Question. Classification of machine tools by groups and their purpose.

metalworking machine- a machine designed for processing workpieces in order to form specified surfaces by removing chips or by plastic deformation. Processing is carried out mainly by cutting with a blade or abrasive tool. Machine tools for processing workpieces by electrophysical methods have become widespread. Machine tools are also used for smoothing the surface of the part, for rolling the surface with rollers. Metal-cutting machines carry out cutting of non-metallic materials, for example, wood, textolite, nylon and other plastics. Special machines also process ceramics, glass and other materials.

Classification of metal-cutting machines.

Depending on the type of processing, the cutting tool used and the layout, all commercially available machines are divided into nine groups, each group has nine types /table 1/.

Machines of the same type may differ in layout (for example, universal milling, horizontal, vertical) and kinematics, i.e. a set of links that transmit movement, design, control system, dimensions, processing accuracy, etc.

The standards establish the main dimensions that characterize the machines of each type. For lathes and cylindrical grinding machines, this is the largest diameter of the workpiece to be processed, the length of milling machines is the length and width of the table on which workpieces or fixtures are installed, for cross-planing machines, the largest stroke of the slider with a cutter.

A group of machines of the same type, having a similar layout, kinematics and design, but different basic dimensions, constitutes a size range.

The design of the machine tool of each size, designed for given machining conditions, is called a model. Each model is assigned its own code - a number consisting of several numbers and letters. The first digit indicates the group of the machine, the second - its type, the third digit or the third and fourth digits indicate the main size of the machine. For example, model 16K20 means: a screw-cutting lathe with the largest workpiece diameter of 400 mm. The letter between the second and third digits means a certain upgrade of the main base model of the machine.

According to the degree of accuracy machines are divided into 5 classes: H - normal accuracy, P - increased accuracy, V - high accuracy machines, A - extra high accuracy, C - extra precise or master machines. The model designation may include a letter characterizing the accuracy of the machine: 16K20P - a screw-cutting lathe of increased accuracy.

The letter after the first or second digit of the index indicates the modernization (constructive improvement) of the basic model of the machine, and the machine is the more modernized, the farther this letter is from the beginning of the alphabet. The letter or letters at the end of the index indicate a modification (modification) of the basic model of the machine. For example, to indicate the accuracy class of the machine, the corresponding letter is entered after the index numbers (except for class H). In models of CNC machines, at the end of the index, the letter F is entered with a number indicating the adopted control system: F1 - with digital indication and a preliminary set of coordinates; F2 - with a positional control system; FZ - with a contour control system; F4 - with a universal system for positional and contour processing. In addition, indexes associated with automatic tool change have been introduced: P - tool change by turning the turret; M - change tool from the store. Indices P and M are placed before the indices F2, FZ, F4.

Let's look at a few examples. Model 16K20PFZ is deciphered as follows: a screw-cutting lathe (first two digits) with a center height above the bed (half of the largest processing diameter) of 200 mm, another upgrade (K) of the base model 1620, increased accuracy (P), with a contour program control system ( FZ). Model 2N125 - vertical drilling machine (first two digits) with the largest drilling diameter of 25 mm, modernization H of the base model 2125. Model 6T80Sh - horizontal milling machine (first two digits), with a table with dimensions of 200x600 mm - No. O (third figure), modernization T of the base model 680, wide-universal (W).

To designate models of specialized and special machine tools, each machine-tool law is assigned a two-letter index. In the designation of the model of such a machine, numbers are added to the letters indicating serial number models. For example, EZ-9 - Yegoryevsk machine-tool plant "Komsomolets", a specialized machine for cutting gear racks;

MK-56 - Moscow Machine Tool Plant "Krasny Proletary", a drilling machine for processing turbine blades.

By weight machines are divided into light - up to 1 t, medium - up to 10 tons, heavy - over 10 tons. Heavy machines are divided into large - from 16 tons to 30 tons, actually heavy - from 30 to 100 tons, especially heavy - over 100 tons .

