Overcome the difficulties of laser cutting machine cutting metal pipe technology

Overcome the difficulties of laser cutting machine cutting metal pipe technology 

Accompanied by the rapid growth of the stainless steel pipe production and consumption, laser cutting tube equipment are growing rapidly in popularity, the demand of personnel and technology of laser cutting machine grown quickly.This highlights the shortage and lag in the laser cutting equipment and laser cutting Overcome the difficulties of laser cutting machine cutting metal pipe technology 

Accompanied by the rapid growth of the stainless steel pipe production and consumption, laser cutting tube equipment are growing rapidly in popularity, the demand of personnel and technology of laser cutting machine grown quickly.This highlights the shortage and lag in the laser cutting equipment and laser pipe cutting talent and technology, which is also reflected in some stainless steel enterprises, with advanced laser cutting equipment, but still exposed pipe cutting efficiency is low, poor quality management, resulting in the phenomenon of serious waste of pipe. 

Laser pipe cutting processing technology is a high production efficiency, productivity and strong technology.Can modified the design at the last minute without affecting the entire the production process.Greater benefits is that the end user can control the short version or medium version in production without making a large number of templates, so you can give more quickly respond to customer needs, so this does not need to make the molds.From the perspective of flexibility, laser cutting processing technology can be used to process any shape of the processing program, and the laser can be completed in any direction. The shape of the template can be changed quickly, without the help of any tool, providing the possibility to process a competitive personalized packaging or trademark. Accuracy is one of the advantages of digital systems. Laser processing can offset printing and finishing process in the presence of inaccurate, such as material may produce flexible deformation, the laser can be based on these deformation is adjusted, and the traditional template making is not. Laser tube cutting products processing is a very accurate and high level technology, Of course, this requires a certain cost of investment in the early stage, the following will focus on the relevant issues related to laser cutting and provide targeted solutions.  
Worker can draw,nesting,cutting with the professional pipe cutting and nesting software,generate cutting program,then full automatic laser cutting for the large length of stainless steel pipe.The speciality of tube nesting software is the basis and prerequisite for the realization of high volume, high efficiency and high quality cutting production of laser tube cutting machine. 
At present, the laser pipe cutting process, there are some quality problems, for example: led to cut some parts over burning, pipe cutting inclined plane for burning, part corner, and cutting circular parts circle deformation or cannot be closed, pipe directly lead to serious waste and cut tube production efficiency is low. CNC pipe cutting technology refers to the NC system of the cutting control software to provide advanced cutting tube technology and rich pipe cutting experience, pipe cutting workers to operate by skilled in the use of control system, to achieve high quality, high efficiency of CNC cutting. CNC laser cutting technology is a high volume, high efficiency, high quality cutting production methods, CNC cutting pipe is the core of CNC cutting system. 
Pipe cutting process due to pipe cutting (especially for tubular diameter of square tubes), slag, attached on the tube wall, most of the heat produced in the cutting is absorption of the workpiece, cutting density is large, often cause overheating pipes, corner and square tube four horns, burning, seriously affecting the ring incision quality, can't even cutting. For such problems, the following solutions can be used: 
1, increase oxygen pressure.           
2, improve the angular speed of synthesis by software.           
3, laser cutting headband height sensing with dynamic system can guarantee in the process of cutting, cutting the nozzle and the workpiece plane height remained unchanged (focus unchanged), cutting effect does not change with the surface of the workpiece affected. 
The proposed solution will improve the laser tube cutting processing equipment efficiency in the use of, so as to improve the cutting efficiency is low, poor quality management, pipe caused serious waste, improve production and processing enterprises product efficiency, for the enterprise to create a better profit. talent and technology, which is also reflected in some stainless steel enterprises, with advanced laser cutting equipment, but still exposed pipe cutting efficiency is low, poor quality management, resulting in the phenomenon of serious waste of pipe. 
Laser pipe cutting processing technology is a high production efficiency, productivity and strong technology.Can modified the design at the last minute without affecting the entire the production process.Greater benefits is that the end user can control the short version or medium version in production without making a large number of templates, so you can give more quickly respond to customer needs, so this does not need to make the molds.From the perspective of flexibility, laser cutting processing technology can be used to process any shape of the processing program, and the laser can be completed in any direction. The shape of the template can be changed quickly, without the help of any tool, providing the possibility to process a competitive personalized packaging or trademark. Accuracy is one of the advantages of digital systems. Laser processing can offset printing and finishing process in the presence of inaccurate, such as material may produce flexible deformation, the laser can be based on these deformation is adjusted, and the traditional template making is not. Laser tube cutting products processing is a very accurate and high level technology, Of course, this requires a certain cost of investment in the early stage, the following will focus on the relevant issues related to laser cutting and provide targeted solutions.  
Worker can draw,nesting,cutting with the professional pipe cutting and nesting software,generate cutting program,then full automatic laser cutting for the large length of stainless steel pipe.The speciality of tube nesting software is the basis and prerequisite for the realization of high volume, high efficiency and high quality cutting production of laser tube cutting machine. 
At present, the laser pipe cutting process, there are some quality problems, for example: led to cut some parts over burning, pipe cutting inclined plane for burning, part corner, and cutting circular parts circle deformation or cannot be closed, pipe directly lead to serious waste and cut tube production efficiency is low. CNC pipe cutting technology refers to the NC system of the cutting control software to provide advanced cutting tube technology and rich pipe cutting experience, pipe cutting workers to operate by skilled in the use of control system, to achieve high quality, high efficiency of CNC cutting. CNC laser cutting technology is a high volume, high efficiency, high quality cutting production methods, CNC cutting pipe is the core of CNC cutting system. 
Pipe cutting process due to pipe cutting (especially for tubular diameter of square tubes), slag, attached on the tube wall, most of the heat produced in the cutting is absorption of the workpiece, cutting density is large, often cause overheating pipes, corner and square tube four horns, burning, seriously affecting the ring incision quality, can't even cutting. For such problems, the following solutions can be used: 
1, increase oxygen pressure.           
2, improve the angular speed of synthesis by software.           
3, laser cutting headband height sensing with dynamic system can guarantee in the process of cutting, cutting the nozzle and the workpiece plane height remained unchanged (focus unchanged), cutting effect does not change with the surface of the workpiece affected. 
The proposed solution will improve the laser tube cutting processing equipment efficiency in the use of, so as to improve the cutting efficiency is low, poor quality management, pipe caused serious waste, improve production and processing enterprises product efficiency, for the enterprise to create a better profit.

