Patent Abstract:
A twine cutting apparatus in combination with an automated grass baler having a twine holding reel for feeding wrapping twine to the baled grass. The apparatus has a pivoted knife arm with a first end structured to cooperate with a cam surface for actuating the knife arm to a cutting position and an opposite end for mounting a twine cutting knife. The twine cutting knife is formed with an elongated, serrated cutting edge extending a distance greater than the radius of the twine holding disc presenting an elongated cutting surface to said twine.

Full Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to hay and grass balers and, in particular, to a twine cutting knife for cutting twine used to wrap bales formed with the balers. 
   2. Description of the Prior Art 
   Ranchers and farmers grow, cut and store grass and hay in rectangular bales to feed livestock during severe winter weather when grass is dormant and livestock cannot graze (round bales may also be gathered using different machinery). This process is performed with a piece of equipment called a square baler, such as, a John Deere 346 Series Baler. A square baler machine, attached to a tractor or similar farm vehicle, gathers and bales fresh cut grass for storage and later use. To keep the bales from falling apart during subsequent handling and storage, the bales are wrapped with twine as they are formed. The twine wrapping and baling operation are synchronized to the amount of grass constituting the size of a finished bale. The baler machine includes a twine spool or reel that feeds twine to and wraps it around the bales, and is then held for tying and cutting in a twine holding disk. After a pre-selected amount of grass or hay is bundled, a twine cutting knife severs the twine allowing the bale to be released from the baler before another bale is formed. Typically the twine knife is mounted on a pivot arm that rotates against the twine holding reel when the twine is cut. 
   Twine used in the baling process is now made with advanced polymer materials that provide great strength to ensure the integrity of the finished bale. However, this type of twine is more difficult to cut. The inability to cut the twine fully and cleanly after completion of a baling cycle creates a wide variety of problems. Usually the worker must get off the tractor and manually sever the twine. This results in wasted twine as well as wasted time. When the twine is not completely cut, the finished bale may not be properly released from the baler and the moving parts of the baler may be subjected to undue strain. This often results in damage to the baler itself, such as jamming the moving parts, causing mechanical breakdown of the baler. 
   Many twine cutters used on conventional square balers use knives not designed to cut the modern twine materials. The twine often merely slides across the edge of the knife and slips off the end without completely cutting the twine, resulting in problems discussed above. Even when the twine is properly cut, the knives wear out relatively quickly when used in conjunction with the advanced polymer twines currently being used within the industry, requiring frequent knife replacement. 
   Prior art blade structures are disclosed in the following patent art. U.S. Pat. No. 2,204,475 to Crandall discloses a knife blade for use with a winding machine. The knife may have either a solid or serrated cutting edge. U.S. Pat. No. 4,995,216 to Vansteelant discloses a bale wrapping control apparatus having a serrated knife. U.S. Pat. No. 5,349,806 to Swearingen et al discloses a wrapping machine for round balers. The twine knife includes a serrated blade that cleanly severs the free end from the twine supply. U.S. Pat. No. 5,709,143 to Bentley discloses a round bale, twine cutter having a steel knife. U.S. Pat. No. 5,878,498 to Mundt discloses a steel tool for cutting bale twine. 
   However, these blade structures are used in very different environments than the knives employed in the use of square balers, such as, the John Deere 346 Series Balers. As the problems encountered are very different, the disclosures are not believed to address the problems currently encountered in the use and operation of square balers. For example, square balers are from time to time, and under certain circumstances, confronted with sap build-up problems not commonly encountered in other types of balers. In addition, the orientation of the various components in square balers is different from other baler types, necessitating different considerations in component design. 
   As such, a need exists for an improved tissue cutting apparatus for a square baler apparatus. The present invention provides such an apparatus. 
   SUMMARY OF THE INVENTION 
   The present invention overcomes the difficulties of the prior art and provides a twine cutting knife for use with square baler machines. The twine cutting knife has a unique structural shape for cutting twine. The shape of the knife is an upright, tapering design having an angled cutting edge with a serrated blade. The serrated cutting edge of the knife provides a structure that creates a positive hold on the twine and improves the cutting action, eliminating any tendency for the twine to slip across the cutting edge surface. Preferably, the knife is made of forged steel for increased strength. The serration and forging virtually eliminates any need for sharpening and maintenance. It is, therefore, an object of the present invention to provide an improved, twine cutting knife for a grass and hay square baler apparatus that ensures twine is completely severed during the twine cutting operation. 
   Another object of the present invention is the provision of a baler twine cutting knife that eliminates baler malfunctions due to improper cutting of bale twine. 
   Still another object of the present invention is the provision of a baler twine cutting knife for use with polymer twines. 
   Yet another object is the provision of a baler twine cutting knife with a serrated cutting edge that eliminates slippage of the twine during a cutting operation. 
   Another object is the provision of a twine cutting knife requiring minimum maintenance and eliminating the need for sharpening. 
