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Secrets of laser cutting machine technology
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Secrets of laser cutting machine technology

Secrets of laser cutting machine technology

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(Summary description)1.Frog Hopping Frog Hopping is the emptying method of the laser cutter.  The cutting head moves from point A to point B. Of course, the laser is turned off during the process. The process of movement from point A to point B, the machine "empty" run, known as empty travel. In the early days of laser cutting machines, the cutting head had to perform three actions in the empty run: rise (to a safe enough height), flat (to reach the top of point B), and fall. Compressing the air travel time increases the efficiency of the machine. It is possible to shorten the idle time if the three actions are completed "simultaneously": when the cutting head moves from point A to point B, it rises at the same time; when it approaches point B, it falls at the same time. 

Secrets of laser cutting machine technology

(Summary description)1.Frog Hopping Frog Hopping is the emptying method of the laser cutter.  The cutting head moves from point A to point B. Of course, the laser is turned off during the process. The process of movement from point A to point B, the machine "empty" run, known as empty travel. In the early days of laser cutting machines, the cutting head had to perform three actions in the empty run: rise (to a safe enough height), flat (to reach the top of point B), and fall. Compressing the air travel time increases the efficiency of the machine. It is possible to shorten the idle time if the three actions are completed "simultaneously": when the cutting head moves from point A to point B, it rises at the same time; when it approaches point B, it falls at the same time. 

Information

1.Frog Hopping

        Frog hopping is the air-jumping method of the laser cutter, which is used to cut hole 1 and then hole 2.

        The cutting head moves from point A to point B. Of course, the laser is turned off during the process. The process of movement from point A to point B, the machine "empty" run, known as empty trip.

       In the early days of laser cutter blanking, the cutting head had to perform three actions secondarily: rising (to a safe enough height), leveling (to reach above point B), and descending.

       Compressing the idle time will increase the efficiency of the machine. If the three sequential actions are performed "simultaneously", the idle time can be shortened: when the cutting head moves from point A to point B, it rises at the same time; when it approaches point B, it falls at the same time.

       The trajectory of the cutting head's airborne motion is like an arc drawn by a frog jumping.

        In the development of laser cutting machines, frog hopping counts as a prominent technological advancement. The frog jumping action only takes up the time from point A to point B flat movement, eliminating the time of ascent and descent. Frog jump, catch the food; laser cutting machine's frog jump, "catch" to the high efficiency.

        If the laser cutting machine now does not have the frog jump function, I'm afraid that it is not into the flow.

2.Auto Focus

    Cutting different materials requires the laser beam to be focused at different locations on the cross-section of the workpiece. 

    Therefore, it becomes necessary to adjust the position of the focus (focus). Earlier laser cutting machines were generally manually focused; nowadays, many manufacturers have automated focus on their machines.

    One might say that changing the height of the cutting head is fine; if the cutting head rises, the focus position is high, if the cutting head lowers, the focus position is low. It's not that simple.

    The bottom of the cutting head is the nozzle. During the cutting process, the distance between the nozzle and the workpiece (nozzle height) is about 0.5 to 1.5mm, which may be regarded as a fixed value, i.e., the nozzle height remains unchanged, so the focus cannot be adjusted by raising and lowering the cutting head (otherwise the cutting process cannot be completed).

    The focal length of the focusing mirror is not changeable, so you cannot expect to focus by changing the focal length either.

    If you change the position of the focusing lens, you can change the position of the focus: if the focusing lens goes down, the focus goes down, if the focusing lens goes up, the focus goes up. -- this is indeed one way to adjust focus. Auto focus can be achieved by using a motor to drive the focusing mirror in an up and down motion.

    Another method of autofocusing is to change the focus position by placing a variable curvature mirror (or adjustable mirror) before the beam enters the focusing mirror, which changes the angle of divergence of the reflected beam by changing the curvature of the mirror.

    With the auto focus function, can significantly improve the processing efficiency of the laser cutting machine: thick plate perforation time is greatly reduced; processing different materials, different thickness of the workpiece, the machine can automatically and quickly adjust the focus to the most appropriate position.

3.Automatic edge finding

    When the sheet is placed on the table, if it is tilted, it can cause waste when cutting.

    If it is possible to sense the angle of inclination and origin of the sheet, it is possible to adjust the cutting process to fit the angle and position of the sheet, thus avoiding waste. The automatic edge finding function is the result.

    When the auto-edge function is activated, the cutting head automatically measures 3 points on the two vertical sides of the sheet from point P: P1, P2 and P3, and then automatically calculates the angle of inclination A of the sheet, as well as the origin of the sheet.

    Thanks to the automatic edge finding function, the time spent earlier on adjusting the workpiece is eliminated - not an easy task when adjusting (moving) workpieces weighing hundreds of kilograms on the cutting table. This increases the efficiency of the machine.

