à Òåõíîëîãî-ãóìàí³òàðíèé óí³âåðñèòåò ³ì. Êàçèìèðà Ïóëàâñüêîãî â Ðàäîì³, ²íñòèòóò ìàøèíîáóäóâàííÿ, Ðàäîì, Ïîëüùà á Òåõíîëîã³÷íèé óí³âåðñèòåò AEåøóâà, Ôàêóëüòåò ìàøèíîáóäóâàííÿ òà àåðîíàâòèêè, AEåøóâ, Ïîëüùà Íàâåäåíî ìåòîäèêè âèçíà÷åííÿ ãëèáèíè ïëàñòè÷íî äåôîðìîâàíîãî âåðõíüîãî øàðó ìàòåð³àëó ïðè îáêî÷óâàíí³ ðîëèêîì. Àíàë³òè÷íèé ìåòîä ðîçðîáëåíî íà îñíîâ³ òåî𳿠Ãåðöà-Áåëÿºâà. Ãëèáèíó òàêîãî øàðó îòðèìàíî ÿê ôóíêö³þ çóñèëëÿ îáêî÷óâàííÿ, ì³öíîñò³ ìàòåð³àëó ³ ãåîìåò𳿠ðîëèêà. Àíàë³òè÷íèé ðîçâ'ÿçîê ïåðåâ³ðåíî îðèã³íàëüíèì ìåòîäîì, ùî áàçóºòüñÿ íà âèì³ðþâàíí³ ëèöüîâîãî ïðîô³ëþ ê³ëåöü. Ðîçðîáëåíî ìàòåìàòè÷íó ìîäåëü òåîðåòè÷íîãî ðîçâ'ÿçêó ³ ïëàí åêñïåðèìåíò³â. ×èñåëüíå ìîäåëþâàííÿ ãëèáèíè ïëàñòè÷íî äåôîðìîâàíîãî øàðó âèêîíàíî ìåòîäîì ñê³í÷åííèõ åëåìåíò³â. Ðåçóëüòàòè, îòðèìàí³ àíàë³òè÷íèì ³ åêñïåðèìåíòàëüíèì ìåòîäàìè, ïîêàçóþòü ¿õ õîðîøó â³äïîâ³äí³ñòü.Êëþ÷îâ³ ñëîâà: ãëèáèíà äåôîðìîâàíîãî øàðó, ïëàñòè÷íà äåôîðìàö³ÿ, ñê³í÷åííîåëåìåíòíèé ìåòîä, îáêî÷óâàííÿ ðîëèêîì.Introduction. Many material forming technologies such as burnishing, thread rolling, spline rolling, knurling, and drawing lead to both the deformation of the surface layer of the material and changes in its properties. This phenomenon introduces compressive stresses into the surface layer increasing its surface hardness, and both static and fatigue strength [1,2]. Under the pressure of the rounded tool, deformation not only occurs in the plastic forming processes, but also in turning, milling, grinding [3] or even laser surface treatment [4]. The deformation of the surface layer occurs during deep drawing of the thin sheet metal, where the complex stress state caused by the rounded tools leads to the change in friction conditions and loss of stability of the sheet material undergoing plastic tension [5,6]. The scale of plastic deformation in the above processes is smaller than in roller burnishing, but it is always possible to observe a plastically deformable surface layer. Plastic deformations of the metal surface can occur under relatively small forces, i.e. during measurements or assembly [7][8][9]. Roller burnishing causes strain hardening of the material and introduces compressive stresses into the surface layer that increase the hardness [10] and strength of the surface layer of the material [11]. In order to obtain greater depths of the
In the paper, analysis of the curved profile measurement accuracy is described. Since there was no CAD model or other reference profile for the measured detail, the first step was to generate the reference contour of the cam using the technical drawing and tolerance requirements. The test campaign consisted of three experiments aimed at determining the effect of scanning velocity on the results of form deviation δ measurement, evaluation of deviation δ measurement uncertainty and the measurement repeatability. The scanning time was checked, too. The obtained results demonstrated feasibility of the chosen CMM and measurement strategy. It was found also that the measurement uncertainty did not depend on the scanning sampling step from 0.05 to 0.2 mm, and the true measurement time was for 30-40% longer than that expected from the nominal scanning velocity.