   Other objects and advantages of the present invention will become apparent from the following detailed description when viewed in conjunction with the accompanying drawings, which set forth certain embodiments of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a view of a twine cutting knife in accordance with the present invention. 
       FIG. 1   a  shows a detailed view of the cutting edge of  FIG. 1 . 
       FIG. 2  is a schematic view of the twine cutting knife in combination with a twine holding disc. 
       FIGS. 3 to 8  showing the steps associated with knot tying in accordance with use of the present twine cutting knife in a square baler. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The detailed embodiment of the present invention is disclosed herein. It should be understood, however, that the disclosed embodiment is merely exemplary of the invention, which may be embodied in various forms. Therefore, the details disclosed herein are not to be interpreted as limiting, but merely as the basis for the claims and as a basis for teaching one skilled in the art how to make and/or use the invention. 
   The present invention is an improved structure for cutting baling twine associated with a conventional square baler apparatus. Typically, a square baler is attached to a tractor, or similar farm vehicle that drives the baler in a field of cut grass or hay to be baled. The baler gathers and automatically bales the cut grass or hay. As the bales are formed they are wrapped with baling twine to maintain the bale&#39;s integrity for subsequent handling and storage. The baling twine is stored on a supply reel and fed around the baled grass or hay as the baler moves across a field picking up grass or hay. When a pre-selected amount of grass or hay is baled, the twine is cut to complete a bale. The process continues until the baling operation is complete. 
   Such square balers are well known in the prior art and, as such, detailed operation thereof is not disclosed herein in detail. In particular, the present invention is specifically designed for use with square balers, such as, the well known John Deere 346 Series Balers. Other similar balers are disclosed with reference to U.S. Pat. No. 2,926,599, entitled “TYING MECHANISM FOR BALERS AND THE LIKE”, issued Mar. 1, 1960, to McClellan, U.S. Pat. No. 3,101,963, entitled “KNOTTER HOOK FOR BALERS”, issued Aug. 27, 1963, to Sullivan et al., U.S. Pat. No. 4,222,220, entitled “KNOTTER MECHANISM”, issued Sep. 16, 1980, to Nolt et al., and U.S. Pat. No. 4,735,446, entitled “TWINE KNOTTER FOR BALING PRESSES”, issued Apr. 5, 1988, to Homberg, all of which are incorporated herein by reference. 
   With reference to  FIG. 1 , and in accordance with a preferred embodiment of the present invention, the present invention relates to a square baler apparatus for cutting baling twine after a bale is wrapped. As such, the present invention is focused upon a twine cutting knife  10  having an elongated, angled cutting edge  16  with a plurality of serrations  18  on the cutting edge  16 . The serrations  18  include a downwardly directed cutting edge  18   a  shaped and dimensioned for interacting with twine  19  in a manner which optimizes severing thereof, while also providing for an extended useful life when compared to prior art balers. 
   As will be discussed below in greater detail, the use of a serrated cutting edge  16  with downwardly directed cutting edges  18   a  allows the twine cutting knife  10  to grab the twine  19  while it is rotated by the twine holding disk  32 . This provides for efficient cutting without concern that the twine  19  will slide up and over the twine cutting knife  10  during operation thereof. In addition, it has been found that the interaction of the twine  19  with the serrations  18  on the cutting edge  16  provides a continuous cleaning action, removing sap from cut hay that might otherwise hinder operation of the baler as it accumulates upon the twine cutting knife  10 . 
   More particularly, the twine cutting knife  10  is made of forged steel for increased strength and rigidity to withstand the stresses of the cutting operation as the bales are formed. The twine cutting knife  10  is trapezoidal in shape having a lower mounting, or fixed, end  12  and an upper edge or free end  14 . The twine cutting knife  10  includes an elongated, angled cutting edge  16  having a plurality of serrations  18  along its length. Referring to  FIG. 1   a , the serrations  18  include downwardly located cutting edges  18   a  that are generally perpendicular to the longitudinal axis  17  of the twine cutting knife  10  and second cutting edges  18   b  at an oblique angle to the longitudinal axis  17 . The downwardly located cutting edge  18   a  serves to grab and hold the baling twine  19  as it is being cut to ensure the twine  19  does not slip from the twine cutting knife  10  before it is fully cut. The lower end  12  of the twine cutting knife  10  includes mounting holes  20  to facilitate mounting to the knife arm  22 . 
   As briefly mentioned above, the twine cutting knife  10  is designed for use in conjunction with square balers. More particular, and with reference to  FIG. 2 , a baling twine cutting apparatus (for which the present twine cutting knife  10  is constructed) associated with a conventional baler (not shown) includes a C-shaped, knife arm  22  that pivots relative to the baler frame around a central pivot pin  24 . A first end  26  of the knife arm  22  cooperates with a cam arrangement  28  to pivot the knife arm  22  to a twine cutting position. The second end  30  of the knife arm  22  mounts the forged steel twine cutting knife  10  with rivets  24  or other suitable fasteners using the mounting holes  20 . The twine cutting knife  10  is mounted in close proximity to a twine holding disc  32  having a plurality of notches  34  that gather the twine during the wrapping, knotting and cutting operation. The cutting edge  16  of the twine cutting knife  10  extends a distance greater than the radius of the twine holding disc  32  when the twine cutting knife  10  is in a cutting position thereby ensuring the angled cutting edge  16  contacts the twine  19  during the cutting step. 
