Cutter for a metal lathe, what are they: types (types), marking, designation

Design features of turning tools

Each turning tool consists of two parts.

1. Holder. Can be square or rectangular. With its help, the cutter is secured in the mounting sockets of the machines. GOST establishes the following standard dimensions of holders. Square - 4*4, 6*6, 8*8, 10*10, 12*12, 16*16, 20*20, 25*25, 32*32, 40*40 mm.
2. Rectangular - 16*10, 20*12, 25*16, 25*20, 50*25, 40*32, 50*32, 50*40, 63*50 mm.

Image #1: Lathe cutter design

Cutting planes

The angular parameters of a cutting turning tool are calculated using a system of coordinate planes, among which the basic planes are the main plane, the cutting plane and the main secant plane. Their mutual inclination forms the sharpening angles of the cutting part, ensuring turning in design modes. In this way, the following angles are determined: the main front (γ), the main back (α), the sharpening angle (β), as well as a number of other angles.

Cutter angles

The operation of a turning tool during the cutting process is determined by the angular parameters of the front and rear surfaces. Therefore, the main angles of the incisor are the main anterior (γ) and the main rear (α). By increasing the first, power consumption for cutting is reduced, chip control is improved and roughness is reduced. On the other hand, as the rake angle increases, the thickness of the blade decreases, which leads to a deterioration in its strength characteristics, increased chipping and a decrease in the rate of heat dissipation. The main purpose of the clearance angle is to reduce friction between the cutting surface and the main clearance. In addition to the main functional angles α and γ, the calculation determines several more angles, whose values ​​affect the class of turning cleanliness, the process of chip formation and other technical characteristics.

Depending on the purpose

Here we are most often talking about the materials being processed.

For wood

Woodworking tools are sold by stores in the following sets:

• Combs.
• Rings.
• Hooks.
• Oblique incisors.
• Trimming cutters.
• Chisels.
• Reiers.
• Meysel.

The cutters and rotary mechanisms are attached to each other. Traces of workpieces are determined immediately by the tools, their shapes, strength, and sharpness. This makes it easier to select the shapes of the blanks in the end. From

When choosing specific sharpening angles, they rely on the materials of the workpieces.

For working with metal

Welding and brazing of plates is the optimal choice for cutters that process metal. In production, preference is given to high-speed, hard alloys. The compositions usually contain tantalum or tungsten, titanium. High strength and affordable price have become the main advantage for the tools.

Varieties are often used in which the plates are replaceable. Then they are attached to the head using special screws or clamping elements. Mineral ceramic plates are the most convenient for further use. But then the cutter will be expensive.

Carbide alloys are used in the case of tool working surfaces:

1. Tungsten.
2. Titanium tungsten.
3. Tantalum-tungsten-titanium.

Options with high-speed steel or its carbon variety are acceptable.

Installation of cutters is permissible on several types of machines:

• Special purpose.
• Revolving automatic.
• Slotting.
• Lathes.
• Planing.

By type of processing

Finishing

Feed at low speed. The material, which is characterized by a small thickness, is removed from the blank. A pass-through cutter is the most popular type of such tool.

Semi-finish

Many similarities with the previous variety. Only the characteristics they use are two times smaller compared to the analogue. The purpose and features of the work remain almost the same.

What are the types of incisors?

Mechanical cutting of external cylindrical/conical surfaces involves the use of one of the following types of tools:

• straight cutter;
• bent;
• stubborn.

The straight cutter is used for turning materials not only on turning machines, but also on slotting and planing units. This product is made from high-speed steel (according to GOST 18868-73) or equipped with carbide brazing, which is subsequently adjacent to a metal frame (GOST 18879-73). If tool production is based on the first method, then the cutter can be used for structures that work with heated and unalloyed workpieces. Carbide materials are more designed for finishing dense types of metal.

The size range of straight cutting products of the through type is quite wide. But there are cutters whose parameters are in greatest demand among turners.

The cross-section of the body of the through cutter can have the shape of a square or rectangle. Bent cutting tools are used in practice more often than straight ones, since they provide universal capabilities in work. They have greater rigidity and, due to their shape, make it possible to grind parts even in hard-to-reach areas. Pass-through bent cutters involve processing predominantly high-strength types of metal, and therefore are usually made from carbide materials. When used in practice, they can be used to carry out both longitudinal and transverse feed. They allow you to trim the ends, chamfer, grind the top of workpieces, that is, perform all the basic operations that are inherent in turning units.

Being a wide-profile tool, the bent-type cutter has various variations in size. The most popular parameters are presented below.

The main working part of a bent cutter, as in the case of a straight product, is its head. It is located on a rod, which is subsequently inserted into the holder. Depending on the side of the inclination, the bent incisor can be left or right. This makes it possible to bend the part from different edges during processing.

Each model has its own unique angle. Thanks to this, the product becomes suitable for achieving a particular purpose. For example, to give the workpiece a stepped look, you will need a cutting tool with an angle of 90°.

The continuous stop cutter refers to turning structures used for turning rollers, sides and other cylindrical parts. Along with other products of a similar nature, it is actively used in workshops and machine-building shops for rough and/or finishing. The basic specification of the tool is to work with bodies of rotation that have steps. Usually these are parts with small dimensions. Due to the latter, persistent cutters are characterized by high accuracy.

The cutting edge of the tool is directed perpendicular to the axis of the workpiece. Due to this ratio, negative vibration that is formed during operation is minimized, and, consequently, the likelihood of damage or defects is reduced. To manufacture a continuous thrust cutter, the following are used: tool steel (fasteners are made from it), high-speed metal or carbide material (for the production of the cutting part).

