Wooden board bending technology. Bent beams made of laminated veneer lumber: use in construction. Features of working with wood

Nature does not like straight lines and you need to spend a lot of time and effort to make wooden crafts straight. However, bending wood is also a rather labor-intensive process. Bent wood elements are often used in Scandinavian furniture in the form of beautiful, light and durable products with unity of structure and form. In this article we will look at several ways to bend wood: simple power bending, bending using cuts, steam bending and layer bending.

This is the simplest method and involves bending wood by hand and attaching it to a mold to secure the bend. The thinner the wood, the easier it is to bend. It follows from this that the greater the bend, the thinner the wood should be. Veneer can take on almost any bend, while an oak blank 2 cm thick is almost impossible to bend. It should also be taken into account that different breeds woods have varying degrees of flexibility. So the ratio of the thickness of the workpiece and the minimum bending radius for some species will be: beech - 1/2.5; oak - 1/4; birch - 1/5.7; alder - 1/8; spruce - 1/10; pine - 1/11. That is, with a beech blank thickness of 10 mm, the minimum bending radius will be 25 mm.

As a rule, the workpiece is fixed with glue, since the use of nails or screws in bending areas can lead to the formation of cracks and breaks. There is an unspoken rule - what can be fixed by hand can also be fixed with glue. When gluing, to reduce gaps, you need to move from the center to the edges, or from one edge to the other.

This method of bending wood is the least durable because the wood is sawed through almost the entire thickness and very little strength remains in it. Therefore, this method of bending wood is used only where there is no heavy load, for example rounded corners, etc.

The main material for the manufacture of bent-sawn parts is plywood. For achievement best results it is better to make cuts on circular saw using a limit stop. The cuts should be made across the grain at a distance of about 5-10 mm. from each other. The depth of the cut should be about 1/5 of the thickness of the workpiece.

To fix the bend, you can use glue or wood filler. By gluing and fixing two curved slats with cuts inward, you can create interesting elements in some designs, although with limited strength.

In terms of its physical properties, such wood is close to hydrothermal bent wood, and in some indicators dynamic loads, it has even better mechanical properties than solid wood.

The first step is to prepare the slats. The thickness of the lamellas is largely determined by the amount of bending. The greater the bend, the thinner the lamellas should be and vice versa. As a rule, the thickness of the lamellas should not exceed 3.2 mm.

The cut layers of wood are then coated with glue and pressed into the template using grippers. You cannot use regular wood glue to connect the slats. For these purposes, adhesives based on urea-formaldehyde or epoxy resins are best suited.

Before removing the part from the template, the glue should set within 24 hours. It should also be taken into account that after the mold is released, the workpiece may straighten out a little. This effect can be minimized by reducing the thickness of the lamellas or creating a shape with a slight bend.

Hydrothermal bending of wood gives the highest quality results, but requires a lot of labor and technical equipment.

Before starting the bending process, due consideration should be given to the choice of wood. Almost any type of wood can be bent, but hardwoods such as oak, beech, elm, birch, cherry, maple, walnut, and ash have the best flexibility. It is not recommended to use coniferous and soft species such as spruce, pine, cedar, and alder. It is also important that the wood is free of cracks and knots at the intended bend.

Each cell of wood fibers is coated with lignin, a glue-like chemical that binds the fibers tightly together at normal temperatures. The heat transferred by the steam softens the lignin, allowing the fibers to shrink and stretch. As the lignin cools, it hardens and binds the fibers tightly together again.

Freshly cut wood is best suited for bending. The best option is also atmospheric drying wood, since during chamber drying lignin is noticeably strengthened, making bending more difficult. Before steaming, kiln-dried wood can be soaked overnight in water. Processing of atmospheric-dried wood and pre-soaked kiln-dried wood requires the same amount of time.

Wood acquires its best plastic properties at a humidity of 25-30% and at a temperature of about 100°C. Steaming time depends on the thickness of the wood. So, for example, to steam a workpiece with an initial humidity of 30% and a thickness of 25 mm until the temperature in the center of the workpiece reaches 100°C, it takes 1 hour, and with a thickness of 35 mm - about 2 hours.

Before removing the workpiece, make sure that all tools are at hand, as the wood cools and hardens very quickly. Be sure to wear thick gloves to avoid getting burned by the steam. Remove the part and immediately secure it with the grips.

