SU1665956A1 - Knife for positive cutting of wood - Google Patents

Abstract

The invention relates to cutting devices for forest machines and can be used in the forest industry. The aim of the invention is to reduce wood cutting forces. The knife for power cutting contains spaced relative to the longitudinal plane of symmetry of the knife symmetrically relative to each other and fixedly interconnected lower 6 and upper 7 plates with opposing rows of cutting teeth 8 mounted on them, as well as scissoring teeth mounted between the plates in compliance with gaps for chip removal 9, the front face 20 of each of which faces in the direction opposite to the cutting teeth m, and the plane passing through the intersection lines of this face with the internal planes of the upper 7 bottom plates 6, intersects the longitudinal plane of symmetry of the knife at an acute angle and is inclined towards the rear of the blade, and the smallest distance between the internal planes of the plates 6 and 7 is determined from the following relationship: B ¹ * 98 (U _c + 0,02B) / 1.02, where B is the distance between the symmetry planes of plates 6 and 7

U _c is the distance between the projections of the vertices of the adjacent shear teeth on a plane perpendicular to the longitudinal plane of symmetry of the knife and the direction of thrust. 7 il.

Description

The invention relates to devices for power cutting wood and can be used in the forest industry.

The purpose of the invention is to reduce cutting effort.

Figure 1 shows schematically a power cutting knife mounted on a base machine, a plan; in Fig.2, node I ka Fig, 1; Fig. 3 is a view A in Fig. 2: ka of Fig. 4 is a part of the proposed knife with tearing out a portion of the upper plate, an axonometric projection; on .5 - section B - B on, 2, (one of the options); Fig. 8 shows a section B -B in Fig. 1 (one of the embodiments of the plates); Fig. 7 is a diagram of the formation and movement of chips.

The power cutting knife with the aid of the suspension 2 is installed on the side or in front of the base machine 3, which drives it. The knife can be used for power cutting of wood and in stationary conditions. At the same time, it is installed in longitudinal guide bases, with respect to which the knife is moved by any well-known forced displacement drive, thrust onto the fixed timber relative to the base.

At least one through hole 4 can be provided in the knife to reduce the pushing forces that are formed when cutting chips. Knife 1 consists of 5 separated from each other lower and 6 upper plates with opposing rows of cutting blades spaced along the height symmetrically relative to the longitudinal plane of symmetry. teeth 8 mounted on their sides, tooth 8 can be removable and secured by detachable connections on plates 6 and 7, tooth 8 can be made together with plates 6 and 7, between plates 6 and 7

in accordance with the gaps for the removal of chips, there are installed cleaving teeth 9. Each shearing tooth 9 is connected by means of connecting elements 10c each

from plates 6 and 7 (and thereby simultaneously connecting these plates together) by means of, for example, a rivet, screw or other known joint.

The cutting teeth 8 have a front 11 and

rear 12 faces, front 13 and rear 14 edges. The tops of the cutting teeth are indicated by the position 15.

The cutting teeth formation line, which is designated ef, connects the tips

15 cutting teeth 8. The width of the knife 1 is determined by the size of the width of its rear part 16 (Fig. 1) and depends on the maximum diameter of the Omax of the tree being cut (cut) 17. In addition to the connection between them through

the cutting elements 10 of the scaling teeth, the plates 6 and 7 are interconnected in areas 16 and 18 by the connecting elements 19 by means of a riveted, threaded or other connection. Lini ef

teeth 8 is at an angle cf. and the longitudinal axis OUa of the base machine 3, which coincides with the directions of its movement and thrust of the knife 1.

The angles of inclination of the front 13 and rear 14

the edges of the cutting teeth 8, as well as the front 11 and rear 12 edges of these teeth with respect to the longitudinal axis OiOa of the base machine can be selected on the basis of the existing recommendations concerning

the values of such angles for cross and chain saws

Taking into account that the angle a, which determines the direction of the line of formation of the cutting teeth ef with respect to the direction of subdivision Oi02, is set to the task of design the knife, then the location of the edges 13 and 14 and the faces 11 and 12 of the cutting teeth should be chosen relative to the line ef c

taking into account the angle "(the value of which is in the range of 8 - 15.

