RU2357054C2 - Composite wooden bar - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention is related to elements of building structures, in particular to composite glued wooden bars intended for application as beams, columns and composite parts of building blocks. Composite glued wooden bar consists of plates joined in groove and comb. Groove and comb are made of wide sides of plates, glue layers between plates are located between tops of combs and bottom of grooves, height of combs exceeds depth of grooves, and width of combs is less than width of their according grooves. Groove and comb on at least some plates have different width that varies from plate to plate according to required profile of bar cross section. Width of grooves is equal to width of plates reduced by value of allowance for finishing treatment. On one side edge of bar there may be additional groove or comb arranged for connection to structural or reinforcing element. In glue layers there are armoring net gaskets laid continuously along the whole length of bar.

EFFECT: cost reduction of timber due to lowering of requirements to quality of initial saw timber and accuracy of their processing prior to gluing.

5 cl, 6 dwg

Description

The proposal relates to elements of building structures, more specifically to composite glued wooden beams intended for use as beams, poles and components of building blocks.

The following terms are used in this proposal.

A beam is sawn, hewn timber, or an glued bag of lumber, the length of which significantly exceeds the other two dimensions.

A beam is a structural element, usually in the form of a beam, working mainly on bending.

The term "face" means the wide flat side of the board, and the term "edge" means the narrow (in thickness) side of the board.

Plate - a board of rectangular cross-section, subjected to additional processing (in this description, milling) before gluing.

In the technique of glued wooden beams, which are plates or boards glued together, the main problem is that the heterogeneity of the properties of wood in different directions, uneven shrinkage, exacerbated by the spread of properties from plate to plate, generate significant mechanical stresses in the bars, leading to disorder of the connection and deformation of the bars. A number of technical solutions to this problem are known.

The second problem is characteristic of mass production, when there are difficulties in providing high-grade lumber used for glued beams. Knives or cracks are not allowed in the plates used to make known glued beams.

A glued wooden element is known, including plates, the fibers of which are oriented along the longitudinal axis of the element, interconnected along flat planed sheets with adhesive layers. The outer plates are made of hard wood (larch, oak, ash), and the inner ones are made of soft (spruce, pine, fir) [RF Patent №2168594, according to cl. Е04С 3/14, declared 12/29/99]. A disadvantage of the known glued element is the high cost due to the use of expensive hard-to-process wood species for the outer plates. As a consequence of the first drawback, such an element cannot be manufactured in quantities that satisfy the needs of mass construction.

Known composite glued wooden beam, including plates assembled in a package, between which adhesive layers are placed, in which, to increase the bearing capacity, the plates are displaced in the package one relative to the other in the transverse direction, forming grooves on the side faces of the beam. The grooves on the side faces formed by the displacement of the plates are filled with composite material (AS USSR No. 956715, according to CL E04C 3/292, decl. 16.12.80). As a composite material, structural plastic with filler from wood chips and sawdust was used.

The disadvantages of the known beams are the inaccuracy of its size and low decorativeness. After curing the composite material, the beam cannot be finished on the side edges in order to finish and give it exact dimensions due to the strong wear of the cutting tool. Depreciation is caused by both the properties of the plastic and the inevitable presence of sand in the waste filler. Another drawback of the known beam is that for its manufacture, high quality wood plates with precisely planed sheets are required.

Known composite glued wooden beam intended for use as a beam, including plates between which adhesive layers are placed, and reinforcing pads made of woven mesh having a variable length along the beam are placed in the support areas of the beam inside the adhesive layers. [A.S. USSR No. 989009, according to class EBB 5/12, claimed 06/08/81]. The use of reinforcing gaskets in adhesive layers increases the strength of the timber or allows it to be made of low-grade material at the same strength. A disadvantage of the known beam is the lack of versatility, due to the fact that the reinforcing elements are placed in the supporting areas of the beam. The location of these zones depends on the structure in which this beam is used, and each structure requires its own beam size. In addition, reinforcing the beam only in the supporting zones does not solve the aforementioned problem of glued wooden beams and beams. Precise processing of the glued beam along the sides on which the adhesive layers with the mesh go out causes rapid wear of the cutting tool. Laying nets in the adhesive layer requires increased attention and accuracy, which makes manufacturing more expensive.

