SHEARBAR ATTACHMENT AND ADJUSTMENT APPARATUS AND METHOD

Abstract: A shearbar attachment and adjustment apparatus (12) is adapted to apply clamping forces to a shearbar (22) in a forage harvester at first locations on opposite shearbar end portions (42). The clamping forces bend the shearbar (22) in contact with a bowed shearbar support member (20) and prevent the shearbar (22) from backing away from a rotary cutterhead (18) in the forage harvester during chopping of crop material by passing cutting edges (32) of knives (30) on the periphery of the cutterhead (18) close to the cutting edge (64) of the shearbar(22). This bending of the shearbar (22) results in a corresponding convex shape of the shearbar cutting edge (64) which itself, in turn, results in a non-­ uniform clearance between the cutterhead knife path (P) and the shearbar cutting edge (64). The apparatus (12) is also operable to apply adjustment forces on the shearbar (22) at second locations on its opposite end portions (42) which are offset inwardly from the first locations. Application of the adjustment forces at these inward locations relative to the outward locations of the clamping forces tends to compensate for the effect of the convex shape of the shearbar cutting edge (64) by causing deformation of the opposite shearbar end portions (42) toward the cutterhead knife path (P) to provide a more uniform clearance between the cutting edge (64) of the shearbar (22) and the cutting edges (32) of the cutterhead knives (30).

Description: The present invention relates generally to forage harvesters and, more particularly, is concerned with an apparatus and a method for attaching and adjusting the positional relationship of a shearbar relative to a rotary cutterhead of the forage harvester. Reference is hereby made to the copending European patent application 0217.461 (86.201.639) dealing with related subject matter. In a forage harvester, typically, a header delivers crop material from the field in a generally rearward direction to feed rolls which form the crop material into a consolidated mat. The crop material mat is fed rearwardly by the feed rolls over the cutting edge on a stationary shearbar. Cutting edges on a plurality of knives peripherally arranged on a rotating cutterhead pass in close proximity to the shearbar cutting edge to chop the crop material mat into small pieces. For maximum efficiency in the operation of the forage harvester and optimum quality of cut of the crop material, the shearbar should be positioned so that its cutting edge is as close to the passing cutting edges of the cutterhead knives as possible without ticking. An apparatus of some type is typically provided to adjust the position of the shearbar relative to the cutterhead. An adjustment is generally required after each time the cutterhead knives are sharpened. Representative of the prior art are the adjustment apparatuses disclosed in US-A-4.190.209; US-A-4.295.616; US-A-4.436.248; US-A-4.474.336; US-A-­ 4.506.839 and the patent application cross-referenced above. Most desirably, for a uniformly high quality cut and to help keep the cutting edges of the knives in sharp condition, the shearbar-to-knife clearance should be constant throughout. This is difficult to achieve in practice for several reasons. One reason is that most shearbar adjustment apparatuses currently in use, such as those of the above-cited prior art, provide for adjustment of the shearbar by manipulation of components located remote from the shearbar. While providing a more convenient means for the operator to move the shearbar, the adjustment must be carried out without actually observing the shearbar-to-knife clearance. However, a procedure has evolved which alleviates much of the difficulty here. Briefly, the shearbar is moved toward the cutterhead, as the latter is turned slowly, until the knives thereon tick the shearbar lightly. When the knives begin to tick, the shearbar is then backed off from the cutterhead until the ticking stops. The second reason for shearbar adjustment difficulty relates to the way in which the shearbar is commonly supported in the forage harvester. To explain, the shearbar is typically seated and fastened on a support member in such a way that the shearbar will be capable of withstanding the forces encountered during the chopping operation without backing away from the cutterhead. The approach is to ensure that a degree of contact is maintained between the shearbar and the support member along the entire length of the shearbar that is sufficient to create frictional forces therealong capable to countering the chopping force. One known way to provide such degree of contact of the shearbar with the support member is to configure the support member with a convex or crowned upper surface. When the shearbar is then fastened to the support member, the shearbar becomes clamped against the support member and actually bows or bends slightly into an arched shape in seating over the crowned top surface of the support member and thereby provides good contact over the entire length of the shearbar. However, it has been found that, due to the