How to learn to saw on a band sawmill. Sawing frozen wood on a band saw

The economic efficiency of sawmill production largely depends on the degree of use of raw materials. The equipment used in production, rational cutting of logs according to optimal deliveries, competent planning of cutting determine the efficient use of resources and, accordingly, high product quality.

The main schemes for cutting sawn raw materials

Methods and schemes for cutting logs directly depend on the requirements for the quality and size of products, the characteristics of raw materials and the type of equipment used.

The main methods of sawing logs
a - waddle; b - with a bar; b '- with the receipt of two bars; b "- waddle bars; in - sector; in '- sawing the sector into radial boards; in "- on tangential boards; g - segment; g '- breakup-segment; g "- beam-segment; d - circular; 1 - unedged boards; 2 - edged boards; 3 - rail; 4- bars; 5 - parts of logs in the form of sectors; 6 - parts of logs in the form of segments; 7 - one-sided edged boards

cutting logs waddle consists in its division along parallel planes by one or more cutting tools. This scheme allows you to get unedged boards with different arrangement of layers relative to annual layers. The method is rational when cutting logs up to 18 cm in diameter and for sawlogs with trunk curvature (most often used in cases of cutting birch raw materials, which have simple or complex curvature in 70% of cases).

Unedged boards obtained after cutting at random are processed into edged boards or transferred for cutting into blanks in unedged form.

In the event that the majority finished products must have established cross-sectional dimensions, the cutting method is applied with bar. This scheme is also used for cutting logs of large diameters in the production of general purpose lumber.

Sawing with a bar is carried out on multi-saw equipment in two passes. At the same time, at the first stage, bars are obtained from roundwood with a thickness equal to the width of the required board. Then these bars are divided into boards of the required dimensions in thickness.

For cutting large-sized ridges, they are used segment and sector methods. It should be noted that these schemes are specific and are used in special types of production for the production of tangential and radial lumber.

Individual cutting of large logs and logs with internal rot is carried out in a circular way.

Processing of round wood by milling

The formation of the section of sawn raw materials by milling is carried out by combining this method with sawing. In this case, three main cutting schemes are used:

obtaining a double-edged beam at the first node;
obtaining unedged boards and two-edged timber on the head machine;
obtaining a profiled beam with dimensions corresponding to the cross-sectional dimensions of edged lumber with the development of boards on one equipment.

Double-edged timber is a semi-finished product for the further production of edged lumber by dividing the timber into boards.

The main methods of cutting logs by milling
a - obtaining a two-edged beam on the head machine; b - obtaining a two-edged beam and unedged boards; c - obtaining a profile bar; g - obtaining long edged lumber; e - obtaining edged lumber various lengths; e - obtaining edged lumber of various lengths and widths; 1 - lumber zone; 2 - edged lumber; 3 - curly timber; 4 - two-edged timber; 5- unedged lumber

The concept of setting for sawing round wood

A set is a set of saws, clamping and inter-saw spacers installed in a saw frame to obtain sawn materials with specified thickness parameters.

In other words, a delivery is a plan-scheme for sawing sawmill raw materials (logs) of uniform quality and size into products of specified parameters and quality.

When sawing in a waddle, the setting is implemented by a digital series showing the thickness of the sawn boards in millimeters:

19-19-32-32-19-19.

This row of numbers means that two boards 32 mm thick are cut from the central part of the log, and four boards 19 mm thick are cut from the side parts.

When breaking up with a bar, for example, the setting is written in two rows of numbers, for sawing a log (first pass) and a beam (second pass):

19-19-150-19-19 (first pass);

19-32-40-40-32-19 (second pass).

As in the previous example, these numbers mean that on the head machine of the first row, on which the log is sawn, one beam with a thickness of 150 mm is obtained and, accordingly, four unedged boards of 19 mm each (two on each side), and on the machine of the second rows, the resulting timber is sawn into boards with a thickness of 40, 32 and 19 mm.

When sawing logs on single-saw machines, the setting determines the order of cutting.

Drawing up deliveries

Drawing up a set essentially means defining optimal sizes and the proportions of the boards in terms of thickness, ensuring the rational use of the cross section of the diameter of the log.