According to the degree of versatility distinguish between the following machines

Machine tools can be classified according to individual features or a set of features. According to the technological purpose, lathe, milling, drilling, etc. are distinguished. groups. According to the degree of versatility, they distinguish: universal machines; wide application; specialized and special. Universal machines are designed to perform a variety of jobs using various workpieces. General purpose machines are designed to perform certain jobs using workpieces of certain names. Specialized machines are designed for processing workpieces of the same name, but of different sizes (for example, processing a gear rim on a gear hobbing machine). Special machines perform a very specific type of work on one specific workpiece. According to the degree of automation, manual machines, semi-automatic machines, automatic machines, machine tools with program control are distinguished.

An automatic machine is a machine that does not require human intervention to resume the processing cycle. If you only need to press the “start” button to resume the processing cycle, then formally this is a semi-automatic machine. According to the number of main working bodies, single and multi-spindle machines, single- and multi-position machines, etc. are distinguished. According to the accuracy, there are five classes of accuracy of machine tools: "N" - normal; "P" - increased; "B" - high; "A" - especially high accuracy; "C" - especially precise machines.

Unified system adopted in Russian mechanical engineering symbols machine tools developed at ENIMS. In accordance with this system, each machine is assigned a specific code. The first two digits of the cipher determine the group and type of machine. The letter in the second or third place allows you to distinguish between machines of the same size, but with different technical characteristics. The third or fourth digit shows the nominal size of the machine. The last letter indicates various modifications of machines of the same basic model.

All metal cutting machines are divided into 10 groups, and each group into 10 types. Below: The group number and name are in italics, and the number (from 0 to 9th) and type name are in brackets.

Group 0 - backup.

Group 1 - lathes (0 - specialized automatic machines and semi-automatic machines; 1 - single-spindle automatic machines and semi-automatic machines;

2 - multi-spindle automatic machines and semi-automatic devices; 3 - revolving; 4 - drilling and cutting; 5 - carousel; 6 - turning and frontal; 7 - multi-cutting; 8 - specialized; 9 - different turning).

Group 2- drilling and boring machines (0 - reserve; 1 - vertical drilling; 2 - single-spindle semi-automatic machines;

• 3 - multi-spindle semiautomatic devices; 4 - coordinate boring;
• 5 - radial drilling; 6 - horizontal boring; 7 - diamond boring; 8 - horizontal drilling; 9 - different drilling).

Group 3- grinding and finishing machines (0 - reserve; 1 - circular grinding; 2 - internal grinding; 3 - rough grinding; 4 - specialized grinding; 5 - reserve; 6 - sharpening; 7 - surface grinding; 8 - lapping and polishing; 9 - different, working as an abrasive).

Group 4- combined machines.

Group 5 - gear and thread processing machines (0 - thread-cutting; 1 - gear-cutting for cylindrical wheels; 2 - gear-cutting for bevel gears; 3 - gear-cutting; 4 - for cutting worm pairs; 5 - for processing the ends of the teeth; 6 - thread-milling; 7 - gear-finishing and calibration; 8 - gear and thread grinding; 9 - various gear and thread processing machines).

Group 6- milling machines (0 - reserve; 1 - vertical console; 2 - continuous; 3 - reserve; 4 - copying and engraving; 5 - vertical consoleless;

6 - longitudinal; 7 - console wide-universal; 8 - horizontal console; 9 - different milling).

Group 7- planing, slotting, broaching machines (0 - reserve; 1 - longitudinal planing single-column; 2 - longitudinal planing two-column; 3 - cross-planing; 4 - slotting; 5 - broaching horizontal; 6 - reserve; 7 - broaching vertical; 8 - reserve; 9 - different planers).

Group 8- cutting machines (0 - reserve; 1 - cutting, working with a cutter; 2 - cutting, working with an abrasive wheel; 3 - cutting, working with a smooth disk; 4 - straightening and cutting; 5 - band saws; 6 - circular saws; 7 - saws hacksaws).

