INFLUENCE OF DEFOCUS POSITION ON LASER CUTTING PROCESS IN SHEET STEEL

Some researches about influence of defocus position to carry out laser cutting technological process through melting when producing lamellae for electric motors are presented here. Experimental series at defocus position Δf in the range – 3, 5 mm to + 3, 5 mm with two grade electrical steels M250-35A and M530-50A are described, too. The experiments are performed with a technological laser system TruLaser 1030. Functional dependencies of cutting width from defocus position b = b (Δf) have been shown. Theoretical relationships connected to the change of impact on a unit of area working spot over power density qs of the laser radiation and interaction time tproz (respectively cutting speed v), are examined to

STUDY OF AUXILIARY GAS PRESSURE ON LASER CUTTING TECHNOLOGY

Two types of electrical sheet steel M250-35A and M530-50A were used to cut by melting with a TruLaser 1030 technological system. It was observed that pressure of auxiliary gas had a major effect on kerf width b and cut angle deviation α. Nitrogen as an assisted gas has been taken. The basic parameters as laser power, cutting speed, focus position were constantly supported and the pressure was changed from 4 bar to 20 bar by step 2 bar. As well as the experimental results of gas pressure on entrance and exit kerf widths, have been analyzed and discussed in this study

LASER AS A DEVICE FOR MEASUREMENT OF THIN THREADS - A SCHOOL LABORATORY EXPERIMENT IN PHYSICS

The physics of the last century is included in all EU curricula and emphasis in education is shifted from content to the forms, methods and means of teaching and learning. Different kinds of lessons (including laboratory classes) and their didactic structure are subject to the understanding, adoption and creating conditions to build motivation to learn physics and astronomy, active utilization of physical knowledge and building cognitive and practical skills. Performance of demonstration and laboratory classes using a laser device is a type of teaching strategy to good education in physics. Properties of laser light as observation, classification, communication, drawing conclusions, planning, interpretation and forecasting, are particularly suitable when monitoring and studying the phenomena of interference and diffraction. Through both qualitative and quantitate ways, in this paper is presented a physical experiment for measurement of thin threads in a High school from students. Experimental skills will enhance interest in physics and especially to modern applications of laser devices, as well as career guidance of students

COMSOL SIMULATION OF LASER WELDING OF ALUMINUM

This research includes a Comsol Mutiphysics model describing the temperature distribution on aluminum during the laser conductivity welding process. The influence of  laser power and speed on the welding process is discussed and compared with experiments. Numerical simulations of laser welding process have been performed to determine the temperature fields of laser impact to samples of aluminum. Numerical calculations are made for fiber laser. The plots of the temperature dependence on the surface and in the depth of aluminum samples on the velocity are analyzed for several power densities for this laser.

METHODOLOGY FOR AUTOMATIC DETERMINATION OF CONTRAST OF LASER MARKING FOR DIFFERENT MATERIALS

A new methodology for determining and optimizing the contrast of the technological laser marking process has been developed. It can evaluate the quality of the markings regardless of the type of material and the type of laser system. To perform the test analysis, a specialized test field is programmed, which including the change of two of the main parameters influencing the marking process: the linear energy density (LED) and the linear density of the pulses (LDI). Marking of a test field consisting of squares of a certain size is done by means of a raster marking method with a constant step between the lines. The results are processed with a digital camera and specialized software. The maximum blackening is compared with the background of all fields and is juxtaposed with the effective energy needed to obtain a certain contrast. Several consecutive iterations are made, with each of the following experiments excluding the variants with least contrast. Thus, the study consistently brings the result to a minimum working area of the basic technological parameters, providing the user's desired contrast of the marking. The developed author's method of automatically determining the contrast of the laser marking reduces the time for preliminary experimental research and gives a reliable and subjectively absent way of qualitatively marking different types of industrial products