Basic rules for compiling a delivery:

postavy should be symmetrical;
in one set there should not be boards that differ in thickness by less than 5 mm;
start drawing up the set with the largest lumber in terms of cross-section;
the dimensions of the thicknesses of the boards should decrease from the axis of the log to the periphery;
do not provide for sawing out more than two thin (16, 19 mm) boards at the edge of the set when cutting raw materials on sawmill frames;
choose the height of the timber on the first pass according to the width of the leading boards in the specification according to the dimensions of the thicknesses of the boards;
the face of the timber, sawn in the second pass, sawn into boards of equal thickness;
when compiling deliveries for lumber without specifying specifications, use tabular or graphical methods;
when sawing using the method with a bar, determine the thickness of the bar from the ratio (0.06-0.08) of the top diameter of the log - d;
the setting should not exceed the value of the maximum coverage of the diameter of the log;
determine the smallest thicknesses of the central boards according to this table:

Graphical method of drawing up assignments

It is possible to draw up a rational delivery in accordance with GOSTs without specifying specific cross-sectional dimensions (without tasks in the form of specifications) - using special graphs.

An example of using the graph of the limiting thicknesses of lumber according to P.P. Aksenov

In order to determine the limiting thicknesses on the abscissa axis, the distance from the axis of the set to the inner part of the face of the set of the required board is plotted. Then a vertical line is drawn until it intersects with an inclined line that corresponds to a given diameter, and the resulting intersection point is taken down to the coordinate axis.

Graph of optimal lumber thickness according to G.G. Titkov

tree, along with natural stone, is one of the oldest building materials. Despite the huge variety of various artificially created materials currently present on the construction market, wood is still in constant demand. Wood is versatile and available material, and not a single construction event can do without its use.

The main raw material for the production of lumber (beams of various sections, edged and unedged boards, etc.) is a log - freed from branches and twigs, as well as from the thinnest upper part of the tree trunk. Logs can be used as a completely independent building material as poles, piles, masts, etc., but in most cases they are subject to sawing to obtain beams and boards. How to saw a log into boards, beams and other lumber, and will be discussed further.

Sawing a log can be carried out in various ways:

manually, using a saw tool;
at sawmills;
on woodworking machines and specialized lines.

The price of lumber largely depends on its thickness and the amount of production waste.

In order to make the most rational use of the available raw materials and correctly saw the log, the woodworking industry uses special sawing schemes to reduce the percentage of waste and thus reduce the cost of the final product. Therefore, before sawing a log yourself, it would be useful to familiarize yourself with such schemes.

Tools and equipment for sawing logs

Depending on the total number of logs, their length, thickness and the expected quality of the future lumber, various tools and specialized equipment are used for sawing. To obtain a small amount of lumber at home, a manual method of processing trunks using chainsaws and conventional hand saws with teeth for longitudinal sawing is quite acceptable.

A sawmill is a fairly common type of sawmill equipment. It is a woodworking machine with frame saws, designed for longitudinal cutting of logs to obtain edged boards and timber. On sawmills it is possible to process logs with a diameter of 15 to 80 cm and a length of up to 7 m.

Sawing tree trunks on circular (circular) machines is carried out by means of a circular saw. Such machines can be single-saw (single-disk) and multi-saw (multi-disk). Single-disk circular saws work, as a rule, with small-sized and low-quality starting material. Multi-disc machines are designed for cutting round timber of large diameter.

The most popular at present are the so-called band sawmills, both vertical and horizontal. As a cutting tool, they use a tape fabric worn on pulleys. Belt machines provide high-quality longitudinal and mixed sawing of logs into boards and beams with a minimum amount of waste.

Lines for sawing wood are used in large enterprises in the production of lumber on an industrial scale. They provide high surface quality and precise geometry of the final product and have the highest productivity.

In addition to the above, in the mass production of lumber, other types of highly specialized sawmill equipment are also used: debarking, edge trimming, band-cutting and other machines.

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Types and methods of cutting logs

Before sawing a log into boards and beams, it is important to choose the most optimal sawing method, which is determined by the size, geometry and surface quality of the future lumber, the necessary technical requirements, and the type of wood. According to the orientation to the growth rings of the trunk, it is possible to distinguish the types of sawing. This:

radial, carried out clearly along the radius of annual rings;
tangential, when sawing is done tangentially to annual rings, parallel to one of the radii;
parallel-forming, when cutting occurs parallel to the direction of the fibers (thus, the minimum fiber inclination in the lumber is achieved).

