Wood species for bent parts. Cold bending of wood

In the woodworking industry, curved parts are produced in large quantities. Curved parts are manufactured in two ways: by sawing out of boards or slabs and bending straight bars (solid-bent parts) or layers of wood with simultaneous gluing (bent glued parts).

Technological process of bending wood. The technological process of bending solid wood bars includes the following operations: material preparation for bending, hydrothermal treatment, bending and drying.

Procurement of material for bending. Blanks for bending are obtained from unedged boards by cutting them on circular saws. The following requirements are imposed on blanks for bending.

The oblique layer should not exceed 10 °. With conventional bending methods, knots are absolutely not allowed in the workpieces. In blanks with simultaneous pressing, knots are allowed within wide limits, which sharply increases the output of blanks. The blanks should be cut out taking into account the allowances for the subsequent processing of parts. When bending with simultaneous pressing, in addition to the allowance for processing, there must be an allowance for pressing the wood across the fibers and an increased allowance along the length of the workpiece. In order to increase the yield of blanks for bending, it is recommended to cut boards after preliminary marking.

At small enterprises, the method of obtaining billets for bending by splitting blocks has been preserved. The chipped workpiece does not have a cross-layer, therefore, when bent, it gives a lower percentage of scrap. However, this method is very laborious, since it is performed manually and gives 20-25% lower output of blanks from the log than when sawing it.

After cutting (or splitting) workpieces for circular section parts are processed on turning-copying or circular-rod lathes, and blanks for rectangular section details - on longitudinal milling machines. You can also bend non-planed workpieces, but in this case, the boards are cut with planing saws, which give a clean and accurate cut.

Hydrothermal treatment. Hydrothermal treatment of wood before bending is carried out in order to increase the plasticity of wood. Optimum plasticity of wood is achieved when it is heated in a wet state. This is due to the fact that when heated, some of the substances that make up the cells pass into a colloidal state.

As a result, the ability of cells and all wood to deform is increased. When drying deformed (bent) wood, colloidal substances solidify and retain the shape given to the workpiece.

Hydrothermal treatment of wood before bending is carried out by boiling in hot water or steaming. For boiling, use wooden vats or metal baths and tanks. The water in baths and vats is heated by steam.

The temperature of the water is maintained at 90-95 ° C, without bringing it to a boil. The cooking time depends on the initial moisture content, size and type of wood.

When boiling, it is difficult to obtain a uniform temperature and humidity of the entire workpiece, the outer layers are oversaturated with water. Therefore, boiling in hot water is used only in cases where steaming is technically difficult.

The most widely used in production is the steaming of wood in an atmosphere of saturated steam. Steaming allows you to heat the wood to the desired temperature (70-80 ° C), regulate the moisture content of the wood and get it always close to optimal for bending, i.e. about 25-30%.

For steaming, low-pressure saturated steam (0.02-0.05 MPa) is used, which corresponds to a temperature of 102-105 ° C. Wood steaming is carried out in hermetically sealed metal drum boilers or concrete chambers. The capacity of boilers and chambers is small, designed for laying bars in the amount of 30-40 pcs.

Boilers are located at each bending machine and are connected by a steam line to each other to form a battery. Bars are placed in boilers and chambers on gaskets in order to ensure better washing with steam.

The duration of steaming depends on the initial moisture content and temperature of the wood, the size of the blocks and the steam pressure in the boiler. The steaming time is determined according to a special diagram. For example, for workpieces with a thickness of 40 mm with an initial moisture content of 30% and a steam pressure in a steaming boiler of 0.03-0.05 MPa, the duration of steaming is 12-13 minutes, and for workpieces with a thickness of 80 mm - 65 minutes.

Plywood in the case of bending to small radii of curvature can also be subjected to hydrothermal treatment. Plywood glued with synthetic adhesives is boiled, and glued with casein or albumin glue is only steamed.

