How to prevent the tube fiber laser cutting machine cutting head protection mirror from cracking effectively

With the increasing popularity of 10,000-watt power cutting heads, we find more and more cases of protective lens cracking. Investigate its reason, mostly is caused by the pollution on the lens. When the power is increased to more than ten thousand watts, once the dust pollution on the lens appears, and the burning point is not stopped in time to deteriorate, the energy absorbed instantly increases, it is easy to appear the situation of cracking. Lenses bursting will cause a bigger problem for the cutting head. So today we will talk about measures that can effectively prevent the protective lens from cracking tube fiber laser cutting machine.

Cutting gas

About Piping Inspection

The gas path check is divided into two parts, one part from the gas tank to the gas outlet and the other part from the gas outlet to the cutting head to cut the gas connection.

Check point 1: cover the air outlet of the trachea with a clean white cloth and ventilate for 5-10 minutes to check the condition of the white cloth. Use a clean protective mirror or glass and place it in the air outlet of the trachea and ventilate at low pressure (5-6 bar) for 5-10 minutes to check whether there is water and oil in the protective mirror.

Check point 2: cover the air outlet of the trachea with a clean white cloth and ventilate for 5-10 minutes. Check the condition of the white cloth, use a clean protective mirror or glass, place the air outlet of the trachea and ventilate at low pressure (5-6 bar) for 5-10 minutes (ventilate for 20s; Stop 10s), check whether there is water and oil in the protective mirror; Whether there is an air hammer phenomenon.

Note: All trachea connections should use jacket-type fittings as far as possible, do not use quick connections as far as possible, and avoid 90° connections as far as possible. Try to avoid the use of raw material belt or thread glue, so as not to cause raw material belt fracture or thread glue debris into the gas path resulting in gas road pollution blocking proportional valve or cutting head, resulting in cutting instability or even cutting head lens burst. Customer is advised to install a high pressure high precision (1μm) filter at Checkpoint 1.

Gas path test: no light, empty the whole perforation, cutting process, protection mirror is clean.

2 Gas Requirements

Caution - cutting gas! Only clean and dry cutting gas is allowed and the maximum pressure of the laser head is 25 bar (2.5 MPa). The gas quality meets the requirements of ISO 8573-1:2010; Solid Particles - Level 2, Water - Level 4, Oil - Level 3

Requirements for cutting gas input pipes

The carburetor must be designed for the maximum gas consumption of all connected machine tools. The design of the pipe section from the carburetor to the connected machine tool must be as short as possible to avoid the use of hose connections to reduce the pressure difference, requiring the use of stainless steel pipe from the air source to the machine tool. Pressure reducing valves and filters must be installed on the air inlet of the connecting machine tool to protect the air path of the machine tool. Cylinder or cylinder group is not suitable for high-pressure nitrogen cutting.

4 cutting gas outlet requirements

Pre-blowing: before perforation (about 2S) out of air, connected to the proportional valve or IO plate 6 pin feedback, PLC monitoring to the cutting gas pressure to reach the set value, then out of light and perforation process, perforation process has been kept blowing. After the end of the perforation, the air has been out, down to the cutting with the position, this process does not stop air, the customer can change the air pressure from the perforation air pressure to cutting air pressure. Switch to perforation pressure when air movement, and keep the gas off, move to the next perforation point; After the cutting is finished, keep lifting the air, and stop the air after the delay of 2-3S.

Alarm signal connection

1PLC alarm connection

It is necessary to check whether the connection of alarm signal is correct during equipment debugging

The PLC interface first checks the alarm priority (second only to the emergency stop), the follow-up action Settings after the alarm (stop light, stop action).

No light check: take out the lower protective mirror drawer a little bit, appear LED4 alarm, PLC alarm input and follow-up action, laser will disconnect Laseron signal or under high pressure, stop the laser.

Light output check: the alarm signal of the 9th pin of the green IO board is unplugged, and whether the PLC has alarm information is checked to see whether the laser will be under high pressure and stop light output.

If the OEM has been connected to the alarm signal, the priority is second only to the emergency stop (fast transmission channel), the PLC signal response is very fast, can stop light in time, check other reasons. Some customers use Bochu system, did not receive alarm signal. The alarm interface needs to be customized and set subsequent actions (stop light, stop action) as follows:

2. Connection of optical coupler

If the PLC does not use a fast transmission channel, it is also possible to turn off the laser in a very short time. The cutting head alarm signal is directly connected with the optocoupler relay to control the Laseron signal (theoretically, it is also possible to control the laser safety interlock), and more directly cut off the light (laser enabled is also set to low - >; Laser off). However, to connect the alarm signal PIN9 to PLC in parallel, otherwise cutting head alarm, the customer does not know why, but the laser suddenly stopped light.

As for the temperature gradient, OEM should test and set it according to the actual cutting situation. The 6th pin of IO board should output the monitoring value of the protective mirror temperature (0-20mA) by default, and the corresponding temperature is 0-100 degrees. If the OEM wants to do it, it can do it.

Use original protective lenses

The use of non-original protective lenses can cause a number of problems, especially in the 10,000-watt cutting head.

1. The lens is not coated well or the material is too poor, which is easy to cause the temperature of the lens to rise too fast or the nozzle to get hot, resulting in unstable cutting, and in serious cases, the lens will burst;

2. Insufficient thickness or error in edge size will cause air leakage (air pressure alarm in the cavity) and pollute the protective mirror in the focusing module, leading to unstable cutting and impeneteness of cutting, and causing pollution of the focusing mirror in serious cases;

3. The cleanliness of the new lens is not enough, resulting in frequent burnout of the lens, pollution of the protective lens in the focusing module, and the lens bursting in serious cases.