RU2488482C1 - Method of log cutting into timber - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to saw milling. Log type is defined, log diameter is measured, initial and final moisture content are measured. Log and square log cutting pattern is selected. Log is cut into square log and timber. Square log is cut into timber. Note here that possible losses in quality of cut timber in further drying are allowed for. Prior to selecting cutting pattern log and square log favorable zones are forecast to allow minimum losses in quality caused by buckling, cracking and polythickness. Distance from log and square log axis to outer face are measured for every plank to allow selection of plank width with minimum shrinkage factor of inner and outer faces. Forecasting can be performed using difference in shrinkage factors plotted to make a graph describing timber type, final moisture content, plank width, distance from log axis, and that of square log to plank outer face. Forecasting may also be effected using computer programs.

EFFECT: higher quality of sawn timber.

3 cl, 13 dwg

Description

The invention relates to the sawmill industry and can be used in methods of cutting logs and beams into lumber.

A number of methods are known for cutting raw materials into lumber, providing for improving the quality of sawmill products and maximizing the use of wood raw materials due to the rational selection of nominal sizes of sawn materials and their location in the set (cutting pattern) depending on the diameter of the sawn log and the purpose of sawn products (Yu.R. Bokshanin “Processing and use of larch wood.” - M.: Timber industry, 1973, pp. 82-102; V.F. Vetsheva “Cutting large logs into lumber.” - M.: Timber industry b, 1976).

Known methods are aimed at providing gross, volumetric indicators and lead to the production of different thickness boards due to the lack of adjustment of allowance for shrinkage for individual sawed boards.

There is a method of cutting logs into lumber, which improves the quality of lumber by reducing their thickness due to the appointment when cutting allowance for shrinkage in thickness depending on the position of the board relative to the axis of the log (RU No. 2038945, publ. 1995 - prototype).

A disadvantage of the known technical solution is that it does not predict and does not take into account the possible loss of sawn timber (boards) during their subsequent drying due to warping, cracking and thickness variation, which reduces the quality of sawn timber.

The technical task of the invention is to increase the efficiency of the method of cutting logs by improving the quality of sawn lumber due to the implementation of the method of cutting logs, as well as timber, taking into account possible loss of quality of the sawn materials during further drying.

This object is achieved by the fact that in the claimed method of cutting logs into lumber, including determining the breed, measuring the diameter of the log, setting the initial and final moisture, setting the cutting pattern of the log, as well as the beam, sawing the log into timber and lumber, and also sawing the beam into lumber - the method is carried out taking into account possible loss of quality of sawn lumber during their further drying, while before assigning a cutting pattern, favorable zones of the log and the beam are predicted, I provide the output of lumber with minimal loss of quality during further drying due to warping, cracking and thickness variation, determine for each board the distance from the axis of the log, as well as the beam to its outer layer, according to which, when assigning a scheme for cutting the log, and also the beam - from the favorable zone, choose the width size of each board, characterized by the smallest difference in the drying coefficients of its inner and outer layers.

Prediction can be carried out according to experimentally obtained taking into account the indicator of the difference in the coefficients of shrinkage of the inner and outer layers of the boards - a diagram containing the breed, final moisture, thickness, width of the boards, the distance from the axis of the log, and also the beam to the outside of the board.

Prediction can also be done using computer programs.

The invention has the following differences from the prototype:

- the method is performed taking into account possible quality loss of sawn lumber during their further drying;

- before the appointment of the cutting scheme, favorable zones of the log and the beam are predicted, which ensure the output of lumber with minimal loss of quality during further drying due to warping, cracking and thickness variation;

- determine for each board the distance from the axis of the log, as well as the beam to its outer layer, according to which, when assigning the cutting scheme of the log, as well as the beam, the width of each board, characterized by the smallest difference in the coefficients of shrinkage of its inner and outer layers, is selected from the favorable zone ;

- forecasting can be carried out according to the experimentally obtained taking into account the indicator of the difference in the coefficients of shrinkage of the inner and outer layers of the boards — a diagram containing the breed, the final moisture, thickness, width of the boards, the distance from the axis of the log, and also the beam to the outside of the board;

- prediction can be performed using computer programs.