The workpieces removed from the steamer or brewing tank must be bent immediately. Cooling of the outer layers of wood, which experience the greatest stresses during bending, must not be allowed.

Bending of wood and equipment. Wood bending machines are divided into two types: cold and hot forms.

Machine tools of the first type (Fig. 4.13) are used for bending into a closed loop. The bars are bent around a removable unheated rotating template 6. Template with tire 2 fits on vertical shaft 8 , which is driven in rotary motion by an electric motor through a gearbox 7.

The free end of the bar is fixed in the carriage 4, sliding on guides 3. Block 5 is laid between the template 6 and bus 2 and is fixed with a movable stop. Then the electric motor turns on, while the shaft turns 8 with a template put on it and the bar is bent together with the tire.

In the place of the bend, a roller / is installed, tightly pressing the bar to the template. The rear end of the tire is secured with a clip to the template. The template with a bar and a tire is removed from the machine and sent to the dryer, and a new template is put on the machine, and the operation is repeated.

Rice. 4.13.

7 - pressure roller; 2 - tire; 3 - guide; 4 - bar; 5 - blank;

b - template; 7 - reducer; 8 - shaft

Rice. 4.14.

7 - hook; 2 - template; 3 - emphasis; 4 - tire; 5 - blank

Roll-forming machines with hot forms are called bending-drying machines, they can be with two- and one-sided heating. Machines with double-sided heating are a hydraulic or pneumatic press with heated profile template plates, between which bending bars are clamped. In these machines, the bars are held in a clamped state until the shape is completely fixed and the workpieces are dried.

In machines with one-sided heating (Fig. 4.14), blanks 5 are laid between the hot template 2, heated steam, and a tire 4 and are fastened with an emphasis 3. Curved blanks 5 together with tires are fixed on the template with special hooks /. The workpieces remain in the machine until the shape is fixed.

This is achieved by drying the wood to approximately 15% moisture content, which takes 90-180 minutes. To increase the productivity of the bending-drying machines, the workpieces are recommended to be dried to 20% moisture before bending, to be kept in the machine to a moisture content of 12-15%, and the final drying to the production moisture of the workpieces removed from the machine is performed in drying chambers.

Bending of plywood is carried out in templates consisting of two parts: a matrix and a punch, between which plywood is laid and folded. This uses special tools, screws, pneumatic and hydraulic presses.

Bending with simultaneous pressing consists in the fact that the wood is bent around a template provided with a notch, and in the process of bending from the outside of the workpiece it is pressed against the template through a tire by a pressing roller.

The billet is rolled. The thickness of the workpiece decreases, the layers of wood on the concave side of the workpiece take a wavy shape from the indentation of the notch of the template, the outer layers are compacted. This contributes to an increase in the compression resistance of the concave layers in the wood and the tension of the outer ones.

Bending with simultaneous pressing significantly improves the bending ability of wood, allows bending wood with large knots located on the outside of the workpiece. It is used for bending softwood and softwood.

Drying of workpieces after bending. The bent blanks are dried in drying chambers to operating humidity, and the blanks are placed in the chamber together with the templates and the tires covering them. The design of the drying chambers is similar to those used for drying sawn timber.

The dried workpieces are unloaded from the chambers and sent to the cooling compartment, where they are kept for at least 48 hours to equalize internal stresses. Only after that, the workpieces are freed from templates and tires and sent to the machining workshop.

The sequence and principles of machining bent blanks on machine tools, i.e. giving them final dimensions and a clean surface do not fundamentally differ from the processing of straight workpieces.

Manufacturing of bent glued parts. To obtain bent-glued parts, hydrothermal treatment of wood before bending and drying after bending are not required. Bent parts are made of rotary cut veneer or plywood. The technological process for producing bent-glued parts consists of preparing raw materials (veneer, plywood or thin strips), applying an adhesive solution to the surfaces to be glued, gluing the blanks with simultaneous bending in molds or in templates, and holding the parts after pressing to equalize moisture and stress.

