RU2045387C1 - Method of cutting out logs of foliate trees - Google Patents

Abstract

FIELD: timber procession. SUBSTANCE: method comprises steps of forming in a log deep longitudinal radial saw cuts, being used together with formed parts, having trapezoidal cross section, as ducts for ventilation and for accelerating drying process; packing sets of block-blanks, having rectilinear cross section, from the trapezoidal parts, turned out by 180 degrees one relative to another. EFFECT: enhanced quality of wooden articles of raw material. 2 cl, 29 dwg

Description

 The invention relates to woodworking, in particular to the field of cutting wood raw materials, ensuring the preservation of the biological and physico-mechanical properties of wood, increasing its useful yield, especially with fine-grained raw materials, the input of the plots for gluing blocks-blanks going to the manufacture of products or parts with rigid limitations of their warping during operation.

 As a prototype of the ridge cutting method, a method is adopted to improve the quality of wood by cutting the ridge on a thin board, from which logs are glued into blocks intended for the manufacture of products, which are required to have a minimum tendency to warp (deformation) of FIGS. 20 and 21.

 The peculiarity of the properties of birch wood, as the most common type of raw material of hardwood.

 Before assessing the disadvantages of the prototype, you should give a brief description of the birch, as raw materials suitable for the production of many types of products with high physical and mechanical performance properties (for example, skiing). Healthy birch wood fully meets these requirements: flexibility, elasticity, sufficient viscosity and a number of other useful properties.

However, birch, as a tree species, has a number of specific features:
a) The bark of a birch bark tree does not let air through, and therefore, from the moment of cessation of activity (after cutting), the inner layers of wood are prone to suffocation, which manifests itself in the intensive development of microorganisms and microflora (fungi). Outwardly, this is expressed in the appearance of colored colors (red, blue), and qualitatively in a sharp decrease in physical and mechanical parameters: bending strength, ductility, pronounced fragility and tendency to crack.

 b) The birch at the growth inlet, being sun-loving, is characterized by a twisted direction of the fibers in the trunk, i.e. their location in a spiral (in the direction of the sun) Fig.28, this manifests itself in the form of a cross-layer in lumber, despite full adherence to the technology of cutting ridges with the orientation of the sheets of bars in the tangential direction. This is especially clearly seen in the production of massive skis, when during drying of paired bars, with a preliminary deflection towards the boggy side, the mentioned feature of the birch trunk structure causes warping of the dried bar-blank (Fig. 19), which during subsequent mechanical processing (planing on the face ) leads to the appearance of a cross-layer, especially at the end sections of the disc (Fig. 25). This inevitably leads to a break both during bending of the toe and during the operation of the skis (in the toe and heel).

 Based on the above characteristics of birch as a breed, the influence of its properties on products, it becomes clearer to preserve its quality indicators at all stages of processing.

 In terms of preventing suffocation. The main recommended measure is squeezing the ridge (Fig.27). The operation is labor-intensive, performed manually, and therefore practically not carried out, i.e. predetermining the receipt of industrially knowingly low-quality, and often practically unsuitable for processing raw materials.

 In terms of improving (optimizing) the structural properties of wood. Sawing the ridge into thin semi-finished material (Figs. 20 and 21), followed by cutting into plots going for gluing into blank blocks with acceleration of the direction of the annual layers. In principle, the goal of averaging the quality of wood by mechanical indicators is achieved by the probabilistic principle of multidirectional deformation of individual plots (Fig. 22). However, with this technology, along with a significant loss of wood for allowances for planing, there is a loss of a significant part of sapwood (the most valuable in terms of mechanical indicators) wood (Figs. 20, 21, 24, 25, 26).

The disadvantages of the prototype:
a) Significant wood waste both during culling (mainly knots) and (especially) during processing (planing) in order to eliminate the consequences of deformation of logging blanks as a result of drying (Figs. 24, 25, 26). Under the conditions of obtaining blocks in the full length of the ridge from thin plots (with a thickness of about 20 mm), the useful yield of wood will be 25-30% (of the round timber), and taking into account additional blocks of small length, the useful yield of wood increases, but does not exceed 40-45 % even under optimal process conditions.

 b) Significant loss of sapwood in the wake, thin croaker, shallow quartet, etc.

 c) Significant residual internal stresses in the wood arising during drying with forced technological measures to maintain the correct geometric shape of the dried lumber (frequent laying, stack load, etc.).

