Product Parameter is a quantitative characteristic of its properties. The most important parameters are the characteristics that determine the purpose of the product and the conditions for its use:

dimensional parameters (size of clothes and shoes, capacity of dishes);

weight parameters (weight of individual types of sports equipment);

parameters characterizing the performance of machines and devices (performance of fans and floor polishers, vehicle speed);

energy parameters (engine power, etc.).

Products with a specific purpose, operating principle and design, i.e. products of a certain type are characterized by a number of parameters. A set of set parameter values ​​is called a parametric series. A type of parametric series is a size series. For example, for fabrics, the size range consists of individual values ​​for the width of fabrics, for dishes - individual values ​​for capacity. Each size of a product (or material) of the same type is called a standard size. For example, there are now 105 standard sizes of men's clothing and 120 standard sizes of women's clothing.

The process of standardization of parametric series (parametric standardization) consists in choosing and justifying the appropriate nomenclature and numerical values ​​of the parameters. This problem is solved using the system of preferred numbers, discussed in detail in the previous topic.

The use of a system of preferred numbers allows not only to unify the parameters of a certain type of product, but also to link the parameters of products of different types. For example, the practice of standardization in mechanical engineering has shown that parametric series of parts and assemblies should be based on parametric series of machines and equipment. In this case, it is advisable to be guided by the following rule: a number of machine parameters according to R5 must correspond to a number of part sizes according to R10, a number of machine parameters according to R10- a range of part sizes according to R20, etc.

In order to more efficiently use containers for cans and vehicles for their transportation, it is proposed to build a number of carrying capacities of railway cars and vehicles, a number of sizes of containers, boxes and individual cans to build in a row R5.

Product unification. Activities to rationally reduce the number of types of parts and units of the same functional purpose are called product unification. It is based on classification and ranking, selection and simplification, typification and optimization of finished product elements. The main directions of unification are:

development of parametric and standard size ranges of products, machines, equipment, devices, components and parts;

development of standard products in order to create unified groups of homogeneous products;

development of unified technological processes, including technological processes for specialized production of products of cross-industry use;

restriction to a reasonable minimum range of products and materials permitted for use.

The results of unification work are presented in different ways: these can be albums of standard (unified) designs of parts, assemblies, and assembly units; standards of types, parameters and sizes, designs, brands, etc.

Depending on the area of ​​implementation, the unification of products can be inter-industry (unification of products and their elements of the same or similar purpose, manufactured by two or more industries); industry and factory (unification of products manufactured by one industry or one enterprise).

Depending on the methodological principles of implementation, unification can be intraspecific (families of similar products) and interspecific or interproject (units, assemblies, parts of different types of products).

The degree of unification is characterized by the level of product unification - the saturation of products with standardized, including standardized, parts, assemblies and assembly units. One of the indicators of the level of unification is the coefficient of applicability (unification) TO,%, which is calculated by the formula

Where P - total number of parts in the product, pcs.; n 0 - number of original parts (developed for the first time), pcs.

The applicability coefficient can be calculated in relation to the unification of parts for general machine-building (OMP), inter-industry (IP), industrial (OP) applications.

According to the plan for increasing the level of unification of engineering products, it is envisaged to reduce the share of original products and, accordingly, increase the share of products (parts, assemblies) of weapons of mass destruction, MP, and OP.

Applicability factors can be calculated: for one product; for a group of products that make up a type-size (parametric) series; for a structurally unified series.

An example of the use of unification in a standard-size range of products can be GOST 26678 for a parametric range of refrigerators. The standard parametric series includes 17 models of refrigerators and three models of freezers; the applicability rate of the series is 85%. GOST specifies a list of components that are subject to unification within a parametric series (for example, refrigeration units of two-chamber refrigerators with a chamber volume of 270 and 300 cm 3 and a low-temperature compartment volume of 80 cm 3), and a list of components that are subject to unification within one standard size (for example , refrigeration unit by connection dimensions, condenser).

