LT7119B - GLUED DOUBLE BEAM - Google Patents

Abstract

The subject of this invention is a two-beam, all structural elements of which - horizontal upper and lower strips (1, 2) and vertical middle connecting strip (3) - are made of plywood. A new solution is used to connect all structural elements of the two-beam into a whole, where the middle connecting strip of the two-beam (3) has a plurality of teeth (4) of rectangular cross-section, formed on both edges of the strip (3) along its entire length, and the upper and lower strips of the two-beam (1, 2) have a plurality of rectangular holes (5) on their side surfaces, corresponding to the shape and position of the cross-section of the teeth (4) of the middle connecting strip (3), formed along the middle of each upper and lower strip (1, 2) of the two-beam. The two-beam beam of the present invention is obtained by inserting the middle connecting strip (3) with its teeth (4) into the corresponding rectangular cross-section cutouts (5) in the upper and lower strips (1, 2), having previously lubricated the edges of the middle connecting strip (3) with the teeth (4) with glue. Additionally, the mutual connection of all three constituent elements of the two-beam beam can be reinforced with wood screws (6) screwed through the side surfaces of the upper and lower strips (1, 2) into the edge of the middle connecting strip (3).

Description

TECHNICAL FIELD

The invention relates to two-beams made of glued plywood for use in the construction industry, in particular in the construction of frame buildings, using the two-beams of this invention as rafters or beams and/or other structural building elements.

STATE OF THE ART

In the construction industry, when it is necessary to withstand loads, especially those applied in one direction, and in order to reduce the cost and weight of the material, two-span beams are used. A two-span beam is characterized by the fact that it consists of an upper and lower horizontal flanges, connected to each other by a vertical strip running along the entire length of the flanges. Beams of this design have high resistance to loads applied to beams mounted on supports, for example, when they are used as rafters or floor elements. The width of the upper and lower flanges gives the beam the necessary lateral rigidity, so it is possible to use a narrow vertical strip connecting the flanges. Under the same ultimate loads, such a two-span beam is advantageously lighter than a solid beam of rectangular cross-section.

One of the variants of realization of a wooden double-beam is described in the Russian patent No. RU2454516. The double-beam consists of horizontal upper and lower wooden strips and a vertical plywood wall connecting these horizontal wooden strips. The vertical plywood wall is fixed in the longitudinal grooves of the wooden strips by pins made of round pipe profiles.

Another embodiment of a two-beam beam is described in US patent application No. US4191000. A two-beam beam consists of two solid elongated wooden strips of rectangular cross-section, glued to opposite edges of a vertical plywood strip. The subject of the invention is the configuration of the connection between the wooden strips and the edges of the plywood, which forms a solid connection between all elements of the two-beam beam. Each wooden strip has a pair of longitudinally oriented parallel grooves, and the vertical connecting plywood strip has correspondingly shaped edges. All elements are interconnected by glue, obtaining a two-beam beam having an increased area of the connecting contact area.

Both of the above-mentioned inventions have in common that the two-beam beams consist of structurally different elements: the upper and lower flanges and strips of the beams are made of wood, and the vertical connecting element is made of plywood. The vertical connecting element is fixed by an adhesive connection in longitudinal grooves cut in the upper and lower flanges or strips.

ESSENCE OF THE INVENTION

The object of the present invention is an alternative beam, differing from the above-mentioned known solutions, first of all, in that all its structural elements - the horizontal upper and lower strips and the vertical middle connecting strip - are made of the same material, namely plywood. In addition, a new solution is used to connect all the structural elements of the beam into a whole, where the middle connecting strip of the beam has a plurality of teeth of rectangular cross-section, formed on both its edges along the entire length of the middle strip, and the upper and lower strips of the beam have a plurality of rectangular holes on their side surfaces, corresponding to the cross-sectional shape of the teeth of the middle strip of the beam, formed along the middle of each upper and lower strip of the beam.

The two-beam beam of this invention is obtained by inserting the vertical middle connecting strip of the two-beam beam with its teeth into the corresponding rectangular cross-section cutouts in the horizontal upper and lower strips, after having previously lubricated the edges of the middle strip with the teeth with glue. Additionally, the mutual connection of all three constituent elements of the two-beam beam can be reinforced with wood screws screwed through the side surfaces of the upper and lower strips into the edge of the middle connecting strip.

DESCRIPTION OF DRAWINGS

The invention is described below with reference to the accompanying drawings, in which:

Fig. is a perspective view of a two-beam beam of the present invention;

Fig. is a side view of the constituent elements of the two-beam of the present invention;

Fig. 1 is a side view of an assembled double-beam of the present invention;

Fig. 1 shows a view of an embodiment of a two-beam beam of this invention, which has additional elements for fastening the constituent elements of the beam together.