Group 9- different machines (1 - filing; 2 - sawing; 3 - correct and centerless peeling; 4 - balancing; 5 - for testing drills and grinding wheels; 6 - dividing machines).

The conventional size of the machine usually shows the largest size of the workpiece being machined. For example, a universal screw-cutting lathe mod. 16K20 - "20" - the height of the centers, i.e. distance from the axis of rotation of the workpiece to the guides, 200 mm; vertical drilling machine mod. 2H135 - "35" - the largest drilling diameter is 35 mm.

Introduction

Mechanical engineering is one of the most important branches in the national economy. It creates the conditions for the development of many other types of production and industries. The development of machine building itself depends on the machine tool industry. New machine tools for various technological purposes, progressive designs of cutting tools provide an automatic processing process, reduced time for setting up equipment, the possibility of multi-machine maintenance, improved product quality, labor productivity and production culture. At present, the task of increasing the efficiency of existing equipment is to increase the production of automation equipment equipped with microprocessors and small computers, as well as flexible production systems. CNC machines are gradually replacing manually operated equipment.

In the device of metal-cutting machines there is much in common. This is due to the very essence of the cutting process.

The basis of the device of metal-cutting machine tools is a set of mechanisms and other technical devices that mainly provide two movements - the movement of cutting (with a cutter, milling cutter, drill, etc.) and the movement of feeding the workpiece or cutting tool.

General information about metal cutting machines

Analysis of the design of modern metal-cutting machines

Grinding machine, in metalworking - a metal-cutting machine for processing workpieces with an abrasive tool.

In accordance with the classification adopted for metal-cutting machines, grinding machines are divided into circular and internal grinding (including centerless grinding, planetary), specialized, surface grinding, etc., working with an abrasive tool. The specificity of the tool used imposes some additional requirements on the design and construction materials: vibration resistance, wear resistance, intensive removal of abrasive dust. The main movement of the grinder is the rotation of the abrasive tool, and its speed, as a rule, is much higher than the feed rate and other movements.

The most widespread are circular grinding machines (for example, machine brand 3M196). On these machines, the workpiece is mounted on centers or in a chuck and rotated towards the grinding wheel; together with the machine table, it can reciprocate. The grinding wheel at the end of each (or double) stroke of the table receives a lateral movement to the depth of cut. On circular grinding machines, the outer cylindrical and conical surfaces and the ends of the workpieces are usually ground. On plunge-cut circular grinding machines, grinding of external cylindrical, conical and shaped surfaces is carried out in a wide range (wider than the size of the workpiece); there is no longitudinal feed here.

Internal grinding machines are designed for grinding internal surfaces of rotation. An example of such a machine is a 3K228A machine.

The most common are internal grinding machines, in which the workpiece rotates around the axis of the hole to be ground, and the grinding wheel rotates around its own axis. Longitudinal and transverse feeds are carried out in a circle. When processing holes in large workpieces that are difficult to rotate, planetary internal grinding machines are used. In these machines, the grinding wheel rotates around its own axis and around the axis of the hole being ground at the same time.

The paper considers a 3G71 surface grinding machine, which is designed for processing workpiece planes with the periphery or end face of a grinding wheel. On such machines, working on the periphery of the circle, the table with the workpiece fixed on it makes a reciprocating or rotational movement, and the rotating grinding wheel receives a transverse feed for each stroke or revolution of the table, as well as moving to the depth of cut. In surface grinders, working with the end face of the grinding wheel, in contrast to machines working with the periphery of the circle, there is no transverse feed, because. the diameter of the circle is greater than the transverse dimension of the workpiece (plunge grinding).

Specialized grinding machines are designed, as a rule, for processing parts of a given shape, for example, for grinding crankshaft journals, die parts, templates, spline parts, etc. The processing of workpieces on these machines is carried out mainly by copying, less often by bending.

The general group of grinding machines also includes machines: lapping, polishing, finishing, sharpening, spline grinding, honing, etc., working with an abrasive tool.

