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Woodworking machinery

Mechanization and automation of production

Under the mechanization of technological processes understand the partial replacement of manual labor by a machine. Human participation is necessary here to load and unload parts, control their accuracy and quality of processing.

Under the automation of technological processes is understood the control of individual machines or a group of machines and control over them, excluding the direct participation of a person in this. Automatic machine or the line work according to a program that was pre-compiled and debugged by a person. The use of automation in the woodworking industry improves the quality of products and labor productivity, and also significantly improves the working conditions of workers.

AT furniture production, despite the large range of products, mass production of parts from sheet and panel materials is being created with the widespread use of semi-automatic machines, automatic machines and automatic lines.

Semi-automatic machines are machines that operate in an automatic cycle, the repetition of which requires the intervention of a worker. Usually, on semi-automatic machines, the worker manually sets, fixes and detaches the workpiece, turns on the feed to carry out the work cycle.

Automatic machines are machines on which parts are made without the direct participation of the worker. The operator only periodically loads stores or feeders, measures and controls the machined parts, adjusts the machine as it is misaligned.

Automatic line - a set of main, auxiliary, transport equipment and mechanisms that provide automatic basing, fixing, rotation and movement of workpieces in order to perform technological operations in the required sequence and at a given rhythm without the direct participation of a person. The functions of the worker are to control the operation of the equipment and its timely adjustment, as well as to ensure uninterrupted loading of workpieces at the beginning of the line and unloading of finished parts at its end.

At integrated automation in one continuous technological process, various technological operations are combined (for example, cutting, veneering, trimming, grinding).

Several automatic lines of sequential or parallel action can be combined into a single automatic system. Such systems of automatic lines are called automatic sections. If the main production processes are carried out on automatic lines, then their combination forms an automatic workshop or plant.

The automation of production qualitatively changes the content of the worker's labor actions. These actions consist in setting up and setting up equipment, performing minor repairs and testing equipment, monitoring the progress of the production process, controlling the quality of processing finished products, etc. The degree of efficiency in using expensive equipment depends on the skill and qualifications of the worker performing these functions.

The basis for further technical progress in the sawmill and woodworking industry is mechanization and automation production processes aimed at solving one of important tasks- replacement of manual labor by the work of mechanisms and machines.

Mechanization is the replacement of manual labor by machines. In this case, the machine performs the work that was previously performed by a person with the help of muscle power.

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 used.

The working machine (non-automated) has, as a rule, the mechanisms of working moves and performs mainly the main working movements. Auxiliary operations, such as loading blanks, 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 physical labor, but also from the duties of 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 basic and auxiliary operations production process. The performance of such a machine is not related to the physical capabilities of a person, so it can reach a high level.

An automatic machine (machine) is a self-controlled working machine that performs the entire range of assigned operations. All the functions of managing the production process, i.e. turning on and off individual mechanisms, changing the order of operation of the working bodies, are performed by special devices. These devices without human intervention can maintain technological processing modes within the specified limits.

At the first stage of development of automation, the task was to automate the execution of individual operations. Interoperational transportation of blanks and parts, as well as other auxiliary operations, were performed manually.

AT modern conditions automation tasks have expanded significantly. Now automation covers all parts 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 designs of products, which would make it possible to radically improve the technological methods of their manufacture. The design of 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 technical, but also social aspects production, determines fundamental shifts in the economy and organization of production. In our country in last years organized large automated production for the production of window and door blocks, plate materials and parquet.

The complex 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 machine systems include equipment arranged in the order of the sequence of operations of the technological process and are called lines.

Lines of sawmills and woodworking machines are divided into flow, semi-automatic and automatic according to the degree of automation.

A line is called a line of working machines arranged in the order of the sequence of technological operations and requiring individual maintenance. The machines that are part of the production line may or may not be connected by transport devices.

