Cutters for a CNC machine. Classification of cutters for a metal lathe - types, purpose

Engineering systems 12.09.2023

Engineering systems

Specialists who often use lathe cutters when performing metal work, as well as those who sell these products or supply machine-building enterprises, are well aware of the types of these tools. For those who rarely come across turning tools in their practice, it is quite difficult to understand their types, which are presented in a wide variety on the modern market.

Types of turning tools for metal processing

Lathe cutter design

In the design of any cutter used for, two main elements can be distinguished:

holder with which the tool is fixed on the machine;
a working head through which metal processing is performed.

The working head of the tool is formed by several planes, as well as cutting edges, the sharpening angle of which depends on the characteristics of the workpiece material and the type of processing. The cutter holder can be made in two versions of its cross section: square and rectangle.

According to their design, turning cutters are divided into the following types:

straight - tools in which the holder together with their working head are located on one axis, or on two, but parallel to each other;
curved cutters - if you look at such a tool from the side, you can clearly see that its holder is curved;
bent - the bend of the working head of such tools in relation to the axis of the holder is noticeable if you look at them from above;
drawn - with such cutters the width of the working head is less than the width of the holder. The axis of the working head of such a cutter can coincide with the axis of the holder or be offset relative to it.

Classification of cutters for turning

The classification of turning tools is regulated by the requirements of the relevant GOST. According to the provisions of this document, cutters are classified into one of the following categories:

one-piece instrument made entirely of . There are also incisors that are made entirely from, but they are used extremely rarely;
cutters, onto the working part of which a plate made of hard alloy is soldered. Instruments of this type are most widespread;
cutters with removable carbide plates, which are attached to their working head using special screws or clamps. Cutters of this type are used much less frequently compared to instruments of other categories.

(click to enlarge)

The cutters also differ in the direction in which the feeding movement occurs. Yes, there are:

left-hand turning tools - during processing they are fed from left to right. If you place your left hand on top of such an incisor, then its cutting edge will be located on the side of the bent thumb;
right incisors - the type of tool that has become most widespread, the feed of which is carried out from right to left. To identify such a cutter, you need to place your right hand on it - its cutting edge will be located, accordingly, on the side of the bent thumb.

Depending on what work is performed on turning equipment, cutters are divided into the following types:

for finishing metal work;
for rough work, which is also called roughing;
for semi-finishing work;
for performing delicate technological operations.

In the article we will look at the entire range and determine the purpose and features of each of them. An important clarification: no matter what type the cutters are, certain grades of hard alloys are used as the material for their cutting inserts: VK8, T5K10, T15K6, much less often T30K4, etc.

A tool with a straight working part is used to solve the same problems as bent-type cutters, but it is less convenient for chamfering. Basically, such a tool (by the way, not widely used) is used to process the outer surfaces of cylindrical workpieces.

The holders of such cutters for a lathe are made in two main sizes:

rectangular shape – 25x16 mm;
square shape - 25x25 mm (products with such holders are used to perform special work).

These types of cutters, the working part of which can be bent to the right or left side, are used for processing the end part of the workpiece on a lathe. They are also used to remove chamfers.

Tool holders of this type can be made in various sizes (in mm):

16x10 (for training machines);
20x12 (this size is considered non-standard);
25x16 (the most common size);
32x20;
40x25 (products with a holder of this size are made mainly to order; they are almost impossible to find on the open market).

All requirements for metal cutters for this purpose are specified in GOST 18877-73.

Such tools for a metal lathe can be made with a straight or bent working part, but they do not focus on this design feature, but simply call them through-thrust tools.

A continuous thrust cutter, which is used to process the surface of cylindrical metal workpieces on a lathe, is the most popular type of cutting tool. The design features of such a cutter, which processes the workpiece along the axis of its rotation, make it possible to remove a significant amount of excess metal from its surface even in one pass.

Holders for products of this type can also be made in various sizes (in mm):

16x10;
20x12;
25x16;
32x20;
40x25.

This tool for a metal lathe can also be made with a right or left bend of the working part.

Outwardly, such a scoring cutter is very similar to a pass-through cutter, but it has a different cutting plate shape - triangular. With the help of such tools, workpieces are processed in a direction perpendicular to their axis of rotation. In addition to bent ones, there are also persistent types of such turning cutters, but their scope of application is very limited.

Cutters of this type can be manufactured with the following holder sizes (in mm):

16x10;
25x16;
32x20.

The parting cutter is considered the most common type of metal lathe tool. In full accordance with its name, such a cutter is used for cutting workpieces at right angles. It is also used to cut grooves of varying depths on the surface of a metal part. Determining that what you have in front of you is a cutting tool for a lathe is quite simple. Its characteristic feature is a thin leg onto which a hard alloy plate is soldered.

Depending on the design, there are right- and left-handed types of cutting tools for metal lathes. It is very easy to distinguish them from each other. To do this, you need to turn the cutter over with the cutting plate down and see which side its leg is located on. If it is on the right, then it is right-handed, and if it is on the left, then, accordingly, it is left-handed.

Such tools for a metal lathe also differ in the size of the holder (in mm):

16x10 (for small training machines);
20x12;
20x16 (the most common size);
40x25 (such massive turning cutters are difficult to find on the open market; they are mainly made to order).

Threading cutters for external threads

The purpose of such cutters for a metal lathe is to cut threads on the outer surface of the workpiece. These serial tools cut metric threads, but you can change their sharpening and use them to cut threads of other types.

The cutting plate installed on such turning tools has a spear-shaped shape and is made from the alloys mentioned above.

Such cutters are made in the following sizes (in mm):

16x10;
25x16;
32x20 (used very rarely).

Such cutters for a lathe can only cut threads in large-diameter holes, which is explained by their design features. Outwardly, they resemble boring cutters for processing blind holes, but they should not be confused, as they are fundamentally different from each other.

Such metal cutters are produced in the following standard sizes (in mm):

16x16x150;
20x20x200;
25x25x300.