bending, the shearbar-to-cutterhead clearance varies and is less at the middle of the shearbar than at its opposite ends, along the length of the shearbar. This results in reduction of the uniformity of cut and, frequently, of the harvester cutting efficiency. US-A-4.506.839 cited hereabove attempts to overcome the aforementioned negative side effects associated with purposely bending the shearbar in fastening it to the crowned support member by machining a concavity in the cutterhead-facing shearbar surface. The concavity is designed to compensate for the effect of the convexity of the upper shearbar surface by placing the opposite end portions of the cutting edge defined by the intersection of the two nonplanar surfaces closer to the cutterhead and thereby positioning the overall nonlinear cutting edge at a more uniform clearance from the cutterhead. However, this solution appears to have certain significant shortcomings. First, it will surely increase the cost of fabricating the shearbar since machining the concavity introduces additional costly manufacturing steps. Second, the benefits of a permanent concavity will only be realized over an initial short portion of the ordinary useful life of the shearbar. The preformed concavity only reduces the clearance problem initially. Once normal wear to the shearbar distorts the original configuration of the concavity, it can no longer provide the means by which the shearbar can be adjusted to a uniform clearance with the cutterhead. The shearbar attachment arrangement as described above and involving the bending of the shearbar in contact with a bowed support surface often also is combined with a shearbar adjustment arrangement which permits a shearbar-to-cutterhead adjustment without previously loosening the shearbar attachment means. To this end, shearbar adjustment means are provided at the opposite shearbar end portions and which enable to apply adjustment forces on said end portions which are sufficient in magnitude to overcome the resisting frictional forces between the shearbar on the one hand and the shearbar support surface and the shearbar attachment means on the other hand and which thus cause sliding adjustment of the shearbar toward the cutterhead knife path. In the prior art arrangements, these adjustment means are disposed at locations along the opposite shearbar end portions spaced outwardly from the locations where the shearbar attachment means are provided. It has been found that in this arrangement, the adjustment forces cause a bending of the opposite shearbar end portions toward the cutterhead knife path whereby these end portions are positioned closer to the cutterhead knife path than the central shearbar portion. This thus is opposite to the deviation from a uniform shearbar-to-cutterhead clearance induced by the shearbar clamping forces as described earlier. As a matter of fact, the latter deformation greatly exceeds the former and thus the end result is that a non-uniform shearbar-to-cutterhead clearance is obtained with the opposite shearbar end portions being positioned closer to the cutterhead knife path than the central shearbar portion. The same problem as described above, although to a lesser degree, also is inherent to the arrangement according to EP-A-0217.461 to which reference has already been made hereabove. In this arrangement the attachment means and the adjustment means act upon the shearbar at substantially the same locations along the length of the shearbar end portions. In other words, the adjustment forces are applied at locations which are in line with (as seen in the fore-and-aft direction of the machine) or are the same as the locations at wich the clamping forces are applied. An optimum solution for resolving the difficulty of adjusting the shearbar to a uniform clearance from the cutterhead does not appear to reside in any of the adjustment apparatuses of the above-­ cited prior art. Consequently, a need still exists for a different approach to resolving of this difficulty. The present invention provides a shearbar attachment and adjustment apparatus on the one hand and method on the other hand designed to satisfy the aforementioned needs. Adjustment forces are applied to the shearbar at locations on the opposite end portions of the shearbar which are offset inwardly from the locations where the clamping forces are applied. Application of adjustment forces at these inward locations relative to the outward locations of the clamping forces tends to provide a more uniform clearance between the cutting edge of the shearbar and the cutting edges of the cutterhead knives. Unlike the approach taken in US-A-4.506.839, the approach according to the invention facilitates maintainance of a substantially uniform clearance between the shearbar and cutterhead throughout the useful life of the shearbar and does not require a machining of the shearbar to form a concavity therein during the manufacturing thereof. Accordingly, the present invention is directed to a shearbar attachment and adjustment apparatus incorporated in a forage harvester. The forage harvester has a cutterhead assembly including a