An automatic line is a system of interconnected working machines (machines, auxiliary equipment etc.), located along the technological process and automatically carrying out the assigned sequence of technological operations without the intervention of the worker. Such a system needs only periodic monitoring, adjustment and maintenance from the side service 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.

Lines can 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 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 time for designing and creating lines is reduced, and costs are reduced.

Lines of sawmill and woodworking equipment can be with rigid, flexible and mixed connection of aggregates. 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, but in this case, when any of the units stops, the entire line is idle.

The production of finished wood products today can be significantly 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 order of the technological process of production

The very first stage before production itself is the preparation of raw materials, which consists in drying the wood.

Drying can be carried out both in a natural way, when the wood is stacked, and in a special drying chamber. The advantage of the latter method is a significant reduction in the process of giving the wood the desired percentage of moisture.

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 of the drying chamber:

- fencing;

— thermal equipment;

— circulation system;

— air exchange system;

- humidification system;

– drying process control systems and automation.

The drying process, as a rule, includes the following technological operations:

- initial heating of wood,

– control over the mode of drying and wood moisture,

– moisture and heat treatment,

- air conditioning and refrigeration.

The drying mode is selected based on the current moisture content of the wood, the size of the blanks.

It can be performed before or after drying the raw wood.

For cutting, sawmill frames, circular saws or band saws are used.

Woodworking equipment - sawmill frame

Depending on the tasks, sawmill frames can vary in:

- type of cut (vertical and horizontal);

- number of floors (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 where it is necessary to cut logs of hard rocks for the production of plywood.

Two-story high-performance. In them, parts of a powerful drive are located on the lower floor of the building, the working parts of the machine. including parcel rollers - on the top floor.

Typical sawmill frame composition:

- bed;

- cutting mechanism;

- feed mechanism;

— governing bodies;

- Lubrication system;

- protection device.

One of the important characteristics of the cutting mechanism is clearance. This is the distance between the vertical posts of the saw frame. The most common gap sizes are from 500 to 1000 mm. Clearance determines the maximum thickness of a log that can be sawn.

The clearance of the saw frame is chosen according to the characteristic specification of the raw material planned for sawing. It is necessary to choose a clearance based on the thickness of logs that have sufficient specific gravity in the general composition. Single logs with a maximum thickness are not taken into account, since excessive clearance dimensions cause a decrease in frame performance.

The maximum number of saws that can be installed in the frame depends on the size of the clearance. This indicator is indicated in the passport for equipment and, as a rule, is:

- for powerful frames - 12-20;

- for special - up to 40;

- for low-powered - 6-10.

Band saw woodworking machine LT40

The main parameter of the band saw is the diameter of the saw pulley (1.1 - 3 m).

The larger the pulley diameter, the greater the width and thickness of 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 logs of large diameters. In this case, the pulleys should be located as close as possible to each other to reduce the oscillations of the working area of ​​​​the saw.

Machine types differ in material feed speed.

Small feed machine parameters:

- diameter of the saw pulley: 1.1 - 2.4 m;

- saw blade thickness: 1.2 - 2.2 mm;

– saw width: 120 – 300 mm;

— actual feed rate for soft rocks: 10 – 50 m/min, for hard rocks 5 – 25 m/min.

Large feed machine parameters:

– saw pulley diameter: 1.5 – 3.0 m;

- saw blade thickness: 1.6 - 2.6 mm;

– saw width: 150 – 450 mm;

- actual feed rate 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 width of the cut increases, the accuracy of the dimensions of the workpieces decreases, which requires their additional processing and the consumption of electricity increases.

Small wood circular saw

In industry, circular saws with a diameter of up to 1.5 meters are used, 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 draft 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 fine workpiece is obtained.

Trimming machine TS-2 for wood

The next stage involves the formation of the finished product, which consists in grinding, drilling and some other methods of processing the finished product. In these two stages of processing, solid wood blanks are used. All components of the finished product are lined or glued before final processing.