The holder of these tools for a metal lathe has a square cross-section, the dimensions of the sides of which can be determined by the first two digits in the designation. The third number is the length of the holder. This parameter determines the depth to which a thread can be cut in the internal hole of a metal workpiece.

Such cutters can only be used on those lathes that are equipped with a device called a guitar.

Boring cutters for machining blind holes

Boring cutters, the cutting plate of which has a triangular shape (like scoring ones), are used to process blind holes. The working part of tools of this type is made with a bend.

The holders of such cutters can have the following dimensions (in mm):

16x16x170;
20x20x200;
25x25x300.

The maximum diameter of a hole that can be machined using such a turning tool depends on the size of its holder.

Boring cutters for machining through holes

Such cutters, the working part of which is made with a bend, process through holes, previously obtained by drilling. The depth of the hole that can be machined using a tool of this type depends on the length of its holder. The layer of metal that is removed is approximately equal to the bend of its working part.

The following standard sizes are available on the modern market, the requirements for which are specified in GOST 18882-73 (in mm):

16x16x170;
20x20x200;
25x25x300.

Prefabricated cutters for lathes

Considering the main types of turning tools, one cannot fail to mention tools with a prefabricated structure, which are considered universal, since they can be equipped with cutting inserts for various purposes. For example, by mounting cutting inserts of different types on one holder, you can obtain cutters for different angles.

To begin with, let's take into account that work on CNC machines is performed with general-purpose cutting tools (i.e., such a tool is used on machines that have manual control). But everything is not so simple, because if a tool is used on CNC machines, it must meet the following requirements: have high sharpening quality, be interchangeable, and must meet increased requirements for rigidity and wear resistance.

One type of cutting tool is a cutter. Thus, a turning cutter can perform many operations, including on CNC machines. And, of course, turning tools differ in purpose.

Therefore, the following subsystems were identified:

Turning cutters performing operations such as turning, threading, boring, grooving, cutting on medium and light series machines;

Turning cutters performing special work (for example, a shaped cutter or a cutter for plasma-mechanical processing);

Lathe cutters, which are installed on heavy, rotary and large machines;

Lathe cutters mounted on TBMs and multi-tasking machines.

Cutter subsystem for CNC machines.

Let's take a closer look at the cutter subsystem for CNC machines. For example, a cutter that has a modernized wedge fastening SMP - a wedge-clamp - is used to carry out preliminary and final operations on universal machines. The essence is to press the SMP with a wedge to the pin and to the support plate. Having such a fastening, we can observe an open auxiliary cutting edge.

Now, let's look at the subsystems of cutters that make up groove cutters and turning cutting cutters.

So, based on the structural features, the cutter can be:

1. Cut-off holder, in which replaceable non-sharpening carbide cutting inserts are mechanically fastened.

This cutter has in its structure: a spring-loaded clamp, a non-sharpening single-edge cutting plate, and a holder.

In order to install the cutting plate in the V-shaped groove of the holder socket, a V-shaped protrusion is required directly on the supporting surface of this very plate.

I would also like to note that if the cutting inserts are made of hard alloys with a wear-resistant coating, then the durability increases by 2-3 times.

2. Cutting, having soldered carbide plates.

Here they are already using new (including three-layer) brands of solders for manufacturing. And the holder can be made from steel 35KhGSA or 30KhGSA, which significantly reduces, or rather, practically eliminates cracking during soldering. Thus, the consumption of cutters is reduced by 3-4 times.

Very good quality and accuracy of sharpening leads to a reduction in the cost of primary sharpening (by about 0.3 - 0.4 rubles).

3. Groove holder, in which replaceable regrindable carbide cutting inserts are mechanically fastened.

From the name it is clear that such a cutter must be used to cut a groove (with exact dimensions). The cutting element is nothing more than a carbide plate made in accordance with GOST 2209-83. The structure of this cutter includes: a holder, a cutting plate (the shape of which is prismatic), a thrust element (which looks like a cracker), an adjusting screw and a clamp.

To prevent transverse displacements of the supporting surface of the cutting plate, it (the plate) is made at an angle to the side, and it is fixed with a clamp. The adjusting screw ensures that the cutting plate extends after regrinding, and subsequently fixes this same plate, thereby preventing longitudinal displacement.

The basis of this design served as the release of groove cutters, which allow the processing of internal threaded, angular, straight grooves and external angular and straight grooves.

Well, it’s worth noting that rational operation involves at least 20 resharpenings.

4. Cutting plate, having replaceable carbide cutting plates.

(But, such a cutter is primarily applicable for universal manually operated machines)

Such a cutter has in its structure: a block (which is fixed in the tool holder), a non-sharpening double-edge cutting plate, which is secured by an elastic blade of the holder, and a plate holder.

The cutter becomes more versatile because the plate holder allows you to adjust the indicators of its departure from the block to a given size.

5. Groove, in which replaceable non-regrindable carbide cutting inserts are mechanically fastened.

This type of cutter has in its structure: a holder, a clamping screw with a washer, and a double-edged cutting plate. The cutting plate is secured with a screw. As for the presence of two cutting edges, this allows you to save carbide.

Further, it is worth noting the subsystem of multi-purpose cutters, consisting of prefabricated cutters that allow roughing, semi-finishing and finishing turning of workpieces made of cast iron and steel.

Thus, workpieces can be turned, trimmed, processed, slotted, and bored.

The subsystem includes a small number of groups:

TTO

The cutter of this group is installed on heavy lathes (workpiece diameter 1250 - 4000 mm) and on rotary machines (workpiece diameter 3200 - 12000 mm), which have conventional tool holders.

Chamber of Commerce and Industry

The cutter of this group is installed on heavy lathes that have plate tool holders of CNC machines.

WHO

The cutter of this group is installed on large lathes (workpiece diameter 800 - 1000 mm), which have standard tool holders, and rotary machines (workpiece diameter 1600 - 2800 mm).

