Laser cutting machine is used for processing plexiglass (acrylic), with high speed, high precision and accurate positioning. It can make craft gifts, panel mirror boxes, model toys, advertising light boxes, signboard displays, packaging boxes, etc.
① Good cutting effect: no fire throwing, very smooth, bright, no serration, can cut 20mm acrylic at one time.
② Excellent performance of the whole machine: it can work continuously for 24 hours. It is Taiwan original rail, accurate and durable.
③ Fast cutting: for example, it is used to Cut 3mm thick acrylic plate.
In the past 30 years, laser cutting and welding of thin metal plates have been used to locally heat the beam. This method is flexible and has high economic benefits, and has been widely used in many industrial fields. In fact, the thermal conductivity of glass is lower than that of metal, so laser should be naturally applied to glass cutting. In fact, some companies have been developing complete systems since the 1970s, when kilowatt level CO2 lasers were used. However, due to the high power, the thermal impact on the glass can not be ignored, and the local material melts. At that time, the laser cutting technology was difficult to ensure that the cutting edge was neat and smooth, and it was still necessary to grind the cutting edge in many applications. At the same time, CO2 laser was very expensive at that time.
Laser cutting of plexiglass
Laser induced separation
Recently, some engineers and scholars have found that glass can be separated by low-energy laser without thermal effect such as melting. The method language is complex and involves many details. Its basic principle is to "separate" the glass by using the stress caused by the laser. During this period, with the maturity and development of closed CO2 laser technology, laser cutting glass technology became more economical and practical.
In this study, a CO2 laser with an average output power of 150W (K-150 type of coherent company) is used to form an elliptical focal point on the glass surface through the focusing optical path to ensure that the laser energy is evenly distributed on both sides of the cutting line. After the glass absorbs the 10.6 micron laser, almost all the energy is absorbed by the 15 micron absorption layer on the glass surface, compared with the cut line formed on the glass surface by the laser. Select appropriate movement speed to ensure that there is enough laser heat to form local stress distribution (set cutting line) on the glass surface to prevent glass melting.
In the laser cutting process, the quenching gas (water) nozzle is a quenching gas (water) nozzle. With the movement of the laser spot, the quenching gas (water) nozzle blows the cold air (water) to the glass surface, breaking the cold air (water) in its maximum direction, thereby separating the glass along the set direction.
It should be pointed out that in order to cause glass fracture, first of all, small initial cracks should be cut at the starting point of the cutting line by mechanical means.
By selecting processing parameters such as laser power and spot scanning speed, the fracture depth caused by stress can reach 100 microns to several millimeters, that is, by using laser method, 100 microns to several millimeters of glass can be cut step by step.
Because this process depends on the thermodynamic stress, its fracture depth and cutting speed are closely related to the expansion coefficient of the material itself. Generally speaking, the expansion coefficient of glass suitable for laser cutting should be at least 3.2x10-6k-1. Fortunately, most ordinary glass can meet this requirement.
Acrylic laser cutting
Achievements and Applications
This new method has some remarkable advantages over the traditional mechanical cutting method. First, this process can be completed in one step, drying and processing. The edges are smooth and tidy, without subsequent cleaning and polishing. In addition, the laser-induced separation process produces high-strength, natural tempered edges without micro cracks. With this method, unpredictable cracks and residual cracks are avoided, the defective rate is reduced, and the output is increased.
Edge quality
The dynamic differences of three different cuts on 1.5mm thick glass flakes were qualitatively analyzed. The cutting edge is clean, without cracks, cracks and subsequent processing procedures. As the laser is a non-contact tool, there is no tool wear problem, so continuous and uniform cutting thickness and edge quality can be ensured. In contrast, 3 (b) shows the case of edge cutting with a metal wheel, and it can be seen that there are various residual tension components along the cutting line. 3 (c) is the result of diamond grinding wheel cutting. In many applications, many tiny cracks can be seen, and the edges need to be polished and cut.
In order to quantitatively evaluate the edge quality, the stylus profilometer shall be used to measure the laser cutting edge according to the requirements of iso3274. Official tests show that the average roughness (RA) is less than 0.5 microns.
Boundary strength
Due to good edge quality and natural tempering during heating / quenching, laser cutting edge strength is very high. Otto Schott Institut of Jena has conducted independent tests on din5230011 parameters, and relevant data have been published. With this method, the edging strength is increased by about 30% compared with the machined sample.
Thickness and cutting speed
There are 3 factors affecting the cutting speed: glass thickness, material thermal expansion coefficient (see Fig. 2) and laser output power. CO2 laser is used in this experiment, with output power of 150W, cutting a = 7.2x10-6, glass thickness of 1.1mm, linear cutting speed of 500mm / s. In contrast, glass of the same thickness can be cut with the same hard metal wheel at a speed of 1500 mm / s. However, even in speed focused applications, the economic and quality advantages of laser cutting can make up for this difference. We all believe that further optimizing the processing technology and adopting laser cutting with high output power can increase the processing speed by 2-3 times.
Bending cutting
Since the crack is a precise mark on the laser beam, the laser-induced separation can cut a very accurate curve pattern. In fact, our experiments have also proved that laser cutting can achieve continuous and accurate setting mode in the case of straight lines or curves, and the repeatability can reach + 50 μ m。 In this way, accurate cutting of curves and three-dimensional graphics can be realized.
apply.
Laser separation technology will replace mechanical methods in many glass cutting applications. In recent years, laser cutting has shown strong technical advantages in the following three application fields: CRTs, flat panel display, automobile windshield cutting, etc.
Some applications require special subsequent treatment of glass, for example, some safety glass elements need to undergo temperature hardening treatment, and most silicon coated flat panel display elements must undergo temperature annealing. This special post-processing method matches the laser-induced separation method. We cut 100 pieces of 4mm thick glass without damage during special heat treatment.