Typical sanding woodworking machine

The final stage of production is the assembly of the finished product, which also includes several stages. First, all 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 wood parts, it is very important to monitor their pairing 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-going;

- dense.

When mating the surfaces of parts, the tolerance of straightness and flatness must correspond to 10-12 degrees of accuracy in accordance with GOST 6449.3-82 with a length of parts of 1-1.6 m. Non-conjugated surfaces must correspond to 13-15 degrees of accuracy.

A very important factor in woodworking is differentiation. It represents 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 as one operation. The ability to entrust him with the assembly of more complex parts and finished products directly depends on the qualification of the worker. Production can be both mass and single, and in each of them it is necessary to carry out the division of operations, equipment and fixtures.

One of critical factors directly affecting the quality of the finished product is the proper fixation of the workpiece on the woodworking machine. The biggest difficulty is fixing the part before drilling holes, since maximum fixation accuracy is required here.

Typical drilling machines

Published: March 22, 2012

Chapter II

TECHNOLOGICAL PROCESS OF WOODWORKING AND METHODS OF ITS AUTOMATION

Process structure

The technological process of manufacturing parts from wood and assembling them into finished products is divided into several parts:

processing of parts and assemblies;

gluing wood;

assembly of components and products;

hydrothermal treatment.

The processing of parts and assemblies is almost always performed by machine tools, and the assembly of assemblies and products is mainly carried out manually. Gluing wood in the manufacture of panels or veneering must be accompanied by a certain exposure in time, necessary for the adhesive to set. Finishing also requires additional time for the applied coatings to dry. Processes are currently being automated machining details and knots from wood.

In the machine process, work processes are distinguished, as well as management and control processes.

Work processes include actions aimed directly at the implementation of a given technological task. Management and control processes include actions that ensure the correct flow of work processes.

The technological process usually consists of a number of separate operations.

It is customary to call an operation a part of the technological process performed at a specific workplace, machine or machine unit before moving on to the processing of the next part. Usually, the technological process is divided into operations in such a way that the execution of each of them would solve a certain technological problem, for example, the separation of the material along the length into a number of blanks, the formation of a surface, planing to size, making spikes, etc.

Operations that are repeated during the processing of each part, i.e., at each cycle of equipment operation, are called cyclic.

Operations are divided into main and auxiliary.

The main ones include operations that directly give technological results, such as cutting, bending or gluing wood, and the auxiliary ones include all other operations necessary to complete this process, such as loading and unloading, transport, control and management operations.

The time required to perform the basic operations on the machines 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 working body or part and the duration idle move.

Workflows include:

actual working operations, in which the tool directly affects the workpiece;

loading and unloading operations, i.e. loading, installing, guiding and securing the workpiece before processing and unloading, unfastening and removing the workpiece after processing;

transport operations, also called transfer operations, in which workpieces or working bodies are moved from one technological operation to another;

workplace maintenance operations that are not part of each cycle of equipment operation and are called off-cycle.

Management and control processes include:

working 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);

adjustment and adjustment (adjustment) control operations performed in advance to set up 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.

Workflow operations are usually divided into transitions, passes, settings and positions.

A transition is a part of an operation performed by the same cutting tool when processing the same surface of the object being machined and with the same mode. If on the machine the same surface of an object is simultaneously processed by several cutting tools, for example, on four-sided planers or tenoning-frame machines, this means that several transitions of this operation are performed simultaneously.

A pass is a part of the operation, limited to the removal of one layer of material from the same surface of the object and carried out without changing the installation of the working bodies of the machine, for example, when planing, grinding material, planing on thicknesser etc.

Installation is the part of the operation that is performed without releasing and re-securing the workpiece. For example, with a single fixing, two sockets are drilled on a drilling and grooving machine in one setting, and with a double fixing, in two settings.

The position is the part of the 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. Insignificant (compared to metal) resistance of wood to cutting makes it possible to process it with a significant length of contact cutting tool material and apply high cutting and feed speeds. In this regard, woodworking machines, compared with metalworking machines, are characterized by relatively simple kinematics and very high productivity.