DETAILED DESCRIPTION OF THE INVENTION

As shown in Fig. 1, the two-beam of the present invention consists of an upper strip 1, a lower strip 2, which are parallel to each other, and a vertical middle connecting strip 3, arranged between the upper and lower strips perpendicular to their surfaces. All the constituent elements of the two-beam are made of plywood, the thickness of which in the best embodiment of the invention is not less than 12 mm. The width of the upper and lower strips 1, 2 may be in the range between 95 mm and 200 mm, and the width of the middle connecting strip may vary from 100 mm to 1000 mm.

Fig. shows side views of individual components of the two-beam beam of the present invention. The middle connecting strip 3 of the two-beam beam has a number of teeth 4 formed on both longitudinal edges of the strip 3. The teeth are of rectangular cross-section, their length is about 50 mm, the depth of the teeth 4 corresponds to the thickness of the plywood from which all the components of the two-beam beam are made, they are arranged along the entire length of the strip 3 with a distance of 200 mm from each other.

The upper and lower strips 1 and 2 each have a plurality of rectangular cross-section slots 5, made along each strip through their middle and arranged so as to coincide with the teeth 4 of the middle connecting strip 3. The dimensions of the rectangular slots 5 correspond with a small tolerance to the dimensions of the teeth 4 of the middle strip 3. This tolerance is necessary so that the teeth of the middle strip can enter the slots 5 of the upper and lower strips 1,2 with a small interference fit.

The two-beam beam is assembled in the following way: the edges of the middle connecting strip 3 with the teeth 4 are smeared with glue. The choice of glue is not limited, it can be any wood glue, in the best case - polyurethane-based glue. Then the upper and lower strips 1, 2 are connected to the middle connecting strip 3, by inserting the teeth 4 on one edge of the middle connecting strip 3 into the notches 5 of the upper strip 1, and the teeth 4 on the opposite edge of the middle connecting strip 3 into the corresponding notches 5 of the lower strip 2. After the glue hardens, a glued plywood two-beam beam of this invention is obtained, the side view of which is presented in Fig. 3, and the general view - in Fig. 1.

According to yet another embodiment of the present invention, the assembled two-beam beam can be additionally reinforced with wood screws 6, screwed through the side surfaces of the upper and lower strips 1, 2 into the edge of the middle connecting strip 3, resulting in a two-beam beam, shown in Figure 4. In the optimal case, the smallest diameter of the wood screws used is 4.5 mm, and the length is three times greater than the thickness of the plywood of the two-beam beam.

During testing, it was found that the glued two-ply plywood beam of this invention is not inferior in strength and load resistance parameters to beams made of solid wood, but is more useful in that it is significantly lighter and more economical.

Claims (6)

DEFINITION OF THE INVENTION 1. A glued double-sided beam made of wood, comprising upper and lower horizontal strips and a middle vertical connecting strip, characterized in that a) the middle connecting strip (3) of the double-beam has a plurality of teeth (4) of rectangular cross-section formed on both edges of the middle connecting strip (3) along its entire length, b) the upper and lower strips (1, 2) of the double-beam have a plurality of rectangular cross-section cutouts (5) formed along the upper and lower strips (1, 2) of each double-beam through their middle, corresponding to the shape and position of the cross-section of the teeth (4) of the middle connecting strip (3) of the double-beam, the dimensions of the rectangular cross-section cutouts (5) of these upper and lower strips (1, 2) correspond with a small tolerance to the dimensions of the rectangular cross-section teeth (4) of the middle connecting strip (3), both - the upper and lower - strips (1, 2) are glued to the middle connecting strip (3) by teeth (4) entering into the corresponding cutouts (5) in the upper and lower strips (1, 2). 2. A two-beam beam according to claim 1, characterized in that the width of the upper and lower strips (1, 2) is within the limits of 95 mm and 200 mm. 3. A two-beam beam according to claim 1, characterized in that the width of the middle connecting strip (3) is in the range from 100 mm to 1000 mm. 4. A two-beam beam according to claim 1, characterized in that the length of the teeth (4) of the middle connecting strip (3) is about 50 mm, the depth of the teeth (4) corresponds to the thickness of the upper and lower two-beam strips (1, 2), the teeth (4) are arranged along the entire length of the middle connecting strip (3) with a distance of 200 mm from each other. 5. A two-beam beam according to claim 1, characterized in that it has additional fastening elements for its constituent elements - wood screws (6), screwed through the side surfaces of the upper and lower strips (1,2) into the edge of the middle connecting strip (3). 6. A two-beam beam according to any preceding claim, characterized in that it is made of glued plywood with a thickness of at least 12 mm.