The basis for further technical progress in sawmill and woodworking production - mechanization and automation of production processes, aimed at solving one of the important tasks - replacing manual labor work of mechanisms and machines.
Mechanization is the replacement of manual labor with machine labor. In this case, the machine performs work that was previously performed by a person with the help of muscular strength.
However, during the operation of this machine, a person cannot move away from it, since he must perform a number of auxiliary operations, without which the machine ceases to perform its functions. Sometimes the performance of such a machine is limited by the physical capabilities of a person and it is not fully utilized.
The working machine (non-automated) has, as a rule, the mechanisms of working strokes and performs mainly the main working movements. Auxiliary operations, such as loading workpieces, clamping, etc., are performed by a person. In this case, the entire production process is based on the interaction of man and machine. The sequence (program) of performing operations is chosen by the person himself.
Automation is a higher stage in the development of machine production, in which a person is freed not only from manual labor, but also from the responsibilities of the operational management of the mechanisms that carry out the production process. There is no need for continuous maintenance of an automatic machine, and a person can move away from it, since it itself performs all the main and auxiliary operations production process... The performance of such a machine is not related to the physical capabilities of a person, therefore, it can reach a high level.
An automatic machine (automatic machine) is a self-controlled working machine that performs the whole range of assigned operations. All control functions of the production process, i.e. switching on and off individual mechanisms, changing the order of work of working bodies, are performed by special devices. These devices, without human intervention, can maintain technological processing modes within specified limits.
At the first stage of the development of automation, the task was to automate the execution of individual operations. Interoperational transportation of workpieces and parts, as well as other auxiliary operations were performed manually.
V modern conditions automation tasks have expanded significantly. Now automation covers all stages of the production process, including transport, loading and unloading operations and control of finished parts. In some cases, pipelines with automatic addressing are used.
With the introduction of automated lines, it became necessary to develop fundamentally new product designs that would radically improve the technological methods of their manufacture. The design of the manufactured products must meet the requirements of highly mechanized production.
Thus, the concept of production automation covers a wide range of measures for the development of technological processes for the manufacture of products and the creation of high-performance automatically operating means of production.
The automation process affects not only the technical, but also the social aspects of production, determines fundamental shifts in the economy and organization of production. In our country in last years large automated production facilities for the production of window and door blocks, panel materials and parquet were organized.
Comprehensive mechanization of sawmilling and woodworking processes is associated with the creation of machine systems that combine the performance of various operations of processing, assembly, transportation, and sometimes control of products. Such systems of machines include equipment located in the order of the sequence of operations of the technological process called lines.
Lines of sawmill and woodworking machines, according to the degree of automation, are divided into continuous, semi-automatic and automatic.
A production line is a line of working machines located in the order of a sequence of technological operations and requiring individual maintenance. The machines that make up the production line may or may not be connected by transport devices.
An automatic line is a system of interconnected working machines (machine tools, auxiliary equipment, etc.) located in the course of the technological process and automatically carrying out the assigned sequence of technological operations without the intervention of the worker. Such a system only needs periodic control, adjustment and technical maintenance by the operating personnel. Loading the head machine of the automatic line and receiving finished products are also carried out automatically with the help of special loading and unloading devices.
If some operations of the technological process are not automated and require individual maintenance, the line is called semi-automatic.
The lines may include universal, specialized and special machines. Experience has shown that automatic lines composed of the simplest universal equipment with a low concentration of operations are cumbersome, require a large production area and do not provide the necessary operational reliability.
Composed of automated universal and specialized machines, the lines are more compact and reliable.
When using normalized units and mechanisms (power heads, feeders, unloaders, etc.), the design and construction time of lines is reduced, and costs are reduced.
Lines of sawmill and woodworking equipment can be with rigid, flexible and mixed connection of units. If the machines of the line are interlocked with each other and form a continuous chain with the direct transfer of the workpiece from one position to another, the connection is called rigid. Such a connection is very common in lines, however, in this case, when any of the units stops, the entire line is idle.
Published: March 22, 2012Chapter II
TECHNOLOGICAL PROCESS OF WOODWORKING AND METHODS OF ITS AUTOMATION
Process structure
The technological process of manufacturing wood parts and assembling them into finished products is divided into several parts:
processing of parts and assemblies;
gluing wood;
assembly of units and products;
hydrothermal treatment.
The processing of parts and assemblies is almost always carried out by machine tools, and the assembly of assemblies and products is mainly carried out manually. The gluing of wood in the manufacture of panels or veneering must be accompanied by a certain time delay necessary for the glue to set. Finishing also takes extra time for the applied coatings to dry. At present, mainly the processes of mechanical processing of parts and assemblies made of wood are being automated.
