Avaliação de desgaste mecânico em agulhas de lingueta aplicadas em tear circular
Knitted textile structures are widely used by mankind, and they are produced on machines with a mechanical sliding system. The needles fit into trick wall (thin grooves) and slide over them in an alternating motion so that loops can be formed. This system naturally causes friction and wear on the...
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| Formato: | Dissertação |
| Idioma: | pt_BR |
| Publicado em: |
Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/handle/123456789/47661 |
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| Resumo: | Knitted textile structures are widely used by mankind, and they are
produced on machines with a mechanical sliding system. The needles fit into trick
wall (thin grooves) and slide over them in an alternating motion so that loops can
be formed. This system naturally causes friction and wear on the needles and trick
wall, which makes it necessary to replace these parts over time. This research
consists of an evaluation of wear on latch needles, in order to contribute to a better
understanding of the wear mechanism that occurs in this system. In order to analyze
the abrasion on the needle butt, a mechanical adaptation was made in a machine
that simulates abrasion on fabrics, so that a tribological pair was formed between
the needle butt and a cam, of the same model used in circular knitting machines.
To analyze the abrasion on the needle stem, a small diameter circular knitting
machine was used, with needles placed in random trick walls, analyzing the
abrasion from the contact between the tribological pair needle stem and trick wall.
For both cases, needles were separated and subjected to the following tests:
15,000, 30,000, 45,000, and 60,000 dry cycles, with Silvertex 32B oil lubrication (for
circular knitting machines) and with Silvertex 32B oil lubrication + metal conditioner,
at a single speed of 260 cycles per minute. The temperature was monitored with a
thermocouple fixed near to the friction zone. The samples were analyzed by
portable digital microscope image, Scanning Electron Microscopy (SEM) and
Energy Dispersive X-ray Spectroscopy (EDS). As a result, it was possible to verify
the points of the needle most susceptible to abrasion. It was found that internal
clearances in the trick wall influence the wear regions of the needle stem and that
deformities in the trick wall influence the wear intensity of the needle butt. The
temperature increment is higher in cycles without lubrication. So the lubricant
attenuate the temperature increase and the metal conditioner act as abrasion reducer. |
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