This will improve the efficiency of the method of cutting logs by improving the quality of sawn timber due to the implementation of the method of cutting logs, as well as timber, taking into account possible losses in the quality of sawn materials during further drying.

In the patent information fund we reviewed, no similar technical solutions, as well as technical solutions containing the indicated features, were found.

The invention is applicable and will be used in the industry in 2012.

Figure 1 shows the sawed board in the coordinate system.

On figa) shows the calculated cross-sectional shape of the boards as a result of drying.

On figb) shows the experimental shape of the cross sections of the boards as a result of drying.

Figure 3 is a graph showing the transverse warping of the inner and outer layers of pine lumber.

Figure 4 is a graph showing the thickness difference of sawn timber from pine as a result of drying.

Fig. 5 is a graph showing chip losses due to lateral warping of pine sawn timber as a result of drying.

On figa) shows a graph that allows you to determine the difference in the coefficients of drying of the layers of boards of different widths for pine boards with a thickness of 10 mm

On figb) shows a graph that allows you to determine the difference in the coefficients of drying of the layers of boards of different widths for pine boards with a thickness of 45 mm

Figure 7 shows a graph for determining the width of the board with the smallest difference in the coefficients of shrinkage of the layers.

On Fig shows a diagram for predicting the pattern of cutting logs from larch.

Figure 9 shows a diagram of the cutting of logs (first pass).

Figure 10 shows a diagram explaining the appropriate cutting of logs within the zone in which the warping and cracking of lumber is greatest.

Figure 11 shows a diagram for predicting a pattern of cutting softwood logs.

The development of the claimed technical solution was carried out by the following studies.

When conducting research, the location of the sawed board relative to the axis of the log in the coordinate system was considered (figure 1),

where a ₁ , a ₂ - the distance from the axis of the log to the left and right edges of the board, respectively, mm;

b ₁ - coordinate of the inner face of the board, corresponding to the distance from the axis of the log to the inner face of the board, mm;

b ₂ - coordinate of the outer surface of the board, corresponding to the distance from the axis of the log to the outer surface of the board, mm;

θ is the angle of inclination of the radius vector drawn at the point of interest on the board face to the X axis;

point 0 (origin) - the geometric center of the cross section of the log through which the longitudinal axis of the log passes, the contour of the cross section of which is shown in the form of a circle centered at point 0.

It is established that uneven shrinkage of wood with a decrease in hygroscopic humidity leads to a change in the size and shape of the cross-sections of lumber. Unequal shrinkage of board planks is the main reason for the appearance of lateral warping, the excess of which over the permissible standard value reduces the grade of sawn timber after drying.

Quantitatively, the shrinkage of wood in various directions is estimated by the corresponding coefficient of shrinkage.

Unequal shrinkage of the layers, numerically characterized by the difference in shrinkage coefficients, is the main reason for the appearance of lateral warping of the boards during drying, which is calculated by the formula:

- for the inner face:

$$f_{K\mathrm{one}}=\left(\mathrm{one}-\frac{\Delta W}{\mathrm{one\; hundred}}{K}_r\right)\sqrt{{\mathrm{<figure-callout\; id="2"\; label="a"\; filenames="00000014.png,00000016.png"\; state="\{\{state\}\}">a</figure-callout>}}_2^2+b_{\mathrm{one}}^2}\left\{\cos \left[\frac{\mathrm{one}-\frac{\Delta W}{\mathrm{one\; hundred}}{K}_t}{\mathrm{one}-\frac{\Delta W}{\mathrm{one\; hundred}}{K}_r}arctg\frac{a_2}{b_{\mathrm{one}}}\right]-\cos \left(arctg\frac{a_2}{b_{\mathrm{one}}}\right)\right\}\left(\mathrm{one}\right)$$

- for the outer layer:

. $${\mathrm{<figure-callout\; id="2"\; label="f\; K"\; filenames="00000014.png,00000016.png"\; state="\{\{state\}\}">f\; </figure-callout>}}_K=\left(\mathrm{one}-\frac{\Delta W}{\mathrm{one\; hundred}}{K}_r\right)\sqrt{a_2^2+{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="00000014.png,00000016.png"\; state="\{\{state\}\}">b</figure-callout>}}_2^2}\left\{\cos \left[\frac{\mathrm{one}-\frac{\Delta W}{\mathrm{one\; hundred}}{K}_t}{\mathrm{one}-\frac{\Delta W}{\mathrm{one\; hundred}}{K}_r}arctg\frac{a_2}{b_2}\right]-\cos \left(arctg\frac{a_2}{b_2}\right)\right\}\left(2\right)$$

.

where f _K1 - lateral warpage for the inner face of the board, mm;

f _K2 - lateral warpage for the outer layer of the board, mm;

ΔW is the decrease in the average moisture content of wood in relation to the hygroscopicity limit during drying,%. The difference between the hygroscopic moisture limit of the wood W _pg and the final moisture content of the boards W _k after drying, i.e. ΔW = W _pg -W _k ;

and ₂ is the distance from the axis of the log to the right edge of the board, mm;

b ₁ - coordinate of the inner face of the board, corresponding to the distance from the axis of the log to the inner face of the board, mm;

b ₂ - coordinate of the outer surface of the board, corresponding to the distance from the axis of the log to the outer surface of the board, mm;

To _t is the coefficient of wood drying in the tangential direction,%;

To _r is the coefficient of wood drying in the radial direction,%.

The calculation results according to formulas (1) and (2) and experimental data for pine lumber are shown in figure 2 [a) and b)].

The transverse warpage of the inner layer is greater than the outer (Fig. 3), and this is the reason for the appearance of different thicknesses of the board at the edges and in the middle.

The thickness variation across the width of the board, depending on the difference in the coefficients of shrinkage of the layers, is calculated by the formula:

$$R_k=\frac{f_{K2}-f_{K\mathrm{one}}}{S}\cdot \mathrm{one\; hundred}\%,\left(3\right)$$

where P _k is the thickness variation across the width of the board,%;

S is the thickness of the board, mm;

f _K1 - lateral warpage for the inner face of the board, mm;

f _K2 - lateral warpage for the outer layer of the board, mm.

A graph showing the thickness difference of pine boards after drying is shown in FIG. 4.

The amount of lateral warping determines the allowance for machining the board. The component of the machining allowance due to lateral warping is defined as the sum of the warpage values of the inner and outer layers:

$$P=\frac{{\mathrm{<figure-callout\; id="2"\; label="f\; K"\; filenames="00000014.png,00000016.png"\; state="\{\{state\}\}">f\; </figure-callout>}}_K+f_{K\mathrm{one}}}{S}\cdot \mathrm{one\; hundred}\%,\left(\mathrm{four}\right)$$

where P is a component of the allowance for machining due to lateral warping of the board during drying,%;

S is the thickness of the board, mm;

f _K1 - lateral warpage for the inner face of the board, mm;

f _K2 - lateral warpage for the outer layer of the board, mm.

Losses in chips due to warping of boards from pine are shown in the graph (figure 5).

When drying lumber with mechanical restriction of the appearing lateral warpage (by its own weight of the stack or when using clamping devices), additional internal stresses appear in them, the resultant of which (warping force) is calculated by the formula:

$$R_k=\frac{S^2{\mathrm{<figure-callout\; id="0"\; label="E"\; filenames="00000011.png,00000012.png"\; state="\{\{state\}\}">E</figure-callout>}}_0\Delta WL}{3B}\delta \left(\mathrm{one}+\beta \Delta W\right),\left(5\right)$$

where P _k is the warping force of the board, N;

S is the thickness of the cross section of the board, mm;

In - the width of the cross section of the board, mm;

E ₀ is the elastic modulus of the middle layer of the board;

ΔW is the decrease in the average humidity of the board in relation to the hygroscopicity limit,%;

L is the length of the board, m;

δ is the difference between the drying coefficients of the outer and inner layers;

β is the coefficient of influence of humidity on the value of the elastic modulus.

With the same geometric dimensions of the boards (width, thickness, length), the magnitude of their warping strength (and, consequently, additional internal stresses from unacceptable warping) depends only on the difference in the coefficients of shrinkage of the layers, as follows from (5).