It is necessary to improve the quality of cutting tools in all possible ways, including, using the experience of inventors, developing new methods of fastening and changing plates, and using advanced technologies to increase labor productivity.

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Cutters for CNC machines

Introduction

Turning cutters are designed to perform a wide variety of different operations on CNC machines, on GPM and GPS, as well as on manually controlled turning machines.

Differences between turning tools by purpose.

According to their purpose, the system of turning cutters is divided into the following subsystems: cutter lathe sharpening

For external turning, boring, threading, cutting grooves and cutting off on light and medium series machines;

For work on heavy, large lathes and rotary machines;

For work on GPM, multi-purpose machines with built-in robotic complexes for automatic tool changing;

For special work (cutters for plasma-mechanical processing, shaped).

Each of the subsystems has its own specific features, determined by many factors, primarily the design of the equipment, its technological purpose, etc. The cutter system is based on general methodological principles and provides for:

Development (selection) and unification of reliable methods for fastening replaceable plates in a holder (including solid and composite cutters, with soldered plates, prefabricated ones);

Ensuring satisfactory crushing and removal of chips from the cutting zone;

Sufficiently high positioning accuracy of the vertices of the replaceable plates (due to the creation of precise bases of the socket);

Quick change and ease of removal and replacement of replaceable plates, cutting element or cassette (block);

Unification and maximum permissible reduction (reduction to the optimal value of technical and economic indicators of industrial production and application) of the number of methods for securing plates in the holder;

Possibility of using the entire range and sizes of replacement plates of domestic and foreign production;

Compliance of precision parameters of cutters with international standards;

Mandatory use of special fasteners (screws, pins, etc.) of increased accuracy and reliability; development of new shapes and sizes of cutting inserts, shapes of their front surfaces, ensuring satisfactory crushing and removal of chips;

Using the experience of innovators and inventors;

Application of progressive resource-saving technologies for the manufacture of fasteners and keys; manufacturability and cost-effectiveness of manufacturing (saving materials and labor resources);

The possibility of using composite (found, solid, glued and other similar connections) carbide inserts with tool blocks (holders) in cases of their undoubted technical and economic efficiency or the impossibility of designing a cutter in a prefabricated version (primarily for small sections of holders, some boring and cutting operations, etc.).

The cutter design subsystems are created on the basis of a generally accepted world practice system of toolholder shapes and plan angles to ensure all turning operations. For example, for the subsystem of external turning and boring of the shape of holders, which ensures the implementation of the entire variety of turning transitions, international (ISO 5910, 5909, etc.) and domestic standards are provided.

1. Basic cutter patterns

Currently, despite the huge variety of designs and patterns of fastening units for replaceable polyhedral plates in holders, leading foreign manufacturers of cutters use a very limited number of fastening methods in mass production. Their number is also limited in domestic cutter subsystems. For example, in subsystems for external turning and boring on machines of light and medium series, four basic design schemes for SMP fastening units are adopted (designation of fastenings according to GOST 26476-85):

Without hole - clamp (type C);

With a cylindrical hole - lever mechanism (type P);

Pin and clamp (type M);

With toroidal hole - screw mechanism (type S).

Plates without holes are fixed using method C. The design is based on a design widely used in automobile factories. With this method of fastening, the cutting inserts are based in a closed holder socket along two base surfaces and pressed from above to the supporting surface with a clamp. Quick plate removal is ensured by a differential screw. The carbide support plate is secured with a screw to the cutter holder or a split spring bushing.

Cutters with SMP fastening according to method C have different designs: for cutting inserts with a clearance angle and without a clearance angle; with support plates; without support plates.

It should be noted that the relief angle SMPs have 2 times more cutting edges than the relief angle SMPs. On the front surface of the SMP with a rear angle there are chip-breaking grooves for crushing and removing drain chips. When using SMP without a clearance angle, overhead chipbreakers are used.

Cutters with a base plate are widely used for turning and boring; cutters without a support plate - when boring small holes and turning on light series machines (section h [ b cutter holder 12 x 12...16 x 16 mm). The operation of the cutters has shown that cutters with carbide chipbreakers have proven themselves well when working on universal and special machines in large-scale and mass production.

In such cutters, you can use SMP made of hard alloy, ceramics, etc.

Cutters with SMP with positive angles provide a reduction in cutting forces, so they are recommended for use when processing non-rigid parts. These cutters can also be used with overhead chipbreakers. For external turning and boring in cutters with clamping according to method C, square, triangular, rhombic SMPs are used, as well as parallelogram plates of the KNUX type with fastening with a special shaped clamp. SMP with a central cylindrical hole is secured with a lever mechanism using the P method and a modernized wedge fastening (wedge-interception) using the M method. Fastening with a lever mechanism is the most rational for cutters with a holder section from 20 x 20 to 40 x 40 mm. This design is effectively used on CNC machines. A domestic original design of the lever mechanism has been developed, which corresponds to the best world standards, and in terms of purpose is completely unified with the designs of cutters produced at some large machine-building plants of the domestic industry, and with tools produced abroad.

The design of the fastening unit provides the ability to quickly and accurately rotate or change the SMP and securely fasten it. It allows the whole range of new progressive domestic and foreign inserts, as well as SMP with a complex front surface shape, which ensures good chip crushing in a wide range of feeds and cutting depths.

For contour processing on machines with CNC, GPM and GPS, which allows turning several surfaces of a part in one working stroke, cutters with rhombic SMP ((=80(and 55()) are used. Industrial batches of cutters with an L-shaped lever for external turning and wide boring They have been mastered in mass production by tool factories of the Ministry of Stank Industry, they are produced according to TU2-035-892 and GOST 26613-85.