Aggregation is a method of creating machines, instruments and equipment from individual standard unified units that are reused to create various products based on geometric and functional interchangeability. For example, the use of boards of 15 sizes and standard boxes of three sizes in furniture production makes it possible to obtain 52 types of furniture with different combinations of these elements.

Aggregation is very widely used in mechanical engineering and radio electronics. The development of mechanical engineering is characterized by the complication and frequent replacement of machine designs. To design and manufacture a large number of different machines, it was necessary first of all to divide the machine design into independent assembly units (aggregates) so that each of them performed a specific function in the machine, which made it possible to specialize the production of units as independent products, the operation of which can be checked independently of the whole cars.

The division of products into structurally complete units was the first prerequisite for the development of the aggregation method. Subsequent analysis of machine designs showed that many units, components and parts, different in design, perform the same functions in a variety of machines. Generalization of particular design solutions through the development of unified units, assemblies and parts has significantly expanded the capabilities of this method.

Currently on the agenda is a transition to the production of equipment based on large units (modules). The modular principle is widespread in radio electronics and instrument making; This is the main method for creating flexible manufacturing systems and robotic systems.

Comprehensive standardization. With complex standardization (CS), a purposeful and systematic establishment and application of a system of interrelated requirements is carried out both for the object of complex standardization as a whole and for its main elements in order to optimally solve a specific problem. In relation to products, this is the establishment and application of interrelated requirements for the quality of finished products, raw materials, materials and components necessary for their production, as well as conditions for preservation and consumption (operation). Comprehensive standardization ensures the interconnection and interdependence of related industries for the joint production of a finished product that meets the requirements of state standards. For example, the norms and requirements specified in the car standard affect metallurgy, bearing, chemical, electrical and other industries. The quality of a modern car is determined by the quality of more than 2000 products and materials - metals, plastics, rubber and electrical products, varnishes, paints, oils, fuel, lubricants, light industry products, pulp and paper industry, etc. In such cases, separate standards, even when they include promising indicators are laid down, they cannot always provide the desired results.

Comprehensive standardization makes it possible to establish the most technically rational parametric series and range of industrial products,

eliminate its excessive diversity, unjustified heterogeneity, create a technical basis for organizing mass and continuous production at specialized enterprises using more advanced technology, accelerate the introduction of the latest technology and provide an effective solution to many issues related to improving the quality of products, their reliability, durability, maintainability, reliability under operating (consumption) conditions.

The main criteria for selecting CS objects are the technical and economic feasibility of standardization and the level of technical perfection of products. The principles of comprehensive standardization are based on identifying the relationships between the quality indicators of the components of the product and objects of labor. It is characterized by three main methodological principles:

consistency(establishment of interrelated requirements in order to ensure an appropriate level of quality);

optimality(determination of the optimal nomenclature of CS objects, composition and quantitative values ​​of their quality indicators);

program planning(development of special CS programs for objects, their elements included in state, industry and republican standardization plans).

One of the main indicators that determine the degree of comprehensive standardization is the integral coefficient of product standardization coverage Kntt obtained by multiplying partial coefficients characterizing the level of standardization of raw materials, semi-finished products, structural parts and components, components, equipment, test methods, finished products, etc.: Kint= K1 K2 K3... K p, Where, K p- partial standardization coefficients for each structural element, component included in the product.

Partial coefficient TO,%, represents the ratio of the number of developed regulatory and technical documents for standardized structural elements (To ST) to the total number of regulatory and technical documents required for the production of a given product (Ktot), i.e.

K=(Kst/Ktot)*100.

Partial standardization coefficients are divided into groups according to their relation to tools (equipment, equipment, tools, etc.); to objects of labor (raw materials, supplies, semi-finished products, etc.).

In modern conditions, a tool for the practical organization of work on the CS of products is the development and implementation of comprehensive standardization programs (CSP). They are aimed at solving the most important national economic problems, provide for “end-to-end” requirements for raw materials, materials, semi-finished products, parts, assemblies, components, equipment, tools, technical means of control and testing, metrological support, methods of organization and technological preparation of production, storage, transportation regulating the working conditions to achieve the technical level and quality of products established by the scientific and technical documentation. Many PKS are large inter-industry complexes.

