Special-shaped materials, such as square tubes, rectangular tubes, oval tubes, flat tubes, U-shaped tubes, channel steels, I-beams, etc., are widely used in the furniture industry, display shelves, etc. due to their beautiful appearance, good strength and mechanical properties. Fitness equipment, sheet metal processing, decorative advertising, kitchenware and bathroom, household appliances, agricultural and forestry machinery and other fields. These pipes usually need to be connected accordingly to form a variety of entities. The connection between two or more pipes is called pipe intersection in drawing geometry and engineering drawing, and the curve formed at the intersection is called intersection. Wire. Where pipes intersect, holes need to be drilled into the pipes, pipe fittings with larger wall thicknesses (greater than 6mm) need to be connected, and welding grooves need to be cut to ensure stable pipe welding and reliable quality. In the past, most of the processing of pipe intersecting lines was done manually, with low processing efficiency, uneven processing quality, and high technical requirements for workers. With the rapid development of industrialization, CNC cutting machines have gradually replaced manual cutting, thus greatly improving processing efficiency and steadily improving processing quality. Because laser cutting has the characteristics of high cutting efficiency, wide cutting range, small heat-affected zone, and good processing flexibility, laser cutting machines are widely used in cutting special-shaped pipe fittings.
Laser cutting principle
Laser cutting is achieved by using laser focus to produce high-power energy. Under the action of the computer control system, the laser generator achieves the purpose of discharge through certain pulses, and then outputs a controlled and continuous high-frequency pulse laser to form a laser beam of specific frequency and pulse width. This beam passes through transmission, reflection and focusing lenses. By focusing, the laser beam appears on the surface of the material to be processed in the form of tiny, high-energy-density spots, causing the material to be processed to melt or vaporize at high temperatures in an instant. A single high-energy-density laser pulse can instantly sputter a smaller hole on the surface of the material to be processed. Under the action of continuous laser pulses, the laser cutting head and the material to be processed perform corresponding movements according to a preset motion control algorithm. , so that materials of predetermined shapes can be processed. During laser cutting, an airflow coaxial with the laser beam is ejected from the laser cutting head, which discharges the heated, melted or vaporized material at the bottom of the cut.
Factors affecting laser cutting
1) Laser power
Laser power is one of the more important factors affecting laser cutting. For a pipe of a specific material, a certain laser power has a certain optimal cutting speed corresponding to it. The greater the laser power, the wall thickness of the cut pipe will also increase accordingly, but the width of the pipe slit and the heat-affected zone will also become larger, which is prone to end-face ablation. The difference is that the corresponding change trend of the notch end surface corrugation and surface roughness is not very obvious.
2) Cutting speed
When the laser cutting power is at a specific value, different cutting speeds correspond to different slag hanging on the back of the pipe and different cutting seam quality. When the pipe can be cut through, the longer the laser irradiates the pipe, the slower the cutting speed, and the larger the corresponding heat-affected zone, so the cutting seam is relatively rough and there is more slag. Within a certain range, the faster the cutting speed, the better the kerf quality; when the laser cutting speed exceeds a certain value, the auxiliary cutting gas has no time to blow away the kerf slag, resulting in the corresponding kerf slag not being removed, resulting in The cuts are rough. For a specific material, when other conditions such as laser cutting power are constant, there will be a corresponding optimal cutting speed. If the optimal cutting speed can be maintained during laser processing, the cutting quality will be better.
3) Focus position
The focus position affects the incision width, slag hanging situation and cut surface roughness of laser cutting pipes. The reason for this influence is that as the focus position of the laser beam changes, the laser beam and focus depth on the surface of the material to be processed change, thus changing the shape of the processing groove. Subsequent changes occur, correspondingly affecting the flow of molten metal and auxiliary gas in the processing trench.
Intersecting line cutting principle
Common special-shaped materials include square tubes, rectangular tubes, elliptical tubes, flat tubes, I-beams, etc. Since the cutting of intersecting lines of tubes is the most complicated, the principle of intersecting line cutting formed by tube-to-tube intersections is mainly analyzed. Intersecting line cutting can be divided into intersecting lines with bevels and without bevels. Intersecting line cutting with bevels requires the largest number of linkage axes, which mainly include the laser cutting head floating up and down, swinging around the Z axis, moving along the Y axis and The workpiece moves and rotates along the axis, and the intersection line with the groove can be cut through the linkage of the four coordinate axes.
Laser cutting machine cutting principle
When the laser cutting machine processes the intersecting line without a groove, the pipe fitting rotates around itself A, the laser cutting head translates along the Y-axis and floats up and down along the Z-axis to complete the processing of the intersecting line; when the laser cutting machine processes the intersecting line with a groove When intersecting lines, the processing of the intersecting lines is completed through the rotation movement A of the pipe around itself, the translation of the laser cutting head along the Y axis, the up and down movement of the Z axis, and the swing W around the Z axis.
Laser cutting machine mechanical structure
The laser cutting machine is mainly composed of three parts: mechanical transmission system, electrical control system and host computer software system. The mechanical transmission system is the main body of the laser cutting machine, and the design of the mechanical structure is related to the geometry of the pipe to be processed.
Laser cutting head movement
The movement of the laser cutting head is divided into three parts: the cutting head floats up and down along the Z-axis, moves along the Y-axis, and swings around the Z-axis. Among them, the laser cutting head floats up and down and moves along the Y-axis using a servo motor to drive the ball screw, and the swing around the Z-axis is driven by a disc motor.
Conclusion
The utilization of laser cutting technology for processing special-shaped materials, particularly in the fabrication of intersecting lines of pipes, marks a significant advancement in manufacturing. Laser cutting offers precise and efficient cutting capabilities, improving processing efficiency and ensuring high-quality results. Factors such as laser power, cutting speed, and focus position play crucial roles in determining the quality of laser cutting. The intricate maneuvers involved in cutting intersecting lines, including pipe rotation and laser head movement, demonstrate the complexity of the process and the versatility of laser cutting machines. The mechanical structure of laser cutting machines, comprising transmission systems, electrical controls, and software, is tailored to accommodate the diverse geometric shapes of the materials being processed. Overall, laser cutting technology represents a pivotal innovation in modern manufacturing, facilitating the production of intricate components with precision and reliability across various industries.