2. Cutter subsystem for CNC machines

To perform preliminary and final operations with one cutter, primarily on universal manually controlled machines, a range of cutters with a modernized wedge fastening with an SMP wedge-clamp (method M) has been developed. The wedge presses the SMP not only to the pin on which it is installed with the central hole, but also to the support plate. With this fastening of the SMP, the auxiliary cutting edge remains open. A subsystem of turning cutting and grooving cutters for CNC and GPM machines has also been developed, which includes the following cutters:1. High-reliability cutting tools with brazed carbide inserts. They are distinguished from cutting tools produced in accordance with GOST 18884-73 by:

Increased manufacturing accuracy and relative position of holder surfaces, which ensures their use on CNC machines;

The use of new, including three-layer, grades of solders and the replacement of the holder material with steel 35KhGSA or 30KhGSA virtually eliminates cracking during soldering, which will reduce the consumption of cutters by approximately 3-4 times;

Increased quality and accuracy of cutter sharpening reduces consumer costs for primary sharpening by 0.3-0.4 rubles;

Improved appearance.

The main dimensional parameters of the cutters fully comply with the ISO243-1975 (E) standard.

2. Holder cutting cutters with mechanical fastening of replaceable non-sharpening carbide cutting inserts.

The cutter consists of a holder, a non-sharpening single-edge cutting plate, and a spring-loaded clamp. There is a V-shaped protrusion on the supporting surface of the cutting insert, with which it is installed in the V-shaped groove of the holder seat. When fastening, the cutting plate is pressed against the side of the socket's thrust surface. The geometric parameters of the cutting part ensure good removal of chips from the cutting zone, which is especially important when processing workpieces made of viscous materials.

The use of cutting inserts made of hard alloys with a wear-resistant coating ensures an increase in durability by 2-4 times.

3. Cutting-off plate cutters with mechanical fastening of replaceable non-resharpening carbide cutting inserts are designed to perform cutting operations primarily on manually operated universal machines. The cutter consists of a block fixed in the tool holder of the machine, a plate holder and a non-sharpening double-edged cutting plate, which is secured by an elastic blade of the holder. The supporting surfaces of the cutting plate are made in the form of V-shaped grooves, with which it interacts with the V-shaped protrusions of the socket and the elastic lobe of the holder.

Reducing the width of one of the two cutting edges by 0.3-0.4 mm ensures the performance of each cutting edge within the standard average service life, but for this, the worn out edge must be sharpened by 0.3-0.4 mm. This technical solution saves carbide.

The plate holder allows you to adjust the value of its protrusion from the block to the required size, which makes the cutter more versatile. The shape of the front surface of the cutting inserts ensures satisfactory chip formation and good chip removal when processing workpieces made of various steels in a wide feed range.

4. Groove holder cutters with mechanical fastening of replaceable regrindable carbide cutting inserts are designed for use on universal and CNC machines. They are used primarily for cutting grooves of precise dimensions. Carbide inserts produced in accordance with GOST 2209-83 are used as the cutting element.

The outer shape of the cutting part and the required size are ensured by sharpening. The maximum cutting edge width is 4.8 mm. The cutter consists of a holder, a prismatic cutting plate, a clamp and a thrust element in the form of a block and an adjusting screw. The supporting surface of the cutting plate is made at an angle to the side, which ensures its fixation from transverse displacements when secured with a clamp. The projection of the cutting plate after regrinding and its fixation from longitudinal displacement is ensured by an adjusting screw.

On the basis of this design, groove cutters for processing external straight and angular grooves have been mastered and are being mass-produced; for machining internal straight, angular and threaded grooves. With rational operation, the permissible number of resharpenings is at least 20.

5. Grooving cutters with mechanical fastening of replaceable non-regrindable carbide cutting inserts consist of a holder, a double-edge cutting insert and a clamping screw with a washer. The supporting surfaces of the cutting plate are made in the form of V-shaped grooves, with which it interacts with the V-shaped protrusions of the socket. The cutting plate is secured with a screw that interacts with the upper part of the socket formed by a slot in the holder.

Accuracy of positioning and fixation of the cutting plate from longitudinal displacement is ensured by the presence of a thrust base surface in the socket.

The ratio of the depth of the cut groove to its width is in the range from 1.0 to 2.0, depending on the width of the cutting part.

The presence of two cutting edges on the cutting plate ensures savings in carbide. The shape of the rake surface of the cutting inserts ensures satisfactory chip formation and good chip removal over a wide feed range.

The presented range of cutters provides the ability to perform all types of cutting and grooving operations.

To cut threads on lathes, cutters with soldered carbide plates are used in accordance with GOST 18885-73, with mechanical fastening of the carbide plates.

The design of the cutter with mechanical fastening of the sharpened plates is similar to the design of the grooving cutter for cutting straight grooves, the only difference is in the sharpening of the cutting plate with a profile angle at the apex equal to 59 (30). With the accepted width of the plate used, a cut thread pitch of 0.8 to 3.5 mm is ensured. Precise grinding (sharpening) of the profile of the cutting part ensures the production of cut threads with an average degree of accuracy.

In cutters with mechanical fastening of a non-regrindable rhombic cutting plate, the required geometry of the cutting part of the plate is ensured by pressing and sintering. For reliable fastening of the cutting plate in the blind socket of the holder, there is a V-shaped groove on its front surface, intended for connection with the clamp. The pitch of the cut threads ranges from 2.5 to 6.0 mm.

Special profile threads on pipes, couplings, nipples and locks of oil and geological exploration equipment, depending on the thread profile, are cut with the following cutters:

Preliminary - cutters equipped with a triangular-shaped SMP in accordance with GOST 19043-80 and GOST 19044-80;

The final one is cutters equipped with square or triangular plates with a cutting part, the profile of which is obtained by grinding.

Plates without a hole are fixed using method C, and plates with a hole

Pulling grip. The profile of the cutting part can be multi-toothed (up to five) on one cutting edge; The pitch range of cut threads is from 2.54 to 6.35 mm. The number of working strokes, depending on the step, is from 2 to 12.

