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Analysis of common problems of laser engraving machine

The boot has no action or the reset is not normal

Check to see if the machine LCD screen or fluorescent lamp is turned on/off. 

A: if not, check the power supply system or power fuse. 

B: if there is a display, check whether the light on the control board is on, if not, it means that the control board has no power supply, check whether there is something wrong with the switching power supply or abnormal power supply, if there is no fault of the switching power supply, it is the fault of the control board. 

Check the driver indicator. 

A: if it is not on, check whether the voltage output of the power supply switching power supply is normal, if it is abnormal, it is the fault of the switching power supply, or the switching power supply is not powered on. 

B: if the indicator light is on, check whether the motor wire connection is good. 

(Key points: power supply, fuse, control board card, driver, switching power supply, circuit)

The machine has no laser beam

Check the laser coming out of the laser tube if there is a laser in the laser tube. 

A: Check the laser intensity at the exit of the laser tube and clean the outlet of the laser tube. 

B: if it is found that the laser color in the laser tube is obviously abnormal, it can be basically determined that the laser tube is leaking or aging, and the laser tube should be replaced. 

If the laser color in the laser tube is normal and the intensity of the output port is normal, then adjust the optical path to test. 

If there is no light in the laser tube. 

A: check whether the circulating water is unobstructed. 

B: if the circulating water is unobstructed, the short water protection is tested. 

C: check whether the laser power supply is normal. 

D: check whether the wiring related to the laser power supply is reliable, and check along the cable to see if there is anything abnormal. 

E: replace the laser power supply or control board for testing. 

(Key points: laser tube, circulating water, water protection, laser power supply, signal line, control board card)

The carving is not deep, not fast, and the depth of the carving is different

The direct reason for the lack of laser processing depth and processing speed is that the effective power density of laser processing is low. 

For the same material, the processing effect of the laser mainly depends on the optical power density of the laser loaded on the processed material (note: not power), and the optical power density refers to the power per unit area. 

The calculation formula: laser power density = laser power/laser spot area. 

The following solutions can be classified into two categories: increasing the laser power or reducing the focus spot size. Increase the laser power at the final focus. 

1. Check and clean the light outlet of the laser tube

Check and clean the lenses. If the lenses are damaged, the lenses should be replaced in time. 

2. Check laser  path

 The laser path is correct and whether there are the following phenomena in the transmission process of the laser beam: 

The laser is partially obscured. 

When the laser passes through the hole, whether it passes through the center, and if it does not pass through the center, it is easy to cause a diffraction effect and reduce the laser power and mass. 

Increase the working current, but do not exceed the maximum working current of the laser tube, otherwise, the laser power will decrease, such as 80w 20mA, 130w: 22mA. 

3. The laser tube may be aging and needs to be replaced 

4. Upgrade to a higher-power laser tube 

Reducing the focus size: for most applications, reducing the spot size is more effective than increasing the working current of the laser tube or replacing a larger laser tube, and the cost is lower. 

The main factors that affect the focus spot size are as followed: 

Check the laser spot quality when incident into the focusing mirror: 

The better the quality of the laser spot incident into the focusing mirror, the smaller the focus size and the greater the optical power density. If it is found that the quality of the laser spot incident into the focusing mirror is poor, the following measures should be taken: 

Check from the exit hole of the laser tube to determine which link leads to the deterioration of the quality of the laser spot, and if it is caused by the mirror, adjust or replace the mirror. 

If the quality of the laser tube at the exit of the laser tube has become worse, the following measures should be taken: 

Check whether the length of the laser tube corresponds to the distance between the support points, and adjust the support points if necessary. 

The correct distance between the two support points is 1/2 of the length of the laser tube, with 1/4 protruding at both ends of the laser tube. 

It may be that the supporting direction of the laser tube is incorrect, which leads to the deformation of the laser tube and rotates the laser tube many times to find the best support angle (direction). 

Note: after rotating the laser tube, the installation adjustment of cooling water in and out should be re-carried out to maintain the principle of “low in and high out”. 

Whether the laser beam is always centered vertically when it is incident on the focusing lenses: 

When the laser beam is vertically and centrally incident on the focusing mirror, the focus quality is the best. If the laser beam is tilted into the focusing mirror, the focus quality will be greatly reduced, the focus size will increase sharply, and the optical power density will be greatly reduced, which will directly affect the power cutting quality. 

A. Carefully check and adjust the optical path of the lens to make the laser incident position at the four vertex corners fixed and reliable. only by reaching this standard can we ensure that the laser processing power density is stable in the whole working process. 

B. By using the optical path vertical calibration tool, the mirror is carefully checked and adjusted so that the laser beam is incident vertically into the focusing mirror in the focusing tube. 

Choose a focusing lens with appropriate focal length: 

For the same laser beam, the relationship between the focal length and the focus size of the focusing lenses is as follows: the shorter the focal length, the smaller the focus and the shorter the depth of field; the longer the focal length, the larger the focus, and the longer the depth of field, the larger the focus size and depth of field. 

The depth of field refers to the length of the laser power-dense area which can form the processing ability after laser focusing (figure). The longer the depth of field is, the more favorable it is to process thick material, but the focus becomes larger, and the cutting ability decreases. 