   When a sufficient amount of grass or hay is gathered and shaped into a bale, the knife arm  22  is rotated, placing the twine cutting knife  10  in contact with the twine  19  as it is grasped by the twine holding disc  32 . The elongated shape of the twine cutting knife  10  and the serrated cutting edge  16  creates a positive hold of the twine  19  and pulls the twine  19  down into a notch  34  on the twine holding disc  32  and cleanly cuts the twine. There is no slippage of the twine  19  during the cutting process, eliminating malfunction of the baler during the cutting process. 
   The effectiveness of the present twine cutting knife  10  will be further appreciated when one considers the tying cycle of a square baler as shown in  FIGS. 3 to 8 . In particular, and with reference to  FIG. 3 , after the needle  40  has been threaded with the twine  19 , the twine  19  is held in the twine holding disk  32  by the twine holder  36 . As the bale  38  is formed within the remainder of the baling apparatus, the twine  19  is pulled from the twine reservoir (not shown). Referring to  FIG. 4 , when the bale  38  reaches its proper length, the measuring wheel (not shown) trips the tying mechanism and the needle  40  brings the second strand of the twine  19  through the guide  42  on the knife arm  22 , across the billhook  44  and into the twine holding disk  32 . Moving now to  FIG. 5 , the billhook  44  starts its revolution when the gear teeth on the intermittent knotter gear have operated the disk driving pinion and turned the twine holding disk  32  sufficiently to permit the twine holder  36  to secure both strands of twine  19  in the twine holding disk  32 . 
   Looking at  FIG. 6 , as the billhook  44  turns clockwise, a loop of twine  19  is formed around the billhook  44  and the jaw  46  opens to receive the twine  19 . The twine cutting knife  10  then advances, ready to cut the twine  19  between the billhook  44  and the twine holding disk  32 . As the twine holding disk  32  continues to rotate in a counterclockwise direction, the twine  19  is brought into contact with the cutting edge  16  of the twine cutting knife  10 . The serrations  18 , in particular, the downwardly located cutting edges  18   a  hooks into the twine  19  forcing the fibers of the twine  19  down and back into the sharp V-shaped edges defined by the downwardly located cutting edge  18   a  and the second cutting edge  18   b . This causes the severing of the twine  19 , ensuring a clean cut each time. 
   It is this action that represents the present twine cutting knife&#39;s advancement over the prior art. By hooking and cutting the twine  19  in this manner, the present twine cutting knife  10  obviates any worries that the twine  19  will slide up and over the twine cutting knife  10  as the twine holding disk  32  rotates in a counterclockwise direction. With this in mind, and considering the fact a preferred embodiment employs a downwardly located cutting edge  18   a  which is generally perpendicular to the longitudinal axis  17  of the twine cutting knife  10 , those skilled in the art will appreciate the downwardly located cutting edge  18   a  may be oriented from approximately perpendicular to the longitudinal axis  17  to a slight downward taper (for example, 5 to 10 degrees downward from perpendicular) while remaining within the spirit of the present invention. 
   Because the twine cutting knife  10  hooks the twine in this manner, prevent sliding toward the upper edge  14  thereof, the length of the cutting edge  16  is not critical to proper functioning of the present twine cutting knife  10 . However, and in accordance with a preferred embodiment, the cutting edge  16  of the twine cutting knife  10  is at least as long as the radius of the twine holding disk  32 . This ensures a sufficient surface for contact between the twine  19  and the twine cutting knife  10 . In addition, the ability of the twine cutting knife  10  to hook the twine enhances the twine cutting knife&#39;s ability to severe the twine  19  and complete calibration of the twine holding disk  32  is, therefore, not critical. 
   At this stage, the needle  40  begins to recede, leaving twine  19  in the twine holding disk  32  which will be held there for the next knot. Referring to  FIG. 7 , the billhook jaw  46  has closed and now holds the ends of the twine  19  tightly. The twine  19  has been cut and the wiper  48  on the knife arm  22  advances to wipe the looped twine  19  from the outside of the billhook  44 , as the jaws  46  hold the two cut ends of twine  19  preparatory to completing the knot. Finally, and as shown in  FIG. 8 , the knot is tied and drops from the billhook  44 , which completes the tie around the bale  38 . 
   While the preferred embodiments have been shown and described, it will be understood that there is no intent to limit the invention by such disclosure, but rather, is intended to cover all modifications and alternate constructions falling within the spirit and scope of the invention.

Technology Classification (CPC): 8