Harvesters – Cutting – Rotating cutting-reel type
Patent
1989-10-06
1991-07-02
Melius, Terry Lee
Harvesters
Cutting
Rotating cutting-reel type
56291, 56294, 56DIG20, A01D 3453
Patent
active
050275925
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND AND SUMMARY OF THE INVENTION
The present invention relates to a roller-type mower provided with a rotatable drum or roller with surface cutting members, or one continuous helical cutting blade, provided for rotation at a speed required for unrestricted cutting.
Roller-type mowers of the above-described type are used as attachment-type mowers for tractors or as auto-travelling or manually pushed mowers for gardens, golf lawns, fields, or the like.
The known roller-type mowers entail a couple of disadvantages which will be described in the following:
It is commonly known that in mowing devices rotating about a horizontal axis, the percentage of uncut or incompletely cut grass blades increases initially only slightly but later on to a much higher degree as the angle of inclination between the cutting blade and the axis of rotation becomes larger. FIG. 15 illustrates an example of this fact wherein the interrelationship between the cutting energy required for cutting and the angle of inclination .alpha. of the cutter blade is illustrated. A major reduction of the cut quality will arise with a blunt cutting blade at a comparatively small angle of inclination of some 30.degree..
The reason why a helical mower with a slight inclination .alpha. of the helical smooth cutting blade (and thus with a wide angle of inclination) will fail to produce clean cuts is that the helix pushes the stalks to be mowed to the side rather than cutting them.
FIG. 15 moreover illustrates that with the angle of inclination .alpha. increasing, the required cutting energy is first reduced, which means that a dragging cut with lower power consumption will arise.
A mowing helix with a great inclination operates on a smaller angle of inclination .alpha., which may be compared to a beating mower or a beating chopper for field application. Here the beaters hit the stalks approximately at right angles to beat them off. In accordance with the cycloidal mowing path, which is the more cycloidal the higher the travelling speed, the upright stalks are beaten off in comma-shaped sections a.sub.1, a.sub.2 ; . . . (see FIG. 17). The motion of beating the upright stalks from the top to the bottom continues in accordance with the cycloidal paths of the mowing tools, becoming more and more effective, until the stubble height is reached. The stalks are thus cut into multiple pieces over their length, with pieces being so reduced in length that they drop into the stubbles and can no longer be picked up. The multiple severing of the upright stalks also requires an appropriate power supply. When the mowed material is not ejected directly to the rear end, but rather against the stalks still standing, the stalks will also be shortened. Then a stock of mowed material will be formed ahead of the rotor, which the mowing helix partly cuts off and removes even though it increases the volume of the freshly mowed material. The roller-type stock of material ahead of the cutting rotor may also press the fine blades of grass, or beets to be mowed, to such an extent that it will then be seized by the mowing tools only partly. This results in an undesirable stubble height.
In accordance with the foregoing explanation, the power consumption and unfortunately the quality of cut (uniform stubble height) is impaired by a smooth cutting blade with a decreasing inclination of the helix.
With a serrated helix, the inclination of the cutting tooth flank is theoretically decisive for the quality of cut and the power consumption, as well as for the reduction of the natural length of the stalks. The inclination of the helix, however, is relevant also for swath formation, or generally for the axial transport of the mowed material through the mowing helix itself. As can be taken from the laid-open German Patent Application DE 36 35 925 A1, (which corresponds to U.S. Ser. No. 221,255 filed June 22, 1988), the angle of inclination of the mowing helix must not exceed the tangent of the frictional angle of the mowed material (sliding condition).
There is also the particular di
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patent: 3029583 (1962-04-01), Patt
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patent: 4109447 (1978-08-01), Ferguson
patent: 4550554 (1985-11-01), Lundahl et al.
patent: 4719743 (1988-01-01), Bokon
patent: 4920737 (1990-05-01), Wieneke
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