Removal of the product from the mold is usually accompanied by a slight bending. Therefore, the form must have a bend a little more than required in order to maintain the desired curvature of the product. To minimize flex, leave the piece secured in the mold for at least a few days.

If there is a need to develop a curved element made of wood, then most likely you will encounter a number of difficulties. At first glance, it will seem that it will be easier to cut out the required element in a curved form, but in this option, the wood fibers will be cut and weaken the reliability of the part. Plus, when executed, it turns out to be very large high consumption material.

Stages of work on bending boards at home:

Wood is cellulose fibers bound together by lignin. Placing the fibers in a straight line affects the flexibility of the wood material.

Tip: durable and reliable material Wood can be used to make all kinds of products only if the wood is perfectly dried. However, changing the shape of dry wood is a rather labor-intensive process, since dry wood can easily break.

Having studied the technology of bending wood, including its basic physical properties wood, allowing you to change its shape, it is quite possible to make bending wood material V artisanal conditions.

Specifics of working with wood

Bending of wood material is accompanied by its deformation, stretching of the outer layers and compression of the inner ones. It happens that the tensile force leads to rupture of the outer fibers. This can be prevented by carrying out preliminary hydrothermal finishing.

Can bend timber blanks made from laminated and solid wood. Plus, to give the desired shape, peeled and planed veneer is used. Hardwood is considered the most ductile. Which includes beech, birch, hornbeam, ash, maple, oak, linden, poplar and alder. Glued bent blanks are best made from birch veneer. It should be noted that in the total volume of such blanks, about 60% falls on birch veneer.

According to the production technology of bent wood, when the workpiece is steamed, its ability to compress increases significantly, specifically by a third, while the ability to stretch increases by only a few percent. Thanks to this, you can’t even think about bend tree thicker than 2 cm.

How bend board in artisanal conditions: heating in a steam box

First of all, you need to prepare a steam box, which can be made with my own hands. Its main task is to restrain the tree, which is required bend. There must be a hole in it that is designed for steam to escape. Otherwise, an explosion may occur under pressure.

This hole should be located in the bottom of the box. Plus, in the box you need to calculate a removable lid through which you can remove bent wood, as soon as it receives the required form. In order to hold the bent wood blank in the required shape, it is necessary to use special clamps. They can be made independently from wood or purchased at a building materials store.

Several round scraps are made from wood. Holes are drilled in them, offset from the center. After this, you need to push the bolts through them, and then drill another through the sides to push them in firmly. Such simple crafts can perfectly serve as clamps.

Now you can start steaming the wood. To do this, you need to close the wood blank in a steam box and worry about the heat source. For every 2.5 cm of product thickness, the time spent on steaming will be approximately an hour. After its expiration, the tree should be removed from the box and given the required shape by bending it. The process should be performed quickly enough, and the bending itself should be done gently and carefully.

Tip: Due to varying degrees of flexibility, some types of wood will bend more easily than others. Any method requires the application of varying amounts of force.

As soon as the result you want is achieved, the bent workpiece must be secured in this position. Fastening the tree is possible during the development of its new form, making it easier to control the process.

How bend board in artisanal conditions using chemical impregnation

Since lignin is responsible for the stability of wood, its bonds with the fibers must be broken. This is achieved chemically, and it is quite possible to do this in artisanal conditions. Best suited for such purposes ammonia. The workpiece is soaked in 25% aqueous solution ammonia, which significantly increases its plasticity. Likewise, it will be possible bend, twist it or squeeze out some relief shapes under pressure.

Advice: you should look at the fact that ammonia is dangerous! Due to this, while working with it, it is necessary to strictly adhere to all safety regulations. Soaking of wood must be carried out in a tightly closed container, which is located in a well-ventilated area.

The longer the wood is soaked in an ammonia solution, the more plastic it will become later. After soaking the workpiece and developing its new shape, it is necessary to leave it in a similar curved form. This is necessary not only to fix the shape, but also to evaporate the ammonia. However, bent wood must be left in a ventilated area. It is noteworthy that when the ammonia has evaporated, the wood fibers will acquire the same reliability as before, which will enable the workpiece to retain its own shape!