These modifications of pass-through thrust cutters are further divided into left and right, which is determined by the position of the working part of the tool. Products vary in size, as a result of which they can have a rectangular or square cross-section.

When buying a cutter for a lathe, you should pay attention to the material of manufacture and dimensions, because these factors determine not only the price of the product, but also the target orientation. As for specific cost values, it is difficult to name them. The price range of cutters is quite wide and ranges from 200-1500 rubles

The price range of cutters is quite wide and ranges from 200-1500 rubles.

Types of cutters for a lathe and their purpose

When describing the types of turning tools, several classifying characteristics are usually used. According to its design, it is divided into two types: solid and prefabricated. In the first case, the entire product is made in the form of a monolithic bar of metal. And in the second, removable or soldered carbide plates act as the blade. According to their technological purpose, turning cutters are divided into special ones, which are used for processing various profiles and threading, and general purpose products, used for external and internal turning, cutting and end trimming. Another distinguishing feature of a turning tool is the configuration of the cutting part, which depends on its operating modes and the type of turning work. For turning hard-to-reach places, a curved cutter is usually used, which has several varieties, differing in the length of the cutting part, the shape of the bend, sharpening and purpose (cockerel, bent, reverse cutters and others).

Another classification option is the division of turning tools according to the principle of machining cleanliness. There are usually two classes here: rough and finishing. The first is intended for roughing or pre-turning operations, and the second is for finishing operations. If the rough tool, with rare exceptions, is quite the same type, then among the finishing tools there are a number of varieties with their own names. Examples include blade and radius cutters with an arcuate blade, the purpose of which is precise finishing turning. Another separate type is a diamond cutter, used for turning work on super-hard materials. A cup turning cutter with a circular cutting surface has a unique design that can work for a long time without regrinding.

In addition to the standard classification, there are many names for specific turning tools, usually reflecting the features of its design or technology of use. These include a spring cutter with a wave-shaped cutting part, which springs during turning of hard and uneven materials.

A separate category of cutting tools for lathes are planing cutters. During turning operations using them, feed is carried out on a stationary part. In this case, the allowance is not cut off, as during rotation, but is removed by planing. In this configuration, a lathe performs the same function as a planer or slotter.

Direct passes

Used for external processing of steel workpieces.

A pass-through turning cutter with a part fixed in a square-section caliper. Used when carrying out special piece operations.

Bent pass-throughs

Special equipment in which the working part is bent to the left or right. Used for trimming parts. With their help it is convenient to remove chamfers.

Thrust pass-throughs

Devices come with a straight and bent working element. Designed to work with cylindrical parts. The shape plus proper sharpening allows you to quickly remove most of the excess from the working surface of the workpiece.

Bent edges

They are equipment similar to a walk-through. However, there is a difference in the shape of the cutting edge. It is triangular, which allows for better processing.

Boring

Used for through and blind group holes, recesses, and recesses.

Threaded

They create carvings outside and inside, with a section in the shape of a trapezoid, rectangles and circles. Products can be smooth, convex or round.

For external thread

They are made of durable alloys (hardened steel, cermets), spear-shaped, allowing you to apply metric and other helical spiral lines of the required depth. Available in the three most common sizes: 25 by 16, 16 by 10 and 32 by 20 mm (the latter are relatively rare in use).

For internal thread

Relevant only for those parts that have technological holes of large cross-section. The main design feature is the presence of a serpentine head. The holders boast a significant length, necessary for the tool to penetrate deeply and carefully into the fixed workpiece during the operation. Suitable only for equipment that is equipped with a “guitar”. Their dimensions, in millimeters:

• 16 x 16 x 150;
• 20 x 20 x 200;
• 25 x 25 x 300.

Smooth

They differ from the previous version by maintaining rectangular edges.

Prefabricated

The working part of the cutter 1, into which the pin 3 is seated, a carbide plate 2 is put on it. It is secured with a wedge 5 and a screw 4. This way it is securely clamped in the cutter body.

The plates are produced in 3, 4, 5 and 6-sided versions. Advantages: reduced time for processing the part, good chip removal. Instead of sharpening, they rotate the plate.

The blades are cheaper than a whole chisel. You can place plates from different alloys on one holder in turn. Optimal for fine turning.

Measuring cutter angles

Each sample undergoes a procedure for measuring the listed characteristics. They are carried out using special measuring instruments. Use a table goniometer, or a mechanical one equipped with a vernier. The results obtained must be recorded in a journal.

The first type of meter allows you to determine the parameters of angles located on the main plane. Structurally, it consists of the following parts:

• massive base;
• stands with a moving template (to set the direction of the planes);
• measuring sector (equipped with a degree ruler);
• locking screw (to fix the received direction).

Measuring turning tool angles

The sequence of measurements is carried out as follows. The selected sample is placed on the base. The surface of the edge is combined with one plane of the stand. The second is directed parallel to the edge being examined. The resulting values ​​on the degree ruler are the value of the measured indicator. A prerequisite for carrying out measurements is to ensure a tight fit of the template to the corresponding surface of the cutter.

The measurement of such specific parameters as plan angles is carried out with a mechanical inclinometer equipped with a vernier. Its design includes the following main elements:

• two special sectors, each of which has its own angular scale;
• two independent measuring guides;
• special movable vernier.

The sequence of measurements is slightly different from the sequence of operations of a desktop inclinometer.

Special stand for measuring cutter angles

To obtain the exact value of the parameter, it is necessary to accurately align one strip with the side surface of the case. The cutting edge should be directed parallel to the second bar. Numerical values ​​are read using the existing built-in vernier. The obtained values ​​are recorded in the documentation.

Geometry of turning tools

Image: geometry of a turning tool.