Depending on the direction of sawing, there are several ways to saw logs:

sawing waddle;
sawing with a bar;
segment method;
sector method;
circular cutting.

Sawing waddle is carried out using several parallel cuts along the entire plane of the section of the log and gives no output. edged board and two croakers. Sawing waddle is the most in a simple way log processing and is used primarily for cutting small-diameter hardwood rounds, since other methods greatly reduce the width of the finished lumber.

Sawing with a bar means cutting out at first initial stage double-edged timber and side boards. The beam is subsequently sawn into edged boards of the same width. Up to 60% of all raw materials are cut with a bar. The disadvantage of this method is the need for the simultaneous use of two sawmills.

The above methods are the main ones. Special methods are used much less often: sector and segment. With sector sawing, the log is first divided into several fragments - sectors, from 4 to 8 in number, depending on the diameter of the trunk. Then these sectors are sawn into boards in radial or tangential directions.

With the segment method, a beam is cut from the central part of the log, as a result of which two so-called segments remain on the sides. The resulting segments are then cut into tangential boards.

The circular sawing method is used for individual cutting of logs and allows you to separate healthy wood from the affected one. In circular sawing, after sawing off the next board or several parallel boards, the trunk rotates around the longitudinal axis by 90 ° each time.

For a small woodworking industry specializing in sawing wood into boards and beams, the optimal equipment to use is. It has good productivity, allows you to dissolve large-sized trunks into lumber. But in order for the equipment to work with full efficiency during the work, you need to know how to cut on band sawmill. Taking into account certain recommendations and features of the operation of such a unit will allow you to avoid problems and get high-quality business material at the output.

The process of sawing timber with this sawmill comes down to the fact that the log is placed and fixed on a special frame, which also acts as a guide. A frame with a cutting tool mounted on it, driven by an electric motor or internal combustion engine, moves along the barrel along the rails.

Preparatory stage

One of the main conditions for the normal operation of the equipment is the preparatory work before sawing on a band sawmill. And they include:

cleaning the sawn log from dirt and sand;
evaluation of the tree (breed, humidity);
selection of a saw (shape, profile, sharpening angles of teeth) depending on the material being cut;
correct performance of adjustment work (tensioning of the cutting element, drive belts).

Proper preparatory work will allow you to quickly saw the wood with proper quality.

An important factor for normal sawing is the correct sharpening and setting of the saw. These works should be carried out only on special machines. A well-sharpened saw with a properly selected tooth profile will provide high speed work and a clean cut.

Attention should be paid to the adjustment of the cutting blade. Correctly tensioned tape will ensure an even cut. Any violation of the tension will lead to a "waviness" of the surface of the boards, or to a rush of the cutting tool.

The more sand and dirt on the wood, the faster the saw will become dull, which will greatly affect the performance of the equipment. Therefore, it is better to prepare the material before sawing, as well as to sharpen and set the cutting tool in a timely manner.

sawing process

In the process of sawing, it is important to ensure a uniform speed of movement of the bed along the log. This will eliminate the possibility of idle tape movement and ensure maximum productivity.

Before sawing wood with a high resin content on a band sawmill, care should be taken to ensure that water or cleaning solution is supplied to the cutting area. This will prevent sticking of the teeth and ensure a good cutting speed.

After each pass, you should evaluate the quality of the cut and make sure that there is no “waviness”, and only then continue to cut the log. This will allow you to immediately identify problems with the configuration of the equipment and eliminate them in a timely manner.

Periodically, it is necessary to clean the moving elements of the sawmill from sawdust. This will eliminate unnecessary vibrations during the operation of the unit, which may affect the quality of sawing, and will also extend the life of the units.

In general, sawing on a band sawmill is not difficult, the main thing is to fully adhere to the manufacturer's recommendations regarding operation. should not be neglected and preparatory work, because the performance of the unit directly depends on them.

Boards and timber are one of the main building materials. But not everyone has the financial means to buy finished boards. In such situations, one of the ways out is to independently harvest wood on a plot taken from the forestry.