How bend board in artisanal conditions: layering method

First you need to harvest wood, which will subsequently be prone to bending. It is very, very important that the boards are slightly longer than the length required part. This can be explained by the fact that the bending tames the lamellas. Before you start cutting, you will need to draw a straight line diagonally with a pencil. This must be done across the underside of the workpiece, which will make it possible to maintain their order after moving the lamellas.

The boards must be cut with a straight edge, and not at all front side. Likewise, they can be put together with the least amount of change. A layer of cork is applied to the mold, which can help avoid any unevenness in the shape of the saw and will provide the opportunity to make a more even bend. Plus, the cork will prevent delamination in the mold. After that, glue is applied to the upper side of one of the lamellas with a roller.

It is best to use urea-formaldehyde glue, consisting of two parts. It has a high level of adhesion, but takes a long time to dry. You can also apply resin to epoxy based, but such a composition will cost a lot of money, and absolutely not everyone can afford it. The standard version of wood glue is not suitable for this type of application. Although it will dry quickly, it is considered too soft, which is not at all welcome in this option.

A bentwood product must be placed into the mold as quickly as possible. So, another one is placed on the lamella coated with glue. The process must be repeated until the bent workpiece receives required thickness. The boards are fixed together. After the glue has completely dried, it is necessary to shorten it to the required length.

How bend board in artisanal conditions: cut through

The prepared piece of wood needs to be sawn through. The cuts are calculated at 2/3 of the thickness of the workpiece. They must be located inside the bend. You need to be very careful, as rough cuts can easily deform the tree and even completely break it.

Tip: The key to cutting success is to keep the distance between cuts as even as possible. The best option 1.25 cm.

The cuts are made across the grain of the wood. Afterwards you need to compress the edges of the workpiece, which will make it possible to combine the resulting cracks into a single whole. This is the shape the bend takes upon completion of the work. After which he is corrected. In many cases, the outer side is finished with veneer, less often with laminate. This impact will give you the opportunity to correct the bend and hide almost any defects made during manufacturing. Gaps in bent wood are hidden quite easily - to do this, sawdust and glue are mixed, after which the gaps are filled with the mixture.

Regardless of the bend option, as soon as the workpiece is removed from the mold, the bend will relax a little. In view of this, it must be made a little larger in order to compensate for this effect later. The sawing method is used when bending a metal corner or part of a box.

So, using such tips you can big problems bend wood with your own hands.

Many owners of private houses are not satisfied with the traditional shape of roofs and standard sizes buildings Wood provides very wide construction possibilities, and one of them is the construction of dome-shaped structures using bent structures, which allow you to create the most original and unusual outlines of buildings using curved surfaces. In addition, curved laminated timber has many additional advantages.

Areas of application of bent wood elements in construction

This material is used not only in residential construction, but also in the construction of economic and industrial buildings.

Bent beams expand horizons in the field of design and implementation of structures, allowing you to solve the following problems:

Bent beams make it possible to bridge large distances between walls, since beams, trusses and other types of structures for roofing are made from it. This allows the construction of warehouses, buildings for keeping animals in large farms and other structures that require a large area;
Wood is resistant to various influence factors, which is why structures made of bent-laminated wood are used for the construction of warehouses;

Important! Since wood impregnated with special compounds does not rot and does not corrode at all, it becomes even more reliable than metal.

This material is used in the construction of greenhouses and greenhouses, since it can be used to create durable and stable structures of a convenient shape and large area;
The most common method of application: bent laminated veneer lumber - a material for roofs of unusual shapes and domes;

Bent laminated veneer lumber also makes it possible to build small architectural structures: with a domed roof they will be an excellent decoration for the site, they look original and unusual.

The domed roof structure is not only unusual and beautiful with aesthetic side, it is beneficial for other reasons. Snow will not accumulate on such a roof, it heats up very little from the sun and does not create a large load on the walls. It is no coincidence that this type of roofing has been used since ancient times.

Manufacturing of bent structures

How to bend a beam so that the wood does not crack, and the material itself takes on the necessary geometric shape? The production of bent beams is carried out in industrial conditions, but on the other hand, you can try to do such work with your own hands.

Bending wood is quite difficult. technological process, in which wood is exposed to several factors at once. This work requires a certain skill and strict adherence to technology, otherwise the product will turn out to be very fragile.