Let's talk about the angles of the incisors and their purposes.

1. Back auxiliary angle (α1). As it decreases, the friction force between the rear plane of the tool and the workpiece decreases.
2. Apex angle (ε). Formed between the cutting edge and the rear auxiliary plane. The larger this angle, the better the heat removal conditions and the higher the strength of the cutter.
3. Auxiliary plan angle (ϕ1). Its size varies from 10 to 30°. As the angle decreases, the cleanliness of the treatment improves, but the friction force increases.
4. Leading angle (ϕ). Its size varies from 20 to 90°. The length and width of the cut depend on the size of the angle. The smaller ϕ, the lower the temperature and cutting force. The cleanliness of the processing is also improved. But as the angle decreases, vibration and radial cutting force increase.
5. Cutting angle (δ). Formed between the rake surface and the cutting plane.
6. Basic rake angle (γ). Its size varies from -5 to +15°. As the angle increases, it is easier for the tool to cut into the metal, chip removal is improved, and the cutting force, deformation of the machined surface, and power consumption are reduced. However, this reduces heat dissipation and reduces the service life of the cutting edge.
7. Taper angle (β). Formed between the front and main back surfaces. Affects the sharpness and strength of the tool.
8. Main relief angle (α). Its size varies from 6 to 12°. As the angle decreases, the friction force between the part and the back surface of the cutter decreases. This improves heat dissipation and extends the service life of the tool, but the cleanliness of the machined surface deteriorates.
9. Angle of inclination of the main cutting edge (λ). Affects the direction of chip removal. At positive λ and λ = 0°, the chips move towards the machined surface. Cutters with positive λ (12–15°) are used when processing workpieces made of heat-resistant and hardened steels. For universal turning tools, λ = 0°. Cutters with negative λ are used for finishing.

Practical work. Select a cutter for a specific operation and give it a brief description

Practical work

Select a cutter for a specific operation and give a brief description of the cutter.

The purpose of the work is to study the geometric and structural elements of various types of turning tools.

1. Theoretical part

Basic elements of a turning tool

Turning cutters are used on lathes to produce cylindrical and conical parts from workpieces; shaped and end surfaces formed as a result of rotation of the workpiece and translational movement of the cutter.

The cutting tool (Fig. PZ 9.1) consists of a working part - cutter head 1 and a connecting part - cutter body 6.

Rice. PZ 9.1 Basic elements of a turning tool

The cutter body with a supporting plane serves to secure it in the tool holder. The cutter head is formed by special sharpening, and its main elements are the rake face, flank faces, cutting edges and tip.

The front surface is the surface of the cutter along which the chips flow.

The rear surfaces of the cutter are those facing the workpiece being processed.

Cutting edges are formed by the intersection of the front and rear surfaces.

The main cutting edge (blade) performs the main cutting work and is formed by the intersection of the front and main rear surfaces.

The auxiliary cutting edge (blade) is formed by the intersection of the front and auxiliary rear surfaces. There can be two auxiliary cutting edges (for example, a cutting cutter).

The tip of the cutter is the junction of the main and auxiliary cutting edges. With a curved mating of the cutting edges, the apex has a rounded shape with a radius r (see Fig. PZ 9.3).

1. Classification of incisors

Incisors are divided as follows.

1. Based on the type of machine (Fig. PZ 9.2), a distinction is made between turning, planing and slotting cutters.

Rice. PZ 9.2. Turning, planing (b) and slotting (c) cutters:

Dspop and Dsvpr - directions of movement of the transverse and longitudinal feeds, respectively; Dr—direction of the main movement (rotation of the workpiece); Dsв— vertical feed

Rice. PZ 9.3 Determination of left (a) and right incisors (b)

1. According to the direction of feed (Fig. PR9.Z), right and left incisors are distinguished.

Right

are called incisors, the main cutting edge of which, when the palm of the right hand is placed on them (so that the four fingers are directed towards the apex), turns out to be located on the side of the thumb. When working on a lathe, such cutters move from right to left (from the tailstock to the front).

Left

are called incisors, the main cutting edge of which, when the palm of the left hand is applied to them (as indicated earlier), turns out to be located on the side of the thumb.

1. Based on the design of the head relative to the shaft, the incisors are divided into straight (Fig. PR 9.4, a), bent (Fig. PR 9.4, b), curved (Fig. PR 9.4, c) and with a retracted head (Fig. PR 9.4, d).

Up Up

Left Right Left Right (forward) (backward)

Rice. PR 9.4. Incisors are straight (a), bent (b), curved (c) and with a retracted head (d)

1. Based on the cross-section of the rod, rectangular, square and round incisors are distinguished.
2. According to their purpose (Fig. PR1.5), the following cutters are distinguished: through cutters - turning the part along the axis of its rotation or in a plane perpendicular to this axis (Fig. PR 9.5, a-c);

Rice. PR 9.5. Types of incisors. determined by purpose:

a - a straight line; b - bent passage; c - pass-through persistent; g - cutting; d - boring for through holes; c - boring for blind holes (thrust); g - cutting; z - slotted; and - threaded; k - shaped rod; l - shaped prismatic; m - shaped round (disc)

Rice. PR 9 6. Types of cutters, determined by the method of fastening their cutting part:

a - solid; b - butt welded; c - with a soldered plate; g - with mechanical fastening of the plate

scoring - used for cutting ledges at right and acute angles to the main direction of turning (Fig. PR9.5, d); boring - for boring through and blind holes in the direction of the axis of rotation (Fig. PR9.5, y, e); cutting - used for cutting material at right angles to the axis of rotation and for cutting narrow grooves (Fig. PK9.5. g, h); shaped - used to obtain a complex shaped shape of the part being turned (Fig. PR9.5., k-m)

1. According to the nature of processing, roughing and finishing cutters are distinguished. fine turning.
2. According to the type of material, cutters with plates made of carbide, high-speed steel and mineral ceramics are distinguished.
3. According to the method of fastening the cutting part (Fig. PR9.6), the cutters are divided into solid, butt-welded, with a soldered plate and with a mechanical fastening of the plate.