The closest to the proposed beam in terms of technical nature and the achieved result is a wooden board consisting of plates having a longitudinal groove on one edge and a longitudinal ridge on the other, connected by edges so that the crest of one plate fits into the corresponding size groove of the adjacent plate, and the height of the ridge is less than the depth of the groove. Such a connection is called a “groove and comb connection”. The thickness of the crest is usually 1/3 of the thickness of the board, and the height is 1-1.3 thickness of the crest. The thickness of the crest is usually equal to or slightly greater than the width of the groove so that the crest fits into the groove with a slight interference fit (L.N. Kreindlin. Joiner's and carpentry works. - M.: Higher School, 1969, p. 72 and 74). The connection in the groove and comb in its known design is not suitable for the manufacture of glued beams due to the large loss of wood during the milling of the groove and comb. In addition, it requires the use of high-grade lumber because of the requirements for precision processing and the strong dependence of strength on the presence of defects. Such lumber is not only expensive, but also scarce.

The technical result achieved by this proposal is to reduce the cost of timber by reducing the quality requirements of the original lumber and the accuracy of their processing before gluing. This solves the problem of mass production of such bars. In addition, the proposed beam is more technologically advanced, has greater strength and shape stability, its manufacture wears out the cutting tool less.

The specified technical result is achieved by the fact that in a composite wooden beam made of plates connected into a groove and a comb, the groove and comb are made on the wide sides (plates) of the plates, adhesive layers between the plates are located between the tops of the crests and the bottom of the grooves, the height of the crests exceeds the depth of the grooves, and the width of the ridges is less than the width of their corresponding grooves.

In addition, the proposed beam may have a different width of the grooves and ridges on at least part of the plates, varying from plate to plate in accordance with the desired cross-sectional profile of the beam.

In addition, in the proposed beam, the width of the grooves is equal to the width of the plates, reduced by the amount of allowance for finishing.

In addition, at least one side edge of the proposed beam can be made an additional groove or ridge for connection with a structural or reinforcing element.

In addition, in the adhesive layers continuously along the entire length of the beam can be placed reinforcing pads made of mesh.

In addition, the proposed beam is made of the three bars described above, connected in such a way that the edges of the plates of one enter into the grooves on the wide side of the plates of the other two.

In addition, reinforcing pads made of mesh can be continuously placed in the adhesive layers of such a composite beam continuously along its entire length.

The technical result from the fact that the groove and the ridge are made on the wide sides of the plates and the adhesive layers between the plates are located between the tops of the ridges and the bottom of the grooves consists in reducing the cost of the timber by reducing the requirements for the accuracy of processing of the plates, creating the possibility of using low-grade lumber, saving the tool by reducing volume of the removed material.

The technical result from the fact that the adhesive layers between the plates are located between the tops of the ridges and the bottom of the grooves, and the height of the ridges exceeds the depth of the grooves, consists in cheapening the beam by ensuring its strength and shape stability when using uncalibrated non-planed plates from low-grade timber. In addition, when processing the glued beam into the final size, the cutting tool does not work on the adhesive layers, which lengthens its service life.

The technical result from the fact that the width of the ridges is less than the width of the grooves corresponding to them consists in reducing the cost of the beam by simplifying the assembly of the package of plates before gluing.

The technical result from the fact that the proposed beam can have different widths of grooves and ridges on at least a portion of the plates, varying from plate to plate in accordance with the desired cross-sectional profile of the beam, consists in expanding the scope of the beam. When using a beam as a beam, this reduces the consumption of material. It becomes possible to produce bars of various, not only rectangular, profiles with minimal wood consumption. To do this, the width of the protrusions and recesses from plate to plate varies in accordance with the desired cross-sectional profile of the beam.

The technical result from the fact that the width of the grooves is equal to the width of the plates, reduced by the amount of allowance for finishing, consists in saving wood, saving the tool and achieving the greatest strength of the beam. Finishing allowance usually does not exceed the spread across the width of the original boards, and therefore the wood consumption is small. The cutting tool during the finishing processing of the side edges of the beam to the specified size works on clean wood without adhesive layers and reinforcing gaskets. After removing the allowance, the entire width of the beam appears to be occupied by reinforced adhesive layers, that is, the beam, when loaded, works as a monolithic whole.

