FR2621443A1 - SEGMENT KNIFE FOR A CUTTING APPARATUS OF AN AGRICULTURAL MACHINE - Google Patents

Abstract

The segment knife for cutting device is used for pruning shrubs and has parallel upper 4 and lower 5 faces, a drive means 3 a base 2 and a nose 1. The blades 6 and 7 of the knife have sharp edges 8 and 9 having a curvilinear profile and a variable thickness along their length and progressively increasing from the beak 1 to the base 2, which makes it possible to reduce the deformation of the branches to be cut.

Description

The present invention relates to machine cutting devices

  preferably used for pruning hard-stemmed plants and shrubs, for example tea trees, and in particular relates to a knife

  with segments for cutting apparatus for these machines.

  We know, in the SU.A. 952 153, a segment knife for the cutting device of an agricultural machine having two lower and upper parallel surfaces, a base, a beak and blades with sharp edges

  have a straight profile, each of said edges being formed

  mé by the intersection of a lateral bevel and a lower surface. However, this knife requires having a high power necessary to ensure the process of cutting plants. This drawback is due to the fact that the blades of the knife, whose sharp edges have a straight profile, ensure an oblique cut of the plants, which

  is much less advantageous than sliding cutting.

  We also know, in the SU.A. 917 767, a

  segment knife comprising upper and lower surfaces

  parallel, a drive means, a base and blades whose sharp edges have a curved pattern, each of said edges being formed by the intersection of the lateral and lower bevels. This knife has a thickness

  constant along the length of the blades.

  However, this knife also needs high power to ensure the cutting process of

  plants, especially twigs of shrubs (stems of the-

  certain species), the diameter of which exceeds the

  total width of the cutting segment blades and the

  tre-segment. This is because during the penetration of

  tion of the blade in a twig to cut the latter is

  deformed by the side bevels and, when the depth

  the size of the cut does not exceed the width of the blade,

  segment penetration takes place with the minimum of energy

  necessary thanks to the kinematic transformation of

  the angle of the blade sharpening and the sliding cut

  Compared to the oblique cut, the slip cut ensures a gain in strength for the depth of the notch equal to the width of the segment blade thanks to

  reduction of material deformation and trans-

  fert of the frictional force from the direction normal to the tangential direction, During the subsequent penetration of the segment blade into a branch to be cut, the bevels of the blade cause, due to the constant thickness of the blade, the deformation of the plant's wood over the entire height and length of the notch, which creaks until reaching the value of the diameter of the branch to be cut, which results in the maximum increase in the forces of resistance to deformation of the stems under the action of the lateral and lower bevels, and of the friction forces of the wood against

  the lateral and lower bevels as well as against the fac-

these upper and lower.

  It has therefore been proposed to create a segment knife for the cutting device of an agricultural machine in which the blades are made so as to reduce the resistance to cutting resistance of the branches to be cut, to increase the depth and the width. notch everything

  by reducing its height, and thus reducing the deformation

  tion of the wood and the power required to cut the branches. The problem, thus posed, is solved using

  a segment knife for a cutting machine

  agricultural china with upper and lower faces

  parallel parallel, curvilinear profile blades, edges

  your sharp edges, each formed by the intersection of the

  lateral bevel with the lower bevel a means of

  undercarriage, a base and a spout, characterized, according to the

  vention, in that the thickness of the blades is variable following

  the length and gradually increases from the beak towards the base, According to the embodiment node of the invention, the variable thickness of the blade is obtained by forming, on the upper face of the knife, along the contour of the blades, additional faces inclined to the underside and going from the base to the beak of the segment knife. It is advantageous that

  the additional inclined faces form, in conjugation

  bran with the upper side of the segment knife, a

stiffness rib.

  By making the knife blades with a thick-

  19 sor variable along the length, reducing the height of the notch as the blade penetrates the material (branch) to be cut and, therefore, the deformation of the wood. This results in a reduction in the strength of the deformation resistance of the twig wood.

  under the action of the lateral bevel and the force of rubbing

  wood against the side and bottom bevels as well

  only against the upper and lower faces, which

  helps reduce energy consumption for the pro-

stopping cutting of twigs.

