Applied Mechanics and Materials Vol. 616

Abstract: This paper deals with the evaluation of crystalline structure and thermal properties of injection molded parts based on polylactic acid (PLA) matrix reinforced by banana and hemp natural fibres (NF). Using differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD) methods were evaluated thermal properties and crystalline structure of PLA/NF composites, depending on the amount of natural fibres within the weight ratio of 10% up to 30%. We observed that hemp and banana fibres work like natural nucleating agents and thus subsequently improve the material properties of PLA. We also observed process of melt (primary) and cold (secondary) crystallization of PLA/NF composites depending on cooling rate.

Abstract: All components of a huge machine tool need to work together perfectly to ensure not only a quality finished product, but operator safety. One of those many components is the material of support panels and moving parts in the machine construction. Mechanical structure of the machine, in most cases does not reach the technical level of regulatory techniques or electric drives and potential increase in dynamics, speed or accuracy of the machines remain unused. Used classic construction materials, steel or light alloy then zoom in to limit their physical capabilities. Designers have machine tools or robots are forced to solve the formidable task in the form of reducing the weight of the moving parts while maintaining or even increasing stiffness with respect to the thermal stability or damping. Laminates are for construction of production machines, robots and manipulators of crucial importance. One big advantage is the high rigidity while maintaining low specific weight. The presented paper is focused on the investigation of composite sandwich construction produced by prepreg technology, which is the suitable production choose for construction of machine tools parts. First of all, the production of sandwich structures with cork core, honeycomb core and foam cores are compared and described. In terms of the production process it is a method very friendly to the environment, since there are no leaks styrene vapours into the air. Since it is important from the perspective of a manufacturer of transport or machine industry manufactured from environmentally friendly materials, so naturally from materials that are from the perspective of safety of passengers (operators of machine tools or robots) at a high level, when any accident was lowest possible hazard due to fire (burn materials used) and terms of the strength of composite materials. This is one of the major scientific articles and to find the most ideal surveyed composite sandwich materials that would be the greatest possible extent fulfils the required properties. In the experimental part of the article are compared and investigated the mechanical characteristics of composite sandwich structures with regard to varying number of layers of predimpregnated skin materials due to the different types of core materials suitable for use in the machine industry. In addition, these characteristics are an important part of the article research because described the influence number of layers to values of the bending stiffness those composite structures.

Abstract: Machining as a base technology for the manufacture of precision engineering components has a dominant position. Interaction of machine - tool - work piece has a significant impact on the quality of surface, next to under surface changes of worked material and finally to the total production process. In this work microstructures characteristics of the arising chip are evaluated depending on the defined conditions used for machining. Further basic patterns of the manufacturing process as well as the accompanying effects on the cutting process are clarified. Theory of formation of chip is not nearly closed part of the analytical theory of cutting indicates a possibility of further investigation boundaries of these zones of deformation, the application of mathematical, physical and other methods of examination, verification of modern experimental methods. Thickness of chip was achieved to 50 µm. This micro hardness value was selected to the plastic zones. In area of primary plastic deformation was in range from 256,7 to 264,0 HV 0,1. Area of secondary plastic deformation was higher as primary plastic deformation, it was in range of 289,4 to 357,4 HV 0,1. In plastic deformation area was in range from 261,5 to 278,2 HV 0,1 which is consequence of the action of the outgoing temperature

Abstract: A human being cannot imagine recent times without technology and digitalization as well as without constant using of computers, computer networks and developed programmes for design and testing assemblies used in various areas of human ́s life. The submitted paper deals with a principle of a stroke. Priority of it is a design of an ideal mechanism for movement of curling machine lower cylinder and creating an analysis to find out its strength during acting of pressure forces.