Classification of turning tools for metal. Heat treatment of products

Heat treatment is a set of processes of heating metals to a given temperature, holding and cooling in order to impart certain physical and mechanical properties to the workpiece as a result of changing the structure (internal structure) of the part. Material for workpieces – non-ferrous metals, steel.

Main types of heat treatment:

1. Annealing of the 1st or 2nd kind. In the process of heating metals to a certain temperature, after holding and cooling, an equilibrium structure is obtained, viscosity and ductility increase, and the hardness and strength of the workpiece decreases.
2. Hardening with or without polymer transformation. The purpose of heat treatment is to increase the strength and hardness parameters of the material due to the formation of a nonequilibrium structure. It is used for those alloys that undergo phase transformations in the solid state during heating and cooling processes.
3. Vacation. Strong steels and hardened metal alloys are subjected to it. The main parameters of the method are heating temperature, cooling rate, holding time.
4. Aging applies to alloys that have been quenched without polymorphic transformation. After hardening, the strength and hardness of magnesium, aluminum, nickel, and copper steels increases.
5. Chemical-thermal treatment. The technological process changes the chemical composition, structure and surface properties of parts. After treatment, the wear resistance, hardness, fatigue and contact endurance, and anti-corrosion resistance of the material increase.
6. Thermo-mechanical treatment. This type includes the process of plastic deformation, which creates an increased density of defects (dislocations) in the crystal structure of the workpiece. This method is used for aluminum and magnesium alloys.

Welding, electric and turning processing method

Welding is the production of a permanent connection of a steel part by heating to melting or to a highly plastic state. During processing, the material melts along the edge of the parts being joined, mixes and hardens, forming a seam after cooling. There are electric (arc or contact) and chemical (thermite or gas) welding.

Turning method of processing - manual work on special machines in order to remove the excess layer and give parts certain shapes, roughness, accuracy, dimensions. The main types, depending on the purpose of the work: basic, repair and assembly.

Electrical metalworking methods include:

1. Electric spark method. This method is based on the phenomenon of destruction of durable metals under the influence of electric spark discharges.
2. Ultrasonic method. Using special installations, precious stones, hard alloys, hardened steel and other materials are processed.

Metal casting

The technological process of casting consists in the fact that parts are obtained after pouring molten metal into certain molds. Various materials are used:

• cast iron;
• steel;
• copper, magnesium, aluminum and zinc alloys.

Metal in its various forms, including numerous alloys, is one of the most popular and widely used materials. It is from it that a lot of parts are made, as well as a huge number of other popular items. But in order to obtain any product or part, you need to make a lot of effort, study the processing processes and properties of the material. The main types of metal processing are carried out according to different principles of influence on the surface of the workpiece: thermal, chemical, artistic influence, using cutting or pressure.

Thermal effect on a material is the influence of heat in order to change the necessary parameters regarding the properties and structure of a solid substance. The process is most often used in the production of various machine parts, and at different stages of production. The main types of heat treatment of metals: annealing, hardening and tempering. Each process affects the product in its own way and is carried out at different temperatures. Additional types of influence of heat on a material are operations such as cold treatment and aging.

Technological processes for producing parts or workpieces through force on the surface being processed include different types of metal forming. Among these operations, there are several that are most popular in use. Thus, rolling occurs by compressing the workpiece between a pair of rotating rolls. Rolls can be of different shapes, depending on the requirements for the part. When pressing, the material is enclosed in a closed form, from where it is then extruded into a smaller form. Drawing is the process of drawing a workpiece through a gradually narrowing hole. Under the influence of pressure, forging, volumetric and sheet stamping are also performed.

Features of artistic metal processing

Creativity and craftsmanship reflect the various types of artistic metalworking. Among them, we can note a couple of the most ancient, studied and used by our ancestors - this is casting and. Although not much behind them in terms of appearance was another method of influence, namely, minting.

