With the continuous development of heavy industry, laser cutting technology has developed from thin plate cutting to large-scale cutting of thick plate, and laser cutting has gradually entered the era of high power. Industrial manufacturing in the new era puts forward new requirements for the cutting accuracy, speed and thickness of metal sheets. The power of laser cutting machines is getting higher and higher. From the perspective of industrial development, high-power laser cutting machine is the inevitable product of a certain stage, and also the general trend of industrial development.

01

preface

In the field of metal sheet processing, the advantages of laser cutting machine are very prominent. Because of its advantages such as high accuracy, fast speed and good quality, it has gradually replaced the traditional processing technology and become the core equipment for metal sheet cutting [1]. From the rise of laser cutting machines, to the replacement of YAG, CO2 and other machines by fiber laser cutting machines, to the continuous introduction of high-power laser cutting machines, high-power equipment has become the general trend for cutting thick plates and cutting efficiency.

In recent years, high-power laser cutting machines have become a hot topic in the field of laser cutting, and many enterprises have continuously launched fiber laser cutting equipment of more than 10000 watts. For the sheet metal processing industry, the birth of high-power cutting equipment has greatly improved the thickness and efficiency of sheet metal cutting. The appearance of this high-power cutting machine constantly breaks the limit of material cutting thickness. The resulting reduction in the price of thick plate processing forms a good cycle and promotes the further expansion of the application field of laser cutting.

02

Introduction of high power laser cutting machine

(1) Introduction to high power cutting machine

Laser cutting machine can be divided into low power, medium power and high power according to power. For stainless steel and carbon steel with general thickness, low-power laser cutting machine can cut well. For cutting thick plates and cutting efficiency, high-power laser cutting machines can be well realized. Therefore, laser cutting machines with laser power of more than 10000 watts are collectively referred to as high-power laser cutting machines (see Fig. 1).

(2) Specifications of fiber laser power

According to the different thickness of metal plate cut by laser, the optical fiber excitation selected on the high-power cutting machine

The power specifications of lighters are also different. From the current development trend, in the metal processing market, large, medium and small enterprises have gradually upgraded to a variety of specifications, as shown in Table 1.

(3) Specification of gas used

When the high-power laser cutting machine is working, in order to ensure the cutting accuracy, cutting speed, cutting section effect and many other advantages, the purity of oxygen used is required to be high, generally 99.99%.

03

Characteristics of high power laser cutting machine

3.1 technical breakthrough

(1) High speed cutting machine with high dynamic performance

The machine tool equipped with the ten thousand watt fiber laser adopts the new triangular structure beam, which has the following characteristics: ① the weight is reduced by 30%, and the dynamic performance is significantly improved. ② The maximum moving speed can reach 200m / min and the acceleration is 4G. ③ The weight of the base is increased by about 20%, and the fixing mode of the machine tool is changed to eliminate the impact of high acceleration movement on the machine tool.

(2) Brand new software system

The software and control system are like the brain and command center of the machine tool. In addition to the bonus brought by the hardware upgrade, the difference in the performance of the machine tool mainly comes from the difference in the software and control system, and often varies greatly.

(3) Stable cutting speed up to 100M / min

① The response speed of the capacitive sensor is 3 times higher than that of the traditional cutting head. ② The z-axis speed is increased, the operation is non-stop and more smooth, the sheet cutting efficiency is increased by more than 30%, the frog jump function is improved, and the acceleration adaptation function is improved. ③ Improve the functions of rapid piercing and precision piercing as well as remote diagnosis, and reserve intelligent interfaces for realizing the functions of "industry 4.0" [2].

3.2 characteristics of cutting head

The high-power cutting head is the core component to ensure cutting stability in the case of high-power continuous operation. It has the following characteristics: ① the high-power cutting head has a cooling system with better sealing and more sufficient cooling, a focus with a wider application range and a high-temperature resistant lens. ② Due to the influence of the high-power thermal lens effect, the cutting head will have focus drift when it works for a long time. In order to overcome the focus drift, the high-power cutting head adopts a new gas path design structure and replaces the nozzle with a new structure, so as to improve the cutting speed and cutting stability.

3.3 high power laser cutting ability

(1) The thickness of the cutting thick plate keeps increasing

At present, the thickness of aluminum alloy plate and stainless steel plate cut by high-power laser cutting machine can reach 40mm and 130mm respectively. With the continuous upgrading of high-power laser cutting machine technology, the thickness of cutting materials will continue to increase, the price of thick plate processing will gradually decrease, and the application of high-power laser cutting machine in the field of thick plate will be accelerated [3].

