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Presses for cold and hot stamping of sheet metal. Drawing Stamping with ductile metal

Sheet stamping is now actively used for the production of a wide range of products by many industrial sectors related to the metal processing process.

1

Stamping of parts from sheet metal - this process refers to the production of finished products, various parts and semi-finished products from metals by deforming the raw materials under pressure.

Our distant ancestors knew similar technology, who, through elementary stamping, made weapons, all kinds of jewelry and household items.

Since the 1850s, the described type of processing began to be modernized and technically improved, which made it possible to mass-produce a variety of products for mass demand by stamping. Moreover, the finished stamped products were distinguished by quite high quality and excellent performance characteristics.

With the advent of the 20th century, sheet stamping of metal products reached a completely new production and technical level. Thanks to it, the automobile production sector began to develop (vehicle bodies and many other parts were made from stamped material). In the 1930s, stamping was adopted by shipbuilding and aircraft manufacturing enterprises, and after a couple of decades it became indispensable for the needs of rocketry.

Stamped metal structures are characterized by a number of special properties, which, in principle, determined the popularity of the technology in question. Its advantages include the following features:

  • mechanization and automation of production processes, which are achieved through the introduction of powerful rotary conveyor lines of equipment;
  • production of any geometric parameters and shapes of ready-to-use products and various semi-finished products;
  • production of high-precision dimensional parts that interchange each other without the need for additional processing using cutting tools and equipment.

In addition, hot and cold stamping guarantees the production of relatively “modest” metal products with rational shapes and high strength parameters. Sheet stamping operations make it possible to produce both massive blanks for shipbuilding, machine and automotive enterprises, and thin-walled, literally filigree parts (for example, thin hands for watches).

It is also impossible not to note separately the high productivity of the sheet stamping operation and the possibility of obtaining, when used in conjunction with welding operations, all-in-one type assemblies of any size, which production industries such as shipbuilding and carriage building cannot do without.

2

The starting raw materials for the technological operation are steel strips, thin strips or sheet metal. Depending on the type of processing, stamping is of two types: cold; hot. In most cases, cold stamping is used. In cases where the power and productivity of stamping equipment is low, as well as when the workpiece has low plasticity, hot stamping is recommended. Usually, material with a thickness of no more than five millimeters is processed hot.

The technological process of stamping is usually divided into the following operations: separation; shape-changing. Separating ones are necessary to separate the deformed section of a metal product along a certain contour during the process of shearing the material. These operations include:

  • Cutting: separating a part of a workpiece along a straight or curved line (the process is performed sequentially). Cutting is carried out using guillotine, disk, vibrating and other types of shears when it is necessary to cut metal sheets into strips of the required sizes, as well as in the manufacture of ready-to-use products.
  • Punching. It is used when it is necessary to obtain holes of different shapes in the workpiece.
  • Cutting down. This operation allows you to create a part that has a closed contour.

But form-changing operations are carried out to modify (without the phenomenon of destruction) the geometric dimensions and configuration of the workpiece. These include:

  • Beading: creating edges of specified sizes around the holes and along the contour (outer) of the product. Flanging, as a rule, is performed at the ends of pipe structures, to which flanges are subsequently planned to be attached.
  • Drawing: obtaining spatial hollow products (hemispherical, conical, cylindrical, box-shaped, etc.) from initial flat blanks.
  • Crimping: narrowing the ends of hollow and three-dimensional metal parts using a conical matrix.
  • Bending: giving a curved configuration to flat parts.
  • Forming: the outer contour of the workpiece remains unchanged, but its local shape changes according to the specified parameters.

Cold stamping involves the use of copper and aluminum alloys (as well as pure copper and aluminum sheets), alloyed and. Materials from the group of non-metals are often used - plastic, leather, thick cardboard and others.

It seems important that cold metal processing ensures a sufficiently high quality of the surface of the resulting semi-finished products or finished parts. Their purity can in some cases reach class 8. Although consumers usually do not make such demands on stamped steel, they are quite satisfied with surface cleanliness at the level of 2–6 classes.

