Cutting slab and sheet materials. Calculation of wood materials

In the production of wood products, slab, sheet and roll semi-finished products from wood materials are widely used, manufactured in accordance with the requirements of the standards for them. The standard formats of these materials received by enterprises are cut into blanks required sizes. The main limitations when cutting slabs and sheet materials are the number and dimensions of the workpieces. The number of standard sizes of blanks must correspond to their completeness for the production of products provided for by the program. Cutting slab and sheet materials in relation to the organization of the intended purpose of the resulting blanks is usually divided into three types: individual, combined and mixed. With individual cutting, each semi-finished product format is cut into one standard size of the workpiece. With a combined type of cutting, you can cut out several different standard sizes of workpieces from one format. With mixed cutting, it is possible to use individual and combined cutting options for various cases. The efficiency of cutting based on the rational use of materials is assessed by the yield coefficient of blanks.

Particle boards and fibreboards are widely used in the production of wood products. Organizing their rational cutting is the most important task modern production. An increase in the yield rate of particle board blanks by 1% in the overall result of their consumption is expressed by saving millions of cubic meters of boards, the efficiency in monetary terms will amount to millions of rubles.

The efficiency of cutting depends on the equipment used and the organization of the process of cutting slabs and sheet materials. Based on the technological features, the equipment used for cutting slabs can be divided into three groups.

The first group includes machines with several supports rip sawing and one - transverse. The material to be cut is placed on a carriage table. When the table moves in a straight direction, the rip sawing supports cut the material into longitudinal strips. The carriage has adjustable stops, the action of which on the limit switch causes the carriage to automatically stop and drive the transverse sawing support into motion.

The second group includes machines that also have several longitudinal sawing supports and one transverse sawing, but the carriage table consists of two parts. When cutting longitudinally, both parts of the table form one whole, and when moving backwards, each part moves separately until the stop position determines the position of the cross cut. In this way, the alignment of the transverse cuts of the individual strips is achieved.

The third group includes machines that have one longitudinal sawing support and several transverse sawing supports. After each stroke of the longitudinal sawing support, the strip on the movable carriage is fed for cross cutting. In this case, those calipers that are configured to cut a given strip are activated. The rip sawing support can perform a non-through cut (trimming). In addition, there are single-saw format-cutting machines.

1. The first group of equipment is focused on performing the simplest individual cuttings. This gives a low material utilization rate. When implementing more complex patterns after longitudinal cutting, it becomes necessary to remove individual strips from the table with their further accumulation for subsequent individual cutting. At the same time, labor costs increase sharply and productivity decreases.

2. The second group allows you to perform cutting patterns with a variety of stripes equal to two. With a large variety of types, the same difficulties arise as in the first case.

3. The third group allows you to cut more complex patterns with up to five different types of strips. This group of equipment has high performance and is the most promising.

Cutting line for sheet metal and slab materials MRP is intended for cutting wood sheet and board materials into blanks in furniture and other industries.

Cutting is performed with one longitudinal and ten cross-cut saws. The original feeding device allows you to remove a stack of several sheets of material from the stack and simultaneously feed it to the cutting tool. During the feeding and processing process, the bundle being cut is in a clamped state. Packs are served with increased speed, sharply decreasing when approaching the working position. All this ensures high productivity and increased accuracy of material cutting. Special electrical interlocks make work on the line safe and protect the line mechanisms from damage. When the line is disconnected, electrothermodynamic braking of the cutting tool spindles occurs. Furniture factories use automatic feed machines with one longitudinal and ten cross-cut saws. This machine can be used for cutting according to five programs. Crosscut saws are set to the program manually. The minimum distance between the first and second cross-cut saws (left in the feed direction) is 240 mm. Between the other saws minimum distance 220 mm. The machine can simultaneously cut two slabs in height with a thickness of 19 mm or three slabs with a thickness of 16 mm each. The rip saw cuts according to the programs should be made with a consistent reduction in the optimal strips. For example, the first cut is 800 mm, the second is 600, the third is 350, etc.