Gluing is done either in blocks or in separate parts. Pressing is carried out in hydraulic presses with molds or templates. One of three types of heating of the pressed package is used: electrical contact, steam or high-frequency currents (HFC). The most progressive heating of HDTV. This method requires less pressing time and a more even temperature distribution over the cross section of the bag.

Adhesives based on carbamide resins of high concentration and increased curing speed are used as a binder in the manufacture of bent-glued parts. The consumption of such adhesives per 1 m 2 of the surface to be spread is 110-120 g.

If you decide to decorate a room with wood or start creating beautiful furniture in a classic style, then you will need to make curved details. Fortunately, wood is a unique substance as it allows the experienced craftsman to play with the shape a little. It is not as difficult as it sounds, but also not as easy as we would like it to be.

Earlier on the site there was already a publication on plywood bending. In this article we will understand the principles of bending a solid board and a bar, we will learn how it is done in production. And also we will give useful tips from professionals that will be useful for a home craftsman.

Why bending is better than sawing

A curved wooden part can be obtained in two ways: by bending a flat workpiece, or by cutting out the required spatial shape. The so-called "cutting" method attracts users with its simplicity. For such manufacturing of parts and structures, you do not need to use complex devices, you do not have to spend a lot of time and effort. However, in order to cut out a curved wooden product, it is necessary to use a workpiece that is obviously too large, and a lot of valuable material will be irretrievably lost as waste.

But the main issue is the performance of the parts received. When cutting a curved piece made of ordinary edged lumber, the wood fibers do not change their direction.
As a result, transverse cuts fall into the radius zone, which not only worsen the appearance, but also significantly complicate the subsequent finishing of the product, for example, its milling or fine grinding. In addition, in the rounded sections that are most vulnerable to mechanical stress, the fibers run across the section, which makes the part prone to breaking in this place.

Whereas when bending, the opposite picture is usually observed, when the wood only becomes stronger. On the edges of the curved timber or board, the "end" cuts of the fibers do not come out, therefore, subsequently such workpieces can be processed without restrictions, using all standard operations.

What happens in wood when bending

The bending technology is based on the ability of wood, while maintaining its integrity, to change its shape within certain limits as the force is applied, and then to maintain it after the mechanical action is removed. However, we all know that without preparatory measures, lumber is elastic - that is, it returns to its original state. And if the applied forces are too large, then the bar or board simply breaks.

The layers of the wood work differently when bent. Outside the radius, the material is stretched, inside it is compressed, and in the middle of the array the fibers practically do not experience significant loads and have little resistance to the forces acting on the workpiece (this inner layer is called "neutral"). Critical deformation breaks the fibers at the outer radius, while the inner radius usually forms "folds", which are a fairly common defect when bending softwood. Fibers of plastic deciduous or coniferous species can shrink by 20 percent or more, while the stretch limit is about one to one and a half percent.

That is, to determine the possibility of bending (without breaking), the more important indicator will be the limit of the relative elongation of the stretched layer. It directly depends on the thickness of the part and determines the radius that needs to be obtained. The thicker the workpiece and the smaller the radius, the greater the relative elongation along the fibers. Having data on the physical properties of popular types of wood, it is possible for each of them to formulate the maximum possible ratio of the thickness and radius of parts. In numbers it will look like this:

Bending using a steel bar

Bending without using a bus

These data suggest that softwood lumber is less adaptable to free bending than dense deciduous species. To work with sawn timber on aggressive radii, it is imperative to use combined methods of preliminary preparation of parts and mechanical protection.

The tire as an effective way to avoid the destruction of wood when bending

Since the main problem is the breaking of the fibers on the side of the outer radius, it is this surface of the workpiece that needs to be stabilized somehow. One of the most common methods is to use a patch bus. The tire is a steel strip with a thickness of half a millimeter to two millimeters, which covers a beam or board along the outer radius and bends on a template along with the wood. The elastic strip absorbs part of the energy during stretching and, at the same time, redistributes the breaking load along the length of the workpiece. Thanks to this approach, coupled with humidification and heating, the permissible bending radius is reduced significantly.

