Návrh napájení pro stejnosměrné a střídavé elektromotory

The article deals with measuring system by Steiger Mohilo. The unit serves for measuring rotations of low power electric motors without contact specially intended for laboratories. There is available to measure AC motors and also DC motors using mostly in white appliances. The contribution also deals with finding suitable power supplies for these motors and their continual regulation provided on our markets.Tento článek se zabývá měřením systémem Steiger Mohilo. Přístroj slouží k měření rotace nízkoenergetických motorů bez potřeby speciálních laboratoří. Je vhodný pro měření střídavých motorů a také stejnosměrných motorů používajících se většinou v bílých spotřebičích. Příspěvek se zabývá také hledáním vhodného zdroje pro tyto motory a jejich vzájemnou regulací, dostupnou na našich trzích

Study of surface roughness of machined polymer composite material

The aim of this paper is to evaluate the influence of selected cutting parameters (speed of rotation and feed rate) on the surface topography of drilled WPC material. Objective of the study is to establish dependence of the surface roughness of borehole walls (parameter —average maximum height) on the speed of rotation and feed rate of a drill bit. Technological parameters of experimental drilling were feed rate of 100–300 mm·min−1 and speed of rotation of 2000–6000 rpm.Web of Scienceart. no. 30351

DENTAL IMPLANT MATERIAL (POLYETHERETHERKETONE, TITANIUM AND ITS ALLOYS, ZIRCONIA)

The goal of this article is to inform the reader of three distinct types of biomedical materials applied in the production of dental implants, focusing on characteristics and categorizations of biomaterials based on: titanium (Ti + its alloys), commercially manufactured synthetic polymers (polyetheretherketone) and ceramic materials (zirconium dioxide). Considering the development and construction of implants, specific material requirements are named (mechanical properties), corrosion resistance, compatibility, morphology, etc. Each of these materials represents a specific group of biomedical materials and has a number of advantages. However, in relation to the differences in their nature (metal, plastic, ceramic base), it is necessary to approach the choice of material for dental implants with respect to the specific implant design and the patient's health limitations

Polymer Concrete Composite – Preparation of Testing Samples

Presented article is focused on manufacture of composite materials based on polymer concrete mixtures. Article describes the very essence of polymer concrete as well as the properties of its individual possible components. In the second part, the paper deals with specific materials, machines and utilities, which are used in the manufacture of composite. The third part of the article describes the manufacturing process itself and the individual stages of production. Conclusion includes the acquired knowledge of the production as well as other possible improvements of the process

Possibilities of Carrying out Quality Control of Solder Joints Using the Burst test in the Practice

Nowadays, the human is surrounded by numerous things from small simple parts to sophisticated cars, ships, gigantic constructions. More sophisticated parts are composed of simple parts and there are various joining technologies of materials used either by way of dismountable or mountable joints. One of the possibilities of joining various parts together is soldering. High-quality joint is possible to ensure by carrying out quality control. This article is focused on the issue of carrying out quality control in soldering. The introductory part of the article describes the basic problems of the area of solder connections with consequent characteristic of non-destructive quality control - visual inspection. The second part of the article is focused on description of the Burst test of high-pressure oil cooler that was carried out in the practice. The final part of the article provides global evaluation of this test

Machining of Wood Plastic Composite Using AWJ Technology with Controlled Output Quality

The paper deals with the application of abrasive water-jet cutting to composite material containing natural reinforcement—wood plastic composite. The specimens were cut through the application of four flows of different abrasive mass: 150, 200, 250, and 300 g·min−1, respectively, and under different traverse speeds required to achieve the (expected) quality level Q1–Q5 (according to the SN 214001: 2010 standard). The output quality of Q1–Q5 was set in the CNC cutting programs and the real traverse speed values were calculated by machine control system according to change in the flow of the abrasive mass. The quality of surface topography was assessed using a tester (contact roughness) and an Inspectis digital zoom microscope. The results of topography–surface roughness parameters Ra presented here are compared with the values normalized for individual samples sets. The applied technology, i.e., the AWJ, eliminated the problem of tool wear and adhesion of the thermoplastic matrix to tool surfaces (compared to standard machining)

Quantifying the Mechanical Properties of Materials and the Process of Elastic-Plastic Deformation under External Stress on Material

The paper solves the problem of the nonexistence of a new method for calculation of dynamics of stress-deformation states of deformation tool-material systems including the construction of stress-strain diagrams. The presented solution focuses on explaining the mechanical behavior of materials after cutting by abrasive waterjet technology (AWJ), especially from the point of view of generated surface topography. AWJ is a flexible tool accurately responding to the mechanical resistance of the material according to the accurately determined shape and roughness of machined surfaces. From the surface topography, it is possible to resolve the transition from ideally elastic to quasi-elastic and plastic stress-strain states. For detecting the surface structure, an optical profilometer was used. Based on the analysis of experimental measurements and the results of analytical studies, a mathematical-physical model was created and an exact method of acquiring the equivalents of mechanical parameters from the topography of surfaces generated by abrasive waterjet cutting and external stress in general was determined. The results of the new approach to the construction of stress-strain diagrams are presented. The calculated values agreed very well with those obtained by a certified laboratory VÚHŽ