The slabs are laid transversely on the loading table and aligned along a movable stop ruler. By pressing the handle located under the work table, the longitudinal saw is brought into working position, and it cuts the first strip of the slab package. During the working stroke, the cut strip is placed on the lever and clamped with pneumatic clamps, which makes it impossible to shift the cut. After making a longitudinal cut, the saw goes under the table and returns to its original position. When the rip saw is lowered, the movable table located behind it rises above the level of the lever and receives the cut strips. The table then moves in a transverse direction. The leftmost saw, installed permanently, cuts the edge of the slab (10 mm) to create the base. The remaining cross cuts are performed according to the selected program. The cut blanks are served on an inclined plane and placed in piles. Then the cutting cycle is repeated according to the selected programs. Using an automatic machine, you can perform transverse and longitudinal sawing of particle boards in a stack up to 80 mm high according to a pre-set program. The machine is equipped with separate support tables. Each part of the table can be separately driven, which is necessary for mixed cutting. Cross cuts are made after the table parts are aligned along the cross cuts. Cross cut through the entire width of the slab. When cutting slabs with through cross cuts, all parts of the table are connected and work synchronously. The table is loaded using a loading device. The packages placed by the loader are aligned in length and. width automatically. The aligned package is clamped onto the table trolley by automatically closing clamping cylinders and fed to the rip saws or crosscut saw depending on the installed program. The saws rotate in opposite directions in such a way that the scoring saw works with a downstream feed, and the main saw with a counter feed. The scoring saw has adjustable movement in the axial direction for precise installation relative to the main saw blade. When cutting slabs on this machine, an accurate cut is obtained without chipping even very sensitive material on the edges. There are semi-automatic machines that also use scoring saws, but the translational movement during cutting is performed by the saw unit while the plate is stationary. The workpieces are moved either manually until they stop against the limiting ruler, or by a carriage, the positions of which are set using adjustable stops (in accordance with the width of the longitudinal grooves) and limit switches. This machine is used for format cutting of laminated panel materials and those lined with plastic. The cutting accuracy is up to 0.1 mm. The productivity of the machine when cutting particle boards to the required format is 5.85 m3/h. On the machine instead of organs manual control To feed material during longitudinal cutting, you can install an automatic pusher, which is controlled by an electronic device. The latter is programmed to perform certain cuts using a saw blade of the required thickness. When cutting particle boards, circular saws with a diameter of 350-400 mm with hard alloy plates are used. The cutting speed is 50-80 m/s, the feed per saw tooth depends on the material being processed, mm: particle boards 0.05-0.12, fiberboards 0.08-0.12, plywood for longitudinal cuts 0.04 -0.08, plywood for cross cutting up to 0.06. Cutting cards. To organize rational cutting of slabs, sheets and roll materials technologists develop cutting maps. Cutting cards represent graphical representation arrangement of workpieces on the standard format of the material to be cut. To draw up cutting maps, you need to know the dimensions of the workpieces, the formats of the material to be cut, the width of the cuts and the capabilities of the equipment. Particle boards arriving at the plant usually have damaged edges. Therefore, when developing cutting maps, it is necessary to provide for preliminary filing of the slabs to obtain a base surface along the edge. If the workpieces are cut out with an allowance that provides for their filing around the perimeter in further operations, then such filing of the edges of the slabs can be eliminated. When developing cutting maps, it is necessary to specifically take into account all the features of the supplied materials. All blanks cut from it are placed on a scale on the format of the material to be cut. If veneered material, laminated boards, plywood and similar wood materials are cut, then when drawing up cutting maps it is necessary to place the workpieces on the format, taking into account the direction of the fibers on the cladding. In this case, the workpieces have a definite size along and across the fibers. Drawing up cutting plans for a large enterprise is an important, complex and time-consuming task. Currently, methods have been developed for drawing up cutting maps for slab, sheet and roll materials with simultaneous optimization of the cutting plan. Optimal plan cutting is a set various schemes cutting and the intensity of their use, ensuring completeness and a minimum of losses for a certain period of operation of the enterprise. When drawing up cutting plans, only those acceptable options are left that ensure the yield of workpieces is not less than the established limit (for wood-based panels 92%). The procedure for optimizing the cutting process is complex and is solved using a computer Rykunin S. N., Tyukina Yu. P., Shalaev V. S. Technology of sawmill and woodworking industries: Tutorial. - M.: MGUL (Moscow State Forestry University) - 2005 - p. 198.

Consequently, the process of cutting slab sheet and roll materials is simpler than boards, since when cutting them there are no restrictions on quality, color, defects, etc., they are stable in quality and format.

Cutting slab and sheet materials. In the production of wood products, slab, sheet and roll semi-finished products from wood materials are widely used, manufactured in accordance with the requirements of the standards for them. The standard formats of these materials received by enterprises are cut into blanks of the required sizes.

The main limitations when cutting slab and sheet materials are the number and size of the workpieces.

The number of standard sizes of blanks must correspond to their completeness for the production of products provided for by the program. Cutting slab and sheet materials in relation to the organization of the intended purpose of the resulting blanks is usually divided into three types: individual, combined and mixed.

With individual cutting, each semi-finished product format is cut into one standard size of the workpiece. With a combined type of cutting, you can cut out several different standard sizes of workpieces from one format. With mixed cutting, it is possible to use individual and combined cutting options for various cases. The efficiency of cutting based on the rational use of materials is assessed by the yield coefficient of blanks.

Particle boards and fibreboards are widely used in the production of wood products. Organizing their rational cutting is the most important task of modern production. An increase in the yield rate of particle board blanks by 1% in the overall result of their consumption is expressed by saving millions of cubic meters of boards, the efficiency in monetary terms will amount to millions of rubles. The efficiency of cutting depends on the equipment used and the organization of the process of cutting slabs and sheet materials.

Based on the technological features, the equipment used for cutting slabs can be divided into three groups. The first group includes machines that have several supports for longitudinal sawing and one for transverse sawing. The material to be cut is placed on a carriage table. When the table moves in a straight direction, the rip sawing supports cut the material into longitudinal strips. The carriage has adjustable stops, the action of which on the limit switch causes the carriage to automatically stop and drive the transverse sawing support into motion.

This gives a low material utilization rate. When implementing more complex patterns after longitudinal cutting, it becomes necessary to remove individual strips from the table with their further accumulation for subsequent individual cutting. At the same time, labor costs increase sharply and productivity decreases. 2. The second group allows you to perform cutting patterns with a variety of stripes equal to two. With a large variety of types, the same difficulties arise as in the first case. 3. The third group allows you to cut more complex patterns with up to five different types of strips. This group of equipment has high performance and is the most promising.