Due to the complexity of creating and mastering new highly efficient types of raw materials, materials, products, it is advisable to develop plans and programs for comprehensive standardization for five or more years. The development of specific standards should be planned on a yearly basis.

One of the most serious issues in the methodology of program-target planning of comprehensive standardization is assessing the effectiveness of PCS products. It can be carried out at four stages of planning: approval of the list of PKS, development of the PKS project, scientific and technical examination of the project, implementation. The reliability of the assessment of the effectiveness of the PCS is of great importance, since it is used to make a decision on the advisability of its implementation.

When making the final decision, the need to develop and implement a PCS for regulatory and technical support of previously planned targeted comprehensive programs is taken into account.

In the automotive and agricultural engineering industry, a comprehensive standardization program is being implemented, aimed at maximizing the unification of the designs of general-purpose parts and components. For the purposeful implementation of this work, albums of working drawings of standardized units and parts have been compiled, normative and technical documentation has been developed for the organization of specialized production and the development of standardized products directly at factories that manufacture agricultural machines. It has been established that it is mandatory to use standardized components and parts when designing new agricultural machines and using them as spare parts for the existing fleet of machines.

Advanced standardization. The method of advanced standardization consists in establishing norms and requirements for standardization objects that are higher than those already achieved in practice, and which, according to forecasts, will be optimal in the future.

Standards should not only record the achieved level of development of science and technology, since due to the high rate of obsolescence of many types of products, they can become a brake on technical progress. In order for standards not to slow down technical progress, they must establish long-term quality indicators indicating the time frame for their provision by industrial production. Advanced standards should standardize promising types of products, mass production of which has not yet begun or is in the early stages.

Anticipatory standardization includes the use of progressive international standards and standards of individual foreign countries in industry standards (organization standards) before their adoption in our country as state standards.

In some cases, advanced standards influence the organization of specialized production of completely new types of products. For example, in the late 1980s. There was an approval of the international standard for the audio compact disc before the production of the product itself began. This made it possible to ensure full compatibility of the CD with other technical means and thereby avoid unnecessary costs.

The production of new types of products, for example: machines, technological equipment, household appliances, etc., can lead to the production of an excessively large range of products that are similar in purpose and slightly different in design and size. A rational reduction in the number of types and sizes of manufactured products, unification and aggregation of components can significantly reduce the cost of production.

Cost reduction is achieved while simultaneously increasing serial production, developing specialization, intersectoral and international cooperation in production, which is achieved by developing standards for parametric series of similar products. Satisfying market demand and ensuring quality remains the main condition. Any product is characterized by parameters that reflect the diversity of its properties, and there is a certain list of parameters that are advisable to standardize. The range of standardized parameters should be minimal, but sufficient to assess the performance characteristics of this type of product and its modifications.

Analyzing the parameters, the main and main parameters of the products are identified.

The main parameter is called, which determines the most important performance indicator of the product. The main parameter does not depend on technical improvements of the product and manufacturing technology; it determines the indicator of the direct purpose of the product.

For example, the main parameter of an overhead crane is its lifting capacity. The main parameters of a lathe are the height of the centers and the distance between the centers of the headstock and tailstock, which determine the overall dimensions of the workpieces being processed. A gearbox is characterized by a gear ratio, an electric motor by power, measuring instruments by a measurement range, etc.

Main parameter taken as a basis when constructing a parametric series. The choice of the main parameter and the determination of the range of values ​​of this parameter must be technically and economically justified; the extreme numerical values ​​of the series are selected taking into account the current and future need for these products, for which marketing research is carried out.

Parametric series is a naturally constructed set of numerical values ​​of the main parameter of a product of one functional purpose and operating principle within a certain range. The main parameter serves as the basis for determining the numerical values ​​of the main parameters, since it expresses the most important operational property.