In a machine technological process, a distinction is made between work processes, as well as control and monitoring processes.
Work processes include actions aimed directly at the implementation of a given technological task. The processes of management and control include actions that ensure the correct course of work processes.
The technological process usually consists of a number of separate operations.
It is customary to call an operation a part of a technological process performed at a certain workplace, machine tool or machine unit before proceeding to the processing of the next part. Usually technological process is divided into operations in such a way that the implementation of each of them would solve a certain technological problem, for example, dividing the material but length into a number of blanks, the formation of Oa іпmpі) surfaces, planing to size, the development of thorns, etc.
Operations that are repeated during the processing of each part, that is, with each cycle of the equipment operation, are called cyclic.
Operations are divided into main and auxiliary.
The main ones include operations that directly give technological results, for example, cutting, bending or gluing wood, and auxiliary ones - all other operations necessary to perform this process, for example, loading and unloading, transport, control and management operations.
The time required to perform basic operations on machine tools is called the main technological or machine time. For machines in which the cutting tool or part moves intermittently, the machine time is the sum of the duration of the working stroke of the processing tool or part and the duration of the idle stroke.
Workflows include:
actual working operations, in which the tool directly affects the workpiece being processed;
loading and unloading operations, i.e. loading, installation, direction and fastening of the workpiece before processing and unloading, unclamping and removal of the workpiece after processing;
transport operations, also called transfer operations, in which workpieces or working bodies are mixed from one technological operation to another;
operations of maintenance of the workplace, which are not included in each cycle of equipment operation and are called off-cycle.
Management and control processes include:
work control operations performed to comply with a certain sequence of movement of the workpiece or working bodies, as well as to automatically maintain the established modes (automatic control);
tuning and adjusting (commissioning) control operations performed in advance to adjust the process in accordance with the specified requirements for processing sizes, tolerances, product quality, productivity, etc.;
control operations performed to check the quality, sorting and counting of products, as well as to check the condition and position of the processed workpieces or working bodies.
It is customary to divide the operations of workflows into transitions, passes, installations and positions.
A transition is a part of an operation performed by the same cutting tool when machining the same surface of the object being processed and with a constant mode. If on the machine the same surface of the object is simultaneously processed by several cutting tools, for example, on four-sided planers or tenon-frame machines, this means that several transitions of this operation are performed simultaneously.
A pass is a part of an operation limited to the removal of one layer of material from the same surface of an object and carried out without changing the installation of the working parts of the machine, for example, when planing, grinding the material, planing on a thicknessing machine, etc.
Set-up refers to the part of an operation performed without releasing and re-clamping the workpiece. For example, with a single fastening, two slots are drilled on a grooving machine in one installation, and with two fastening - in two installations.
A position is a part of an operation performed without changing the position of the part relative to the machine, that is, without releasing it from the clamp.
Features of the technology of mechanical processing of wood
Easy workability of wood. The insignificant (compared to metal) resistance of wood to cutting makes it possible to process it with a significant length of contact between the cutting tool and the material and to use high cutting and feed speeds. In this regard, woodworking machines, in comparison with metalworking machines, are distinguished by relatively simple kinematics and very high productivity.
The relatively small efforts required for cutting wood also lead to a simplification of the design of machine tools, including the basing and holding bodies.
Simplicity of shapes and light weight of parts. The majority of wood parts are simple in shape and light in weight. This facilitates the installation, positioning, clamping and feeding of workpieces in the machine and their transfer from one machine to another. Since the automation of machine technological processes often depends on the degree of mechanization transport operations, then this feature of mechanical processing of wood is of particular importance.
Reduced requirements for machining accuracy.
Due to the ability to change its shape and elasticity, the requirements for the precision of mechanical processing of wood are much lower than those of metal. "This facilitates the stabilization of the technological process and simplifies the control and measuring devices.
The predominant distribution of straight-through processing.
In mechanical processing of wood, a through movement of a part past a rotating cutting tool is mainly practiced. This processing scheme was called the checkpoint. It makes it possible to use the simplest design of transport devices and carry out processing simultaneously with several tools, which increases the productivity of the machine.
Thus, in the very methods of processing wood parts, the principle of flow is incorporated, which makes it possible to automate the process by the most simple means.
Big specific gravity auxiliary operations. High processing speeds of wood significantly reduce the duration of the main operations. When auxiliary operations, such as loading and unloading parts on the machine, are not combined with the main ones, their specific weight increases. This prevents a decrease in the total cycle time of processing, i.e., an increase in the productivity of the machine, and thus negates economic effect achieved by reducing the duration of the main operations. Therefore, it is most expedient to combine the main and auxiliary operations in time.