The indicator of the difference in the coefficients of shrinkage of the inner and outer faces of the board is determined by the formula:

$$\delta =\frac{K_t-{\mathrm{<figure-callout\; id="2"\; label="K\; r"\; filenames="00000014.png,00000016.png"\; state="\{\{state\}\}">K\; </figure-callout>}}_r}{2}\cdot \frac{x\left(b_2-b_{\mathrm{one}}\right)\left[x^2+2x\left(b_2-b_{\mathrm{one}}\right)-b_{\mathrm{one}}{b}_2\right]}{\left(x^2+{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="00000014.png,00000016.png"\; state="\{\{state\}\}">b</figure-callout>}}_2^2\right)\left(x^2+b_{\mathrm{one}}^2\right)},\left(6\right)$$

where δ is the difference between the drying coefficients of the inner and outer layers of the board,%;

To _t is the coefficient of wood drying in the tangential direction,%;

To _r is the coefficient of wood drying in the radial direction,%;

b ₁ , b ₂ - coordinates of the inner and outer layers of the board, corresponding to the distances from the axis of the log to the inner and outer layers, respectively, mm (see figure 1).

The difference in the coefficients of shrinkage of the plank layers of different widths depending on the coordinates of the inner and outer planks, corresponding to the distances from the axis of the log to the inner and outer planks, respectively, is illustrated in Fig.6 [a) and b)].

, где b₁ и b₂ - координаты внутренней и наружной пластей доски, соответствующие расстояниям от оси бревна до внутренней и наружной пластей соответственно.The difference in the coefficients of shrinkage of the planks at $$\raisebox{1ex}{$b_2$}\!\left/ \!\raisebox{-1ex}{$b_{\mathrm{one}}$}\right.$$

where b ₁ and b ₂ are the coordinates of the inner and outer layers of the board, corresponding to the distances from the axis of the log to the inner and outer layers, respectively.

1 - 10/0; 2 - 20/10; 3 - 30/20; 4 - 40/30; 5 - 50/40; 6 - 60/50;

7 - 45/0; 8 - 55/10; 9 - 65/20; 10 - 75/30; 11 - 85/40.

The mechanical restriction of the lateral warping that occurs during drying (due to the weight of the material in the drying stack or in the case of pressing devices) causes additional tensile stresses to appear on the outer plate in the boards, which causes formation cracks and a decrease in the grade of lumber.

Figure 7 shows a graph of the dependence of the difference in the coefficients of shrinkage of the formations from the width of the formation of the board.

"Cutting off" the upper part of the graph (Fig. 7) with the maximum values of the difference between the coefficients of shrinkage of the layers, find the dimensions and position of the board on the pattern of cutting logs and beams (b ₁ , b ₂ are the coordinates of the inner and outer layers of the board, corresponding to the distances from the axis of the log to inner and outer layers), in which the difference in shrinkage of the layers will be the smallest.

As the boundary point 1, which coincides with the inflection point on the graph δ (x) is selected, a horizontal line 1-2 is drawn through it, cutting off the maximum part of the graph. At values x <x ₁ and x> x _{2, the} difference in the coefficients of shrinkage of the board layers is considered insignificant.

The function of changing the drying coefficient K _x along the width of the board has the form:

$$K_x={\mathrm{<figure-callout\; id="2"\; label="K\; r\; cos"\; filenames="00000014.png,00000016.png"\; state="\{\{state\}\}">K\; </figure-callout>}}_r{\cos }^{}{}^2\theta +{\mathrm{<figure-callout\; id="2"\; label="K\; t\; sin"\; filenames="00000014.png,00000016.png"\; state="\{\{state\}\}">K\; </figure-callout>}}_t{\sin }^{}{}^2\theta +\frac{K_t-{\mathrm{<figure-callout\; id="2"\; label="K\; r"\; filenames="00000014.png,00000016.png"\; state="\{\{state\}\}">K\; </figure-callout>}}_r}{2}\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="00000014.png,00000016.png"\; state="\{\{state\}\}">sin</figure-callout>}2\theta ,\left(7\right)$$

where K _x - the value of the coefficient of drying along the width of the board,%;

K _t is the coefficient of wood drying in the tangential direction,%;

To _r is the coefficient of wood drying in the radial direction,%;

θ is the angle of inclination of the radius vector drawn at the point of interest on the face of the board, to the axis X (figure 1).

