The technological process during which workpieces are processed, which allows to obtain flat or bulk finished products of various shapes and sizes, is stamping. A working tool for this purpose is a stamp that is mounted on a press or other equipment. Stamping is two types of technology, which, depending on the conditions, are carried out hot or cold, and therefore the equipment and technological standards differ from each other.
Categories
In addition to dividing technology into cold and hot methods, stamping is a whole series of categories into which material processing methods are divided. The chosen method most often depends on the purpose of the product, but technological conditions also affect it. For example, there is a way in which part of the workpiece is separated, and this is stamping separation. This also includes punching, chopping, cutting parts. There is a category of operations when hot stamping is used, through which a sheet of metal changes shape. They are also called molding. As a result, parts are subjected to bending, drawing and other procedures.
Cold and hot stamping are implemented using the same principle, which involves the deformation of the material, but otherwise the manufacture of products by these methods has many differences. Pre-heating of parts to certain (and sufficiently high) temperatures is expected mainly at large industrial enterprises, such as, for example, a metal processing plant. This is due to the complexity of such a technological process, a large number of operations that can be performed qualitatively only with accurate preliminary calculation and the high accuracy of the degree of heating of the workpiece.
Hot way
Stamped parts processed using hot technology should be of excellent quality, because, for example, such important things as boiler bottoms and other hemispherical products, including critical elements in shipbuilding, are made of sheet metal of different thicknesses. To heat a metal part, equipment is used that ensures the correct temperature regime.
These devices and furnaces can be plasma, electric or other, there are many of them. Before submitting a hot part to a stamping press, it is necessary not only to calculate the heating rate, but also to develop a detailed drawing of the finished product, where it is necessary to take into account the shrinkage of the metal after cooling.
Cold stamping
Performing cold stamping involves the formation of the product by the pressure that the working elements of the press exert on the workpiece. Such products are not subject to shrinkage, because they are not preheated before. Further mechanical refinement of such products is also not needed after stamping is completed. Stamping methods can be different, while cold is more convenient and cost-effective.
Cold stamping materials are not just carbon or alloy steels. Stamping works successfully on both aluminum and copper alloys. The cold method is carried out mainly using hydraulic presses, and their production is regulated by GOST. Serial models are very diverse, and therefore it becomes possible to choose the right machine for the production of any configurations and sizes of products. Stamps for stamping metals in their equipment are very different from those that work with materials such as leather, rubber, cardboard, polymer alloys and the like.
Separate stamping
One of the most common technological operations is separation stamping, which separates part of the metal from the workpiece. This method is used in almost all manufacturing enterprises. Special tools are installed on the stamping press, which produce cutting, cutting and punching of the material. Thanks to this process, metal parts can be separated even by a curve, even by a straight cut line. Cutting is performed by a variety of devices: guillotine shears, vibrating and disk machines and the like. Cutting is used in order to cut blanks for further processing.
Felling is another technological operation. For example, a stainless sheet of metal needs to be turned into parts with closed contours. Sheet metal by punching provide holes of any configuration. I must say that this process also requires thorough preliminary preparation and a detailed plan, taking into account the geometric parameters of the tool that is used. Otherwise, a quality product may not work. There are a lot of technological operations related to stamping, because it is necessary to change the initial configuration of the parts. This is bending, molding, flanging, drawing and crimping.
Technological operations
The most common operation that changes the shape of a part is bending, which forms planned bending sections on the surface of a metal workpiece. Hood is called stamping. This is an operation by which a three-dimensional product is obtained from such a flat metal surface, such as, for example, a stainless metal sheet. It is with the help of a hood that it turns into a cylinder, cone, hemisphere or takes on a box-shaped configuration. Sheet metal products should have a rim along the edge and around the holes, if they are made inside the workpiece. For example, flanging must complete the end of the pipe in order to install a flange on it. Such an operation requires a special tool.
By crimping, the opposite effect occurs. Flanging extends the ends of sheet metal workpieces, and crimping narrows. The same ends of the pipes or the edge of the cavity require an operation that is carried out externally through the conical matrix. Molding also refers to the basic operations related to stamping. It helps to change the shape of the individual elements of the stamped part, and the outer contour leaves unchanged. Volumetric stamping requires the use of special equipment and complex preliminary drawings, which is why it is almost never sold at home.
