METHOD FOR JOINING BEAMS MADE OF WOOD-BASED MATERIAL

Description

[0001] The invention relates to a method for joining beams made of solid wood or glued wood.

[0002] Common connectors for solid wood or glued-laminated timber beams, which can be used for connections subject to both compression and tension loads, consist of metal plates inserted into prefabricated slots in one or more beams. The metal plates have through holes. After the steel plates are inserted, they are secured in the beams with dowels, which are usually also made of steel. This requires drilling into the beams, which is difficult to achieve due to the precise alignment of the holes in the steel plates.

[0003] German patent DE 197 24 285 C2 describes a connector for beams made of solid wood or glued laminated timber that uses non-pre-drilled steel plates. Special dowels with a drilled section at their tip are used to secure the steel plates. These dowels can penetrate both the beam and the steel plate.

[0004] German patent DE 862 659 B discloses a rod connection for timber trusses using node plates, in which the node plates are made of pressed synthetic wood. When assembling a truss, node plates made of a more easily workable material, such as plywood or hardboard, are inserted instead of the final node plates. After drilling, these are used as templates for the final node plates. The pre-drilled node plates made of pressed synthetic wood are then inserted into slots in the truss members to be connected. Both the truss members and the node plates are then pre-drilled, and dowels are inserted into the pre-drilled holes. Care should be taken to ensure that the hole diameter in the node plates is slightly larger than the hole diameter in the truss members.

[0005] German utility model DE 296 21 923 U1 discloses a special screw for connecting beams made of solid wood or glued wood to a gusset plate. The gusset plate is inserted into a slot in the beam, and the special screw has a drill bit with lateral drilling wings that are provided with predetermined breaking points with the screw shaft. In addition, the special screw has a thread with a first, smaller outer diameter in a first section adjacent to the drill bit. In a second section, starting from the head of the screw, the screw has a thread with a second, larger outer diameter. The length of the two sections with the smaller and larger outer diameters is precisely coordinated so that the section with the external thread with the larger outer diameter only engages the wooden beam once the drill bit has completely drilled through the gusset plate.After drilling through the gusset plate and when the drill bit penetrates the drilled hole in the gusset plate, the two lateral drill wings shear off on the screw shaft. After penetrating the gusset plate, the drill bit consequently drills a hole with a smaller diameter, which is then matched to the external thread with the smaller outer diameter.

[0006] Swiss patent CH 680 674 A5 discloses a corrugated sheet-wood connection for holding wooden beams together at the ends or in a T-shape, using tension and shear. Slotted blind holes are drilled into the wooden beams, into which a connecting sheet is inserted. Nails or screws are driven into the beams and the sheet perpendicular to the connecting sheet without pre-drilling. The sheet thickness is kept small enough to allow nails or screws to penetrate the hole-free sheet.

[0007] The invention is intended to provide an improved method for joining beams made of wood-based material.

[0008] The problem underlying the invention is solved by a method for connecting beams made of solid wood or glued wood with the features of claim 1. The following steps are provided: creating slots in the beams, inserting a connector made of synthetic resin-filled compressed wood into the slots, and fixing the connector in the slots using wood screws. The particular advantage of the method according to the invention is that the connectors do not have to be pre-drilled. Rather, when erecting a wooden structure, a carpenter can pre-drill the beams with the connectors inserted into the slots of the beam using conventional wood drills and then insert wood screws. The method according to the invention is particularly advantageous when the connectors are fixed in the slots of the beams using wood screws.In such a case, conventional wood screws can be used and, in particular, no pre-drilling of the beam or the connector is required.

[0009] According to the invention, the wood screws are screwed into the beams and the connector without pre-drilling the beams and the connector.

[0010] It is advantageous to use wood screws with a drill tip.

[0011] In this way, even the connectors made of very hard and durable resin-based compressed wood can be penetrated using the wood screws without pre-drilling.

[0012] According to the invention, wood screws with full thread are used.

[0013] Using wood screws with full thread, the connectors can be fixed in all directions of movement.

[0014] A connector set for beams made of wood-based material, in particular for connections subject to both compressive and tensile loads, is provided, wherein the connector set comprises at least one connector with at least one plate-shaped section for insertion into prefabricated slots in the beam or beams, wherein at least the plate-shaped section of the connector consists of synthetic resin compressed wood, wherein the synthetic resin compressed wood consists of several superimposed hardwood layers and synthetic resin, and wherein the connector set comprises several wood screws which are provided for fixing the at least one connector in the beam.