In parallel with the use of a steel bar in bending devices and machines, mechanical compaction of wood is achieved. This is done using a pressing roller, which presses on the workpiece along the outer bending radius. In addition, the template form in such a device is often endowed with 3 mm teeth (with a pitch of about 0.5 cm), oriented towards the direction of the workpiece.

The task of the toothed surface of the template is to prevent the workpiece from slipping, to prevent mutual displacement of the fibers in the wood massif, and also to create a small depressed corrugation in the concave radius of the part (the fibers are pressed into the inside of the massif, therefore, problems with folds are solved).

Pressing with a tire allows you to bend coniferous and soft deciduous wood bars and boards with a minimum percentage of rejects. Note that parts made from relatively hard rocks become about ten to twelve percent thinner when bent and pressed, and pine and spruce blanks are 20-30% thinner. But the positive aspects of this method include a significant increase in the strength characteristics of the finished product, as well as a significant decrease in the requirements for the presence of defects and defects in wood blanks.

How to improve the plasticity of wood

In a normal state, lumber has elasticity, significant spatial rigidity and resistance to compression. Wood gets these valuable properties from lignin - a natural "reticulated" polymer, which gives plants their stable shape and strength. Lignin is located in the intercellular space and in the cell walls, connecting cellulose fibers. Coniferous wood contains about 23-38 percent, deciduous trees - up to 25 percent.

In fact, lignin is a kind of glue. We can soften it and turn it into a "colloidal solution" if the lumber is heated by steaming, boiling, high-frequency current (for small parts, a household microwave is also applicable). After the lignin has melted, the workpiece is bent and fixed - while cooling down, the molten lignin solidifies and does not allow the wood to return to its original shape.

Practice shows that the optimum temperature for bending solid wood (bar, rail, board) will be 100 degrees Celsius. This temperature must be obtained not on the surface, but inside the workpiece. Therefore, in many respects, the time of temperature exposure will depend on how massive the part is. The thicker the part, the longer it will take to heat it up. For example, if you use steaming to prepare for bending a 25 mm strip (with a moisture content of about 28-32%), then on average it takes about 60 minutes. It is noteworthy that the holding time under steam for parts of similar dimensions for any rocks is approximately the same.

By the way, it is believed that it is also impossible to overheat the part, since after hardening, lignin can lose its elasticity and become too fragile.

The boiling method is not often used, since the workpiece is strongly and unevenly moistened, and such water-saturated fibers and cells can break during bending, at least with the formation of pile. After cooking, the parts have to be dried for too long afterwards. But this method shows itself well if only part of the workpiece needs to be processed for bending.

Steaming allows you to warm up the workpiece evenly, and its humidity at the exit tends to approach the optimum. The most suitable moisture content for achieving maximum plasticity of sawn timber is considered to be a range of 26-35 percent (the moment of saturation of the wood grain).

To steam wood for bending at home, use homemade cylindrical chambers made of metal / polymer pipes or rectangular wooden boxes. Heating tanks, electric kettles and other similar devices, which can provide a temperature of about 105 degrees and low pressure, act as a source of steam. This is always followed by the stage of drying the part (+ holding the fixed shape) to about fifteen percent and finishing it.

Chemical methods of plasticizing wood

It is also known that it is possible to make lumber more pliable by using different impregnation compounds. There are ready-made impregnations that make wood cells more plastic, for example, "Super-Soft 2". Some practitioners soak wood in so-called textile conditioners with similar results.

But rather primitive “recipes” containing ammonia and ethyl alcohol, glycerin, alkalis, hydrogen peroxide, dissolved alum can also be used ... Many of them work very simply - they increase the workpiece's ability to absorb water and help retain moisture in the fibers.