The advantage of a chainsaw as a tool for sawing logs

You can cut a log using a sawmill, a gas or electric saw and additional devices. When choosing one of these tools, the scope of the work ahead should be taken into account. The cost of the cheapest stationary sawmill, together with all components, is 150 thousand rubles. A chainsaw is much cheaper. It is more convenient than an electric saw for the following reasons:

It does not require electricity to operate the tool - this makes it possible to use the chainsaw on the plots.
It is more powerful than the electric saw.
Starts smoothly and allows you to conveniently adjust the speed, which reduces the likelihood of chain breaks.
The operation of the inertial brake is faster than that of an electric saw.
Long working time without interruption - up to one hour.
Can be used in high humidity conditions.

Types of working nozzles

When sawing logs with a chainsaw, various nozzles are used.

Nozzle for longitudinal cutting. It is used for sawing logs along, the process takes place in a horizontal position. After work, the master receives the same thickness of the product. Finished materials are subjected to a drying process, after which the boards are used in construction. By appearance the device is a frame small sizes, it is attached to the tire on each side.

Drum debarker (rounder). With the help of such a nozzle it is easy to dissolve the log, it works due to the V-belt transmission. It is attached to the belts on both sides, for this purpose special pulleys are used. The speed of rotation of the shaft depends on the size of the pulleys, so the performance of the nozzle is easy to change. This technology forces the master to carefully monitor each stage of the process, some specialists use an assistant during this cut. But this option requires increased security measures.
Sawing with a lightweight nozzle. Method is no different high performance but is used quite often. The element is fastened on one side, but the workpieces are slightly uneven. Such materials are necessary for the construction of sheds or fences.

Features of sawing with a homemade tool

You can easily cut a log into boards with the help of a self-made tool. It's easy to make. To do this, follow these steps:

As a support, you need to use a frame from a school desk or a pipe with a section in the form of a square, its optimal size is 20x20, and more is allowed.
It is necessary to build two clamps, mount a cross member with two holes for the tie bolts at one end, and make a protrusion for the tire in the middle.
For longitudinal sawing of a log into boards, you need to make a support frame, its width should be seven to eight centimeters less than the length.
Then two parts ten centimeters long are welded to both sides, holes are made for the bolts, a handle is attached in the middle for ease of operation.
Then you need to insert the clamps into the grooves, install the tire, carefully fix everything.

It is not difficult to work with a home-made tool, this will require goats, they will serve as a support. In addition, you need to prepare a metal rail or board to use it as a guide. A log is laid from below, the required height for work is set.

The procedure for performing preparatory work

To cut a log lengthwise, you need to perform the following sequence of actions:

Take two straight boards and attach one to the other at a right angle. The result is a strong leading ruler.
To maintain the manufactured ruler, you need to make stops from the boards.
The movement of the trunks must be performed using a tilter.
The log should be placed on a comfortable base.
On the chainsaw tire using nuts, you need to fix the frame.
The supports of the leading ruler must be attached to the ends of the log, checking the horizontal position with a level.
Self-tapping screws must be used to fix all brackets and structural elements. Nails are not suitable for these purposes, since it is difficult to remove them in the future without causing damage to structural details.
The leading ruler must be attached to the supports with brackets and its height adjusted, taking into account that the cut will not go along it, but approximately one centimeter higher.
The log must be rotated and the second board must be fixed in such a way that it rests on the ground and supports the log.

The procedure for performing basic work

Now you need to start the chainsaw and make the first cut.
Next, you need to free the log from the stops and boards and attach the leading ruler on the cut surface of the log in the direction of the next cut. The ruler is fastened directly to the surface or to the ends of the log using supports. The second cut is made perpendicular to the first cut.
The log must be turned and fixed with a board point-blank to the ground.
A guide ruler is not required to perform the following steps. One of the cut sides serves as a guide.
It is necessary to adjust the thickness of the cut on the frame and saw off the log from the other side in such a way that you get a bar with bark remaining on only one side.
This beam must be turned over and fixed in such a way that the fixing point of the fixing board is as low as possible.
Then it is necessary to adjust the frame to the required thickness of the board and saw the timber into boards.