The function of the difference in the coefficients of shrinkage of the board layers was obtained using equation (7) for the inner and outer layers in Cartesian coordinates.

The abscissa of point 1 is found by equating to zero the second derivative of the function of the difference in the coefficients of the drying of the layers, and get:

$$3x_{\mathrm{one}}^8-\left(b_{\mathrm{one}}^2+{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="00000014.png,00000016.png"\; state="\{\{state\}\}">b</figure-callout>}}_2^2\right)x_{\mathrm{one}}^6-12b_{\mathrm{one}}^2{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="00000014.png,00000016.png"\; state="\{\{state\}\}">b</figure-callout>}}_2^2{x}_{\mathrm{one}}^{\mathrm{four}}-3b_{\mathrm{one}}^2{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="00000014.png,00000016.png"\; state="\{\{state\}\}">b</figure-callout>}}_2^2\left(b_{\mathrm{one}}^2+{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="00000014.png,00000016.png"\; state="\{\{state\}\}">b</figure-callout>}}_2^2\right)x_{\mathrm{one}}^2+b_{\mathrm{one}}^{\mathrm{four}}{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="00000014.png,00000016.png"\; state="\{\{state\}\}">b</figure-callout>}}_2^{\mathrm{four}}=0\left(8\right)$$

The abscissa of point 2 is calculated from (6) after substituting the value of x ₁ found from (8).

According to the results of calculating the values of x ₁ and x ₂ using equations (6) and (8), a diagram was constructed (Fig. 8). Placing the x ₁ values along the ordinate axis at corresponding distances b ₁ from the log axis to the outer plate surface, draw the upper inclined line, laying the x ₂ values for different b ₂ , similarly draw the lower inclined line, i.e. the ordinates of the points on the lower inclined line are equal to the values of x ₁ (see Fig. 7) obtained by the formula (8); the ordinates of the points on the upper inclined line are equal to the values of x ₂ (see Fig. 7) obtained by the formula (6) taking into account the value of x ₁ calculated above; Right diagram bounded limit value of the distance from the log axis to the outside face of the board, wherein the transverse curl boards during drying to the final humidity W _to respectively 5, 10, 15, 20% will still allowed by the standard board warpage.

Area (2) is limited in the diagram to the right of the vertical line corresponding to the position outside face of the board, in which its transverse curl at the corresponding final humidity W is equal _{to the} standard value allowed by (f _K = 0,01, where B - width up to

boards, mm).

Thus, taking into account the index of the difference in the coefficients of the shrinkage of the board layers, its quality is estimated as a result of drying by the value of transverse warping, by the thickness difference in the direction of its width, by internal stresses due to inadvertent warping and formation cracks resulting from this.

The diagram (Fig. 8) is conventionally divided into three areas.

Region 1 of the diagram above the upper straight line, the ordinates of the points on which are determined from equation (8), characterizes the dimensional parameters (S, B, b ₁ , b ₂ ) of the sawn timber, which will have maximum lateral warping during drying. When drying with pressure, a crack will appear on these boards. All boards have a maximum allowance for machining (due to warping). Region 1 - cracking area.

Region 2 characterizes the dimensional parameters of lumber with the greatest difference in the coefficients of shrinkage of the layers, the greatest warping force. When drying with a clip, all boards will have plastic cracks, while drying without a clip will warp. Region 2 - the area of cracking and warping.

Region 3 to the right of the vertical line with the corresponding final humidity characterizes the dimensional parameters of lumber with high quality drying. On the right, the diagram is limited by a straight line, which corresponds to the distance from the axis of the log to the outer plate of the board (b ₂ ), in which the warping at the corresponding final humidity does not exceed the permissible value in accordance with the existing standard. Due to the slight warpage, the risk of formation cracks and residual stresses is small, the thickness variations along the width of the board and the machining allowance due to warping are negligible.

The claimed method of cutting logs into lumber using the obtained diagram was carried out as follows.