PRELIMINARY NUMERICAL ANALYSIS FOR THE ROLE OF SPEED ONTO LASER TECHNOLOGICAL PROCESSES

Studying the impact of speed on a number of laser processes such as marking, engraving, cutting, welding and others is crucial for the optimization of these technological processes. The processing speed, along with the frequency of laser pulses and their duration, also determines the time of action in the processing area and hence the absorbed quantity of electromagnetic energy. Based on numerical experiments with specialized software TEMPERATURFELD3D, the report analyzes the temperature variation in the processing area as a function of speed. The researches were analyzed for processing with two types of lasers emitting in the visible and infrared areas of the electromagnetic spectrum and two types of steels (tool and structural). From the course of the obtained temperature fields the dependence of temperature on the speed at two power densities was obtained. The obtained results help to make a preliminary assessment the speed work intervals for the processes as laser marking, laser engraving, laser cutting, laser welding and others. In this way, it is assisted in building an optimal concept for the passing of a particular technological process in function of the laser source, the material and the type of the technological operation

LYOPHILIZED HIKING FOOD DEVELOPMENT TRENDS

The consumption of functional food is increasing in almost all industrialized countries, not only because of an aging population, but also because of a more enthusiastic lifestyle, which makes meeting the nutritional requirements more difficult. In part, the transition to processed, easily packaged and pre-cooked foods is considered to be a response to long working hours. It resulted in an increased demand for ready-to-eat foods in recent years and it is expected to continue growing. The aim of the research is to study and analyze lyophilized hiking food development trends.  Methods used in the research – monographic, synthesis, statistical analysis methods. The research developed proposals for food processing companies for further development of lyophilized food

COLOR MARKING OF STAINLESS STEEL AND TITANIUM WITH THE LASER OXIDATION METHOD

Marking of metal products is essential in many industrial processes. It is mandatory for the finished products according to regulations of the European and world legislation. Traditional marking usually creates contrasting symbols that can easily be erased and forged.In recent years, a new method for product identification has appeared - color marking. One of the advantages of this method is that it is difficult to counterfeit. This article aims to present the progress of color marking technology on two types of materials. Three groups of factors have been analyzed: the laser source; the technological process; material properties. Their role in obtaining a specific color marking on Ti and AISI 304 is shown. The results are presented in tables. Each color can be repeated only with strict observance of the three groups of factors.

ON-LINE PROFESSIONAL TRAINING FOR WORKERS WITH THE MOODLE SYSTEM TO IMPROVE PROFESSIONAL SKILLS IN GREEN CONSTRUCTIONS

On the global agenda, environmental issues are becoming ever more pressing every moment. At present, it is not enough for individual countries to tackle global climate issues on their own. The time has come for a joint effort to mitigate climate change. The Paris Agreement is an agreement within the United Nations Framework Convention on Climate Change, dealing with greenhouse-gas-emissions mitigation, adaptation, and finance, starting in the year 2020. The Paris Agreement's long-term goal is to keep the increase in global average temperature to well below 2 °C above pre-industrial levels, and to limit the increase to 1.5 °C, since this would substantially reduce the risks and effects of climate change. It is not enough for states to sign this type of act, they need to take active steps to implement them and achieve the set goals. Energy, green construction, resource saving, educating the population, new and advanced teaching methods - all that is required for any global setup to be locally addressed. Now, we are in a situation where the exchange of transnational experience and knowledge is an important stage in solving energy efficiency issues through the education prism. This article will provide an analysis of the experience of four countries in the field of green construction. 

LABORATORY EXERCISE TO DETERMINE CONTRAST IN LASER MARKING OF ARTICLES

The laser marking has been established in recent years as one of the modern innovative methods for marking many industrial products. The report examines a new laboratory exercise for the subject Laser Technology, studied in some technical universities. A new approach is proposed to determine the contrast of the laser marking process. Described is the purpose and the main tasks as well as the new skills and knowledge that students can exercise through this laboratory exercise. Students implement a test matrix consisting of squares of a certain size using the raster marking method. Through the new laboratory exercise, students can explore and analyze the dependencies of the contrast of laser markings on different dimensions influencing the technological process. The capabilities of the new approach allow learners to become more familiar with the factors that influence the modern process of laser marking widely used in modern industry. The results of the experiments the students summarize using a new modern digital approach to analyze the contrast against the background of the marked surface. From the experimental graphical dependencies of the variation of the power and speed contrast, they draw conclusions about the optimal process parameters.