The relatively small forces required for cutting wood also lead to a simplification of the design of machine tools, including locating and holding bodies.

Simplicity of forms and low weight of parts. The prevailing part of the parts made of wood is characterized by simplicity of form and low weight. This facilitates the installation, basing, fixing and feeding of workpieces in the machine and their movement from one machine to another. Since the automation of machine technological processes often depends on the degree of mechanization of transport operations, this feature of the mechanical processing of wood is of particular importance.

Reduced requirements for processing accuracy.

Due to the ability to change its shape and elasticity, the requirements for the accuracy of mechanical processing of wood are much lower than those of metal. "This facilitates the stabilization of the technological process and simplifies control and measuring devices.

The predominant distribution of pass-through processing.

In the mechanical processing of wood, the through movement of the part past the rotating cutting tool is mainly practiced. Such a processing scheme is called a pass-through. It makes it possible to use the simplest design of transport devices and process simultaneously with several tools, which increases the productivity of the machine.

Thus, the principle of threading is laid down in the methods of processing wood parts, which makes it possible to automate the process by the simplest means.

Large share of auxiliary operations. High wood processing speeds 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 share increases. This prevents a reduction in the overall cycle time, i.e., an increase in machine productivity, and thus negates economical effect, achieved as a result of reducing the duration of the main operations. Therefore, it is most expedient to combine the main and auxiliary operations in time.

Structure heterogeneity (anisotropy) of wood. Processing wood against the direction of the fibers often causes chipping, especially when the cutting tool exits the material being processed, when the natural support of the fibers is less than the cutting force. The heterogeneity of the wood structure is also reflected in the cutting force. This feature of the mechanical processing of wood in some cases necessitates the appropriate regulation of processing modes, for example, during milling. The increase in cutting speeds and the improvement of the cutting tool, as well as the guides, clamps, feeders and other devices of modern machine tools make it possible to reduce or completely eliminate chips along the wood fibers.

High speed processing processes. This feature causes increased requirements for the movable working bodies of the machine, especially for intermittently moving bodies. In a number of cases, in connection with this, it is necessary to use special equipment that would make it possible to increase the number of inclusions per unit time.

The main advantages of automated production

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 production cycle and the necessary production areas, ensure the rhythm of processes, improve quality and reduce the cost of production.

Increasing labor productivity. Labor productivity of workers on automated production increases as a result of automation of loading blanks and unloading of machined parts, connection into a single complex of a number of basic technological operations, automation of control, regulation, material transportation, etc.

Due to the concentration of processing characteristic of automation, the number of working bodies of machines serviced by one worker increases significantly, and the productivity of his labor increases. Modern automatic machines or machine systems perform complex complex operations of the technological process without the direct participation of a person. 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. Under the conditions of 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 workers are used in other enterprises.

In different processes, labor productivity increases differently 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 productivity. The highest labor productivity of workers is achieved with complex automation of production.

Facilitate the work of workers. In automated production, a person only adjusts the automatic system of machines to the desired processing mode, monitors the condition of the mechanisms and working parts of the machine, ensures its loading with blanks and monitors the correct operation of all mechanisms using instruments. Thanks to the automation of production, the labor of a worker approaches the labor of engineering and technical personnel.

Improving labor safety. The replacement of manual labor by automatically operating machines contributes to a significant increase in labor safety, since the worker who monitors the progress of the process is at a distance from the working bodies of automatic machines that directly process workpieces. In automated production, the protection of the working bodies of machines is improved, the noise during their operation is muffled, the capture of wood dust is improved, and bad influence heat, humidity, solvents, varnishes, paints, etc. Improving the working conditions of a worker in automated production reduces his fatigue.

Reducing the duration of the production cycle. In serial non-automated production, batches of blanks are periodically launched. The duration of the production cycle in this case is determined mainly by the period of time during which the workpiece lies without movement in anticipation of processing.