The main parameters are called, which determine the quality of a product as a set of properties and indicators that determine the product’s suitability for its purpose. For example, for metal-cutting equipment the following can be taken as the main ones: processing accuracy, power, spindle speed, productivity.

For measuring instruments the main parameters are: measurement error, scale division, measuring force.

The main and main parameters are interrelated, therefore in practice the main parameters are expressed through the main parameter. For example, the main parameter of a piston compressor is the cylinder diameter, and one of the main parameters is productivity, which are interconnected by a certain relationship.

The parametric series is called standard size or just size range, if its main parameter relates to the geometric dimensions of the product. On the basis of standard-size parametric series, design series of specific types or models of products of the same design and the same functional purpose are developed.

Parametric, standard-size and design series of machines are built based on the proportional change in their operational indicators (power, productivity, traction force, etc.) taking into account the theory of similarity. In this case, the geometric characteristics of machines (working volume, cylinder diameter, wheel diameter for rotary machines, etc.) are derived from operational indicators and, within a number of machines, can change according to patterns that differ from the patterns of changes in operational indicators.

Slide 6.3.3.1. Design series of piston machine

When constructing parametric, standard-size and structural series of machines, it is advisable to observe the mechanical and thermodynamic similarity of the working process, ensuring equality of the parameters of the thermal and power stress of the machines as a whole and their parts. This approach leads to geometric similarity. For example, for internal combustion engines the following similarity conditions apply:

a) equality of the average effective pressure pe, depending on the pressure and temperature of the fuel mixture at the suction;

b) equality of the average piston speed vп = S n /30 (S - piston stroke; n - engine speed) or equality of the product D n, where D is the cylinder diameter. Based on the theory of similarity, it is possible to move from the thermal and power parameters of the engine to its geometric parameters. Then, the main parameter will be D, which makes it possible to create a number of geometrically similar engines with the ratio S / D = const, in which the specified thermodynamic and mechanical criteria for the similarity of the working process will be observed. Moreover, all geometrically similar engines will have the same efficiency, fuel consumption, thermal and power intensity and power. The gradation of cylinder wall thickness h and diameter D in the rows will be the same.

Standards for parametric series provide for the production of products that are progressive in their characteristics. Such series must have the properties of establishing intra-type and inter-type unification and aggregation of products, as well as the ability to create various modifications of products based on aggregation. In most cases, the numerical values ​​of the parameters are selected from the series of preferred numbers, especially when the series is uniformly saturated in all its parts; an example of such a series with slight rounding of numbers is presented on the slide.

Slide 6.3.3.2. Structural range of presses

In mechanical engineering, a number of preferred numbers R10 are most widely used. For example, for longitudinal grinding machines, the largest width B of the workpieces forms the row R10, i.e. B is equal to: 200; 250; 320; 400; 500 630; 800; 1000; 1250; 1600; 2000; 2500; 3200 mm.

The R10 series is also established for the rated power of electrical machines. According to the R10 series, the diameters of three-sided disk cutters are accepted, D is equal to: 50; 63; 80; 100 mm. In some cases, the R20 and R40 series are used, for example, for piston compressors with a cylinder diameter of 67.5 mm, the nominal capacity is set according to the R20/3 series.

Parametric and standard size series are series of products that ensure the implementation of the volume of work corresponding to their passport data, with the quality indicators established by the technical specifications, subject to minimizing costs and obtaining maximum profits. Thus, inter-industry unification is achieved.

Structurally unified series is a naturally constructed set of products: machines, instruments, assemblies or assembly units, including a basic product and its modifications of the same or similar functional purpose and products with similar or similar kinematics, pattern of working movements, layout and other characteristics. Examples of this approach to standardization of product parameters are inter-industry unification carried out for trucks, wheeled and tracked vehicles, agricultural and road cleaning equipment. The creation of structurally unified series in the production of household appliances, such as washing machines, refrigerators, food processors, etc., has become especially widespread.