Inhomogeneity of the structure (anisotropy) of wood. Processing wood against the direction of the grain often causes chips, especially when the cutting tool leaves the material being processed, when the natural support of the fibers is less than the cutting force. The uneven structure of the wood also affects the cutting force. This feature of the mechanical processing of wood in some cases necessitates the appropriate regulation of processing modes, for example, when milling. Increasing cutting speeds and improving cutting tools, as well as guides, pressure, feeding and other devices of modern machines can reduce or completely eliminate chips along the wood fibers.
High speed of processing processes. This feature causes increased requirements for the movable working bodies of the machine, especially for the intermittently moving bodies. In some cases, in this regard, it is necessary to use special equipment, which would make it possible to increase the number of inclusions per unit of time.
Key benefits of automated manufacturing
Automation of production increases the productivity of workers and facilitates their work. In addition, it makes it possible to improve working conditions, reduce the duration of the production cycle and the required production space, ensure the rhythm of processes, improve quality and reduce the cost of production.
Increase in labor productivity. Labor productivity of workers in automated production increases as a result of automation of loading blanks and unloading processed parts, joining a number of basic technological operations into a single complex, automation of control, regulation, material transportation, etc.
Due to the concentration of processing typical for automation, the number of working bodies of machines serviced by one worker significantly increases, and his labor productivity increases. Modern automatic machines or systems of machines perform a complex set of operations in a technological process without direct human participation. Thus, automation frees up a significant number of workers. Under capitalism, this leads to an increase in unemployment and a deterioration in the material situation of workers. In a planned socialist economy, an increase in labor productivity as a result of automation is a source of growth in the material well-being of the people and a reduction in the length of the working day. The released labor cadres are used at other enterprises.
In different processes, labor productivity increases unevenly and depends on the degree of concentration of processing and the continuity of the process. The higher the concentration of processing and the greater the degree of continuity of the process, the higher the labor productivity. The highest productivity of workers is achieved when integrated automation production.
Facilitating the work of workers. In automated production, a person only adjusts the automatic system of machines to the desired processing mode, monitors the state of the mechanisms and working bodies of the machine, ensures its loading with blanks and monitors the correct operation of all mechanisms by instruments. Thanks to the automation of production, the labor of the worker approaches that of the engineering and technical personnel.
Improving labor safety. Replacing manual labor with automatically operating machines contributes to a significant increase in labor safety, since the worker observing the progress of the process is located at a distance from the working bodies of automatic machines that directly process the workpieces. In automated production, the protection of the working parts of machines is improved, the noise during their operation is muffled, the collection of wood dust is improved, the harmful effects of heat, moisture, solvents, varnishes, paint, etc. are eliminated. Improving the working conditions of the worker in automated production reduces his fatigue.
Reducing the duration of the production cycle. In serial manual production, periodic launch of batches of blanks is carried out. In this case, the duration of the production cycle is determined mainly by the period of time during which the workpiece lies without movement while waiting for processing.
Automated production is based on in-line methods, in which the workpiece, at the end of one technological operation, is directly transferred to the next. As a result of such an organization of production, all or most of the parts of the product are processed simultaneously, and the production cycle is sharply reduced.
Reducing the duration of the production cycle is accompanied by a significant decrease in the volume of work in progress, which increases the turnover of working capital, and, consequently, improves economic indicators activities of the enterprise.
Reduction of production areas. In well-organized automated production, the reduction in production space is a consequence of the reduction in the duration of the production cycle and the decrease in the volume of work in progress. Eliminates the need for near technological equipment allocate a large area to accommodate work-in-progress parts, so machines can be located closer to one another. The assignment of strictly defined operations to each technological section contributes to the use of multi-operation machines with a high processing concentration, which also makes it possible to restrict ourselves to the smallest production area.
The rhythm of production. The time interval between the exit from the workplace of two consecutive workpieces one after the other is called a rhythm or work cycle. In manual production, the rhythm in different operations is usually not the same, which complicates the planning and organization of such production. In automated manufacturing, the operations of a technological process are usually performed on several machines, the work of which must be carried out synchronously. Synchronicity is most often provided by the equality or multiplicity of the rhythms of the machines participating in the process. The multiplicity of the rhythm greatly facilitates production planning. Rhythmic production requires a particularly clear organization, since any change in the established rhythm disrupts work and can lead to downtime in certain areas.