Thus, the front face 11 and the front edge 13 (with respect to the ef line can be located at an angle η in the range from (45 ° - a) to (100 ° - a). The optimum location of the front edges 13 and the face 11 will be when (90 ° - a), when the leading edge 13 will be located perpendicular to the wood fibers when cutting standing trees approximately (090 °).

The rear edge 14 and the face 12 can be positioned relative to the ef line in plan at an angle H ranging from (a + 10 °) to (a + 45). At the same time, the front edge 13 and the rear edge 14 and, respectively, the front 11 and rear 12 edges form among themselves in terms of the angle y, determined from the strength conditions of the tooth.

Each shear tooth 9 has a front face 20, which faces in the direction opposite to the cutting tooth m 8. The plane passing through the lines 21 and 22 of the intersection of this face 20 with the inner planes of the upper 7 and lower 6 plates, respectively, crosses the longitudinal plane of symmetry the knife (its mark in FIG. 3 is shown by the OCSM line) along line 23 (indicated by a two-dot-dash line), which is inclined at an acute angle Ј to the tangent 24, drawn in the specified plane of symmetry parallel to the plane of the drawing (the trace of which is OC) ) from point N corresponding to the projection on this plane of the top of one of the cutting teeth 8 of the upper 7 or lower 6 plates to the arc 25, described by a radius R equal to the feed to the tooth Uz from point M corresponding to the projection on the longitudinal plane of symmetry of the subsequent cutting tooth same plate.

Tangent 24 (line NN) is parallel to the longitudinal axis of the OchoA machine, and consequently, to the direction of advancement of the knife.

In the drawing, the construction of the tangent 24 is conventionally (for reasons of simplification of the drawing) shown on the top plate 7, since: such a construction in the longitudinal plane of symmetry will be similar and exactly the same as shown in the location. The front face 20 may be linear or concave, as shown in Figure 5. In the latter case, the most favorable conditions for smooth chip movement are created. The intersection line 22 of the face 20 with the inner plane of the bottom plate 6 will in the following be called the leading edge of the scaling tooth. Position 26 denotes the back face of each shear tooth 9. For the convenience of the subsequent presentation, we draw another plane, indicated by trace 27, perpendicular to the tangent 24 and the longitudinal plane of symmetry of the knife (parallel to the plane of the drawing). The trace of this plane is 27 on the top 7 plate.

passes through the points N and K.

As well as the intersection line 23, the front edge 22 is positioned relative to the plane passing through the tangent 24 (or the axis OY2) perpendicular to the longitudinal plane of symmetry at an angle Ј, and the rear face 26 at an angle p. A plane passing through the lines of intersection of the front face 20 of each splitting tooth with internal

planes of the upper 7 and lower 6 plates (and in the case of a rectilinear face 20, this face 20 itself) is inclined towards the rear part 16 of the knife and intersects the longitudinal plane of symmetry of the knife (its trace

on fig.Z it is designated OzOz) at an angle to it, equal 6.

The magnitudes of the angles and b are selected for reasons of providing the minimum force of knife thrust, as well as the rotation that the elements formed by cutting 90 ° (i.e., na envui them on one side) after interacting with the front edges of the 20 chipping teeth 9 for relatively short time The indicated rotation of chip elements on the side while ensuring the thicknesses of these elements, taking into account the elastic recovery, are equal to or less than the minimum distance b between the inner planes

plates 6 and 7 ensures a significant reduction in the force of chip pulling through the channels 28 for chip removal between the shear teeth. These channels are much larger in width of the height of the chip elements, taking into account its increase after elastic recovery.

To ensure compliance with these conditions, we consider the relationship between the forces occurring in the longitudinal plane of the knife parallel to the plates when each of the chip elements interacts with the front face 20 of the scaling tooth.

RGr force acting on the edge 20

decomposed into components, one of which acts in the feed direction of the knife, i.e. parallel to the line NN or Oi02 (PH), and the other (F & J) acts in the direction perpendicular to this line or parallel to Prgr

plane 27 passing through Liya NK. On the basis of this, the value of PGR can be determined through the force PH: FPP PH / ZI. and also through d PJj / cosЈ.

When the angle value is Ј 90, force РГр is equal to pushing force Рн. With a value of Ј 45 ° (the components of P $ and Pn are equal to each other, since Pf is sln45 ° Prp, cos45 °. Therefore, the angle of 45 ° should be taken outside the upper limit of Ј. In this case, the chip pull force and force knife advances have the same effect on chip movement.