rotatable cutterhead, an elongated shearbar and said shearbar attachment and adjustment apparatus. The cutterhead has a plurality of knives which, upon rotation, define a knife path and cooperate with a cutting edge of the shearbar for chopping crop material that is fed across said shearbar to said cutterhead. The shearbar attachment and adjustment apparatus comprises a stationary shearbar support member having a convexly bowed support surface and attachment means disposed at opposite end portions of the shearbar for fastening said shearbar upon said support member bowed surface. These attachment means, in fastening the shearbar, apply clamping forces thereto which bend said shearbar into contact with the support member bowed surface to thereby generate frictional forces between the shearbar and the support member. These frictional forces are sufficient to resist any movement of the shearbar induced by the chopping forces imposed thereon during operation on the one hand but yet permit sliding adjustment movement of the shearbar relative to the support member on the other hand. Said clamping forces further also deform the shearbar cutting edge to a convex configuration so that, upon the mounting of the shearbar within the cutterhead assembly in a generally parallel relationship with the cutterhead and upon the subsequent fastening of the attachment means, opposite end portions of the shearbar cutting edge are disposed in a divergent fashion farther from the cutterhead knife path than an intermediate portion of the shearbar cutting edge. Thereby, a non-uniform clearance exists between the shearbar cutting edge and the cutterhead knife path. The shearbar attachment and adjustment apparatus further also comprises adjustment means which are coupled to the opposite shearbar end portions and which are operable to apply adjustment forces on said shearbar which are sufficient in magnitude to overcome the resisting frictional forces and cause said sliding adjustment movement of the shearbar toward the cutterhead knife path. The invention is characterized in that the attachment means are disposed for fastening the shearbar to the support member at first locations along the opposite shearbar end portions and the adjustment means apply adjustment forces on said opposite shearbar end portions at second locations therealong and spaced inwardly from said first locations. The arrangement is such that the adjustment forces cause a deformation of the shearbar concurrently with the adjustment movement thereof in a manner so as to displace the shearbar at said opposite end portions toward said knife path by a greater amount than at the intermediate portion thereof. Thereby a more uniform clearance can be adjustably achieved between the shearbar cutting edge and the knife path. The present invention also relates to a method of attaching and adjusting an elongated shearbar having a cutting edge in a cutterhead assembly of a forage harvester. Said assembly further also comprises a stationary shearbar support member having a bowed support surface and a rotatable cutterhead having a plurality of knives with cutting edges which, upon rotation, of the cutterhead define a knife path passing in close proximity to the shearbar cutting edge for chopping crop material passing over said shearbar. Said method comprises the steps of positioning the shearbar within the cutterhead assembly upon the support member bowed surface in a generally parallel relationship with the cutterhead and applying clamping forces between the shearbar and the shearbar support member generally at the opposite shearbar end portions. Said clamping forces bend the shearbar into contact with the support member bowed surface along the length of said shearbar to thereby generate frictional forces between the shearbar and the support member. Said frictional forces are sufficient to resist any movement of the shearbar induced by the chopping forces imposed thereon during operation on the one hand and yet permit sliding adjustment movement of the shearbar relative to the support member toward and away from the cutterhead for adjusting the position of the shearbar cutting edge relative to the knife path on the other hand. Said clamping forces further also deform the shearbar cutting edge to a convex configuration so that, upon said parallel positioning of the shearbar within the cutterhead assembly and the subsequent applying of said clamping forces, the opposite end portions of the shearbar cutting edge become disposed in a divergent fashion farther from the cutterhead knife path than an intermediate portion of the shearbar cutting edge. Thereby a non-uniform clearance exists between the shearbar cutting edge and the cutterhead knife path. The method further also comprises the step of applying adjustment forces to the shearbar generally at the opposite shearbar end portions. Said adjustment forces are directed generally in the direction toward the cutterhead knife path and are sufficient in magnitude to overcome said resisting frictional forces and cause said sliding adjustment movement of the shearbar toward said cutterhead knife path. This method