Improving product quality. Strict observance of the rhythm and mode of operation of machines, reduction of the production cycle, mechanization and automation of control, automatic regulation of modes of machining of parts and units of products, automation of assembly and finishing operations ensure a higher quality of products.
Reducing the cost of production. Automation of technological processes usually leads to a decrease in the cost of production. This is achieved as a result of an increase in the productivity of workers, a reduction in the duration of the production cycle and production: areas, a more rational organization of production.
Conditions for the implementation of complex automation in woodworking
The most important conditions for the implementation of integrated automation in woodworking are: specialization of production, manufacturability of product design, normalization and unification of the dimensions of parts, normalization of allowances, introduction unified system tolerances and landings.
Production specialization. Under specialization, such an organization of production is reduced, in which a steady production of homogeneous products is ensured for a long time.
In specialized production, more favorable conditions are created for the introduction of progressive technology "and technology, since the release of homogeneous products makes it possible to normalize technological processes, to enlarge the size of batches of products launched into production, to apply continuous production methods, etc.
The rational degree of production specialization is determined by technical and economic calculations and does not remain constant. In most cases, the specialization of each woodworking enterprise is determined by the volume of production, which depends on the availability of raw materials and the conditions of sale. The development of transport, the improvement of product designs and the introduction of continuous production methods create conditions for a gradual increase in the degree of specialization in the woodworking industry. In this regard, in furniture production, for example, there are specialized enterprises that produce upholstered furniture, joinery and bent chairs, cabinet furniture. In large economic regions, it is advisable to specialize the production of cabinet furniture, in turn, creating, for example, enterprises for furniture, small-sized, kitchen furniture, etc.
Automation of technological processes is easier to carry out, at enterprises with high degree specializations that produce, for example, any one product: carpentry or bent chair, parquet, skis, tables, etc.
Manufacturability of the product design. The concept of "manufacturability" establishes a link between product design, technology, organization and production economics. Technological design is called such a design that meets the technical requirements and at a given scale of production and adopted technology provides the least cost of funds for the manufacture of products.
With a change in production conditions, the assessment of the manufacturability of the same design also changes. For example, the manufacturability of the same design can change as a result of the introduction of new materials, changes in scale, improvements in equipment and manufacturing organization.
The currently existing designs of the overwhelming majority of products made of wood were created in conditions of poorly mechanized production and for a long time remained largely unchanged. Therefore, in the conditions of automated production, the manufacturability of the design of these products requires revision.
For example, paneled doors with bars connected on dowels are more technologically advanced than doors with bars connected by thorns, since in the manufacture of the first wood consumption is 8-10% less - The most technologically advanced panel doors, especially with the use of wood-based panels, improve the beneficial use of wood and simplify the technological process.
In the production of cabinet furniture, the panel room is considered more technologically advanced, the design of which is based on the progressive principle of mass production of panels and rational methods of their connection.
Often even slight changes in the designs of products that do not degrade their quality, make it possible to significantly simplify the manufacture of such products or to use more productive multi-operational equipment. The manufacturability of the product can be significantly improved by expedient replacement source material... So, many wooden products of complex shape, but of a relatively small size, including turned ones, are already expedient to replace with plastic ones. At the same time, complex operations of milling, turning, grinding and finishing completely disappear and, in addition, the consumption of wood is noticeably reduced. As pressing equipment for the manufacture of plastic parts improves, the dimensions of plastic parts will continuously increase.
Normalization and unification of the sizes of parts. When processing details on universal single-operation machines in manual production, the variety of sizes of parts does not really matter, since the changeover of such machines is very simple and does not require much time. On the other hand, in automated production, the changeover of interconnected machines, often of a relatively complex device, is time-consuming and therefore highly undesirable. Therefore, the number of sizes of workpieces must be minimized, if possible, by their normalization and unification.
Normalization is the development of a normal range of preferred sizes, which makes it possible to significantly reduce the number of sizes of parts. When normalizing parts, reducing their number is achieved by combining several parts with the same dimensions into one group, that is, by unifying the dimensions.
Unification is the reduction of several parts to the same size.
Normalization and unification can be carried out in one, two or three sizes of parts, for example, in thickness, length and section. For automated production, it is most important that the processed parts have uniform cross-sections.
Allowance normalization. The size of the machining allowance, that is, the difference between the dimensions of the workpiece and the processed part, usually depends on the dimensions of the parts and must be justified by technical and economic considerations. For some types of products, for example, for sawn timber, processing allowances are regulated by GOST. In woodworking enterprises, processing allowances are usually not regulated by anything and are set arbitrarily. The variety of allowances makes it difficult to process parts in automated production, since workpieces with different allowances have to be processed in different modes.
