Patent Publication Number: US-2023142637-A1

Title: Chopping Blade of a Forage Harvester and Method for Producing Said Chopping Blade

Description:
The invention relates to a chopping blade of a forage harvester. Furthermore, the invention relates to a method for producing a chopping blade of a forage harvester. 
     EP 3 329 765 A1 discloses a chopping blade of a forage harvester, having a basic body and having at least one crop-guiding element fastened to the basic body. The basic body has a fastening portion for fastening the chopping blade to a chopping drum and a cutting portion which is angled in relation to the fastening portion and is intended for the harvested crop to be chopped. The respective crop-guiding element is fastened to the fastening portion of the basic body and serves for guiding chopped harvested crop. A guide surface of the crop-guiding element has a curved contour. The curved contour of the crop-guiding element begins at a distance from a transition edge between the fastening portion and the cutting portion of the basic body. The chopping blade which is known from EP 3 329 765 A1 is designed in respect of fastening of same to the chopping drum. This gives rise to problems in the guiding of the chopped harvested crop. There is a need for a chopping blade which optimally conducts or guides the chopped harvested crop. 
     Taking this as the starting point, the present invention is based on the object of providing a novel chopping blade of a forage harvester and a method for producing the chopping blade. 
     This object is achieved by a chopping blade of a forage harvester according to claim  1 . 
     According to the invention, the distance between the beginning of the guide surface of the respective crop-guiding element and the transition edge between the fastening portion and the cutting portion of the basic body is between 4 mm and 8 mm. 
     The guide surface of the respective crop-guiding element runs, according to the invention, rectilinearly with a length between 4 mm and 8 mm in a first portion of the crop-guiding element, which portion adjoins the beginning of the guide surface, wherein the first portion of the respective crop-guiding element encloses an angle between 18° and 22° with the fastening portion of the basic body. 
     The first portion of the respective crop-guiding element merges, according to the invention, into a concavely curved second portion, the radius of curvature of which is between 21 mm and 25 mm and which has a wrap angle between 29° and 33°. 
     The second portion of the respective crop-guiding element merges, according to the invention, in a concavely curved third portion, the radius of curvature of which is between 18 mm and 22 mm and which has a wrap angle between 24° and 28°. 
     The third portion of the respective crop-guiding element merges, according to the invention, into a convexly curved fourth portion. 
     A maximum height of the respective crop-guiding element with respect to the fastening portion of the basic body is, according to the invention, between 24 mm and 30 mm. The fourth portion of the crop-guiding element preferably merges into a fifth portion which defines the maximum height of the crop-guiding element. 
     The distance between the beginning of the guide surface of the respective crop-guiding element and the transition edge of the basic body, the length of the first portion of the guide surface of the respective crop-guiding element, the radii of curvature and wrap angles of the concavely curved second and third portions of the guide surface of the respective crop-guiding element, the convexly curved fourth portion and the height of the respective crop-guiding element, as measured from the fastening portion of the basic body, in combination with one another permit optimum guidance of the chopped harvested crop. The optimum guidance and deflection of the chopped harvested crop makes it possible to save on energy in the conveying process since the deflection of the chopped harvested crop is associated with little acceleration work. 
     Furthermore, by means of the above combination of features, the harvested crop is deflected in a defined region of one revolution of the chopping drum, thus reducing the circulation of the harvested crop in the region of the chopping drum. 
     Accordingly, the above combination of features is optimized in terms of flow and reduces the energy requirement necessary for the flow of harvested crop. The harvested crop is conveyed with a high degree of efficiency for a wide variety of harvested crops, cut length and throughput rates. 
     The fourth portion of the respective crop-guiding element preferably has a radius of curvature between 5 mm and 7 mm, wherein the fifth portion of the respective crop-guiding element runs parallel to the fastening portion. This serves for further optimizing the guidance of the harvested crop. 
     The fifth portion of the respective crop-guiding element preferably merges into a rectilinearly running sixth portion which encloses an angle between 23° and 27° with the fastening portion. The guidance of the harvested crop can thereby also be further optimized. 
     The respective crop-guiding element is preferably closed by portions adjoining the sixth portion. This advantageously prevents harvested crop from accumulating on the trailing blade edge. Accumulations may lead to an imbalance. This feature therefore also serves for further optimizing the guidance of the harvested crop. 
     The respective crop-guiding element is preferably a roll profiling element. During roll profiling, surfaces are hardened, thus making it possible to provide increased hardness for the respective crop-guiding element. The susceptibility of same to wear can thereby be reduced. 
     The first portion, the second portion and the third portion of the respective crop-guiding element preferably bear a wear-protection coating. The susceptibility of the respective crop-guiding element to wear can thereby also be reduced. 
     The method for producing the chopping blade is defined in claim  12 . 
    