In this study, the effect of the addition of silicon carbide to alumina ceramics commonly used in cutting tool applications is addressed. Performance of Al2O3–SiC composite cutting inserts during the machining of hardened steels and ductile iron was compared to the results obtained for a cutting tool made out of 99 wt.% Al2O3, Al2O3–TiC, Al2O3–TiC–ZrO2, and Al2O3–TiN. In almost all tests, the composite with silicon carbide demonstrated better wear resistance, longer tool lifetime, and the ability to cut at higher speeds. The enhanced properties of cutting tools with SiC can be attributed to the morphology and dimensions of the inclusions in the matrix as well as to the strength of the interphase boundaries, small porosity, and lack of high inner stresses in the volume.
Fabrication of alumina–tungsten carbide nanocomposite was investigated. Characteristics of the densification and sintering were analyzed considering both the nano-size particle starting powders and the processing stages. Different heating rates were generated during densification and consolidation with a maximal load was applied only after a temperature of 1000 °C was reached. Due to the varying dominance of different physical processes affecting the grains, appropriate heating rates and pressure at different stages ensured that a structure with submicron grains was obtained. With directly applied alternating current, it was found that the proportion Al2O3 (50 wt.%)–WC provided the highest fracture toughness, and a sintering temperature above 1600 °C was found to be disadvantageous. High heating rates and a short sintering time enabled the process to be completed in 12 min, saving energy and time.
The paper presents the results of the investigations on the direction-dependent accuracy of the point identification during contact probe measurements with a coordinate measuring machine (CMM). Considering the contact point identified by an orthogonal to the surface probe movement, the transformation of coordinates was made in order to calculate the displacement of the measured point. As a result, the positioning accuracy was estimated in three axes. The experiments demonstrated a strong dependence of the displacement on the declination angle. Moreover, it was found that the directional surface texture which provided different roughness in perpendicular directions, had an impact on the positioning accuracy.
This paper is devoted to the sintering process of Al2O3–SiO2–ZrO2 ceramics. The studied method was electroconsolidation with directly applied electric current. This method provides substantial improvements to the mechanical properties of the sintered samples compared to the traditional sintering in the air. The research covered elemental and phase analysis of the samples, which revealed phase transition of high-alumina solid solutions into mullite and corundum. Zirconia was represented mainly by tetragonal phase, but monoclinic phase was present, too. Electroconsolidation enabled samples to reach a density of 3.0 g/cm3 at 1300 °С, while the sample prepared by traditional sintering method obtained it only at 1700 °С. For the composite Al2O3—20 wt.% SiO2—10 wt.% ZrO2 fabricated by electroconsolidation, it was demonstrated that fracture toughness was higher by 20–30%, and hardness was higher by 15–20% compared to that of samples sintered traditionally. Similarly, the samples fabricated by electroconsolidation exhibited elastic modulus E higher by 15–20%. The hypothesis was proposed that the difference in mechanical and physical properties could be attributed to the peculiarities of phase formation processes during electroconsolidation.
In the paper, an issue of CMM measurement strategy of the sleeves and pins designed for wear tests in the cycloidal drive. The measurement strategy was proposed, based on initial out-of-roundness measurement in scanning mode. Proposed approach ensured that the pin was measured along its entire 40 mm length with only small area of fixation ca. 5 mm left out, and all probing points for cylindricity deviation assessment were collected in one fixation. It was demonstrated that the cylindricity and roundness measurement results based on 8, 16 and 48 probing points provided sufficient data for further wear analysis. In some cases, the circles calculated from 4 points gave additional insights allowing to accept the part that otherwise might be possibly rejected.
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