As the angle decreases, the value of the compo- nent cade Rn decreases, and the value of the lateral component Pd increases (wedge effect). The effect of scabbing C5 from coal from angle g, however, the curve shows that when the angle is reduced to 10 °, a minimal reduction in effort is achieved, and a further decrease in the angle of egogue renders a noticeable decrease in effort.

Ph

By analogy, it is possible to justify the choice of the choice of the angle d when considering the relationship between the forces arising1 / in the interaction of each of the chip elements with the front face 20 of the longitudinal piezo of the knife, perpendicular his plates, Force rgr, acting in n of; planes that lie on the state of P1 nor {see fig. 3.).

Reducing the angles c and b below 10 ° privotst to gzbarmtov but:. IelSpAz. The elongation of akg. of teeth1: teeth, in addition, such abilities enms y: S-oE 4ygpov leads to: -the time of turning of the dreeesin fibers (i.e. turning chips on its side).

The magnitude of the angles d, as well as g, it is advisable to choose the E range from 10 to 45 °,

From the theory of cutting, it is known that the fibers of the wood after the cutting of the cutter are elastically restored, Therefore, the KSK indicated the minimum distance (b J between the inner surfaces of the plates 6 and 1 should be greater than the thickness of the chip element, taking into account its elastic recovery after the passage of the chipping tooth 9.

B1

U with +0.02 B

 + 2iu

where Uc is the distance between the projections of the vertices (for example, K and Kg of adjacent shear teeth on a plane perpendicular to the longitudinal plane of symmetry of the knife (

OZO on fig.Z) and the tangent 24 lying in it, drawn from the point corresponding to the point of symmetry of the top of one of the cutting teeth on this plane of symmetry

or the bottom plate to the arc described by the radius R, equal to the feed rate per tooth Uz from a point corresponding to the projection on the longitudinal plane of symmetry of the knife of the top of the subsequent cutting toothed

the same plate (the direction of advancement of the knife);

Uy is the value of the elastic recovery of shear wood fibers, depending on the wood species and microradius.

tops To the front edge KL of the rear face 26 of the splitting tooth 9. This edge of the rear face 26 of the tooth is indicated by the position 29. It is formed by the intersection of the front II) 20 of the rear edge 26, which is involved

v forming days cut.

As for Uy, its value in practice can be characterized in terms of the minimum value of the Poisson’s ratio g, shaft1 / level8 of which for wood

may have a value in the range of 0.02 ... and 83. Through this coefficient, the value of Uy can be expressed by the following relation

 )

where b and b are the distance between the plates, respectively, along the mx symmetry planes and the inner planes, g

almchina 7J- (b - b) characterizes the thickness

 "

each knife plate.

Considering that the minimum value of the coefficient g is 0.02. we substitute the found value Uy in the formula dll on the preposition b:

b1 UC -2 - g- (b-bVo.02

.one. Ds +0.028 As a result, b fo2

The distance Uy between the projections onto the plane 27 of the vertices of the scaling tooth and the nearest cutting tooth preceding it and in a direction parallel to the longitudinal plane of symmetry of the knife must be taken larger than the elastic recovery value of the fiber after the passage of the cutting tooth. This applies equally to the teeth of both the upper and lower plates, since one is positioned above the other, it is opposite. If we draw a line through ef, perpendicular to the longitudinal plane of symmetry of the knife, then it will cross the plane 27 along the line whose trace passes through point N, If we design

on the plane 27 of the top of the shearing tooth K and the top of the nearest cutting teeth of the upper and lower plates preceding it, it can be seen that the projection of the top of the shearing teeth is separated from the intersection line of the plane 27 with the plane passing through the line ef at a greater distance than the projection of the top specified cutting teeth. The differences in these distances are Uy

In this way, cutting is first carried out and then chipped, otherwise the cutting force is significantly increased.

To reduce the friction of the rear face 26 of the scaling tooth on the bottom of the cut, it is last inclined at an angle. p to the feed plane (i.e. the plane passing through the points NN1 perpendicular to the longitudinal plane of symmetry of the knife). The magnitude of this angle is usually taken in the range of 5 to 10 °.