Laser cutting machine cutting 7 types different metal materials

Laser cutting machine cutting 7 types different metal materials

Metal on the initiation of 10.6 um laser beam absorption rate is only from 0.5% ~ 10%, however, when with a power density of more than 106w/cm2 focused laser beam irradiation to the metal surface, but it can in the microsecond time soon so that the surface begins to melt. The absorption rate of most metals in the molten state has risen sharply, which is generally improved by 60%~80%.

1.Titanium and its alloys.          

Pure titanium can be very good coupling focused laser beam transformation of heat energy, auxiliary gas oxygen chemical reaction, cutting speed, but easy to generate oxide layer on the cut edge, not careful will cause too much. For the sake of safety, the use of air as an auxiliary gas is better, to ensure the quality of cutting.          
Aircraft manufacturing industry commonly used titanium alloy laser cutting quality is better, although there will be a little sticky residue at the bottom, but it is easy to clean up.

2.Nickel alloy.          

Nickel based alloy, also known as super alloy, a lot of variety. Most of them can be carried out to melt and cut.

3.Carbon steel.          

Modern laser cutting machine can cut carbon steel plate with the maximum thickness of up to 20MM, the use of oxidation and melting cutting mechanism to cut carbon steel cutting seam can be controlled in a wide range of satisfaction, the thin sheet of its cut can be narrow to about 0.1MM.

4.Stainless steel.          

Laser cutting is an effective tool for the manufacture of the stainless steel sheet as the main component. In the strict control of the laser cutting process of the heat input measures can be restricted to the edge of the heat affected zone is very small, so that it is very effective to maintain the good corrosion resistance of such materials.

5.Alloy steel.         

The majority of alloy structural steel and alloy tool steel using laser cutting method to obtain good cutting quality. Even some of the high strength materials, as long as the process parameters are properly controlled, can get straight, non stick slag cutting edge. However, for high speed tool steel and hot die steel, laser cutting machine will have the phenomenon of corrosion and slag.

6.Aluminium and alloys.          

Aluminum cutting is a melting laser cutting mechanism, which is mainly used to blow away the molten product from the cutting area. For some aluminum alloys, it should be noted that the prevention of micro cracks on the surface of the cutting seam is noticed.

7.Copper and alloys.         

