As the relative position of the beam and the workpiece moves, the material will finally form a slit, so as to achieve the purpose of cutting.
Laser cutting processing is to replace the traditional mechanical knife with an invisible beam. It has the characteristics of high precision, fast cutting, not limited to the cutting pattern, automatic typesetting, saving materials, smooth cutting, and low processing cost. It will gradually improve or replace it. Traditional metal cutting process equipment. The mechanical part of the laser cutter head has no contact with the workpiece, and will not scratch the surface of the workpiece during work; the laser cutting speed is fast, the incision is smooth and flat, and generally does not need subsequent processing; the cutting heat affected zone is small, the plate deformation is small, and the slit is narrow ( 0.1mm~0.3mm); the incision has no mechanical stress, no shearing burr; high processing accuracy, good repeatability, and no damage to the surface of the material; CNC programming, can process any plan, and can cut large-format whole plates without Opening the mold saves time and economy.
Compared with traditional oxyacetylene, plasma and other cutting processes, laser cutting speed is fast, the slit is narrow, the heat-affected zone is small, the edge of the slit is perpendicular, and the cutting edge is smooth. At the same time, there are many types of materials that can be laser cut, including carbon steel. , Stainless steel, alloy steel, wood, plastic, rubber, cloth, quartz, ceramics, glass, composite materials, etc. With the rapid development of the market economy and the rapid development of science and technology, laser cutting technology has been widely used in automobiles, machinery, electricity, hardware, and electrical appliances. In recent years, laser cutting technology is developing at an unprecedented speed, with an annual growth rate of 15% to 20%. Since 1985, my country has grown at a rate of nearly 25% per year. At present, the overall level of laser cutting technology in my country still has a big gap compared with advanced countries. Therefore, laser cutting technology in the domestic market has broad development prospects and huge application space.
During the cutting process of the laser cutting machine, the beam is focused by the lens of the cutting head into a small focal point, so that the focal point can reach a high power density, and the cutting head is fixed on the z-axis. At this time, the heat input by the beam far exceeds the part of the heat reflected, conducted or diffused by the material, and the material is quickly heated to the melting and vaporization temperature. At the same time, a high-speed airflow will melt from the coaxial or non-coaxial side. And the vaporized material is blown out to form holes for cutting the material. With the relative movement of the focus and the material, the hole forms a continuous slit with a very narrow width to complete the cutting of the material.
Currently, the outer optical path part of the laser cutting machine mainly uses the flying optical path system. The light beam emitted from the laser generator reaches the focusing lens on the cutting head through the reflecting mirrors 1, 2, and 3, and forms a light spot on the surface of the material to be processed after focusing. The reflecting lens 1 is fixed on the fuselage without moving; the reflecting mirror 2 on the beam moves in the x direction with the movement of the beam; the reflecting lens 3 on the z axis moves in the y direction with the movement of the z axis. It is not difficult to see from the figure that in the cutting process, as the beam moves in the x direction and the z axis moves in the y direction, the length of the light path changes every moment.
Due to the manufacturing cost and other reasons, the laser beam emitted by the civilian laser generator has a certain divergence angle and is "conical". When the height of the "cone" changes (equivalent to a change in the optical path length of the laser cutting machine), the cross-sectional area of the beam on the surface of the focusing lens also changes. In addition, light also has the properties of waves. Therefore, diffraction phenomenon will inevitably occur. Diffraction will cause the beam to expand laterally during propagation. This phenomenon exists in all optical systems and can determine the performance of these systems. Limit value. Due to the "cone" of the Gaussian beam and the diffraction of light waves, when the length of the optical path changes, the diameter of the beam acting on the lens surface changes all the time, which will cause changes in the focus size and depth, but affect the focus position Very small. If the focus size and focus depth change during continuous processing, it will inevitably have a great impact on the processing. For example, it will cause inconsistent cutting slit widths, incomplete cutting or ablation of the board under the same cutting power.
Laser is a kind of light, like other natural light, it is produced by the transition of atoms (molecules or ions, etc.). However, it is different from ordinary light in that the laser only relies on spontaneous emission for a very short period of time, and the subsequent process is completely determined by the excitation radiation. Therefore, the laser has a very pure color, almost no divergence, and extremely high luminous intensity. And high coherence.
Laser cutting is achieved by applying high power density energy generated by laser focusing. Under the control of the computer, the laser is discharged through pulses to output a controlled repetitive high-frequency pulsed laser to form a beam with a certain frequency and a certain pulse width. The pulsed laser beam is guided and reflected by the optical path and focused by the focusing lens group. On the surface of the processed object, a small, high-energy-density light spot is formed. The focal spot is located near the surface to be processed and melts or vaporizes the processed material at an instant high temperature. Each high-energy laser pulse instantly sputters a small hole on the surface of the object. Under computer control, the laser processing head and the processed material perform continuous relative movement according to the pre-drawn graphics, so that the object will be processed into The shape you want.