The MRP cutting line for sheet and slab materials is designed for cutting wood sheet and slab materials into blanks in furniture and other industries. Cutting is performed with one longitudinal and ten cross-cut saws. The original feeding device allows you to remove a stack of several sheets of material from the stack and simultaneously feed it to the cutting tool.

During the feeding and processing process, the bundle being cut is in a clamped state. The packs are fed at an increased speed, which decreases sharply when approaching the working position. All this ensures high productivity and increased accuracy of material cutting. Special electrical interlocks make work on the line safe and protect the line mechanisms from damage.

When the line is disconnected, electrothermodynamic braking of the cutting tool spindles occurs. Furniture factories use automatic feed machines with one longitudinal and ten cross-cut saws. This machine can be used for cutting according to five programs. Crosscut saws are set to the program manually. The minimum distance between the first and second cross-cut saws (left in the feed direction) is 240 mm. The minimum distance between other saws is 220 mm. The machine can simultaneously cut two slabs in height with a thickness of 19 mm or three slabs with a thickness of 16 mm each.

The rip saw cuts according to the programs should be made with a consistent reduction in the optimal strips. For example, the first cut is 800 mm, the second is 600, the third is 350, etc. The slabs are laid crosswise on the loading table and aligned along a moving stop ruler. By pressing the handle located under the work table, the longitudinal saw is brought into working position, and it cuts the first strip of the slab package. During the working stroke, the cut strip is placed on the lever and clamped with pneumatic clamps, which makes it impossible to shift the cut.

After making a longitudinal cut, the saw goes under the table and returns to its original position. When the rip saw is lowered, the movable table located behind it rises above the level of the lever and receives the cut strips. The table then moves in a transverse direction. The leftmost saw, installed permanently, cuts the edge of the slab (10 mm) to create the base. The remaining cross cuts are performed according to the selected program.

The cut blanks are served on an inclined plane and placed in piles. Then the cutting cycle is repeated according to the selected programs. Using an automatic machine, you can perform transverse and longitudinal sawing of particle boards in a stack up to 80 mm high according to a pre-set program. The machine is equipped with separate support tables.

Each part of the table can be separately driven, which is necessary for mixed cutting. Cross cuts are made after the table parts are aligned along the cross cuts. Cross cut through the entire width of the slab. When cutting slabs with through cross cuts, all parts of the table are connected and work synchronously. The table is loaded using a loading device. The packages placed by the loader are aligned in length and. width automatically. The aligned package is clamped onto the table trolley by automatically closing clamping cylinders and fed to the rip saws or crosscut saw depending on the set program. The saws rotate in opposite directions in such a way that the scoring saw works with a downstream feed, and the main saw with a counter feed.

The scoring saw has adjustable movement in the axial direction for precise installation relative to the main saw blade. When cutting slabs on this machine, an accurate cut is obtained without chipping even very sensitive material on the edges.

There are semi-automatic machines that also use scoring saws, but the translational movement during cutting is performed by the saw unit while the plate is stationary. The workpieces are moved either manually until they stop against the limiting ruler, or by a carriage, the positions of which are set using adjustable stops (in accordance with the width of the longitudinal grooves) and limit switches. This machine is used for format cutting of laminated panel materials and those lined with plastic.

The cutting accuracy is up to 0.1 mm. The productivity of the machine when cutting particle boards to the required format is 5.85 m3/h. On the machine, instead of manual controls for feeding material during longitudinal cutting, you can install an automatic pusher, which is controlled by an electronic device. The latter is programmed to perform certain cuts using a saw blade of the required thickness.

When cutting particle boards, circular saws with a diameter of 350-400 mm with hard alloy plates are used. The cutting speed is 50-80 m/s, the feed per saw tooth depends on the material being processed, mm: particle boards 0.05-0.12, fiberboards 0.08-0.12, plywood for longitudinal cuts 0.04 -0.08, plywood for cross cutting up to 0.06. Cutting cards. To organize rational cutting of slab, sheet and roll materials, technologists develop cutting maps.

Cutting cards are a graphical representation of the location of workpieces on a standard format of the material being cut. To draw up cutting maps, you need to know the dimensions of the workpieces, the formats of the material to be cut, the width of the cuts and the capabilities of the equipment. Particle boards arriving at the plant usually have damaged edges. Therefore, when developing cutting maps, it is necessary to provide for preliminary filing of the slabs to obtain a base surface along the edge. If the workpieces are cut out with an allowance that provides for their filing around the perimeter in further operations, then such filing of the edges of the slabs can be eliminated.

When developing cutting maps, it is necessary to specifically take into account all the features of the supplied materials. All blanks cut from it are placed on a scale on the format of the material to be cut. If veneered material, laminated boards, plywood and similar wood materials are cut, then when drawing up cutting maps it is necessary to place the workpieces on the format, taking into account the direction of the fibers on the cladding.

In this case, the workpieces have a definite size along and across the fibers. Drawing up cutting plans for a large enterprise is an important, complex and time-consuming task. Currently, methods have been developed for drawing up cutting maps for slab, sheet and roll materials with simultaneous optimization of the cutting plan. The optimal cutting plan is a combination of different cutting patterns and the intensity of their use, ensuring completeness and a minimum of losses for a certain period of operation of the enterprise.