Normalization of processing allowances is understood as the development of a strictly justified number of allowances to save wood and ensure the stability of processing modes.
Implementation of a system of tolerances and landings. Modern methods of assembling products in assembly devices, on a conveyor or in special assembly machines cause increased requirements for the accuracy of manufacturing parts.
The accuracy of the parts should ensure their assembly into units and products without individual adjustment. For this, the mating dimensions of the parts must be maintained within the established deviations, regulated by the tolerances. When machining according to tolerances, which are assigned according to the required fit of the mating parts, full or partial interchangeability of parts is ensured, and therefore, extensive mechanization and automation of technological processes and high quality products.
Since 1954, uniform standards for tolerances and fit have been established (GOST 6449 - 53). The introduction of this GOST in the woodworking industry is one of the most important conditions for the implementation of complex automation.
Accuracy classes and the type of interchangeability should be selected for each specific case on the basis of technical and economic calculations.
Selection of objects and degree of automation
Automation object. In modern conditions, it is necessary to take into account not only the possibility of automation, but also its economic efficiency, which primarily depends on the correct choice of the automation object.
The most effective is the integrated automation of structurally stable products manufactured in mass quantities. When the share of wages in the cost of the product is small, the efficiency achieved as a result of automation is negligible. Efficiency increases with the automation of the production of labor-intensive products, in the cost of which the production wage has a large specific gravity.
The most suitable objects of automation can be considered matches, pencils, spools, spools, shuttles, chairs, skis, as well as cases of ready-made items, sewing machines, watches, etc., i.e., products of a fairly stable design, produced in mass quantities.
The degree of automation. The degree or level of automation of a process is called an indicator that characterizes the degree of release of a worker from direct participation in the implementation of this process. Quantitatively, the indicator of the level of automation can be expressed as a quotient of dividing the number of automated operations (or their labor intensity) by their total number (or by the total labor intensity):
One of the disadvantages of assessing the indicator of the level of automation through labor intensity is the lack of taking into account the intensity of the process. The main criteria for the expediency of the degree of automation of production are the improvement of working conditions, economic efficiency and the reliability of automatic equipment.
The feasibility of the degree of automation of production primarily depends on its scale. On the large enterprises, producing products in mass quantities, where continuous-winding methods can be applied and jxxt.trw> .; i. sti, there are the most favorable conditions for effective complex automation of technological processes.
If the scale of production limits what is possible and, the manufacture of all parts of the product by continuous-flow methods, complex automation can be carried out in conditions of variable-flow production. However, automated variable-flow production is less efficient, since when changing from one flow to another, a long-term changeover of equipment is usually required. Therefore, in variable-line production, it is necessary to use equipment that does not require significant time for non-re-adjustment.
In small enterprises that produce several types of products, for example, furniture sets, sets of building parts, etc., complex automation of technological processes is associated with significant difficulties and is ineffective. At such enterprises, most often they strive to carry out complex mechanization and partial automation, which extends to individual sections of the technological process or only to its individual operations.
Automation of a separate operation is reduced to the automation of the machine cycle and is called small automation... It can be carried out at any scale of production.
Classification of automation systems
Automation of technological processes is carried out with the help of automatic devices, that is, mechanisms and apparatus that free a person from the control of the processes being performed. Depending on the purpose, automatic devices are classified as various systems automation.
For the automation of technological processes, the following systems(Fig. 1): automatic control of the technological process operations necessary to obtain the final result; automatic regulation of the course of the technological process when external or other conditions change; automatic control over the course of the technological process.
Automatic control systems. These systems carry out the change of technological operations or their component parts according to a predetermined plan, regardless of changes in external or other conditions and on the course of the technological process.
Characteristic feature automatic control systems is the presence of a stable program of change of operations, as well as the lack of means for measuring the parameters of the technological process, since the latter do not affect the operation of the systems.
The operation of the elements of automatic control systems is reliable. If any element fails, the process is usually interrupted.
Depending on the nature of the process, automatic control is divided into simple (cyclic) and software.
Automatic control of machines that repeat the same operations with the object being processed, that is, those machines whose work consists of identical cycles following one after the other, is called simple. This group includes most of the cycle woodworking machines.
Automatic control is called software control, which provides for a predetermined change in individual operations of a technological process, which cannot be divided into identical cycles.
Earlier to program management included machine control systems, the movement of the working bodies of which could change from cycle to cycle, for example, by printing machines, weaving machines, etc. Lately the program control also includes systems that provide a quick change in the program of machine tools when processing from one part to another.
