The market for metal structures places ever-higher demands on the accuracy of parts mating. Working with metal pipes requires an operation with a high quality cut. When choosing a technology, it is necessary to take into account the properties of the material, such as strength, heat resistance, electrical conductivity, and others.
The subject of consideration will be cutting pipes with plasma. This is the most efficient technology with high productivity and processing accuracy.
3D plasma cutting of pipes and its types
By definition, this is the process of cutting a product into parts using a high-temperature plasma instead of a mechanical, flame or laser cutter. There is also milling, when a part of the material is cut out of the surface while maintaining the integrity of the part. Depending on the environment in which it occurs, the process is divided as follows:
- Simple. Compressed air or nitrogen is used as a carrier;
- With the use of inert gas. Increases the quality of cutting, as the process takes place in a clean environment;
- Water cooled. Protects equipment from overheating, absorbs harmful fumes.
According to the method of implementation, cutting is distinguished by an arc, when the material is a component of an electrical circuit, and a jet, when an arc is formed inside the cutter.
How does plasma cutting of pipes work?
Plasma is an ionized gas that conducts electricity. A pressurized gas stream is passed through a nozzle where the particles are accelerated to the speed of sound. An electric arc is created between the nozzle and the pipe surface. Under the action of an electroplasma arc heated to 20,000 degrees, the metal quickly melts. The liquid melt is removed from the surface by a high-velocity gas flow.
This method is called direct and is used for materials with sufficient conductivity. The cutting technique is called plasma-arc. This method has high performance at relatively low cost.
For metal pipes with low electrical conductivity, an indirect method, or plasma jet cutting, is used. In this case, as mentioned, the arc is formed in the torch itself and only the flow of hot ionized gas acts on the material. The method requires increased costs and is less productive.
Plasma cutting has a number of advantages:
- high productivity (with a thickness of up to 50 mm);
- local heating, respectively, the absence of thermal deformations;
- high-quality cut with high speed;
- the possibility of cutting along complex lines;
- The edges do not need to be sanded.
The disadvantages include:
- loud noise during operation;
- the appearance of cracks during the bending of the melted section.
Important! The use of 3D modeling allows you to create three-dimensional spatial images of objects with high accuracy. With the help of equipment with special control programs, the image is embodied in metal.
3D plasma profile cutting of pipes makes it possible to cut and process along complex contours on metal pipes of any section and profile, ensures high accuracy of the subsequent pairing of parts without additional processing.
What is plasma cutting equipment made of?
The complex consists of a hardware unit, a power source, a mechanized plasma torch. The plasma cutter is a body, inside of which there is a nozzle with a mechanism for swirling the plasma-forming carrier, as well as an electrode and a water-cooling jacket. It is connected to the gas line, in the absence of such a cylinder with compressed gas.
There are devices with and without a rotating arc, liquid-cooled or air-cooled. Water cooling allows the use of higher temperature plasma due to the high degree of gas compression.
Nozzles, electrodes are consumables, the timely replacement of which is mandatory.
There are high-frequency electrodeless devices based on inductive coupling with a power source, as well as microwave plasma torches.
The distance between the nozzle and the surface should be between 10 and 15 mm. If air is used as a carrier, it must be cleaned and dried.
When mechanizing the process, the device is placed on a stationary installation of a portal, portal-console or portal-pantographic type. Numerical control, magnetic copying, linear speed adjustment are used as moving systems.
The commonly used pipe cutting machines are described below.
Machine tool with numerical control
The machines allow for high-precision plasma cutting of pipes with minimal waste due to the presence of CNC. The machine itself is controlled by a controller or a separate computer. The control program is created on the basis of a three-dimensional model of the cut shape. If there is a sample, it can be scanned with a special scanner, which will allow you to generate a 3D image in electronic form.
Important! By varying the diameter of the plasma torches, the speed of passage and the angle of inclination, it is possible to obtain a high-quality cut of any complexity.
The main components that the CNC pipe cutter is equipped with:
- plasma torch;
- cutting table;
- support for moving the cutter;
- units for supplying gas, electricity and water.
Thanks to the development of software, robotic cutting is increasingly being used. Robots are widely used in automotive, mechanical engineering and other fields. It used to take weeks or even months to reconfigure equipment. It’s taking minutes now. Therefore, the scope of robots has expanded from mass production of the same type of parts to the implementation of individual orders.
In addition, automated systems provide continuous monitoring of the specified process parameters, which dramatically reduces the reject rate.
Today’s robots allow cuts at any angle, anywhere, with a robotic arm that can precisely move in any direction. The long arm allows you to cut large diameter pipes.
As additional equipment, robotic complexes can be equipped with sensor systems, technical vision systems that allow continuous monitoring of the process.
Thanks to the vision system, it is almost impossible to “not notice” a defective product. And also it becomes possible to identify deviations, then adjust the parameters during the technological cycle.
Thanks to these factors, robotic cutting is carried out at a level inaccessible to manual labor. The high cost limits its use.
Universal cutting system ESR
This is the next stage in the development of plasma pipe cutting technology. The system expands the capabilities of conventional machines. Drilling, punching, threading, other work can be done on one machine thanks to the possibility of a figured cut. This significantly reduces costs, time, money, production space.
The components of the system are:
- rotator with program control;
- mobile elements holding the pipe in a horizontal position;
- ventilation systems.
The pipe to be cut is mounted on trolleys, each of which is selected taking into account the length and weight of the product. Above it is a movable caliper with a burner, fixed on a portal that provides free movement of the caliper.
During processing, the pipe rotates around the longitudinal axis. Horizontal movements are synchronized with rotation, which allows you to accurately position the plasma cutter.
The installed 3D CNC head sets the desired angle of inclination and rotation of the plasma torch, which allows you to chamfer any complexity in one pass. This significantly saves time and money. The software has a database that stores the nesting library and provides for the rapid creation of new ones.
Pipe plasma cutting machine «Koral»
In the construction of gas pipelines, in other areas of technology, precise articulation of large diameter pipes, sometimes several in one place, is required. In case of misalignment, the thickness of the weld increases, which leads to a decrease in the strength and durability of the structure. The traditional method of marking pipes using paper templates is laborious and leads to large errors in the accuracy of the parts to be joined.
The Koral machine developed by Eckert uses the ESR system and is a CNC plasma pipe cutter. It is equipped with a 3D head with modern software, which allows for accurate cutting, ensuring that the dimensions of the product correspond to the given ones.
The control system is relatively simple, does not require long-term complex staff training. The use of a plasma arc allows you to make curly cuts, the quality of which excludes the subsequent processing of the flange. They produce modifications «Koral» 300, «Koral» 600, «Koral» 900. The number means the maximum diameter of the processed pipe.
The machine for high-precision plasma cutting of pipes is fully automated, provides continuous control of the arc height, combustion temperature, gas pressure, over all technological process parameters.
Important! The use of the machine allows you to significantly reduce the processing time of the flange compared to traditional methods.
Metal processing technologies have made a qualitative leap and continue to develop rapidly. New methods are emerging and existing ones are being improved.
Plasma technology occupies a leading position among all methods of metal processing due to the perfection of the process, high productivity, reasonable combination of price and quality.