[0015] Surprisingly, it is now possible to replace the conventional metal plates, such as steel or aluminum plates, in beam connectors with plates made of synthetic resin-compressed wood. Such synthetic resin-compressed wood plates can be processed with wood tools and can also be drilled through using wood screws. In this way, it is possible to fix a non-pre-drilled connector plate made of synthetic resin-compressed wood to a beam using wood screws. This completely eliminates the cumbersome connection of drilling templates or special drill bits for steel, which had to be used previously. Surprisingly, it has been found that connectors made of synthetic resin-compressed wood can easily withstand the loads encountered when connecting beams in timber construction. This is especially true when a beam connection is subject to both compressive and tensile loads. A further advantage of the invention arises with regard to fire safety.The known disadvantages of steel connectors do not occur with connectors made of resin-coated wood. Within the scope of the invention, several connectors can be inserted into slots arranged parallel to one another.

[0016] The multiple wood screws can each have a drill bit.

[0017] Because the wood screws are equipped with a drill bit, even the connector made of very hard and difficult to penetrate resin-based compressed wood can be penetrated without any problem.

[0018] The wood screws are designed as full thread screws.

[0019] The plate-shaped section can be rectangular or T-shaped. Using the resin-coated wood connectors according to the invention, the shapes commonly used for steel plate connectors can be easily produced. Existing tools can therefore be easily reused for creating the slots in the beams.

[0020] The synthetic resin can be a thermosetting resin. Resin-based plywood consists of several hardwood layers bonded together with a thermosetting or thermosetting resin, which can no longer be deformed after curing. The resin may also penetrate the layers. This results in a very stable and highly resilient composite.

[0021] The tensile strength of the resin-based pressed wood used is advantageously greater than 75 N / mm 2 parallel to the hardwood layers. The compressive strength parallel to the hardwood layers is advantageously between 110 and 150 N / mm 2 , and the compressive strength perpendicular to the hardwood layers is advantageously between 250 and 310 N / mm 2 .

[0022] The modulus of elasticity of the synthetic resin-compressed wood when subjected to bending load perpendicular to the hardwood layers is advantageously between 15,500 and 18,500 N / mm 2 . The modulus of elasticity perpendicular to the hardwood layers when subjected to compression load is advantageously between 2,250 and 2,850 N / mm 2 . The modulus of elasticity parallel to the hardwood layers when subjected to compression load is advantageously between 5,500 and 6,500 N / mm 2 . It has been found that synthetic resin-compressed wood with the aforementioned material properties is particularly well suited for the beam connectors according to the invention. In particular, steel connector plates can be easily replaced by the synthetic resin-compressed wood connectors according to the invention. The hole bearing strength is at least 150 N / mm 2 .

[0023] Further features and advantages of the invention will become apparent from the claims and the following description of a preferred embodiment of the invention in conjunction with the drawings. In the drawings: Fig. 1a view of a beam connection with a connector from above, Fig. 2a front view of the beam connection of the Fig. 1 , Fig. 3 a side view of the beam connection of the Fig. 1 , Fig. 4 a top view of the beam connection of the Fig. 1 , Fig. 5 a view of the connector from above, Fig. 6 several side views of wood screws for the connector set and Fig. 7 several side views of further wood screws for the connector set.

[0024] The representation of the Fig. 1shows a connection between a first beam 10 and a second beam 12, with the second beam 12 being placed on the end face of the first beam 10, resulting in a T-shaped arrangement. The beams 10, 12 are designed either as solid wood beams or as glued wood beams.

[0025] The beams 10, 12 are shown translucently so that a connector 14 arranged between the beams 10, 12 can be seen. The connector 14 would not be visible in and of itself and is therefore shown in dashed lines. Also shown in solid lines are several screws 16 that fix the connector 14 relative to the beams 10, 12. These screws are shown in solid lines, even though they are only visible on the viewer's Fig. 1 facing side in the area of ​​their respective heads.

[0026] The connector 14 has the shape of a rectangular plate and is inserted into slots 18, 20, which in the illustration of the Fig. 1 are merely indicated. A slot 18 is formed in the beam 10, starting from the upper end face thereof, and a second slot 20 is formed in the beam 12. Taken together, the two slots 18, 20 form a recess in the form of a rectangular plate, which is only slightly larger than the connector 14.

