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Exemple:
1. Si la valeur obtenue est trop rapide ou trop lente, suivez les
instructions:
»
Vérifiez que la pression d'air entrant est conforme aux spécifications du
régulateur / filtre et ajustez si nécessaire.
»Avec un petit tournevis, réglez la vanne de régulation de vitesse de descente
de la table (Figure 7-5, pos. 13). Tourner la vanne dans le sens des
aiguilles d'une montre réduira la vitesse d'application de la charge.
Tourner la vanne dans le sens antihoraire augmentera la vitesse
d'application de la charge.
Détermination du temps de chauffage approprié
The location of the condensation zone in the molding sand test specimen
is influenced by the heating time selected by the user. The tensile
strength in the condensation zone is the weakest within the sand
specimen. The sand sample will typically experience a tensile failure
(rupture surface) in the wet layer.
To determine the proper heating time, carefully examine the break area
(rupture surface) of the sand specimen after completing a test. The sand
sample should fail with an even layer breaking through the wet layer.
The wet layer (rupture surface) should be at or just below the top edge of
the specimen tube and a complete solid plate of dry molding sand should
lift off and remain in the detachable ring of the specimen tube assembly.
If the rupture surface is uneven, then repeat the test with less or more
heating time.
Graphic 1 shows the effect of selecting different heating times on the
same molding sand sample. Position 2 would be considered the correct
heating time. Position 1 would be considered an excessive heating time
and Position 3 would be considered insufficient heating time. Typically,
the proper sand specimen heating time will result in the lowest wet
tensile strength
man-STC-42112-V17-3 French
.
Testeur de résistance à la traction humide
Maintenance et étalonnage 6
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