Press selection
For the processing of metals, even the mildest ones (for example, for stamping aluminum), special equipment is required: a hydraulic or crank press or guillotine shears. And of course, many knowledge is needed. For example, how to make calculations for the consumption of material and perform technical drawings. GOST requirements are always taken into account.
To choose the right press for stamping, you first need to clearly imagine the task that he has to solve. Performing operations such as punching or punching requires the use of stamping equipment with a simple action, with a small stroke of the slide and washers during processing. But already for the hood you need a completely different, more powerful equipment, where the slider and washers make a much wider stroke. Double-acting equipment has this ability.
GOST equipment
Punching, depending on the conditions of the task, can be done on the following types of equipment: one-, two- and four-crank. The latter - with the installation of large sliders. However, equipping the stamping press with a matrix does not depend on the design. The main work through movement is performed by a slider connected by its lower part to a movable die. And so that the slider of the press moves, the drive motor is equipped with elements of a kinematic chain: V-belt drive, a starting clutch, washers, a crank shaft, a connecting rod that regulates the stroke of the slider.
The slider is started with the help of a foot press pedal, which is connected with the starting clutch, after which its reciprocating movements directed to the press working table begin. The four-rod press has a different operating principle. His working bodies direct all the effort into the middle of the quadrangle, which is formed by four connecting rods. Such a device is successfully used for the manufacture of products of the most complex configuration: asymmetric or dimensional.
For complex products
To obtain high-quality products of complex configuration, a pneumatic press with two or three sliders is very widely used. The double-action press works with two sliders at the same time: the external fixes the workpiece, and the internal one draws the surface of the metal sheet. Thin sheets of metal are stamped with special friction presses, and thick sheets are stamped with hydraulic ones, which have more reliable washers.
A separate category of stamping equipment is explosion-controlled stamping. Such devices direct the power of the explosion to individual sections of the metal billet (usually of significant thickness). This is an innovative equipment, the work of which even on video looks very impressive. Bends and the general configuration of a complex product are processed using built-in vibrating scissors.
Stamping
Sheet stamping (for example, the manufacture of perforated sheet) implies the process of punching sheet metal. The rest of the stamping is volumetric. The used equipment for stamping equipment is divided into types. It can be instrumental, pulsed (explosion, magnetic or hydroimpulse), roll or stamping with elastic media. Sheet stamping can produce spatial and flat parts of various weights - from fractions of a gram, and various sizes - from fractions of a millimeter (here you can see the second hand of a watch). Sheet stamping also produces parts of many tens of kilograms by weight and several meters in size (car linings, rockets and airplanes).
They mainly use low-carbon steel, as well as alloyed - with special ductility, brass, copper, aluminum and magnesium with alloys, titanium and much more. Sheet stamping is almost all industries: rocket, aircraft, tractor, auto, instrument making, electrical industry, and so on, you can list everything. Its advantages are great.
Volumetric stamping
Volumetric stamping can be done in both cold and hot ways. Hot - pressure treatment, where the forging is formed using a stamp. Billets are rolled rectangular, round, square profile, which is cut into measuring blanks (sometimes not cut, but stamped directly from the bar, then separating the forging directly by a stamping machine).
Volumetric stamping is used in mass production and mass production, which increases labor productivity and reduces metal waste. Product quality also meets high standards. Such stamping gives products that are exceptionally complex in shape, which cannot even be obtained by free forging.
Stamps open and closed
Open dies allow you to observe the gap between the stationary and moving parts of the machine. During hot stamping, an outflow follows into the gap - metal, which closes the exit from the cavity and forces the rest of the mass to fill the cavity completely. In the process of deformation, excess metal enters the casing. But removing the flash is difficult.
Closed stamps do not allow you to look inside and observe the process - the cavity is closed. Oblio is also not provided. The device of such a stamp depends on the type of machine. Here it is necessary to strictly observe the accuracy of volumes and their equality in the workpieces and forgings: a lack of metal will leave the corners of the cavity empty, and an excess of it will make the forging larger than the required height.