    
     
       Preferred developments of the invention emerge from the dependent claims and the description below. Exemplary embodiments of the invention, without being restricted thereto, will be explained in more detail with reference to the drawing, in which: 
         FIG.  1    shows a cross section through a chopping blade according to the invention; 
         FIG.  2    shows the cross section of  FIG.  1    together with geometrical sizes; 
         FIG.  3    shows a detail from  FIG.  2   ; 
         FIG.  4    shows the detail of  FIG.  3    together with crop flow arrows; 
         FIG.  5    shows the detail of  FIG.  3    together with further crop flow arrows; 
         FIG.  6    shows the detail of  FIG.  3    together with further crop flow arrows; 
         FIG.  7    shows the detail of  FIG.  3    together with further crop flow arrows; 
         FIG.  8    shows a further detail from  FIG.  2   ; and 
         FIG.  9    shows a further detail from  FIG.  2   . 
     
    
    
       FIG.  1    shows a cross section through a chopping blade  10  according to the invention. The chopping blade  10  according to the invention has a basic body  11  and at least on crop-guiding element  15 . 
     The basic body  11  of the chopping blade  10  has a fastening portion  12  for fastening the chopping blade  10  to a chopping drum, not shown, and a cutting portion  13  which is angled in relation to the fastening portion  12  and is intended for cutting the harvested crop to be chopped. 
     The cutting portion  13  of the basic body  11  of the chopping blade  10  is angled in relation to the fastening portion  12  of the basic body  11 . 
     A transition edge  14  in the form of a bending edge is formed between the fastening portion  12  and the cutting portion  13  of the basic body  11  of the chopping blade  10 . 
     As already explained, the chopping blade  10  is fastenable to a chopping drum, not shown, via the fastening portion  12 . For this purpose, the fastening portion  12  is provided with fastening elements which are not shown, are preferably in the form of elongated holes and via which the chopping blade  10 , specifically the basic body  11  thereof, can be fastened to the chopping drum. 
     At least one crop-guiding element  15  is fastened to the fastening portion  12  of the basic body  11 . The crop-guiding element  15  has a guide surface  16  for chopped harvested crop, the guide surface  16  having a curved contour at least in sections. The guide surface  16  is curved concavely inward here in section. 
     The guide surface  16  of the crop-guiding element  15  has a front edge  17  at which the guide surface  16  begins. This edge  17  of the guide surface  16  of the crop-guiding element  15  is at a distance a from the transition edge  14  between the fastening portion  12  and the cutting portion  13  of the basic body  11 . 
     According to the invention, the distance a between the beginning of the guide surface  16  of the crop-guiding element  15 , i.e. the edge  17 , and the transition edge  14  between the fastening portion  12  and the cutting portion  13  of the basic body  11  is between 4 mm and 8 mm, i.e. 6 mm±2 mm. 
     The guide surface  16  of the crop-guiding element  15  runs rectilinearly, according to the invention, in a first portion  18  adjoining the edge  17 , specifically along a length b which is between 4 mm and 8 mm, i.e. 6 mm±2 mm. Said first portion  18  of the crop-guiding element  15  encloses an angle α between 18° and 22°, i.e. 20°±2°, with the fastening portion  12  of the basic body  11 . 
     Said first portion  18  of the guide surface  16  of the crop-guiding element  15  merges, according to the invention, into a concavely curved second portion  19 , specifically continuously and thus tangentially, the second portion  19  having a radius of curvature Rx between 21 mm and 25 mm, i.e. 23 mm±2 mm, and a wrap angle β between 29° and 33°, i.e. 31°±2°. 
     Said second portion  19  of the guide surface  16  of the crop-guiding element  15  merges, according to the invention, into a concavely curved third portion  20 , specifically again continuously or tangentially, the concavely curved third portion  20  having a radius of curvature Ry between 18 mm and 22 mm, i.e. 20 mm±2, and a wrap angle γ between 24° and 28°, i.e. 26°±2°. 