Automated production is based on flow methods, in which the workpiece at the end of one technological operation is directly transferred to the next. As a result of this organization of production, all or most parts of the product are processed simultaneously, and the production cycle is drastically 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 working capital and therefore improves economic indicators enterprise activities.

Reducing production space. In well-organized automated production, the reduction in production space is a consequence of a reduction in the duration of the production cycle and a decrease in the volume of work in progress. Eliminates the need for technological equipment allocate large area to accommodate work-in-progress parts, so machines can be placed closer to each other. Assigning strictly defined operations to each technological section promotes the use of multi-operational machines with a high concentration of processing, which also makes it possible to limit oneself to the smallest production area.

rhythm of production. The time interval between the exit from the workplace of two workpieces following one after the other is called the rhythm or work cycle. In non-automated production, the rhythm in various operations is usually not the same, which makes it difficult to plan and organize such production. In automated manufacturing, workflow operations are usually performed on several machines, which must be performed synchronously. Synchronicity is most often ensured by the equality or multiplicity of the rhythms of the machines involved 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 the modes of machining 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 reduction in the cost of manufactured products. This is achieved as a result of increasing the productivity of workers, reducing the duration of the production cycle and production: areas, more rational organization of production.

Conditions for the introduction of integrated automation in woodworking

The most important conditions for the introduction of integrated automation in woodworking are: specialization of production, manufacturability of product design, normalization and unification of the dimensions of parts, normalization of allowances, the introduction of a unified system of tolerances and fits.

Production specialization. Under specialization, such an organization of production decreases, which ensures the stable production of homogeneous products for a long time.

In specialized production, more favorable conditions are created for the introduction of advanced technology "and technology, since the production of homogeneous products makes it possible to normalize technological processes, enlarge the size of batches of products launched into production, apply in-line production methods, etc.

The rational degree of specialization of production 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 marketing conditions. The development of transport, the improvement of product designs and the introduction of in-line production methods create conditions for a gradual increase in the degree of specialization in the woodworking industry. In this regard, in the furniture industry, for example, there are specialized enterprises that produce upholstered furniture, carpentry and curved chairs, cabinet furniture. In large economic regions, it is advisable to specialize the production of cabinet furniture, creating, for example, enterprises of furniture, small-sized, kitchen furniture, etc.

Automation of technological processes is easier to implement, in enterprises with high degree specializations, producing, for example, any one product: carpentry or bent chair, parquet, skis, tables, etc.

Manufacturability of the product design. The concept of "manufacturability" establishes a relationship between product design, technology, organization and economics of production. A technological design is a design that satisfies technical requirements and for a given scale of production and the adopted technology provides the lowest 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 may change as a result of the introduction of new materials, changes in scale, improvements in equipment and organization of production.

The currently existing designs of the vast majority of products made from wood were created under conditions of poorly mechanized production and remained basically unchanged for a long time. Therefore, in conditions of automated production, the manufacturability of the design of these products requires revision.

For example, panel doors with bars connected on dowels are more technologically advanced than doors with bars connected with spikes, since in the manufacture of the former, wood consumption is 8-10% less. improve the useful use of wood and simplify the technological process.

In the production of cabinet furniture, panel furniture is considered more technologically advanced, the design of which is based on the progressive principle of mass production of shields and rational methods of their connection.

Often, even small changes in the design of products that do not impair their quality make it possible to significantly simplify the manufacture of such products or use more productive multi-operational equipment. The manufacturability of the product can be significantly improved by expedient replacement of the starting material. Yes, many wooden crafts of complex shape, but relatively small size, including chiseled ones, it is already now advisable to replace plastic ones. This completely eliminates the complex operations of milling, turning, grinding and finishing, and, in addition, significantly reduces the consumption of wood. With the improvement of press equipment for the manufacture of parts from plastic materials, the dimensions of parts made of plastic will continuously increase.

