Heat treatment of products. Classification of turning tools for metal

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

The 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.

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:

1. holder with which the tool is fixed on the machine;
2. 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.

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

1. 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;
2. 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.

Metal forming, or metal forming, is possible due to the fact that such materials are characterized by high ductility. As a result of plastic deformation, a finished product can be obtained from a metal blank, the shape and dimensions of which correspond to the required parameters. Metal forming, which can be performed using various technologies, is actively used to produce products used in mechanical engineering, aviation, automotive and other industries.

Physics of metal forming process

The essence of metal pressure processing is that their atoms of such a material, when exposed to an external load, the magnitude of which exceeds the value of its elastic limit, can occupy new stable positions in the crystal lattice. This phenomenon, which is accompanied by metal pressing, is called plastic deformation. During the process of plastic deformation of a metal, not only its mechanical, but also its physicochemical characteristics change.

Depending on the conditions under which OMD occurs, it can be cold or hot. Their differences are as follows:

1. Hot metal processing is performed at a temperature that is higher than its recrystallization temperature.
2. Cold working of metals is accordingly carried out at a temperature below the temperature at which they recrystallize.

Types of processing

The metal processed by pressure, depending on the technology used, is subjected to:

1. rolling;
2. forging;
3. pressing;
4. drawing;
5. processing performed by combined methods.

Rolling

Rolling is a pressure treatment of metal blanks, during which they are exposed to rolling rolls. The purpose of such an operation, which requires the use of specialized equipment, is not only to reduce the geometric parameters of the cross-section of a metal part, but also to give it the required configuration.

Today, metal rolling is carried out using three technologies, the practical implementation of which requires appropriate equipment.

Longitudinal

This is rolling, which is one of the most popular processing methods using this technology. The essence of this method of metal forming is that the workpiece, passing between two rolls rotating in opposite directions, is compressed to a thickness corresponding to the gap between these working elements.

Transverse

Using this technology, metal bodies of rotation are processed by pressure: balls, cylinders, etc. Performing processing of this type does not imply that the workpiece undergoes translational motion.

Cross-helical

This is a technology that is something intermediate between longitudinal and transverse rolling. It is mainly used to process hollow metal workpieces.

Forging

A technological operation such as forging belongs to high-temperature forming methods. Before forging, the metal part is subjected to heating, the magnitude of which depends on the grade of metal from which it is made.

Metal can be processed by forging using several methods, which include:

• forging performed using pneumatic, hydraulic and steam-air equipment;
• stamping;
• forging done by hand.

In machine and hand forging, which is often called free forging, the part, while in the processing zone, is not limited by anything and can take on any spatial position.

Machines and technology for metal forming using the stamping method assume that the workpiece is previously placed in a die matrix, which prevents its free movement. As a result, the part takes exactly the shape that the cavity of the die matrix has.

Forging, which is one of the main types of metal forming, is used mainly in single and small-scale production. When performing such an operation, the heated part is placed between the striking parts of the hammer, which are called strikers. In this case, the role of supporting tools can be played by:

• regular ax:
• crimps of various types;
• rolling out.

Pressing

When performing a technological operation such as pressing, metal is forced out of the matrix cavity through a special hole in it. In this case, the force necessary to carry out such extrusion is created by a powerful press. Parts that are made of metals that are highly brittle are mainly subjected to pressing. The pressing method produces products with a hollow or solid profile from alloys based on titanium, copper, aluminum and magnesium.

Depending on the material of the processed product, pressing can be performed in a cold or hot state. Parts that are made of ductile metals, such as pure aluminum, tin, copper, etc., are not subjected to preheating before pressing. Accordingly, more brittle metals, the chemical composition of which contains nickel, titanium, etc., are subjected to pressing only after preheating as the workpiece itself and the tool used.

Pressing, which can be performed on equipment with a replaceable matrix, allows the production of metal parts of various shapes and sizes. These can be products with external or internal stiffeners, with a constant or different profile in different parts of the part.

Drawing

The main tool with which such a technological operation as drawing is performed is a die, also called a die. During the drawing process, a round or shaped metal blank is pulled through a hole in the die, resulting in a product with the required cross-sectional profile being formed. The most striking example of the use of such technology is the wire production process, which involves a large-diameter workpiece being sequentially pulled through a series of dies, ultimately turning into wire of the required diameter.

Drawing is classified according to a number of parameters. So, it could be:

• dry (if done using soap shavings);
• wet (if a soap emulsion is used to perform it).

According to the degree of cleanliness of the surface being formed, drawing can be:

• rough;
• finishing

Depending on the frequency of transitions, dragging occurs:

• one-time, performed in one pass;
• multiple, performed in several passes, as a result of which the cross-sectional dimensions of the workpiece being processed are gradually reduced.