  The realization of the stiffness rib makes it possible to ensure the rigidity of the segment knife in the transverse plane and, therefore, to prevent the edges of the

  blades of the cutting segments and counter-segments collide

tent in the cutting device,

  In comparison with knives with concealed segments

  bare, the indicated properties of the next segment knife

  the invention make it possible to significantly reduce the consumption

  energy for the branch cutting process, which allows, if the cutting devices are equipped with the

  proposed segment knife, use a mini power

  male. The invention will be better understood and other objects, details and advantages thereof will appear better on

  reading of the explanatory description which follows

  embodiment given only by way of nonlimiting example with reference to the nonlimiting drawings in which: - Figure 1 shows a top view of a segment knife according to the invention; - Figure 2 shows the segment knife of Figure 1, in front view; - Figure 3 illustrates another embodiment of the segment knife from above; - Figure 4 is a front view of the segment knife shown in Figure 3; - Figure 5 is a side view of the segment knife shown in Figure 3; - Figure 6 shows part of the cutting device

  equipped with segment knives according to the invention.

  The segment knife of the cutting device of an agricultural machine comprises a beak 1 (Figure 1), a base 2, a drive means 3, an upper face 4 (Figure

  2) and a lower face 5, blades 6 and 7. curved profile

  vilinate with cutting edges, respectively,

8 and 9.

  The cutting edge 8 of the blade 6 is formed by the lateral bevel 10 and the lower bevel 11 and the cutting edge 9 of the blade 7 is formed by the lateral bevel

12 and the lower bevel 13.

  The blades 6 and 7 have, depending on their length

  gueur, a variable thickness h which gradually increases from the spout to the base 2, that is to say from

  thickness h to thickness h1.

  According to another embodiment shown in FIGS. 3 to 5, the knife with blades 6 and 7 of variable thickness, comprises, on the upper face 4 along the contour of the blades 6 and 7, additional faces 14 and

  respectively, inclined with respect to the underside

  5 and going from the base 2 to the spout 1, These additional faces 14 and 15 form, in conjugation

  with the upper face 4j a stiffening rib 16.

  The segment knife object of the invention

  tion finds its application in cutting devices

  of agricultural machinery, The cutting apparatus includes a con-

  tre-knife 17 (Figure 6) fitted with segments 18 and

  segment plates 19 according to the invention mounted mobile on the counter knife 17 via the axes 20 and coupled to said counter knife 17 via the axes 21, At the places where the axes 20 are arranged, it

  longitudinal grooves 22 are provided on the counter

  knife 17 and transverse grooves 23 on the

  teaux à segments 19, The segment knives 19 and the counter knife

  17 are mounted on a bar 24, the axes 20 of which engage

  gent in the longitudinal grooves 22 of the counter knife 17 and the transverse grooves 23 of the segment knife 19, The segments 18, called counter segments in the text

  which will follow, have upper-and lower-sides

  re parallel, cutting blades with sharp edges

  your 25 and 26 have a curved profile (concave) and formed, according to the invention, by the lateral bevels and the lower surface.

  The cutting device using the cutting knife

  ment according to the invention operates as follows.

  The reciprocating rectilinear movement of the counter-neck

  sheet 17 (Figure 6) driven by the control (not shown in Figure 6) is transmitted by the axes 21 to the segment knives 1 and is transformed via the axes 20 fixed on the bar 24 in oscillatory movement

segment knives 19.

  The longitudinal grooves 22 of the counter knife 17 and the transverse grooves 23 of the segment knives

  19 ensure the kinematics of the alternating rectilinear movement

  tif of segments 18 of counter knife 17 and of movement

  oscillation of segment knives 19 assu-

  the wedging and cutting of the branches penetrated into

  the openings existing between each pair of the counter-seg-

  ments 18 and cutting segments 19, The process of cutting a twig stuck in the opening formed by the knives. segments 19 and them

  counter-segments 18 is carried out in the following manner.

  By penetrating into the wood of the twig, the cutting edge 8 performs the prior tightening of the layers of the twig wood then it cuts them at the moment when the destruction stress is formed from in contact with the edge

sharp 8.

  Simultaneously with the destruction of the following layers of wood by the cutting edge 8 of the blade 6, the lateral bevel 10, the lower bevel 11 of the blade 6 of the segment knife and the bevel of the blade 25 or 26 of the counter segment 18 begin to deform the already cut layers. As the blade 6 penetrates into the branch to be cut, the bevel 10 or 11 and, by

  example, the bevel of the blade 26 undergoes the cross-action

  health of directed compressive strength forces

  in the opposite direction to the direction of movement of the bi-

  buckets and deflection resistance forces directed perpendicular to the underside. Moreover, the

  bevels participating in the cut undergo the action of the

  those of resistance to deformation of wood, which constitute

  the sum of projections of the forces of resistance to com

  pressure and deflection resistance forces on the

  direction of normal to the bevels participating in the cut.