Embossing is the process of creating pictures on a metal surface. The technology itself involves applying pressure to a previously applied relief. It is noteworthy that embossing can be done both on a cold and on a heated working surface. These conditions depend, first of all, on the properties of a particular material, as well as on the capabilities of the tools used in the work.

Methods of mechanical processing of metals

Types of mechanical processing of metals deserve special attention. In another way, mechanical action can be called the cutting method. This method is considered traditional and the most common. It is worth noting that the main subtypes of this method are various manipulations with the working material: cutting, cutting, stamping, drilling. Thanks to this method, it is possible to obtain the desired part with the required dimensions and shape from a straight sheet or block. With the help of mechanical action, you can achieve the necessary qualities of the material. Often this method is used when it is necessary to make a workpiece suitable for further technological operations.

Types of metal cutting processing are represented by turning, drilling, milling, planing, chiselling and grinding. Each process is different, but in general cutting is the removal of the top layer of the working surface in the form of chips. The most commonly used methods are drilling, turning and milling. When drilling, the part is fixed in a stationary position and is impacted with a drill of a given diameter. During turning, the workpiece rotates and the cutting tools move in specified directions. When using the rotational movement of the cutting tool relative to a stationary part.

Chemical processing of metals to increase the protective properties of the material

Chemical treatment is practically the simplest type of impact on a material. It does not require much labor or specialized equipment. All types of chemical processing of metals are used to give the surface a certain appearance. Also, under the influence of chemical exposure, they strive to increase the protective properties of the material - resistance to corrosion and mechanical damage.

Among these methods of chemical influence, the most popular are passivation and oxidation, although cadmium plating, chrome plating, copper plating, nickel plating, galvanizing and others are often used. All methods and processes are carried out with the aim of increasing various indicators: strength, wear resistance, hardness, resistance. In addition, this type of processing is used to give the surface a decorative appearance.

Above we discussed indicators characterizing the quality of parts due to their intended purpose in the machine. Economic achievement of quality of parts is one of the main tasks of mechanical engineering technology.

The most economical, apparently, would be such a technological process, as a result of which the raw product of nature would directly produce a finished part that meets its intended purpose.

The practice of mechanical engineering at the present stage of development does not have such processes, and therefore parts are made from various types of semi-finished products.

Thus, in mechanical engineering, the manufacture of parts consists of transforming a selected semi-finished product into a finished part. From the point of view of achieving the required accuracy of a part, the task comes down to choosing the required volume of a semi-finished product, giving it a shape and size that is close to the future part, and “refining” them to deviations limited by tolerances for the finished part.

1. Manufacturing of blanks machine parts are produced:

a) metal casting in various ways;

b) processing of metals by pressure (plastic deformation), forging, stamping (hot and cold), pressing (extrusion), rolling, drawing;

c) plastic molding;

d) stamping of plastics.

2. Workpiece processing machine parts are produced:

a) mechanically:

Removing chips - cutting metal with blade tools and abrasives on metal-cutting machines;

Plastic deformation (without removing chips) – metal compaction; rolling and rolling with rollers, punching - calibration of holes with a ball or mandrel; rolling (to obtain a corrugated surface);

Cold straightening of metal parts;

shot blasting of metal parts;

plastic deformation of plastics.

b) chemical-mechanical methods :

Finishing (grinding) with laps made primarily of cast iron, copper or brass, micropowders and pastes. The lap material is usually softer than the material of the workpiece;

Polishing with soft circles (from cloth, calico, felt, paper, leather) using polishing pastes containing (like lapping pastes) surfactants that chemically affect the material being processed;

Processing (sharpening and finishing) of a carbide tool in a solution of copper sulfate using abrasive powder and a metal disc.

c) electrochemical methods, the essence of which is the use of electrical energy in the form of electrolysis.

d) thermal methods, which are used to modify the structure of the metal to obtain its mechanical and physical properties that meet technical requirements.

d) X imico-thermal processing methods are used for metal parts in order to improve their physical, chemical and mechanical properties - increase their heat resistance, wear resistance, etc. by changing the chemical composition of the surface layer of the metal, which is artificially saturated with nitrogen (the process is called nitriding), aluminum (alitizing), carbon and nitrogen simultaneously with subsequent hardening (cyanidation) and some other elements. This also sometimes includes the widespread process of heat treatment - saturation of low-carbon steel with carbon followed by hardening (cementation).