According to the temperature regime, this type of metal forming can be:

• cold;
• hot.

Volume stamping

The essence of this method of metal forming, such as die stamping, is that the production of a product of the required configuration is carried out using a stamp. The internal cavity, which is formed by the structural elements of the die, limits the flow of metal in an unnecessary direction.

Depending on the design, dies can be open or closed. In open dies, the use of which makes it possible not to adhere to the exact weight of the workpiece being processed, a special gap is provided between their moving parts, into which excess metal can be squeezed out. Meanwhile, the use of open-type stamps forces specialists to remove flash that forms along the contour of the finished product during its formation.

There is no such gap between the structural elements of closed-type dies, and the formation of the finished product occurs in a confined space. In order to process a metal workpiece using such a stamp, its weight and volume must be accurately calculated.

Heat treatment of products promotes softening and better absorption of food by the human body.

In addition, at high temperatures, food is disinfected as a result of the death of microorganisms. The products acquire a pleasant taste and aroma.

However, improper heat treatment can lead to discoloration and the formation of substances in products that have an unpleasant taste and odor, which have a carcinogenic effect. Vitamins and aromatic substances may be destroyed, and the content of soluble nutrients may decrease. Therefore, it is necessary to strictly observe the cooking mode and cooking time.

Cooking

Cooking is the heating of food in a liquid or atmosphere of saturated water vapor. Cooking is one of the main methods of culinary processing, and boiled dishes reign supreme in any national cuisine, especially in medical nutrition.

At cooking using the main method the product is completely immersed in a large amount of liquid (water, milk, broth, syrup, etc.). Before boiling, the process is carried out over high heat in a container with a closed lid; after boiling, the heat is reduced and cooking is continued at low simmer until the product is completely cooked. Full boiling is undesirable, as this quickly boils away the liquid, destroys the shape of the product, and evaporates aromatic substances.

In pressure cookers or autoclaves, excess pressure is created, and the temperature rises to 132 C, which speeds up cooking. When cooking using the main method, a large amount of nutrients are lost from the product due to their transition into a decoction, and the boiled product becomes tasteless. However, if the environmental purity of the product is questionable, cooking in a large amount of water is necessary, since this extracts radionuclides, xenobiotics, etc.

Allowance

Poaching is a more rational type of cooking that allows you to preserve the nutrients of the product as much as possible. In this case, the product is immersed in boiling water by approximately 1/3 of its volume, and 2/3 is cooked with steam with the lid tightly closed. Juicy fruits are poached without adding liquid, in their own juice, released when heated. It is advisable to use poaching, and not cooking, as the main method when preparing vegetable side dishes.

Steaming

Steaming is the main type of heat treatment when preparing second courses for therapeutic diets that require sparing the gastrointestinal tract. To do this, use steam ovens or steam pans with a tightly closed lid. Water is poured into the pan, a grate is placed on the bottom, on which the food is placed.

When the water boils, the pan is filled with steam, in which the food is cooked. The products are juicy, with a delicate texture and well-preserved shape. The loss of nutrients is less than with poaching.

There is another method of steam cooking. Pour up to half boiling water into a large pan, tie a linen napkin around the top of the pan so that it sags slightly in the middle. Food products (most often rice) are placed in a napkin, like in a hammock, and the pan is placed on the fire, and the food in the napkins is covered with an overturned plate. Rice or other grains turn out crumbly, not unsaturated with excess water.

Much less commonly used is the so-called contactless cooking food. With it, there is no direct contact of the environment in which the food is cooked, or even the container itself where the food is located, with fire. This is achieved by placing the vessel (pan, pot, cast iron with a tightly closed lid) with food not on the fire, but in a larger vessel into which water is poured, and this large vessel is placed on the fire (water bath).

Non-contact cooking requires much more heat and time for cooking, but the taste, consistency and aroma of omelettes, meat, fish, and vegetables becomes unusual. If the lid is on the pan with food, and the cauldron of water where it sits is tightly closed with a lid, then the cooking will not be called a water bath, but a steam bath. The food will be cooked by the steam coming from the boiler. The taste of food with these non-contact cooking methods is different.

Frying

Frying is heating a product without liquid, in fat or heated air. As a result of frying, a crust forms on the surface of the product; the products lose some of their moisture due to evaporation, so they retain a higher concentration of nutrients than when boiled.

Fat plays an important role when frying, as it protects the product from burning, ensures uniform heating, improves the taste of the dish and increases its calorie content. Before frying, the fat must be overheated, since only overheated fat does not burn, does not smoke, does not smoke and remains clean from the beginning to the end of cooking.