The process parameters (cutting speed, laser power, gas pressure, etc.) and motion trajectory during slitting are controlled by the numerical control system, and the slag at the slit is blown away by a certain pressure of auxiliary gas.
1. High precision: suitable for cutting precision parts and fine cutting of various craftsmanship and paintings.
2. Fast speed: more than 100 times that of wire cutting.
3. The heat affected zone is small and not easy to deform. The cutting seam is smooth and beautiful, without subsequent processing.
4. High cost performance: The price is only 1/3 of the same performance CO2 laser cutting machine, and 2/5 of the same performance CNC punch.
5. The use cost is very low: only 1/8~1/10 of similar CO2 laser cutting machine, the hourly cost is only about 18 yuan, and the hourly cost of CO2 laser cutting machine is about 150-180 yuan.
6. The follow-up maintenance cost is very low: only 1/10～1/15 of the similar CO2 laser cutting machine, and 1/3～1/4 of the equivalent CNC punching machine.
7. Stable performance to ensure continuous production. The solid-state YAG laser is one of the most stable and mature products in the laser field.
8. Compared with CNC punching machine, YAG laser cutting machine has the following advantages:
(1) It can complete the processing of various complex structures. As long as any image can be drawn on the computer, the machine can complete the processing.
(2) There is no need to open the mold, just make the drawing on the computer, and the product can be released immediately, which can quickly develop new products and save costs.
(3) The YAG cutting machine has an automatic tracking system, so it can complete plane cutting as well as various uneven curved surfaces.
(4) The complex process requires that the CNC punch is difficult to complete, and laser cutting can do it.
(5) The surface is very smooth and the product grade is very high, which is difficult for CNC punching machines.
(6) The molded box (within 0.5 meters in thickness) needs to be processed with holes and grooves, which cannot be processed by CNC punching machine, but YAG CNC metal laser cutting machine can solve it.
⒈1Vaporization cutting: In the laser vaporization cutting process, the speed of the material surface temperature rising to the boiling point temperature is so fast that it is enough to avoid melting caused by heat conduction, so part of the material vaporizes into steam and disappears, and part of the material is discharged from the cutting The bottom of the slit is blown away by the auxiliary gas flow. In this case, very high laser power is required. In order to prevent material vapor from condensing on the slit wall, the thickness of the material must not greatly exceed the diameter of the laser beam. This process is therefore only suitable for applications where the removal of molten material must be avoided. This processing is actually only used in areas where iron-based alloys are very small. This process cannot be used for materials such as wood and certain ceramics that are not in a molten state and are therefore unlikely to recondense the material vapor. In addition, these materials usually require thicker cuts. In laser gasification cutting, the optimal beam focus depends on the material thickness and beam quality. The laser power and the heat of vaporization have only a certain influence on the optimal focus position. In the case of a certain sheet thickness, the maximum cutting speed is inversely proportional to the vaporization temperature of the material. The required laser power density is greater than 108W/cm2 and depends on the material, cutting depth and beam focus position. In the case of a certain sheet thickness, assuming sufficient laser power, the maximum cutting speed is limited by the gas jet speed.
⒉ Melting cutting: In laser melting cutting, the workpiece is partially melted and the molten material is sprayed out with the help of airflow. Because the transfer of the material only occurs in its liquid state, the process is called laser melting and cutting. The laser beam is matched with high-purity inert cutting gas to drive the melted material to leave the kerf, and the gas itself does not participate in the cutting. Laser melting cutting can get a higher cutting speed than gasification cutting. The energy required for gasification is usually higher than the energy required to melt the material. In laser melting and cutting, the laser beam is only partially absorbed. The maximum cutting speed increases with the increase of laser power, and decreases almost inversely with the increase of sheet thickness and material melting temperature. In the case of a certain laser power, the limiting factors are the air pressure at the slit and the thermal conductivity of the material. Laser melting and cutting can obtain oxidation-free incisions for iron materials and titanium metals. The laser power density that produces melting but not gasification is between 104 W/cm2 and 105 W/cm2 for steel materials.