further is characterized in that the clamping forces and adjustment forces are applied to the shearbar at respectively first and second locations along the opposite shearbar end portions with said second locations being spaced inwardly from said first locations. The arrangement is such that the adjustment forces cause a deformation of the shearbar concurrently with said adjustment movement in a manner so as to displace the shearbar at said opposite end portions toward said knife path by a greater amount than at the intermediate portion thereof. Thereby, a more uniform clearance can be adjustably achieved between the shearbar cutting edge and the knife path. These and other advantages and attainments of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings wherein there is shown and described an illustrative embodiment of the invention. In the course of the following detailed description, reference will be made to the attached drawings in which: Fig. 1 is a side elevational view of a fragmentary portion of a forage harvester cutterhead assembly with which is associated the shearbar attachment and adjustment apparatus of the present invention. Fig. 2 is an enlarged front elevational view, partly in section, of the shearbar attachment and adjustment apparatus at one end of the shearbar, as seen along line 2-2 of Fig. 1. Fig. 3 is a cross-sectional view of a portion of the shearbar attachment and adjustment apparatus taken along line 3-3 of Fig. 1. Fig. 4 is a front elevational view of the shearbar and its support member, illustrating in exaggerated form the upper crowned surface on the support member and the respective solid-line straight and broken-line bowed configurations of the shearbar before and after it is fastened on the upper surface of the support member. Fig. 5 is a schematical top plan view of the shearbar with arrows representing the distribution of frictional forces there along and a graph of the deflection of the shearbar after application of pulling forces thereto in accordance with the principles of the present invention. In the following description, like reference characters designate like or corresponding parts throughout the several views. Also in the following description, it is to be understood that such terms as "forward", "left", "upwardly", etc., are words of convenience and are not to be construed as limiting terms. Referring now to the drawings, and particularly to Fig. 1, there is shown a fragmentary portion of one side of a forage harvester cutterhead assembly, generally designated 10, which incorporates the shearbar attachment and adjustment apparatus 12 of the present invention. As is conventional in a forage harvester, a header (not shown) delivers crop material from a field in a generally rearward direction to and between counter-rotatably driven upper and lower feed rolls 14,16 which form the crop material into a consolidated mat. The crop material mat is fed rearwardly by the feed rolls 14,16 to the cutterhead assembly 10. The cutterhead assembly 10 basically includes a generally cylindrical cutterhead 18, an elongated shearbar support member 20 and an elongated shearbar 22. The cutterhead 18 is rotatably mounted at its opposite ends 24 (only one end being shown) to opposite side sheets 26 (only one being shown) of the forage harvester by bearing assemblies 28. The cutterhead 18 is driven by a suitable conventional drive train (not shown) to rotate about a generally horizontal axis A which extends transverse to the direction of forward travel, as represented by the arrow F in Fig. 1. A plurality of knives 30 having cutting edges 32 are detachably mounted in a peripheral arrangement about the circumference of the cutterhead 18. Both the support member 20 and shearbar 22 of the cutterhead assembly 10 extend between, and project outwardly through openings 34 in, the side sheets 26 at positions generally forwardly of and along the cutterhead 18. As seen in Figs. 1 and 2, inwardly from each of its opposite ends 36 but outwardly of the respective side sheet 26, the support member 20 is rigidly attached by a bolt 38 to a brace 40 affixed to the side sheet. As best shown in Figs. 2 and 3, the shearbar 22 is fastened at each end 42 (only one end being shown) by suitable attachment means, generally indicated by 44, of the shearbar attachment and adjustment apparatus 12 to a corresponding end 36 of the stationary support member 20. Each attachment means 44 takes the form of a clamping bolt 46 which extends through an opening 48 defined through the end of the shearbar 22 and is threaded into an internally threaded vertical bore 50 tapped in the corresponding end 36 of the support member 20. The shearbar opening 48 extends between upper and lower surfaces 52,54 of the shearbar 22 and has a substantially larger diameter than that of the clamping bolt 46. The support member bore 50 opens at an upper surface 56 of the support member 20 for receiving the externally-threaded lower end of the bolt 46. Also, a cylindrical spacer 58 and a stack of precision disc springs 60 encircle the bolt 46 between it upper head 62 and the upper surface 52 of the shearbar 