Typically used to make bent molds hardwoods wood, as they are more plastic and easier to process. The main species used are oak, alder, maple, ash, etc.

Coniferous species are used extremely rarely for this purpose. Most of the bent blanks for furniture and other products are made from birch veneer; this material makes up about 60% of all bent-laminated blanks. Approximate instructions for bending wood are as follows:

Fundamentals of technology for manufacturing bent elements

The basis for bending wood is hydrothermal treatment, that is, simultaneous exposure to steam and high temperature.

This treatment increases the plastic properties of wood, as a result of which it acquires increased flexibility, and its shape can be changed without causing damage to the structure of the material itself.

Wood acquires its highest plastic ability when its humidity reaches 30% and the temperature in the core of the workpiece is 100 degrees. Achieving such indicators at home is not easy, especially since steaming should be long. A beam with a cross-section of 3.5 cm must be steamed for at least 1.5 hours so that it becomes flexible.

Scheme for manufacturing bent beams

The workpiece is placed on the tire and carefully attached, after which it is steamed for the required time. The blanks are equipped with special conical or rectangular cuts that will allow the wood to bend;

The prepared material is bent until the required curvature is achieved using a tire and a press;
Still attached to the tire, the workpiece is sent to drying, where it acquires a moisture content suitable for construction work.

As a result, the workpiece acquires the required radius of curvature, and it can be used both for construction and for the manufacture of wooden elements interior design. Bent-laminated timber is made by combining two processes: the lamellas are bent and immediately glued into a single block.

Ultimately, the material retains all the positive properties, while acquiring a special shape. The technology allows you to create a wide variety of shapes with different bending radii.

If there is a need to manufacture a curved wooden element, then at first glance it may seem easier to cut out required element in a curved form, but in this case the fibers of the wood material will be cut, thus weakening the strength of the part, and as a result, the entire product. In addition, when sawing, a large waste of material is obtained, which cannot be said about the method when the wooden blank is simply bent.
Wood is cellulose fibers bound together by a chemical called lignin. The flexibility of the tree depends on the arrangement of the fibers.
Note! Only well-dried wood will be reliable and durable source material for production various products. However, the change in shape is dry wooden blank the process is complex, because dry wood can break, which is very undesirable.

Having studied the technology of how to bend wood, as well as the basic physical properties of wood, which allow you to change its shape and subsequently preserve it, it is quite possible to start bending wood at home.
Some features of working with wood
Bending of wood is accompanied by its deformation, as well as compression of the inner layers and stretching of the outer ones. It happens that tensile forces lead to rupture of the outer fibers. This can be prevented by carrying out preliminary hydrothermal treatment.
So, you can bend blanks of timber made from solid and laminated wood. In addition, planed and peeled veneer is used for bending. The most plastic are hardwoods. These include beech, ash, birch, hornbeam, maple, oak, poplar, linden and alder. Bent glued blanks are best made from birch veneer. It is worth noting that in the total volume of bent-glued blanks, birch veneer occupies approximately 60%.
When steaming the workpiece, the compressibility increases significantly, namely by a third, while the tensile ability increases by only a few percent. This means that it is not a priori worth thinking about whether it is possible to bend wood thicker than 2 cm.

Steam box heating

First you need to prepare the steam box. It can be made by yourself. Her the main task- hold the tree that needs to be bent. There should be a hole in it to allow the steam pressure to escape. Otherwise it will explode.
The steam outlet should be located in the bottom of the box. In addition, the box should have a removable lid through which you can pull out the bent wood after it has acquired the desired shape. To hold a wooden bent piece in in the required form, clamps should be used. You can make them yourself from wood or buy them at a specialty store.

Round cuttings should be made from wood - several pieces. Off-center holes are drilled in them. After this, you need to push the bolts through them, and then drill another hole through the sides to push them in tightly. Such simple crafts can become excellent clips.
Now it’s time to steam the wood; to do this, you should take care of the heat source and close the wood piece in the steam box. For every 2.5 cm of thickness of the workpiece, the product needs to be steamed for about an hour. After time has passed, the tree must be removed from the box and given the required shape. The process must be completed very quickly. The workpiece bends neatly and softly.
Note! Some types of wood bend more easily than others due to different elasticity. Different ways require the application of force of varying magnitude.
Once the desired result is achieved, the bent tree must be fixed in this position. You can secure the tree while shaping it. This makes it easier to control the process.