Knowledge of the functionally common main components of various types of metal-cutting machines allows you to better and faster become familiar with the device, control and operation of any particular machine.

Metal-cutting machines (MPC) are designed for dimensional processing of blanks by removing chips with a bladed or abrasive cutting tool.

Details, components and mechanisms of the MRS according to their fundamental purpose can be divided into carrier and guide system group(or simply, "carrier system") and drive and control group. Details and nodes of the first group provide the correct direction of rectilinear and circular movements of nodes with the workpiece (product) and tool. With the help of the mechanisms of the second group, shaping and machine control movements are carried out.

To carrier system relate:

- beds, bases, racks, columns- base units on which the rest of the fixed and movable units and mechanisms of machine tools are installed; on the base nodes, guide surfaces (or, simply, “guides”) are performed along which the movable nodes of the machine move;

- calipers, caliper carriages and slides, caliper crossbars, sliders, sleeves- parts and assemblies for maintaining and translational or rocking movement of the tool;

- tables, sledges and sledges of tables, consoles- parts and assemblies for supporting and progressive movement of workpieces;

- cases of spindle stocks, gear boxes and feed boxes- parts and assemblies for supporting and guiding the rotating parts of the machine;

- spindles and their supports, faceplates, tailstocks, rotating columns- parts and components for the rotation of tools and products.

Drive mechanisms provide rotational, translational, reciprocating, continuous and periodic movements of parts and assemblies during the process of processing the product, idle movements, transportation of workpieces from loading devices and between processing positions, clamping-unclamping of workpieces, tools, machine components, chip removal, etc. d.

Via management mechanisms the machine is started and stopped, the direction and speed of movements are changed, the cycle of the machine is controlled, etc.

1.2 Classification of machine tools

1.2.1 By technological sign, i.e. depending on the nature of the work performed and the cutting tools used, MRS are divided into 11 groups:

1) turning machines - designed mainly for processing external surfaces of rotation with cutters;

2) drilling and boring machines - designed to obtain and process holes; cutting tool - drills, countersinks, reamers, boring cutters;

3) grinding machine tools - cutting tools - abrasive grinding wheels;

4) polishing and finishing machines - designed for finishing work using abrasive bars, tapes, powders;

5) gear-cutting machines - designed for processing wheel teeth;

6)milling machine tools - processing is carried out with multi-blade tools - milling cutters;

7) planing machines - designed for processing flat surfaces with cutters;

8) split machines - designed for cutting long products, pipes;

9) lingering machine tools - processing is carried out with multi-blade tools - broaches;

10) threading machines - designed for processing helical surfaces (the group does not include lathes);

11) various machines - machines that are not included in the listed groups.

1.2.2 Depending on the degree universality , determined by the number of different parts that can be processed on a given machine, MRS are divided into universal, specialized and special.

To universal include machines general appointments designed to perform various operations on products of many types (turning screw-cutting, revolving, carousel, etc.), and wide appointments designed to perform certain operations on products of many types (turning and cutting, multi-cutting, etc.).

To specialized include machines designed for processing products of the same name and different sizes (crankshafts, pipes, couplings, bearing rings, rolls, ingots, tools, etc.).

To special include machines designed to process a specific (one) product.

1.2.3 MRS depending on precision characteristics are divided into five classes:

Class H - machines normal precision,

Class P - machines elevated precision,

Class B - machines high precision,

Class A - machines especially high precision,

Class C - especially precise machines (master machines).

Machines of class H provide processing of parts according to 7-8 qualifications of accuracy. If the indicated accuracy is conditionally taken as a unit, then class P machines provide processing accuracy 1.25 times higher, class B - 1.25 2 times higher, etc. To obtain such indicators for machining accuracy, as practice shows, the geometric accuracy of the machines themselves must increase exponentially with a higher denominator. So, the ratio between the tolerance values ​​() for most indicators of machine accuracy (spindle runout, parallelism of the spindle axis with guides, etc.) when moving from class to class is taken equal to 1.6:

Machine tools with higher accuracy classes than H are often called precision.