Note that cold stamping of sheet materials increases the specific strength of the finished parts, which distinguishes it better from standard rolled metal. But when stamping, it is very important to study and take into account all the features of the material that is used to produce a particular product. In order for cold stamping to take place efficiently, it is necessary to take into account the following characteristics of the feedstock:

  • magnetic and electrical conductivity;
  • hardness, mechanical strength;
  • mass;
  • impact strength;
  • heat resistance and thermal conductivity;
  • durability, ability to resist corrosion and operational wear.

3

Sheet stamping is done in special dies made from. In most cases, they have a moving and a fixed part in which a punch and a matrix (working components of the die) are mounted. When these parts come together, the sheet material becomes deformed. Using a special press, the fixed and moving parts are fastened. The second is fixed in the actuator, and the first is on the table on which the press is located.

As was said, dies (or rather their working elements) are made from expensive tool alloys. But in cases where soft metals (for example, copper or aluminum) are stamped, you can save on stamp material by using wood pressed into dense rolls or plastic.

You can also reduce the cost of stamping large-sized products that are manufactured in small batches by making a matrix from concrete or cast iron. In this case, a container with water is used as the second part of the stamp (punch). It is placed above the workpiece on the matrix. Then, in water, by detonating a charge of gunpowder (or exposure to an electric discharge), the required pressure is created, which deforms the sheet of metal according to the shape specified by the matrix.

The main equipment for stamping is a press and shears. Using scissors, the material is cut. Nowadays, vibrating shears are most often used, characterized by ease of operation and sufficient functionality. But the stamping press is chosen depending on what operations are being carried out. Typically, a crank press is used, which can be four-, two-, or single-crank. It works on a fairly simple principle:

  • the engine, using a V-belt drive, transmits the necessary movement through the clutch to the crank shaft;
  • a connecting rod adjustable in length transmits the movement further (to the slider of the crank device);
  • The press is launched into the working stroke through the clutch by a pedal.

To process simple parts, simple devices are used. But for stamping truly complex products, a special type of press is used, which is equipped with several sliders.


One of my favorite areas in jewelry art is all kinds of precious bottles. For one of them, several years ago, a simple device was made for drawing out the rectangular half of the body. Allowing hand-to-hand combat without machines. press sheet metal into a convenient base for the product.

A rectangle of the required dimensions (thickness 5.5 mm) is cut out of thick sheet metal. Then the edges and corners are littered. Sanded it. Screwed it to a thinner plate. This is the punch:

Using the first rectangle as a template, a matrix frame is made of the same thickness, with a hole size of 1 mm plus relative to the first part:


The inner edge of the hole is carefully processed. The rib around which the stamped metal will bend and flow is heaped to a small radius and polished even more thoroughly than the first part (with a drill, rubber-abrasive discs).
Now we take 0.5 mm brass, with a decent allowance relative to the size of the hole, and start hammering. You can press with a medium-sized vice, but I simply hit with a heavy hammer. Not immediately, with intermediate annealings. First cycle:


I annealed it and straightened out the wrinkles that were trying to form. Second cycle:


Here, pay attention, it is clearly visible that the formation of the box is not due to stretching and thinning of the metal. Well, of course it stretches a little at the corners, but basically, the metal from the allowance is pulled into the mold. Therefore, the allowance should not be large and not small, ideally so that most of the allowance is retracted, leaving another 2-3 mm for subsequent trimming. That is, in my picture the seam allowance is too large, especially on the short side of the rectangle.
But on the other hand, if the allowance is too small, then when tightened, wrinkles and folds form, that is, in fact, a wide allowance still plays an important stabilizing role.
Third pass. Finish, punch and die are closed:


I cut off the stamp waste. To make the body thicker, I grab about a millimeter extra and straighten the walls on a small anvil:


The walls are straightened, but incorrectly deformed corners remain:


From the back, non-working part of the turning tool, I make a “horn” on which these angles can be cut:


Corners are molded:


I file the mating edges to a plane, connect and solder. To avoid a bomb, I first solder it at four points, at the corners. And I drill a hole:


After this, you can solder the entire perimeter. And then all you need is a burner, refueling station, etc. bells and whistles:




Finished lighter:


I twirled it in my hands, played with it this way and that, and realized what was missing. Improved grip when pulling the cap upwards. I took it apart and soldered this “coil”:


Now, it’s very convenient to take on it:


And it echoes and balances the wheel of the chair.