To reduce the friction of the plates 6 and 7 about the walls of the cut and reduce the force of friction of chips in the channel 28, the inner and outer planes of each plate can be made converging relative to the longitudinal plane of its symmetry 30 and 31

(General,) at an angle in the direction opposite to the cutting tooth mounted on these plates and a perpendicular line passing through the tops of these teeth. According to the cutting theory, the angle value / can be taken within 3 ... 6 °.

4, the knife is shown in an axonometric projection, where the dash-dotted line with two points conventionally shows the trace of the longitudinal plane of symmetry of the knife. With respect to this plane, the front face 20 of the scaling tooth is inclined at an angle d.

Knife for power cutting of wood works as follows.

The knife 1 slides onto the tree trunk 17 using the base machine 3 (or any drive) in a translational motion in the direction of the arrow indicated in the drawing. At the same time, the cutting teeth 8 of the lower b and the upper 7 plates enter the first turn in contact with the barrel 17. The cutting teeth 8 cut the fibers of the wood across its fibers at a distance from each other equal to the distance between the tips of the teeth, measured in the direction perpendicular to the longitudinal plane of symmetry of the knife. In Fig.7 schematically shows the trajectory (line) of the passage of the teeth of the lower and upper plates 6 and 7 (themselves

plates 6 and 7 are conventionally not shown). Thus, the tooth 8 of the lower and upper plates form an unseparated chunk 2 of wood. With the further movement of the knife 1 ne 5 chunk 32, a cleaving tooth 9 advances, which with its tip penetrates into the chunk from the lower end and begins to tear it away from the main trunk 17 of the tree. The splitting of the slit 32 starts from below and

0 simultaneously by the action of the leading edges 29 and 22 of the wood particles begin to move away from chunk 32, Since the front face 20 of the shear tooth 9 is inclined with respect to two planes: at an angle Ј and

5 feed plane, i.e. the plane passing through the tangent 4, perpendicular to the longitudinal plane of symmetry of the knife, and at an angle of 5 to the longitudinal plane of symmetry of the knife, the cut elements

The chips are forced to rotate 90 ° (sideways) to the position in which the wood fibers are located parallel to the longitudinal plane of symmetry of the knife or along the inner plane of the bottom plate. The shortest distance b between the plates 6 and 7 along their internal planes is assumed to be of such a size that no chips jam in the channel 28. This condition is met if the thickness

0 chips 33 (Uc), taking into account its ug-hcgs recovery, will be less than the distance b.

Mathematically, this condition is expressed by the indicated formula to determine the value of b.

If the chips with a thickness Uc are turned by a chipping tooth by 90 °, then with axial thickness it fills the space between the inner planes of the plates 6 and 7, B

In reality, the chip thickness Uc is larger by the amount of elastic cutting of the cutting planes by the edges 29 of two adjacent shear teeth, i.e. by 2 Uy. So distance b

5 between plates 6 and 7 must be equal to or greater than the value of Uc - 2Uy. Compliance with this condition allows chips 33, directed by their fibers along plates 6 and 7, to pass freely between them.

0 in the direction shown by arrow 34.

Upon further movement of the knife under the action of the pressure of the subsequent chipping particles, the preceding chip elements will fall out either into the window 4, or

5 charez back 16 knife 1.

Claims (1)

Invention Formula A knife for power cutting of wood containing symmetrically spaced relative to the longitudinal plane of symmetry and fixedly interconnected lower and upper plates with opposite rows of cutting teeth mounted on them, as well as scissor teeth mounted between the plates with the formation of gaps, the front face of each of which faces the side opposite to the cutting tooth, m, characterized in that, in order to reduce the cutting forces, the plane passing through the lines of intersection of the front edge dogo shear tooth with the internal planes of the upper and lower plates, is inclined towards the back of the knife and the knife intersects the longitudinal plane of symmetry an angle of 10 - 45 °, th and the smallest distance between the inner planes of the plates is determined from the dependence 5, Uc -f 0.02V b-con- where sp is the distance between the projections of the vertices of the adjacent shear teeth on the plane perpendicular to the longitudinal plane of symmetry of the knife and the direction of thrust; B is the distance between the planes of symmetry of the upper and lower plates. ; Type A B-y rv B - 8 is covered No thirty / Off FIG. 6 23 22 34