On the workpiece being processed (Fig. PR9.7), a distinction is made between the processed surface, the machined surface and the cutting surface.

Rice. PR.9.7 Surfaces of the workpiece formed during processing with a cutter: 1 - processed surface; 2 - cutting surface; 3 - processed surface; 4 — cutting plane; 5 - main plane.

Under the surface to be treated

refers to the surface of the workpiece that is partially or completely removed during processing.
The machined surface
to the surface formed on the workpiece as a result of processing. The cutting surface is the surface formed on the workpiece directly by the main cutting edge.

Geometric parameters of the cutting part of the cutter

To study the geometry of a turning cutter, four coordinate planes are established (Fig. PR 9.8): cutting plane, main plane, main and auxiliary cutting planes.

Cutting plane Рn— coordinate plane tangent to the cutting surface and passing the main cutting edge perpendicular to the main plane,

Rice. PR9.8. Geometry of the cutting part of the cutter

The main plane Pv is a coordinate plane drawn through the point of the cutting edge under consideration, parallel to the transverse and longitudinal feeds of the cutter.

The main cutting plane Рτ, (section N-N) is a coordinate plane perpendicular to the projection of the main cutting edge onto the main plane.

Auxiliary cutting plane Pτ1 (section Nl - M1) is a coordinate plane perpendicular to the projection of the auxiliary cutting edge onto the main plane.

The main angles of the cutter are measured in the main cutting plane Рτ (see section N-N in Fig. PR9.8). The main angles of a cutter include the main rake angle, the main clearance angle, the point angle and the cutting angle.

The main rake angle γ is the angle between the rake surface of the cutter and a plane perpendicular to the cutting plane and passing through the main cutting edge. This angle can be:

— positive (+γ) — when the front surface is directed downward from the plane perpendicular to the cutting plane;

- equal to zero - when the front surface is perpendicular to the plane perpendicular to the cutting plane;

- negative (-γ) - when the front surface is directed upward from the plane perpendicular to the cutting plane.

With a positive value of the rake angle γ, the following dependencies exist between the cutter angles:

α+β+γ=900

1. α+β=δ

δ+γ=900

δ=900 -γ

For a negative rake angle γ, the cutting angle δ is determined by the formula

δ=900 + γ

A positive rake angle γ facilitates the cutting process and ensures freer flow of chips along the rake surface, and also reduces the deformation of the cut layer, cutting forces and power consumption.

At the same time, an increase in the rake angle leads to a decrease in the cutting angle δ, i.e. to weakening of the cutting wedge, reducing its strength and increasing wear of the cutter. Therefore, when processing hard and brittle materials, small rake angles should be used to increase the strength and durability of the tool, and large rake angles should be used when processing soft and viscous materials.

Main clearance angle α

is the angle between the tangent to the main flank surface of the cutter at the cutting edge point in question and the cutting plane. Clearance angles reduce friction between the tool flanks and the cutting surface and the machined surface.

Taper angle β

- this is the angle between the front and main back surfaces of the cutter.

Cutting angle δ

is the angle between the front surface of the cutter and the cutting plane.

Auxiliary angles

cutters are measured in the auxiliary cutting plane Pτ1 (see section N1-N1 in Fig. PR 9.8).

Auxiliary clearance angle α1

, is the angle between the auxiliary rear surface and the plane passing through the auxiliary cutting edge of the cutter perpendicular to the main plane.

Plan angles are considered in the main plane Pv. These include the principal leading angle, the minor leading angle and the leading leading angle.

Main plan angle

φ is the angle between the projection of the main cutting edge of the cutter onto the main plane and the feed direction.

The auxiliary plan angle φʹ is the angle between the projection of the auxiliary cutting edge of the cutter and the direction opposite to the feed.

Vertex angle in plan

ε is the angle between the projections of the main and auxiliary cutting edges of the cutter onto the main plane Pv

Rice. PR9.9. Angles of inclination of the main cutting edge: a - negative; b - equal to zero; in - positive

13

Rice. PR9.10. Influence of the angle of inclination of the main cutting edge on the direction of chip flow

Rice. PR 9.11. Turning cutters equipped with carbide inserts:

a - straight; b - bend it; Ι-ΙΙ — cutter positions

From Fig. PR9.8 shows that the sum of the angles in the plan is equal to 1800, i.e.

φ+φ'+ε=1800.

Main cutting edge angle

λ (see Fig. PR9.8 view A on the main rear surface) is the angle between the main cutting edge of the cutter and a line drawn through its top parallel to the main plane. The angle is measured in a plane passing through the main cutting edge of the cutter perpendicular to the main plane (cutting plane Pn).

The inclination angle of the main cutting edge λ can be:

negative - when the tip of the cutter is the highest point of the cutting edge (Fig. PR 9.9, a);

equal to zero - when the main cutting edge is parallel to the main plane (Fig. PR 9.9, b);

positive - when the tip of the cutter is the lowest point of the cutting edge (Fig. PR 9.9, c).

Rice. PR 9.12. Turning cutters. equipped with carbide inserts:

a - pass-through persistent; b - scoring (end)

Rice. LR9.14. Lathe cut-off cutter equipped with carbide insert

Angle λ affects the direction of chip flow (Fig. PR9.10), as well as the strength of the cutter head and cutting edge, which is especially important for intermittent cutting.

