Naberezhnye Chelny, Kazan, Russian Federation
The study objective is to identify the causes of destructing angular elements of the transport trolley bracket of the sliding roof mechanism during their operation. The task to which the paper is devoted is to identify the effect of the method of obtaining a die cutting and laser cutting on the bending quality of angular elements at radii close to the thickness of the sheet and a bending angle of 90° relative to the upper surface of the bracket base. Research methods: visual and measuring control, profilographic analysis, spectral analysis, metallographic analysis, hardness and micro hardness measurements. The novelty of the work: the study of the effect of chipping and laser cutting of blanks from sheet metal on the occurrence of defects during their bending at a radius close to the thickness of the sheet and a bending angle close to 90. The study results: the surface roughness after laser cutting (Rz=8.032 microns in the blow area) is 3-4 times less than after chipping (Rz=21.34 microns in the rupture area). The depth of the thermal impact area after laser cutting is 0.17-0.23 mm. The thinning of the material at the bending point is 0.25 mm. The microhardness of the layer varies in depth from 170-204 HV15 up to the core which is 94 NV. The steel grade of the parts obtained by chipping is 20KP, while laser cutting is 08KP. Based on the analysis of applying various research methods, the negative effect of laser cutting is found out, which consists in the occurrence of defects after bending metal with a radius equal to the thickness of the sheet at a bending angle of 90. After bending the parts, which blanks are made by laser cutting, significant micro-cracks up to 0.7 mm deep are revealed and single microcracks with a depth of up to 0.15 mm are observed after chipping. Conclusions: the causes of breakdowns in the operation of the angular elements of the bracket are cold plastic deformation of the cast structure, lateral surface of the angular elements, at the bending point of the sheet and leading to microcracks, which are stress concentrators. It is not recommended to use laser cutting at the bending points along the edges of the workpiece.
sheet metal, cold bending, chipping, laser cutting, cracks, roughness, microstructure, hardness
1. Maltsev NR, Bikmukhametova MA, Zabaturin AM. Bending defects arising in the manufactureing of housing elements of oil refinery equipment. Izvestiya Tula State University. Technical Sciences. 2025;5:242-249.
2. Verkhov EYu, Morozov YuA. Analysis and development of technology for manufacturing bent thick-sheet parts. Bulletin of Moscow State Open University. Series: Engineering and Technology. 2011;4:14-19.
3. Tamila VA, Nesterovich ML. Research of high strength steels bending. Foundry Production and Metallurgy. 2020;3:71-78.
4. Tamila VA, Nesterovich ML. Bending technology of high-strength steel sheets and tools for its realization. Foundry Production and Metallurgy. 2020;1:50-55.
5. Astashchenko VI, Safarov DT, Shveeva TV, Sochenko TV. Features and experience of using high-strength steels for cold sheet stamping of automobile parts. Bulletin PNRPU. Mechanical Engineering, Materials Science. 2024;26(3):74-81.
6. OST 26.260.758-2003. Metal structures. General technical requirements. Moscow; 2003.
7. OST 1 00286-78. Bending radii of sheet materials made of steels. Moscow; 1978.
8. Chukin MV, Poletskov PP, Alekseev DYu. Study of the ability of high-strength steel to plastic deformation when bending at the angle of 90°. Journal of Siberian Federal University. Engineering and Technologies. 2016;9(8):1326-1332.
9. Morozov YuA, Verkhov EYu, Krutina EV, Frolov AA. Development of an evaluation technique for determining the plasticity resource in sheet bending processes. V Mire Nauchnikh Otkrytiy. 2015;12-3(72):882-896.
10. Astashchenko VI, Galimov ER, Shveev AI. Method for determining the suitability of steel for cold plastic deformation. RF Patent No. 2568887 C1 MPK G01N 33/20, G01N 3/40. 20 Nov 2015.
11. Feoktistov SI, Andrianov IK. Assessment of the upper and lower levels of permissible strains in the manufacture of sheet and thin-walled parts based on the forming limit diagram. Vestnik Tomskogo Gosudarstvennogo Universiteta. Matematika i Mekhanika. 2023;86:136-148.
12. Keller IE, Petukhov DS, Kazantsev AV, Trofimov VN. The limit diagram under hot sheet metal forming. A review of constitutive models of material, viscous failure criteria and standard tests. Journal of Samara State Technical University, Ser. Physical and Mathematical Sciences. 2018;22(3):447-486.
13. Vilimok YaA, Evdokimov AK. Comparative analysis of limi stampability under biaxial tension. Izvestiya Tula State University. Technical Sciences. 2014;7:71-75.
14. Kozlov ED, Botkin AV. Computer modeling of bending of the part "Staple" MolodezhnyjVestnik UGATU. 2024;1(30):60-65.
15. Klochkov VN, Podymako ME, Kolesov IA. Modeling of the technological process of bending sheet parts at the stage of designing stamping equipment. Vestnik of Brest State Technical University. 2024;2(134):98-103.
16. Nesterenko ES, Shcherbov MI. Simulation the bending process of a part with a bending angle greater than 90 degrees in an improved die with elastic elements. Izvestiya Tula State University. Technical Sciences. 2021;6:380-383.
17. Fedorina EV, Dyakov IF. Nomenclatural cluster of sheet stamping parts for designing metal cutting. Models, Systems, Networks in Economics, Technology, Nature and Society. 2018;1(25):203-219.
18. Fedorina EV, Kokorin VN. Process simulation of metal cutting order to minimize costs. Strengthening Technologies and Coatings. 2016;4:39-43.
19. Ambos E, Neubauer A, Oswald Yu. Economy of raw materials. Moscow: Metallurgiya; 1989.
20. Babaev FV. Optimal cutting of materials using a computer. Moscow: Mashinostroenie; 1982.
21. Minaev IV, Sergeev NN, Tikhonova IV. Method of forming a hardened near-surface layer in the area of laser cutting of parts. RF Patent No. 2695715 C1 25 Jul 2019.