We are burning:


And here, in fact, is the silver project for which this matrix was started. Pendant bottle:


Thank you for your attention.

Modern progress does not stand still and every year both new and existing techniques for processing various materials appear and are modernized. Stamping of metal parts is far from a new operation, the quality and accuracy of which directly depends on the equipment and devices used. It is innovative methods and modern machines that are the basis for high-quality and prompt execution of orders of any complexity.

JSC ELTEZA offers professional production of stamped metal parts. High-tech equipment and production facilities of our enterprise provide the ability to promptly fulfill orders of any complexity. We will always be happy to ensure that work can be completed quickly and that we guarantee the quality of every part produced. Modern sheet stamping is one of the advanced methods for producing various parts from sheet metal, which allows you to obtain the required result as quickly as possible and at minimal cost.

Technology for the production of stamped parts

Metal stamping involves a set of technological stages, the result of which is the required part. A very important parameter in this case is the consistency of equipment operation and the most accurate control of parameters when performing each process. Stamping of parts can be represented in the form of the following operations:

  • metal cutting to ensure the optimal size of each workpiece;
  • metal bending allows you to change the shape of the workpiece in the radial area;
  • the forming process is designed to provide the desired shape while maintaining the basic contours of the part;
  • crimping involves the use of dies designed to narrow individual parts of the workpiece;
  • drawing the part is a mandatory element to achieve the maximum flatness of the product;
  • flanging parts involves pressing the metal in a circle, expanding its diameter. This process is especially important in the manufacture of clamps, bends and flanges.

Thus, we can safely say that sheet metal stamping of parts is a complex, diverse process that may require a large number of different equipment and highly qualified personnel.

Note: manufacturing parts using this technology requires the design and manufacture of special technological equipment for production

Advantages of manufacturing parts by stamping

Modern stamping of sheet metal parts has many advantages over similar methods of processing materials. These include:

  • the ability to process materials and manufacture parts of minimal weight, with increased requirements for the level of rigidity;
  • the ability to obtain a part of maximum accuracy;
  • all processes are performed on automated equipment, which eliminates the possibility of error due to the human factor;
  • the ability to ensure high productivity and the customer receiving large quantities of goods in the shortest possible time.

These advantages make the production of parts using stamping one of the most profitable and affordable solutions for any enterprise.

Professional stamping services for parts in Moscow

JSC ELTEZA offers to order metal stamping on the most favorable commercial terms. We are always ready to accurately reproduce the requirements of each customer and guarantee the quality of execution of any part, regardless of the complexity and size of the batch. Our stamping of sheet metal parts in Moscow is in demand among both large companies and small organizations, and the prices we offer are among the most affordable in the region.

Since ancient times, people have made thin-walled products, vessels and jewelry from metal. They were made from a sheet of metal by hammering - giving shape to a cold or heated sheet of ductile metal by tapping it with a hammer around a wooden model of the future product. The seams were soldered or embossed. Copper was most often subjected to this treatment, less often silver or gold. The products obtained in this way were extremely highly valued, since all operations were manual and it took the craftsman more than one day to make one jug.

The inquisitive human mind was looking for ways to speed up and reduce the cost of production until the mid-19th century, when such a powerful source of energy as steam appeared. Since then, the technology for producing thin-walled metal sheet products by deforming it under pressure, or sheet stamping, has improved significantly. Today, billions of different parts are produced using this method, from phone parts to car bodies.

Cold sheet stamping is a guarantee of high-precision parts

Sheet metal stamping from sheet metal at room temperature is called cold stamping. It is used for small sheet thicknesses and in the case of ductile alloys. If they are stamped from a thick sheet (from 5 mm) or from alloys with low fluidity, then the workpiece sheet is heated to increase ductility.

Sheet stamping guarantees the production of a large number of parts that are absolutely identical in shape and size with high accuracy.