22. The springs 60 act to limit the clamping force which can be applied to the shearbar 22 when the bolt 46 is tightened down on the shearbar. The shearbar 22 has a cutting edge 64 defined by the intersection of its upper surface 52 with a rear surface 66 thereon which faces toward the cutterhead 18 and extends downwardly from the upper surface 52 to the lower surface 54 thereof. (As is well known, another cutting edge may be similarly defined on the opposite longitudinal side of the shearbar for use after the one cutting edge 64 has worn down.) The crop material mat fed rearwardly by the upper and lower feed rolls 14,16 to the cutterhead assembly 10 passes over the upper surface 52 and thus also over the cutting edge 64 of the shearbar 22 before reaching the knives 30 on the cutterhead 18. The cutting edges 32 on the knives 30, being peripherally arranged on the rotating cutterhead 18, pass along a circular path P which brings them into close proximity to the shearbar cutting edge 64 to chop the crop material mat into small pieces. Due to the arrangement of the components of the attachment means 44 as described earlier and the configuration of the support member 20 which will now be described, the shearbar 22 is seated and clamped on the upper surface 56 of the support member 20 in such a way that the shearbar 22 will be capable of withstanding the level of forces normally encountered during the chopping operation without backing away from the cutterhead 18 and its knives 30. Specifically, as shown in exaggerated form in Fig. 4, the upper surface 56 of the support member 20 has a slightly convex or crowned configuration. When the shearbar 22 is then fastened to the support member 20 by the clamping bolts 46, the shearbar 22 becomes clamped against the support member 20 and actually bows or bends slightly into an arched shape in seating over the crowned upper surface 56 of the support member 20 and thereby provides good contact with the support member over the entire length of the shearbar. Thus, a degree of contact is maintained between the shearbar 22 and the support member 20 along the entire length of the shearbar that is sufficient to create frictional forces therealong capable of countering the chopping force. The magnitude and distribution of such frictional forces are schematically represented in Fig. 5 by the arrows pointing downwardly from the shearbar 22. As a consequence of bowing or bending the shearbar 22 to clamp it to the support member 20, its upper surface 52 is thereby deformed from a generally planar to a slightly convex configuration, as seen in dashed outline in Fig. 4. This also deforms the configuration of the cutting edge 64 of the shearbar 22 from generally linear to convex. So now instead of the cutting edge 64 running substantially parallel along the cutterhead 18, it assumes a convex configuration in which its opposite end edge portions are lower than its intermediate edge portion. The opposite end portions of the shearbar cutting edge now diverge away from a generally transverse horizontal line on the cutterhead tangent to the middle of the shearbar edge. This relationship places the opposite end edge portions of the shearbar cutting edge 64 farther away from the cutterhead than the middle or intermediate edge portion which results in the creation of a nonuniform clearance between the cutting edge 64 of the shearbar 22 and the cutting edges 32 of the cutterhead knives 30 as the latter pass through the aforementioned tangent horizontal line on the cutterhead 18. However for maximum efficiency in the operation of the forage harvester and optimum quality of cut of the crop material, the shearbar 22 should be positioned so that its cutting edge 64 is in close noncontacting relation to the passing cutting edges 32 of the cutterhead knives 30 at a substantially uniform distance therefrom from one end of the shearbar cutting edge 64 to the other. Even though the shearbar 22 is clamped along its entire length to the support member 20, the arrangement of the components of the attachment means 44 as described earlier permit sliding movement of the shearbar 22 toward and away from the cutterhead 18 for adjusting the position of the shearbar cutting edge 64 relative to the cutting edges 32 of the cutterhead knives 30. For applying the necessary pulling forces on the opposite ends 42 of the shearbar 22 to slidably adjust it into a generally parallel relationship with the cutterhead 18, the shearbar attachment and adjustment apparatus 12 also includes adjustment means, generally designated 67 and best seen in Figs. 1 and 2. The components of the adjustment means 67 are per se substantially identical to those disclosed in the European patent application cross-referenced above. However, the locations at which the adjustment means 67 applies the necessary pulling forces to the shearbar opposite ends 42 relative to the locations at which the clamping forces are applied thereto by clamping bolts 46 of the attachment means 44 are different. In the cross-referenced application, the pulling forces are applied at locations which are in line with or are the same as the