Thin products such as veneers are sprayed, but the chemistry impregnation of normal lumber is usually done by full immersion. It takes time for the working substances to get inside the bar or rail, usually from 3-5 hours to several days (although heating helps to reduce the wait).

Largely because of the duration of the processes, chemical plasticization is not often used, although there are other problems: the cost of chemistry, change in colors, the need to provide protection from harmful fumes, the increased tendency of such curved parts to straighten ...

Tips for bending lumber using hydrothermal conditioning

Select very carefully the quality of the workpiece for bending. It is better not to use material with cracks, knots (even alive and accrete), inclined fibers. If there are no options for this, then orient the part in the bending device (machine or template) so that the defects fall into the concave radius zone, and not into the tension zone on the outer radius. Give preference to the busbar bending method.
When selecting a blank, it is imperative to provide for a change in the size of the part after molding. For example, the thickness of a coniferous bar can be reduced by 30 percent if bending with pressing is performed.
Even if you plan on extensive finishing, don't leave too much material. The thinner the workpiece, the easier it bends without breaking.
If the volume of work is small, then it is better not to cut out the blanks, but to prick them from the chocks. In this way, it is possible to avoid cutting the fibers and, as a result, defects during bending.
For bending, it is advisable to use lumber with natural moisture. If you use dry blanks, then preference should be given to those that were not processed in the drying chamber, but dried under a canopy - in an atmospheric way.
After steaming, work on the softened wood very quickly, as the lignin begins to harden almost immediately, especially in the most vulnerable outer layers of the solid wood. Usually you need to focus on a margin of time from half an hour to 40 minutes, so there is no point in making large cameras if you simply do not have time to install all the material from which into templates.
Position the material in the steam chamber so that the surfaces facing the outer radius are easily exposed to the steam jet.
To save time, many carpenters refuse to use clamping templates. Instead, they use metal staples and wedges or bumpers on the templates.
Keep in mind that a curved bar or rail will still tend to straighten. And this straightening always occurs by a few percent. Therefore, when high accuracy is required in the manufacture of a part, it is necessary to conduct tests and, based on the results obtained, correct the shape of the template (reduce the radius).
After the part has cooled in the mold, let it stand still. Some experienced furniture makers prefer to mature for 5-7 days. The tire is usually left attached to the part for the entire time.

If there is a need to make a curved wooden element, then at first glance it may seem that it is easier to cut the necessary element in a curved form, but under such conditions the fibers of the wood material will be cut, thus weakening the strength of the part, and as a result, and everything products. In addition, when sawing, a huge waste of material is obtained, which cannot be said about the method, at a time 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 placement of the fibers.

Only well-dried wood will be a reliable and durable raw material for the production of various products. But changing the shape of a dry piece of wood is difficult because dry wood can break, which is highly undesirable.

Having studied the technology of how to bend a tree, and the fundamental physical properties of wood, which allow it to change its shape and then preserve it, it is really possible to really do the bending of wood at home.

Some features of working with wood

Bending of wood is accompanied by its deformation, and compression of the inner layers and stretching of the outer ones. It is not uncommon for tensile forces to break the outer fibers. This can be prevented by carrying out preliminary hydrothermal treatment.

So, it is possible to bend billets made of solid wood and glued wood. In addition, sliced and peeled veneer is used for bending. The most plastic are hardwoods. These include beech, ash, birch, hornbeam, maple, oak, poplar, linden and alder. It is better to make bent glued blanks from birch veneer. It should be emphasized that birch veneer accounts for approximately 60% of the total volume of bent-glued blanks.

When the preform is steamed, the compression property increases significantly, namely by a third, while the tensile property increases by only a couple of percent. And, therefore, thinking about whether it is possible to bend a tree thicker than 2 cm should not be a priori.

Heating in a steam box

First, head over to prepare the steam box. It may have been made with my own hands. Its main task is to hold the tree that needs to be bent. It must have an opening for the vapor 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 cover through which it will be possible to pull out the bent tree, after it has bought the desired shape. In order to keep the wooden bent part in the desired shape, go to use the clamps. You can make them yourself from wood or purchase them in a specialized store.