With a positive value of the angle λ (the cutting edge is above the tip of the cutter), the chips move back from the cutting edge towards the formed surface of the workpiece and can thus deteriorate the quality of processing (Fig. PR9.10, a). When processing viscous materials at a negative angle λ (cutting edge below the tip of the cutter), the chips move forward in the direction of tool feed Ds (Fig. PR9.10, b).

The geometric parameters of some turning tools are shown in Fig. PR9, 11—PR9.16.

The right turning straight cutter with φ = 450 is shown in Fig. PR 9.11, a, and the right turning bent cutter with φ = 450 is shown in Fig. PR9.11, b. Passing cutters are used for processing the workpiece along the axis (see Fig. PR9.11, a, b, pos. 1) and for trimming the end (see Fig. PR9.11, b, pos. P).

Rice. PR9.15. Pass-through bent cutter of Kolesov design

Passage

thrust cutter shown in fig. PR9.12, a, is used for longitudinal turning with simultaneous processing of the end surface making a right angle with the cylindrical surface.

Scoring

cutters (see Fig. PR9.12, b) are used to process workpiece surfaces in a direction perpendicular or inclined to the axis of rotation. To trim the end (with transverse feed), a continuous thrust cutter can also be used (see Fig. PR9.12, a), for which it must be rotated at a certain angle in order to form an auxiliary corner in the plan.

A turning boring cutter (φ = 600, φ' = 300), used for machining through holes, is shown in Fig. PR.9.13, a, and a turning boring cutter used for machining blind holes (at point-blank range) - in Fig. PR9.1Z, b.

The cutting cutter used for cutting (cutting) the workpiece is shown in Fig. PR.9.14.

The bent cutter of the Kolesov design with a cleaning edge is shown in Fig. PR9.15. The length of the cleaning edge of such a cutter should be (1.1…1.2), where So is the feed per revolution of the spindle, mm/rev.

Passing stop cutter

Kolesov's design is shown in Fig. PR 9.16. The edge of such a cutter with a width of 1.15So, located in plan at an angle φ'= O, cuts off the scallops remaining on the treated surface.

Rice. PR9.16. Passing thrust cutter of Kolesov design

1. Geometric parameters of the cutting part of turning tools during processing.

Previously, we examined the angles of turning cutters in static conditions based on the fact that the tip of the cutter is mounted on the axis of the part, there is no feed movement and the cutting plane is perpendicular to the main plane (Fig. PR 9.17, a).

Rice. PR 9.17. Changing cutting angles depending on the position of the cutter tip relative to the center line:

a - on the line of centers; b - above the line of centers; c - below the line of centers; 1 - detail; 2 - cutter; В—В—theoretical cutting plane; A'—A'; A"-A"—actual cutting planes; τ—angle

rotation of the cutting plane; αд—actual clearance angle; γд — actual rake angle; h—displacement of the cutter apex; D - workpiece diameter

When processing conditions change, the front and rear cutting angles change. When setting the tip of the cutter above the axis of rotation of the workpiece during external turning, the rear angle a decreases and the front angle increases (Fig. PR9.17, b). When setting the tip of the cutter below the axis of rotation of the workpiece during external turning, the rear angle a increases and the rake angle y decreases (Fig. PR 9.17, c). In this case, the actual static clearance angles are determined accordingly by the formulas

αд=α±τ; γд=τ±γ

When internal machining (boring) and setting the tip of the cutter below the axis of rotation of the workpiece, the rake angle increases and the back angle decreases.

Setting the cutter tip above the workpiece axis during external turning with an offset h = (0.01 ... 0.2), where D is the workpiece diameter, mm, is allowed only during preliminary processing.

When finishing, the cutter must be installed with its tip along the axis of the workpiece or below it with an offset h. Otherwise, if the rigidity is insufficient, the cutter may bend, cut into the workpiece and begin to cut a layer of greater depth, which will lead to a change in the diameter of the machined surface and will cause scrap.

Method for measuring cutter angles

The cross-sectional area of ​​the cutter body (B x H, mm2) is determined using a caliper or a measuring ruler.

The scheme for measuring the main angle φ using a universal angle meter is shown in Fig. PR9.18 (measurement accuracy is 2′). When measuring the angle φ in plan, the protractor bar 1 is applied to the cutting edge, and the protractor bar 3 is applied to the side of the cutter 2. Readings are taken using the protractor scale.

The auxiliary plan angle φ' is measured similarly

Vertex angle in plan

ε=1800-(φ-φ')

To measure the angles of cutters, inclinometers of different designs and purposes are used: the universal inclinometer D S. Semenov, the desktop inclinometer designed by MIZ, and the plumb inclinometer designed by VNII.

These protractors belong to the type of devices that operate by contact method with reading of measurement results on a degree scale.

Universal goniometer by D.S. Semenov.

This device is designed to measure external and internal angles of the cutter, as well as heights. In tool making, it is used to measure the rake angle γ, the main and auxiliary clearance angles α and α1, the main and auxiliary lead angles φ and φ'.

Such a protractor (Fig. PR 9.19, a) consists of a sector (or base) 5, on which the main degree scale 6 is applied. A plate 4 with a vernier moves along the sector, on which, using a holder 3, a square 2 is fixed, connected to a removable pattern ruler 1. The main scale of the protractor is graduated from 0 to 1300, but through various reinstallations of the measuring parts it is possible to measure

Rice. PR 9.18. Scheme for measuring the angle of cutters in plan:

1, 3 — strips; 2 - cutter; 4 - vernier

Rice. PR 9.19. Universal goniometer by D. S. Semenov:

a - diagram for measuring the front angle of the cutter; b - diagram for measuring the rear right corner; c - scheme for measuring the main angle in plan;

d - diagram for measuring the auxiliary angle in plan; 1 — movable pattern ruler; 2 - square; 3 - holder; 4 — plate with vernier; 5 — base (sector); 6 - degree scale

angles from 0 to 3200. The reading accuracy on the vernier is 2…5′, and on the degree scale 10…30′.