(2) Efficiency multiplication of thin plate in cutting

① When cutting a stainless steel plate with a thickness of 3-10mm, the cutting speed of a 10000 w laser cutter is more than twice that of 6000 W. ② In the cutting application of carbon steel, the 10 000W laser cutting machine can achieve fast bright surface cutting of 18 ~ 20mm / s, which is twice the normal standard cutting speed. ③ Compressed air or nitrogen can be used to cut carbon steel plates within 12mm, and the cutting efficiency is 6-7 times that of oxygen cutting carbon steel.

3.4 bed characteristics

(1) The equipment is equipped with super load-bearing mechanical structure

All high-power cutting machines are equipped with cast-iron beds. Flake graphite cast iron with a minimum tensile strength of 200MPa is used for integral casting. The carbon content, compressive strength, vibration damping and wear resistance have been greatly improved (see Fig. 3).

(2) Characteristics of cast iron bed

① The bed has good lubrication performance, corrosion resistance and dimensional stability, reducing the machining error caused by the vibration of the bed. ② Reduce the loss of the equipment in use, improve the stability coefficient by more than 30%, improve the quality accuracy by more than 30%, and improve the service life of the bed by more than 70 years.

3.5 automatic nozzle replacement

(1) Manual nozzle change mode

During cutting, the nozzle needs to be replaced according to the thickness and material of the cutting material. For many years, the nozzle has been replaced manually, which is not only inefficient, requires repeated labor of technicians, but also difficult to ensure the accuracy and stability after replacement. How to replace the nozzle efficiently and quickly, and ensure that every replacement is foolproof and maintains accuracy, is a technical problem in the field of laser cutting.

(2) Automatic nozzle replacement technology

The high-power laser cutting machine applies the function of automatic nozzle replacement. It can realize automatic nozzle replacement, laser head calibration, automatic nozzle cleaning and other functions, reducing the amount of manual repetitive labor. Automatic nozzle replacement can be realized by operating corresponding commands on the touch screen. The automatic nozzle replacement technology has the following advantages:

1) It reduces labor intensity and ensures the positioning accuracy and working stability when replacing the nozzle.

2) Equipped with a complete control system, it can automatically change the nozzle model and specification according to different materials and plate thicknesses, reducing the time for manual replacement, thus improving production efficiency.

3) The automatic replacement nozzle is a fully enclosed protective device, which provides a good guarantee for nozzle equipment and personal safety.

3.6 lightning piercing and limit hole forming

(1) Lightning piercing

Short piercing time, small thermal focusing energy, stable starting point, and keeping the stability of the servo system can ensure the best cutting effect. See Table 2 for the advantages of lightning piercing.

(2) Limit hole

In the laser cutting industry, it has always been considered that the thickness of the plate is the minimum diameter of the cutting hole. The diameter of the minimum hole can be 0.15 times of the plate thickness or even smaller by the high-power laser cutting machine, as shown in Fig. 4.

04

Advantages of high power laser cutting machine

(1) High speed

The laser cutting speed has exceeded 20m / min, the two axis moving speed of the machining cutting machine can reach 250m / min, and the acceleration has reached about 10g during operation.

(2) High accuracy

In 1mm thick plate ϕ A small hole of about 10mm can cut about 500 holes per minute. The error between these small holes during cutting is very small.

(3) Develop towards thick plate

The power of the high-power laser cutting machine is gradually increased, and the size of the thick plate cut is also increasing.

(4) Develop towards large size

The processing size range of laser cutting technology is also increasing, and laser cutting technology has begun to develop in the direction of large size.

(5) Automatic unmanned

It is necessary and urgent to develop the automatic unmanned laser cutting technology. ① The application of computer network technology makes laser cutting technology realize automatic unmanned. ② The market demand for the application of this technology is also increasing, which urges the laser cutting technology to achieve full automation and unmanned.

(6) Intellectualization

Follow the pace of intelligent manufacturing according to the technical requirements of industry 4.0. Using accurate pattern recognition technology, simple operation procedures and convenient human-computer intelligent interaction, the laser is integrated with computer control, numerical control technology, optical system, high-precision and automatic positioning device, which integrates automatic material layout, cutting process database, remote fault diagnosis, remote control, etc., to meet the needs of large-scale and complex parts processing [3-4].

(1) Development of high power equipment

Laser cutting, as a very ideal cutting method, represents the development direction of modern metal processing technology. At present, high-power laser cutting machines are also carrying out key technology research and development in the fields of high speed, high precision, large format, three-dimensional cutting and special material cutting, so as to promote the development of high-power laser cutting technology to meet the growing market demand

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(2) Selection of high-power equipment

When choosing high-power laser cutting equipment, some enterprises need to consider carefully: in addition to cutting speed and accuracy, they should especially check the stability and consistency of full power continuous cutting, the speed matching ability of the machine tool, the progressiveness and precision life of the machine tool control. It is impossible to simply compare price factors like purchasing low-power laser cutting equipment. High power means high investment, and high investment implies high risk. When enterprises enter this high return market, they must recognize its risk.