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Despite all its strength and durability, wooden parts can be easily and simply bent if suddenly during the construction process you need some special, and original oval or round shape. When properly processed, wood can easily be changed in shape, and this procedure you can use your own on our own without resorting to the help of professionals.

Types of work

There are two main ways to bend wood to the desired shape, one of them is cold, the other is hot. As the name implies, the methods differ only in the use of hot temperatures; in terms of effectiveness, both of these methods are exactly the same, just hot way fixing the tree is much faster. For each method you will need glue, pva or wallpaper, depending on what you have at hand, you don’t need to buy anything special. And with the help metal parts you can create a kind of press or frame that will hold the tree in the desired shape. In order to bend the beam, you need to lubricate it with glue, firmly and thoroughly, without fear that the wood will become wet. In fact, under the influence of the adhesive solution, all excess moisture will leave the wood, and it will become even more durable and strong, which is extremely important. After the timber has been lubricated with glue, it must be secured using tools in the desired shape, and in the case of a cold work process, simply left fixed to dry. If you choose a hot one, then cover the timber with regular film so that it dries faster and all the moisture evaporates.

Durability

Whichever method is chosen, they are both effective and work the same way. The beam is completely fixed in its new form and will no longer return to the old one. You can bend a wet beam with glue as much as possible without fear that it will break. And as a result, you will receive an original and beautiful piece of furniture or detail to create an even more attractive interior of the house or its facade. The beam bent with glue will not even need to be treated with anything for durability, which is extremely convenient. Moisture will not penetrate through glue solution, and insects will not encroach on a tree that contains much more glue. That is why this method is the most optimal and practical if you urgently need to bend a wooden beam.

Often during the process repair work There is a need to obtain curved surfaces of products made from wood. How to bend a board so that the bend is strong and does not crack during the bending process? Well, if you have already decided to do major renovation with your own hands, then you should not retreat in the face of such difficulties. In this article we will talk in detail about how to give wood material a curved shape.

No, our task is not at all to bend an innocent plant. We are talking about wood building materials. How to bend a tree so that it bends and does not break? Bending method wooden products known since ancient times: to give wood a shape, only heat and moisture are needed, under the influence of which the plasticity of the material increases with all the ensuing consequences. How to bend a tree? Hold it in hot water(the higher the temperature, the faster the processes occur) or treat with steam (a steam generator can be made from a kettle or use an iron). The higher the temperature, the faster the wood gives way and you can start bending it. Moistened and heated wood can be bent under the influence of a load (the ends of the board are placed on supports), and a load is placed in the place of the future bend. Dried wood perfectly retains the minimum radius of curvature that was achieved during the bending process. Now we know how to bend wood, we can dwell on this issue in more detail.

Wood reaction to external influences

The fact is that wood reacts differently to bending. The convex part is subject to tension, the concave part is subject to compression. Moreover, the material also reacts differently to steaming. For example, the ability to compress increases by as much as a third, but the ability to stretch - just a couple of percent. That’s why you shouldn’t think about how to bend a board more than two centimeters thick at home. It is also necessary to take into account that different types wood reacts differently to bending. For example, such species as oak, larch, and maple bend poorly, but beech, ash, and walnut bend well. So before you think about how to bend the board, decide on the type of wood from which it is made.

How to bend plywood, fiberboard, MDF

At home, plywood is bent by increasing its humidity, then ironing it (an iron is required), and fixing it in a template. Any template can be used frame element and it is not at all necessary that its shape should be curvilinear. The product is attached to the template using tape. You can clamp bent plywood between two spacers, give it a bent shape using ropes, tying them around the product in several places along the radius of curvature. Plywood can only be used after it has dried. It seems that we have figured out how to bend plywood - let's move on.

How to bend fiberboard? The technique is the same as in the previous case! How to bend MDF? In this case, you can go two ways: either bend thin sheets (no more than 5 mm) and glue them together, or use flexible MDF, in which there are transverse slots on one side. The thickness of such sheets is usually 8 mm. When bending, they are placed on top of each other with their milled sides, and then glued together. That's all!