Safety rules when performing work

Do not use the saw blade without the guard.
Wear earmuffs, gloves, goggles, heavy clothing and a respirator.
Do not pour fuel into the hot tank of the tool, you need to wait until it cools down.
Children must not be allowed in the work area.
It is necessary to start the tool on the ground with the chain brake applied, which must be released just before starting to cut.
You should always have a first aid kit on hand.
When working, you need to hold the chainsaw by the handle of the arc, moving it forward along the guide. Do not press hard on the chainsaw - it should move freely.
Right-handers should place the log on their right side, left-handers on their left.

The specification of sawmill raw materials is given in the task for the course project.

According to the specification, edged lumber is required, a significant part of which is a certain width. Therefore, the lumber method of cutting logs is chosen. In addition, logs with a diameter of 34, 32, 30, 28, and 26 cm are intended for cutting, which can be sawn using this method. In the specification of lumber, the most difficult (basic) assortment is boards with a thickness of 50 mm and a width of 275 mm. When producing lumber of a certain section in accordance with the rules for compiling sets when sawing with a bar, the thickness of the bar of the maximum volume is 0.6-0.8 of the top diameter of the log. Therefore, for the production of lumber with a width of 275 mm, sawn raw materials with a diameter of 34 cm are selected. Simultaneously with the main assortment, sawing out of lumber with a thickness of 25 and 19 mm is provided.

In table. 8.1 shows setting No. 1 for a board with a section of 50275 mm, boards with a thickness of 25 and 19 mm from logs with a diameter of 34 cm.

Let's determine the volumes of boards of the main and passing assortment from logs with a diameter of 34 cm with a volume of 94.16 m 3:

The obtained values are recorded in the corresponding columns of the “Plan for cutting logs into lumber”.

Total lumber for delivery (m 3). The correctness of filling out the “Plan for cutting logs into sawn timber” is determined by comparing the calculated volumetric yield with the actual yield according to the delivery P = 65.41%.

In this example, the task for the production of sawn timber of the main assortment was overfulfilled. The remaining volume of logs can be sawn into the following lumber according to the specification.

The resulting value is recorded in the plan for cutting logs, because the raw material of this diameter remains, we use it to obtain the next main assortment of 50 × 200 mm. and the calculations are repeated.

Similarly, we make calculations for subsequent sections, the results of the calculation are recorded in Table. 8.1.

Sawing wood is a cycle of actions using a variety of technologies aimed at obtaining lumber from round timber suitable for further use in industry. The duration and labor intensity of the process depend on the chosen method of processing round timber, as well as the time of year.

Tool and equipment

Trunks and large-sized branches go into production. All material is divided into groups according to the thickness and presence of bark. Often, wood processing enterprises have workshops near the harvesting site, in which machines are installed for the initial processing of wood.

Manual debarking of the forest

The wood that has not passed the debarking stage can be used on the construction of floors or as a ridge beam in the corresponding interior, or as a supporting device during construction.

Industrial debarking

If another option for using the tree is planned, then sawing is carried out, resulting in the following segments:

unedged and semi-edged (rough material from which the bases of the floor, walls or ceiling are mounted);
edged (designed for finishing flooring).

The sawing can be carried out by a field organization that has all essential tool.

Tree sawing map

The rational use of the material is ensured by compliance with the sawing map. This allows you to reduce the cost due to waste, the percentage of which the card can significantly reduce. The used tools and types of forest processing equipment depend on the volume, desired quality and size of the finished lumber.

Wood sawing machine

Most often use a circular saw and various machines:

the circular saw allows you to make precise cuts of various directions. Suitable for both professional and home use, perfectly copes with the diameter of the round timber above the average;
chainsaw;
machines for clean removal of bark;
sawing on a band sawmill makes it possible to process dense logs, it is considered the most popular, since the output is high-quality material and a small amount of waste;
disk machine: production of two-edged timber and unedged boards;
a frame sawmill does not need a foundation, the technology with its use allows you to install equipment in close proximity to the cutting site;
the thinner is processed by universal machines, the output gives high-quality building materials even from low-grade whips;
sawing round timber at a large woodworking enterprise should be carried out with the largest amount of sawn timber, which differs from the rest in special quality and exact dimensions. For this purpose, special lines are installed for sawing.