3. Aging of parts blanks. Aging aims to bring the structure of the casting into a state of equilibrium, i.e., to free the workpiece from internal stresses that arise both during the solidification of the metal and during preliminary mechanical processing (grinding).

Aging happens natural And artificial. The natural aging method is that the blank after casting or after peeling is kept in the open air under the influence of the atmosphere for 0.5-6 months or more.

Due to the duration of this process, the method of artificial aging is more often used. Artificial aging is mainly carried out by heat treatment of the workpiece by heating it in a furnace (electric, gas, oil) at a temperature of 450-500 ° C, holding for 12-15 hours and cooling for 2.5-3 hours together with the furnace, after which the workpiece is finally cooled in air.

Aging is used primarily for large cast parts that require the greatest possible stability of shape and size, for example, for the beds of metal-cutting machines.

4. Metal welding– one of the ways to connect metal parts; is divided into chemical (gas, thermite, etc.) and electrical (electric arc, contact, etc.). Welding can replace soldering, riveting, forging, casting; in many cases, with the help of welding, significant savings in metal are achieved (the labor intensity of manufacturing products is reduced, production is cheaper).

5. Balancing parts. To avoid vibration, parts rotating at high speeds must be balanced. A rotating part will be balanced or balanced when its center of gravity and main axis of inertia coincide with the axis of rotation. The reasons for the unbalance of parts and assemblies may be inhomogeneity of the material, inaccuracy in the size and shape of surfaces, asymmetrical arrangement of the metal mass relative to the axis of rotation, mismatch of the axes of mating parts rotating together.

Parts that perform reciprocating motion (for example, a piston with a connecting rod in an internal combustion engine) are adjusted according to weight (mass).

6) Cleaning, rinsing and coating parts with lubricant. During processing and after processing, parts are cleaned, washed, dried and coated with lubricant. Cleaning is carried out by mechanical or chemical methods, washing - in washing tanks or washing machines, drying - by blowing with compressed air. Parts are coated with lubricant to protect them from corrosion.

The most common method of manufacturing parts is associated with removing a layer of material, resulting in a surface with purity, the magnitude of which depends on the technology and processing modes.

Type of processing with removing a layer of material is indicated by a sign in the form of the Latin letter “V” which consists of three segments, two of which are shorter than the third and one of which is located horizontally.

Machining has become widespread in all branches of industrial production associated with the shaping of the geometric dimensions of various materials, for example: wood, metals and alloys, glass, ceramic materials, plastics.

The essence of the processing process with the removal of a layer of material is that, using a special cutting tool, a layer of material is removed from the workpiece, gradually bringing the shape and dimensions closer to the final product in accordance with the technical specifications. Processing methods cutting are divided into manual processing and machine processing. With the help of manual processing, the material is finished using tools such as a hacksaw, file, drill, chisel, needle file, chisel and much more. The machines use cutters, drills, milling cutters, countersinks, countersinks, etc.

In mechanical engineering, the main type of processing is cutting process on metal-cutting machines, which is carried out in accordance with the technical specifications.

The most common types of cutting materials are: turning and boring, milling, grinding, drilling, planing, broaching, polishing. Universal lathes and milling machines, drilling machines, gear cutting and grinding machines, broaching machines, etc. are used as equipment for processing materials by cutting.

The roughness of the surface also determines strength of parts. The failure of a part, especially under variable loads, is explained by the presence of stress concentrations due to its inherent irregularities. The lower the degree of roughness, the less likely it is for surface cracks to occur due to metal fatigue. Additional finishing types of parts processing

Improving the quality indicators of surface roughness significantly increases the anti-corrosion resistance of the surfaces of parts. This becomes especially true in the case where protective coatings cannot be used for working surfaces, for example, on the surface of the cylinders of internal combustion engines and other similar structural elements.