The technical result from the fact that at least one side edge of the proposed beam has an additional groove or ridge for connection with a structural or reinforcing element, allows you to strengthen the bearing capacity of a beam made of available lumber of relatively small width, and also reduces labor costs for assembly structures using the proposed timber by increasing the accuracy and facilitating its positioning in the structure.

The technical result from the fact that the beam is made of the three bars described above, connected in such a way that the edges of the plates of one fits into the grooves on the wide side of the plates of the other two, consists in reducing the consumption of wood for the manufacture of bars for beams having maximum bending strength with minimum weight .

The technical result from the fact that reinforcing nets from the mesh are continuously placed in the adhesive layers along the entire length of the beam consists in increasing the strength and shape stability of the beam, preventing delamination and other disturbances of adhesive joints, reducing beam warpage due to wood shrinkage, cheaper timber and making it possible its mass production, because it allows the use of affordable low-grade lumber.

The essence of the proposal is illustrated by drawings.

Figure 1 shows the proposed beam before finishing in a given size.

Figure 2 shows a cross section of the proposed beam after finishing.

Figure 3 shows a cross-section of a glued I-beam before finishing.

Figure 4 shows a cross section of another embodiment of a glued I-beam before finishing.

Figure 5 shows the angular connection of two wall panels using the proposed beam for the power frame.

Figure 6 shows a beam for an angular connection, reinforced with an additional plate, positioned by a ridge on the side edge of the beam, before finishing.

The proposed composite wooden beam (figures 1 and 2) consists of glued into a package of wooden plates 1, the fibers of which are oriented along the longitudinal axis of the beam. Between the plates 1 are adhesive layers 2. Inside each of the adhesive layers 2 placed reinforcing pads 3 of the grid. Each of the plates 1 has a groove 4 on one of the plates, and a ridge 5 on the opposite one (Fig. 1). The height h of the ridge 5, the depth b of the groove 4 and the thickness t of the gasket 3 in the compressed state are related by the relation t <b <h + t. When this ratio is fulfilled, the gasket 3 is always completely hidden in the grooves 4, and the ridge 5 always compresses the gasket when assembling the package of plates.

The width B of the grooves 4 and ridges 5 should be equal to or slightly larger than the final width B of the beams in the processed form. The width of the plates before gluing should at least exceed the width B by the amount of machining allowance ΔB, that is, it should be equal to B + ΔB. The height of the glued beam before finishing should exceed the required height of the beam N by the amount of the allowance for processing ΔН, that is, it should be equal to H + ΔH. In order for the upper and lower edges of the timber to be smooth, the machining allowance ΔH must be equal to or greater than the sum of the height h of the protrusion 5 and the depth b of the recess 4. The upper and lower plates of the timber may not have a groove and a crest, respectively, but this increases the range of blanks and complicates the assembly.

The width of the ridges 5 is less than the width of the grooves 4, so that the ridges are guaranteed to fit into the grooves when assembling the package. The numerical value of this difference is determined by the accuracy of the processing of the plates, that is, the maximum, taking into account the tolerance, the width of the ridge should be less than the minimum, taking into account the tolerance, the width of the groove is approximately not less than 0.5 mm.

The width of the reinforcing gaskets 3 is equal to the width of the grooves 4, so that when assembling the bar, the gaskets completely fill the grooves in width.

The need for reinforcing gaskets 3 is determined by the quality of the original lumber and requirements for the strength of the beam.

In order for the adhesive not to be squeezed out when pressing the glued packet of plates, the side walls of the ridges can be made inclined, as shown in callout I of Fig. 1. In this case, the width of the ridge along its apex should ensure that the ridge 5 enters the groove 4, and the width of the ridge 5 at the base should ensure its jamming in the groove 4 in the entire tolerance field.