It is necessary to make round cuts from wood - a couple of pieces. Off-center holes are drilled in them. Then you need to push the bolts through them, and then drill another hole through the sides in order to push them tightly. Such simple crafts can become excellent clips.

Now is the time to steam the wood, to do this, go to take care of the heat source and close the wood blank in a steam box. For every 2.5 cm of the thickness of the workpiece, it takes about an hour to steam the product. At the end of the time, the tree must be taken out of the box and given the desired shape. The process should be very fast. The workpiece bends gently and gently.

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

When the desired result is achieved, the bent tree must be fixed in this position. It is possible to fix the tree during its formation. That is why it is easier to control the process.

Using chemical impregnation

In order to destroy the bonds of lignin between the fibers, it is possible to influence the tree with chemicals, and this can be done in full at home. Ammonia is ideal for this. The workpiece is soaked in a 25% aqueous solution of ammonia. At the end of which, it becomes very obedient and elastic, which allows you to bend, twist it and squeeze out relief forms in it under the press.

Ammonia is terrible! Proceeding from this, when working with him, it is directed to comply with all safety rules. The soaking of the workpiece is directed to 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. At the end of soaking the workpiece and shaping it, it is necessary to leave it in such a curved form. This is necessary for fixing the shape, and so that the ammonia evaporates. Again, leave the bent tree in a ventilated area. It is noteworthy that after the evaporation of ammonia, the wood fibers will receive their former strength, and this will allow the workpiece to keep its shape!

Layering method

First you need to make a piece of wood, which will be bent. The boards should be slightly longer than the length of the finished part. This is because the bend will shorten the lamellas. Before you start cutting, head to draw a diagonal line with a pencil. This must be done across the underside of the board. This will allow the lamella sequence to be maintained at the end of their movement.

Boards are cut with a straight edge, never right side. So, it will be possible to add them together with the smallest transformation. A cork layer is applied to the mold. This will help to avoid unevenness in the saw shape, which will allow for a clearer bend. In addition, the cork will keep the delamination in shape. Now glue is applied to the top side of one of the wooden lamellas.

The glue is applied to the lamellas with a roller. it is more optimal to use urea-formaldehyde glue, folding in 2 parts. It has a high level of adhesion, but dries for a long time. It is possible, in addition to this, to use epoxy resin, but such a composition costs a lot, and not everyone can solve it. In this case, ordinary wood glue cannot be used. It dries quickly, but it is very soft, which is not welcome in this environment.

Place the bent wood blank into the mold as quickly as possible. So, one more lamella is laid on the lamella smeared with glue. The process is repeated until the bent blank has purchased the desired thickness. The boards are fastened together. After the glue is completely dry, go to shorten it to the desired length.

Drank like a way

The prepared piece of wood must be sawed off. The cuts are made 2/3 of the thickness of the workpiece. They should be on the inside of the bend. be extremely careful, as rough cuts can break the tree.

The key to success when cutting cuts lies in keeping the spacing between the cuts as even as possible. Perfectly 1.25 cm.

The cuts are made across the wood pattern. Then go to squeeze the edges of the workpiece so as to connect the resulting gaps together. The bend will buy this shape at the end of the work. After that, the bend is corrected. Much more often the outside is treated with veneer, in some cases with laminate. This effect allows you to correct the bend and hide every imperfections made during production. It is elementary to hide the gaps between the bent tree - for this glue and sawdust are mixed, and at the end of this mixture the gaps are filled.

Regardless of the method of bending, once the tree is removed from the mold, the bend will easily relax. In view of this, it must be done a little more in order to compensate for this effect later. The sawing method can be applied when bending a part of a box or an iron corner.

So, using such simple tips, it is possible to bend a tree with your own hands without much effort.