Proper surface quality plays a significant role in connections that meet the conditions of tightness, density and thermal conductivity.

As surface roughness parameters decrease, their ability to reflect electromagnetic, ultrasonic and light waves improves; losses of electromagnetic energy in waveguides and resonant systems are reduced, capacitance indicators are reduced; In electric vacuum devices, gas absorption and gas emission are reduced, and it becomes easier to clean parts from adsorbed gases, vapors and dust.

An important relief characteristic of surface quality is the direction of traces remaining after mechanical and other types of processing. It affects the wear resistance of the working surface, determines the quality of fits, and the reliability of press connections. In critical cases, the designer must specify the direction of processing marks on the surface of the part. This may be relevant, for example, in connection with the direction of sliding of the mating parts or the method of movement of liquid or gas through the part. Wear is significantly reduced when the sliding directions coincide with the direction of the roughness of both parts.

Meets high precision requirements roughness with a minimum value. This is determined not only by the conditions in which the mating parts are involved, but also by the need to obtain accurate measurement results in production. Reducing roughness is of great importance for matings, since the size of the gap or interference obtained as a result of measuring parts of the parts differs from the size of the nominal clearance or interference.

In order for the surfaces of parts to be aesthetically beautiful, they are processed to obtain minimum roughness values. Polished parts In addition to their beautiful appearance, they create conditions for the convenience of keeping their surfaces clean.

People who process metal parts using cutters for a metal lathe and tool sellers know very well what types they are divided into. Those who occasionally use metal turning tools often have difficulty choosing the right option. After studying the information presented below, you can easily choose the metal-cutting device that suits your needs.

Design features

Each metal turning tool consists of the following main parts:

• holder. Designed for fixation on a turning device;
• working head. Used for processing parts.

The working head of a metal-cutting device contains various planes and edges. Their sharpening angle depends on the characteristics of the steel from which the part is made and the type of processing. The cutter holder for a metal lathe usually has a square or rectangular cross-section.

Structurally, it is possible to distinguish the following types of cutters:

1. Direct. The holder and head are either on the same axis or on two axes that lie parallel.
2. Curved. The holder has a curved shape.
3. Bent back. If you look at the top of such a tool, you will notice that its head is bent.
4. Retracted. The head has a smaller width than the holder. The axes either coincide or are shifted relative to each other.

Varieties

The classification of turning tools is regulated by the rules of a certain standard. According to its requirements, these devices are divided into the following groups:

1. Solid. Made entirely of alloy steel. There are devices that are made from tool steel, but they are not often used.
2. Devices on the working element of which carbide plates for turning cutters are soldered. The most common at present.
3. Turning cutters with replaceable inserts made of hard alloys. The plates are attached to the head with special screws and clamping devices. They are not used as often as other types of models.

Besides, devices differ in the direction of feeding. They can be:

• Left. The serve goes to the right. If you place your left hand on top of the tool, the cutting edge will be near the thumb, which is bent.
• Right. They are used most often, the feed goes to the left.

The types and purposes of turning cutters form the following classification:

• carrying out finishing processing of the product;
• rough processing (grinding);
• semi-finishing;
• execution of operations that require high precision.

Whatever category the metal-cutting tool is from, it the plates are made of carbide materials: VK8, T5K10, T15K6. T30K4 is occasionally used. Nowadays there are many types of turning tools.

Direct passes

Pass-through lathe cutters have the same purpose as the bent version, but it is better to cut chamfers with a different device. They usually process the outer surfaces of steel parts.

The dimensions, or more precisely, their holders, can be as follows:

• 25×16 mm – rectangle;
• 25×25 – square (these models are used for special operations).

Bent pass-throughs

These types of turning cutters, the working head of which can be bent to the left/right, are used for processing the ends of parts. In addition, they can be used to cut chamfers.