When drawing up cutting plans, only those acceptable options are left that ensure the yield of workpieces is not less than the established limit (for wood-based panels 92%). The procedure for optimizing the cutting process is complex and is solved using a computer. Consequently, the process of cutting slab sheet and roll materials is simpler than boards, since when cutting them there are no restrictions on quality, color, defects, etc., they are stable in quality and format. 3. Composition of auxiliary and service production Auxiliary production is part of the production activity of an enterprise necessary to service the main production and ensure uninterrupted production and release of its products.

The most important tasks Auxiliary production: manufacturing and repair of technological equipment, containers and special tools and supplying the main workshops with them; providing the enterprise with all types of energy, repairing energy, transport and mechanical equipment, control and measuring equipment, care and supervision of them; repair of buildings and structures and household equipment; acceptance, storage and delivery to the workshops of the enterprise of raw materials, materials, semi-finished products, etc. The activities of the transport and storage facilities of the enterprise can be classified as auxiliary production.

Auxiliary production is determined by the characteristics of the main production, the size of the enterprise and its industrial connections.

Auxiliary production is mainly carried out in auxiliary workshops. As part of large plants and associations (for example, metallurgical, chemical, etc.), specialized workshops and enterprises are created to service the main production. A promising direction for improvement is auxiliary production - the transfer of the most critical and labor-intensive part of auxiliary work to specialized enterprises serving the industry of the area.

This makes it possible to use high-performance technology and advanced production methods in auxiliary production, reduce the cost of performing relevant work at enterprises served by specialized repair, tool and other bases, and ensure an increase in labor productivity. As the technical improvement of the main production requires parallel development of auxiliary production and an increase in its technical and organizational level.

At large enterprises and associations, auxiliary production should be developed on the basis of centralization and specialization of work, ensuring its greatest efficiency. The cost of distributed wood and semi-finished products is recorded with a plus sign in other lines, in the lines of main, auxiliary production, and complex expense items where these products are used. Sum positive values distributed expenses must be equal to their excluded negative value.

In the Profit and Loss Statement, general business expenses are reflected as part of the cost of products (work, services) by line. Service industries include: housing and communal services, workshops consumer services, canteens and buffets; children's preschool institutions, rest homes, sanatoriums and other health, cultural and educational institutions that are on the balance sheet of the organization. Direct costs are directly related to the activities of service production.

They are written off to the debit of account 29 “Service production and farms” from the credit of accounts for accounting for inventories, settlements with employees for wages, etc. Indirect costs are associated with the management of service production. They are written off to the debit of account 29 from accounts 23 “Auxiliary production”, 25 “General production expenses” and 26 “General expenses”. Service industries and farms are intended to perform work (provide services) for the needs of the main (or auxiliary) production, for the non-production needs of the organization (dormitories, canteens) or for third-party organizations.

In cases where the enterprise, in addition to structural divisions that directly produce products, also has divisions that perform auxiliary functions, engaged in servicing the main production, the costs of these productions are recorded separately on account 23 “Auxiliary productions”. In particular, productions that carry out following functions: service various types energy (electricity, steam, gas, air, etc.); transport services; repair of fixed assets; manufacture of tools, dies, spare parts, construction parts, structures or beneficiation building materials(mainly in construction organizations); construction of temporary (non-title) structures; mining of stone, gravel, sand and other non-metallic materials; logging, sawmilling; salting, drying and canning of agricultural products, etc. These productions are considered auxiliary only if this type of activity is not the main one.

Accounting for the costs of auxiliary production is carried out by analogy, taking into account the costs of the main production on account 20. The debit of account 23 “Auxiliary production” reflects direct costs associated directly with the production of auxiliary production products, performance of work and provision of services, as well as indirect costs associated with management and maintenance of auxiliary production, and losses from defects.

Direct expenses related directly to the production of products, performance of work and provision of services are written off to the debit of account 23 “Auxiliary production” from the credit of accounts for inventory accounting, settlements with employees for wages, etc. These transactions are recorded accounting entries: Debit of account 23 “Auxiliary production” Credit of account 10 “Materials” - write-off of the cost of materials transferred to auxiliary production for the manufacture of products, performance of work, provision of services; Debit of account 23 “Auxiliary production” Credit of account 70 “Settlements with personnel for wages” - calculation of wages for employees of auxiliary production; Debit of account 23 “Auxiliary production” Credit of account 69 “Calculations for social insurance and security” - accrual of unified social tax and accident insurance contributions on the amount of remuneration of employees of auxiliary production.

Indirect expenses associated with the management and maintenance of auxiliary production are collected in the debit of accounts 25 “General production expenses” and 26 “General business expenses” and are written off to the debit of account 23. Expenses associated with losses from defects in auxiliary production are written off to account 23 from the Credit account 28 “Defects in production”. The amounts of the actual cost of finished products of auxiliary production can be written off from the Credit of account 23 to the Debit of accounts: 20 “Main production” or 40 “Output of products (works, services)” - if the products of auxiliary production are transferred to the divisions of the main production; 29 “Service production and farms” - if the products of auxiliary production are transferred to service production and farms; 90 “Sales” - if auxiliary production products are sold externally or work or services were performed for third parties.

It should be noted that the cost of production of auxiliary production can only include general production expenses, and general business expenses cannot be included, but are distributed directly among the types of products of the main production.

