FR2470528A1 - V=section mower knife - has transverse portion of end fixing area of same nature as cutting area - Google Patents

Abstract

The mower knife has an area along its lengthwise axis by which it is secured to a support, and another one for cutting the fodder. A transverse portion of the latter and is at a different height. A portion of the fixing area (1) at right angles to the lengthwise axis (3), has a shape of the same nature but different from the cutting area (2). At any point along the lengthwise axis there can be transverse sections at a different height from the ends, typically of wide inverted-V shape. The fixing area can have a vertical wall round the edge, running in a semi-circle.

Description

The present invention relates to a mower knife.

 There are mower knives in various shapes. The majority of these knives are entirely flat and substantially rectangular. They have along their longitudinal axis an area intended for cutting the forage comprising at least one cutting edge, and an area intended for fixing said knife to a support intended to communicate to the latter a movement suitable for cutting the forage.

 The knives described above present the disadvantage of being easily deformed when the cutting area meets an obstacle such as a stone masked by the fodder to be cut. Furthermore, a deformed knife can in some cases damage the machine on which it has climbed.

 To remedy this drawback, a knife has been designed whose area intended for cutting is arched or profiled in order to present greater rigidity to deformations, in particular to folding in the event of impact. The area intended for fixing this knife remains entirely flat, however, in particular because of the small size which the fixing device of such a knife must have.

I1 follows that when this type of knife suffers a shock, it deforms not in the area intended for cutting but in the area intended for fixing it so that this knife has the same drawbacks as those described above. .

The present invention, however, relates to a knife, the particular shapes of the zones intended for the compe of the fodder and for its fixing allow either to increase the resistance to deformation in the event of an impact, even, with resistance equal to deformation relative to the knives of known types, of made of a material has both different mechanical characteristics or a smaller thickness. This reduced thickness also has the advantage of being able to produce a knife requiring no sharp part or any sharpening. Indeed, given its high speed of movement the thickness of such a knife is sufficient to constitute by itself a cutting edge capable of cutting the forage. For this purpose the thickness of the knife is not more than two millimeters.

 The particular forms of the knife according to the invention therefore make it possible to increase its safety in use, to reduce its cost price and to lower its dead weight.

Such results have been obtained thanks to the fact that a section of the area intended for cutting the forage made through the longitudinal axis of the knife according to the invention determines a shape comprising at least one part situated at a height different from those of the ends of said shape, while a section of the area intended for the fixing of said knife made through its longitudinal axis determines a shape of a kind but nevertheless different from that of the section of the area intended for cutting fodder.

 This arrangement makes it possible to significantly increase the rigidity of the knife along each of these zones, that is to say over its entire length. To this end, at any point on the longitudinal axis of the knife, sections made through the latter determine shapes having at least one part situated at a height different from those of the ends of said shape.

Other characteristics and advantages of the invention will appear below in more detail in the non-limiting description of an exemplary embodiment of the invention and with reference to the accompanying drawings in which: - Figure 1 shows a top view in perspective
of a knife according to the invention, - Figure 2 shows on a larger scale a section
according to II-II of Figure 1, - Figure 3 shows on a larger scale a section
according to III-III of Figure 1.

 As shown in Figure 1, the knife according to the invention has substantially an elongated rectangular shape. The free end of its zone (1) intended for its attachment to a support is rounded, while the free end of its zone (2) intended for cutting the forage is straight. This knife has a longitudinal axis of symmetry (3) which passes on the one hand at equal distance from the two cutting edges (4 and 5) of the zone (2) intended for cutting the fodder and on the other hand through the center of a through hole (6) provided for fixing the knife to its support.

The latter which is not shown in the accompanying drawings, may for example other either a disc of disc mower, or a member for fixing the cutting elements of a drum mower, or a blade of lawn mower, the knife according to the invention preferably being intended to be fixed on a support entered born in rotation for the purpose of cutting the fodder.

 In FIGS. 1 and 2 it can be seen particularly clearly that the zone (2) of the knife intended for cutting the fodder is arched by being made up of two flat parts (7 and 8) inclined in opposite directions with respect to the other and contiguous along a line corresponding to the longitudinal axis (3) of the knife The section of this zone (2) therefore has a widely open inverted V shape. As a result, the central part (9) of the zone (2) is very thin and is situated at a height different from that of the lateral ends of said zone (2) formed by the edges (10 and 11) of the cutting edges (4 and 5).

The rigidity of this area (2) is therefore increased compared to knives of known type having an area intended for cutting completely flat forage. This increased rigidity therefore allows the knife according to the invention to better resist the folding forces exerted on said knife when the latter encounters an obstacle when cutting the forage.

