The application and introduction of laser cutting machine part.3

1) industrial application

Metal laser cutting machine is very widely used, a lot of industry, and is a lot of enterprises must be one of the necessary equipment, including advertising signs production (the main is some of the LOGO and label cutting of stainless steel), sheet metal processing, sheet metal processing contains basic all of metal materials, the general is mainly bending, grinding, such as cutting is one of the most important procedure), chassis cabinets production (generally useful to carbon steel or stainless steel, this also is mainly bending and cutting two cutting process), spring (to finish machining process), the parts, and the elevator casing production o.Shell, mechanical equipment and kitchen utensils (mostly in the stainless steel), are widely used in sheet metal processing, advertisement sign word production, the production of high and low voltage electrical cabinets, machinery parts, kitchen utensils and appliances, automobiles, machinery, metal crafts, saw blade, electrical parts, glasses industry, leaf spring, circuit board, electric kettle, healthcare, microelectronics, hardware, knives, measuring tool, etc.

The application of laser machining technology in advertising industry mainly includes laser cutting and laser engraving.

Laser engraving: mainly on the surface of the object, divided into bitmap engraving and vector engraving:

Bitmap carving: we first in PHOTOSHOP we need to carve the graphics for net processing and into monochrome BMP format, and then in the special laser engraving cutting software to open the graphics file.According to the material we process, we can set the appropriate parameters, and then click to run, the laser engraving machine will be engraved according to the graphics file produced by the lattice effect.

Vector engraving: use vector software such as Coreldraw, AutoCad, Iluustrator and other typesetting design, and export the graphics into PLT, DXF, AI format, marking machine, and then use the special laser cutting and engraving software to open the graphics file, send it to the laser engraving machine for processing.

In the advertising industry is mainly applicable to the processing of wood, double - color board, plexiglass, colored paper and other materials.

Laser cutting: we can understand as the separation of the edge.For such processing purposes, we should first make the graphics into the form of vector lines in CORELDRAW and AUTOCAD, and then save them into the corresponding PLT and DXF formats, open the file with the operation software of the laser cutting machine, and then run it after setting the parameters such as energy and speed according to the materials we process.The laser cutting machine receives instructions from a computer and automatically cuts according to the flight path generated by the software.

2) material analysis

Structural steel:

Better results are obtained when the material is cut with oxygen.When oxygen is used as a processing gas, the cutting edge is slightly oxidized.Nitrogen can be used as a processing gas for high-pressure cutting of plates with thickness up to 4mm.In this case, the cut edge will not be oxidized.The thickness of the plate is more than 10mm, the use of special plate for the laser and in the processing of the workpiece surface oil can get a better effect.

Stainless steel:

Cutting stainless steel requires: the use of oxygen, in the case of marginal oxidation does not matter;Nitrogen is used to get a no-oxidation, no-burr edge, and no further treatment is required.Coating the oil film on the surface of the plate will get better perforation effect without reducing the processing quality.

Aluminum:

Despite its high reflectivity and thermal conductivity, aluminum with a thickness of less than 6mm can be cut, depending on the alloy type and laser capability.When cut with oxygen, the cutting surface is rough and hard.When nitrogen is used, the cutting surface is smooth.Pure aluminum, because its high purity is very difficult to cut, should only be cut when a "reflection and absorption" device is installed on the system.Otherwise the reflection will destroy the optical component.

Ti:

Titanium plates are cut using argon and nitrogen as the processing gas.Other parameters can be referred to nickel-chromium steel.

Copper and brass:

Both materials have high reflectivity and excellent thermal conductivity.Brass up to 1mm thick can be cut with nitrogen;Copper with a thickness of less than 2mm can be cut, and oxygen must be used to process gas.Copper and brass should be cut only when a "reflection and absorption" device is installed on the system.Otherwise the reflection will destroy the optical component.

Synthetic materials:

Keep in mind the risks of cutting and possible discharge of hazardous materials when cutting synthetic materials.The available synthetic materials are thermoplastics, thermosetting materials and synthetic rubber.

Organic compounds:

There is a risk of ignition in all organic cutting (nitrogen as the processing gas, or compressed air as the processing gas).Wood, leather, cardboard and paper can be cut with a laser and the cutting edges will burn (brown).

3) equipment purchase

CNC cutting machine:

It is composed of three parts, that is, the working table (usually the precision machine tool), the beam transmission system (sometimes called the external light path, that is, the beam transmission optical and mechanical components in the whole optical path before the laser beam reaches the workpiece) and the microcomputer numerical control system.According to the way the cutting cabinet moves relative to the worktable, it can be divided into the following three types:

(1) in the process of cutting, the beam of light (shot by the cutting torch) and the working table move. Generally, the beam moves along the Y direction and the working table moves in the X direction.

(2) in the cutting process, only the light beam (cutting torch) moves, and the table does not move.

(3) in the cutting process, only the workbench moves, while the beam (cutting torch) is fixed.