There are cases when it is advisable to use mixed series, in which the number of series members increases in the range of the highest frequency of use of products. Thus, the increased demand of consumers for products with characteristics in specific value ranges is taken into account. Therefore, when developing and launching products into production, marketing is carried out in order to establish the distribution density of the applicability of products with different values ​​of the main parameters. For example, in general mechanical engineering, about 90% of all gear modules used are within the range of 1 - 6 mm. The maximum applicability value falls on wheels with a module of 2-4 mm. Taking into account the applicability, the standard provides for a number of modules the largest number of gradations in the range of 2-4 mm.

The minimum and maximum values ​​of the main parameter, as well as the frequency of the series, are established after a feasibility study, taking into account current needs and future increases in demand. In addition, the achievements of science and technology and the possible prospects for improving the quality of this type of product while reducing the cost of production are taken into account.

Parametric series, types and standards of construction machines

Parametric (standard-size) series - series of machines of the same type, differing in the value of the main parameter, are established to reduce the production of machine standard sizes, the possibility of unification, creating modifications on basic machines, and simplifying their operation. Rows of machines are built on the basis of preferred numbers, rows of main parameters.

The parametric series of the main construction machines are adopted as follows: – single-bucket excavators: bucket capacity, m3-0.15; 0.25; 0.4; 0.63; 1; 1.6; 2.5; – bulldozers: traction class, t - 6; 10; 15; 25; 35; 50; 75; – tower cranes: load moment, t-m - 100; 160; 250; 400; 630; 1000; – self-propelled jib cranes: lifting capacity, t - 4; 6.3; 10; 16; 25; 40; 63; 100; 160; 250; 400; 630; 1000.

But jib cranes have been developed and are being introduced, the lifting capacity of which differs from the lifting capacity of the standard range, for example, the KS-3577 truck crane with a lifting capacity of 12.5 tons; truck crane KS-4562 with a lifting capacity of 20 tons; cranes on a special pneumatic tractor MAZ-547A-KS-7571 and KS-8571 with a lifting capacity of 80 and 125 tons.

The following series are also regulated: nominal speeds for lifting machines with a flexible rope lifting device; rated rotation speeds of the rotary part; nominal lifting heights; maximum hook reach.

Types. The development of new machines is carried out taking into account promising types.

An example of the type of jib cranes with a lifting capacity of up to 25 tons, developed by the Autocrane software, is given in table. 1.1.

Table 1.1
Type of jib cranes

Construction Machinery Standards. All construction machines are designed and manufactured in full compliance with the standards.

By scope they distinguish: state standards (GOST); industry standards (OST); standards of enterprises and associations (STP); international standards.

The main type of GOST is “Technical conditions”. The “Basic Parameters” and “Technical Requirements” standards have been retained for individual machines.

In addition to these types, there are “General Technical Requirements” (GTR) standards, which are promising scientific and technical documents.

The typical composition of GOST “Technical Conditions” is as follows: its area of ​​distribution, main parameters, technical safety requirements, completeness of delivery, acceptance rules, test methods, labeling, packaging, transportation and storage, operating instructions, manufacturer’s warranties.

GOST “General Technical Requirements” provides a limited number of basic parameters and indicators.

For each group of construction machines, indicators of their technical level and quality are provided, differentiated by two levels, which differ in the beginning of the validity period of the standard from the moment the machines are produced.

Each system covers a different number of standards. In turn, each standard unites a group of construction machines. As a rule, the standard is valid for 5 years, and the start and end dates of its application are indicated.

In addition to standards for construction equipment, there are standards that separately regulate indicators and provisions related to the operation of machines.

For construction machines supplied for export, special export supplements are being developed to GOST “Technical Conditions”.

Among the standards for construction equipment there are standards for the training of machinists and repair workers.

When we and foreign companies jointly produce construction machines, the operational documentation (passport, operating instructions) makes reference to the basic technical standards, technical supervision rules, our standards and the country whose companies are involved in the manufacture of this machine.

In mining engineering

They are developed with the aim of eliminating unwanted and unjustified diversity, increasing serial production and, on this basis, improving the quality and reducing the cost of technological machines, installations and equipment.

