The laser cutting machine is favored and purchased by most bosses because of its high precision, fast speed and low use cost. It gradually replaces the traditional production method and becomes the first productivity of "making money every day". With more and more orders for co processing, the variety and thickness of processing materials are more and more abundant. Some bosses will find that when cutting some thick plates, the cutting effect of finished products is not satisfactory.
The problems such as wide cutting seam, large cutting slope, non vertical cutting seam and slag hanging at the bottom hit one by one. What the hell is going on?
Reasons for Slopes of Cutting Seams of Thick Metal Plate Processed by Laser Cutting Machine
When the laser cutting machine is processing thick metal plates, its processing accuracy will become worse with the increase of the thickness of the plate to be cut, which will result in a large kerf, and the perpendicularity of the kerf will also become worse due to the large kerf, resulting in a kerf slope. When cutting thick plates with laser cutting machine, the gradient of finished products is mainly affected by two factors:
1. Focal length of processing lens;
2. Focus position;
【1】 Large focal depth and long focal length laser beam shall be used for thick plate cutting
The slit width of the laser cutting steel plate is directly related to the laser beam mode and the diameter of the focused spot. Because the energy density and power density of the laser beam are related to the diameter of the laser spot, in order to obtain a larger energy density and power density, the smaller the laser spot diameter is, the better.
The reduction of the focal length of the laser head focusing mirror is beneficial to the reduction of the spot diameter. However, as the focal length decreases, the focal depth becomes shorter. When cutting thick plates, the upper and lower parts of the plates are not conducive to obtaining equal width slits, which affects the quality of slits; At the same time, due to the reduction of focal length, the distance between the laser head and the plate is also reduced, and the slag spatter during cutting is easy to adhere to the laser head nozzle, affecting the cutting quality and the service life of the laser head. Therefore, this method is most suitable for high-speed cutting of thin plates, as long as the distance between the laser head and the plate is constant.
The focal length spot power density of the long focal length laser head is relatively low, but its focal depth is large, which can be used to cut thicker steel plates. Short focal length, small focus spot; The focal length is long, the focal spot is large, and the focal depth changes as well.
【2】 The thick plate shall be cut with proper focus
The smaller the laser beam focus, the greater the energy density, and the narrower the kerf. When the focus position is appropriate (as shown in the following figure), the plate at the focus is melted. At the same time, the plate near the focus (nearby) is not melted, and the slag is blown away. The formed slit is free of slag, and the upper slit width and slope are both minimum.
The figure shows the relationship between the focus position and the slope. The focus position Z is z=0 when machining the surface of the material. The moving distance (h) is expressed in millimeters (mm), which is positive (+) upward and negative (-) downward. When the focus position is set at the processing material surface (z=0), the upper slit width and slope are minimum; When the focus position moves up or down, the slope will expand.
It can be seen from the above two reasons that the width of the thick plate cutting slit is large and the perpendicularity of the cutting edge is poor because the beam from the laser of the original laser cutting machine can not reach the best conditions for thick plate cutting. In addition, if you want to achieve thick plate cutting, you also need a high-power laser cutting machine to assist you. The higher the power, the greater the thickness of the plate you can cut. If the user feels that it is necessary, he can contact the after-sales service personnel to increase the power of the laser cutting machine, replace the laser, the laser head and the water cooler, or choose to remove the thick plate processing order.