IE50127B1 - Improvements in and relating to rotary mowers and to methods of cutting a crop - Google Patents

Abstract

A rotor for a rotary mower of a kind adapted to cut a crop at two levels has sets of cutting blades (27, 28) with interposed crop deflecting ramps (22) to throw upwardly crop cut by the lower blades (27) above the level of the upper blades (28) to minimise multiple cutting or mincing of the crop. The blades (28) are angularly disposed relative to the blade (27) so as to ensure that at least a major part of a crop is first cut at the upper level.

Description

The present invention relates to rotary mowers of the kind adapted to double cut a crop and to mix lower levels and upper levels of a crop and preferably leave lower levels of the crop on top of upper levels on the ground to thus ensure better drying for the overall crop, and to such methods of cutting a crop.

When preparing a crop for certain purposes and in particular for silage it has been found that there is an advantage in cutting the crop simultaneously at more than one level preferably so that the lower few inches of each stalk is separated from the head of the crop. It is already known to provide a cutting rotor with blades mounted at two different levels. Experience has shown such rotors are normally inefficient, requiring a great deal of additional power for operation. To ensure adequate efficiency of a rotary mower having cutting means in two different planes I believe the crop must be cut as described above but additional cutting of stalks beyond that must be minimised or obviated.

It is therefore an object of the present invention to - 3 provide a cutting rotor for a rotary mower and/or a rotary mower incorporating such a cutting rotor which will go some way to meeting the above mentioned requirements or will at least provide a useful choice over existing rotary mowers.

In one aspect the present invention consists in a cutting rotor for a rotary mower, said cutting rotor comprising a blade carrying body having mounting means to allow for balanced rotational operation of the rotor in the frame of a rotary mower, there being a first cutting blade or blades projecting from the periphery of the blade carrying body, a second cutting blade or blades operating in a locus of rotation above the locus of rotation of said first cutting blade or blades, said first and second cutting blades being angularly displaced one from the other with respect to the rotor axis, and for each second cutting blade a crop deflecting means carried on said blade carrying rotor in advance thereof and following a first cutting blade of the rotor so that crop cut by the said first cutting blade is elevated by the crop deflecting means to clean the second cutting blade or blades.

The rotor may comprise a plurality of sets of first and second cutting blades and crop deflecting means and the angular spacing between the first cutting blade of one set and the second cutting blade of a second set may be less than the angular spacing between the first and second cutting blades of a set to thereby ensure a majority of a crop being cut in use is first cut by a second cutting blade prior to being cut by a first cutting blade.

The number of sets may be two or three.

The blade carrying body may comprise a frustoconical shell with a strengthening disc fitted across towards the base of the said shell.

Each cutting blade may be pivotally carried directly or indirectly by said blade carrying body.

The deflecting means or each deflecting means may define a ramp face capable of providing a vertical component of movement to substantially all of a crop cut by the first cutting blade or blades so that it is upwardly deflected clear of the second cutting blade or blades.

Conveniently, each said second cutting blade is mounted from a ramp face defining deflecting means towards the top of the ramp face.

The present invention includes a rotary mower of the kind as hereinbefore defined wherein a plurality of rotors in accordance with the invention as hereinbefore described are operatively mounted therein. - 5 In a rotary mower of the invention means may be provided to halt the upward deflection of cut crop caused by said crop deflecting means.

Preferably there are provided two cutting rotors operative to rotate in opposition rotational directions so as to provide a windrow in use.

The present invention still further comprehends a method of cutting a crop simultaneously at two levels which involves first mechanically cutting an upper section of at least a majority of the crop at a first upper level and thereafter mechanically cutting a lower section of the same crop at a second lower level in such a way as to throw the lower section of the crop above said first level and allowing the upper and lower sections of the crop to fall to ground without any major proportion of the lower section of the crop being recut by the means for achieving the cut at sai d fi rst level.

Specific embodiments of the invention in its apparatus and method aspects will now be described by way of example, and not by way of limitation, with reference to the accompanying drawings in which: Fig. 1 is a plan view of a rotary mower according to the present invention incorporating cutting rotors of - 6 the present invention, Fig. 2 is a rear elevation of the mower of Fig. 1, Fig. 3 is a plan view of a cutting rotor according to the present invention with two sets of cutting blades, Fig. 4 is a part section in a vertical plane showing the crop deflector and blade carrying body of the rotor, Fig. 5 is a similar plan view to that of Fig. 3 but showing a preferred three set arrangement with the angles alpha and beta showing for a symmetric arrangement as shown the relative angular displacement between a second cutter of a first set and the first cutter of a following or second set, and the angle beta shows the angular displacement between the advancing first cutter and the following second cutter of a particular set, and Fig. 6 is a similar view to that of Fig. 5 but showing a different arrangement whereby angle alpha is increased with respect to angle beta therefore increasing the amount of crop cut initially made by the lower cutter, the arrangement of Fig. 5 being arranged so as to ensure a majority of cutting by the - 7 higher level second cutters.

