Patent Application
20170079203
The present invention refers to a cutter bar applicable to motor mowers or to movers of any type.
In particular, the present invention refers to a cutter bar configured to make a scissor cut with double reciprocating motion of the lower and upper blades.
As can be worked out, the type of mower bars with reciprocating motion, also called “sickle bars”, presupposes the presence of two elements, at least one of which is a cutter, which move with reciprocating motion with respect to one another.
Substantially, the cutting can be obtained in two different ways, i.e.:
The bars configured to carry out a contrast cut with the aforementioned toothed comb cut the grass by “shearing” effect, or indeed by contrast, i.e. the blade of grass rests on one side on the edge of the tooth and is cut by the blade.
With this way of cutting it is not necessary for there to be pressure between blade and underlying tooth and therefore such bars require less accurate adjustment of the cutting elements.
On the other hand, these bars configured to carry out a contrast cut do not always ensure good reliability.
Indeed, with this type of bars, for example in conditions of already cut grass, flattened or tangled due to rain and wind, the teeth of the comb find it difficult to penetrate into the grass to be cut, which instead is pushed forwards accumulating on the tip of the teeth of the comb and clogging up the comb itself until the operator is forced to stop the machine for the necessary cleaning of the comb.
The mowing bars configured to make a scissor cut comprise two components, at least one of which moves with relative reciprocating motion with respect to the other, clamping the grass stem between the lower one and the upper one.
This type of bar makes it possible to obtain a clean and precise cut in all conditions, including very fine or flattened grass, and is insensitive to already cut grass, but requires accurate adjustment.
With this way of cutting, the pressure between the two blades is essential, having to zero the clearance between the cutters. Indeed, in the presence of clearance, since the tongue with contrast function is not present, the grass stem could bend and slip between the cutters with a consequent poor cutting quality.
A further differentiation between existing bars is relative to whether the lower comb in the scissor bars or the toothed comb in the contrast bars are fixed or also mobile with reciprocating motion like the upper blade.
Therefore, the bars can also be defined as single or double movement.
The big advantage of double movement bars is that it is possible to size the bar so as to achieve dynamic balancing, with consequent elimination of the vibrations caused on the machine and on the operator.
Summarizing, therefore, the prior art can be divided into the following four types:
An example of a bar configured to make a contrast cut with double movement is described in patent application no. MI2002A000911 to the same Applicant as the present patent application.
Inside the fourth type indicated above, that includes also the bar object of the present invention, it is common practice to make upper blades and lower combs of equal profile or in general of equal strength and masses, in such a way obtaining a bar that cuts thanks to the opposite motion of two blades.
Indeed, it is much simpler from the constructive point of view to make a control group that imparts two opposite movements of equal magnitude to both of the mobile elements.
Dynamic equilibrium is only reached, however, with the balancing of the products between the masses and the strokes of the two moving elements.
Consequence of this is, as stated earlier, that both moving elements, i.e. the upper and lower blades, may not have too different masses.
Otherwise the dynamic balancing is compromised.
Unfortunately, such common practice intrinsically means that the lower blade closest to the ground cannot in general be as strong as would be wished, for example to better withstand impacts, otherwise it would also be necessary to strengthen or increase the mass of the upper blade.
However, scissor cutting bars with double movement in which the lower blade is thicker than the upper blade are also known, for example from DE-U1-29615068.
Moreover, another drawback of known scissor cutting bars with double movement concerns the coupling currently used to fix the small blades to the blade strip that supports and guides them. Indeed, currently, for reasons of bulk due to the need to obtain the two planes of contact of the blades, as constraint for the small blades rivets with a frusto-conical head are used that, inevitably, under the action of the forces due to cutting, act as wedges, rapidly losing the attachment cohesion between the small blades and the relative supporting strip.
Once clearances have been established, during operation the integrity of the mechanism is quickly compromised.
