Papers by Nikola Vorkapic
Tehnika, 2021
U radu je prikazano konfigurisanje virtuelnog prototipa BiSCARA robota generisanog na osnovu komp... more U radu je prikazano konfigurisanje virtuelnog prototipa BiSCARA robota generisanog na osnovu kompletno razvijenog kinematičkog modela robota. Ovako razvijeni virtuelni CAD model će omogućiti njegovu implementaciju u Python grafičko okruženje kao integralnog dela sistema upravljanja otvorene arhitekture razvijenog na osnovu prikazanog kinematičkog modela. Razvijeni kinematički model je obu hvatio rešavanje inverznog i direktnog kinematičkog problema, određivanje Jakobijan matrice i analizu radnog prostora. Verifikacija kinematičkog modela, odnosno konfigurisanog virtuelnog prototipa ro bota, je izvršena simulacijama kretanja vrha end-efektora prema zadatom programu u CAD/CAM okruženju.
Advanced technologies and materials, Oct 1, 2020
In this study, 8011A aluminum alloy was subjected to artificial ageing and joined by tungsten ine... more In this study, 8011A aluminum alloy was subjected to artificial ageing and joined by tungsten inert gas (TIG) welding process. The effect of welding process on the mechanical (hardness, tensile, impact) properties, corrosion resistance and microstructure of the artificially aged and welded joints were investigated. The sample was divided into pre weld heat treated and as received samples. The pre weld heat treated sample was subjected to solution treatment at 500 °C, soaking for 1 hour, and quench in water before artificial ageing was carried out at 180 °C with holding time of 8 hours. Both the pre heat treated and the as received samples were welded using tungsten inert gas (TIG) welding process. It was observed from the results, that the pre weld heat treatment adopted improved the mechanical properties and corrosion resistance of the weldments in some of the properties examined. In comparison with the welded samples, the hardness, tensile yield strength and corrosion resistance of the pre weld heat treated samples were significantly improved. There was an improvement of 11% in hardness, 9% in yield strength and 92 % in corrosion resistance when immersed in 3.5 wt% NaCl solution.
FME Transactions, 2019
Presented research is focused on CNC milling operations of planar contours with flat end mills. P... more Presented research is focused on CNC milling operations of planar contours with flat end mills. Paper presents a set of functions requred for processing the workpiece model and NC part program in order to reconstruction the instantneous area of workpiece engaged by the tool. A Z-map interpretation of workpiece was chosen. Reconstructed engagement map, with previously obtained specific cutting forces, is enough for prediction of instantaneous and representative milling forces in points of programmed toolpath. Further, in order to maintain a specified level of milling force, the correction of the feedrate in toolpath points and then rediscretization of the path is enabled. Paper presents an example of experimental identification of speciffic cutting forces and the results of applications of the procedures, developed in Matlab, for optimization of feedrates. Results obtained through experiments are used for discussion of advantages and limitations of applied models.
FME Transactions, 2022
This paper presents an approach for developing the programming and offline simulation systems for... more This paper presents an approach for developing the programming and offline simulation systems for low-cost industrial robots in the MatLab/Simulink environment. The approach is presented in the example of a virtual model of a 4-axis robot with hybrid kinematics intended for manipulation tasks. The industrial robot with hybrid kinematics consists of the well-known 5R planar parallel mechanism to which two serial axes have been added. The programming system developed in a MatLab environment involves generating G-code programs based on given pick and place points. The virtual model included in the simulation system is configured in the Simulink environment based on the CAD model of the robot and its kinematic structure. The kinematic model and the inverse kinematic problem have to be included in the virtual model to realize the motion of the virtual robot. The system of programming and simulation has been verified through several examples that include object manipulation to perform various tasks.
FME Transactions, 2021
This paper describes configuring the virtual horizontal machining center LOLA HBG80 within the pr... more This paper describes configuring the virtual horizontal machining center LOLA HBG80 within the programming and verification system and the open architecture control system. The horizontal machining center LOLA HBG 80 is represented by an equivalent virtual machine in a CAD/CAM environment (PTC Creo and Catia), STEP-NC Machine environment, and the control system. Virtual simulation is essential for machining, and the developed virtual machines are used for program verification and monitoring of the machining process. The virtual machine in the programming system allows the verification of the program before sending it to the real machine and includes verification of the tool path (CLF-Cutter Location File) and G-code. The paper also discusses the possibility of applying a new programming method known as STEP-NC and preparing an adequate environment that includes a virtual machine. The virtual machine in the control system represents the last level for the final program verification a...