The measurement method using such a protractor comes down to installing the measured surfaces between the movable ruler of sector 5 and the movable ruler 1 so that the necessary contact is formed, i.e. invisible or visible uniform clearance.

In Fig. PR9.19, a - d shows diagrams for measuring the angles of a turning right cutter.

Tabletop protractor of MIZ design. This device is used to measure the front γ, main α and auxiliary α1, rear angles, as well as the inclination angle of the main cutting edge λ.

Such a protractor (Fig. PR 9.20) consists of a plate (or base) 1, which serves as the main plane, a vertical post 4, along which a scale device 2 with a rotating measuring ruler 6 moves. The measuring ruler is equipped with a pointer and two measuring knives. The scale device 2 is guided by a key along the keyway and, if necessary, using the lock 3, it is installed in any height position.

Rice. PR 9.20. Table goniometer MIZ design:

1 - plate (base); 2 — scale device; 3 - clamp; 4 - stand; 5 - screw; 6 - measuring ruler

The position of one of the knives of the measuring ruler in relation to the surface being measured is fixed using screw 5. When measuring the front γ and rear α and α1 angles, the cutting

the blades of the cutter are installed parallel to the transverse marks of plate 1 (in this case, the cutting plane passes through the knives of the measuring ruler), and the knife of the measuring ruler is aligned with the front or rear surface of the cutter. The reading is made on the scale of the protractor using the mark of the measuring ruler 6. If, when measuring the front angle γ, the mark of the measuring ruler deviates to the left, and when measuring the rear angles - to the right, then the measured angles have negative values.

When measuring the angle λ, the main cutting blade of the cutter is installed parallel to the longitudinal marks of the slab, and the knife of the measuring ruler is aligned with the main cutting blade. If the line of the measuring ruler deviates to the right from zero, then the angle is considered negative, and if to the left, it is considered positive.

Protractor with a plumb line designed by VNII.

The design of this protractor (Fig. PR 9.21, a) is based on the use of the properties of a conventional pendulum. which, under the influence of a load (plumb line) 8, always tends to take a vertical position. A ruler 7 is screwed to the base (body) 1 of the device, and a brake washer 4 and an arrow 3 with a weight 8 are mounted on a freely rotating axis 5. On the disk 2, located in the bore of the body 1, there is a circular scale, divided into four equal parts (from 0 up to 450) and having a division value of 1 0. Axis 5 together with arrow 3 is fixed motionless at various positions of the inclinometer using brake 9. Disc 2 is covered with a transparent plexiglass cover 6.

Checking the adjustment of such a protractor to the zero position of the scale is carried out by aligning the working edge of the ruler 7 with the plane of the control plate, precisely set in level. When brake 9 is released, needle 3 of the instrument should be set to the zero scale division.

The considered protractor is suitable for measuring various angles of most types of cutting tools, in which the length of straight sections on the front and rear surfaces is at least 1 mm.

Measurement using such an inclinometer is as follows: the edge of the ruler is applied in the appropriate direction to the surface of the tool, the angle of inclination of which you want to determine, and the brake button is pressed, thereby releasing the weight that sets the inclinometer arrow to a vertical position. After the pointer stops swinging, the brake button is released and the scale is counted. Examples of using a goniometer with a plumb line when inspecting prismatic cutters, drills, countersinks, reamers and cutters are shown in Fig. PR 9.21, d, f.

Rice. PR9.21. Protractor with a plumb line designed by VNII:

a - general view 6-d - measurement of angles γ, λ, φ, cutter; d, f - measurement of angles γ, ω of the cutter; 1 - body; 2 — disk; 3 - arrow: 4 - brake washer; 5 - axis; b - cover; 7 - ruler; 8 — cargo; 9 - brake

1. Necessary equipment

To perform laboratory work you will need the following equipment and tools:

set of turning cutters;

calipers, measuring ruler, universal angle gauge by D.S. Semenov, desktop inclinometer designed by MIZ, inclinometer with plumb line designed by VNII.

1. Work order

1. Study the structural elements and geometric parameters of turning tools.
2. Draw in a notebook sketches of turning cutters: through, cutting, boring and scoring, with all the geometric parameters set (as instructed by the teacher), as well as a diagram for measuring angles. Show the direction of feed movement Ds

H. Study the designs of the universal protractor D.S. Semenov and a table goniometer designed by MIZ

1. Study the principles of operation of measuring instruments (calipers, inclinometers).
2. Measure all geometric and design parameters of the cutters listed in paragraph 2.

Present the measurement results in the form of a table. PR 9.1.

Table PR 9.1. Results of measurements of design and geometric parameters of cutters.

1. Contents of the work report

The report on the laboratory work performed must contain: 1. The title and purpose of the work.

2. Sketches of turning tools indicating their design and geometric parameters.

3. Calculation of cutting angles for turning tools.

4. Conclusions based on the results of the work.

CONTROL QUESTIONS

1. 1. Name the main elements of the cutter
2. 2. How are incisors classified according to the shape and location of the head relative to the shaft?

3. Name and show the surfaces of the workpiece formed during the processing process.

1. What is taken to be the main plane of the cutter?
2. Define the cutting plane. main and auxiliary cutting planes of the main plane.