Type – a set of technological machines that represents economic feasibility and a minimum range that meets the industry’s need for them.

Parametric series – the numerical value of one or more parameters that characterize the main operational indicators and uniquely determine the size of the machines.

The basis for establishing a parametric range of standard machines is preferred number system. Many years of practice have shown that the best range of parameters is geometric progression (GOST 8032-56).

Currently, the types have been approved and are widely used for all types of mining transport (electric locomotives, trolleys, belt and scraper conveyors), loading and loading-and-delivery machines, excavators, mining dump trucks, etc.

Based on the types developed and approved standards, which regulate the most important parameters of machines (performance, dimensions, weight, type of drive). The standards have the following categories: international (ST SEV), state (GOST), republican (STB), industry (OST) and enterprise standards (SP) and technical specifications (THAT).

The introduction of standards helps to reduce the range of products, unify individual components of standard machines, increase their technical level, serial production and maintainability.

Performance qualities of mining machines

Mining machines must best meet the needs of the national economy and have high performance indicators. The most significant of them can be divided into three groups :

· Technological , i.e. suitability of the machine to perform certain types of work;

· Technical and economic , defining productivity and efficiency of work performed;

· General technical – ensuring driver comfort and safety.

Technological quality is a series of properties related to cross-country ability, the ability to provide certain work parameters and maneuverability.

Estimated indicators cross-country ability: pressure in the contact patch of the propeller with the ground, soil deformation, engine power reserve for movement, ground clearance (clearance), type and design features of the propeller;

Possibility of providing certain parameters of the work performed can be characterized, for example, by milling depth, load capacity, unloading height and other parameters depending on the purpose of the machine.

Main parameters maneuverability are: the radius and angular speed of the turn, the width of the lane during the turn in the working and transport positions of the actuators.

Technical and economic – it's productivity and efficiency.

Productivity is characterized by the volume of work performed per unit of time, subject to compliance with the specified technical conditions for a given technological operation. There are theoretical (constructive), technical and operational performance.

Theoreticalperformance– This the amount of useful work that a machine could perform, under certain design conditions accepted by the developer and specified in the technical passport, is measured by a quantitative indicator of the work performed per second(m 3 /s, kg/s, pcs/s). It depends on the engine power, the range of traction forces and speeds, and the type of working parts.

Technical– this is the actual performance of the machine at one o'clock, which it can show under certain conditions without taking into account downtime for short periods of time (m 3 / hour, kg / hour, pcs / hour).

Operational- actual productivity, taking into account sluggish passes as well as machine downtime for technical and organizational reasons; as a rule, it is characterized by the conditional volume of work performed or products produced per shift or per day, per month or per year.

Taking into account the above definitions, for the same machine performing the same work, theoretical productivity is always of greatest importance, technical productivity is somewhat less, and operational productivity is then, in decreasing order.

Profitability is determined by the cost of work performed or the cost of manufactured products and depends on reliability, energy intensity, material intensity, cost of maintenance and repair work, as well as labor costs for the driver or maintenance team.

General technical qualities are associated with ensuring ease of operation, ease of maintenance, sanitary and hygienic conditions, driver safety and are assessed by noise level, vibration, dust, gas pollution, microclimate in the cabin, and readiness for work.

Modern machines must also meet the requirements of technical aesthetics (design).

RELIABILITY OF MINING MACHINES

Basic concepts of reliability (GOST 13377-75)

Reliability – the property of an object to preserve over time, within established limits, all parameters that ensure the performance of the required functions while observing the specified operating conditions.

Reliability theory includes seven sections: mathematical theory of reliability; reliability according to individual failure criteria (“failure physics”); calculation and forecasting of reliability; measures to improve reliability; reliability control (testing, statistical control, organization of observations) and technical diagnostics; recovery theory; economics of reliability.

Generalized objects Reliability theory includes:

Product– a unit of product produced by a given manufacturer (excavator, conveyor, drilling machine, milling cutter, cutter, etc.).