4. Central piercing

    Concentrated piercing, also known as pre-piercing, is a process that is not a function of the machine itself.

    When laser cutting thicker plates, each contour of the cutting process undergoes two stages: 1. piercing and 2. cutting.

    Conventional machining process (point A perforation → cutting profile 1 → point B perforation → cutting profile 2 → ......)

    Centralized perforation means that all perforations on the entire board are performed centrally in advance, and then the cutting process is carried out later.

    Concentrated piercing process (complete piercing of all contours → return to starting point → cut all contours)

    The total trajectory length of the machine is increased in the case of concentrated piercing compared to the conventional machining process. So why do we need centralized piercing?

    Concentrated piercing can avoid overheating. During the piercing process of the thick plate, heat is collected around the piercing point, and if it is followed by cutting, the overheating phenomenon will occur. With the centralized piercing process, when you finish all the piercing and return to the starting point to cut again, you have enough time to dissipate heat, so you can avoid the overheating phenomenon.

    Centralized piercing can improve processing efficiency. Currently, there are still many laser cutting machines that do not have auto-focusing. With thick plates, the process parameters (laser mode, power, nozzle height, auxiliary gas pressure, etc.) are different in the piercing and cutting stages. The nozzle height is higher in the piercing process than in the cutting process. If the conventional process is taken (Profile 1 piercing → Profile 1 cutting → Profile 2 piercing → Profile 2 cutting → ......), in order to ensure cutting quality and efficiency, the focus of the laser beam can only be manually adjusted to the optimum position required for cutting (imagine if: at the beginning, the focus is manually adjusted to the position required for piercing. (The piercing; then the focus is adjusted to the desired position for the cut; the cut; then the piercing position; the piercing; ......; until the process is complete - it's a nightmare). As a result, the focal point for piercing will necessarily not be in the optimal position and the piercing time will be longer. However, if you take the centralized piercing method, you can first adjust the focal point to a position suitable for piercing, and then, after the piercing is completed, pause the machine and adjust the focal point position to the best position required for cutting; in this way, the piercing time can be shortened by more than half, greatly improving efficiency. Of course, if necessary, other process parameters can also be adjusted or changed in the middle of concentrated piercing and cutting (for example, air + continuous wave can be used for piercing, while using oxygen for cutting, there is enough time to complete the gas switch in the middle). We generally refer to the automatic zoom driving the focal lens as the F-axis; is it possible to call this "H" (Hand) axis "zoom" when using manual zoom for concentrated piercing and cutting like this?

Concentrated perforation is also a risk. If a collision occurs during the cutting process, causing the sheet to change position, the uncut part may be scrapped.

     The centralized piercing process requires the help of an automatic programming system.

5. Bridging (micro-connections)

    During the laser cutting process, the sheet is held in place by a jagged support bar. If the cut part is not small enough to fall through the gap in the support bar, or large enough to be held by the bar, it may lose its balance and warp. A cutting head moving at high speed may collide with it, stopping or damaging the cutting head.

    This phenomenon can be avoided by the bridge (micro-joint) cutting process.

    When programming a laser cut to a pattern, the closed contour is intentionally broken at several points so that the part stays attached to the surrounding material and does not fall off after the cut has been made - these breaks are called bridges. Also known as a breakpoint, or micro-joint (a term derived from a rigid translation of Micro Joint). The distance of the break, about 0.2 to 1mm, is inversely proportional to the thickness of the sheet. Based on different angles, there are these different names: based on the profile, disconnected, so called breakpoint; based on the part, bonded to the base material, so called bridging or micro-joint.   

The sophisticated programming software automatically adds the appropriate number of bridges according to the length of the contour. It is also possible to distinguish between the inner and outer contours and decide whether to add bridges or not, so that the inner contours (scrap) without bridges will fall off and the outer contours (parts) with bridges will be stuck together with the base material and not fall off, thus eliminating the need for sorting.

6. Common edge cutting

    If the contours of adjacent parts are straight and have the same angle, they can be combined into one straight line and cut only once. This is known as a common edge cut. Obviously, cutting with a common edge reduces the length of the cut and significantly increases the efficiency of the process.

    The common cut does not require the part to be rectangular in shape.

The benefits of cutting on the common side are obvious, as it not only saves time in cutting, but also reduces the number of perforations. If 1.5 hours are saved per day due to common edge cutting, that's about 500 hours per year, which equates to an additional $50,000 per year at a combined cost of $100 per hour.

    Common edge cutting relies on intelligent, automatic programming software.

Reprinted from the Unity Prema website (http://www.unityprima.com/news_detail/newsId=188.html)

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