Copper (copper) because the reflectivity is too high, basically can not use CO2 laser beam cutting. Brass (Red copper) using a higher laser power, auxiliary gas using air or oxygen, can be a thin sheet of cutting.

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Common problems and treatment methods in laser cutting

Common problems and treatment methods in laser cutting

1.Any kind of thermal cutting technology, in addition to a small number of cases can be from the edge of the board, the general must wear a small hole in the board. Before the laser punching compound machine with a hole punch out first, and then again from the hole at the beginning of laser cutting. Basic method for two kinds of perforation of laser cutting machine without punching device:

Blasting perforation
After the material is irradiated by a continuous laser, a concave hole is formed in the center, and the oxygen flow from the laser beam is quickly removed to form a hole. And sheet thickness is related to the size of the hole and blasting perforation average diameter is half of the plate thickness, so for thick plate blasting perforation diameter larger diameter, should not require higher in precision machining parts, can only be used for waste. In addition, due to the use of oxygen pressure and cutting the same, the splash is larger.

Pulse perforation
Pulsed laser with high peak value is used for melting or vaporization of a small amount of material, air or nitrogen is used as an auxiliary gas to reduce the expansion of the pores due to heat release and the gas pressure is less than the oxygen pressure during the cutting process.
Each pulse laser produced only a small particle injection, and gradually deepened, so thick plate perforation time takes a few seconds. Once the perforation is completed, the auxiliary gas is changed to oxygen for cutting. The perforation diameter is smaller and the perforation quality is better than that of the blasting hole. The laser used in this system should not only have high output power, but also more important is the time and spatial characteristics of the beam, so the general cross flow CO2 laser can not meet the requirements of laser cutting. In addition, a more reliable pneumatic control system is needed in order to realize the gas type, gas pressure switch and perforation time control.In the case of using pulse perforation, in order to obtain high quality cut, from the workpiece at rest, the pulse perforation to the workpiece constant velocity continuous cutting transition technology should be paid attention to. Theoretically, it is usually possible to change the cutting conditions of the accelerating section, such as the focal length, the position of the nozzle and the gas pressure, but in fact, the possibility of the above conditions is not very much due to the time is too short. In the process of industrial production, the method of changing the average power of laser is used to compare the reality, the specific method is to change the pulse width, change the pulse frequency, and change the pulse width and frequency.

2. cutting holes (diameter and thickness) analysis of deformation
This is because the machine (only for high power laser cutting machine) in machining holes not take the blasting perforation, but with pulse perforation (soft puncture), which makes the laser energy in a very small area is too concentrated, non machining area was burned, cause deformation of the hole, the processing quality is affected. Then we should be in the process, pulse perforation (soft puncture) to blasting perforation (ordinary puncture) way to solve. For small power laser cutting machine is just the opposite, in machining should adopt way pulse perforation to achieve better surface finish.

3.when the laser cutting of low carbon steel, the solution to the work of burr
According to the working principle and design of CO2 laser cutting, and analysis the following reason is caused by machining burrs in the main reason: the laser focus on the position is not correct, need to be adjusted according to the focus position test, offset focus; the laser output power is not enough, need to check the laser generator is normal or not, if the normal, is to observe the effect of laser numerical control output button is correct, adjust the line; the cutting speed is too slow, the need to increase the line speed in operation control; the purity of cutting gas is not enough, need to provide high quality gas cutting work; laser focal shift, need to be adjusted according to the focus position test, offset the focus of the machine running time is too long; the stability, the need to shutdown and restart.

4.Laser cutting of stainless steel and aluminum plated zinc plate, analysis of the causes of burr formation.
The factors above, first consider the low carbon steel cutting burr, but not simply accelerate cutting speed, because increased speed sometimes sheet cutting not to wear, this kind of situation in processing aluminized zinc plate is particularly prominent. At this time should be integrated into other factors to consider the machine to solve, such as whether the nozzle to replace, rail movement is not stable, etc..

5.Analysis of laser machine can not cut through
Analysis revealed that several of the following is instable processing of: laser head nozzle selection and processing board does not match the thickness; laser cutting line speed is too fast, need to operate the control lines are reduced speed; in addition, also need to pay special attention to, in the laser cutting machine cutting more than 5mm carbon steel needs to be replaced laser lens focal length of 7.5 ".

