In recent years, the role of laser cutting machines in the sheet metal industry has become increasingly prominent. During the cutting process, there are six practical functions that, when properly utilized, can significantly improve the efficiency and performance of laser cutting machines.
Frog jumping is a rapid movement technique used in laser cutting machines. After cutting the first hole, the cutting head needs to move to the next cutting point. During this movement, the laser is turned off, and the cutting head moves without cutting, known as idle travel.
Early Technique: In early laser cutting machines, the idle travel consisted of three sequential actions: the cutting head would rise to a safe height, move horizontally to the next position, and then descend.
Improved Technique (Frog Jumping): To reduce idle travel time, these three actions are now performed simultaneously. The cutting head begins to rise as it moves horizontally and descends as it approaches the next position, following an arc-like trajectory similar to a frog's leap.
This advancement in laser cutting technology—frog jumping—only takes the time required for horizontal movement, eliminating the need for separate rise and fall times. Just as a frog leaps to catch its prey, the laser cutting machine's frog jump captures high efficiency. A modern laser cutting machine without frog jumping would be considered outdated.
When cutting different materials, the laser beam's focal point must be positioned at different locations on the workpiece's cross-section. This requires adjusting the focal point (focusing). Early laser cutting machines typically used manual focusing, but many modern machines have implemented automatic focusing.
Some might suggest that changing the height of the cutting head would suffice—raising the head to raise the focal point, or lowering it to lower the focal point. However, it's not that simple.
Explanation: During cutting, the distance between the nozzle and the workpiece (nozzle height) is about 0.5–1.5 mm, which is a fixed value. Therefore, focusing cannot be achieved by raising or lowering the cutting head. The focal length of the focusing lens is also fixed, so changing the focal length is not an option. Instead, moving the focusing lens itself can change the focal point: lowering the lens lowers the focal point, and raising the lens raises the focal point. This is one method of focusing, which can be automated by using a motor to move the focusing lens up and down.
Alternative Method: Another method of automatic focusing involves placing a variable curvature mirror (adjustable mirror) before the beam enters the focusing lens. By changing the curvature of the mirror, the divergence angle of the reflected beam is altered, thereby changing the focal point position.
Advantages: With automatic focusing, the efficiency of the laser cutting machine can be significantly increased: the time required for piercing thick plates is greatly reduced, and the machine can quickly adjust the focal point to the optimal position for cutting different materials and thicknesses.
When a sheet is placed on the worktable, it may be misaligned, potentially leading to material waste during cutting. If the angle of inclination and the origin of the sheet can be detected, the cutting program can be adjusted to match the sheet's angle and position, preventing waste. This is where the automatic edge detection function comes into play.
Process: After activating the automatic edge detection function, the cutting head starts and automatically detects three points on the two vertical edges of the sheet. Based on these points, the machine calculates the sheet's tilt angle and origin.
Benefits: This function saves the time previously spent adjusting the workpiece—moving a workpiece weighing hundreds of kilograms on the cutting table is no easy task—and improves the machine's efficiency.
Centralized piercing, also known as pre-piercing, is a processing technique rather than a machine function. When cutting thicker plates, each contour undergoes two stages: 1. Piercing, 2. Cutting. In the conventional process (piercing → cutting contour 1 → piercing → cutting contour 2 → ...), centralized piercing refers to performing all piercing operations on the entire sheet in advance, and then returning to cut all the contours.
Advantages: Centralized piercing prevents over-burning. During piercing of thick plates, heat accumulates around the piercing point. If cutting immediately follows piercing, over-burning can occur. With centralized piercing, after all piercings are completed and the machine returns to the starting point, there is sufficient time for the heat to dissipate, avoiding over-burning.
Centralized piercing also improves processing efficiency. In conventional processing, the focal point during piercing may not be at the optimal position, resulting in longer piercing times. With centralized piercing, the focal point can be set to the best position for piercing, then adjusted for cutting after piercing is complete, reducing piercing time by more than half.
Risks: However, centralized piercing has its risks. If a collision occurs during cutting, causing the sheet to shift, the uncut portion may be scrapped. Centralized piercing requires the assistance of an automated programming system.
During laser cutting, the sheet is supported by serrated strips. If a cut part is not small enough to fall through the gaps in the strips or large enough to be supported by them, it may become unbalanced and tilt. The cutting head, moving at high speed, may collide with it, causing a shutdown at best, or damage to the cutting head at worst.
Solution: The bridging (micro-connection) cutting process avoids this issue. When programming the laser cutting, certain closed contours are intentionally left partially uncut, so that after cutting, the parts remain attached to the surrounding material, preventing them from falling. These uncut sections are called bridges, or micro-connections.
Technique: The distance of the break, usually 0.2–1 mm, is inversely proportional to the thickness of the sheet. Advanced programming software can automatically add the appropriate number of bridges based on the contour length, distinguishing between inner and outer contours to ensure that waste (inner contour) falls off while the part (outer contour) remains attached to the parent material, eliminating the need for sorting.
If adjacent part contours are straight lines with the same angle, they can be combined into a single straight line, requiring only one cut. This is known as common edge cutting.
Advantages: Common edge cutting reduces the cutting length and can significantly improve processing efficiency. It also reduces the number of piercings, which further enhances the benefits.
Efficiency Example: If common edge cutting saves 1.5 hours per day, it saves approximately 500 hours per year. At a comprehensive cost of 100 yuan per hour, this equates to an additional 50,000 yuan in annual benefits.
Requirements: Common edge cutting relies on intelligent automatic programming software.