FME Transactions, 2020
This study was carried out to investigate the antibacterial activity against pathogens of acne an... more This study was carried out to investigate the antibacterial activity against pathogens of acne and the antiinflammatory effect of 75% ethanol extract and its fractions from the leaves of Prunus sargentii. In the antibacterial activity by the disc diffusion assay, the extract showed the highest effect against Propionibacterium acnes, Staphylococcus aureus and Staphylococcus epidermidis in 5 ㎎/disc. However, the ethyl acetate fraction showed the highest antibacterial activity in 1 ㎎/ disc. On the other hand, the hexane and chloroform fraction showed strong nitric oxide (NO) production inhibitory effect in lipopolysaccharide (LPS)-stimulated Raw 264.7 cell. In the cell viability of Raw 264.7 by MTT assay, the extract and all fractions were exhibited normal viabilities as nontoxic result. Consequently, the extract from the leaves of P. sargentii and its ethyl acetate fraction could be applicable to functional materials for antibacterial activity related fields. Moreover, the hexane and chloroform fraction could be applicable to candidate materials as anti-inflammatory agent.
Tehnika, 2019
U radu je pokazano konfigurisanje sistema za programiranje i upravljanje jedne realizovane koncep... more U radu je pokazano konfigurisanje sistema za programiranje i upravljanje jedne realizovane koncepcije troosne mini CNC mašine alatke čije je upravljanje zasnovano na Raspberry Pi platformi koristeći Machinekit upravljački softver. Za potrebe verifikacije sistema programiranja konfigurisana je i virtuelna mini CNC mašina alatka, u sistemu za programiranje, u različitim pogodnim okruženjima. Verifikacija programiranja je ostvarena na konfigurisanoj virtuelnoj mašini koja radi na osnovu zadatog programa i iscrtava programiranu putanju alata. U radu je predstavljeno konfigurisanje i implementacija upravljanja na Raspberry Pi platformi za mini CNC mašinu alatku, čija je verifikacija realizovana probnim radom mini CNC mašine alatke.
Tehnika, 2020
The paper shows the development of a 3-axis CNC machine tool for rapid prototyping by subtracting... more The paper shows the development of a 3-axis CNC machine tool for rapid prototyping by subtracting materials, with two translational and one rotating axis, whose control is based on the LinuxCNC system, with an integrated virtual machine as a digital twin. The concepts of machines with one rotary axis were analyzed and the concept of a machine for realization was adopted, which is completely configured in a CAD/CAM environment. For successful verification of the programming system, a virtual machine has been configured in the CAD/CAM system, as well as in Vericut. The final validation of the machine design was achieved by its trial work on characteristic examples.
In this paper, a mini CNC machine tool with three translational axis and open–architecture contro... more In this paper, a mini CNC machine tool with three translational axis and open–architecture control system is being considered. Existing CAD/CAM software environment was used in order to create adequate corresponding virtual machine and to enable CNC program development and testing for the specific platform. Prototype of the machine was made utilizing parts salvaged from multiple CD/DVD drives. Control system hardware is realized in two ways: based on PC platform and based on Raspberry Pi 3B+, while the software part uses open– architecture LinuxCNC. Experiments were performed in order to verify proper functioning of the entire system.
FME Transactions, 2019
Presented research is focused on CNC milling operations of planar contours with flat end mills. P... more Presented research is focused on CNC milling operations of planar contours with flat end mills. Paper presents a set of functions requred for processing the workpiece model and NC part program in order to reconstruction the instantneous area of workpiece engaged by the tool. A Z-map interpretation of workpiece was chosen. Reconstructed engagement map, with previously obtained specific cutting forces, is enough for prediction of instantaneous and representative milling forces in points of programmed toolpath. Further, in order to maintain a specified level of milling force, the correction of the feedrate in toolpath points and then rediscretization of the path is enabled. Paper presents an example of experimental identification of speciffic cutting forces and the results of applications of the procedures, developed in Matlab, for optimization of feedrates. Results obtained through experiments are used for discussion of advantages and limitations of applied models.
Journal of Mechanical Science and Technology
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Papers by Nikola Vorkapic