Cold die forging makes it possible to produce high-precision thin-walled parts of almost any shape at a cost significantly lower than in the case of casting or machining. The metal utilization rate is also much higher. In addition, cold die forging guarantees not only strength, but also uniformity of the material properties of the part, which is especially important in critical structures.

Both die stamping and sheet metal stamping are cost effective for large production runs. This is due to the high costs of preparing production.

Characteristics of sheet stamping

Cold sheet stamping is today one of the most widespread technologies for processing metals, plastics and some other materials. The range of application of the technology is from large structures in shipbuilding to thin-walled parts of household appliances

The technology is characterized by the following undeniable advantages:

  • Exceptional opportunities for mechanization and automation of production processes.
  • Reducing the cost of manufacturing mass products.
  • High utilization of sheet metal.
  • The ability to accurately manufacture thin-walled but durable products of almost any shape.
  • Minimal need for subsequent machining.

However, in addition to obvious advantages, cold sheet metal stamping also has disadvantages. This is, first of all:

  • High complexity of technological process design.
  • High cost of preparation for production of molds.
  • Highly qualified press equipment debuggers.

It should be noted that with large series of manufactured products, these disadvantages are leveled out due to the economies of scale known from economics, and the cost of manufactured products turns out to be lower than with alternative methods of metal processing.

Types of sheet metal stamping equipment

A wide range of equipment is used for different types of sheet metal stamping operations.

Thus, vibration or guillotine shears are used for cutting operations.

To perform forming operations, the main stamping equipment is used - a sheet stamping machine or a press. By type they differ in:

  • Crank-rod.
  • Hydraulic.
  • Radial forging.
  • electromagnetic.

The simplest to set up and maintain is a press with a crank drive. It is suitable for simple sheet stamping—thin-walled, small and medium-sized parts of simple shape.

Hydraulic presses allow you to develop much greater force (up to 2 thousand tons) and more accurately regulate the press stroke. This type of equipment is used for bending or die stamping operations from thick sheets.

Radial forging complexes are used for sheet stamping of parts having the shape of a body of rotation.

Electromagnetic presses are a fairly new type of equipment. The pressure on the workpiece is produced by the mass of the electromagnetic core, directed to the punch by an electromagnetic pulse. A pulse of opposite polarity returns the core to its original position. Such a drive is much simpler to manufacture and maintain than a hydraulic one, but does not yet reach its power.

Principle of operation

The physical principle of operation of stamping equipment is the plastic deformation of a sheet blank under pressure. The shape of the future part is determined by two parts - a matrix and a punch, which are pressed against the sheet blank from both sides under great pressure. Where there is a convexity at the matrix, the punch has a depression corresponding to it in shape and size. When deformed, the sheet blank repeats the shape of the matrix and punch.

Along with this, holes can be drilled and individual parts can be cut out of the sheet material. When designing a technological process for cold stamping of sheet metal parts, the tooling designer and technologist combine and, if possible, combine form-changing separation operations in order to make do with a minimum number of workers passing the die and thus reduce the cost of manufacturing the product.

In the case of thin sheets, cold sheet stamping is carried out. When working with thick sheets or low-ductility alloys, the workpiece is preheated to increase its ductility.

What operations does cold stamping involve?

All working operations of cold sheet stamping are divided into two large groups: separation and forming.

Separation operations of sheet stamping include operations associated with violating the integrity of the sheet material. The most common of them are

  • Cutting is the separation of part of a workpiece along a straight or curved line. It is used both for obtaining finished products and for dividing sheets into blanks of the required size for the purpose of further processing.
  • Cutting-separation of part of the workpiece along a closed contour. A piece of metal can also be cut out inside the contour.
  • Punching is the production of round or arbitrary shaped holes in a workpiece.

Shape-changing operations of sheet stamping include operations that change the spatial shape of the sheet without violating its integrity, such as:

  • Bending - giving a flat workpiece a curved shape along the longitudinal axis. There are V-shaped, U-shaped and more complex bending forms.
  • Drawing is the transformation of a flat workpiece into a hollow spatial form. When drawing, the thickness of the workpiece may change.
  • Beading is the creation of edges along the outer or inner contour of a product.
  • Crimping is the compression of the workpiece material in a conical die in order to reduce the size of the end part of the part.
  • Molding - Changing the shape of a part of a part while maintaining the outer contour line.