     The radius of curvature Rx of the concavely curved second portion  19  of the guide surface  16  of the crop-guiding element  15  is greater than the radius of curvature Ry of the concavely curved third portion  20  of the guide surface  16  of the crop-guiding element. 
     Furthermore, the wrap angle β of the concavely curved second portion  19  is greater than the wrap angle γ of the concavely curved third portion  20 . 
     The concavely curved third portion  20  of the guide surface  16  of the crop-guiding element  15  merges, according to the invention, into a convexly curved fourth portion  21 , said fourth portion  21  of the crop-guiding element  15  preferably merging into a fifth portion  22  which preferably determines the maximum height c of the crop-guiding element  15 , as measured from the fastening portion  12  of the basic body  11 . 
     Said maximum height c of the crop-guiding element  15  is, according to the invention, between 24 mm and 30 mm, i.e. 27 mm±3 mm. 
     The above parameters of the chopping blade  10  permit an optimum guidance of the harvested crop flow. The harvested crop is guided with little acceleration work, thus making it possible to save on energy for the conveying process. The circulation of the harvested crop, i.e. the time during which the harvested crop is guided on the chopping blade  10  in the region of the respective crop-guiding element  15  and therefore within the chopping drum, can be reduced. The guidance of the harvested crop can be undertaken in an ideal way for a wide variety of harvested crops, cut lengths and throughput rates by means of the above geometrical sizes. 
     The fourth portion  21  of the crop flow element  15  preferably has a radius of curvature Rz between 5 mm and 7 mm, i.e. 6 mm±1 mm. This also serves for the optimum guidance of the harvested crop. 
     The fifth portion  22  of the crop-guiding element  15  merges, preferably continuously or tangentially, into a rectilinearly running sixth portion  23 , said sixth portion  23  enclosing an angle δ between 23° and 27°, i.e. 25°±2°, with the fastening portion  12  of the basic body  11 . This is also of advantage in respect of optimum guidance of the harvested crop. 
     The crop-guiding element  15  is designed to be closed by means of portions  24 ,  25  and  26  adjoining the sixth portion  23 . The sixth portion  23  of the crop-guiding element  15  thus merges into a convexly curved seventh portion  24  and the seventh portion  24  into a rectilinearly running eighth portion  25  which is adjacent to the fastening portion  12  of the basic body  11  and via which the respective crop-guiding element  15  is preferably connected to the fastening portion  12  of the basic body  11 . 
     Said eighth portion  25  merges into a ninth portion  26  which, at its end facing away from the eighth portion  25 , makes contact with the second portion  19  of the guide surface  16  of the crop-guiding element  15 . 
     The ninth portion  26  and the second portion  19  of the crop-guiding element  15  are interconnected in an integrally bonded manner here preferably by means of welding. Said welded connection is preferably formed by laser welding. 
       FIG.  4    visualizes, with reference to the arrows  27 , the advantageous effect of the size of the distance a between the edge  17  of the guide surface  16  of the crop-guiding element  15  and the transition edge  14  of the basic body  11  for guiding the harvested crop. The chopped harvested crop is first deflected in the transition region between the cutting portion  13  and the fastening portion  12  of the basic body  11 . This is of advantage both in respect of the guidance of the harvested crop and in respect of a reduction in wear. 
     Even in the event of a worn cutting portion  13  and longer cut lengths, the chopped harvested crop does not strike against the crop flow element  15 . The distance a is selected here in such a manner that the chopped harvested crop is not conveyed too far into what is referred to as a turning circle of the chopping drum. 