The purpose of the invention:
1. Cutting the ridge, taking into account the biology of the development of the tree (radial arrangement of knots in the trunk), which makes it possible to more efficiently turn off defective (knots) of wood during processing, providing an optimal useful yield of long workpieces, in comparison with traditional technology.

 2. The use of the most healthy with high mechanical properties of sapwood.

 3. Preservation of the biophysical properties of wood (especially birch), starting from the earliest phases of the technological process, by ensuring effective ventilation of the deep layers of the round timber (ridge).

 4. The stability of the geometric shape of both the semi-finished product (glued block-blank), and parts and products made from it.

 5. An increase in the useful yield of wood from the ridge by reducing its losses when cutting into sawdust and shavings.

 6. The ability to effectively use as a raw material a fine round log, which is disadvantageous for traditional processing technology.

Ways to solve the problem:
the formation from the ridge of plots of a wedge-shaped section (trapezoidal shape) of Figures 10, 11, with the orientation of the wide (sapwood) and narrow (core, core) edges strictly tangential, and the layers in the radial direction relative to the cross section of the ridge, by performing radial cuts (Fig. 1, 2), which leads to a specific trapezoidal shape of their section;
providing ventilation of the deep layers of wood using cuts made with the aim of forming plots, thereby ensuring complete preservation of the quality of wood (figure 1);
reducing to a minimum the number of technological transitions associated with planing "as clean" (only sapwood and core edges) of figure 10, and, limited only by grinding when processing the surfaces of the plots of plots (figure 11);
the formation of blocks of rectangular cross-section unfolding around the longitudinal axis of each second plot of 180 ^about (Fig).

 In FIG. 1 shows the implementation of radial cuts, taking into account the location of the main type of defect (knots); figure 2 diagram of the technology for executing cuts; on figa variant of the scheme for cutting dried ridge into sector blanks, convenient for further processing; on figb sector blanks in a disconnected form; in Fig.4 the technology of dividing the ridge into sector blanks using a variant of the supporting guide ridge; figure 5 option of cutting sector blanks into separate plots; figure 6 diagram of the destruction of the ridge under the action of internal stresses as a result of changes in the volume of wood at a moisture content below 30% abs. Fig. 7 is a cross section of the ridge after making cuts: in the upper half of the figure immediately after machining, in the lower half of the figure after drying (increasing and changing the shape of cuts). On sector "A", arrows indicate the direction of deformation in the radial direction, on sector "B" the tangential direction of deformation; on Fig the nature of the deformation and possible destruction of sectors along the ridge as a result of wood drying; in Fig.9 blanching of the sawn ridge in order to avoid the occurrence of drying cracks; figure 10 diagram of the processing of the edges of the plot planing "as clean"; 11 is a diagram of the processing of plots of the plots by grinding "as clean". Possible longitudinal deformation of the plot as a result of uneven drying during a decrease in wood moisture is shown; in FIG. 12a. b grade block from plots when gluing; a) the relative position of the deformed plots (in length) before compression; b) elimination of the longitudinal deformation of the plots after compression and subsequent drying, fixing the necessary geometric shape of the block; in Fig.13 the shape of the block glued from the plots taking into account their availability; Fig. 14 is a diagram of the deformation of shields (carving boards, icons, etc.) reinforced by wedges made of qualitatively seasoned wood, a long time after their manufacture, as a result of the manifestation of residual internal stresses due to drying; on figa, b, in cutting the ridge on the bars with the tangential orientation of the layers in various ways, taking into account the diameter of the ridge; in Fig.16 cutting a thick ridge with obtaining a beam from round timber, a half-beam from a thick slab and blanks from quarters of a slab; on Fig open ridge on the workpiece by the method according to ed. St. N 90906, CL 38a, 5, 1950; on Fig deformation of the cross section of the bar (boards, plots) during drying during the tangential orientation of the layers, plot A in Fig.20, 21; on Fig deformation of the bar (boards, plots) of fuzzy orientation of the layers mixed radial tangential, which causes twisting of the workpiece propeller (wing), plot B in Fig.20, 21; on Fig open cutting ridged (direct dissolution on the unedged board) for subsequent cutting into plots; in Fig.21 open the ridge on the beam, then used to obtain plots with the tangential orientation of their layers, and two options for cutting the slabs on the plots; on Fig complete set of plots in the block blank; on Fig illustration of the statement about the impossibility of using plots with the tangential orientation of the layers deformed during drying, for gluing directly without planing the layers; Fig.24 elimination of deformation of plots during drying (with the tangential orientation of the formations). The shaded areas are wood that goes into shavings; on Fig elimination of deformation of plots with an uncertain orientation of the layers (prone to wingedness) by planing. The unshaded section of the useful wood yield section; in Fig.26 longitudinal deformation of the beam (board) on the face towards sapwood during drying; on Fig squeezing flats on a birch ridge to prevent suffocation of wood after cutting the tree; in Fig.28 a spiral arrangement of wood fibers (twisting), leading to a cross-slab in the blanks (timber, board, plot); on Fig trapezoidal shape of the plot in a cooperage, not having a qualitative relationship to the trapezoidal shape of the plot obtained according to the proposed method.