[0027] After the slots 18, 20 have been made in the beams 10, 12, the connector 14 is inserted, for example, into the slot 18 of the beam 10. The beam 12 is then placed on the beam 10 in such a way that the connector 14 is simultaneously inserted into the slot 20 of the beam 12.

[0028] In contrast to conventional beam connections, which use steel plates as connectors, the connector 14 is made of resin-coated compressed wood. The connector consists of several hardwood layers and synthetic resin arranged one above the other. The hardwood layers are bonded together using the synthetic resin and are also penetrated by the synthetic resin at least in sections. The connector 14 is therefore extremely resilient and can, above all, transfer the compressive and tensile loads between the beams 10, 12 that occur after the beams 10, 12 are installed in a timber frame structure of a building. Surprisingly, it is possible to transfer the forces occurring between the beams 10, 12 in the beam structure of a timber structure using the connector 14, which is made of resin-coated compressed wood.The load capacity of the beam connection with connector 14 is approximately the same as the load capacity of beam connections with conventional connectors made of steel plates.

[0029] After insertion into the slots 18, 20, the connector 14 is then fixed relative to the beams 10, 12 using several wood screws 16. For this purpose, the wood screws 16 are screwed perpendicular to the larger surfaces of the connector 14 through the beam 10 and the connector 14 or through the beam 12 and the connector 14. The screws 16 are thereby Fig. 1The screws are screwed through the beams 10, 12 and the connector, both on the front side facing the viewer and on the back side facing away from the viewer. The particular advantage of the connector 14 is that conventional wood screws 16 can be used. This is because the wood screws 16 can be easily screwed into the solid wood or glued wood beams 10, 12, and the screws are also designed in such a way that they penetrate the resin-coated compressed wood connector 14 without pre-drilling. As a result, the beams 10, 12 do not need to be pre-drilled after the connector 14 has been inserted.

[0030] After screwing in the screws 16, the connector 14 is fixed relative to the beams 10, 12 and the connection between the two beams 10, 12 is fully loadable.

[0031] The representation of the Fig. 2 shows a front view of the connection of the Fig. 1. Again, the beams 10, 12 are shown translucently so that the connector 14 located within the beams 10, 12 can be seen.

[0032] The connector 14 is fixed relative to the beam 12 with a total of eight wood screws 16, and the connector 14 is also fixed relative to the beam 10 with a total of eight wood screws 16. The wood screws 16 are arranged in parallel rows of four screws each. Advantageously, every second screw in each row is inserted from the opposite side. Fig. 2 Thus, in the top row of screws 16, the leftmost screw would be inserted from the front side facing the viewer. The screw to the right of it would be inserted from the back side facing away from the viewer. Such alternating insertion of the screws can then be carried out across the four rows of screws 16, whereby in the illustration of the Fig. 2The direction of insertion of the screws can also be changed from top to bottom.

[0033] The representation of the Fig. 3 shows the connection of the Fig. 1 from the side, with the beams 10, 12 again shown translucent so that the connector 14 and the screws 16 can be seen.

[0034] The representation of the Fig. 4 shows the connection of the Fig. 1 from above. Again, the beams 10, 12 are shown translucently so that the connector 14 and the screws 16 can be seen. Since a total of four screws are arranged one above the other or in the direction of view of the Fig. 4 The screws are drawn one above the other. However, each screw 16 has a point at one end and a head at the opposite end that is wider than the point.

[0035] Fig. 5shows the connector 14 from an oblique top view. It shows several hardwood layers 22, which are connected by a synthetic resin (not shown) and penetrated at least partially by the synthetic resin. After pressing and curing of the synthetic resin, the connector 14 is extremely resilient and can be used instead of a conventional steel plate connector.

[0036] Typically, the connector 14 is cut from pre-finished panel material. This can be done using conventional woodworking tools.

[0037] Figure 6shows several wood screws 26, 28, 30, and 32, of which wood screw 26 can be used in the method according to the invention. All wood screws 26, 28, 30, and 32 have a drill bit 34, which can be designed either as a drill bit with a classic drill bit geometry or as a rolled bit with scraper ribs. Each of the wood screws 26, 28, 30, and 32 is also provided with a screw head 36, with all screw heads 36 being countersunk heads. The screw 26 is designed as a so-called full-thread screw and, with the exception of the drill bit 34 and a very short cylindrical section 38 directly below the screw head 36, has a continuous wood thread 40.