Let's consider a subsystem of broad-purpose cutters for processing on heavy and large lathes, rotary lathes and roll lathes, including CNC machines. Such cutters can also be used for other heavy metal-cutting equipment. The subsystem includes prefabricated cutters for rough, semi-finishing and finishing turning of workpieces made of steel, cast iron and other materials of any hardness with a cutting depth for roughing up to 50 mm and a feed rate of up to 10 mm/rev. Cutters are used for turning, trimming, boring large diameters, cutting and cutting, and processing transition surfaces.

The subsystem consists of several groups:

TTO - for heavy lathes with the largest diameter of the installed workpiece 1250-4000 mm and for rotary machines with the largest diameter of the installed workpiece 3200-12000 mm, having conventional tool holders;

TTP - for heavy lathes with plate tool holders of CNC machines;

KTO - for large lathes with the largest diameter of the installed workpiece 800-1000 mm, having standard turning tool holders, and rotary machines with the largest diameter of the installed workpiece 1600-2800 mm.

The TTO group provides two types of cutter up to its supporting surface.

A set of quick-change blocks B1 (right and left pass-through, drive-through thrust, scoring, etc.) is fixed to the main body of K1. These blocks are designed for machining with large cutting depths (t= 12...40 mm), including roughing and intermittent cutting. The auxiliary body K2 is designed for fastening cutters of the KTO group (t=10...20 mm), as well as standard ones (t(8 mm).

The TTP group has three types of L-shaped tool bodies of different widths for plate tool holders, which provide minimal cutter head overhang and high rigidity of the support with tool holder. On the K4 body, B1 blocks are attached for large cutting depths, on the K5 body - cutters of the KTO group for medium cutting depths, and on the K6 body - B blocks for small cutting depths.

Various joints of bodies, blocks, cutters and plates make it possible to obtain, just for part of the subsystem, more than 200 types of tools for various transitions with different main angles in the plan and lengths l of blades.

In the developed subsystem, for particularly severe cutting conditions, plates with a P1 shoulder are used (TU 48-19-373-83). The inserts are characterized by a slight increase in thickness with a corresponding decrease in width, which leads to a further increase in the strength of the tool.

The use of cutters with plates with a shoulder, with their rational fastening and basing, provides an increase in feed rate by 20-40% compared to the feed rate when processing with cutters with a brazed plate (which is 10-15% higher compared to the best prefabricated cutters from foreign companies).

For semi-finish machining with smaller cutting depths, a thickened polyhedral plate P3 with a hole is used. The new design of the fastening unit ensures reliable clamping of this plate to the supporting and thrust surfaces.

3. Tool materials

Cutting tools are made entirely or partially from tool steels and hard alloys.

Tool steels are divided into carbon, alloy and high-speed. Carbon tool steels are used for the manufacture of tools operating at low cutting speeds. Knives, scissors, saws are made from carbon steel grades U9 and U10A, and metalworking taps, files, etc. are made from U11, U11F, U12. The letter U in the steel grade means that the steel is carbon, the number after the letter indicates the carbon content in the steel in tenths fractions of a percent, and the letter A means that the steel is high-quality carbon steel, since it contains no more than 0.03% of sulfur and phosphorus each.

The main properties of these steels are high hardness (HRC 62-65) and low heat resistance. Heat resistance refers to the temperature at which the tool material retains high hardness (HRC 60) when subjected to repeated heating. For steels U10A - U13A, the heat resistance is 220 (C), therefore the recommended cutting speed with a tool made from these steels should be no more than 8-10 m/min.

Alloyed tool steels are chromium (X), chromium-silicon (XS) and chrome-tungsten-manganese (HVG), etc.

The numbers in the steel grade indicate the composition (in percentage) of the incoming components. The first number to the left of the letter determines the carbon content in tenths of a percent. The numbers to the right of the letter indicate the average content of the alloying element as a percentage. If the alloying element or carbon content is close to 1%, the figure is not given.

Taps, dies, and cutters are made from grade X steel; made of steel 9ХС, ХГС

Drills, reamers, taps and dies; made of steel ХВ4, ХВ5 - drills, taps, reamers; made of HVG steel - long taps and reamers, dies, shaped cutters.

The heat resistance of alloy tool steels reaches 250-260 (C and therefore the permissible cutting speeds for them are 1.2-1.5 times higher than for carbon steels.

High-speed (high-alloy) steels are used for the manufacture of various tools, but most often drills, countersinks, and taps.

High-speed steels are designated by letters and numbers, for example P9, P6M3, etc. The first P (rapid) means that the steel is high-speed. The numbers after it indicate the average tungsten content as a percentage. The remaining letters and numbers mean the same as in alloy steel grades.

These groups of high-speed steels differ in properties and areas of application. Normal performance steels, having hardness up to HRC65, heat resistance up to 620 (C and bending strength 3000-4000 MPa, are intended for processing carbon and low-alloy steels with tensile strength up to 1000 MPa, gray cast iron and non-ferrous metals. Normal performance steels include tungsten grades R18, R12, R9, R9F5 and tungsten-molybdenum grades R6M3, R6M5, maintaining a hardness of at least HRC 62 up to a temperature of 620.

High-performance high-speed steels, alloyed with cobalt or vanadium, with a hardness of up to YRC 73-70 with a heat resistance of 730-650 (C and with a bending strength of 250-280 MPa are intended for processing difficult-to-cut steels and alloys with a tensile strength of over 1000 MPa, titanium alloys and etc. Improving the cutting properties of steel is achieved by increasing the carbon content in it from 0.8 to 1%, as well as additional alloying with zirconium, nitrogen, vanadium, silicon and other elements.High-speed steels with increased productivity include 10R6M5K5, R2M6F2K8AE, R18F2, R14F4, R6M5K5 , R9M4EV, R9K5, R9K10, R10K5F5, R18K5F2, maintaining hardness HRC 64 up to a temperature of 630-640.

Hard alloys are divided into metal-ceramic and mineral-ceramic; they are produced in the form of plates of various shapes. Tools equipped with carbide inserts allow higher cutting speeds than high-speed steel tools.