When designing sheet metal stamping technology, the technologist combines operations from both groups.

Process technology

The process of cold sheet stamping begins with the joint work of the technologist and the tooling designer. They consider all the changes that must occur with a flat workpiece on its way to the finished product, plan and group separating and forming operations. After such grouping, the operations performed during each pass of the press are determined (if the part cannot be stamped in one pass). For this specific list of operations, a matrix-punch pair is designed.

Matrices and punches are usually produced by milling on multi-axis machining centers. The accuracy of the stamping dimensions and the final quality of the product directly depend on the accuracy of manufacturing. The materials used are high-alloy steel - the mold must withstand hundreds, or even millions of stamping cycles without changing in size. Often molds are made consisting of several parts, which are then securely connected.

Sometimes an insert made of a stronger material is installed in the mold, for example, in the part where cutting or drawing will be carried out and which will be subject to significantly greater stresses than the rest of the mold.

An extremely important stage of the technology is setting up presses for sheet stamping. Each working pass of the press requires strict adherence to the force prescribed by the technology in order, on the one hand, to accurately shape the workpiece, and, on the other hand, not to damage it.

Progressive methods of sheet metal stamping

Rubber stamping. Used for workpieces of small thickness and high ductility. The role of the matrix or punch is performed by hard rubber. It simplifies the production of the punch and is suitable for small series of stampings.

Liquid stamping. The role of the punch is played by liquid supplied under pressure. It presses the workpiece against the die and forces the sheet to exactly follow its shape. The method is used for drawing products of complex spatial shape.

Explosion stamping. A small explosive charge is detonated in a protected chamber. The resulting high pressure forces the workpiece into the die. The method is used for large parts and intricate configurations that are difficult to manufacture otherwise. Significant savings in equipment costs are achieved.

Electrohydraulic sheet metal stamping

Electrohydraulic stamping. The role of mechanical pressure is played by a shock wave in the liquid, which is caused by a high voltage discharge. The method is highly accurate and cost-effective.

Magnetic pulse stamping. High-intensity magnetic pulses generate a high-energy magnetic field that impacts the workpiece, inducing eddy currents in it and forcing it into a given shape. In this way, pipes are compressed and complex reliefs are formed.

Unlike previous methods related to cold die forging, this method is a combination of two technologies: stamping and casting. First, the required volume of molten metal is poured into the matrix, after which the punch is lowered into it.

Liquid metal is extruded into the gap between the matrix and the punch, which is the shape of the future product. The method is used in the manufacture of large thin-walled housing parts made of low-melting and ductile alloys.

Sheet stamping– one of the types of cold pressure treatment, in which sheet material is deformed in a cold or heated state.

Sheet stamping produces a variety of flat and spatial parts - from small ones, weighing from fractions of a gram and measuring fractions of a millimeter (seconds hand of a watch), to medium-sized (metal utensils, lids, brackets) and large (facing parts of cars).

The thickness of the workpiece during sheet stamping is usually no more than 10 mm, but sometimes it can exceed 20 mm; in this case, stamping is carried out with preheating to forging temperatures.

When sheet stamping is used: low-carbon steels, ductile alloy steels, non-ferrous metals and alloys based on them, precious metals, as well as non-metallic materials: organic glass, felt, celluloid, textolite, felt, etc.

Sheet stamping is widely used in various industries, especially in the automotive industry, rocketry, aircraft manufacturing, instrument making, and the electrical industry.

The main advantages of sheet stamping:

    the ability to manufacture durable, lightweight and rigid thin-walled parts of simple and complex shapes, which are impossible or difficult to obtain by other means;

    high dimensional accuracy and surface quality, allowing to reduce machining to a minimum;

    comparative simplicity of mechanization and automation of stamping processes, ensuring high productivity (30,000...40,000 parts per shift from one machine);

    good adaptability to the scale of production, in which sheet stamping can be economically beneficial in both mass and small-scale production.

Cold sheet stamping consists of performing separation and form-changing operations in a certain sequence, through which the original blanks are given the shape and dimensions of the part.