In cases where it is not possible to accurately establish for which divisions products were produced, work was performed or auxiliary production services were provided, these costs are distributed between these divisions in proportion to the amount of direct costs, wages employees, volume of products produced, etc. If necessary, costs are also distributed by type of product. So, auxiliary production is determined by the characteristics of the main production, the size of the enterprise and its production connections, and servicing production is included in the cost of finished products (work, services).

End of work -

This topic belongs to the section:

Sawmill and woodworking production

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Cutting wood materials into blanks is the first stage of mechanical processing. The purpose of cutting is to obtain blanks required sizes, from which parts will be obtained during further processing. Currently, with technological specialization, cutting is carried out in specialized areas of enterprises that manufacture wood materials. With this organization of cutting, transportation volumes are reduced and conditions are created for a more rational use of raw materials. Only useful volumes of blanks are transported to enterprises consuming wood materials; significant volumes of waste generated during cutting are secondary raw materials and can be effectively used for various purposes. The cutting process is organized depending on the type of material being cut, production volumes and the purpose of the workpieces. According to the type obtained during cutting

spring materials, transporting only useful volumes of blanks, significant volumes of waste generated during cutting represent secondary raw materials and can be effectively organized depending on the type of material being cut, production volumes and purpose of blanks. Based on the type of workpieces obtained during cutting, cutting can be made into rough workpieces, which are further processed, and into finishing ones. In the first case, rough bases are used when cutting, in the second, finishing bases and the use of special techniques, equipment and tools are required to ensure the necessary accuracy and quality of processing. Based on the type of materials being cut, cutting of boards, wood boards, sheet and roll materials is distinguished. The rationality of the cutting process is assessed by labor efficiency.

Efficient use of materials when cutting is the most important task of modern production. IN general view the efficiency of material use is assessed by the yield coefficient Kv of workpieces, determined percentage volume, area, molding or mass of the resulting blanks V 3 volume, area of the cut material Vc:

Kv = V 3 /Vc100. (77)

Increasing the yield ratio of blanks is an important and complex problem. The yield of blanks depends on many factors, the main of which are wood defects, structural deviations, natural defects, obvious and hidden, requirements for the quality of blanks and their sizes, qualifications of workers, working conditions, equipment and tools used, etc. For these reasons, cutting boards into blanks is carried out with the direct participation of workers who visually assess the quality of the blanks and compare it with the quality requirements for the parts made from them.

According to the degree of worker participation in monitoring the cutting process, cutting is distinguished between individual and group, and according to its implementation - transverse and longitudinal. Individual cutting is characterized by the fact that it is produced taking into account the size and quality of raw materials according to the most rational scheme. Group cutting is carried out without taking into account the quality of raw materials according to a pre-established scheme.

Group cutting of unspecified lumber reduces the yield of blanks by 7% compared to individual cutting.

Cross-cutting of lumber is carried out by dividing the lumber into pieces of the required length. Longitudinal cutting of lumber involves dividing the material into pieces of the required width or thickness. Depending on the sequence of these technological cutting operations, a general assessment distinguishes between transverse-longitudinal and longitudinal-transverse cutting.

When organizing the cutting of lumber, it is necessary to establish the ratio of the sizes of the existing boards to the dimensions of the workpieces. In this case, the following options are possible: the cross-sectional dimensions of the boards correspond to the cross-sectional dimensions of the workpieces; the width of the boards is equal to the width of the workpieces, but the thickness is a multiple or greater than the thickness of the workpiece; the thickness of the boards corresponds to the thickness of the workpieces, and the width is a multiple of or exceeds the width of the workpieces; the thickness and width of the boards exceed the cross-sectional dimensions of the workpieces or are multiples of them. The length of the workpiece also affects the organization of cutting lumber. If it is not possible to obtain a workpiece of a significant size from the available types of lumber, then during the cutting process technological operations are introduced to glue the sections along the face and edge so that the glued workpieces meet the size and quality requirements for them.

When cutting lumber, you can use a variety of schemes depending on the type of boards, type of wood, size of the workpieces and production conditions. For example:

1. Transverse-longitudinal cutting is carried out in such a way
sequences: trimming boards into segments with cutting
fects: sawing sections into blanks.

2. Longitudinal-transverse cutting - cut the boards first
cut by sawing lengthwise into slats, then trimmed to size
workpiece frames.

3. Trimming the boards into pieces with cutting out defective areas
and subsequent marking of segments and cutting out of them
blanks

5. Milling one or two layers of the board, marking and
then cut according to scheme 1 or 2.

6. Milling of the face, facing into segments with cutting
defective areas, filing edges edged boards, ugh
edge bending and gluing of panels, marking and sawing
curved blanks (see Fig. 57). When using about
carved boards to produce blanks of significant lengths
You can use the cutting diagrams given below.

7. Milling of the face, facing into segments with cutting
defective areas, gluing with a toothed tenon along the length, cali
browing, trimming onto blanks.

8. Trimming the boards, gluing along the length with a toothed tenon,
trimming into measured lengths, milling edges and faces,
gluing the shield, cutting the shield widthwise into blanks, california
preparation of blanks.

9. Cutting the boards into slats, trimming the slats with cutting
fects, gluing slats into a continuous beam, cutting beams into
blanks.