Metal-ceramic hard alloys are divided into tungsten, titanium-tungsten, and titanium-tantalum-tungsten.

Tungsten alloys of the VK group consist of tungsten and cobalt carbides. Alloys of grades VK3, VK3M, VK4, VK6, VK60M, VK8, VK10M are used. The letter B stands for tungsten carbide, K stands for cobalt, and the number stands for the percentage of cobalt (the rest is tungsten carbide). The letter M at the end of some grades indicates that the alloy is fine-grained. This alloy structure increases the wear resistance of the tool, but reduces impact resistance. Tungsten alloys are used for processing cast iron, non-ferrous metals and their alloys and non-metallic materials (rubber, plastic, fiber, glass, etc.).

Titanium-tungsten alloys of the TK group consist of tungsten, titanium and cobalt carbides. This group includes alloys of the T5K10, T5K12, T14K8, T15K6, T30K4 brands. The letter T and its number indicate the percentage of titanium carbide, the letter K and the number behind it indicate the percentage of cobalt carbide, the rest in this alloy is tungsten carbide. These alloys are used for processing all types of steels.

Titanium tantalum tungsten alloys of the TTK group consist of tungsten, titanium, tantalum and cobalt carbides. This group includes alloys of the TT7K12 and TT10KV-B brands, containing 7 and 10% titanium and tantalum carbides, 12 and 8% cobalt, respectively, and the rest is tungsten carbide. These alloys work in particularly difficult processing conditions, when the use of other tool materials is not effective.

Alloys with a lower percentage of cobalt, grades VK3, VK4, have lower viscosity; used for processing with the removal of thin chips during finishing operations. Alloys with a higher cobalt content of grades VK8, T14K8, T5K10 have higher viscosity, they are used for processing with the removal of thick chips in roughing operations.

Fine-grained hard alloys of the VK3M, VK6M, VK10M grades and coarse-grained alloys of the VK4 and T5K12 grades are used under conditions of pulsating loads and when processing difficult-to-cut stainless, heat-resistant and titanium alloys.

Hard alloys have high heat resistance. Tungsten and titanium-tungsten carbide alloys retain hardness at a temperature in the processing zone of 800-950 (C), which allows working at high cutting speeds (up to 500 m/min when processing steels and 2700 m/min when processing aluminum).

Especially fine-grained tungsten-cobalt alloys of the OM group are intended for processing parts made of stainless, heat-resistant and other difficult-to-machine steels and alloys: VK60OM - for finishing processing, and VK10-OM and VK15-OM alloys - for semi-finishing and rough processing. Further development and improvement of alloys for processing difficult-to-machine materials caused the appearance of alloys of the VK10-KHOM and VK15-KHOM brands, in which tantalum carbide was replaced by chromium carbide. Alloying alloys with chromium carbide increases their hardness and strength at elevated temperatures.

To increase the strength of hard alloy plates, cladding them with protective films is used. Wear-resistant coatings made of titanium carbides applied to the surface of carbide in the form of a thin layer 5-10 mm thick are widely used. In this case, a fine-grained layer of titanium carbide is formed on the surface of the carbide plates, which has high hardness, wear resistance and chemical resistance at high temperatures. The durability of coated carbide inserts is on average 1.5-3 times higher than the durability of conventional inserts, and the cutting speed can be increased by 25-80%. Under severe cutting conditions, where conventional inserts exhibit chipping and chipping, the effectiveness of coated inserts is reduced.

The industry has mastered economical tungsten-free hard alloys based on titanium and niobium carbide, titanium carbonitrides on a nickel-molybdenum binder. Tungsten-free hard alloys of the TM1, TM3, TN-20, TN-30, KNT-16 brands are used. They have high scale resistance, exceeding the resistance of alloys based on titanium carbide (T15K6, T15K10) by more than 5-10 times. When processed at high cutting speeds, a thin oxide film is formed on the surface of the alloy, which acts as a solid lubricant, which increases wear resistance and reduces the roughness of the machined surface. At the same time, tungsten-free hard alloys have lower impact strength and thermal conductivity, as well as resistance to impact loads, than alloys of the TK group. This allows them to be used in finishing and semi-finishing machining of structural and low-alloy steels and non-ferrous metals.

From mineral-ceramic materials, the main part of which is aluminum oxide with the addition of relatively rare elements: tungsten, titanium, tantalum and cobalt, oxide (white) ceramics of the TsM-332, VO13 and VSh-75 brands are common. It is characterized by high heat resistance (up to 1200 (C)) and wear resistance, which allows processing metal at high cutting speeds (for finishing turning of cast iron - up to 3700 m/min), which are 2 times higher than for hard alloys. Currently for manufacturing cutting tools use cutting (black) ceramics grades B3, VOK-60, VOK-63, VOK-71.

Cutting ceramics (cermet) is an oxide-carbide compound of aluminum oxides and 30-40% tungsten and molybdenum or molybdenum and chromium carbides and refractory binders. The introduction of metals or metal carbides into the composition of mineral ceramics improves its physical and mechanical properties and also reduces fragility. This allows you to increase processing productivity by increasing cutting speed. Semi-finishing and finishing machining of parts made of gray, malleable cast iron, difficult-to-cut steels, and some non-ferrous metal alloys is carried out at a cutting speed of 435-1000 m/min without cutting fluid. Cutting ceramics are highly heat resistant.

Oxide-nitride ceramics consists of silicon nitrides and refractory materials with the inclusion of aluminum oxide and other components (silinite-R and cortinite ONT-20).

Silinit-R is not inferior in strength to oxide-carbide mineral ceramics, but has greater hardness (HRA 94-96) and stable properties at high temperatures.