Pour vegetable oil into a frying pan in a half-centimeter layer and heat it over medium heat, without bringing it to a boil. After 2-3 minutes, the oil will lighten, and after another couple of minutes a white, barely noticeable, but acrid smoke will appear above it. If you throw a pinch of salt into the oil, it will bounce off the surface with a bang. This means that the oil has overheated, excess water, gases, and various impurities have evaporated from it. This oil will not change as it is further heated and will be easier to fry with.

At the time of overheating, you can add some spices (onion, garlic, anise, fennel, dill seeds), which must be removed after 3-4 minutes. Spices fight off the specific odors of fats and give the corresponding aroma. Another way to improve oil is to use a mixture of animal and vegetable fat: sunflower oil and lard, olive oil and chicken fat, beef fat and mustard oil, etc.

There are several types of frying. The most common of them is frying in the main way, in which the product is heated with a small amount of fat (5-10% by weight of the product) at a temperature of 140-150 C. The best utensils for frying on an open surface are frying pans or roasting pans with a bottom thickness of at least 5 mm. In them, the temperature is distributed more evenly, the possibility of sticking and burning of the product is reduced. In recent years, non-stick frying pans have been used.

At deep frying take 4-6 times more fat than the product, heat it to 160-180C and place the product for 1-5 minutes. Frying is carried out in a deep dish (deep fryer), the products are removed with a slotted spoon or a special mesh. The products are covered with an even, beautiful, golden crust, but the temperature inside does not reach 100 C and is often insufficient to bring them to full readiness and destroy all microorganisms. In this regard, after deep frying, the products can be placed in the oven for some time.

At roasting over an open fire the product is placed on a metal rod or placed on a greased metal grid. The rod or grate is placed over hot coals or electric coils in electric grills and grilled. To ensure uniform frying of the product, the rod is rotated slowly. Frying occurs due to radiant heat.

Roasting in a broiler (in the oven)

A shallow dish (baking tray, frying pan or pastry sheet) is greased and food is placed on it, then placed in an oven at a temperature of 150-270 C. From below, the product is heated due to heat transfer, and from above - due to infrared radiation from the heated walls of the cabinet and the movement of warm air.

The process of formation of a crispy crust occurs more slowly than when frying in the main way, as a result of which the products are heated evenly. To obtain a more golden brown crust and increase the juiciness of the finished product during the frying process, the product is turned over, poured with fat or brushed with sour cream and egg.

Frying in a field of infrared rays (IR) carried out in special devices, while frying time is reduced by 2-6 times and the juiciness of the product is better preserved.

Roasting in a microwave field (in microwave ovens) helps reduce the time of heat treatment, the product retains nutrients well, however, with this method of heat treatment, a crispy crust does not form on the surface of the product. Some technologists consider this method of heat treatment to be cooking.

Auxiliary methods of heat treatment include sautéing and blanching. With these methods, the product is not brought to a state of complete culinary readiness.

Sauteing

Sautéing is a short-term frying of a product until half cooked in a small amount of fat (15-20% by weight of the product) at a temperature of 110-120 C without the formation of a crispy crust. At the same time, some of the essential oils, dyes and vitamins pass from the food into fat, giving it the color, taste and smell of the food. Sauteed vegetables, roots, tomato puree and flour are used to prepare soups, sauces and other culinary products.

Blanching (scalding)- this is short-term (1-5 minutes) cooking or scalding with steam, followed by rinsing the food with cold water. Some varieties of vegetables are blanched to remove bitterness (young white cabbage, turnips, rutabaga); preservation of color, taste and consistency of peeled vegetables and fruits (potatoes, apples) during their subsequent processing; to prevent products from sticking together in the broth (scalding homemade noodles); to facilitate mechanical cleaning of sturgeon fish; for partial removal of extractives and purine bases from animal products.

Stewing, baking and frying after cooking are combined methods of heat treatment.

Extinguishing- this is the poaching of a pre-fried product with the addition of spices and aromatic substances. It should be simmered in a tightly sealed container for 45-60 minutes on the stove, then 1-1.5 hours in the oven. At the end of stewing, when the water evaporates, denser or more acidic liquids (sour cream, juice, vinegar, cream, grape wine) should be added, which prevents the dish from burning and improves its taste and consistency. Salt and spices are added at the end to artificially restore the natural taste of the products lost during long stewing.

Baking- this is the frying of a pre-boiled (sometimes raw) product in an oven to form a golden brown crust. Products are baked at 200-300 C, both with the addition of sauces, eggs, sour cream, and without sauces. This type of heat treatment is necessary for diets without mechanical sparing of the gastrointestinal tract, but with a sharp limitation of purine bases (for example, for gout).

Roasting after cooking used for preparing side potatoes, as well as those products that cannot be cooked by frying alone (fried brains, kidneys). In diet, this technique is used to reduce the content of nitrogenous extractives in meat and fish products.