Normalization and unification of the dimensions of parts. When processing parts on universal single-operation machines in non-automated production, the variety of sizes of parts is not of particular importance, since the readjustment of such machines is very simple and does not require much time. On the contrary, in automated production, the changeover of interconnected machines, often a relatively complex device, takes a lot of time and is therefore highly undesirable. Therefore, the number of sizes of machined parts must, if possible, be minimized 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 part sizes. When normalizing parts, reducing their number is achieved by combining several parts with the same dimensions into one group, i.e., unifying the dimensions.

Unification is the reduction of several parts to the same dimensions.

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 workpieces have uniform sections.

Allowance normalization. The amount of machining allowance, i.e., the difference between the dimensions of the workpiece and the machined part, usually depends on the size of the parts and must be justified by technical and economic considerations. For some types of products, for example, for lumber, processing allowances are regulated by GOST. At woodworking enterprises, processing allowances are usually not regulated by anything and are set arbitrarily. A 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 means the development of a strictly justified range of allowances to save wood and ensure the stability of processing modes.

Implementation of a system of tolerances and landings. Modern tricks assembling products in assembly devices, on a conveyor, or in special assembly machines, determines increased requirements for the accuracy of manufacturing parts.

The accuracy of parts should ensure their assembly into units and products without individual fitting. To do this, the mating dimensions of the parts must be maintained within the established deviations, regulated by tolerances. When machining according to tolerances, which are assigned according to the required fit of mating parts, full or partial interchangeability of parts is ensured, and consequently, extensive mechanization and automation of technological processes and high quality products.

Since 1954, uniform standards for tolerances and landings have been established (GOST 6449 - 53). The introduction of this GOST in the woodworking industry is one of the most important conditions for the introduction of integrated automation.

Accuracy classes and type of interchangeability must 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 implementing 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 a 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 proportion.

Matches, pencils, coils, spools, shuttles, chairs, skis, as well as ready-made cases, sewing machines, watches, etc., i.e., products of a fairly stable design, produced in mass quantities, can be considered the most suitable automation objects.

degree of automation. The degree or level of process automation is an indicator that characterizes the degree of release of the 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 total labor intensity):

One of the disadvantages of assessing the level of automation through labor intensity is the lack of consideration for 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 reliability of automatic equipment.

The expediency 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 and jxxt.trw> .; i. Indeed, there are the most favorable conditions for effective integrated automation of technological processes.

If the scale of production limits the possibility of manufacturing 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 the transition from one stream to another usually requires a long changeover of equipment. Therefore, in variable-flow production, it is necessary to use equipment that does not require significant time for adjustment.

In small enterprises that produce several types of products, for example, furniture sets, kits construction details etc., complex automation of technological processes is associated with significant difficulties and is ineffective. At such enterprises, most often they strive to implement complex mechanization and partial automation, extending to individual sections of the technological process or only to its individual operations.

The automation of a single operation is reduced to the automation of the cycle of the machine and is called low 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, i.e., mechanisms and apparatus that free a person from managing the processes being performed. Depending on the purpose, automatic devices are classified as various systems automation.

The following systems are used to automate technological processes (Fig. 1): automatic control of the technological process operations necessary to obtain the final result; automatic control 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 components according to a predetermined plan, regardless of changes in external or other conditions and on the course of the technological process.

A characteristic feature of automatic control systems is the presence of a stable program for changing operations, as well as the lack of means for measuring process parameters, since the latter do not affect the operation of the systems.

The operation of the elements of automatic control systems is reliable. When any element fails, the process is usually interrupted.

Depending on the nature of the process, automatic control is divided into simple (cyclic) and software.

Simple is called automatic control of machines that repeat the same operations with the object being processed, that is, such machines, the work of which consists of the same cycles following one after another. This group includes most of the cycle woodworking machines.

Software is called automatic control, which provides for a predetermined change in individual operations of the technological process, which cannot be divided into identical cycles.