At the sawmill, a beam and an edged board are obtained due to the cut of a log up to 7 m long and 15-80 cm in diameter along the longitudinal line. The circular saw has one or more discs, it processes different diameters of the forest according to their number.

If at home it is necessary to process a small amount of wood, then you can use a regular chainsaw.

cutting wood

Before choosing a tool, you need to decide on the type of cut, focusing on the annual rings of the log. There are several types:

radial (along the radius);
tangential (the cut is parallel to one radius, touches the annual rings);
the fibers are arranged parallel to the cut being made.

Among the cutting methods, the one that is most suitable for a particular case is selected:

Razval. Sawing wood in this way is carried out for deciduous trees with a small trunk thickness, it is considered the simplest processing. Exit: unedged elements and slabs.
If there is another woodworking machine, then it is possible to cut up to 65% of the material to produce edged boards of the same width. First, a two-edged timber and boards are sawn from the sides, and then a certain amount of edged lumber is obtained from the timber.
More specific methods are sector and segment sawing. The number of elements in the first method varies from 4 to 8, and depends on the thickness of the trunk. After separation, elements are sawn from each sector along a tangential or radial line. The second method begins with the exit of the beam from the central part, and boards are sawn from the side segments in a tangential direction.
For individual sawing of wood, the circular method is suitable. It is based on turning the log along the longitudinal line by 90° after each sawn board. This allows you to monitor the quality of wood and timely remove the affected areas of the trunk.

Handmade: chainsaw application

For home cutting of several trunks, it is not advisable to purchase a tool whose cost is several times higher than the price of finished products. If you have the necessary skill, then it is more efficient and cheaper to do all the necessary work with a conventional chainsaw, or chain equipment powered by electricity. Of course, such work requires much more physical costs and time, but the price of the issue is significantly reduced.

Garden work needs pruning fruit trees, and it also becomes possible to additionally produce material for outbuildings without resorting to the services of specialists, so that any zealous owner would prefer to buy a chainsaw. Most often, conifers are harvested for the home, and this tool does an excellent job of sawing them. Thanks to even trunks, it is easier to outline the cut lines, which increases the speed of work. Professionals, by the way, most often use a chainsaw, since it is more powerful than an electric one and you can use it anywhere, regardless of whether there is a cutting or sawing of power supplies at the site.

To work with a chainsaw on cutting logs, you will need such a device as a nozzle on the saw, as well as saw cut guides and base-trunk fixers. The nozzle in the form of a frame is attached to the tool so that it remains possible to adjust the distance between the chain and the frame itself. This is done to enable the output of finished lumber, different in thickness. For the role of the guide, you can take either a profile of the desired length, or a flat wooden plank with sufficient rigidity. A special chain is selected for the tool, designed to cut the trunk along. Its difference from the rest is in the teeth, sharpened at a certain angle.

Before starting work, it is necessary not only to prepare all the necessary tools. Regardless of whether a woodworking machine or a manual device is intended for processing the trunk, the first step is to familiarize yourself with the cut map. This is done in order to minimize the percentage of waste, and increase the yield of useful products.

The first thing you need to worry about when ripping is the uniform density of the finished boards. To do this, a competent sawmiller directs the tool from the east side of the log to the west, or in the opposite direction. This is due to the greater density of round timber in its northern part than in the southern.

Next, the slab is removed from both sides with a chainsaw in such a way as to obtain a two-edged beam. It, in turn, is sawn in accordance with the sawing scheme chosen at the beginning of the work. The output gives an unedged board. If there is a certain percentage of defects in the trunk, then a circular cut is possible with the trunk turning at a right angle or 180 °.

Quantity of finished material, cut price

Output useful material with coniferous and hardwood differs in percentage terms. For lumber obtained from coniferous trees, are characterized by the following indicators:

provided that the operation is carried out by a professional and a sawmill is used, the percentage of finished wood will be the highest (80-85%);
edged material, which is given by machines, averages 55-70%;
unedged board when working with a chainsaw leaves up to 30% of waste.

The figures are given without taking into account the finished rejected wood, the amount of which can reach 30%. However, such material is used for products that allow a certain marriage.