The first six schemes are widely used in the production of furniture and building parts. In Fig. 58 shows examples of cutting unedged boards according to schemes 1, 2 and 6. As you can see,

Rice. 58. Schemes for cutting boards:

A- transverse-longitudinal (scheme 1); b - longitudinal-transverse (scheme 2);

V- after gluing the segments into a shield (diagram 6)

Longitudinal-transverse cutting provides a higher yield of the workpiece due to less loss of material when cutting out defects. It is especially effective for low grades of boards. According to the 2nd scheme, the excess yield of blanks is 3% compared to the 1st scheme.

The use of preliminary marking of the board (scheme 4) increases the yield compared to the 1st scheme by 9%. If the face of the board is milled and this reveals invisible defects, this will further increase the yield of workpieces by 3% compared to scheme 4. In order to better use the usable part of the board, it is advisable to cut on the workpieces different sizes. In this case, it is possible to select the dimensions of the workpieces so as to make full use of the defect-free part of the board. First of all, it is necessary to cut out the longest blanks - the main ones. When visually assessing the quality of boards, the number of standard sizes of workpieces for such cutting is limited by the physiological characteristics of the worker. A qualified worker can change no more than 4-5 standard sizes of workpieces during the cutting process, provided that the difference between their sizes is more than 100 mm.

Increasing the number of standard sizes of workpieces for simultaneous cutting from one board will sharply reduce production

ity and may lead to errors. Machine operator errors during cutting reduce the useful yield of workpieces. The use of additional cutting operations - marking, gluing and milling - increases the cost of workpieces. A comparison of the effectiveness of increasing the yield of workpieces and the growth of labor productivity shows that increasing the yield of workpieces is more effective and corresponds to the directive direction of saving raw materials. The use of gluing when cutting according to scheme 6 increases the yield of curved workpieces by 8-12% compared to scheme 3. Schemes 7, 8 and 9

Rice. 59. Organization of cutting lumber:

A - on the production line; / - drive roller; 2 - cross-cutting machine; 3 - non-drive roller; 4 - emphasis; 5 - belt conveyor; b - pressure roller; 7 - transfer table; 8 - scoring machine; 5 - table; 10 - limit switch; // - power button; 12 - pedal; b, c - on machines TsDKCH-3, LS80-6

changed to obtain blanks for glued building structures up to 80 m long.

When cutting boards into straight pieces, general-purpose circular saws are used, and for curved ones, band saws are used. In specialized cutting shops, in addition, rib dividing machines, multi-saws and knot sealing machines are used.

In Fig. 59 shows a diagram of the design and organization of the workplace of a partially automated cross-cutting machine TsPA40 or TsME-ZA for cutting edged boards into blanks for construction parts. The machine operator throws boards from the stack onto the receiving table of the cross-cutting machine. The receiving table is equipped with driven screw rollers 1, which not only feed the board forward, but also press it against the ruler. The board to be trimmed moves forward along the cantilever non-drive rollers until it stops 4. Having reached this stop, the end of the board presses the limit switch lever 10, stops the electric motor that drives the feed rotors

faces and at the same time turns on the saw feed. Caliper 2 s The saw blade moves forward and cuts the board. During the reverse movement, the saw support, using a system of levers, throws the cut end of the board from the cantilever rollers onto the moving belt conveyor 5 located underneath it and simultaneously turns on the electric drive of the feed drive rollers /.

In addition to automatic, the machine also has manual mechanized control, which the machine operator can use to arbitrarily stop the board at any distance to the stop to cut out defective areas from it. The pedal serves this purpose 12 and switch (button) 11. Pressing the foot on the pedal 12 stops the rotation of the feed rollers, and pressing the button with your hand AND causes cross feed of the saw blade.

The machine can operate as part of a line (as shown in Fig. 59) or independently. The productivity of such a partially automated machine, serviced by one machine operator, is approximately equal to the productivity of a machine serviced by a machine operator with two auxiliary workers, and the work itself is much safer and easier.

The segments are sawn lengthwise into circular saws with mechanical or manual feed. (In line - in positions 6 -9.) Of the machines with mechanical feed, the most advanced for sawing sections into workpieces are mortising machines with caterpillar feed, such as TsDK-4-3 and TsDK-5-2. These machines provide high straightness of the cut without the use of a guide ruler, which is very important when cutting according to markings, when the worker guides the piece into the machine along a pencil mark. However, in most cases, sawing is carried out along a guide ruler, which is installed parallel to the saw blade and at a distance equal to the width of the workpiece. If there is a wane, the first cut is made by eye, and for the second, third and others, the sawn edge is pressed against a ruler.

The machine is serviced by 2 people - a machine operator and an auxiliary worker. The first one controls the machine and feeds the pieces into it, the second one receives them and, if necessary, returns them for re-cutting.

Working on circular saws with manual feed is similar to working on machines with mechanical feed, but is less productive, less safe and requires significant effort on the part of the machine operator when pushing the pieces onto the saw.

The segments are most often cut lengthwise into one size. To increase output, it is rational to cut hardwood for massive parts into two or three sizes in width. In this case, the ruler on the machine is set to the largest width of the workpiece. To cut into narrower pieces without rearranging the rulers, use special

devices or bookmarks, which are bars with shoulders at one end. In Fig. 60 and 61 show diagrams of specialized areas for cutting lumber, working according to cutting schemes 1 and 2.