The holders have the following standard sizes:

• 16×10 – educational devices;
• 20×12 – non-standard size;
• 25x16 is the most commonly used size;
• 32×20;
• 40×25 – with a holder of this standard size, they are usually produced to order; they are almost impossible to buy in a store.

All requirements for mechanical turning tools are specified in state standard 18877-73.

Thrust pass-throughs

These types of turning cutters can have a straight or bent head, however, this design feature is not taken into account in the marking. They are simply called persistent pass-throughs.

This device, with the help of which the surface of cylindrical metal parts is processed on a machine, is the most popular type of cutting equipment. The design makes it possible to remove a large amount of excess metal from the workpiece in one pass. Processing is carried out along the axis of rotation of the part.

The holders of persistent turning cutters are available in the following standard sizes:

• 16×10;
• 20×12;
• 25x16;
• 32×20;
• 40×25

Bent edges

It looks similar to the pass-through blade, but has a different cutting blade shape (triangle). Using such tools, parts are processed in a direction that is perpendicular to the axis of rotation. In addition to bent ones, there are persistent trimming devices, but they are rarely used.

The standard sizes of the holders are as follows:

• 16×10;
• 25x16;
• 32×20

Cut-off

The turning cutter is very common nowadays. According to its own name, it is used to cut parts at an angle of 90 degrees. It is also used to make grooves of different depths. It’s quite easy to understand that you have a cutting tool in front of you. It has a thin leg with a carbide plate soldered onto it.

Depending on the design, there are left- and right-handed cutting devices. It is not difficult to distinguish them. You need to turn the tool over with the cutting blade down and look at which side the leg is on.

The holder sizes are as follows:

• 16×10 – educational equipment;
• 20×12;
• 20×16 – the most common;
• 40×25

Threading machines for external threads

The purpose of these devices is to cut threads on the outside of the part. Usually they make metric threads, but if you change the sharpening, it is possible to create a different type of thread.

The cutting blade that is installed on this tool has the shape of a spear. Materials for turning cutters are carbide alloys.

Threading machines for internal threads

This tool can only make a thread in a large hole. This is due to the design features. In appearance it looks like a boring device for processing blind holes. However, these instruments should not be confused. They vary significantly.

Holder dimensions:

• 16x16x150;
• 20x20x200;
• 25x25x300

The holder has a square-shaped cross-section. Standard sizes can be determined by the first two numbers in the marking. Number 3 – holder size. The depth to which it is possible to cut threads in the internal hole depends on it.

These tools can only be used on devices equipped with a guitar (special device).

Boring for blind holes

The plate has the shape of a triangle. Purpose – processing of blind holes. The working head is bent.

Standard sizes:

• 16x16x170;
• 20x20x200;
• 25x25x300

The largest radius of a hole that can be machined using a boring cutter depends on the size of the holder.

Boring machines for through holes

The tools are intended for processing through holes that are created during drilling. The depth of the hole that can be created on the device depends on the size of the holder. The layer of material removed during the operation is approximately equal to the bend of the head.

Today in stores there are boring tools of the following sizes:

• 16x16x170;
• 20x20x200;
• 25x25x300

Prefabricated

When it comes to the main types of turning tools, it is necessary to mention prefabricated ones. They are considered universal because they can be equipped with cutting blades for different purposes. For example, by fixing cutting inserts of different types on one holder, it is possible to obtain tools for processing metal parts on the device at various angles.

Typically, prefabricated cutters are used on numerically controlled devices or on special equipment. They are intended for turning contours, boring blind and through holes, and other turning operations.

When choosing a tool that will be used to process metal parts on a special device, you need to pay special attention to the elements of the turning cutter. The holder and working head are the most important parts of the cutting device. It depends on them how well the steel workpiece will be processed and what size holes can be made. If you choose the wrong working tool, you may encounter various difficulties when processing a metal part. It is recommended to study the classification and understand what this or that product is intended for. Based on the knowledge gained, you will be able to make the right choice of metal-cutting equipment.

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