6. What angles are shown in the main cutting plane?

7. What angles are shown in the auxiliary cutting plane?

B. Define cutting angle δ.

1. What is the difference between the cutting angles for a positive rake angle γ?
2. Show on the cutter the inclination angle of the main cutting edge λ.
3. What angles are shown in the main plane and what relationship exists between them?
4. How are cutters classified by type of processing?
5. What do cutter holder sizes affect?
6. How are cutters divided according to the direction of movement in feeds?
7. Which surface of the incisor is called the front?

16. Name the distinctive features of straight lines. bent and curved incisors.

17. Decipher the marking of the material from which the cutter is made.

18. What rake angle should the cutter have if its back angle is α = 15 0 and the sharpening angle is β = 700?

1. What will be the sharpening angle β of the cutter if its rear angle is α = 15 0, and its rake angle is γ = 100?
2. How does the clearance angle affect the cutting process?
3. What cutter angle affects the direction of chip flow?

5

Cutters for lathes - what to look for

When choosing this metal-cutting tool, you need to pay attention to the following basic parameters:

1. material and geometry of the cutting part;
2. chip breaking method;
3. strength and vibration resistance of cutting edges and holder;
4. shape and dimensions of a removable or welded plate;
5. geometry, design and roughness of the plate socket;
6. durability and dimensional stability of the cutter;
7. cutter angles;
8. ensuring the specified roughness of the processed surface.

Measuring the sharpening angles of a turning tool

For maximum accuracy of the result, it must be performed only with specialized manual equipment. It consists of the following parts:

• base - all other elements are attached to it;
• movable template for the stand, adjustable to a convenient position;
• graduated scale making it possible to read readings;
• a locking screw that allows you to mark and store the direction of value changes.

The algorithm for recording the results is as follows:

• place the tool;
• apply its edge;
• look how much it shows - the found figure will be the actual degree.

The method is easy to implement and quite accurate. By the way, taking into account possible differences in the geometry of turning tools, it is recommended to determine the entering angles using equipment equipped with a vernier.

Marking according to GOST

Requirements for the production of metalworking machines, as well as auxiliary equipment, are strictly regulated by the requirements of interstate standards.

There are much fewer requirements for the rods of cutting devices compared to the elements of the contact group. They are made from steel grade 45 or 50.

There is a separate standard for each type of design. For example, the production of cutters with upper clamping of a replaceable plate is regulated by GOST 26611-85.

In the production of high-speed steel plates, cobalt compounds are used:

• R9K5;
• R9K10;
• R18F2K5.

After heat treatment, their hardness reaches 67 HRC.

There are special requirements for the surface roughness of devices. After finishing the front and rear parts, the degree of cleanliness must correspond to class 9.

Symbols in accordance with the requirements of the interstate standard are applied to the side surface.

As an example, let's decipher the T15K6 marking:

1. "T". The first letter indicates that a solid composition of the titanium group was used as the manufacturing material.
2. "15". The number indicates the mass fraction of titanium carbide in the product.
3. "TO". The product contains cobalt.
4. "6". Mass fraction of the above chemical element.

Tool classification

There are many parameters for classifying cutters in accordance with current GOSTs. According to the design features, the following types of turning tools are distinguished:

• monolithic, in which the cutting head and holder are a solid structure;
• prefabricated ones, in which a high-speed alloy plate is soldered on the head, providing increased processing efficiency - this is one of the most common types of tools;
• prefabricated, with a mechanically fixed plate - the plate is fixed on the head by a bolt; in this configuration, cutters with metal-ceramic plates are made;
• adjustable.

Functionality of cutters

Depending on the quality of processing, turning tools are divided into roughing and finishing. The geometry of the roughing tool allows for the removal of thick material and maintains hardness under the intense heat that occurs at high processing speeds. Finishing analogues have a different purpose; they are needed to work at low speeds to remove a small thickness of material.

The tool is also classified according to the feed direction, according to which right and left cutters are distinguished. The feed direction refers to the side on which the main cutting edge of the tool is located at the moment when its head is facing the front of the workpiece.

Types of incisors

Functional purpose is one of the main classification parameters of this tool. According to their purpose, turning tools are divided into:

1. Cutting (GOST No. 18874-73) - used on machines with transverse feed of working tools, intended for sheathing and processing of the end parts of workpieces.
2. Pass-through (GOST No. 18871-73) - can be installed on machines with both transverse and longitudinal feed. They are used for trimming ends, turning, forming parts of conical and cylindrical shapes.
3. Cutting, also known as groove (GOST No. 18874-73) - mounted on machines with transverse feed. Used for cutting monolithic pieces of metal and turning ring-shaped grooves.
4. Boring (GOST No. 18872-73) - designed for boring holes (through and blind), forming recesses and recesses.
5. Shaped (GOST 18875-73) - used to remove external and internal chamfers.
6. Threaded (GOST No. 18885-73) - allow you to cut threads of metric, inch and trapezoidal sections (both internal and external).

Also, turning cutters are divided into straight, bent and drawn depending on the position of the cutting edge in relation to the holder. In bent ones the edge is made in the form of a straight line, in bent ones it is curved, in drawn ones the edge is narrower than the width of the rod.

Which cutters to choose, where to buy?

To determine which cutters are needed specifically in your case, you need to decide on the following points:

• what metal you will process and what operations will be performed;
• prioritize quality, processing efficiency and tool wear resistance.

In general, a novice turner needs to have three types of cutters at his disposal: passing (marked SDACR) - for processing ends, external neutral type (SDNCN) and boring (SDQCR). This is a basic kit that allows you to perform most technological operations.

If you are interested in buying a tool for long-term use, it makes sense to buy a set of turning tools with replaceable inserts. Subsequently, you will be able to change consumables rather than buy new holders after the cutting head wears out.