Element– any product whose reliability is studied as a whole, regardless of its structure and design.

System– a set of jointly acting elements that perform specified functions, while the reliability of a given product is determined depending on the reliability of its component parts (elements).

The concepts of element and system are transformed depending on the task at hand. A working body, for example, when establishing its own reliability, is considered as a system consisting of individual elements - a drive, a cutter and parts, and when studying the reliability of a mining machine, it is an element similar to the engine, frame, propeller, and cabin with controls included in it.

Products are divided into unrecoverable , which cannot be restored at the consumer enterprise and must be completely replaced; And recoverable, which are subject to restoration by the consumer through repair and replacement of individual elements. In mining machines, as a rule, non-renewable products include the executive elements of the working bodies (cutters, teeth, pins, etc.) as well as standard mass-produced products (fasteners, cuffs, bearings, etc.).

Reliability is characterized by the following states And events:

Performance– the state of the product in which it is capable of normally performing specified functions, maintaining operational parameters within the limits specified in the technical documentation.

Serviceability- the state of the product in which it satisfies not only the basic, but also auxiliary requirements. A working product must be functional.

Malfunction– the state of the product in which it does not meet at least one of the requirements from the technical documentation. There are faults that do not lead to failures, and faults and their combinations that lead to failures.

Kolchkov V.I. METROLOGY, STANDARDIZATION AND CERTIFICATION. M.: Textbook

2. Standardization

2.3. Methodological basis of standardization

2.3.3. Parametric series

The production of new types of products, for example: machines, technological equipment, household appliances, etc., can lead to the production of an excessively large range of products that are similar in purpose and slightly different in design and size. Rational reduction in the number of types and sizes of manufactured products, unification and aggregation components can significantly reduce the cost of production.

Cost reduction is achieved while simultaneously increasing serial production, developing specialization, intersectoral and international cooperation in production, which is achieved by developing standards for parametric series of similar products. Satisfying market demand and ensuring quality remains the main condition. Any product is characterized by parameters that reflect the diversity of its properties, and there is a certain list of parameters that are advisable to standardize. The range of standardized parameters should be minimal, but sufficient to assess the performance characteristics of this type of product and its modifications.

Analyzing the parameters, we distinguish main and main parameters of products.

Main is a parameter that determines the most important performance indicator of a product. The main parameter does not depend on technical improvements of the product and manufacturing technology; it determines the indicator of the direct purpose of the product.

For example, the main parameter of an overhead crane is its lifting capacity. The main parameters of a lathe are the height of the centers and the distance between the centers of the headstock and tailstock, which determine the overall dimensions of the workpieces being processed. A gearbox is characterized by a gear ratio, an electric motor by power, measuring instruments by a measurement range, etc.

The main parameter is taken as the basis when constructing a parametric series. The choice of the main parameter and the determination of the range of values ​​of this parameter must be technically and economically justified; the extreme numerical values ​​of the series are selected taking into account the current and future need for these products, for which marketing research is carried out.

Parametric series is a naturally constructed set of numerical values ​​of the main parameter of a product of one functional purpose and operating principle within a certain range. The main parameter serves as the basis for determining the numerical values ​​of the main parameters, since it expresses the most important operational property.

Main call the parameters that determine the quality of a product as a set of properties and indicators that determine the suitability of the product for its purpose. For example, for metal-cutting equipment the following can be taken as the main ones: processing accuracy, power, spindle speed, productivity.

Formeasuring instruments the main parameters are: measurement error, scale division, measuring force.

The main and main parameters are interrelated, so sometimes it is convenient to express the main parameters through the main parameter. For example, the main parameter of a piston compressor is the cylinder diameter, and one of the main parameters is productivity, which are interconnected by a certain relationship.

The parametric series is called standard size or simply size range, if its main parameter relates to the geometric dimensions of the product. On the basis of standard-size parametric series, design series of specific types or models of products of the same design and the same functional purpose are developed.

