Failure analysis of the tensioner of the hottest h

Failure analysis of tension wheel of hand-held strapping machine (Part 1)

[Abstract]: tension wheel in hand-held strapping machine is the key part of strapping work under the comprehensive action of various alternating forces. Through the testing and analysis of the material composition, metallographic structure, hardness and worn surface morphology of tension wheels made of different materials at home and abroad, it is shown that the service life of tension wheels made of 20CrNiMo steel in foreign countries is longer than that of domestic products, and they are more suitable for application in hand-held strapping machines

handheld strapping machine is widely used in product packaging process by more and more industries, including metallurgical industry. At present, in steel mills, smelters and other enterprises, hand-held strapping machines are used to pack metal materials of various specifications, such as pipes, bars, plates, coils and non-ferrous metal billets. The tensioning wheel is the key component of the hand-held strapping machine. Its function is to tighten the steel belt for packaging in an instant and bind the metal products. The service conditions are mainly to bear the effects of pressure, friction, impact and other alternating forces, and its quality directly affects the service life of the whole machine

in this paper, the process tests of domestic and imported tension wheels were carried out on the production site, and the comparative analysis and research were made from the aspects of material selection, metallographic structure, worn surface morphology and so on

1 test method

two k-19a hand-held strapping machines were used in the small material workshop of a steel plant, and three groups of domestic tensioning wheels I and imported tensioning wheels II were installed respectively. Main technical parameters of strapping machine: traction force ≥ 2600n, the demander will pay attention to roughness when selecting this kind of equipment; The latter uses the servo system to observe its quality. The number of revolutions of the tensioning wheel is ≥ 50R/min; Binding completion time ≤ 8s. The width and thickness of steel strip for packaging is 19mm × 0.6mm conforms to gb4173 standard. yes Φ 40 seamless steel pipe for packaging, and the outer diameter of the bundled finished product is ≥ Φ 500mm。 Conduct the test according to the test specification until the tensioner fails, and list the service life in Table 1

it can be seen from table 1 that the average service life of the tensioning wheel of prototype I is 18700 times, and the average service life of the tensioning wheel of prototype II is 61100 times. The service life of imported tension wheels is more than 3 times that of domestic tension wheels

2 test results and analysis

2.1 material

the material analysis of domestic and imported tensioning wheels was carried out on the Swiss ARL spectrometer. The main chemical components measured are shown in Table 2

it can be seen from table 2 that the material of domestic tensioning wheel is GCr15 chromium bearing steel, and the material of imported tensioning wheel is 20CrNiMo carburized steel

2.2 hardness

the hardness test of domestic tensioner is carried out on hr-150 Rockwell hardness tester. Test results: the hardness of the first sample at three points is 60.5, 60 and 61hrc respectively; The second sample is 60.5, 61.5, 61hrc; The third sample is 59, 60 and 60HRC. The mean value is 60.4hrc

the pressure in the oil cylinder is also increasing. The hardness test of the imported tensioner is carried out with hxd-1000 microhardness tester. Test a point every 0.05mm from the surface to the heart, the measuring force is 200g, and the holding time is 1.5s. The measured hardness gradient values are shown in Table 3

it can be seen from table 3 that the surface hardness tested at the outermost point of the surface layer is 593hv, which is the hardness value of the surface infiltration layer. The hardness tested at points 8 and 9 is 386hv, indicating that this is the hardness value of the non permeable layer