Using chemical impregnation

To destroy lignin bonds between fibers, you can act on wood chemicals, and it is quite possible to do this at home. Ammonia is ideal for this. The workpiece is soaked in a 25% aqueous ammonia solution. After which it becomes very obedient and elastic, which allows you to bend, twist it and squeeze out relief shapes in it under pressure.
Note! Ammonia is dangerous! Therefore, when working with it, you should follow all safety rules. Soaking the workpiece should be carried out in a tightly closed container located in a well-ventilated room.
Ammonia aqueous solutionAmmonia aqueous solution
The longer the wood is in the ammonia solution, the more plastic it becomes. After soaking the workpiece and giving it a shape, you need to leave it in this curved form. This is necessary to fix the shape, and also for the ammonia to evaporate. Again, bent wood should be left in a ventilated area. Interestingly, after the ammonia evaporates, the wood fibers will regain their former strength, and this will allow the workpiece to retain its shape!

First you need to make a piece of wood that will be bent. The boards should be slightly longer than the length of the finished part. This is because bending will shorten the slats. Before you start cutting, you should draw a diagonal line with a pencil. This needs to be done across the underside of the board. This will maintain the sequence of the slats after they have been moved.
The boards are cut with a straight-layer edge, in no case with the front side. So, they can be added together with the least change. A layer of cork is applied to the mold. This will help avoid any unevenness in the shape of the saw, allowing for a cleaner bend. In addition, the cork will keep the delamination in shape. Now glue is applied to the top side of one of the wooden slats.
The glue is applied to the lamellas with a roller. It is best to use urea-formaldehyde glue, consisting of 2 parts. He has high level grip, but takes a long time to dry. Can also be used epoxy resin, but such a composition is very expensive, and not everyone can afford it. Standard glue In this case, it cannot be used for wood. It dries quickly, but is very soft, which is not welcome in this situation.
Boards are held together after gluing. Boards are held together after gluing.
The bentwood blank should be placed into the mold as quickly as possible. So, another lamella is placed on top of the lamella coated with glue. The process is repeated until the bent workpiece acquires required thickness. The boards are fastened together. After the glue has completely dried, you should shorten it to the desired length.

I drank it as a method
The prepared piece of wood needs to be sawn through. The cuts are made 2/3 of the thickness of the workpiece. They must be with inside bending You should be extremely careful, because rough cuts can break the tree.
Note! The key to success when cutting kerfs is to keep the spacing between cuts as even as possible. Ideally 1.25 cm.
Defects can be hidden with veneerDefects can be hidden with veneer
The cuts are made across the grain of the wood. Next, you should squeeze the edges of the workpiece so as to connect the resulting gaps together. This is the shape the bend will take upon completion of the work. Then the bend is corrected. More often outside treated with veneer, in some cases laminate. This action allows you to correct the bend and hide any defects made during the manufacturing process. The gaps between the bent wood are hidden simply by mixing glue and sawdust, and then filling the gaps with this mixture.
The cuts are made across the grain of the wood. The cuts are made across the wood grain.
Regardless of the bending method, once the wood is removed from the mold, the bend will relax slightly. In view of this, it needs to be made a little more in order to subsequently compensate for this effect. The sawing method can be used when bending part of the box or metal corner.
So, using these simple recommendations You can bend a tree with your own hands without much effort.

If there is a need to manufacture a curved wooden element, then at first glance it may seem that it is easier to cut out the desired element in a curved form, but in this case, the fibers of the wood material will be cut, thus weakening the strength of the part, and as a result, the entire product . In addition, when sawing, a large waste of material is obtained, which cannot be said about the method when the wooden blank is simply bent.

Wood is cellulose fibers bound together by a chemical called lignin. The flexibility of the tree depends on the arrangement of the fibers.

Only well-dried wood will be a reliable and durable source material for the production of various products. However, changing the shape of a dry wooden blank is a difficult process, because dry wood can break, which is very undesirable.

Some features of working with wood

Bending of wood is accompanied by its deformation, as well as compression of the inner layers and stretching of the outer ones. It happens that tensile forces lead to rupture of the outer fibers. This can be prevented by carrying out preliminary hydrothermal treatment.