⒊Oxidation melting and cutting (laser flame cutting): Generally, inert gas is used for melting and cutting. If oxygen or other active gases are used instead, the material will be ignited under the irradiation of the laser beam, and a fierce chemical reaction with oxygen will generate another heat source. , So that the material is further heated, called oxidation melting cutting. Due to this effect, for structural steel of the same thickness, the cutting rate that can be obtained by this method is higher than that of melting cutting. On the other hand, this method may have worse cut quality compared to fusion cutting. In fact, it will produce wider kerf, obvious roughness, increased heat-affected zone and worse edge quality. Laser flame cutting is not good when processing precision models and sharp corners (there is a danger of burning the sharp corners). A pulsed laser can be used to limit the thermal influence, and the power of the laser determines the cutting speed. In the case of a certain laser power, the limiting factor is the supply of oxygen and the thermal conductivity of the material.
⒋Controlled fracture cutting: For brittle materials that are easily damaged by heat, high-speed and controllable cutting is performed by laser beam heating, which is called controlled fracture cutting. The main content of this cutting process is: the laser beam heats a small area of brittle material, causing a large thermal gradient and severe mechanical deformation in this area, causing the material to form cracks. As long as a uniform heating gradient is maintained, the laser beam can guide cracks in any desired direction.
Cutting accuracy is the first element to judge the quality of a CNC laser cutting machine. Four factors affecting the cutting accuracy of CNC laser cutting machines:
⒈ The size of the laser condensed laser generator. If the light spot is very small after gathering, the cutting accuracy is very high, and the gap after cutting is also very small. It shows that the precision of the laser cutting machine is very high, and the quality is very high. But the beam emitted by the laser is cone-shaped, so the slit cut out is also cone-shaped. Under this condition, the greater the thickness of the workpiece, the lower the accuracy, so the larger the slit.
⒉The accuracy of the workbench. If the accuracy of the table is very high, the accuracy of cutting will also be improved. Therefore, the accuracy of the workbench is also a very important factor to measure the accuracy of the laser generator.
⒊ The laser beam is condensed into a cone. When cutting, the laser beam is tapered downwards. At this time, if the thickness of the cut workpiece is very large, the cutting accuracy will be reduced, and the cut gap will be very large.
⒋Different materials to cut will also affect the accuracy of the laser cutting machine. Under the same circumstances, the accuracy of cutting stainless steel and aluminum will be very different, the cutting accuracy of stainless steel will be higher, and the cut surface will be smoother.
Generally speaking, the quality of laser cutting can be measured by the following 6 standards.
⒈Cutting surface roughness Rz
⒉ Cutting slag size
⒊ Cutting edge perpendicularity and slope u
⒋Cutting edge round corner size r
⒌ Drag after stripes n
⒍ Flatness F
The application of metal laser cutting machine is very extensive, covering many industries, and it is one of the necessary equipment for many companies, including advertising sign production (these are mainly stainless steel LOGO and logo cutting), sheet metal processing (sheet Metal processing basically includes all metal materials. These generally include bending, polishing, etc., and cutting is the most important process), chassis and cabinet production (in this regard, carbon steel or stainless steel is generally useful, but also mainly folding Bending and cutting 2 cutting processes), springs (belonging to the finishing process), subway parts, and the production of elevator casings, mechanical equipment casings, and kitchen utensils (mostly stainless steel), which surpass lasers The laser cutting machine setting of the company also participated in the production of the Seven Gods Eight Spacecraft, which actually involves various aspects. Widely used in sheet metal processing, advertising sign production, high and low voltage electrical cabinet production, mechanical parts, kitchenware, automobiles, machinery, metal crafts, saw blades, electrical parts, glasses industry, springs, circuit boards, electric kettles, medical micro Electronics, hardware, knife measuring tools and other industries.
⒈ The dual-focus laser cutting head is a fragile item on the laser cutting machine. Long-term use will damage the laser cutting head.
⒉ Check the straightness of the fiber laser cutting machine track and the verticality of the machine every six months, and if it is found to be abnormal, it will be maintained and debugged in time. If this is not done, the cutting effect may not be so good, the error will increase, and the cutting quality will be affected. This is the top priority and must be done.
⒊ Use a vacuum cleaner to suck up dust and dirt from the machine once a week, and all electrical cabinets should be closed and dustproof.
⒋ Check the steel belt of the fiber laser cutting machine frequently to ensure that it is tight. Otherwise, if something goes wrong during the operation, people may be injured, or even death may be serious. The steel belt looks like a small thing, but the problem is still a bit serious.
⒌ The guide rails of the fiber laser cutting machine should be cleaned frequently to remove dust and other debris to ensure that the equipment is normal. The rack should be wiped frequently and lubricated to ensure lubrication without debris. The guide rails should be cleaned and lubricated frequently, and the motor should also be cleaned and lubricated frequently. The machine can move better and cut more accurately, and the quality of the cut products will be improved.