Automatic control systems. These systems qualitatively change the course of the technological process according to a strictly defined law or keep a certain process parameter constant.
Automatic control systems measure the value of the controlled parameter and automatically influence the technological process in such a way as to maintain the required value of this parameter.
Failure of any control element usually does not interrupt the process, but affects its result.
Automatic regulation can be continuous, programmed and tracking.
Regulation of a constant parameter (stabilization) is the automatic maintenance of the constancy of any one technological parameter, for example, temperature, voltage, power, speed, pressure, speed, etc. Regulation of a constant parameter is, in particular, automatic maintenance set temperature in the drying chamber.
The control of a parameter in time according to a certain law, for example, a predetermined change in temperature in a drying chamber, belongs to the program.
The follow-up regulation of the parameter is similar to the program regulation, but it is performed not according to a program preset in time, but depending on the value of another parameter, that is, according to a program in time, previously unknown. The following can be attributed, in particular, to the automatic regulation of the temperature in the drying chamber, depending on the moisture content of the wood.
Automatic control systems. For automatic control of process parameters, automatic safety devices and devices are used to register the value of the controlled parameter. In many cases, the functions of automatic control of process parameters and their regulation are combined in one device - an automatic regulator. In this case, the control device is included in the regulator.
Product quality control is carried out using various means, which, if necessary, also allow sorting products in finished form (passive control) or in the process of their manufacture (active control). Accounting for manufactured products is carried out using various kinds of counters, often attached directly to the machine.
Control over the operation of equipment is usually carried out using instrumentation, which is attached directly to the equipment or installed on special control panels.
The main methods of automation of the technological process
As already noted, there are two main methods of automation: the first is the automation of existing processes based on the use of existing equipment through its modernization, and the second is the creation of new automatic equipment based on a radical improvement of technological processes.
Equipment modernization. Such automation does not change the technological process and is reduced to the modernization of non-automatic machines and to their integration into a single automatic system. Automation means, in this case, supplement the existing basic equipment and cannot be used in the most rational way.
In woodworking, the first automatic and semi-automatic lines based on the use of conventional universal equipment were organized in Vitebsk and Kiev furniture factories, The Kiev woodworking plant, at the Moscow furniture and assembly plant No. 2 and at other enterprises.
The important advantages of this automation are significant cost savings and availability in almost any enterprise. In most cases, the cost of automation by upgrading existing equipment is 4-5 times less than the cost of replacing existing equipment with a new, automatic one.
Since, as a result of the modernization, universal equipment with a relatively low concentration of operations is retained, production facilities are used worse than in the case of using special multi-stage equipment.
When automating individual operations on modernized machines, loading and unloading of the machine is automated. With the automation of a site or complex automation of the entire production, inter-operational transport, management, control and regulation are also automated.
On many universal woodworking machines: with mechanized material feeding, the work cycle is automated. These machines include: autofuging, thicknessing, four-sided planers, some circular saws, double-sided tenoning, three-cylinder grinding, etc. Automation of these machines comes down to equipping them with automatic loading and unloading devices. When such machines are included in an automatic line, it is necessary that their performance is the same and that the inter-operational transport devices act synchronously with the loading and unloading devices.
Introduction of new automatic equipment. Technological processes change according to the level of development, science and technology. Currently, the most characteristic two principles of building a technological process - differentiation and concentration of processing.
Differentiation is the division of the process of processing parts into a number of simple operations for each of them to be performed with one tool sequentially on one or on different machines.
Differentiation makes it possible to use for each operation separate, simple, narrow-operating machines, and, therefore, to quickly create and master new equipment, which is especially important in the mechanization of technological processes. However, the dismemberment of the processing process leads to an increase in production areas and service personnel. In addition, the processing of parts on many machines reduces the accuracy of their manufacture and increases the labor intensity.
For the period of automation of technological processes, the principle of concentration of processing is characteristic, corresponding to a higher level of development of science and technology.
Concentration is understood as the simultaneous (parallel) processing of one or more parts with many tools.
The widespread introduction of concentration into processing became possible as a result of the emergence of an individual electric drive, the improvement of pneumatic and hydraulic drives and the development of reliably operating means of automatic control of machine tools.
The concentration of processing makes it possible to significantly reduce the production area, increase the productivity of the worker and increase the removal of products from one square meter of the production area.
The introduction of new automatic, mainly multi-operational equipment is possible on the basis of a radical improvement of technological processes. In turn, automation stimulates further improvement of production technology and the most efficient use of modern means automation.
A characteristic feature of the development of modern industrial production with the mass production of homogeneous products is the widespread introduction of multi-operation (modular) specialized machines instead of universal single-operation general-purpose machines. The former are distinguished by significantly higher productivity and occupy less production area.