When cutting lumber, wood loss is determined by three reasons that do not depend on the organization of cutting: 1) natural wood defects and defects depending on the grade of boards; 2) the blanks are not a multiple of the size of defect-free sections of the board, when the distance between the rows of unacceptable knots is less than the length of two blanks; 3) losses in sawdust.

If we designate the coefficients of wood utilization that reflect losses due to these factors, then K d is the utilization coefficient that takes into account losses due to cutting out defects depending on the grade of boards; Kk is a coefficient that takes into account losses due to the non-multiple size of workpieces with defect-free sections of the board; Co-factor taking into account sawdust losses, then the overall output coefficient Kw (Table 11) will be determined as

K v- KdKkKo = Vз / Vс (78)

Sawdust losses depend on the number of cuts and saws used. If cutting is carried out according to three board sizes, then the coefficient Co is determined from the ratio

K v- K / oK // kK /// o, (79)

where Ko- takes into account losses during cross-cutting K / o and K // o K /// o – respectively, longitudinal and edge.

The yield of workpieces largely depends on the grade of raw materials and the size of the workpieces. Increasing the length of workpieces by 1 m reduces their yield by approximately 5%. The norms for the useful yield of furniture blanks are given in table. 12.

The yield of complete blanks decreases with the deterioration of the varietal composition of lumber.

When cutting boards into curved pieces, band saw machines with a narrow saw blade (up to

11. VALUE OF THE TOTAL YIELD COEFFICIENT Kv

Rice. 60. Area for transverse-longitudinal cutting of boards:

/ - elevator; 2 - cross-cutting machine; 3 - cutting machines; 4 - conveyor;

5-automatic knot sealer; 6 - packing table; 7 - sorting device; IN - package of boards; 9 - dividing machine

Rice. 61. Section of longitudinal-transverse cutting of boards:

/ - cutting machine; 2 - dividing machine; 3, 7 - cross-cutting machines;

4-automatic knot sealer; 5 - sorting device;

6 - packing table

12. NORMS OF USEFUL YIELD OF BLANKETS WHEN CUTTING TIMBER IN FURNITURE PRODUCTION

40 mm). The width of the saw blade is selected depending on the minimum radius of curvature of the workpiece. The smaller the radius of curvature of the workpiece, the narrower the saw blade should be. The minimum radius of curvature of the workpiece, depending on the width of the saw band and its spread, is determined by the formula

Rmin = 0.12V 2 /b, (80)

where Rmin is the minimum radius of curvature of the workpiece, mm; B - saw blade width, mm; b-set of saw teeth to one side, mm.

Uz =(0.05-0.1) s, mm, (81)

where S – saw thickness, mm.

The feed rate is determined by the formula

U = [(0.05 – 0.1) s 60υ], m/min, (81)

Where u is the feed speed, m/min; S – saw thickness, mm; υ – cutting speed, m/s; t-teeth pitch, mm.

The average accuracy of blanks when cutting boards is given in table. 13.

Automation of the process of cutting lumber causes difficulties in that it requires a visual assessment of the quality of the materials being cut and coordination of this assessment with the requirements for the quality of the workpieces and their sizes. The application of the principles of power sorting of lumber, taking into account the purpose of the resulting blanks, allows us to overcome these difficulties.

It is possible to create automated system cutting lumber with a microprocessor that takes into account the dimensions of the workpieces and their physical and mechanical characteristics, determined during cutting.

There are also optical devices that record the size of natural wood defects that can absorb light flux (knots, cracks, gils, etc.). Such devices can manage cutting defects automatically.

Technological operations for cutting sheet and slab materials include sawing them lengthwise and crosswise to obtain blanks or parts of the required sizes. In this case, it is necessary to fulfill the main requirements for cutting - ensuring the maximum cutting ratio, completeness of workpieces in accordance with the volume of production and the corresponding quality. The maximum percentage of useful yield of clean parts can be ensured if the allowances are minimal, organizational and technological losses are reduced to zero, and the cutting of slab and sheet materials into blanks is based on strict mathematical calculations.

In production, blanks from slab and sheet materials are cut according to cutting cards. When developing cutting maps, strict adherence to the maximum yield of parts, the completeness of parts of different sizes and purposes in accordance with the volume of production, the maximum number of standard sizes of parts when cutting one plate and the minimum repetition of the same parts in different maps cutting Cutting maps are drawn up taking into account allowances for subsequent machining. For furniture blanks made of slab materials, processing allowances are set along the length and width. When drawing up cutting plans lined with chipboard, take into account the direction of the pattern in the workpieces.

The equipment used in furniture and woodworking enterprises for cutting slabs implements a step-by-step cutting scheme, in which, at the first stage, chipboard is cut lengthwise into strips, then, at the second stage, the strips are cut into blanks. Depending on the number of standard sizes of workpieces included in the cutting card, and whether or not the completeness of the workpieces in one cutting card is complied with, individual, combined and joint cutting methods are distinguished.

In individual cutting, materials (slabs) of one type are cut into blanks of one type, or materials of one type are cut into blanks of several types (several standard sizes) and, finally, materials of several types are cut into blanks of the same type. The individual cutting method is accompanied by a large amount of waste.

Combined cutting involves the inclusion in each cutting card of several standard sizes of blanks or parts with mandatory compliance with the completeness of the cut blanks. This cutting method is, as a rule, more effective than individual cutting, but it is more complex.

