Multistage hammer mill and a residue processing system incorporating same

Abstract

A multistage hammer mill 10 has a plurality of milling stages arranged concentrically so that substantially all material in a first innermost of the milling stages passes through all subsequent adjacent milling stages. A central feed opening 12 enables material flow into a primary impact zone 14 of a first milling stage, which has an impact mechanism 16 and a first screen arrangement 20a. The impact mechanism 16 rotates about a rotation axis 18. The first screen arrangement 20a is disposed circumferentially about and radially spaced from the impact mechanism 16 and has a plurality of apertures 22 through which impacted material of a first size range can pass. A second milling stage has a second arrangement 20b disposed circumferentially about and radially spaced from the first screen arrangement 20a and a circular array of impact elements 50a between the first and second screen arrangements.

1 . A mill for devitalising weed seeds comprising:
 a rotary impact mechanism capable of rotating about a rotation axis, the impact mechanism being arranged to impact material entering the mill and accelerate the impacted material in a radial outward direction, the rotary impact mechanism comprising a plurality of flails, wherein each flail is arranged to pivot about a respective axis that is parallel to the rotation axis;   at least a first circular array of impact elements disposed circumferentially about and radially spaced from the rotary impact mechanism, at least one impact element being elongated and extending in a direction parallel to the rotation axis; and   a base plate to which the rotary impact mechanism and the at least a first circular array of impact elements are attached.   
     
     
         2 . A mill according to  claim 1  wherein comprising a second circular array of impact elements disposed circumferentially about and radially spaced from the first circular array, at least one impact element of the second circular array being elongated and extending in a direction parallel to the rotation axis. 
     
     
         3 . The mill according to  claim 1 , wherein the first circular array of impact elements includes a first ring to which an upper end of each impact element is attached. 
     
     
         4 . The mill according to  claim 2 , wherein the second circular array of impact elements includes a second ring to which an upper end of each impact element is attached. 
     
     
         5 . The mill according to  claim 4  comprising at least one scraper on an upper surface of the second ring. 
     
     
         6 . A mill for devitalising weed seeds comprising:
 a rotary impact mechanism capable of rotating about a rotation axis, the impact mechanism being arranged to impact material entering the mill and accelerate the impacted material in a radial outward direction, the rotary impact mechanism comprising a plurality of flails, wherein each flail is arranged to pivot about a respective axis parallel to the rotation axis; and   at least one stator disposed circumferentially about and radially spaced from the rotary impact mechanism, each stator comprising an upper ring and a lower ring co-axial with each other and surrounding the rotary impact mechanism and a plurality of apertures between the upper and lower rings through which the feed material impacted and accelerated by the rotary impact mechanism can pass.   
     
     
         7 . The mill according to  claim 6  wherein each stator comprises a plurality of ribs that extend in a direction parallel to the rotation axis and between the upper ring and a lower ring, wherein the apertures are located between mutually adjacent ribs. 
     
     
         8 . The mill according to  claim 6  wherein each stator comprises a plurality of gaps dimensioned to enable the passage of impacted material that is too large to otherwise pass through the apertures. 
     
     
         9 . The mill according to  claim 6  wherein the at least one stator comprises two or more stators concentrically arranged about the rotary impact mechanism. 
     
     
         10 . The mill according to  claim 6  wherein the at least one stator comprises a first stator radially closest to the rotary impact mechanism and wherein the mill further comprises at least a first circular array of impact elements disposed circumferentially about the first stator and on a side radially distant from the rotary impact mechanism; the first circular array arranged to rotate about the first stator. 
     
     
         11 . A residue processing system for use in a combine harvester where the combine harvester has: a straw chopper driven to rotate about a first axis; and a power take-off shaft, the residue processing system comprising:
 at least one rotor structure for rotation about a second axis perpendicular to the first axis, the at least one rotor structure having a hub centred on the second axis, a plurality of flails coupled to the hub and a first array of impact elements disposed circumferentially about the hub, and   a drive system for transferring drive derived from the power take off shaft to the at least one rotor structure to cause the at least one rotor structure to rotate about the second axis.   
     
     
         12 . The residue processing system according to  claim 11  wherein the at least one rotor structure comprises two rotor structures mounted on the combine harvester and disposed side-by-side. 
     
     
         13 . The residue processing system according to  claim 11  wherein the drive system includes a plurality of pulleys and belts arranged to transfer drive derived from the power take-off shaft to the rotor structures. 
     
     
         14 . The residue processing system according to  claim 11  wherein the first axis about which the chopper rotates about is parallel to a power take off shaft. 
     
     
         15 . The residue processing system according to  claim 14  wherein the drive system includes a gear box coupled between the power take off shaft and the at least one rotor structures, the gear box having an input shaft and an output shaft wherein the input shaft is able to rotate about an axis parallel to power take off shaft and the output shaft is able to rotate about an axis parallel to the second axis. 
     
     
         16 . A combine harvester comprising:
 a straw chopper for chopping straw produced by the combine harvester when harvesting a crop; and   a residue processing system for processing residue, which includes weed seeds, generated by the combine harvester when harvesting the crop, the residue processing system comprising: at least one rotor structure having a plurality of flails arranged to rotate about a first axis to impact the residue and accelerate the impacted residue in a radial outward direction; an outlet; and one or more stators disposed about the flails, the one or more stators provided with apertures; wherein the residue impacted and accelerated by the rotor structure is able to pass through the apertures and flow to and out of the outlet.   
     
     
         17 . The combine harvester according to  claim 16  wherein the outlet is arranged to direct residue processed by the residue processing system into the chopper. 
     
     
         18 . The combine harvester according to  claim 17  wherein the combine harvester has a tailboard, and the outlet is arranged to direct residue processed by the residue processing system onto the tailboard. 
     
     
         19 . The combine harvester according to  claim 16  wherein the residue processing system comprises two rotor structures, the rotor structures located side by side. 
     
     
         20 . The combine harvester according to  claim 16  wherein each rotor structure comprises at least one array of impact element disposed circumferentially about and radially spaced from the flails wherein the flails and the at least one array of impact elements are rotated together about the first axis.