Five-axis machine

In industrial production, the problem of cutting three-dimensional components is sometimes encountered, and the general two axis, three axis laser cutting machine can only cut two-dimensional plane workpiece, which requires a cutting machine equipped with a manipulator, namely, five axis machine.

Laser punching and cutting machine

Before cutting the workpiece, the feasibility of laser cutting and the possible problems in the cutting process should be considered in advance.For example, can such materials be laser cut?What is the difficulty in cutting it?Is it necessary to conduct a trial cut on the sample?How to achieve the quality and precision of cutting?Where is the reference starting point for cutting the workpiece?And so on.

There are many factors that affect the quality of laser cutting. One of the important advantages of laser cutting is that it can control the height of the main factors in the process, so that the cutting workpiece can fully meet the customer's requirements, and the repeatability is very good.These main factors consist of cutting speed, focus position, auxiliary gas pressure, laser output power and other process parameters.

In addition to the above four of the most important variables that may affect the cutting quality factors include beam parameters (mode and the power, polarization of the laser beam, laser beam focus, pulse beam) and workpiece properties (material surface reflectivity, surface state), and the cutting torch and nozzle, other factors such as light path system, workpiece is fixed.

With the development of metal processing industry, the advantage of metal laser cutting machine is becoming more and more obvious, and its proportion is becoming larger and larger.

4) USES of laser cutting machine

There are a lot of materials that can be cut, laser cutting machine can be used for cutting acrylic, wood, cloth, leather, metal, etc., according to the size of the power format can be used in different industries.Cloth cutting can be used in clothing, carpet, industrial fabrics and other aspects, acrylic cutting machine can be used in acrylic crafts production and other aspects, wood cutting can be used as model making, metal cutting can replace the original cutting to do all kinds of metal products.The laser

5) light path compensation measures

(1) beam collimation is carried out by beam expander

The beam waist diameter is inversely proportional to the far field divergence Angle, and the larger the beam waist diameter is, the smaller the far field divergence Angle is.At present, beam extenders are mainly divided into two types: refraction and reflection, whose principle is equivalent to an inverted eyeglass.The main function is to reduce the far field divergence Angle by increasing the beam waist diameter, thus improving the instability of focus size and focus depth caused by the change of light path length. Currently, there are few studies on beam collimation in China, most of which are for the refraction type, and few studies on the reflection type.It is easy to design, process and adjust the refringent beam extender. However, because the temperature rise of the lens is easy to cause the distortion of the lens, the refringent beam extender is only suitable for the collimation of the light beam of the low-power laser.For high-power beam collimation like laser cutting machine, reflective beam expander is usually used.However, it is difficult to determine the curvature radius of the mirror surface of the reflector beam extender by analytical method, and it can only be obtained by numerical fitting method. Therefore, it is very difficult to design, manufacture and adjust it.For this reason, the optical path compensation of the flight optical path system of the laser cutting machine by means of beam collimating by beam expanding mirror has little effect.

(2) variable radius of curvature lens (VRM)

By adjusting the output flow of the variable pump to change the water pressure in the water tank inside the VRM lens, the radius of curvature of the focusing lens can be changed, thus changing the parameter f in the focusing equation.The variable curvature radius lens can dynamically adjust the beam's characteristic parameters when the optical path length changes, so as to maintain the stability of focus radius and focus depth.The VRM system is complicated in structure, high in cost and requires closed loop control.However, the domestic existing technology level, difficult to achieve the expected use effect.

(3) isoptical-path system driven directly by servo motor

Compared with the above two optical path compensation measures, isoptical-path has the advantages of simple structure, low cost, convenient adjustment, etc., which can ensure the spot area on the focusing lens remains unchanged in the continuous processing.At the same time, it can also change the radius and depth of focus when cutting according to different cutting process requirements.At present, the domestic research on optical path aspects also few, such as Yang Sheldon is of tianjin institute of urban construction, etc., the optical path length compensation system was put forward three kinds of organization design, and from the Angle of institutional analysis and comparison, the method of laser cutting machine in the design of the flight path of a certain guiding significance.Using the mechanism to realize the optical path compensation will make the structure size of the equipment too large, and at the same time increase the complexity of the equipment, so it is difficult to install and adjust.With the increasing maturity of servo control technology, it is an economical and practical optical path compensation scheme to directly drive the optical path device by servo motor, which has the advantages of simple structure and convenient adjustment.The compensation scheme of isoptric path directly driven by servo motor mainly includes laser generator, reflector fixed on the fuselage, compensating reflector on the motion device driven by servo motor, reflector on the beam and reflector on z-axis.When the cutting head fixed on the z axis moves in the direction of x and y, the compensating mirror moves in the direction of S to compensate for the change of optical path length, so as to keep the focus radius and focus depth unchanged during the continuous cutting process of the laser cutting machine.When there are different processing need, such as cutting stainless steel sheet and mild steel plate, need the focus of the different size, focal depth, walking speed, at this point, can be changed by the controller device such as a light path of the initial position to change the length of light path, and then change the lens surface beam diameter, ultimately change focus size and depth of focus, in order to satisfy different processing.

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