Hardened and cemented steels (HRC 40-67), high-strength cast irons, hard alloys such as VK25 and VK15, fiberglass and other materials are processed with a tool whose cutting part is made of large polycrystals with a diameter of 3-6 mm and a length of 4-5 mm based on cubic nitride boron (elbor-R, cubonite-R, hexanite-R). In terms of hardness, CBN-R is close to diamond (86,000 MPa), and its heat resistance is 2 times higher than the heat resistance of diamond. Elbor-R is chemically inert to iron-based materials. The compressive strength of polycrystals reaches 4000-5000 MPa, flexural strength 700 MPa, heat resistance - 1350-1450 (C. Abrasive materials include normal electrocorundum grades 14A, 15A and 16A, white electrocorundum grades 23A, 24A and 25A, monocorundum grades 43A, 44A and 45 A. Green silicon carbide grades 63C and 64C and black grades 53C and 54C, boron carbide, CBN, synthetic diamond, etc.

Powders are made from abrasive materials, which are intended for cutting in a free and bound state in the form of abrasive tools (grinding wheels, whetstones, sandpapers, tapes, etc.) and pastes.

4. Sharpening cutters

At machine-building enterprises, tools are usually sharpened centrally. However, sometimes it is necessary to sharpen the tool by hand.

For manual sharpening of tools, sharpening and grinding machines are used, for example a machine model 3B633, consisting of a grinding head and a bed. A two-speed electric motor is built into the grinding head. Grinding wheels are attached to the outgoing ends of the rotor shaft and are covered with casings with protective screens. The machine is equipped with a rotary table or a tool rest for installing the cutter. The frame houses the electrical cabinet and control panel.

Grinding and grinding machines, depending on the purpose and size of the grinding wheels, can be divided into three groups: small machines with a wheel with a diameter of 100-175 mm for sharpening small tools, medium machines with a wheel with a diameter of 200-350 mm for sharpening the main types of cutters and other tools, large machines with a circle with a diameter of 400 mm or more for grinding parts and roughing and cleaning work.

Cutters, depending on their design and wear pattern, are sharpened along the front, back or both surfaces. Standard cutters with carbide or high-speed steel inserts are most often sharpened along all cutting surfaces. In some cases, if the cutters have slight wear on the front surface, they are sharpened only on the back surface.

When sharpening on sharpening and grinding machines, the cutter is placed on a rotary table or tool rest and the surface being processed is manually pressed against the grinding wheel. To wear the wheel evenly, the cutter must be moved along a table or tool rest relative to the working surface of the wheel.

When sharpening a cutter along the back surfaces, the table or tool rest is turned to a given back angle and secured in close proximity to the wheel. The cutter is placed on a table or tool rest so that the cutting edge is parallel to the working surface of the circle. The front surface of the cutter is most often sharpened with the side surface of the circle, while the cutter is mounted on the tool rest of the side surface. The front surface can also be sharpened using the periphery of a circle, but this method is less convenient. High-speed steel cutters are sharpened first along the front, then along the main and auxiliary rear surfaces. When sharpening carbide cutters, the same procedure is used, but the rear surfaces of the rod are pre-processed at an angle 2-3 greater than the sharpening angle on the carbide plate.

The quality of sharpening depends on the qualifications of the worker doing the sharpening and the characteristics of the grinding wheels. As the force of pressing the tool against the grinding wheel increases, labor productivity increases, but at the same time burns and cracks may occur. Typically, the clamping force does not exceed 20-30 N. With increasing longitudinal feed, the likelihood of crack formation decreases.

Typically, grinding wheels of different characteristics are installed on a sharpening and grinding machine, which allows for preliminary and final sharpening of the tool. When pre-sharpening carbide tools, use wheels made of carbide, silicon (24A) with grain size 40, 25, 16 and hardness CM2 and C1 on a ceramic bond (K5); final sharpening (with an allowance of 0.1-0.3 mm) is performed on diamond, CBN and fine-grained abrasive wheels with a bakelite bond.

When pre-sharpening high-speed tools, grinding wheels made of electrocorundum (23A, 24A) with a grain size of 40, 25, 16 and hardness CM1, CM2 on a ceramic bond (K5) are used. The final sharpening (with an allowance of 0.1-0.3 mm) is performed with wheels made of electrocorundum (23A, 24A) or monocorundum (43A, 45A) with a grain size of 25, 16 and 12 and a hardness of M3, SM1, SM2 in a non-ceramic bond (K5). The surface roughness of the tool after preliminary sharpening is 2.5-0.63 microns, after final sharpening it is 0.63-0.1 mm according to Ra.

When sharpening a cutter on a fine-grained wheel, irregularities remain on the cutting edge, which directly affect the wear rate of the cutter. Therefore, after sharpening, the cutter is polished on a diamond wheel or on rotating cast iron discs using abrasive pastes. The rotation speed of the diamond wheel is up to 25 m/s, the disk rotation speed is 1-1.5 m/s. The cutter is adjusted along the main back and front surfaces to a chamfer of 1.5-4 mm. The auxiliary back surface of the cutter is not processed.

To obtain high-quality surfaces (Ra = 0.32 (0.08 microns), it is necessary that the runout of the finishing disk or circle does not exceed 0.05 mm, and their rotation must be directed under the cutting edge. Before applying the paste to the disk, it should be lightly wipe with a felt brush dipped in kerosene. The layer of paste applied to the disk should be thin, since a thick layer does not speed up the finishing process. Finishing should be done with light pressure, touching the finishing disk with the cutter without hitting. Strong pressure does not speed up the finishing, but only increases paste consumption and accelerates disc wear.

Checking the sharpening angles of the cutter can be done using templates and instruments.

Drills are sharpened along the back surface, giving it a curved shape to ensure equal back angles in any section of the cutting teeth. To do this, the drill is pressed against the grinding wheel and rotated at the same time. First, sharpen the surface near the cutting edge, and then the surface located at a large rear angle. For carbide drills, the plate is sharpened first, and then the drill body.