 Prerequisites that determine the appropriateness of the application of the proposed method. The geometric shape of the cross section of the tree trunk (circle) determines that its peripheral zones undergo significant stretching during drying. This is compounded by the fact that the coefficient of drying of sapwood (as younger) is greater than this indicator for sound (core) wood. A manifestation of this feature are radial cracks of various depths extending from the periphery to the center (Fig.6).

 Radial cuts (Fig. 7 I) play the role of cracks unloading wood in sectors (plots) from internal stresses arising during drying in the tangential direction (Fig. 7 II, sector "B") providing a "painless" intensification of the drying process. As a result, there is a change in the configuration of the sectors (Fig. 7 II), where the dotted line shows the initial view of the cut and the sectors of wet wood, and a solid line of dried wood. On sector "A", the arrows show the direction of shrinkage in the radial direction, which also flows unhindered.

 The difference in the drying coefficients of sapwood and core wood also affects in the longitudinal direction, expressed in the tendency of the wood to warp (bend) towards the sapwood (Fig. 9) with the risk of cracks at the ends. This is partly due to the accelerated drying of the end sections of the ridge. With radial cuts, the width of the edges of future plots (distance between cuts) in the central (deep part of the ridge) will be less than along the perimeter, and therefore, the occurrence of cracks in these places is most likely. This determines the need for screeding the ends of the ridge with elastic clamps (Fig. 9).

 The biological polymorphism of the structure of wood causes local deviations of its properties, manifested in the form of uneven shrinkage both in magnitude and direction, and therefore, the straightness of the sector along the length is not guaranteed (Fig. 11). However, such deformations occur when the moisture content of wood is significantly lower than 30% abs. when moisture in the walls of wood tiles is actively removed.

 Description of the method. After felling the tree, bucking is performed by transverse cutting of whips into short segments of a certain length (usually 2-2.5 m).

 Ridge is fixed in the centers of a special machine and deep cuts are applied along it, which are located radially relative to the cross section of the ridge, allowing a change in the angle of rotation of the ridge within certain limits (Figs. 1 and 2) in order to rationally turn off wood with defects (mainly knots). This operation is the first phase of the formation of future plots of trapezoidal shape with a strict orientation of the edges in the tangential direction and the radial layers. Sectors with defects are subsequently transversely cut to remove defective areas of wood and produce shorter plots.

Saws in the ridge solve the following issues:
create conditions for effective ventilation of the deep layers of the wood of the ridge, eliminating its choking and preventing the development of micro- and mycoflora, thereby ensuring the complete preservation of the high physical and mechanical properties of wood;
accelerate the process of natural and artificial drying in an intensive mode without fear of cracking of wood;
allow you to apply the method of drying currents of industrial frequency according to ed. 115382 (method of drying products from non-conductive material).

 Since wood is prone to warping when humidity drops below 30% deform, bend in the direction of sapwood (Fig. 8) with the danger of cracking shrinkage (Fig. 8), the screed is tightened near the ends with bandages (Fig. 9). The ridge prepared in this way is stored by the cages until transported or processed in the workshop.

 In the case of subsequent gluing of plots into blocks with water-based adhesives (PVA, carpentry bone or mezdrovy, casein, etc.), it is advisable to carry out further cutting of the ridge at a wood moisture content of 22-25% when deformations of sectors on the formation (Fig. 11) appear even in small degrees and can be suppressed during crimping after gluing and subsequent drying of the blocks in the clamped state to operating humidity (12-15%) or to intermediate humidity (18-20%) of the blank blocks going to the 2nd gluing stage (e.g. in the production of hard-glued skis).

 Sufficiently dried ridge is divided into 2-3 sector blanks (Figs. 3 and 4), after which the plots are separated from the central rod (Fig. 5).

