Due to the precision and ease of processing, rolling of metal and cylindrical shells has been used for several hundred years and always remains relevant. Modern devices for rolling cones and composite are used both on an industrial scale and in the household. Depending on the type of machine, processing can be done independently if you study everything about rolling and types of equipment.
What it is?
Rolling, rolling is a technological operation or process of deformation of various sheet metal. For example, tin, copper, steel, and a number of polymer composite materials. In the course of rolling, by passing through special rotating rollers, the sheet material is evenly bent and takes on a certain shape. The output is cylindrical, conical and other shaped products, depending on the type and settings of the equipment.
When rolling, in most cases, cold stamping is used, parallel heating of the workpiece is carried out, as a rule, only for large volumes or processing thick sheets of material.
Less commonly, the term "rolling" is used in relation to the technological processing of metal pipes, when deformation of the extreme section of the product cut is performed to increase or decrease the diameter. After processing, pipes that are initially identical in diameter are connected to each other - they are tightly inserted into one another. For example, when the pipe is deformed along the radius for its strong and hermetic fixing in the seat of the tube sheet of the heat exchanger. The calculation of such processing is carried out according to the formula: D '= D o + Δ + K × S, in which:
- D '- indicators of the inner diameter of the workpiece after processing;
- D about - the inner diameter of the extreme cut before rolling;
- Δ is the diametrical gap between the pipe and the tube sheet;
- S is the wall thickness of the workpiece;
- K is the coefficient of the type of heat exchanger, the indicator ranges from 0.1 to 0.2.
The complexity of this type of rolling is determined by two main technical characteristics.
- Range - the difference between the initial internal diameter of the workpiece and the dimensions to which it can be radially increased, that is, deformed.
- Depth - the length of a separate section of the workpiece to which deformation is permissible.
For full-fledged rolling of sheet material, in accordance with the requirements of GOST, special equipment is needed - rolling machines. The type of processing, the type of finished product, the speed of rolling, as well as the accuracy and other design parameters of the products will depend on the power and technical capabilities of the equipment.
Rolling has an important advantage over other similar methods - the cold deformation process does not affect the properties of the metal, the material retains its original characteristics, and the integrity of its structural joints is not disturbed. This is especially important when machining various dissimilar metal alloys.
Where is it applied?
This type of metal deformation is used for the processing and production of various products. For example, when preparing finished products for stamping or as primary processing. Not only sheet metal or alloys are subject to rolling, but also pipes, rods, profiles, polymer materials from rubber compounds, plastic or plastics. After rolling or cold stamping, the structure of the material becomes denser, and its technical characteristics are significantly improved. Depending on the type and settings of the machine, during processing, products are obtained in the form of:
Rolling equipment is used today to produce a wide range of products for various fields and fields of activity:
- cylindrical shells;
- composite panels;
- wide band saws;
- channel for air conditioners;
- profiled metal corners;
- decorative building elements.
Rolling is necessary not only for the manufacture of new products, but also for various preliminary, additional and subsequent types of metal and composite processing - compaction, squeezing or flattening of workpieces. On the rolling equipment, the surface of the workpieces acquires a uniform gloss, irregularities, roughness are removed, the material becomes the same thickness over the entire plane. Considering that the blanks can have various shapes and configurations, to create the required design, the sheet is fed in one of three directions.
- Transverse - when rolling long elements of open tubular products.
- Longitudinal - for processing short elements and blanks of open pipes.
- Screw - for the production of products that do not involve subsequent joint welding.
Thanks to the development of modern technologies, the rolling technique is used both at enterprises and at home using miniature compact hand-held machines and special tools. In this case, the equipment can be made independently with your own hands. In the production workshops, professional large-sized equipment with an electric or hydraulic drive is used for rolling materials.
Such universal machines allow high-quality processing of large sheet materials - up to 12 meters long and up to 10 millimeters thick.
Rolling is used to process many types of materials, different in shape and structure. Therefore, the profile equipment can differ significantly in the type of design, purpose and technical capabilities. Modern bending machines for both professional industrial and home use are classified into four main types, depending on the power drive device.