Bibliography

1. V.N.Feshchenko, Makhmutov R.Kh. Turning. Publishing house "Higher School". Moscow. 1990.

2. L. Fadyushin, Ya. A. Muzykant, A. I. Meshcheryakov and others. Tools for CNC machines, multi-purpose machines. M.: Mechanical Engineering, 1990.

3. P.I.Yashcheritsyn et al. Fundamentals of cutting materials and cutting tools. Mn.: Higher school, 1981.

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Cutters for turning on CNC machines.

Turning cutters are designed to perform a wide variety of different operations on CNC machines, on GPM and GPS, as well as on manually controlled turning machines.

Differences between turning tools by purpose.

According to their purpose, the turning tool system is divided into the following subsystems:

· for external turning, boring, threading, cutting grooves on light and medium series machines;

· for work on heavy, large lathes and rotary machines;

· for work on GPM, multi-purpose machines with built-in robotic complexes for automatic tool changing;

· for special work (cutters for plasma-mechanical processing, shaped).

· development (selection) and unification of reliable methods for fastening replaceable plates in the holder (including solid and composite cutters, with soldered plates, prefabricated ones);

· ensuring satisfactory crushing and removal of chips from the cutting zone;

· sufficiently high positioning accuracy of the vertices of the replaceable plates (due to the creation of precise bases of the socket);

· quick change and ease of removal and replacement of replaceable plates, cutting element or cassette (block);

· unification and maximum permissible reduction (reduction to the optimal value of technical and economic indicators of industrial production and application) of the number of methods for securing plates in the holder;

· the ability to use the entire range and sizes of replacement plates of domestic and foreign production;

· compliance of the precision parameters of the cutters with international standards;

· mandatory use of special fasteners (screws, pins, etc.) of increased accuracy and reliability; development of new shapes and sizes of cutting inserts, shapes of their front surfaces, ensuring satisfactory crushing and removal of chips;

· using the experience of innovators and inventors;

· application of progressive resource-saving technologies for the manufacture of fasteners and keys; manufacturability and cost-effectiveness of manufacturing (saving materials and labor resources);

· the possibility of using composite (found, solid, glued and other similar connections) carbide inserts with tool blocks (holders) in cases of their undoubted technical and economic efficiency or the impossibility of designing a cutter in a prefabricated version (primarily for small sections of holders, some boring and cutting operations, etc.).

Basic cutter patterns.

· without hole – with clamp (type C);

· with a cylindrical hole – lever mechanism (type P);

· pin and clamp (type M);

· with a toroidal hole – screw mechanism (type S).

Cutters with SMP fastening according to method C have different designs: for cutting inserts with a clearance angle and without a clearance angle; with support plates; without support plates.

In such cutters, you can use SMP made of hard alloy, ceramics, etc.

For external turning and boring in cutters with clamping according to method C, square, triangular, rhombic SMPs are used, as well as parallelogram plates of the KNUX type with fastening with a special shaped clamp. SMP with a central cylindrical hole is secured with a lever mechanism using the P method and a modernized wedge fastening (wedge-interception) using the M method. Fastening with a lever mechanism is the most rational for cutters with a holder section from 20 x 20 to 40 x 40 mm. This design is effectively used on CNC machines. A domestic original design of the lever mechanism has been developed, which corresponds to the best world standards, and in terms of purpose is completely unified with the designs of cutters produced at some large machine-building plants of the domestic industry, and with tools produced abroad.

The SMP is based in a closed socket of the holder, and a lever driven by a screw pulls it to the two side walls of the socket and presses it securely against the support. The support plate is secured with a split sleeve. The design of the fastening unit provides the ability to quickly and accurately rotate or change the SMP and securely fasten it. It allows the whole range of new progressive domestic and foreign inserts, as well as SMP with a complex front surface shape, which ensures good chip crushing in a wide range of feeds and cutting depths.

For contour processing on machines with CNC, GPM and GPS, which allows turning several surfaces of a part in one working stroke, cutters with rhombic SMP (e = 80° and 55°) are used. Industrial batches of cutters with an L-shaped lever for external turning and boring are widely used in mass production by tool factories of the Ministry of Machine Tools and Industry; they are produced in accordance with TU2-035-892 and GOST 26613-85.

Cutter subsystem for CNC machines.

A subsystem of turning cutting and grooving cutters for CNC and GPM machines has also been developed, which includes the following cutters.

1. High-reliability cutting tools with brazed carbide inserts. They are distinguished from cutting tools produced in accordance with GOST 18884-73 by:

· increased manufacturing accuracy and relative position of holder surfaces, which ensures their use on CNC machines;

· the use of new, including three-layer, grades of solders and the replacement of the holder material with steel 35KhGSA or 30KhGSA virtually eliminates cracking during soldering, which will reduce the consumption of cutters by approximately 3-4 times;

· increased quality and accuracy of cutter sharpening reduces consumer costs for primary sharpening by 0.3-0.4 rubles;

· improved appearance.

The main dimensional parameters of the cutters fully comply with the ISO243-1975 (E) standard.

2. Holder cutting cutters with mechanical fastening of replaceable non-sharpening carbide cutting inserts.

The use of cutting inserts made of hard alloys with a wear-resistant coating ensures an increase in durability by 2-4 times.

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Cutters for a CNC machine. Classification of cutters for a metal lathe - types, purpose

Lathe cutter design

Classification of cutters for turning

Prefabricated cutters for lathes

Cutter subsystem for CNC machines.

1. Cut-off holder, in which replaceable non-sharpening carbide cutting inserts are mechanically fastened.

2. Cutting, having soldered carbide plates.

3. Groove holder, in which replaceable regrindable carbide cutting inserts are mechanically fastened.

4. Cutting plate, having replaceable carbide cutting plates.

5. Groove, in which replaceable non-regrindable carbide cutting inserts are mechanically fastened.

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Cutters for CNC machines

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Cutters for turning on CNC machines.

Differences between turning tools by purpose.

Basic cutter patterns.

Cutter subsystem for CNC machines.

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