       FIG.  5    visualizes, by way of an arrow  28 , the guidance of the cut harvested crop at the transition into the first portion  18  of the guide surface  16  of the crop-guiding element  15 . The relatively shallow angle α causes a further deflection of the cut harvested crop onto the crop flow element  15 , wherein, according to  FIG.  6   , the harvested crop subsequently passes in the direction of the arrow  29  into the second portion  19  of the guide surface  16  of the crop-guiding element  15 . The concavely curved portion  19  causes a further deflection of the chopped harvested crop in the direction of rotation DR of the chopping drum, with the chopped crop-guiding element  15  accelerating the harvested crop in the direction of rotation DR of the chopping drum. 
     Subsequently, according to  FIG.  7   , the chopped harvested crop first of all passes in the direction of the arrows  30  and  31  into the third portion  20  of the guide surface  16  of the crop-guiding element  15 , with the cut harvested crop being further deflected in the direction of rotation DR by means of the reduced radius Ry of the third portion  20 . In the direction of the arrow  31 , the chopped harvested crop leaves the drum turning circle owing to the rotational acceleration because of the centrifugal force. 
     The radius Rz of the fourth portion  21  extends in the opposite direction and prevents residues of the chopped harvested crop from accumulating in this region. 
     The crop-guiding element  15  prevents the chopped harvested crop from penetrating on the inner side of the chopping blade  10  too great a distance into the drum turning circle. This would lead to a delayed discharging of the harvested crop and thus to an extended circulation of the harvested crop. It is possible to prevent the harvested crop from rotating within the drum housing. Finally, the transport of the harvested crop is configured such that it can be undertaken efficiently with little requirement for energy. 
     The crop-guiding element  15  is preferably designed as a roll profiling element. 
     During roll profiling, a blank sheet for the crop-guiding element  15  is deformed and the surface thereof hardened. As a result, the crop-guiding element  15  has increased hardness and a low susceptibility to wear. 
     According to an advantageous development, the crop-guiding element  15  has a wear-protection coating at least on the first portion  18 , second portion  19  and third portion  20 . Such a wear-protection coating is preferably composed of a tungsten-carbide alloy which can be applied via laser powder build-up welding. The susceptibility of the crop-guiding element  15  to wear can thereby be further reduced. 
     The invention furthermore relates to a method for producing the above-described chopping blade  10 . During the production of the chopping blade  10 , first of all the basic body  11  which has the fastening portion  12  and the cutting portion  13 , which is angled in relation to the fastening portion  12 , is provided. This can be undertaken by the cutting portion  13  being bent over in relation to the fastening portion  12 . Furthermore, at least one crop-guiding element  15  which is connected to the basic body  11  is provided. The crop-guiding element  15  is preferably deformed by roll profiling of a sheet metal blank made of steel and brought into the above-described contour consisting of the nine portions  18  to  26 . The first portion  18 , the second portion  19  and the third portion  20  of the crop-guiding element  15  are preferably coated here with a wear-protection coating, preferably with a tungsten-carbide alloy. The ninth portion  26  is preferably welded to the second portion  19 . 
     LIST OF REFERENCE SIGNS 
     
         
           10  Chopping blade 
           11  Basic body 
           12  Fastening portion 
           13  Cutting portion 
           14  Transition edge 
           15  Crop-guiding element 
           16  Guide surface 
           17  Edge 
           18  first portion 
           19  second portion 
           20  third portion 
           21  fourth portion 
           22  fifth portion 
           23  sixth portion 
           24  seventh portion 
           25  eighth portion 
           26  ninth portion 
           27  Harvested crop guide 
           28  Harvested crop guide 
           29  Harvested crop guide 
           30  Harvested crop guide 
           31  Harvested crop guide