Rollers for Roller Kilns
The transport of goods through a roller
kiln is facilitated by a roller track. The goods to be fired
stand on plates, and these are transported through the kiln
by the slowly rotating rollers.
The evenness and straightness of these rollers must be tightly-controlled,
since "crooked" rollers would result in uneven transport
velocities, disturbing the relative arrangement of plates
and eventually resulting in malfunctions.
It is clear that for rollers with a diameter of 40 mm and
a length of 2500 mm, the manufacturing tolerances achieved
nowadays are closer than the values quoted by DIN 40 680.
This is shown in Table 32, where present technical standards
are contrasted with DIN 40 680. According to DIN 40 680, it
is necessary to use the "coarse" precision level
according to Table 29 in order to determine the tolerances,
since the component has a diameter > 30 mm. The standard
tolerances quoted below are taken from Table 30 for dimensional
tolerances and Table 31 for shape tolerances.
Table 32: A comparison of
the tolerance values according to DIN 40 680 ("coarse")
with the usual manufacturing tolerances (unmachined) for a
transport roller with Ø = 40 mm and l = 2,500 mm