So, you can bend blanks of timber made from solid and laminated wood. In addition, planed and peeled veneer is used for bending. The most plastic are hardwoods. These include beech, ash, birch, hornbeam, maple, oak, poplar, linden and alder. Bent glued blanks are best made from birch veneer. It is worth noting that in the total volume of bent-glued blanks, birch veneer occupies approximately 60%.

When steaming the workpiece, the compressibility increases significantly, namely by a third, while the tensile ability increases by only a few percent. This means that it is not a priori worth thinking about whether it is possible to bend wood thicker than 2 cm.

Steam box heating

First you need to prepare the steam box. It can be made by yourself. Its main task is to hold the tree that needs to be bent. There should be a hole in it to allow the steam pressure to escape. Otherwise it will explode.

The steam outlet should be located in the bottom of the box. In addition, the box should have a removable lid through which you can pull out the bent wood after it has acquired the desired shape. To hold the bent wood piece in the desired shape, clamps should be used. You can make them yourself from wood or buy them at a specialty store.

Now it’s time to steam the wood; to do this, you should take care of the heat source and close the wood piece in the steam box. For every 2.5 cm of thickness of the workpiece, the product needs to be steamed for about an hour. After time has passed, the tree must be removed from the box and given the required shape. The process must be completed very quickly. The workpiece bends neatly and softly.

Some types of wood bend more easily than others due to different elasticity. Different methods require different amounts of force to be applied.

Once the desired result is achieved, the bent tree must be fixed in this position. You can secure the tree while shaping it. This makes it easier to control the process.

Using chemical impregnation

To destroy the lignin bonds between fibers, you can treat the wood with chemicals, and this can be done at home. Ammonia is ideal for this. The workpiece is soaked in a 25% aqueous ammonia solution. After which it becomes very obedient and elastic, which allows you to bend, twist it and squeeze out relief shapes in it under pressure.

Ammonia is dangerous! Therefore, when working with it, you should follow all safety rules. Soaking the workpiece should be carried out in a tightly closed container located in a well-ventilated room.

The longer the wood is in the ammonia solution, the more plastic it becomes. After soaking the workpiece and giving it a shape, you need to leave it in this curved form. This is necessary to fix the shape, and also for the ammonia to evaporate. Again, bent wood should be left in a ventilated area. Interestingly, after the ammonia evaporates, the wood fibers will regain their former strength, and this will allow the workpiece to retain its shape!

Delamination method

The boards are cut with a straight-layer edge, in no case with the front side. So, they can be added together with the least change. A layer of cork is applied to the mold. This will help avoid any unevenness in the shape of the saw, allowing for a cleaner bend. In addition, the cork will keep the delamination in shape. Now glue is applied to the top side of one of the wooden slats.

The glue is applied to the lamellas with a roller. It is best to use urea-formaldehyde glue, consisting of 2 parts. It has a high level of adhesion but takes a long time to dry. You can also use epoxy resin, but this composition is very expensive, and not everyone can afford it. Standard wood glue cannot be used in this case. It dries quickly, but is very soft, which is not welcome in this situation.

The bentwood blank should be placed into the mold as quickly as possible. So, another lamella is placed on top of the lamella coated with glue. The process is repeated until the bent piece reaches the desired thickness. The boards are fastened together. After the glue has completely dried, you should shorten it to the desired length.

I drank it as a method

The prepared piece of wood needs to be sawn through. The cuts are made 2/3 of the thickness of the workpiece. They should be on the inside of the bend. You should be extremely careful, because rough cuts can break the tree.

The key to success when cutting kerfs is to keep the spacing between cuts as even as possible. Ideally 1.25 cm.

The cuts are made across the grain of the wood. Next, you should squeeze the edges of the workpiece so as to connect the resulting gaps together. This is the shape the bend will take upon completion of the work. Then the bend is corrected. Most often, the outer side is treated with veneer, or in some cases with laminate. This action allows you to correct the bend and hide any defects made during the manufacturing process. The gaps between the bent wood are hidden simply by mixing glue and sawdust, and then filling the gaps with this mixture.

Regardless of the bending method, once the wood is removed from the mold, the bend will relax slightly. In view of this, it needs to be made a little more in order to subsequently compensate for this effect. The sawing method can be used when bending part of a box or metal corner.