Finished wood products after sawing

Deciduous round timber gives 60% of the finished unedged wood and about 40% of the trimmed wood. This is due to the initial curvature of the round timber. You can increase the amount of products received: this will require woodworking machines of various kinds. A certain kind of fixture can increase the amount of lumber by 10-20%. For one cube of lumber, you will need about 10 cubes of hardwood round timber. Installation price additional equipment will pay off the cost of the finished wood. Special lines give more volume, but their use is advisable only on a large area. The average price of sawing wood at a conventional sawmill will be approximately 150-180 rubles per cubic meter of boards.

sawing map

The sawing map is a calculation of the optimal amount of finished lumber from one log. It can be calculated independently for each specific log diameter, or you can use computer program, which greatly facilitates the calculation, and the price of which is quite affordable.

Material yield after sawing wood

Or the source can be a regular guide to sawmilling. The result is a table that is taken as a basis. The sawmill must always be oriented to its data, in order to obtain more lumber of any kind of wood.

In this article we will talk about how cutting logs is performed on a band sawmill. In addition, we will consider what are the criteria for selecting one or another method of wood processing and how this affects the characteristics of finished lumber.

Methods for cutting logs to obtain various lumber have been developed and improved for a long time, since this is the only way to get an edged board, timber and other categories of similar products from a solid tree trunk.

An example of what can be obtained from a regular log

For a long time to this day, wood processing methods have evolved, and in addition, new, more productive equipment has appeared that allows you to get the necessary lumber quickly and with a minimum amount of production waste.

Features of wood processing

Cutting chart for automated wood processing

The instruction for processing raw materials and obtaining sawn products consists of a number of technological operations, including longitudinal cutting of logs, sawn timber trimming and cutting to width, sorting by standard sizes, sorting by workmanship quality, drying and storage.

Each of these stages is important in terms of the quality of the finished product. But, it is cutting that is the most time-consuming and responsible stage, during which the main characteristics of finished lumber are formed.

The scheme of cutting, common sawn products

Drawing up a plan for cutting logs into lumber (selection suitable way processing) depends on the type of wood, on the standard sizes of raw materials, on the degree of humidity, on the density and hardness, and on many other factors. Of course, the method of processing raw materials is largely determined based on the level of technical equipment of the enterprise.

Consider what equipment is used for industrial sawing of wood and what methods are relevant for each category of this equipment.

Equipment for cutting and features of its application

An example of wood processing with group circular saws

The following categories of equipment are used for longitudinal cutting of logs:

Single band or circular (circular) saws - traditional solution used for a long time.
The group of frame saws is a more progressive solution that allows you to significantly increase the productivity of raw material processing without compromising the quality of the finished product.

Let us consider in more detail the features of the use of the listed categories of equipment.

Individual sawing is a method in which single saws are used. In this case, only one cut can be obtained in one pass of the saw. Therefore, the entire tree trunk can be cut in several passes.

Important: The advantage of individual sawing is the independence of each subsequent cut from the previous one.
That is, sawing can be carried out in different planes.
As a result, it becomes possible to more rationally use certain properties of different parts of the log.

At the same time, this method is inefficient, and therefore not suitable for use in large woodworking enterprises.

Group sawing is a technological process during which a group of frame saws is used.
advantage this method is that the log is cut completely in one pass. This saves time and, as a result, reduces the cost of production. But you need to remember that group sawing is performed in one plane.
To date, the following categories of equipment for group sawing are most widely used:

narrow-clear vertical frames, machines with circular saws, milling saws (diameter of processed raw materials from 14 to 22 cm).
medium-light vertical frames (diameter from 24 to 48 cm)
wide-clear vertical frames, double and quadruple band saw units (diameter of processed raw materials over 50 cm).

The main methods of longitudinal sawing

It looks like a table for cutting logs on a band sawmill

So, now that we have considered the current methods of processing wood raw materials using special equipment, we will consider the features of the implementation of these methods.

In the modern woodworking industry, the following cutting methods are used:

"Razval" - a method of sawing logs, in which the cut planes are parallel to each other. In accordance with the location of the lumber in the log, the core board or timber is distinguished; central boards, one of the planes of which runs along the longitudinal axis of the log; side boards.

The photo shows a tree trunk installed in a slitting machine

Important: This method of processing wood raw materials is considered the simplest and least laborious.
But you need to take into account that the finished wooden boards are unedged, and therefore you will additionally have to make a cross section of the log.

