Stamping, for which a metal press is used, is one of the most common technological operations for processing this material. The essence of this procedure is to give a workpiece made of metal the necessary shape, for which plastic deformation is used, extruding a certain relief, patterns or punching holes. Presses for metal processing, depending on the list of tasks for which they are intended, differ from each other both in their technical parameters, as well as the design.

Types of stamping technological operations and equipment

Stamping as a method of processing metal blanks can be:

• hot;
• cold.

The first implies that the metal is processed in a heated state. The big advantage of hot stamping is that when it is performed, the characteristics of the workpiece are improved (in particular, the metal structure becomes denser and more uniform). Meanwhile, no scale layer is created on the surface of metal blanks processed using the technology, while the dimensions of finished products are more accurate, and their surface is smoother.

According to the type of workpiece subjected to stamping, such a technological operation can be sheet or volumetric. Stamping of the first type is used for processing sheet metal blanks; this technology is used to produce:

1. dishes;
2. jewelry;
3. weapon;
4. medical equipment and instruments;
5. parts of clocks, household, climatic equipment and electrical equipment;
6. parts for a complete set of automotive equipment;
7. details of machine tools and other engineering products.

Finished metal products obtained by technology do not need further development. The formation of their geometric parameters during forging occurs in special forms in which hot or cold metal is subjected to punching.

The press machine is usually used for:

• production of metal blanks by forging;
• pressing in and pressing out shafts, bearings and gears;
• performing stamping of sheet and volumetric type.

According to the principle of operation, pressing machines can be mechanical or hydraulic type, perform metal processing by static or impact methods.

Pressing equipment mechanical type according to its design, it can be:

• eccentric;
• crank.

Crank machines are used for both cold and hot. This stamping equipment is also used to perform such technological operations as drawing, punching and punching. The hydraulic press is used for stamping and forging technological operations with bulk metal blanks.

According to their functionality, pressing machines are divided into the following types:

• universal;
• special;
• specialized.

The universal pressing machine has the widest functionality, you can use such equipment to perform almost any forging operation. Specialized dies or presses are used to realize one technological process. The minimum functionality is possessed by special presses that are used for stamping products of the same type, while their work is based on one technology.

The design and principle of operation of the press equipment

The design of any equipment for stamping consists of the following elements:

1. drive motor;
2. movement transmission mechanism;
3. actuating mechanism.

Depending on how the drive motor of the press is connected to its actuator, machine tools with communication are distinguished:

1. mechanical;
2. non-mechanical, carried out by liquid, gas or steam.

As an actuator, which is equipped with equipment for stamping, can be traverses, slider, rolls, rollers and women.

Crank type presses

The main structural element of these presses is the crank mechanism, which converts the rotational movement received from the drive into the reciprocating movement of the slider. The actuator, which is equipped with a stamping press of this type, is connected directly to the slider, capable of developing a force of up to 100 tons. The movement of the slider in such presses is carried out with the same frequency.

Crank type presses can be single type, double or triple acting. Using such machines, you can perform the following technological operations:

• stamping using matrices of open and closed type;
• sheet metal cutting;
• firmware;
• the formation of the finished product by extrusion;
• combined processing.

In cases where more powerful equipment is required to form a finished product from a metal billet, hydraulic-type machines are used.

Hydraulic presses

Using a hydraulic press, it is possible to press both larger and thicker-walled metal parts. Such equipment for sheet stamping, forging, forging, bending and other technological operations, depending on the specific model, can develop forces from 150 to 2000 tons or even more.

The main structural elements that any is equipped with are two cylinders of different diameters that are filled with a working fluid and communicate with each other. In each of these hydraulic cylinders, a piston is installed that creates pressure of the working fluid or moves under its influence. It is the movement of the pistons in the hydraulic cylinders that ensures the movement of the actuator of the equipment. The amount of force that such a stamping press can create is determined by the difference in the diameters of its hydraulic cylinders.

Radial forging presses

A radial forging machine is a molding press in which preheated metal ingots are turned into finished products of a cylindrical configuration. The design of this type of press is:

• induction furnace, in which the workpiece is preheated;
• a conveyor for feeding the workpiece into the processing zone;
• gripping mechanisms, with the help of which the workpiece made of metal, constantly rotating, passes through the forging zone;
• worm gear connected to the electric motor and responsible for the operation of the gripping mechanisms;
• four shafts with eccentric axle boxes transmitting movement to a connecting rod with a striker, between which a slider is fixed (the shafts themselves receive rotation from the drive motor by means of a V-belt transmission);
• copy drums responsible for the synchronous approach of the strikers and the subsequent movement of the workpiece;
• spring clutch providing braking of the part at the moment of its processing by strikers.

The radial forging machine is used to obtain square or round forgings close to the profile of finished products.

The hydraulic punching press allows for the bending of thick-walled sheets, strips and bars. The range of work can be expanded by purchasing additional equipment. This will allow cutting down ventilation shutters, punching holes of various diameters, processing pipe edges and forming metal blanks with high accuracy.

Hydraulic punch presses help

• significantly increase the volume of production,
• perform rather complex metal work,
• don't stop manufacturing process during the transition from the production of one workpiece to another.

Sahinler hydraulic punch presses: description

1. In models HPM 65, 85, 115 and 175, the number indicates the force that is applied in the production of one part. The thickness of the punched material depends on the value of this indicator.
2. HPM 65, 85 and 115 DP have two independent working tables.
3. HPM 65, 85, 115, 175 CNC are optimally adapted for punching holes in precisely marked places on sheet metal in the X and Y coordinates.

