High speed sickle cutting system

Harvesters – Cutting – Cutter members

Reexamination Certificate

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C059S060000, C059S060000, C059S060000

Reexamination Certificate




1. Field of the Invention
The present invention relates to sickle bar mowers and crop-harvesting machine systems and more particularly, to a new cutting system designed and proven to improve cutting efficiency, speed, and quality. The new cutting system utilizes knife sections spaced less than three inches apart which reciprocate at approximately 2475 strokes per minute. The present invention provides a superior cutting efficiency and a higher maximum effective speed as compared to the sickle bar mower or crop harvesting machine of the prior art.
2. Description of the Related Art
The standard or conventional sickle bar mower or crop-harvesting machine provides a sickle bar cutting system which further consists of a sickle with three-inch wide knife sections. The knife sections are placed adjacent to one another and three inches apart, as measured from one knife tip to the next, on a reciprocating sickle bar. Two-prong sickle guards are mounted to a stationary support bar located adjacent to the reciprocating sickle bar of the system. Stationary knife hold-down clips are also provided on the support bar. A driving mechanism that provides a three-inch reciprocating motion to the reciprocating sickle bar is also provided. Typically, the driving mechanism moves the sickle bar in a reciprocating motion at a speed of approximately 1,650 strokes per minute. Each knife section attached to the sickle bar moves between the stationary sickle guards which are overlaying the adjacent sickle bar and knife sections. The movement of the knife sections within overlaying sickle guards creates a shearing action. The sickle guards provide the base for the shearing action and also support and protect the sickle bar and knife sections as the sickle bar strokes.
The standard knife velocity averages approximately 4.7 miles per hour and the maximum knife velocity is approximately 7.5 miles per hour. However, the standard sickle cutting system allows mowers, crop-harvesting machines, and the like to operate effectively at a maximum ground speed of approximately 4.5 to 5 miles per hour. The standard system can increase its maximum ground speed to approximately 8 miles per hour. However, the standard system cannot operate effectively at such a speed.
The sickle may be driven through a pitman rod attached to the sickle head by means of a ball-and-socket joint. Alternatively, a wobble-joint drive or hydraulic or pneumatic reciprocation means may be used to transform rotary motion to reciprocating motion in order to drive the sickle.
The standard sickle cutting system has limitations. The three-inch stroke between sickle guards limits the travel speed of the machine. That is, if the ground speed of the cutting system exceeds the speed of the blade's reciprocation, crops being harvested will be pushed forward to a large degree before they are cut. This is due to the an accumulation of crop material between sickle guards which is occurring at a rate faster than the rate of cutting. From one sickle guard, the knife sections of the standard sickle cutting system must travel a distance of three inches before reaching an adjacent sickle guard and cutting crop material there against. Therefore, where the typical cutting system is operated at sufficiently high speeds, the end result is an accumulation of crop material between sickle guards prior to cutting which further results in a mashing and shattering the grain heads. Thus a significant portion of the crop may be lost when harvesting grains at sufficiently high speeds with the typical cutting system of the prior art.
Attempts have been made to improve the current sickle cutting system. U.S. Pat. No. 4,651,511 to Majkrzak employs a modified sickle guard system. The sickle guards come in two forms, long and short. The sickle guard fingers alternate between the long and the short variety on the sickle bar. The long sickle guard fingers, sized akin to other guard fingers of the prior art, are spaced three inches apart from one another while the shorter guard fingers are spaced there between. This leaves approximately one and one half inches of space between the short and long alternating sickle guards. While this does reduce the travel distance necessary for a knife section to cut crop material against adjacent guards, the one and a half inch spacing tends to reduce cutting effectiveness. Again, the rate of reciprocation and the short guard fingers fail to prevent crop accumulation. As a result crop stems continue to accumulate and are pushed forward to a large degree before cutting occurs. Additionally, plugging problems occur with heavy, dense, or vineal material such as large weeds or corn stalks.
The present invention is a new sickle cutting system that enables mowers, crop harvesters, and the like to cut hay, grain, and other crops more efficiently with respect to time and production. The invention provides a considerable reduction in grain loss. Stems are cut more cleanly rather than in aggregate which lessens shock to the crop. Further, if any shattering of grains does occur, the grains are likely to fall onto the combine head due to a higher possible ground speed of the cutting system.
The present invention is an improvement in sickle bar mower cutting systems of the types used in agricultural harvesting and mowing equipment. Ideally, this unique system comprises a sickle having knife sections uniformly spaced approximately two-inches from one another, as measured from their tips, on a knifeback bar. The knife sections may be smooth or serrated. A plurality of knife guards have sickle guard fingers thereon which are spaced at approximately two-inches from one another and match the spacing of the knife sections. The knife sections and guard fingers may be of any number. The knife guards are mounted to the support bar of a mower, crop harvesting machine, or the like. The sickle guard fingers of the knife guards provide a cutting surface for the sickle during its horizontal reciprocation. Adjustable hold-down clips enclose the knife sections within guard fingers and against the cutting surfaces thereof. The clips also provide a rear wear bar for the knifeback bar. Ideally, the high speed sickle system has, but is not limited to, a two-inch stroke driving mechanism that coverts rotary motion to reciprocating motion and drives the sickle at a speed of approximately 2475±10% stokes per minute (spm). The drive mechanism may be a wobble box, a pitman type, or other device including hydraulic and pneumatic reciprocating mechanisms that would provide the specified length and speed of stroke.
With a two-inch stroke ±10% and a speed of 2475±10% spm, this unique sickle cutting system has the same knife lateral speed as the standard three-inch sickle system. The knife sections travel two inches in one direction and cut the crops against a guard finger and then travel back and cut the crops against the adjacent guard finger. Rather than traveling three inches in one direction to cut crops against a guard finger, the knife sections need only travel a maximum of two inches. This enables mowers, crop harvesting machines, and the like to travel forward at a ground speed approximately 50% faster than standard systems while at the same time reducing crop stem accumulation by approximately 33%. It also results in more uniform, easier, and more efficient crop cutting. Further, the two-inch spacing allows a three-prong guard to fit existing standard cutter bars utilizing three inch spacing without modification thereof. That is, the standard guard having two fingers is simply replaced with a guard having three fingers.
This newly-designed, high-speed sickle cutting system has been tested under field conditions with different field crops and may be adapted to all known uses of sickle bar mowers used for cutting field crops and harvesting grain.
Table 1 shows the primary technical features of the high-speed sickle cutting system and a comparison to the standard or conventional three-inch sickle system.


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