"With a bar" - the method allows you to get a bar with two edges. The remainder of the log is sawn into unedged side boards and a strip. That is, cutting is performed not in one, but in two passes. Moreover, the type of saws used for the first and second pass differ both in the number of cutting surfaces and in their direction.

Band saw cutting edge

The equipment on which the timber is made is called the first row machine, and the equipment by means of which the timber is cut into individual boards is called the second row machine.

The “sectoral” method, during which the log is cut into separate sectors, from which boards are subsequently made.
Sawing according to this method is performed in one pass, when the cutting tools go sequentially or in several passes, when longitudinal sectors are obtained at the initial stage, and at subsequent stages these sectors are divided into lumber.
The sector method is relevant for the manufacture of radial and tangential sawn timber. According to the log diameter and the required dimensions of the workpiece, sawing is performed only into quarters or into quarters, followed by cutting into smaller sectors.
The disadvantages of this method include labor intensity, since the log cutting map is compiled individually. In addition, when processing wood raw materials, it turns out a large number of waste.
The segmental method involves sawing the trunk into longitudinal segments, which, in turn, are cut into boards of the required size.
The segment-breaking method involves the simultaneous manufacture of segments and sawing them into lumber of the required size in one pass
Segment-beam method, in which the side segments are simultaneously sawn out, while a two-edged beam is obtained from the middle (central) part.
The method involves cutting in two passes. During the first pass, the log is divided into cant and side segments. During the second pass, the segments are divided into smaller boards.
Circular sawing involves the processing of a log, in which the boards are sawn off sequentially. During processing, the workpiece rotates around its axis, after the next board is sawn off.
Due to the complexity and individual approach, circular sawing is practically not used on an industrial scale.
The aggregate method involves preliminary milling wooden log, after which the resulting beam with square section cut into the required number of boards. During milling, a large amount of technological chips are formed, which, in turn, are used for the manufacture of chipboard or fibreboard.

Features of cross cutting

The most common configuration of crosscut saws

The cross section of a log is called trimming and is performed with special circular saws. Despite the fact that the price of sawn timber increases due to trimming, this stage is mandatory in the course of industrial wood processing. Cross-cutting is performed at the end of the longitudinal sawing of the log.

Lumber, after drying, often have simple, transverse and wavy curvature. Such deformations with their own hands are difficult to correct. To reduce the degree of deformation of the lumber, trimming is performed, during which the part of the wood that has undergone warping is simply cut off.

Automated cutting line for lumber

To perform these works, a cross-cutting machine is used in the form of a frame with a saw with a lower location. During cross-cutting, technological waste is generated, which can be processed into chips and used for the manufacture of particle boards. The location of the cut is determined in accordance with the type of assortment and taking into account the defects of the processed lumber.

Ways to perform cross cutting

Trimming machine in an industrial workshop

Currently, domestic and foreign manufacturers produce a wide range of trimming machines.

In accordance with the configuration of the equipment and the degree of its automation, several options for trimming can be performed:

Trimming beams and boards in a stack at a given constant length. This option is used in the manufacture of various joinery products (doors, windows, stairs, etc.), glued laminated timber and structural elements for wooden housing construction.
Trimming boards with different lengths. During this technological process boards are fed to the working tool, where they are automatically measured. Next, the control unit selects the optimal combination of workpieces that can be cut in one pass in accordance with the specified specification.
Facing with the removal of defects with a variable length of the finished product. This set of equipment allows minimizing the volume of knots, rot, pigment spots and mechanical deformations by cutting off problem areas from the end of the workpiece.
This option is widely used in the manufacture of furniture facades, where gluing of lamellas is allowed to obtain a solid slab. The choice of this trimming option allows to reduce the amount of production waste to a minimum and thus reduce the cost of the finished product.
Facing with removal of defects at fixed standard sizes of finished products. In this case, all blanks are cut to the same length in accordance with the specification.

Taking into account the peculiarities of the technological process, it should be noted that the products obtained in this way are the most expensive, since a large amount of waste remains.

Output

Now we have a general idea of how and with what equipment industrial wood processing is performed. Are there any questions that need clarification? In this case, we recommend watching the video in this article.