Parametric, standard-size and design series of machines are built based on the proportional change in their operational indicators (power, productivity, traction force, etc.) taking into account the theory of similarity. In this case, the geometric characteristics of machines (working volume, cylinder diameter, wheel diameter for rotary machines, etc.) are derived from operational indicators and, within a number of machines, can change according to patterns that differ from the patterns of changes in operational indicators.

Rice. 2.1. Design series of piston machine

When constructing parametric, standard-size and structural series of machines, it is advisable to observe the mechanical and thermodynamic similarity of the working process, ensuring equality of the parameters of the thermal and power stress of the machines as a whole and their parts. This approach leads to geometric similarity. For example, for internal combustion engines the following similarity conditions apply: a) equality of the average effective pressure re, depending on the pressure and temperature of the fuel mixture at the suction; b) equality of the average piston speed v n = S n/30 (S- piston stroke; n- engine speed) or equality of the product D n, Where D- cylinder diameter. Based on the theory of similarity, it is possible to move from the thermal and power parameters of the engine to its geometric parameters. Then the main parameter will be D(Fig. 2.1), which makes it possible to create a number of geometrically similar engines with the ratio S/ D = const, in which the specified thermodynamic and mechanical criteria for the similarity of the working process will be observed. Moreover, all geometrically similar engines will have the same efficiency, fuel consumption, thermal and power intensity and power. Gradation of cylinder wall thickness h and diameter D in the ranks will be the same.

Standards for parametric series provide for the production of products that are progressive in their characteristics. Such series must have the properties of establishing intra-type and inter-type unification and aggregation of products, as well as the ability to create various modifications of products based on aggregation. In most cases, the numerical values ​​of the parameters are selected from the series of preferred numbers, especially when the series is uniformly saturated in all its parts; an example of such a series with slight rounding of numbers is shown in Fig. 2.2.

Rice. 2.2. Structural range of presses

In mechanical engineering, a number of preferred numbers are most widely used R 10. For example, for longitudinal grinding machines, the largest width IN processed products form a series R 10, i.e. B is equal to: 200; 250; 320; 400; 500 630; 800; 1000; 1250; 1600; 2000; 2500; 3200 mm.

Row R 10 is also established for the rated powers of electrical machines. By row R 10 accepted diameters of three-sided disk cutters, D equals: 50; 63; 80; 100 mm. In some cases, rows are used R 20 and R 40, for example, for piston compressors with a cylinder diameter of 67.5 mm, the nominal capacity is set according to the series R 20/3.

Parametric and standard size series are series of products that ensure the implementation of the volume of work corresponding to their passport data, with the quality indicators established by the technical specifications, subject to minimizing costs and obtaining maximum profits. Thus, it is achieved intersectoral unification.

Structurally unified series is a naturally constructed set of products: machines, instruments, assemblies or assembly units, including a basic product and its modifications of the same or similar functional purpose and products with similar or similar kinematics, pattern of working movements, layout and other characteristics. Examples of this approach to standardization of product parameters are inter-industry unification carried out for trucks, wheeled and tracked vehicles, agricultural and road cleaning equipment. The creation of structurally unified series in the production of household appliances, for example washing machines, refrigerators, food processors, is especially widespread and etc.

There are cases when it is advisable to use mixed series, in which the number of series members increases in the range of the highest frequency of use of products. Thus, the increased demand of consumers for products with characteristics in specific value ranges is taken into account. Therefore, when developing and launching products into production, marketing is carried out in order to establish the distribution density of the applicability of products with different values ​​of the main parameters. For example, in general mechanical engineering, about 90% of all gear modules used are within the range of 1 - 6 mm. The maximum applicability value falls on wheels with a module of 2-4 mm. Taking into account the applicability, the standard provides for a number of modules the largest number of gradations in the range of 2-4 mm.

The minimum and maximum values ​​of the main parameter, as well as the frequency of the series, are established after a feasibility study, taking into account current needs and future increases in demand. In addition, the achievements of science and technology and the possible prospects for improving the quality of this type of product while reducing the cost of production are taken into account.

Theory Workshop Tasks Information