locations at which the clamping forces are applied. It has been experienced that with this alignment of the adjustment and clamping forces, sliding adjustment of the shearbar 22 toward the cutterhead 18 simultaneously also results in a deformation of the shearbar 22 and hence also of the shearbar cutting edge 64 in the plane of adjustment. Indeed, the opposite ends of the shearbar cutting edge 64 are bent relative to the intermediate portion thereof in the direction toward the cutterhead. This deformation thus counteracts the above described problem of non-uniform clearance between the cutting edge 64 of the shearbar 22 and the cutterhead knife path P resulting from the clamping of the shearbar 22 upon the bowed shearbar support 20. However, this further deformation greatly exceeds the amount of divergence of the opposite end portions of the shearbar cutting edge 64 away from the knife path P induced by the clamping forces. Hence, the end result is an overcompensation of the problem caused by the clamping of the shearbar 22 upon the bowed support 20 and thus also the creation of another problem. By coupling the adjustment means 67 to the shearbar 22 to apply the pulling forces on the opposite ends 42 thereof at locations spaced inwardly from the locations of application of the clamping forces, not only is the desired sliding movement of the shearbar 22 toward the cutterhead 18 brought about, but concurrently a deformation of the shearbar 22 and its rear cutterhead-facing surface, as is schematically shown in Fig. 5, is brought about. In practice it has been found that this deformation of the shearbar 22, under the given circumstances, permits that a more uniform clearance can be adjustably achieved between the cutting edge 64 of the shearbar 22 and the cutting edges 32 of the cutterhead knives 30. The adjustment means 67 of the shearbar attachment and adjustment apparatus 12, being located adjacent each side of the cutterhead 18, includes a lever 68 pivotally supported on each respective side sheet 26 about a pivot member 70. The pivot member 70 is supported by a collar 72 connected to the respective side sheet 26 via bracket 74 detachably affixed to the support member 20 by a pair of fasteners 76. The lever 68 is thus pivotally movable in generally a fore-and-aft direction generally parallel to and along the exterior of the side sheet 26. Each respective lever 68 (only one being shown) is coupled to one end 42 of the shearbar 22 at a location spaced inwardly from the location of the clamping bolt 46 by a capscrew 78 extending through an oversized opening 80 in the lever and into threaded engagement with an internally-threaded hole 82 through the shearbar end 42. A pair of cooperable cup and ball washers 84 positioned on opposing sides of the lever 68 give a "ball joint" effect to permit a positional rotation of the lever relative to the corresponding capscrew 78, allowing a generally linear motion of the shearbar 22 and engaged capscrew 78 while the lever 68 is pivoted about its pivot member 70. As best seen in Fig. 1, manipulation of actuation linkage 86 in a known manner from the exterior of the forage harvester causes pivotal movement of the respective lever 68 about its pivot member 70. The relative rotational movement between the cup and ball washers 84, creating the ball joint effect, permits the lever 68 to be rotatably moved about its pivot member 70 and concurrently apply the required pulling force on the capscrew 78 connected to the shearbar end 42 to affect a substantially linear motion of the shearbar 22 between the support member 20 and the spacer 58 on the clamping bolt 46 which goes through the shearbar. As mentioned earlier, due to the location of the capscrew 78 inwardly of the clamping bolt 46, this motion not only permits adjustment of the cutting edge 64 of the shearbar 22 relative to the cutting edges 32 of the revolving knives 30, but also deforms the shearbar 22 in the manner as schematically represented in Fig. 5; this deformation allowing the establishment of a more uniform clearance between the shearbar 22 and cutterhead 18 than was possible heretofore in as much as practice has shown that this deformation very much compensates for the divergence of the opposite ends of the shearbar cutting edge 64 away from the knife path P which is induced by the clamping of the shearbar 22 upon the convexly shaped support member 20. Application of pulling forces at these inwardly offset locations relative to the outward locations of the clamping forces thus tends to compensate for the effect of the convex shape of the shearbar cutting edge 64 and provide a more uniform clearance between it and the cutting edges 32 of the cutterhead knives 30. It is thought that the shearbar attachment and adjustment apparatus of the present invention and many of its attendant advantages will be understood from the foregoing description and it will be apparent that various changes may be made in the form, construction and arrangement of the parts thereof without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefore described being merely a preferred or exemplary embodiment thereof.

