Experimental Research on Sheared Edge Formation in the Shear-Slitting of Grain-Oriented Electrical Steel Workpieces.

This study sought to experimentally develop guidelines for shaping 0.3-mm-thick cold-rolled grain-oriented ET 110-30LS steel using a shear-slitting operation. Coated and non-coated steel was used for the analysis. The coated sheet had a thin inorganic C-5 coating on both sides applied to the C-2 substrate. The first part of this paper presents an analysis of the quality of the cut surface depending on the adopted machining parameters, which were the control variables on the production lines. The second part presents an analysis of the magnetic parameters of the cut samples, which allowed for the specific impact of the quality of the cut edge on the selected magnetic features. Finally, an optimization task was developed to obtain a set of acceptable solutions on the plane of controllable process variables such as slitting speed and horizontal clearance. The obtained results can be used to control the shear-slitting process on production lines and obtain high-quality workpieces.

Finite Element Analysis and Experimental Investigation of Cut Surface Formation of Magnetic Silicon Steel in Shear Cutting.

Shear cutting allows for shaping materials with any length of cutting line with high efficiency and without negative thermal effects, but it causes stresses and deformations in the cutting zone of the material. This has a negative effect on the magnetic properties of the sheet in the areas of the cut edge. The main problem on production lines is to ensure appropriate control of the process so as to obtain the appropriate technological quality of the cut edge, free of not only defects in the form of burrs and shape deviations, but also the minimum deformed zone. This task is difficult due to the large number of control variables, the influence of which on the shaping of the material and the formation of the cut edge is not fully understood. The article attempts to determine the course of the cutting process and to examine the influence of control variables on the formation of the cut edge in the shear-slitting process in which the tools perform a rotary motion. For this purpose, FEM modeling, vision techniques and experimental studies were used. A 3D model of the process was developed, which enables a detailed analysis of the states of stresses, strains, displacements and fracture mechanisms of the material. The simulation results were verified using vision techniques, which were used in the work to observe the flow and cracking mechanisms of the material. Parametric analyses were performed for the process control variables. The research showed a significant influence of the cutting velocity and the clearance between the tools on the formation of the cut edge. The most homogeneous surface of the cut edge with the minimum burr height was obtained for the following parameters: rake angle α = 15-30°, horizontal clearance hc = 0.03 mm and slitting velocity v2 = 15 m/min. The developed results can be useful for controlling the cutting process on production lines in terms of maximum process efficiency while maintaining the appropriate technological quality of the cut edge.

Researches and Simulation of Elastic Recovery Phenomena during Roller Burnishing Process of Macro-Asperities of Surface.

The paper presents preliminary studies of a new innovative surface treatment method-the process of roller burnishing of macro-irregularities of the surface. As part of the work, the possibility of plastic shaping of the surface macrostructure with indentations (plateau structure), which will show anti-wear properties through appropriate surface shaping and the compressive stress state in the product's top layer, was investigated. The essence of the paper is the analysis of one of the aspects of the application of this processing method, i.e., the influence of the elastic recovery of the product on its technological quality measured by dimensional deviation. The main objective of the work is to develop adequate methods and mathematical models to enable the design of the macro-asperities of the surface burnishing process to maintain the dimensional tolerance of the shaped parts. The results of dependencies of elastic recovery of the asperities and the deviation of height, Δht, for sample depths of burnishing were presented. The model tests of the elastic recovery of the model material using the visioplasticity method show that with the increase of the value of the vertical surface asperities, the value of the elastic recovery of the material decreases. The increase of the deviation of the asperities' height causes a decrease in the value of elastic recovery. With the increase of the value of the vertical angle of the surface roughness, the value of the elastic recovery of the material is smaller.

[Assessment of worklife areas and stress intensity among Border Guard officers]. / Ocena obszarów zycia zawodowego funkcjonariuszy Strazy Granicznej a nasilenie stresu.

BACKGROUND: Stress is associated with the performance of high-risk occupations. It can be defined as a set of reactions that results from mismatched working conditions and requirements to capabilities of an employee. People who differently assess these areas of work may experience varying degrees of stress. MATERIAL AND METHODS: The total of 128 Border Guard officers took part in the test. A subjective assessment of areas of work was made by using the Areas of Worklife Survey. The Perceived Stress Scale (PSS-10) was used to examine the severity of stress. RESULTS: Three groups of examined people, differing significantly in the assessment of all areas of working life, were identified. Affiliation of the examined people to these groups explains 8% of the variability in the severity of stress. The results of the regression analysis allowed to consider the assessments of 3 areas of working life (control, rewards and workload) as important predicators of the severity of stress experienced by officers. The model turned out to be statistically significant, the variables included in the model explain 19% of the variability of the dependent variable. CONCLUSIONS: The officers who assess the areas of working life differently, differ in terms of severity of the experienced stress. The severity of stress is significantly related to the ability to make independent decisions and to enjoy rewards. The stress experienced by Border Guard officers is mainly related to the assessment of the following areas of work: sense of control, rewards and workload. Med Pr 2018;69(2):199-210.