6.Method for solving non normal spark in cutting low carbon steel
This situation will affect the cutting section of the parts finish machining quality. At this time, in the case of other parameters are normal, should consider the following: laser head nozzle loss, should be promptly replace the nozzle. In the case of no new nozzle replacement, the cutting work gas pressure should be increased; the nozzle and the laser head are connected at the screw thread. At this point should be immediately suspended cutting, check the laser head connection status, re good thread.

7.Selection of puncture point in laser cutting
Laser cutting the working principle of the laser beam is: in the process, material after the irradiation of laser in the center of the formation a pit, and then by the work flow and laser beam coaxial soon will be molten material removal of the formation of a hole. This hole is similar to line cutting of the thread hole, laser beam on this hole for the processing of opening and starting point of contour cutting, usually under flight light path laser beam walk line direction and the parts to be machined vertically cutting contour tangent direction. Therefore, laser beam in began to penetrate the plate into the cutting contour parts of this period of time, the cutting speed in vector direction will have a great change, namely the direction vector of 90 degrees rotation by vertical to the cutting contour tangent direction turn and cutting contour tangent coincidence, and contour tangent angle is 0 degrees. In this way, the cutting surface of the processed material is relatively rough cut surface, which is mainly in the short time, the laser beam in the direction of the movement of the vector is very fast. Therefore, in the use of laser cutting parts, we should pay attention to this aspect of the situation. , in the design of components of surface cutting fracture no roughness can not to do manual processing in laser cutting programming, to control the software automatically generates the puncture point; however, when design of machining cutting section has higher roughness requirements, note to this problem, usually in series laser cutting program of laser beam starting position be manually adjusted, namely artificial for the puncture point of control. The need to produce the original laser puncture point program moved to the reasonable position of need, to reach the surface precision requirements of the processing parts.

How set the parameters of plasma cutting machine?

How set the parameters of plasma cutting machine?

1.Cutting electric current

The cutting electric current is the most importante parameter.It decide the cutting thickness and speed directly,also the cutting ability.
Influence
The cutting current increases, the arc energy increases, the cutting ability is improved, and the cutting speed is increased.
The cutting current increases, the arc diameter increases, the arc becomes thick and the cutting line becomes wide.
But if electric current is too big,the nozzle is easy to hurt.The hurt nozzle give bad influence to cutting result.So before cutting,we should set suitable electric current and nozzle according the metal thickness.

2.Cutting Speed

The best cutting speed needs test with certain machine and certain metal thickness.Because the different material,different thickness,diffrent melting point and thermal conductivity ,so the cutting speed is different.The main performance:
Increase the cutting speed appropriately can improve the result of cutting,the cutting line becomes narrow,the cutting surface becomes smooth and reduce the distortion.
If the cutting speed is too fast,the cutting line energy is lower than the required value, cut seam in the jet can't quickly melted cutting melt immediately blew and the formation of larger drag, accompanied by incision slag hanging, the surface quality of the incision down.
When the cutting speed is too low, because the cut is plasma arc anode, in order to maintain the stability of the arc's, anode spot or anode region must from recent arc cutting seam found near the conduction current place, at the same time will pass more heat to a radial jet, so make the incision became wide, on both sides of the notch of molten material in the bottom flange aggregation and coagulation, form is not easy to clean the slag hanging, and incision margin due to excessive heating and melting and the formation of fillet.
When the velocity is extremely low, as the incision is too wide, or even extinguished arc. Thus, good cutting quality and cutting speed are inseparable.

3.Arc voltage

We generally believe that the power supply is normal output voltage for cutting voltage.
Plasma arc cutting machine usually have high no-load voltage and working voltage, the use of high ionization energy in gas such as nitrogen, hydrogen or air, stability needed for the plasma arc voltage will be higher. When the current and voltage of the means of improvement of arc enthalpy and cutting ability. If the increase in the enthalpy, reduce the diameter of the jet and increase the gas flow, often can get faster cutting speed and cutting quality is better.

4.Work gas and gas flow

Working gas include cutting gas and auxiliary gas, some equipment also requires arcs gas, usually according to the types of cutting material, thickness and cutting method to choose proper working gas.Cutting gas need ensure the formation of plasma jet, but also need ensure the removal of molten metal oxides and incision.A large gas flow will take more heat from the arc, making jet length becomes shorter, resulted in cutting capacity is decreased and arc instability; too small gas flow the plasma arc lost due to the straightness and the cutting depth shallow, but also easy to produce hang slag; so the gas flow must with cutting current and speed very good cooperation.Now most plasma arc cutter control the gas flow according the gas pressure,because when the gun body aperture when the gas pressure control will control flow.When we choose different gas pressure of different thickness metal usually according the parameters from manufacture.If there are other special application, the gas pressure need to be determined by the actual cutting test. The most commonly used working gas: argon, nitrogen, oxygen, air, H35, ar - N2 etc..