Joint cutting can include individual and combined cutting methods and is the most effective compared to those considered.

The most widely used machines for cutting unlined chipboard are such machines as TsTMF-1, TsTZF-1 (Russia) (Fig. 67); for cutting laminated chipboard - format-cutting machines ITALMAC Omnia-3200R (Fig. 68), CASOLIN Astra SE400 (Italy), ROBLAND (Belgium), PANHANS (Germany) and cutting centers with numerical control SELCO EB 120 (Fig. 69 ), Biesse SELCO WNAR600 (Italy), HVP 120 (Fig. 70), etc.

Rice. 67. Format-edging machine TsT3F-1: 1-bed; 2-guide; 3-control panel; 4-hydraulic station; 5-hydraulic drive of the transverse caliper; 6-traverse; 7, 12-calipers; 8, 11-flywheels; 9-saw for longitudinal sawing; 10-saw for cross cutting; 13-cable; 14-cut material; 15-carriage

Rice. 68. Format cutting machine ITALMAC Omnia-3200R

Rice. 69. CNC cutting machine SELCO EB 120

Rice. 70. CNC vertical cutting center HVP 120

Accompanied by waste in the form of sawdust and lump waste: shavings, end sections and sections of material with elements of removed defects and defects. The choice of method depends on the degree of processing of lumber (edged and unedged), their quality and condition (dry and raw).

Raw lumber is cut into blanks much less frequently. This is explained by the fact that when forming the dimensions of the workpieces, allowances are required for shrinkage and removal of its defects (partial warping and end cracks). Laying lumber in drying piles and drying itself are simpler operations compared to stacking and drying header.

The production of blanks from edged and unedged lumber differs in that the former have a formed cross-section, so their cutting does not involve operations to remove the running strip, and this makes it possible to reduce wood waste. The degree of use of edged and unedged boards is determined by the type of blanks obtained (timber, panel), their sizes and quality group. Receipt the largest number workpieces of specified sizes and quality at minimum consumption lumber is provided the right choice way of cutting them.

Transverse method cutting lumber - this is the simplest method of cutting lumber, in which the length of the blanks is formed and defects are cut out. This method is used to cut edged lumber, the cross-section of which coincides with the cross-section of future workpieces, or workpieces that have a free width. The transverse method of cutting lumber is used in milling shops in the production of floor boards and molded products, as well as glued structures.

Cutting unedged boards using this method is carried out in cases where they are trimmed after drying (cleaning the ends) or if they are obtained from the rung zone of the log and have a ash part in the apical end, which is removed before drying.

With the transverse method of cutting lumber, waste is generated: in the form of end sections and defective places, pieces of wood (often defect-free) resulting from the non-multiplicity of the lengths of blanks and lumber, as well as sawdust. The transverse method of cutting lumber is most effectively used in combination with the longitudinal one.

Transverse-longitudinal method Edged and unedged lumber is cut, the length of which is first formed, and then the width. With this cutting method, waste occurs in the running and wane lath when cutting unedged boards and waste due to the non-multiple width of unedged and edged boards, as well as sawdust.

When cutting raw lumber, when creating the width, allowances for shrinkage must be taken into account. This method of cutting lumber is used in the production of blanks for joinery and construction products, furniture and containers, as well as sections for parquet panels.

Longitudinal-transverse method of cutting lumber characterized by the alternate formation of the width and length of the workpieces with the simultaneous cutting out of defects. With this cutting method, there are losses due to the non-multiple width and length of blanks and lumber, as well as waste into sawdust. Allowances for shrinkage are taken into account only when forming the width. This method produces the bulk of long workpieces and defect-free sections that are used for gluing. Wood waste when cutting out defects is minimal, since the width of the cut is equal to the width of the workpiece.

Transverse-longitudinal-transverse method of cutting lumber characterized by the fact that edged and unedged lumber is first cut into several multiple length segments with simultaneous cutting out of defects if they run along the entire width or coincide with the cut. After that, each segment is cut along the width, and then again along the length with cutting out defects. With this cutting method, losses are possible due to the non-multiplicity of the length and width of lumber and blanks, as well as sawdust waste, allowances for shrinkage are taken into account when forming the width of the blanks. This method produces blanks for furniture parts and joinery and construction products, as well as blanks for gluing.

The use of the transverse-longitudinal-transverse cutting method is also effective when cutting lumber that is warped along the edge. The first transverse cut significantly reduces the effect of warping on the shape of the board and thereby increases the length of defect-free sections. When producing thin blanks from thick lumber, the edge cutting method (thickness cutting) is used, which is carried out on circular saws or band saws.

A valid assessment of the effectiveness of lumber cutting methods is the volumetric and value yields of the workpieces, which are most often expressed as a percentage. The volumetric yield of blanks is determined as the ratio of the volumes of blanks received and sawn timber cut.

The value yield of blanks takes into account the varietal composition of the resulting blanks, as well as the products that are obtained when cutting blanks and have a price, i.e. is commercial products(chips, sawdust, short pieces). Each type of product, in accordance with its grade or quality group, is assigned a value coefficient, which, together with the percentage of volumetric yield, constitutes the value yield. An increase in the value yield of workpieces is most often accompanied by a decrease in the volumetric yield of workpieces, which is compensated by the production of higher quality products, and therefore more expensive ones.