The smaller the depth of field, the smaller the focus size, which is beneficial to the cutting ability, but disadvantageous to the cutting depth. at the same time, it requires more flatness of the machining platform, that is, it becomes sensitive to the roughness of the platform. 

Therefore, the principle of selecting the focusing mirror is to use the focusing mirror with a shorter focal length as far as possible. 

The company now has many kinds of focus lenses, such as 38.1mm, 50.8 mm, 63.5mm focus 76.2mm, etc. When the cutting speed can not meet the needs of customers, the focus lens with a shorter focal length should be replaced. 

At the same time, customers are advised to be equipped with a variety of focusing lenses with different focal lengths to meet the processing requirements of different material thicknesses. 

Focus correctly and maintain an appropriate amount of defocus according to the actual situation: 

The focusing situation in the practical application should be carefully examined, and the correct focusing mode should be: 

Referring to the focal length value of the focusing mirror, after many experiments near this value, a point with the strongest processing ability is determined and applied as the correct focal length, even if it is the same lens, under the condition of different material and material thickness, the best focus position will also change, that is, for different materials and thickness, the amount of defocus is different. 

The amount of defocus: the focusing process of the laser is a process of gathering first and then gathering. 

In the process of divergence, in order to achieve the best cutting ability, the physical focus of the focusing mirror is completely coincident with the surface of the material, and the best processing effect can be obtained when the focus is adjusted to a certain depth of the material according to different conditions. the best processing effect can be obtained, this depth value is the amount of defocus, and the amount of defocus is related to the material and thickness of the material. 

After all the above efforts have failed, the laser tube or other accessories can be replaced. 

Check whether the voltage on the terminal board is normal, always connect the ammeter in the whole process, and observe whether the current is normal. 

(Key points: lens, laser tube power, focal length)

Automatic reset, halfway engraving, missed engraving, and random engraving in the process of work 

The main reasons are the control panel, loose connection line, unreliable motherboard, and grounding wire, and slight high voltage fire failure. 

1. Check the grounding condition of the machine and measure whether the ground wire is up to the standard (the resistance to the ground should not be more than 5 ohms). The ground wire needs to be modified to meet the relevant standards. 

2. Check to see if the connection cable is loose or the control panel button contact is bad. 

3. Whether there is a strong electric and magnetic close in the position of the machine. 

4. Check to see if there are any errors in the original drawing, such as crossing, unclosed, missing strokes, etc., correct the errors in the drawing, and then output the test. 

5. If there is no problem with the output of other graphics, it means that the graphics are wrong, and you need to re-export or remake the graphics. 

6. Check the laser tube or laser power supply to see if there is a fire or disconnect the laser power supply for testing. 

7. The problem still exists, replace the motherboard, computer testing. 

(Key points: a ground wire, control panel, connection cable, interference, graphics problem, high voltage ignition, laser power supply, control board card)

The laser is scattered, out of focus, and the lens tube overheated

1. The water temperature of the laser tube is too high. 

2. The lenses are seriously polluted. 

3. The position of the laser tube support is unreasonable, which causes the internal deformation of the tube. 

4. The light path deviates and the focusing effect is poor, which is the main reason for the heating of the focusing cylinder. 

5. The selection of the lens is unreasonable, and the processing depth is not taken into account when adjusting the focal length, which leads to a poor focusing effect. 

6. The quality of the laser tube. 

Inspection method: 

A. Ensure that the water temperature in the laser tube is below 30 degrees. 

B. Adjust the optical path to ensure that the optical path is correct, and the focal length adjustment must consider the processing depth. 

C. Customers are required to clean the lenses regularly to ensure that the lenses are pollution-free, and to choose a reasonable focusing mirror to ensure a good beam of light. 

D. Observe whether the position of the laser tube support is reasonable and adjust the support position. 

E. Replace the laser tube. 

(Key points: water temperature, lens, laser tube position, laser path, laser tube)

Continuous emission, intermittent glow, unstable or uncontrolled current

The main reasons are the wrong selection of laser type, motherboard, terminal board, power supply or control line connection, and the failure of the cooling water circulation system. 

Exclusion method: 

1. In the parameter setting, to see whether the type of laser is correct, it is the main cause of continuous luminous failure. 

2. 

Pull the signal cable between the laser power supply and the control board to see if it is loose and the connection is unreliable. 

3. Unplug the signal cable from the power supply and press the laser power supply button to analyze whether it is the power supply or the motherboard fault. 

4. The firing is normal, which means there is no fault in the power supply, and the firing is abnormal, which means that there is something wrong with the power supply. 

6. When the power supply is normal, connect the signal cable, use the multimeter to measure the switch control pin on the terminal, when the normal voltage is above 4 volts, less than 3 volts, the card output is abnormal; when luminous, the pin voltage should be less than 2 volts, higher than 2.5 volts output is not normal. 

7. Check to see if the water cycle is normal, whether the flow is occasional, and whether there is a problem with water protection. 

(Key points: parameters, signal line, laser power supply, control board card, water protection)

Daily maintenance of CO2 laser tube

Adjustment of laser path

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