Wood is recognized as one of the safest materials for human health, used in construction and in the manufacture of various furniture. Its environmental friendliness can be estimated at five points, which significantly expands the scope of use of wood products. From wood, you can get a wide variety of shapes and sizes of workpieces. Specialists help with this. These technologies include the bending and gluing of wood, which are widely used in the modern production cycle.

The whole process of woodworking takes a considerable period of time. Wood first - all of this happens in woodworking companies. In the future, boards and other materials are harvested from wood.

These blanks go to factories, where they are already used to make special building materials or various furniture. In the production process, wood blanks of different shapes and sizes may be required, and therefore such techniques for working with wood as bending and gluing are widely used.

Gluing is used to make parts of the desired size and shape. Wood splicing can be done in width, length or thickness. The pre-prepared ends of the blanks can have special grooves or spikes, which increases the strength of the parts to be joined. In the gluing process, different types of wood glue are used.

Bending wood is necessary for the production of curved parts. You can bend wood manually, subject to some of the features of this work, or on special machines.

The strength and practicality of wooden products, for the manufacture of which special machines for gluing or bending are used, can be estimated at five points. In woodworking industries, they always try to comply with the entire technology of working with wood, and therefore the manufactured goods are of high quality.

Photo of the above methods of wood processing

Splicing Gluing Bending

The main stages of gluing technology

Gluing is the main process of working with wood in any furniture industry. In order to obtain a strong and high-quality workpiece, it is necessary to strictly observe the entire technology of the process of joining individual parts. The accuracy of all work is also necessary to prevent possible subsequent deformation.

The process of joining wood and wood products consists of several stages:

Preparation of the blanks themselves.
Selection and application of adhesive.
The actual gluing itself.

Preliminary preparation of wooden blocks and other blanks consists in creating special spikes or grooves in them, which can be done using a special tool - a cutter.

Using a wood splice cutter

Milling is a fairly old branch of wood processing. The first milling machines appeared more than three centuries ago. Today, milling is an irreplaceable and versatile way of wood processing.

This woodworking machine can be matched with milling cutters of various shapes - sharpened elements with different types of blades. Various parts are made with these cutters.

In the gluing process, milling machines are necessary for:

Cuts of thorns of different shapes, with the help of which separate blanks will be glued in the future.
Creation of holes in the material. Devices of folds and grooves, which are also necessary in the process of manufacturing parts of various shapes.

Milling machines are used everywhere, they can be either manual or electric. The ease of making wood blanks for gluing using a machine can be estimated at four points. In order to get an accurate blank, you first need to gain some experience.

This video provides an overview of wood splice cutters and process connections. Shown are cutters for straight and corner jointing, as well as microthorn, zigzag and wave cutters:

Automatic line for timber blanks

Splicing lumber at any production facility allows you to create high-strength materials with new, demanded qualities and also allows you to rationally dispose of production waste.

The automatic lines for splicing include several sequentially operating machines, which allow you to end up with the material you need in length and width from short workpieces. With the help of a splicing line, glued laminated timber, which is popular today, is obtained.

The entire technological process when used in production of a line for splicing wooden blanks consists of several stages, which are provided by a set of machines included in the installation:

The cut-off press provides the required material dimensions.
The milling machine prepares the dowels and grooves in wood blanks.
The glue applicator distributes the glue according to the set parameters.
The cross-cut saw completes the gluing process.

The use of a splice line in furniture factories provides high productivity, reduces the number of jobs. , obtained with the help of automatic machines, can be estimated at five points, since the whole process is strictly controlled.

This is how an automatic length-to-length splice line works:

Types of glue

The correct selection of the type of glue predetermines the quality of joining wooden blanks. The choice of glue also depends on the type of wood to be glued and on the shape of the blanks. Most often, water-resistant glue compositions are used.

Several types of synthetic adhesives are used in the furniture industry:

Thermosetting adhesives are used for gluing spike parts without heating. These types of adhesives are based on liquid resins.
Phenol-formaldehyde adhesives are used for gluing wood-based panels, wood blanks and plywood.
Epoxy adhesives are mainly used to bond wood with other materials - metal, plastic.
In woodworking enterprises, glue based on urea resins is most often used. Also, adhesives in the form of a powder are often used, which require preliminary preparation.