EXAMPLE 1

Sawn larch wood on a sawmill frame. The initial moisture content is above 30%, the diameter of the sawn log D = 30 cm, the length of the log L = 6 m, the cut width is 4 mm, the thickness of the board is 30 mm, the width of the board is 150 mm, and the final humidity is ΔW = 10%. Taking into account the above parameters, using the obtained diagram, favorable zones of the log are predicted during the first pass and timber during the second pass, ensuring the output of lumber with minimal loss of quality during further drying due to warping, cracking and thickness variation, the distance from the log axis to each board is determined its outer layer and choose from the favorable zone of the log the size of the width of each board, characterized by the smallest difference in the coefficients of shrinkage of its inner and outer layers. The first board in the cutting pattern during the first pass of the log (Fig. 9) is a core cut with a thickness of S = 30 mm. The coordinate of the outer layer of the board of the second board with a thickness of 30 mm, taking into account the allowance for shrinkage and cut:

, $${\text{b}}_{\text{2}}^{\text{''}}=\frac{\mathrm{<figure-callout\; id="2"\; label="S"\; filenames="00000014.png,00000016.png"\; state="\{\{state\}\}">S</figure-callout>}}{2}+\frac{\text{<figure-callout id="2" label="Y" filenames="00000014.png,00000016.png" state="{{state}}">Y</figure-callout>}}{2}+{\text{b}}_{\text{P}}+S+\text{Y}=\text{fifteen}+\text{0}\text{,9}+\text{four}+\text{thirty}+\text{one}\text{,8}=\text{51}\text{7 mm}$$

,

where S is the thickness of the board, mm;

Y - allowance for shrinkage by the thickness of the board, mm (the standard value for the given thickness of the board and the final humidity is accepted);

b _P - cut width, mm.

According to the diagram (Fig. 8), the board at b ₂ = 51.7 mm falls into the cracking region (1). When drying, such a board will lower its grade due to formation cracks (when drying with a clamp) or due to excessive lateral warping (when drying without a clamp). The third board has the coordinate of the outer face:

b ₂ = 51.7 + 4 + 30 + 1.8 = 87.5 mm.

According to the diagram (Fig. 8), this board with b ₂ = 87.5 mm and B = 150 mm falls into the favorable region (3), which implies that the quality of this board will not decrease due to lateral warping, formation cracks, residual stress during drying to a final moisture content of 10%. All other boards in the timber during the first pass will not lower their grading due to warping and cracking during drying.

In this case, the smallest thickness variation along the width of the board and the allowance for machining due to lateral warping will be the smallest.

To maintain high quality drying of boards falling into areas (1) and (2) (Fig. 10), it is necessary to provide for them to be longitudinally cut in the middle of the plate, or to cut the beam obtained during the first pass, first in half and then on radial boards (Fig. 10) )

The size of the thickness of the timber (Fig. 10) is determined by the diagram (Fig. 8) taking into account the thickness, width of the boards and their final humidity during drying.

EXAMPLE 2

On the example of a diagram (Fig. 8) for larch wood lumber, diagrams are constructed (Fig. 11) for lumber from other conifers of various thicknesses.

On the right, the diagrams for each thickness of the boards are limited by the final moisture content of the sawn timber during drying, equal to W _K = 5%. The horizontal diagram is divided into 4 equal segments with the corresponding final moisture content (10, 15, 20, 25%) of the lumber (see Fig. 11). For each thickness, the boards (Fig. 11) are presented in the form of separate diagrams, for example, for S = 30 mm (see Fig. 8).

When drying pine boards of various thicknesses, the transverse warping, the thickness difference and the amount of losses during mechanical processing, obtained experimentally, practically coincide with the calculation results. With increasing distance from the axis of the log to the outer layer of the board, the loss of dry lumber due to warpage, thickness variation along the width of the board, due to increased machining allowances decreases (Figs. 3, 4, 5).

In a pine central plank (b ₂ = 40 mm), for example, 40 mm thick and

150 mm wide, when dried to a final moisture content of 10%, the transverse warping of the outer layer is 1.771 mm, the inner layer is 2.647 mm, and their ratio is 1.494. When drying the same board 160 mm wide, this ratio will be 1.456. The known experimental ratio according to [2] is 1.45.