Manual machines are mainly used only in households for domestic purposes, in one-off production or processing of materials. Such units are easy to operate, no special knowledge is required to work with them, and most importantly, they are autonomous and do not need additional power. Due to its compact size, high reliability and durability, the equipment is very popular among DIYers and in small workshops at enterprises.
An essential pole of manual rolling machines is low cost with high processing quality. You can assemble the installation with your own hands and light the costs to a minimum. The main disadvantage of manual equipment is that it does not allow processing materials with a thickness of more than 2 mm . An important disadvantage is the need to apply significant physical force - the position of the movable working shaft is manually adjusted, the rolling process, that is, the material is fed, is also carried out in manual mode.
In electrical devices, the material is fed due to a power electric motor, the capabilities of the equipment will also depend on its power - the speed of operation, the types of materials to be processed, the dimensions of the rolling equipment itself. Electric bending machines make the job easier, but the need for a network connection reduces their mobility. As a rule, such equipment is installed permanently in spacious workshops, large production facilities of enterprises. Electric machines allow processing sheet material with a thickness of 4-6 mm.
Among the disadvantages, significant costs for electricity are also noted - in order to reduce production costs, you can use low-power equipment up to 20 kW. A machine of low power will not cope with the task so quickly, but it will save on electricity and reduce the cost of products. High power electric bending machines are usually used only in large industrial enterprises focused on mass production or processing of large-sized workpieces.
The hydraulically driven bending machine is the most powerful of its kind, processing materials up to 10 mm thick. Hydraulic machines belong to the heavy class, they are several times superior in power and capabilities to manual and electromechanical installations. Apparatus with a hydraulic drive are used mainly in large industrial enterprises - power, machine-building or shipbuilding plants.
Almost all modern hydraulic machines are equipped with computer programmed control - CNC. Compared to other types, the units also have a more complex design, in which a large number of working elements are involved.
In addition, equipment with a hydraulic drive also has large dimensions, the machines are installed only permanently in spacious rooms. But on the other hand, they allow you to quickly and efficiently roll large volumes of products, while maintaining high processing accuracy.
Tools and fixtures
The main working unit of any rolling equipment is a cast bed made of durable metal alloys or cast iron. On the bed, the dimensions of which depend on the type of equipment, a special deforming device is mounted, consisting of several longitudinal rolls. Two work rolls are fixed tightly (they are stationary), and the third or fourth element provides rotation of the workpiece during operation. On some machines, the movable rolls can also be moved vertically, allowing the production of a wider range of products, processing of more types of materials.
The upper roll is mounted on the bed in such a way that, if necessary, it can be quickly removed or reconfigured for the production of products with different sections. Its adjustment is carried out with a special tool - a single screw or a ratchet-type mechanism, and in automatic rolling machines this action is performed programmatically. Adjustment means changing the technological characteristics of the equipment - increasing or decreasing the gap between the rolls. The use of special rolls with working grooves on the surface allows you to process and bend not only sheet material, but also metal rods or wires.
Manual machines are usually equipped with three rolls, since more elements will complicate the processing process. If you install a fourth roll, then physical strength will no longer be enough to bend a number of materials. The number of rolls on an electromechanical rolling machine is from 3 to 4, it all depends on their size and engine power. All professional hydraulic power units are equipped with four working shafts.
No additional tools are required to operate the rolling equipment, only some machines may require a certain size wrench to adjust the rolls.
Features of technology
Regardless of the type of rolling equipment, the rounding of the material or the workpiece takes place due to the third movable work roll. The shape of the future product will depend on its position and the gap between it and the two leading elements, its radius - the greater the distance between the rolls, the greater the radius of the workpiece. If the rolls are installed on the machine parallel to each other, then the workpieces become cylindrical.
When placing the third shaft at a certain angle, the shape of the products will be tapered . The fourth roll provides preliminary bending of the sheet material; on most modern machines it is equipped with an additional pneumatic drive. If necessary, the machines are equipped with rollers with a polished, rubberized or extra hard surface.
For information on what types of rolling are, see the next video.