Argon

Argon is hardly any reaction of metal at high temperature, argon plasma arc is stable. And the use of nozzle with electrodes have higher service life. But the argon plasma arc voltage is low, the enthalpy value is not high, cutting ability is limited, and cut the air than the thickness of the cut about 25% lower. In addition, in argon, protect the environment, the surface tension of molten metal is larger, about 30% higher than that in nitrogen environment, so there'll be more hang slag problem. Even using the mixture of argon and other gases will be cutting slag sticking tendency. Therefore, it is rarely used alone in pure argon plasma cutting.

Hydrogen
Hydrogen is often used as auxiliary gas and other gas mixed functions, such as the famous gas H35 (the volume fraction of hydrogen is 35%, the rest of the argon) is one of the strongest gas plasma arc cutting, the main enrichment in hydrogen. Because the hydrogen can significantly improve the arc voltage, the hydrogen plasma jet has high enthalpy, when mixed with argon plasma jet, the cutting ability is greatly improved. General of metal materials with the thickness of more than 70mm, commonly used as argon + hydrogen gas cutting. If the use of water jet to further compress argon + hydrogen plasma arc, also can obtain higher cutting efficiency.

Nitrogen

Nitrogen is a kind of common work gas, under the conditions of higher voltage and nitrogen plasma arc has better stability and higher than the argon gas jet power, even if is cutting liquid metal viscosity materials such as stainless steel and nickel base alloy, incision of inferior hanging slag quantity are few. Nitrogen can be used alone, also can use with other gas mixture, such as automatic cutting often use air or nitrogen as the working gas, the gas has become the standard high speed cutting carbon steel gas. Sometimes nitrogen is also used as an oxygen plasma arc cutting of arc gas.

Oxygen

The oxygen can improve the low carbon steel material cutting speed. Use oxygen cutting, cutting mode and flame cutting is difficult to imagine, plasma arc of high temperature and high energy of the cutting speed faster, but must with the use of high temperature oxidation resistance of electrode, and the electrode for arc anti impact protection, to prolong the electrode life.

Air containing volume fraction of about 78% of the nitrogen, so use air cut formed by the hanging slag and nitrogen for cutting very imagine; air also contains a volume fraction of about 21% oxygen, because the existence of oxygen, air cutting speed of low carbon steel material is also very high; at the same time the air is the most economical working gas. But the single use of air cutting, will hang slag and incision oxidation, nitrogen, and the electrode and the nozzle of the lower life will also affect the work efficiency and cutting costs. Five, the nozzle height: refers to the nozzle surface and the cutting surface distance, it constitutes a part of the whole arc length. Due to the power supply of plasma arc cutting generally use constant current or steep drop characteristic, nozzle height increased, the change in current is very small, but will the arc length increased and resulted in the increase of arc voltage, so that the arc power increase, but also to expose in the environment of arc length growth, increased energy loss in the arc column. In the two factors of the case, the former is completely offset by the latter, but will make the cut of the effective energy decreases, and the cutting capacity decreased. The performance is often a cut of the jet blow force is abate, incision of the lower residual slag increased, the upper edge of the melt and appear a round. In addition, considering the shape of plasma jet, jet diameter is expanded outward from the gun in, increase the height of nozzle will inevitably cause incision width increase. Therefore, selecting the nozzle height as small as possible to improve the cutting speed and cutting quality is beneficial, but may cause double arc phenomenon of the nozzle at low altitude. The ceramic nozzle can be set to zero nozzle height, or nozzle end direct contact surface is cut, you can get a good effect.

5.Cutting power density

In order to obtain high shrinkage of plasma arc cutting arc, cutting nozzles have adopted the smaller nozzle aperture, longer channel length and strengthen the cooling effect, which can increase the effective section of the nozzle in the current, arc power density increases. But at the same time compression also makes the arc power loss increase. Therefore, the actual used to cut energy efficient to smaller than the power output of the power and the loss rate generally between 25% - 50%, some methods such as water constricted plasma arc cutting energy loss rate will be greater, and in the cutting process parameter design or cutting the cost of economic accounting should consider this issue.

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