Sheet stamping operation is the process of plastic deformation that provides a characteristic change in the shape of a certain section of the workpiece.

Distinguish dividing operations in which the stage of plastic deformation necessarily ends in destruction, and formative operations in which the workpiece should not be destroyed during deformation. When designing a technological process for manufacturing parts by sheet stamping, the main task is to select the most rational operations and the sequence of their use, which makes it possible to obtain parts with specified performance properties at minimal cost and good working conditions.

All operations are performed using special tools - stamps, which have different designs depending on their purpose. Dies consist of working elements - a matrix and a punch, and auxiliary parts - clamps, guides, stops, etc. The punch is pressed into or enclosed by the deformable metal, and the die encloses the shape-changing workpiece and the punch.

Sheet forming operations

Separation operations are intended either for obtaining a workpiece from a sheet or tape, or for separating one part of the workpiece from another. Operations can be performed along a closed or open loop.

The separation of one part of the workpiece from another is carried out by a relative displacement of these parts in a direction perpendicular to the plane of the workpiece. This displacement is initially characterized by plastic deformation and ends with destruction.

Segment– separation of part of the workpiece along an open contour using special machines – scissors or stamps.

It is usually used as a procurement operation for dividing sheets into strips and blanks of the required size.

The main types of scissors are shown in Fig. 15.5.

Rice. 15.5. Schemes of operation of scissors: a – guillotine; b – disk

Scissors with translational movement of the cutting edges of the knife can be with parallel knives, for cutting narrow strips, with one inclined knife - guillotine (Fig. 15.5.a). The cutting edges in guillotine shears are inclined to each other at an angle of 1...5 0 to reduce the cutting force. The sheet is fed until it stops, which determines the width of the strip to be cut IN. The length of the cut strip L should not exceed the length of the knives.

Scissors with rotational movement of the cutting edges are disk scissors (Fig. 15.5.b). The length of the cut piece is not limited by the tool. The rotation of the disc knives not only ensures separation, but also feeds the workpiece under the influence of friction forces. The cutting edges of the knives overlap one another, this ensures the straightness of the cutting line. To ensure gripping and feeding of the workpiece, the diameter of the knives must be 30...70 times greater than the thickness of the workpiece, increasing as the friction coefficient decreases.

Felling And punching– separation of metal along a closed contour in a die.

When cutting and punching, the nature of the workpiece deformation is the same. These operations differ only in purpose. The outer contour of the part is formed by cutting, and the inner contour is formed by punching (making holes).

Cutting and punching are carried out with a metal punch and matrix. The punch presses part of the workpiece into the die hole. A diagram of the cutting and punching processes is shown in Fig. 15.6.

The main technological parameter of the operations is the radial gap between the punch and the matrix. The gap is determined depending on the thickness and mechanical properties of the workpiece, it is approximately. When punching, the dimensions of the die hole are equal to the dimensions of the product, and the dimensions of the punch are smaller than them. When punching, the size of the punch is equal to the dimensions of the hole, and the dimensions of the matrix are larger than them.

Rice. 15.6. Scheme of the cutting (a) and punching (b) processes

1 – punch, 2 – matrix, 3 – product, 4 – waste

Reducing the cutting force is achieved by making a bevel on the matrix when cutting, and on the punch when punching.

When stamping small and medium-sized parts, several flat blanks are cut out from one sheet blank for stamping. Between the adjacent contours of the cut-out workpieces, jumpers are left with a width approximately equal to the thickness of the workpiece. In some cases, adjacent workpieces are cut out without jumpers (saving metal while deteriorating the quality of the cut and reducing tool life).

The arrangement of the contours of adjacent cut-out blanks on sheet material is called cutting. The part of the workpiece remaining after cutting is die-cutting.

Die cutting constitutes the main waste in sheet metal stamping. The type of cutting should be selected based on the condition of reducing metal waste in the die cutting (Fig. 15.7).

Fig. 15.7. Examples of cutting material with jumpers (a) and without jumpers (b)

Metal savings can be obtained by: reducing metal consumption for jumpers, using waste-free and low-waste cutting, increasing the accuracy of calculating the dimensions of the workpiece and reducing allowances for cutting