Starting from such a prior art, the purpose of the present invention is to make a cutter bar configured to make a scissor cut with double reciprocating motion of the upper and lower cutting components that, by improving known ones, at the same time is particularly efficient.
In particular, the purpose of the present invention is to make a cutter bar configured to make a scissor cut with double reciprocating motion of the upper and lower cutting components, in which:
In general, these purposes are accomplished thanks to the fact that the lower small blades are real teeth and have greater mass, about double with respect to those of the upper blade, and have a much greater thickness.
From a dynamic point of view, the balancing is maintained thanks to a control group that imparts movements of unequal excursion to the blades.
Such control must be carried out, for example, by a control group as described in patent application MI2002A001003 again to the Applicant.
In this way, the stronger lower small blades are advantageously insensitive to impacts with respect to known embodiments.
Such an increased thickness allows a further advantage to be obtained.
Indeed, thanks to such greater thickness of the comb, it is possible to obtain on the plane of the lower teeth a seat, for example shaped like a concave groove, in which the projecting head of the rivets that fix the upper small blades can be housed.
In this way, the part of nail that fixes the upper small blades is cylindrical, no longer conical as currently is the case, with a consequent much stronger nailing, insensitive to impacts and easier to maintain.
Such a seat or concave groove operates at a central opening obtained on the small blades of the blade having a shape such as to have a uniform influence on flexural strength.
This opening decreases the mass of the blade, making it possible to size a comb that is consequently lighter, having lower inertia forces.
Another advantage of this opening is to allow the discharge of plant material, preventing accumulations between the blade and the comb.
This retaining of material is very harmful to cutting quality, because it wears down the moving parts and increases mechanical stresses.
The characteristics and advantages of a cutter bar configured to make a scissor cut with double reciprocating motion of the upper and lower cutting components according to the present invention will become clearer from the following description, given as an example and not for limiting purposes, referring to the attached schematic drawings, in which:
With reference to the figures, a cutter bar configured to make a scissor cut with double reciprocating motion of the upper blade and of the lower comb according to the present invention is shown with 10.
Such a cutter bar is of the type applicable to motor mowers or mowers and comprises:
The control group 16 is fixed with bolts 28 to the bar 10 and interacts with the blades 12, 14 through relative heads 29, 30.
Starting from such a configuration, according to the invention the lower small blades or teeth 13 have a greater thickness or mass than the upper small blades 15.
In particular, the lower small blades 13 have at least double the thickness of the upper small blades 15 and/or the lower blade or comb 12 has about double the mass of the upper blade 14.
The supporting bar 11 is associated, for example through bolts 27, with front shaped elements 26 that make a sliding track guide 18 for the lower blade 12.
In particular, the lower blade or comb 12 comprises a lower supporting strip 19 housed in the track 18, to which the lower small blades 13 are constrained, preferably with interposition of anti wear pads 24.
The upper blade 14 comprises an upper supporting strip 20, to which the upper small blades 15 are constrained through rivets 21.
The lower cylinder head 22 of the rivets 21 is housed in lowered seats 23 obtained on the upper face of the lower small blades or teeth 13.
The upper small blades 15 comprise a through-slot 31 at the lowered seats 23 to allow the discharge of plant material, preventing accumulations between the lower blade 12 and the upper blade 14 that constitute the mobile elements.
Finally, the cutter bar 10 comprises a restraint 25 for connecting the blades 12, 14 and the bar 11 and for countering transverse thrusts.
It has thus been seen that a cutter bar configured to make a scissor cut with double reciprocating motion of the upper and lower cutting components according to the present invention achieves the purposes outlined earlier.
Indeed, the bar described and claimed here offers:
The cutter bar configured to make a scissor cut with double reciprocating motion of the upper blades and of the lower comb of the present invention thus conceived can undergo numerous modifications and variants, all of which are covered by the same inventive concept; moreover, all of the details can be replaced by technically equivalent elements. In practice, the materials used, as well as their sizes, can be of whatever type according to the technical requirements.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102015000053525 | Sep 2015 | IT | national |