The allowance for machining (due to warping) is in the first case - 11.045%, in the second - 11.89% of the thickness of the board. When placing this board on a log cutting scheme with a new distance from the axis to the outer layer, for example, b ₂ = 80 mm, the losses during machining (Fig. 5) will be reduced from 11.045% to 7.5%. With b ₂ , = 160 mm, the loss will be 4%.

EXAMPLE 3

For boards with a thickness of 60 and 19 mm, the limiting value of the distance from the axis of the log to the outer layer when drying to a final moisture content W _K = 5% is 112 and 65 mm, respectively (Fig. 11). If the distance from the axis of the log to the outer layer of the board with a thickness of 60 mm is less than 112 mm, then a decrease in its quality due to warping and cracking during drying should be predicted. At the same time, boards with a thickness of 19 mm with a lower value of b _{2 will} retain their quality during drying (with b ₂ ≥65 mm). Thus, the yield of high-quality dry lumber can be increased by using the fact that the size of the warping and cracking area in thinner lumber is smaller than in thick lumber when drawing up a scheme for cutting logs and beams. In this example, in the area of warping and cracking (2) of boards with a thickness of 60 mm, it is possible to place boards of 19 mm thickness on the pattern of cutting logs (or beams) of the board with distances to the outer layer in the range from 65 to 112 mm. The combination of different thicknesses of boards when drawing up a scheme for cutting logs and beams using a diagram (Fig. 11) allows to increase the yield of high-quality dry lumber during drying. In this example, 1.72 times.

In the claimed method of cutting logs into sawn timber, forecasting can also be performed using computer programs using mathematical models (6) and (8) to compile computer programs that allow us to evaluate the pattern of cutting logs taking into account the number of possible losses of sawn sawn timber due to defects during subsequent drying.

In contrast to the prototype, in which the shrinkage allowance for the thickness of the board was taken into account as a variable along the radius of the cross section of the log, which resulted in an increase in yield during sawing, this application takes into account unequal shrinkage of the board at different distances from the axis of the log and beam to its outer layer, which allows you to draw up patterns for cutting logs and beams into lumber, during subsequent drying of which the useful yield is increased by reducing the loss of dry lumber due to excessive warping, p cracking, overestimated machining allowances due to thickness variation in width due to lateral warping.

Thus, the invention improves the efficiency of the method of cutting logs by improving the quality of sawn timber due to the implementation of the method of cutting logs, as well as timber, taking into account possible loss of quality of the sawn materials during further drying. As a result, when using the method for cutting logs according to the invention, the yield of high quality lumber is increased, which remains after drying.

Information sources

 1. Yu.R. Bokshanin “Processing and use of larch wood”. - M .: Forest industry, 1973, p. 82-102.

2. V.F. Vetsheva "Cutting large logs into lumber." - M .: Forest industry, 1976.

3. RU No. 2038945, publ. 1995 - a prototype.

Claims (3)

1. A method of cutting logs into lumber, including determining the breed, measuring the diameter of the log, setting the initial and final moisture, setting a pattern for cutting logs as well as lumber, sawing a log into lumber and lumber, and also sawing a lumber into lumber, characterized in that the method They take into account possible losses in the quality of sawn lumber during their further drying, while before assigning a cutting scheme, favorable zones of the log and of the beam are predicted, ensuring the output of lumber from a minimum For each board, the distance from the axis of the log, as well as the beam to its outer layer, is determined for each board by further loss of their quality during further drying due to warping, cracking and thickness, according to which, when assigning the cutting pattern of the log, as well as the beam from the favorable zone, choose the width size each board, characterized by the smallest difference in the coefficients of shrinkage of its inner and outer layers. 2. The method of cutting logs into lumber according to claim 1, characterized in that the prediction can be performed experimentally obtained taking into account the indicator of the difference in the coefficient of drying of the inner and outer layers of the boards with a diagram containing the breed, final moisture, thickness, width of the boards, distance from the axis of the log, as well as the beam, to the outer layer of the board. 3. The method of cutting logs into lumber according to claim 1, characterized in that the forecasting can be performed using computer programs.

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