twine arm assembly 30 has been described herein as being operated by hydraulically driven gears, it will be appreciated that the arm assembly would find uti­ lity with other types of drives as well. Further, while the arm 80 is here shown mounted to the arm 40, it will be appreciated that the arm 80 could be mounted to the sup­ port shaft 36 together with the arm 40 without impairing the operation of the feature of being able to adjust the spacing between the twine dispensing ends of the arms thereby to effect a desired spacing of twine wraps applied to the circumference of a bale.

Claims: 1. A twine arm assembly for dispensing twine to wrap a rotating cylindrical bale of crop, having a drivable pair of twine arms (40, 80) pivotally mounted to sweep along the bale (26) in an outgoing and return stroke, each arm (40, 80) having a twine outlet at the outer end thereof from which twine can be drawn in the outgoing stroke to the bale (26) and the arms (40, 80) being coupled so that the outer ends are spaced apart characterised in that the coupling (92) is adjustable for selectively varying the spacing of the outer ends corresponding to a desired spacing on the bale (26) of the wraps of twine derived from one arm (40, 80) from the wraps of twine derived from the other arm (80, 40). 2. A twine arm assembly according to claim 1 characte­ rised in that the arms (40, 80) are arranged so that twine can be drawn therefrom in the return stroke. 3. A twine arm assembly according to claim 2 in which the assembly includes a blade to sever the twine and in which the arms (40, 80) are drivable via the arm (40) which trails in the return stroke characterised in that the blade is movable to sever the twine by the arm (40) which trails in the return stroke, the assembly includes a stop (126) engageable at the end of the return stroke by the arm (80) which leads in the return stroke, and the coupling (92) includes a yieldable bias (100) normally separating the arms (40, 80) at the selected spacing but being overcome by the trailing arm (40) in the return stroke on en­ gagement of the leading arm (80) with the stop (126). 4. A twine arm assembly according to claim 3 in which the arms (40, 80) are mounted on a common pivot axis (36) characterised in that the leading arm (80) is swingably mounted on the said trailing arm (40) for adjustment of the spacing. 5. A twine arm assembly according to claim 3 or 4 cha­ racterised in that the yieldable bias comprises a coil spring (100). 6. A twine arm assembly according to claim 5 characte­ rised in that the coupling (92) includes a bar (94) secured to one arm (40) and slidably extending through the other arm (80), the coil spring (100) be­ ing located around the bar (94) between the arms (40, 80) to bias them apart, and an abutment (105, 107) for the said other arm (80) adjustably engaged on the bar (94) to stop the arms (40, 80) separating beyond the selected spacing. 7. A twine arm assembly according to claim 6 characte­ rised in that the bar (94) has adjustment holes (106) therein and the abutment comprises a retainer (107) engaged in a said adjustment hole (106). 8. A twine arm assembly according to claim 7 characte­ rised in that the abutment includes a spacer (105) between the retainer (107) and the said other arm (80).

Inventors: WELLMAN, STANLEY PAUL
Applicants: DEERE & COMPANY
Application year: 1988
Main classification: A01F15
IPC codes: A01F15