A few words about the manufacturers. Among the companies that sell really high-quality products that are worth buying, we highlight the companies Hoffman Garant (Germany) and Proma (Czech Republic). In the segment of domestic manufacturers, the companies SiTO (Gomel Tool Plant) and Kalibr deserve attention. You can order cutters with delivery using the links provided.

It also makes sense to purchase a sharpening machine that will allow you to return the cutters to their functionality when worn out yourself, rather than using the services of third-party craftsmen. Here you need a sharpening and grinding unit equipped with a constant cooling system with two abrasive wheels - made of silicon carbide (for cutters made of high-speed alloys) and electrocorundum (for carbide tools). When sharpening, it is initially necessary to process the front plane of the cutting head, then the additional and rear ones, until a smooth cutting edge is formed.

Making your own cutters: a step-by-step guide

The main thing is to use only tool steel that has sufficiently high performance characteristics.

Experts recommend choosing an alloy or high-speed carbon version.

Selecting the required configuration of files or rasps

The selection of these parts will be easier if the owner knows in advance exactly what tasks he faces. After this, choosing the length, shape and size will not be difficult. Here are some tips.

• If you need to file up to 5-10 mm in thickness, it is better to stop at cut number 0 or 1.
• The processing accuracy should be within 0.01-0.02 mm.
• It is much easier to choose devices based on length.

The main guideline is the dimensions of the surface that needs to be sawed. The larger this parameter, the larger the device itself should be.

You can use a specific formula to make the calculation more accurate. We add 15 cm to the length of the surface of the product. We get the value, which will be the length of the working surface of the file or rasp. The main thing is that when working, the tool is passed over the entire workpiece.

Fastening cutting parts

Homemade tools do the same as professional ones. The optimal solution is self-tapping screws. The higher quality the product, the better.

How to install a parting cutter

In order to perform cutting correctly without increased wear of the cutting plate, as well as to ensure the required quality of the end after cutting, it is necessary to align the cutter strictly perpendicular to the part. In addition, it must be installed opposite the axis of rotation with a vertical deviation of no more than ± 0.1 mm. Placing the edge of the blade even a few tenths of a millimeter higher can cause the cutting blade to break, and placing it too low can leave an uncut step on the workpiece. Cutting must be done as close to the chuck jaws as possible, using a cutter with a minimum overhang.

To facilitate the processing of complex materials on desktop machines, spring and inverted cutters are used. But, probably, craftsmen use other designs for these purposes, as well as various improvements to “standard” cutters. If you know anything about this, please share information in the comments to this article.

Plan angles

For a cutting tool, they have the following names of plan angles:

• main angle;
• auxiliary;
• corner located at the apex.

The first is formed between the plane of the edge projection and the main plane of the tool.

The second is determined between the continuation of the projection of the cutting edge with a plane directed along the movement of the workpiece.

Cutter angles in plan

The third is between the first listed plane and the main plane.

The numerical values ​​of the parameter located at the vertex can take positive and negative values. It turns out positive when the top of the sharpening point is at the lowest point of the workpiece. Minus sign - the peak reaches its highest point.

Operating rules

Turning cutters are capable of performing their main function for a long time until the working surface is ground down. But improper use will shorten the life of the tool. To prevent preliminary wear, you need to follow simple operating rules:

• Install centrally.
• The larger the dimensions of the workpiece, the larger the cutter should be.
• Turn on cooling when operating in heavy conditions.
• Sharpen in a timely manner.
• Periodically polish the working surfaces with a fine-grained stone without removing the tool from the tool holder.
• Apply the tool to the workpiece manually, and after touching, turn on the automatic feed.
• When stopping the machine, first manually retract the tool, then turn off the unit.
• Select the correct cutting modes.
• Do not store the tool in a pile - this will lead to chips and cracks on the cutting edge.
• When working with a cutting tool, bring it as close to the chuck as possible.

Many types of work are performed on a lathe. A separate cutter is provided for each process. It is selected based on the material being processed, cutting conditions, cleanliness and roughness parameters. The tool must be sharpened in a timely manner, and the rules of operation and storage must be followed.

Principal angles

One received the name - the main front angle. The second one is called the main rear one.

Each influences the processing result:

• The first directly determines the quality of the surface being removed (the resulting chips). If it increases, increased deformation occurs in the upper layer. A low value allows the tool to remove excess metal much easier. Does not cause increased compression of this layer. Significantly facilitates the process of removing and draining excess metal.
• An increase in the numerical value of the second weakens the reliability of fastening the tool to the tool holder. Promotes an increase in the frequency and amplitude of vibrations. Changing the characteristics increases the wear rate of the cutter. Decreasing the value increases the contact area of ​​the cutting edge with the machined surface. This leads to an increase in the temperature of the cutter.

Angle of inclination of the cutting edge of the cutter

Sets of cutters with other parameters

Cutters for a metal lathe 8x8 mm from the Czech company Proma are represented by eleven tools. By means of soldering, they are equipped with carbide plates. The cutter sizes in this set are 80 mm and 125 mm.

Those who need a tool with a tail section of 0.12 cm for work can use cutters for a 12x12 mm metal lathe. A wide range of work can be performed using the following cutters:

• pass-through bent;
• persistent;
• threaded;
• boring;
• cutting;
• slotted and other types of cutters.

In the modern tool market, a wide range of different products for metalworking equipment is available to the consumer. For a beginner who has decided to purchase a set of cutters for a metal lathe, experts recommend that they familiarize themselves in detail with the classification of these tools, carefully study their design features and characteristics, so that they do not have to regret their purchase in the future.