When laser welding equipment is welding, in order to maintain sufficient power density, the focus position is very important. The change of the relative position of the focal point and the workpiece surface directly affects the width and depth of the weld. In most laser welding applications, the focal point is usually set at approximately 1/4 of the desired penetration below the workpiece surface.
When laser welding different materials, the position of the laser beam controls the final quality of the weld, especially in the case of butt joints, which is more sensitive than that of lap joints. For example, when a hardened steel gear is welded to a low carbon steel drum, proper control of the laser beam position will facilitate the creation of a weld consisting primarily of low carbon components, which is more resistant to cracking. In some applications, the geometry of the workpiece to be welded requires the laser beam to be deflected by an angle. When the deflection angle between the beam axis and the joint plane is within 100 degrees, the workpiece's absorption of laser energy will not be affected.
Laser welding machine focus adjustment method:
1. Check the reference light source
The red semiconductor laser is the benchmark of the entire optical path, and its accuracy must be ensured first. Use a simple height gauge to check whether the red light is parallel to the top surface of the optical bench guide rail, and is on the centerline between the two guide rails of the optical bench. In case of deviation, it can be adjusted with 6 fastening screws. After adjustment, pay attention to check again whether all fastening screws are fully tightened.
2. Adjust the position of the output mirror (output dielectric diaphragm)
Before adjusting the output mirror, the condensing cavity with the YAG rod should be removed, so as not to affect the accuracy of the adjustment due to the refraction deviation of the YAG rod in the optical path. The exit hole that can fully reflect the red light back to the red light, otherwise it should be carefully adjusted by the knob of the diaphragm holder. Note that after the adjustment, the pin ring on the adjustment knob of the diaphragm holder should be completely locked to ensure the stability of its position, and then check again whether the position of the reflected light remains in the original position.
3. Check the installation position of the YAG rod
Paste the two ends of the YAG rod sleeves with transparent tape, and observe whether the red light spot is in the middle of the two rod sleeves. If there is any deviation, it should be corrected by adjusting the position of the optical cavity. Then observe the position of the reflected light of the YAG rod, which should be coincident with the exit hole of the red light. Otherwise, adjust the position of the concentrating cavity under the premise of keeping the red light in the center of the rod casing as much as possible, so that the reflected light is as close to the exit hole as possible. , at least ensure that the deviation from the exit hole is less than 1mm.
4. Adjust the position of the total reflection mirror (the total reflection dielectric diaphragm)
5. Check the position of the shutter