  Normal forces of resistance to deformation

  tion of the wood gives rise to friction forces acting on the bevels 10 and 11 and the bevels of the counter-segment as well as on the underside 5 of the segment knife

  19 and the underside of the counter-segment 18 which partici-

can cut,

  During this phase, the sum of the forces of re-

  resistance to deformation of the wood of the twig acting on the bevels 10 and 11 of the blade 6 is much smaller

  that the force of resistance to deformation of the wood of the ra-

  meau acting on the bevel of the counter-segment blade

  18, This state of affairs is due to the fact that the movement

  latoire of the segment knife 19th the convex profile of the cutting edge 8 and the shape of the bevel surfaces and 11l ensure a reduction in the angle of attachment of the blade 6 in the direction of movement of the points of the edge

  sharp 8. The sharpening angle of the counter-blade

  plate 18 remains constant in the direction of speed of movement

  alternative. In addition, the cutting blade 6 simultaneously performs

  ment the destruction of the layers of the wood of the ...

  cutting edge 8 and their deformation by bevels 10 and 11 over a shorter length compared to that of the blade of the counter-segment 18, which is conditioned by the convex cutting edge of the segment knife 19,

  the concave cutting edge of the counter-segment 18 and the sec-

  convex tion (circumference or ellipse) of a branch. The

  fineness of the convex cutting edge 8 animated by a movement-

  the oscillating knife in the segment knife 19 decreases during its angular displacement while the sharpness of the concave cutting edges 25 or 26 of the counter-segment

remains constant.

  The aforementioned working conditions of the

  cutting blade 6 of the segment knife 19 ensures, in

  parison with the working conditions of the cutting blade

  eg of the counter-segment 18, a decrease in the force of

  resistance to deformation of the wood of a branch thanks to the segment knife 19, which conditions a greater depth of penetration of the cutting blade 6 into the branch to be cut,

  The component of the forces of resistance to the

  bending acting on the bevels 10 and 11 of the segment knife 19 and the force of resistance to deflection opposing the bevel of the counter-segment 18 cause a bending of meeting of the segments 19 and 18 in the planes

vertical and longitudinal.

  As the blade 6 of the segment knife 19 penetrates into the branch to be cut to a depth greater than the width of the bevel 10, the inclined face 14 ensures a progressive reduction in the width of the bevel 10 and in the thickness of the blade 6 cutting the branch, This determines the decrease in the height of the notch in the branch with an increase in its depth,

262 1,443

  THE decrease in height with the increase in the notch in the twig and the simultaneous increase

  the length of the notch, which are a function of the

  me of the blade 6 and the section of the branch at the point of cutting, make it possible to minimize the volume of the deformation of the wood of a branch during cutting, which

  minimizes compressive strength

  and deflection acting on the bevel 10 of the

  me 6 of the knife segment 19. The reduction in the compressive and deflection resistance forces acting on

  the bevel 10 to the minimum value causes the dimi-

  nution to the minimum value of the normal force and, with this, the reduction of the friction force of the wood

  against bevels 10, 11, and faces 4 and 5.

  The bending of the segment knife 19

  and segments 18 of the counter knife 17 which appears during

  during the cut due to the action of the forces of resistance to deflection, is compensated by the distance separating the cutting edge 8 from the face 5 of the segment knife 19 formed by the lower bevel 11, which excludes contact and

  chipping of sharp edges 8 and 25 or 26.

  The width of the inclined face 14 ensures the

  eg free of the twig, without the latter abutting, during the cutting process, against the rib. of rigidity 16, which contributes to the increase in flexural strength

  of the knife segment 19 in the vertical and longitudinal plane

  nal. Minimizing all the reactive forces of the resistance acting on the bevels 10 and 11 of the blade 6 and the face 5 of the segment knife 19 makes it possible to cut the main part of the section of a branch and reduce the energy consumption necessary to ensure the cutting process of twigs, shrubs and plants with hard stems, whose diameter is larger than the total width of the

  side bevels of segment knife 19 and counter

segment 18,

Claims (3)

  1, Segment knife for cutting device of an agricultural machine comprising parallel upper (4) and lower (5) faces, blades (6-and 7)   having sharp edges (8 and 9) with curved profile   gene, each formed by the intersection of a lateral bevel with a lower bevel, a drive means (3), a base (2) and a spout (1), characterized in that the thickness of the blades (6 and 7) is variable along the length and gradually increases from the beak (1) to the base (2).   2. Segment knife according to claim 1, characterized in that it comprises, on the upper face (4) of the knife along the contour of the blades, additional faces (14 and 15) inclined relative to the lower face (5 ) and going from the base (2) to spout (1).   3. segment knife according to claim 2, characterized in that the additional faces (14 and 15) form with the upper face (4) a rib of rigidity (16).