If the beam should have a width that is variable in height, as shown in Figs. 3-6, then the width of its component plates, ridges and grooves in each of them accordingly changes. In this case, one plate may have a crest and a groove of different widths (Figs. 3, 5 and 6). Allowed a small survey 6 on the part of the plates located outside the grooves and ridges, which will still be removed during finishing (Fig.6).

If the strength of the beam is insufficient and cannot be increased by increasing the width of the plates, or if it is necessary to ensure exact matching of the beam with other structural elements of the building, then at least one side edge of the proposed beam may have an additional groove or ridge for connection with a structural or reinforcing element . Figure 6 shows an example of reinforcing the beam with an additional plate 7, in the groove of which a ridge formed on the side edge of the beam enters. The plate 7 is glued to the beam in the same way as the plates forming the beam are glued together. In this case, the use of mesh reinforcing spacers embedded in the adhesive layer is preferred.

The proposed beam is made as follows.

The original non-planed boards are processed on both layers to obtain ridges and grooves. When calculating the specific sizes h and b, the variation in the sizes of the non-planed boards used for the manufacture of the plates is taken into account, so that the above ratio is always fulfilled. The machining allowance ΔB is always much smaller than the width of the plate, and the wood consumption for combing is very small. The consumption of wood for the formation of grooves is also small, since their depth is close to the thickness of the mesh. For beams of size 150 × 220 mm ^{2, the} wood consumption for the formation of grooves and ridges does not exceed 5%. In the manufacture of known bars of the same size, the usual wood consumption when planing plates on a thicknessing machine reaches 15%. The wear of the tool is approximately proportional to the mass removed when planing wood, and therefore the manufacture of the proposed timber wears the tool 2 ... 3 times less.

Then reinforcing nets are laid in the grooves smeared with glue. Grooves facilitate mesh positioning, which speeds assembly. The plates are collected in a bag (Fig.1, 3 and 4), pressed and dried. To reduce warpage, it is preferable that the plates are collected in a bag with alternately changing the direction of convexity of the original log, as shown in the drawings.

The dried timber blank is processed according to two or more edges to give an exact size and good appearance. So, a rectangular beam (figure 2) can be processed on all four edges. If the beam is used as a corner in the frame of building panels 8 (Fig. 5), then the surface adjacent to the structural insulation 9 of the panel is not processed after gluing. When planing the side edges of the timber (along the edges of the plates), the depth of planing does not exceed half of the allowance for processing ΔB so that the tool does not touch the adhesive layer and grids (figure 2 and figure 5).

Due to the fact that the surfaces to be glued are not planed, the villi and burrs remaining after sawing the logs additionally reinforce the adhesive joint. The reinforcing effect of the mesh and villi allows local increases in the thickness of the adhesive layer without reducing the strength characteristics of the timber. This avoids the processing of plates on a thicknessing machine, which significantly reduces the cost of production. All this also reduces the requirements for the quality of the material of the plates, and the proposed beam has the same strength characteristics as the well-known glued beams of the same size, but with a grade of material one or two units lower. Due to the above advantages and reducing the cost of regrinding a cutting tool for finishing, the proposed composite beam is obtained in production no more than glued timber without nets, but it is better in quality.

Claims (5)

1. Composite wooden beam made of plates connected into a groove and a ridge, characterized in that the groove and the ridge are made on the wide sides of the plates, adhesive layers between the plates are located between the tops of the ridges and the bottom of the grooves, the height of the ridges exceeds the depth of the grooves, the width of the ridges is less than the width of the corresponding grooves, and in the adhesive layers between the bars continuously along the entire length of the beam placed reinforcing pads of mesh. 2. Composite wooden beam according to claim 1, characterized in that the groove and the ridge on at least part of the plates have different widths, varying from plate to plate in accordance with the desired cross-sectional profile of the beam. 3. Composite wooden beam according to claim 1, characterized in that the width of the grooves is equal to the width of the plates, reduced by the amount of allowance for finishing. 4. The composite wooden beam according to claim 1, characterized in that on at least one of its lateral edges an additional groove or ridge is made for connection with a structural or reinforcing element. 5. A composite wooden beam composed of three bars according to claims 1 and 3, characterized in that the edges of the plates of one enter into the grooves on the wide side of the plates of the other two.

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