The gluing of parts is carried out in a cold way and by heating them. For gluing workpieces along the edges, an adhesive film is often used; it consists of sheets of various sizes.

Before gluing the parts, you must first prepare, that is, degrease, remove dirt and various types of stains. After applying glue over the entire surface and connecting the necessary blanks, the parts are clamped using special devices that remove only complete drying.

Machine tools

For splicing the glued wood, special machines in the form of presses can be used. They clamp the parts for the required time. This ensures a strong connection between the adhesive surfaces and eliminates the displacement of parts. The press can be selected according to the length of the bar, power, availability of additional functions.

Wood gluing at home

Gluing wood can sometimes be required at home. This often happens when gluing wooden furniture sets or various breakdowns. Before gluing, the surfaces of wooden products must be properly prepared.

To do this, their pores are cleaned of old glue, a layer of paint, degreased with a solvent, and dried. After applying glue to both parts, they are carefully connected and clamped in a clamp for at least 30 minutes.

Commonly used adhesives include:

Casein glue.
Synthetic wood glue provides waterproof seams.
Strong adhesion is obtained by using glue "Dubok", "Ago", "Mekol", "Mars".

In order to achieve high strength of the glued parts, it is necessary to strictly follow the instructions attached to each type of glue.

You can clearly see how wood is glued in the video:

Bending technology

Bending wood can be defined as the process of bending laminated or solid wood blanks to give them the required curvilinear shape. The bending technology is based on the plastic qualities of different types of wood. Curved wooden parts can also be obtained by processing on special machines, but this method is rarely used, since it is endowed with a number of negative consequences.

Process description

Hardwoods such as oak, beech, ash are more plastic. Therefore, for the manufacture of curved parts, the species of these trees are mainly used. Distinguish between cold and hot bending of wood.

Hot bending is based on a sharp increase in the plasticity of wooden blanks when they are heated from 80 to 120 degrees. This mode of heating is achieved by boiling in water or steaming.

The wooden blanks plasticized in this way are bent according to the prepared template and fixed with clamps, after which they are cooled and dried. When bending, the convex side is stretched to the required level, and the concave side is compressed. Thick workpieces are bent using special machines.

Cold bending is used to obtain multi-layer curved bent parts. To obtain a part of the desired shape, you need to lay several blanks greased with glue on top of each other, give them the required shape and with the help of a press machine withstand the required time. The shape of the workpieces obtained by the cold bending method lasts longer.

How curved wood is made, the video will tell:

Bending wood at home

Bending wood at home begins with the choice of material. The prepared parts must be straight-layered, they must first be dried in natural conditions. You also need to soak parts if they are made of ash, oak, beech. Before bending, the workpieces must be steamed.

To do this, you can use a steam chamber prepared by yourself. For the manufacture of such a device, a pipe and a boiling kettle are suitable, from which steam will continuously flow into this chamber through hoses.

The holding time of the blanks can only be determined empirically, but it is believed that in order to achieve the desired plasticity, it is necessary that one centimeter of wood in thickness is steamed for 30 to 40 minutes. Overexposing the product is also not worth it.

Before you start bending, you need to prepare the shape and clamps. After heating the wood, it is well exposed to bending for only 5-10 minutes, so everything needs to be done extremely quickly. The products are kept in shape until they are completely dry, usually it takes at least one week. The finished part can then be machined or posted.

They use such a wood processing process to make different types of furniture with their own hands. At the same time, the price of products is significantly reduced and this can be estimated by five points. But the laboriousness of the whole process takes a lot of time and therefore only truly enthusiastic people can take up bending wooden blanks and their subsequent use.

Examples of interior elements made of bent wood

Headboard Rocking chair Table Decorative element Chairs