The layers are carefully lubricated with glue, placed in a template and pressed into place. Bent glued units made from veneer, from hardwood and softwood boards, from plywood. In bent-laminated veneer elements, the direction of the fibers in the veneer layers can be either mutually perpendicular or identical.

When manufacturing bent-profile units with longitudinal cuts, it is necessary to take into account the dependence of the thickness of the bent elements on the type of wood and the thickness of the bent part.

As the bending radius of the slab increases, the distance between the cuts decreases, as can be seen in the figure above. That is, the width of the cut directly depends on the bending radius of the slab and the number of cuts.

Now let's consider theoretical aspects bending

Curved parts from solid wood can be produced in two basic ways:

cutting out curved workpieces and giving a straight bar a curved shape by bending it on a template. Both methods are used in practice and have their advantages and disadvantages.

Sawing curved blanks is characterized by simplicity of technology and does not require special equipment. However, when sawing, the wood fibers are inevitably cut, and this weakens the strength so much that parts with large curvature and a closed contour have to be made up of several elements by gluing. On curved surfaces half-end and end surfaces of cuts are obtained and, in connection with this, the processing conditions on milling machines and finishing. In addition, when cutting it turns out a large number of a large amount of waste. The production of curved parts using the bending method requires, compared to sawing, a more complex process. technological process and equipment. However, when bending, the strength of the parts is completely preserved and even in some cases increases; end surfaces are not created on their faces, and modes post-processing for bent parts do not differ from the processing modes for straight parts.

Element bending
A- nature of the workpiece deformation during bending;
6 - bending the workpiece with the tire according to the template:
1 - template; 2 - notches; 3 - pressing roller; 4 - tire

When bending the workpiece within elastic deformations normal to cross section stresses: tensile on the convex side and compressive on the concave side. Between the zones of tension and compression there is a neutral layer, the normal stresses in which are small. Since the magnitude of normal stresses changes along the cross-section, shear stresses arise, tending to move some layers of the part relative to others. Since this shift is impossible, bending is accompanied by stretching of the material on the convex side of the part and compression on the concave side.

The magnitude of the resulting tensile and compressive deformations depends on the thickness of the bar and the bending radius. Let us assume that a block of rectangular cross-section is bent along a circular arc and that the deformations in the block are directly proportional to the stresses, and the neutral layer is located in the middle of the block.

Let us denote the thickness of the bar H, its initial length through Lo, bend radius along the neutral line through R(Fig. 60, a). The length of the block along the neutral line when bending will remain unchanged and is equal to Lo = p R ( j /180) , (84) where p is the number pi(3, 14...), j - bend angle in degrees.
The outer stretched layer will receive elongation D L (delta L). The total length of the stretched part of the bar is determined from the expression Lo+ D L= p (R + H/2) j /180 (85)
Subtracting the previous one from this equation, we obtain the absolute elongation
D L= p (H/2)( j /180). (86)
Relative extension Er will be equal to D L/Lo = H/2R, i.e. bending elongation D Ll/Lo depends on the ratio of the thickness of the bar to the bending radius; the thicker the block, the larger it is H and the smaller the bend radius R. A similar relationship for the value of relative compression during bending can be obtained in a similar way.
Let's assume that around the pattern R" bent block with initial length Lo and at the same time maximum compressive and tensile deformations are achieved. Designated by E szh the value of permissible compressive deformation of wood along the fibers, and through E grow the value of the permissible tensile strain along the fibers, we can write a relationship for the stretched side
L = Lo(1 + Erast)= p (R" + H) j /180 (87)
From here R" + H = / p ( j /180) .
For the compressed (concave) side there will be L 2 = Lo (1 - Eczh) = p R"(j/180)
or R" = / p ( j /180 ). (88)
Subtracting the second from the first expression, we get
H = )