 The edges of the plots are cut “as clean” (Fig. 10) without eliminating the fallout.

 The plots of the plots are ground to eliminate the marks left by the saw (Fig. 11). At a wood moisture content of 22-25% by grinding, the pile is not eliminated, which is not required, since it strengthens the adhesive bond. The longitudinal warpage of the plots at the indicated humidity is negligible and does not require elimination by planing, which is associated with the loss of wood in the chips. Crimping when gluing is enough.

 For the correct difference in the methods of developing raw materials and assessing the advantages of the proposed method (in comparison with traditional ones), it is necessary to describe in more detail the negative aspects of the technology of the prototype method, which were not included in the section "Disadvantages of the prototype" and are characterized there by the general phrase "large waste of wood into chips."

 The need to include in the technology transitions "planing on the face" and the associated allowances (and, consequently, the loss of wood) is determined by the variation in the orientation of the layers obtained by the plots when cutting the ridge (Fig.20 and 21). If the plots of type "B" plots are oriented radially (as in the proposed method), then the type "A" plots are deformed during drying in the longitudinal direction (Fig. 26) and in the transverse "trough" (Fig. 18). Getting rid of the last kind of warpage by crimping during bonding will cause cracks (Fig. 23). So inevitably there is a need for an allowance for thickness, since in particular planing machines of the jointer type are not suitable for gouging curves (along the length of the layers of FIG. 26). Plots of type "B" of mixed radial tangential orientation due to the presence in them of all types of warping, including "wingedness" (Fig. 19), lead to a particularly low useful yield of wood (Fig. 25).

 The biological feature of the growth of knots (in the radial direction) also increases the amount of wood going to waste when cutting the ridge, both into a collapse on an unedged board (Fig. 20), and with the preliminary receipt of a beam trimmed plots (Fig. 21).

 Special Explanations. Wood is a durable material with very specific properties. Even with slight fluctuations in the humidity of the air, under generally favorable conditions, wood products tend to deform in its natural directions, despite all the measures taken: long-term drying and aging of workpieces, strengthening of wooden substrates (boards, shields, icons and carvings) with oak strong wedges (Fig.14).

 The proposed method of orienting sapwood and core wood in plots and their opposite position relative to each other do not eliminate the process of slow deformation during the natural removal of internal residual stresses in each plot. However, the antidirectionality of the process of deformation of wood in individual plots provides minimal distortion of the initial geometric shape of the product as a whole.

Regarding some objections raised by experts in their decisions of 1957-58. and in order to anticipate possible objections, the following should be noted:
a) Indeed, the trapezoidal cross-sectional shape of the workpiece is obtained by the method according to ed. St. N 90806, CL 38a, 5, 1950 (Fig. 17). But the technology of "deploying the ridge" is both complex and heterogeneous, having variable equipment settings for each subsequent sawn blank. In addition, this technology does not solve the problem of the minimal influence of knots on the useful yield of wood, since the blanks are “turned” to the knots with wide layers.

 b) The trapezoidal shape of the plots (rivets) of the barrel in the cooper production is determined by the shape of the barrel in cross section (in the form of a circle in Fig. 29), where one rivet is highlighted in bold. However, this similarity is purely external. There are no specific requirements for the rigid orientation of sapwood and core wood relative to the riveting layers, since the overwhelming majority of barrel containers are operated in conditions of wood humidity over 30% when there is no warping process.

 c) A possible objection by experts that there is no positive effect due to the large amount of poorly mechanized labor (an individual approach to cutting the ridge, making radial longitudinal cuts, the collapse of the dried ridge into blank sectors, bandaging of the end sections of ridges, etc.) cannot be taken into account , since a sharp increase in the price of raw materials makes the need to achieve the maximum useful yield of wood through a differentiated approach to cutting each ridge divided nki and rational use of each plot.

Claims (2)

 1. METHOD FOR OPENING A DECK OF DECIDUOUS BIRDS, including the formation of plots of trapezoidal section by making radial cuts of constant depth along the entire length of the ridge and separating the plots from the central core, characterized in that the radial cuts are performed to a depth of the core layer of wood, then the ridge is screed in the zone ends and dry it, after which the ridge is divided into sectorial blanks and the plots are separated. 2. The method according to p. 1, characterized in that the separated plots are rotated 180 ^o around their longitudinal axis by combining the vertex ends with the vertex, and the butt with the butt to form semi-finished blocks.