 The shape of the section of the zone (2) intended for cutting the fodder and made by a plane perpendicular to the longitudinal axis (3) of the knife, as can be seen in FIG. 2, remains substantially constant from the free end of said zone (2) to its other end.

The latter is connected to the zone (1) of the knife intended for its attachment to a support. The total length of the zone (2) corresponds substantially to the length of the cutting edges (4 and 5) extending along the outer edges of the parts (7 and 8) of the knife.

The zone (1) adjoining the zone (2) of the knife present in section made by a plane perpendicular to the longitudinal axis (3) of the knife, as can be seen in FIG. 3, a shape comprising a central part ( 12) relatively wide and located at a height different from that of the lateral ends of said zone (1). The section of this zone (1) has substantially the shape of an inverted U having a large central part (12) and short lateral parts. These lateral parts delimit the edge of the zone (1) of the knife by forming a substantially vertical wall (13). This vertical wall (13) extends substantially in a semicircle at the free end of the zone (1) intended for fixing the knife.

The rigidity of the zone (1) of the knife according to the invention is thus also increased compared to knives of known type having an entirely planar fixing zone.

So that there is no zone of weakest resistance in the knife according to the invention, the transition between the zones (1 and 2) of the knife takes place gradually. As a result, the width of the central part (12) of the zone (1) has, when viewed from above, substantially a triangle shape, one of the vertices (14) of which is situated on the longitudinal axis (3) of the knife and between the parts (7 and 8) of its zone (), while two of the edges (15 and 16) of the triangle depart in divergence from this vertex (14) in the direction of the semicircular vertical wall (13) described above above.

 According to an additional advantage of the invention the center of the semi-circular vertical wall (13) corresponds with the center of the through hole (6) of the member for fixing the knife to its support. This member, not shown, is generally constituted by a screw, the head of which is housed inside the volume delimited by the wall (13).

The head of this screw preferably has a diameter very slightly less than the internal diameter delimited by the vertical wall (13). Thus by providing a passage hole (6) sufficiently large for the body of the screw, the knife according to the invention will come s lean on the head of said screw when said knife, driven in rotation by the support to which it is connected, will tend to be ejected outwards under the action of centrifugal force. the screw on the vertical wall (13) being significantly larger than the wall of the through hole (6), the pressure and consequently the wear of the parts in contact will be reduced. On the other hand, the frictional forces ensuring at least the knife stability increases due to the increase in the bearing surface. This results in greater stability of the knife and therefore greater cutting force since the knife has more difficulty in moving away from its most favorable position for cutting.

 The arrangement of the wall (13) of the zone (1) of the knife therefore makes it possible to reinforce this zone by making it more resistant to folding given its shape in One while protecting the head of the fixing screw, without however increase the size of the knife attachment device.

 The present invention is therefore remarkable in that each of the zones (1 and 2) of the knife is designed to resist folding while being the best suited to fulfill their own function consisting respectively in securing the knife and cutting the fodder. .

 It is obvious that we can still bring to the embodiment of the knife described above, various improvements, modifications or additions and that we can replace certain elements with equivalent elements without departing from the scope of the invention.

Claims (7)

1. Mower knife having along its axis  longitudinal an area intended for its attachment to a support and an area for cutting fodder, a section of this latter zone, made across said long axis  tudinal, determining a form comprising at least one  part located at a height different from that of its  ends, said knife being characterized by the fact  that a section of its zone (1) intended for its fixing, made through said longitudinal axis (3), determines a  shape of the same kind but nevertheless different from that  of the section of the zone (2) intended for cutting the  feed. 2. Mower knife according to claim 1, character  laughed at by the fact that at any point on its longitudinal axis (3) sections made through it determine  shapes having at least a portion located at a  height different from that of the ends of said form. 3. mower knife according to claim 1 or 2, characterized by the fact that the section through its  longitudinal axis (3) of the area (2) intended for cutting fodder, has a substantially V shape  inverted wide open. 4. mower knife according to claim 1, 2 or 3,  characterized by the fact that the section through its longitudinal axis (3) of the area (1) intended for its fixing, has substantially the shape of an inverted U. 5. Mower knife according to claim 4, charac terrified by the fact that the zone (1) intended for its fixing tion is bordered by a wall (13) substantially verti wedge. 6. Mower knife according to claim 5, character  laughed at by the fact that the vertical wall (13) extends substantially on a semicircle at the end of the area  (1) intended for fixing the knife. 7. mower knife according to claim 5 or 6,  characterized by the fact that the vertical wall (13)  is substantially concentric with the through hole (6)  of a member fixing the knife to its support.