The need for modular machines for serial production is still relatively small, and, consequently, the cost of manufacturing such machines is ten times higher than the cost of serial ones. Therefore, the use of specialized machine tools should be justified in each individual case by technical and economic calculations. Reducing the cost of specialized machine tools can be achieved by introducing normalized aggregate units. However, at present, rational forms of aggregation of woodworking machines have not yet been found.
In preparation for the automation of production processes on the basis of the introduction of new equipment, two main tasks are solved: the design of automatic machines and the design of automatic lines.
When designing new automatic machines, they usually strive to automate the entire cycle of work, including loading blanks and unloading parts. Such machines are suitable for both individual work and for integration into automatic lines.
When designing automatic lines from specialized automatic equipment, the possibilities for choosing the best option are much greater than when assembling lines from universal equipment.
excerpts from the book Automation of technological processes in woodworking, N. V. MAKOVSKY (attention! Recognition errors are possible)
From: LidiaZaiceva, & nbsp58588 views
CHAPTER X MECHANIZATION AND AUTOMATION OF WOODWORKING PRODUCTIONS
MACHINE LINES
The seven-year plan for the development of the national economy of the Soviet Union provides for extensive mechanization and automation of woodworking industries. Mechanization and automation open up great opportunities for improving the quality and increasing output, reducing its cost, increasing labor productivity, and improving working conditions.
Mechanization and automation of production processes is the basis for the creation of a continuous line production in the woodworking industry. Flow methods of organizing the production process contribute to the growth and improvement of production based on higher technology.
In-line semi-automatic and automatic lines are being introduced both in individual technological areas and in factories as a whole. In the latter case, we are already talking about the creation of automatic factories.
Automatic lines consist of machine tools or automatic machines that perform processing and control operations; devices for loading and unloading the line and transporting parts from one machine to another without intervention from the worker; devices serving to fix (fix) parts during their processing, and a single line control system.
The line is served by one operator located at the central control panel. If the loading of blanks and unloading of products, as well as intermediate control and rejection of them are performed by workers, then in this case the line is called semi-automatic.
The automation of woodworking technological processes is currently developing in three directions. Automatic lines are created either on the basis of existing universal general-purpose machines with their partial reconstruction, or on the basis of new specially designed specialized stacks, or on the basis of universal general-use machines and new specialized machines (combined completing).
One of the factors that determines the productivity of automatic lines is the design feed rate. To maximize the use of the lines, it is important to eliminate the loss of time associated with loading the bunker, harvesting products, transporting material, as well as eliminating downtime associated with changing the cutting tool, adjusting the line, lubricating, checking the state of critical units, etc.
The productivity of automatic lines is much higher than that of conventional production lines. The number of service workers is reduced, the area under the machines is reduced. Work on automatic lines Safe and less tiring, it comes down to observing the machines and controlling the line, placing the workpieces in the loading devices at the beginning of the line and removing the finished products at the end of the line. Odzako, the automation of processes in the presence of complex automatic equipment requires a higher qualification of workers for its maintenance and a good knowledge of many designs of woodworking machines.
The production of finished products from wood today can be substantially mechanized. The whole process of wood processing is characterized by varying degrees of complexity, which depends on the size of the finished product and its configuration. The production of wood products consists of a series of sequential operations.
The procedure for carrying out the technological process of production
The very first stage before direct production is the preparation of raw materials, which consists in drying the wood.
Drying can be carried out both naturally, when wood is stacked, and in a special drying chamber. The advantage of the latter method is a significant reduction in the process of imparting the required percentage of moisture to the wood.
A drying chamber for wood is a rather complex mechanism, consisting of several pieces of equipment, each of which performs a specific function.
Typical composition drying chamber:
- fencing;
- thermal equipment;
- circulation system;
- air exchange system;
- humidification system;
- control systems for the drying process and automation.
The drying process, as a rule, includes the following technological operations:
- initial heating of wood,
- control over the mode of drying and moisture content of wood,
- moisture and heat treatment,
- air conditioning and cooling.
The drying mode is selected based on the current moisture content of the wood, the size of the workpieces.
It can be done before or after the drying of the raw wood.
Saw frames, circular saws or band saws are used for cutting.
Woodworking Equipment - Saw Frame
Depending on the tasks set, sawmill frames can differ in:
- type of cut (vertical and horizontal);
- number of storeys (one-story and two-story);
- single-rod and double-rod,
- mobility (stationary and mobile);
- power (large, small);
- speeds (high-speed and low-speed)
- purpose (ordinary and special).