[0038] In addition to the drill bit 34 and the cylindrical section 38, the wood screw 28 has two threaded sections 42 and 44 directly below the screw head 36, and a cylindrical, unthreaded section with a smooth outer surface 46 located between the two threaded sections 42 and 44. The threaded section 42 lies between the section 38 and the unthreaded section 46, and the threaded section 44 lies between the unthreaded section 46 and the drill bit 34.

[0039] For example, the wood screw 28 can be used to fasten a connector located centrally in a beam. When the wood screw 28 is fully installed, the connector is penetrated by the unthreaded section 46. This allows for a fastening of the connector that is largely equivalent to that with a dowel.

[0040] The wood screw 30 is provided with a threaded portion 48 extending from the drill tip and a thread-free portion 50 extending from the head-side end of the threaded portion 48 to the screw head 36.

[0041] The wood screw 32 is provided with two threaded sections 52, 54 and two unthreaded sections 56, 58. Starting from the screw head 36, there is first an unthreaded section 56. The unthreaded section 56 is followed by the first threaded section 52. The threaded section 52 is again followed by an unthreaded section 58. The unthreaded section 58 is then followed by a second threaded section 54, which extends to the drill tip 34. The threaded sections 52, 54 are approximately the same length, and the unthreaded sections 56, 58 are also approximately the same length.

[0042] All wood screws 26, 28, 30, and 32 have the same thread in their threaded sections. Wood screws 26 and 32 with multiple threaded sections 42, 44, 52, and 54 therefore always have the same wood thread with the same pitch.

[0043] The representation of the Figure 7 shows five further wood screws 60, 62, 64, 66, 68, of which wood screws 66 and 68 can be used in the method according to the invention.

[0044] The wood screw 60 has a disc-shaped head 70, followed by an unthreaded section 72. The unthreaded section 72 is followed by a milled section 74 with a steep thread. A threaded section 76 is then arranged from the milled section 74 to the tip of the screw. In the area of ​​the conically tapered tip of the screw 60, scraper ribs 78 are arranged opposite the wood thread.

[0045] The wood screw 72 has a hexagon head 80 followed by an unthreaded section 82. A milling section 84 with a steep thread is arranged between the unthreaded section 82 and a threaded section 86. The threaded section 86 extends to the conically tapered tip of the screw, with a counter-rotating thread 88 being arranged at the conically tapered tip in addition to the normal wood thread.

[0046] The wood screw 64 has a countersunk head 90 provided with several milled recesses 92. The countersunk head 90 is followed by a threadless section 94, which is then followed by a milled section 96 with a steep thread. The milled section 96 is followed by a threaded section 98 that extends to the conically tapered tip of the screw. At the tip of the screw, scraper ribs 78 are arranged opposite the actual thread.

[0047] The screw 66 is designed as a fully threaded screw, and a threaded portion 100 extends between the screw head 90, which is formed with the milling pockets 92. A drill bit 102 is arranged at the end of the wood screw 66 opposite the screw head 90. The drill bit 102 has a conventional drill bit geometry with two main cutting edges and two secondary cutting edges. The drill bit 102 is produced, for example, by pinching. The wood screw 68 differs from the wood screw 66 only in the design of its screw head 104. The threaded portion 100 and the drill bit 102 are identical to those of the wood screw 66. The screw head 104 is approximately cylindrical with a smooth outer circumference.

[0048] Individual characteristics of the Figure 6 and 7 The wood screws shown can be combined in any way. All of the screws shown in the Figures 6 to 7The wood screws shown are suitable for being screwed into beams without pre-drilling and for penetrating the connectors.

Claims

1. Method for connecting beams from solid wood or glued laminated wood, comprising the steps of: producing slots (18, 20) in the beams (10, 12); introducing a connector (14) from synthetic resin densified wood into the slots (18, 20); and fixing the connector (14) in the slots (18, 20), wherein the fixing of the connector (14) in the slots (18, 20) is performed by means of wood screws (16), wherein the wood screws (16) when fixing the connector (14) are screwed into the beams (10, 12) and the connector (14) without pre-drilling the beams (10, 12) and the connector (14), and wherein wood screws (16) having a full thread are used.

2. Method according to Claim 1, wherein wood screws (16) having drill tips are used.