Class P machines are manufactured on the basis of class H machines with increased requirements for the quality of production and the selection of basic parts (often this is a better manufacture of the spindle and its supports, guides), as well as the quality of assembly and adjustment. To obtain class B machines, special designs are used for a number of critical elements of it, a higher quality of their manufacture and assembly. Class A machines are manufactured on the basis of class B machines with more stringent requirements for the main components and parts.

Class C machines are used for the manufacture of parts that determine the accuracy of precision machines, for example, dividing and reference wheels, measuring screws, etc.

Machines of classes B, A and C must be operated in thermally constant rooms.

1.2.4 MRS are classified according to weight and dimensions , on degree of automation and other parameters. There is also the concept of a "unique" machine. Unique - these are machines made in single copies (for example, machines of accuracy classes C or A, machines weighing more than 100 tons).

Modern machine tools use mechanical, electrical, electronic, pneumatic, hydraulic systems to carry out the required movements and control the technological cycle.

According to the technological purpose, lathes, milling machines, drilling machines and other groups are distinguished. Universal machines are designed to perform a variety of jobs using different workpieces. Specialized machines are designed for processing workpieces of the same name, but of different sizes (for example, processing a gear rim on a gear hobbing machine). Special machines perform a very specific type of work on one specific workpiece. According to the degree of automation, machines are distinguished:

with manual control, semiautomatic devices, automatic machines, machine tools with program control. According to the number of main working bodies, single and multi-spindle machines, single- and multi-position machines, etc. are distinguished. There are machines: H - normal; P - increased; B - high; A - especially high; With - especially exact accuracy classes.

In domestic mechanical engineering, a Unified system of symbols (codes) for machine tools has been adopted, developed in ENIMS: the first two digits of which are the group and type of the machine; the letter in the second or third place is the size of the machine (and, consequently, its specifications); the third or fourth digit is the nominal size of the machine; the last letter is a modification of machines of one basic model. All metal cutting machines are divided into 10 groups, and each group into 10 types.

Machine tools can be divided into several types depending on the application, common technological features and design features. According to the field of application, machine tools are divided into:

Machine tools for the metallurgical industry and mechanical engineering;

Machine tools for the chemical industry;

Technique for shipbuilding;

Aircraft engineering;

Industrial machines;

Equipment for metalworking, woodworking.

Separately, machine tools used in microelectronics and machine tools for instrument making are distinguished.

Metalworking machine equipment is a technique used for metal processing, production of parts of a given configuration and grinding surfaces of various profiles. It is classified according to the type of metalworking.

Lathes are equipment designed for turning external, internal, end surfaces of bodies of revolution and cutting various types of threads. It is divided into several types: turning and turning, screw-cutting, turning and turret, CNC lathes, desktop machines.

Milling machines are used for processing flat and shaped surfaces and bodies of revolution with a cutter. There are: vertical milling, universal milling, desktop milling, wide universal milling machines. As subspecies, there are vertical drilling and milling, horizontal milling, drilling and milling, universal drilling and milling equipment, CNC machines and machining milling centers.

Grinding machines are equipment designed for finishing parts by removing the upper layers from their surface with a high degree of accuracy. Machines can be round, inside, flat and centerless.

Drilling machines are used for drilling blind and through holes in solid material. The technique allows you to drill, ream, ream and cut internal threads. Meet horizontally, vertically and radially drilling.

Band saws are designed for cutting wood or metal products. Types: portal, two-column, console, horizontal, desktop-household machines.

Boring machines involve the processing of large parts by drilling, cutting, trimming, turning, etc.

The sharpening machine is used for sharpening and regrinding metal-cutting tools.

Balancing machines are designed to measure and locate the static or dynamic imbalance of rotating parts.

Slotting machines are necessary for processing flat and shaped surfaces, keyways, grooves.

Rolling machines - equipment that processes sheets by bending to give the product a cylindrical shape.

Machining centers allow parts to be subjected to complex processing.