With reference to the accompanying drawings, a rotary mower has a frame 1 arranged to be supported on a three point linkage assembly tractor. Mounted on the frame are two pulleys 2 and 3 driven by the shaft 4 from the power take off of the tractor. A secondary frame 5 extends from the frame 1 and carries thereon fixed shafts 6 and 7 about which rotate the cutting rotors 8 and 9. The cutting rotors will be described in greater detail hereafter. The shaft 6 has on the bottom end a ground engaging skid 10 and the shaft 7 has on the bottom end a ground engaging skid 11. Each of the rotors 8 and 9 has a pulley fitted to the top thereof and driving belts 12 and 13 pass from the drive pulleys 2 and 3 about the pulleys associated with the rotors 8 and 9 so that the rotors move with a contra direction of rotation as indicated by the arrows on Fig. 1. Belt tightening means 14 are provided as are ground engaging skids 15 and 16. Preferably a guard or shield 17 is mounted in advance of the rotors to assist in moving the crop to a position such that it will be conveniently cut by the rotors and confined after cutting for discharge as a tidy windrow behind the rotary mower. In this respect of course means is thus provided to halt the upward deflection caused By the respective crop deflecting means of that portion of the crop being cut by the lower blade or cutting means of each rotor. - 8 Each rotor 8 and 9 has a frusto-conical shell 18 (see Fig. 4) attached to a central tube 19 through which the shafts 6 or 7 pass in use thus allowing the rotor to revolve about the fixed shaft. Attached to the top of the tube 19 is a pulley 20 about which the belt will pass to drive the rotor. It will be appreciated that each rotor could equally well incorporate a spindle rotatably supported in bearings if desired. The blade carrying body of the rotor is completed by an inner disc 21 towards the base thereof. This construction provides a very strong rotor which forms a stable support for the blades supported thereon. In a normal rotor, cutting blades are supported adjacent the periphery of the blade carrying body and project outwardly therefrom as small pivotal blades there can be two, three or four of these blades mounted about the periphery of the rotor and provided the rotor is in balance the number of blades is not material. With the present arrangement, however, the blades, preferably all of which are pivotally mounted, are arranged in sets and each of two blades of a set is arranged to cut in a different one of two cutting loci, that of the second cutting means or the second cutting blades being above those of the first.

Referring to figures 5 and 6 it can be seen that three blades 27 are equally spaced about the periphery of the blade carrying body and closely preceded by an angular displacement alpha each by a pivotally mounted blade 28 of a different set, such a blade 28 being a second cutting means of that different set. Interposed about the blade carrying body from a first cutting means 27 of one set and the following second cutting means 28 of the same set is a crop deflecting means 22 which will lift that portion of a crop cut by the lower or a lower cutting means 27 to throw the same upwardly above the cutting locus of the following cutter 28 of the same set.

In its present form the deflecting means is a ramp, wedge or the like deflector which gradually increases its ramp angle about the rotor so as to minimise drag. Of course the amount of power required will depend upon the drag and upward component of acceleration to be bestowed on that portion of the crop cut by a first cutter 27 by the following association deflecting means 22.

A person skilled in the art will appreciate with respect to figures 5 and 6 how if the angle alpha is small with respect to angle beta a majority of the crop to be cut will be cut first by an upper locus blade 28 thus throwing the tops of the crop clear of rotor whereupon the almost immediately following lower level cutter 27 will cut the lower level of the crop and gradually, with the assistance of the crop deflector 22 as it spins and advances, lift the same clear of the following blades including the upper level blade 28 of the same set so that the stalks or the 30127 - 10 like fall at least mixed if not on top of a windrow to facilitate drying. Persons will appreciate how for example the arrangement as shown in Fig. 6 would not be highly preferred. Also a person skilled in the art will appreciate that while blades 28 and 27 could well be vertically one above the other the convenience of attaching the upper level blades 28 to the upper extremities of the ramp defining members 22 outweighs any advantage thus derived. Nevertheless it is quite clear that for cutting loci of substantially the same diameter there is likely to be a greater reduction in mincing (i.e. greater than simple dual cutting of a particular plant) as angle beta increases with respect to angle alpha, as on mower advance (if other factors such as crop depression and the like is ignored), the amount of a crop first cut by an upper blade will he proportional to beta and the proportion first cut by a lower blade will be proportional to angle alpha. Also, it will be appreciated that as beta increases (irrespective of number of blades of which there could be just a single set) the steepness and hence the acceleration upwards of a crop cut by a lower blade can be reduced by making the ramp, vane, wedge or the like angle less severe. Referring however to Figs. 1 to 4 showing a two set form of construction, it can be seen that each wedge shaped member 22 has a mounting platform 23 on which the higher level blade is mounted so as to follow the ramp face which commences immediately or preferably some distance after a lower - 11 level cutter.