Horizontal are used in cases when it is necessary to cut logs of hardwood for the production of plywood.
Two-storey ones are distinguished by high productivity. In them, parts of a powerful drive are located in the lower floor of the building, the working parts of the machine. including parcel rollers - on the top floor.
Typical composition of a sawmill frame:
- bed;
- cutting mechanism;
- feed mechanism;
- governing bodies;
- Lubrication system;
- protection device.
One of important characteristics cutting mechanism is skylight... This is the distance between the vertical posts of the saw frame. The most common clearance sizes are from 500 to 1000 mm. The clearance determines the maximum thickness of the log that can be cut.
The lumen of the sawmill frame is chosen according to the characteristic specification of the raw material to be cut. It is necessary to choose the clearance based on the thickness of the logs that have a sufficient specific gravity in the total composition. Single logs with the maximum thickness are not taken into account, since excessive dimensions of the clearance cause a decrease in the performance of the frame.
The largest number of saws that can be installed in the frame depends on the size of the clearance. This indicator is indicated in the equipment passport and usually amounts to:
- for powerful frames - 12-20;
- for special - up to 40;
- for low-power ones - 6-10.
Woodworking band saw LT40
The main parameter of the band saw is the saw pulley diameter (1.1 - 3 m).
The larger the diameter of the pulley, the wider and thicker the saw, and therefore the saw is more stable and can cut at a higher feed rate. In addition, machines with a large pulley diameter can cut large diameter logs. In this case, the pulleys should be located as close to each other as possible to reduce vibrations. working area saws.
Machine types differ in material feed rate.
Small feed machine performance:
- saw pulley diameter: 1.1 - 2.4 m;
- saw thickness: 1.2 - 2.2 mm;
- saw width: 120 - 300 mm;
- the actual feed speed for soft rocks: 10 - 50 m / min, for hard rocks 5 - 25 m / min.
Indicators of the large feed machine:
- saw pulley diameter: 1.5 - 3.0 m;
- saw thickness: 1.6 - 2.6 mm;
- saw width: 150 - 450 mm;
- actual feed speed for soft rocks: 40 - 150 m / min, for hard rocks 20 - 75 m / min.
It should be noted that with an increase in the feed rate, the kerf width increases, the dimensional accuracy of the workpieces decreases, which requires additional processing and increases the consumption of electricity.
Small power circular saw for wood
Circular saws with a diameter of up to 1.5 meters are used in industry, which allow sawing wood with a diameter of up to 0.6 m. The productivity of such machines allows sawing up to 25 cubic meters of raw materials with a diameter of 25 cm per hour with wood loss from 1.5 to 4%.
Then the so-called rough blanks are made, which are segments of a certain size. They are machined in two stages. At the first of them, the workpiece is processed from all sides and then it is trimmed in order to give the future product the required dimensions and the desired geometric shape. As a result of such processing, a finishing workpiece is obtained.
Miter saw TS-2 for wood
The next stage involves the formation of the finished product, which consists of grinding, drilling and some other methods of processing the finished product. These two processing stages use solid wood blanks. All components of the finished product are veneered or glued before final processing.
Typical Woodworking Grinding Machine
The final stage of production is the assembly of the finished product, which also includes several stages. First, all the parts are assembled into separate components, then the dimensional accuracy is checked. The very last stage is the general and final assembly of the finished product. It can be finished before or after final assembly.
Woodworking technology, processes
In the process of manufacturing wooden parts, it is very important to monitor their interfacing with each other during assembly. The presence of such a parameter as fit determines the density, strength and movement of parts relative to each other.
Today there are several types of landings:
- tense;
- press;
- sliding;
- chassis;
- easy-moving;
- dense.
When mating the surfaces of parts, the tolerance of straightness and flatness must correspond to 10-12 degrees of accuracy according to GOST 6449.3-82 with a length of parts of 1-1.6 m. Non-mating surfaces must correspond to 13-15 degrees of accuracy.
Differentiation is very important in woodworking. It is the division of all operations into smaller, separate independent operations, thereby increasing labor productivity.
In small enterprises, the entire process of assembling parts can be performed by one worker or a whole team, which will be considered one operation. The ability to entrust him with the assembly of more complex parts and finished products directly depends on the qualifications of the worker. Production can be both mass and individual, and in each of them it is necessary to perform the division of operations, equipment and fixtures.
One of critical factors that directly affect the quality of the finished product is the proper fixation of the workpiece on the woodworking machine. The biggest challenge is fixing the part before drilling the holes, as this requires maximum fixing precision.
Typical drilling machines
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