Claims: 1. A forage harvester having a cutterhead assembly (10) including a rotatable cutterhead (18), an elongated shearbar (22) and a shearbar attachment and adjustment apparatus (12); said cutterhead (18) having a plurality of knives (30) which, upon rotation, define a knife path (P) and cooperate with a cutting edge (64) of the shearbar (22) for chopping crop material that is fed across said shearbar (22) to said cutterhead (18) and said shearbar attachment and adjustment apparatus (12) comprising : - a stationary shearbar support member (20) having a convexly bowed support surface (56); - attachment means (44) disposed at opposite end portions (42) of the shearbar (22) for fastening said shearbar (22) upon said support member bowed surface (56); said attachment means (44), in fastening the shearbar (22), applying clamping forces thereto which bend said shearbar (22) into contact with the support member bowed surface (56) to thereby generate frictional forces between the shearbar (22) and the support member (20) which are sufficient to resist any movement of the shearbar (22) induced by the chopping forces imposed thereon during operation on the one hand and yet permit sliding adjustment movement of the shearbar (22) relative to the support member (20) on the other hand; said clamping forces further also deforming the shearbar cutting edge (64) to a convex configuration so that, upon the mounting of the shearbar (22) within the cutterhead assembly (10) in a generally parallel relationship with the cutterhead (18) and upon the subsequent fastening of the attachment means (44), opposite end portions of the shearbar cutting edge (64) are disposed in a divergent fashion farther from the cutterhead knife path (P) than an intermediate portion of the shearbar cutting edge (64) whereby, a non-uniform clearance exists between the shearbar cutting edge (64) and the cutterhead knife path (P); and - adjustment means (67) coupled to the opposite shearbar end portions (42) and operable to apply adjustment forces on said shearbar (22) which are sufficient in magnitude to overcome said resisting frictional forces and cause said sliding adjustment movement of the shearbar (22) toward the cutterhead knife path (P); and characterized in that : the attachment means (44) are disposed for fastening the shearbar (22) to the support member (20) at first locations along the opposite shearbar end portions (42) and the adjustment means (67) apply adjustment forces on said opposite shearbar end portions (42) at second locations therealong and spaced inwardly from said first locations; the arrangement being such that the adjustment forces cause a deformation of the shearbar (22) concurrently with said adjustment movement in a manner so as to displace the shearbar (22) at said opposite end portions (42) toward said knife path (P) by a greater amount than at the intermediate portion thereof whereby a more uniform clearance can be adjustably achieved between the shearbar cutting edge (64) and the knife path (P). 2. A forage harvester according to claim 1, characterized in that : - the attachment means (44) and the adjustment means (67) are provided outwardly from the opposite sides of the cutterhead (18); - the convexly bowed support surface (56) of the support member (20) faces upwardly and the cutterhead knives (30) move downwardly as they pass proximate to the shearbar cutting edge (64); and - the shearbar cutting edge (64) is defined by the intersection of a pair of generally orthogonal shearbar surfaces (52, 66); one (52) of which faces generally upwardly and the other (66) of which extends downwardly from said one surface (52) and faces toward said cutterhead knife path (P); said frictional forces between the shearbar (22) and the support members (20) extending generally orthogonal to said cutterhead-facing shearbar surface (66) and being distributed along the length of said shearbar (22). 3. A forage harvester according to claim 2, characterized in that the attachment means (44) comprise : - an opening (48) in each opposite end portion (42) of the shearbar (22) at said first location therealong and which extends between said upwardly-facing surface (52) and a downwardly-facing surface (54) thereof; and - a fastener (46) extending through each of said openings (48) of the shearbar (22) and fastened to the support member (20), said fasteners (46) being adapted to apply said clamping force on the shearbar (22) at said first locations but being smaller in diameter than the openings (48) for permitting movement of the shearbar (22) toward and away from the cutterhead knife path (P). 