Preferably the outside edge 24 of the ramp as viewed from above, conforms with the periphery 25 of the rotor and the inner edge 26 forms a shape defined by the boundary of the wedge and the shell 18. The wedge is fixed in place by welding the wedge to the shell along this line. In this respect see Fig. 4. Of course, in other forms of the present invention, means could be provided whereby the wedge and of course also the upper level blades can be removed from the blade carrying rotor.

Indeed, if wished, the wedge could be a hinged member capable, by adjustment, of being raised or lowered.

Preferably, however, having regard to the high forces involved, the wedge member will be welded to the blade carrying body and the first blades will be securely pivotted thereto or to the wedge as the case may be. It is envisaged that should the mower have to be converted to a normal mode of operation, then it is far simpler to provide replacement rotors.

It is envisaged that the cutting edge of each blade will be approximately 2 inches long and that with a two set arrangement substantially as shown it will be possible to rotate the rotors at a speed in the order of 1600 rpm when - 12 the mower is being advanced by a tractor in use at 8 mph.

It can be seen therefore that from the moment a lower level blade makes its cut the angle beta should be sufficient to allow almost 2 inches of advancement into the crop which would butt against the edge 25 prior to an upper level blade making an approximately 2 inch cut thereinto whereupon the cycle would be repeated as many times per revolution as there are sets of blades. Also a person skilled in the art having regard to the speeds involved will appreciate the jamming that could occur if the crop was not cleared by the use of the ramps.

The operation of the mower as described performs a method of cutting a crop such that heavier portions thereof are left on top in a best condition for drying purposes but which nevertheless minimises the amount of mincing and thus power usage.

Claims (16)

1. A cutting rotor for a rotary mower, said cutting rotor comprising a blade carrying body having mounting means to allow for balanced rotational operation of the rotor in the frame of a rotary mower, there being a first

2. A rotor as claimed in claim 1 comprising a plurality of sets of first and second cutting blades and crop deflecting means wherein the angular spacing between the first cutting blade of one set and the second cutting 20 blade of a second set is less than the angular spacing between the first and second cutting blades of a set to thereby ensure a majority of a crop being cut in use is first cut by a second cutting blade prior to heing cut by a first cutting blade. S Ο ί 27 - 14

3. A rotor as claimed in claim 1 or 2 wherein said plurality of sets is two.

4. A rotor as claimed in claim 1 or 2 wherein said plurality of sets is three.

5. Level and allowing the upper and lower sections of the crop to fall to ground without any major proportion of the lower section of the crop being recut by the means for achieving the cut at said first level. 5 to Figs. 1 to 4 or Fig. 5 or Fig.

6. Of the accompanying drawi ngs. 5. A rotor as claimed in any preceding claim wherein 10 each cutting blade is pivotally carried directly or indirectly by said blade carrying body. 5 5. A rotor as claimed in any preceding claim wherein said blade carrying body comprises a frusto conical shell with a strengthening disc fitted across towards the base of said she!1. 5 cutting blade or blades projecting from the periphery of the blade carrying body, a second cutting blade or blades operating in a locus of rotation above the locus of rotation of said first cutting blade or blades, said first and second cutting blades being angularly displaced one

7. A rotor as claimed in any preceding claim wherein said deflecting means or each said deflecting means defines a ramp face capable of providing a vertical component of

8. A rotor as claimed in claim 7 wherein each said second cutting blade is mounted from a ramp face defining 20 deflecting means towards the top of the ramp face.

9. A rotor as claimed in any preceding claim

10. A rotor as claimed in any preceding claim substantially as hereinbefore described with reference 10 from the other with respect to the rotor axis, and for each second cutting blade a crop deflecting means carried on said blade carrying rotor in advance thereof and following a first cutting blade of the rotor so that crop cut by said first cutting blade is elevated by the crop deflecting means

11. A rotary mower of the kind as hereinbefore defined wherein a plurality of rotors as claimed in any preceding claim are operatively mounted therein. 10

12. A rotary mower as claimed in claim 11 including means to halt the upward deflection of cut crop caused by said crop deflecting means.

13. A rotary mower as claimed in claim 11 or 12 having cutting rotors operative to rotate in opposite rotational

14. A mower as claimed in claim 11, 12 or 13 substantially as hereinbefore described with reference to Figs. 1 to 4 or Fig. 5 or Fig. 6 of the accompanying drawings. 20

15. A method of cutting a crop simultaneously at two levels which involves first mechanically cutting an upper - 16 section of at least a majority of the crop at a first upper level and thereafter mechanically cutting a lower section of the same crop at a second lower level in such a way as to throw the lower section of the crop above said first 15 directions so as to provide a windrow in use. - 15 wherein each said crop deflecting means is removably attached to the blade carrying body. 15 movement to substantially all of a crop cut by the first cutting blade or blades so that it is upwardly deflected clear of the second cutting blade or blades. 15 to clear the second cutting blade or blades.

16. A method as claimed in claim 15 when performed 10 using a rotor as claimed in any one of claims 1 to 10 and/or a mower as claimed in claim 12, 13 or 14.