Earlier to program management referred to the control systems of machines, the movement of the working bodies of which could change from cycle to cycle, for example, printing machines, looms etc. Recently, systems that provide a quick change in the program of work of machines during the transition from one part to another are also referred to as program control.

Automatic control systems. These systems qualitatively change the course of the technological process according to a strictly defined law or maintain 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.

The failure of any control element usually does not interrupt the process, but affects its result.

Automatic regulation can be continuous, program and tracking.

The 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. The regulation of a constant parameter is, in particular, the automatic maintenance set temperature in the drying chamber.

The software includes the regulation of any parameter in time according to a certain law, for example, a predetermined change in temperature in a drying chamber.

Follow-up regulation of a parameter is similar to software regulation, but it is performed not according to a program predetermined in time, but depending on the value of another parameter, i.e., according to a program in time, unknown in advance. The follower can include, in particular, automatic temperature control in the drying chamber depending on the moisture content of the wood.

Automatic control systems. For automatic control of process parameters, safety automatic devices and devices are used to record 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 part of the regulator.

Quality control of products is carried out using various means, which, if necessary, also allow sorting of products in finished form (passive control) or in the process of its manufacture (active control). Accounting for manufactured products is carried out using various counters, often attached directly to the machine.

Control over the operation of the equipment is usually carried out using control and measuring devices attached directly to the equipment or installed on special control panels.

Basic methods of process automation

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 fundamental improvement of technological processes.

Modernization of equipment. Such automation does not change the technological process and is reduced to the modernization of non-automatic machines and their integration into a single automatic system. Automation tools in this case complement the existing basic equipment and cannot be used most rationally.

In woodworking, the first automatic and semi-automatic lines based on the use of conventional universal equipment were organized in Vitebsk and Kyiv furniture factories, Kiev Woodworking Plant, Moscow Furniture Assembly Plant No. 2 and other enterprises.

Important advantages of this automation are significant cost savings and the availability of implementation 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 new, automatic.

Since the modernization retains versatile equipment with a relatively low concentration of operations, production space is used less than in the case of the use of special multi-operation equipment.

When automating individual operations on modernized machines, the loading and unloading of the machine is automated. When automating 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 a mechanized supply of material, the work cycle is automated. Such machines include: autoplaning, thicknessing, four-sided planing, some circular saws, double-sided tenoning, three-cylinder grinding, etc. Automation of these machines is reduced to equipping them with automatic loading and unloading devices. When such machines are included in an automatic line, it is necessary that their productivity is the same and that the interoperational transport devices operate synchronously with the loading and unloading devices.

Introduction of new automatic equipment. Technological processes change according to the level development- science and technology. At present, two principles for constructing a technological process are most characteristic - 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 by one tool sequentially on one or on different machines.

Differentiation makes it possible to use separate, simple, narrow-operation machines for each operation, and, consequently, 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 space and maintenance personnel. In addition, the processing of parts on many machines reduces the accuracy of their manufacture and increases labor intensity.

The period of automation of technological processes is characterized by the principle of concentration of processing, 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 appearance of an individual electric drive, the improvement of pneumatic and hydraulic drives, and the development of reliable 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 production area.

The introduction of new automatic, predominantly multi-operational equipment is possible on the basis of a fundamental improvement in 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-operational (aggregate) specialized machines instead of universal single-operation general-purpose machines. The former are characterized by significantly higher productivity and occupy less production space.

The need for modular machine tools 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 machines should be justified in each individual case by technical and economic calculations. Reducing the cost of specialized machines 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 based on 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, it is usually sought to automate the entire cycle of work, including loading workpieces and unloading parts. Such machines are suitable both for individual work and for integration into automatic lines.

When designing automatic lines from specialized automatic equipment, options for choosing the best option much more than with the layout of lines from universal equipment.

excerpts from the book Automation of technological processes in woodworking, N. V. MAKOVSKY (attention! recognition errors are possible)

From: LidiaZaiceva,  58588 views

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