4. A forage harvester according to claim 3, characterized in that the attachment means (44) comprise at least one spring means (60) mounted on each fastener (46) for limiting the clamping force applied to the shearbar (22) when each said fastener (46) is fastened to the support member (20). 5. A forage harvester according to any one of the preceding claims, characterized in that the adjustment means (67) comprise : - a lever (68) pivotally mounted on a respective side sheet (26) of the cutterhead assembly (10) at a location outwardly of each opposite side of cutterhead (18) and adjacent to each opposite end portion (42) of the shearbar (22); and - interconnecting means (78-84) pivotally mounted to each lever (68) and rigidly connected to the corresponding opposite shearbar end portion (42) at said second location therealong whereby, upon selected pivotal movement of each said lever (68), the respective interconnecting means (78-84) apply said pulling force to said respective shearbar end portion (42) at said second location. 6. A method of attaching and adjusting an elongated shearbar (22) having a cutting edge (64) in a cutterhead assembly (10) of a forage harvester; said assembly (10) further also comprising a stationary shearbar support member (20) having a bowed support surface (56) and a rotatable cutterhead (18) having a plurality of knives (30) with cutting edges (32) which, upon rotation, of the cutterhead (18) define a knife path (P) passing in close proximity to the shearbar cutting edge (64) for chopping crop material passing over said shearbar (22); said method comprising the steps of : - positioning the shearbar (22) within the cutterhead assembly upon the support member bowed surface (56) in a generally parallel relationship with the cutterhead (18); - applying clamping forces between the shearbar (22) and the shearbar support member (20) generally at the opposite shearbar end portions (42); said clamping forces bending the shearbar (22) into contact with the support member bowed surface (56) along the length of said shearbar (22) to thereby generate frictional forces between the shearbar (22) and the support member (20) which are sufficient to resist any movement of the shearbar (22) induced by the chopping forces imposed thereon during operation on the one hand and yet permit sliding adjustment movement of the shearbar (22) relative to the support member (20) toward and away from the cutterhead (18) for adjusting the position of the shearbar cutting edge (64) relative to the knife path (P) on the other hand and said clamping forces further also deforming the shearbar cutting edge (64) to a convex configuration so that, upon said parallel positioning of the shearbar (22) within the cutterhead assembly (10) and the subsequent applying of said clamping forces, the opposite end portions of the shearbar cutting edge (64) become disposed in a divergent fashion farther from the cutterhead knife path (P) than an intermediate portion of the shearbar cutting edge (64) whereby a non-uniform clearance exists between the shearbar cutting edge (64) and the cutterhead knife path (P); and - applying adjustment forces to the shearbar (22) generally at the opposite shearbar end portions (42); said adjustment forces being directed generally in the direction toward the cutterhead knife path (P) and being sufficient in magnitude to overcome said resisting frictional forces and cause said sliding adjustment movement of the shearbar (22) toward said cutterhead knife path (P); and characterized in that : the clamping forces and adjustment forces are applied to the shearbar (22) at respectively first and second locations along the opposite shearbar end portions (42); said second locations being spaced inwardly from said first locations and the arrangement being such that the adjustment forces cause a deformation of the shearbar (22) concurrently with said adjustment movement in a manner so as to displace the shearbar (22) at said opposite end portions (42) toward said knife path (P) by a greater amount than at the intermediate portion thereof whereby, a more uniform clearance can be adjustably achieve between the shearbar cutting edge (64) and the knife path (P). 7. A method according to claim 6, characterized in that the first and second locations along the shearbar end portions (42) are positioned outwardly of the opposite cutterhead assembly side walls (26).

Inventors: MC CLURE, JOHN R., WALDROP, WILLIAM T.
Applicants: FORD NEW HOLLAND, INC. (A DELAWARE CORP.)
Application year: 1988
Main classification: B02C18
IPC codes: B26D7, A01F29