The punching press is equipment for cold working of metals by pressure.

It is mainly used for punching various holes in sheet metal.

The principle of operation is based on the conversion of external energy into potential energy by transferring it to the actuator, while the metal is separated by pressure using a movable tool that shifts the material relative to the stationary tool. Such equipment is manual, which in turn is divided into lever-screw and hydraulic.

On the manual presses punch holes no more than 20 mm. in metal up to 20 mm thick. The main convenience is that, due to their small size, they are easy to move. There is drive (mechanical) equipment based on a crank (eccentric) shaft.

Mechanical punch presses are available in vertical and horizontal versions. They are used to speed up the process of punching holes in the details of structures that are manufactured in mass and serial production. They can have a large number of holes and punches in the matrix.

There is a division of punching presses according to the design into single-stamp, two-stub, four-stub and multi-stub. Not all mechanical presses are equal in terms of performance.

In a plate bending machine equipped with a multi-stamp tool, the punches work in steps and due to this, you can get more productivity than others.

For mass production, holes are punched on vertical copy presses with a duplicator table. The latter are designed for punching holes with any shape and arbitrary location.

Design

The design of the punching press consists of a vertical frame where a matrix for the punch is located on the lower working surface, and the punch itself is fixed above the matrix in a slider that receives movement from an eccentric and performs reciprocating movements in special guides.

There are punch presses with program management having its own design, a table moving in perpendicular directions and a turret, the mechanism of which is equipped with a drive that programmatically sets the tool to the cutting position.

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Hole punching. Punching presses.

Punch and matrix.

When punching holes, the role of the upper movable knife is performed by the punch (stamp), and the lower, fixed knife is performed by the matrix (stamp). The hole formation process and the working parts of the punching device are shown in fig. one.

The end of the punch, which is included in the matrix, and the hole in the matrix have the shape of a truncated cone, vertex facing up. The cutting edges of the punch and matrix have angles of 99°, bevel angle of 1°. With this shape of the punch, friction is reduced during its passage through the pierced metal. With the conical shape of the die hole, the extruded metal easily falls out of the die hole.

Fig.1. Metal penetration:

1 - punch; 2 - matrix.

Punches and dies are made from tool carbon steel and are made interchangeable, i.e., they are made according to certain normals.

To punch a hole, the sheet is laid so that the core a . delivered on the sheet during basting, fell exactly under the cone of the punch. Then the punch is turned on, which, by pressing on the sheet between cutting edge in dies and cutting edge b punch, shears metal.

Lever and screw bear.

Holes are pressed through on lever presses and bears manually. Two types of bears are used: lever and screw. The screw bear (Fig. 2, a) looks like a steel bracket; it can be forged or cast. At the lower end of the bracket there is a fixed matrix, and the screw with the punch passes through its upper end. The sheet is placed between the matrix and the punch so that the tip of the punch enters the recess marked by the core. Then turn the screw 1 handle 2 . The punch cuts into the metal and pierces a hole. The work requires a lot of effort, so the bears are used to pierce holes of small diameters and in sheets of small thickness.

Fig.2. Medvedka:

a - screw; 1 - screw; 2 - handle; 3 - bracket (case); 4 - sheet; 5 - punch; 6 - matrix;

b - lever; 1 - screw; 2 - lever; 3 - bracket (case).

More perfect is the lever bear (Fig. 2, b). Medvedka has a screw 1 with left and right cut. The lower nut of the screw is connected by a lever to the punch. As the screw rotates, the lever moves and the punch cuts into the metal, forming a hole.

Medvedki are inefficient and are not used for mass production. Usually bears are used when repair work for punching a small number of holes.

Manual punching press. Press manual lever.

Manual punching and lever presses also work on the principle of the bear. When punching holes in thin sheets, manual punching and lever presses can be compared in productivity and economy with powered presses.

Punching presses. Structures and principle of operation.

Driven punching presses for punching holes used in repair shops are welded, with welded iron or steel cast beds. Most often they are made double, because they are more compact and take up less space. A table made of steel sheets is installed in front of the punching presses, they serve as supports for the processed sheets. Tables for a punching consist of a goat with rollers. The rollers have slots for the vertical shelf of the corner. Punching presses are most often made with a belt drive from an electric motor and less often hydraulic.

In addition to punching presses, automatic punching presses are used in repair shops to punch holes.

For punching holes, each sheet is pre-marked or outlined. On automatic punching presses, the division of the sheet into the required number of equal parts occurs automatically. In this case, the straightened sheet is attached to a table that moves along the machine. The machine table can be stopped at any place by an automatic switch, which is driven by an electric drive.

To obtain the required number of divisions, only four corner points (on which cores are placed) and center lines are applied to the sheet. The sheet is first set with one corner punch against the pointer associated with the dividing device, and is moved by the machine support to another corner point on the same center line, automatically determining the distance between them. The support then returns to starting position, the divider is set to a certain number of divisions according to the number of required holes, and the machine pierces the holes.

The rest of the holes on the sheet are also pierced.

Large holes (for manholes, branch pipes, etc.) in the middle of the sheet are formed by puncturing. To reduce the subsequent processing of the edge of the hole, the punch is given rectangular section with rounded corners.

The edges of the hole, machined with such a punch, have the correct shape without protrusions, do not require hemming with a chisel, but are only filed.

Fig.3. Device for cutting holes for flame tubes.

Recently, large holes are formed by gas cutting. Pipe holes, the walls of which must have a smooth surface, are drilled using a special tool (Fig. 3.).