(57) An automobile exhaust silencer has a casing 1, a central perforated tube 6 and an
end piece 5 at one end. A similar end piece is welded to the other end when the silencer
has been packed. Vacuum producing apparatus 2 is brought into contact with the closed
end of the silencer casing, aperture 7 registering with the perforated tube 6, and
a similar sealing member 9 having an aperture 10 is brought into contact with the
open end of the silencer casing, thereby blocking off the other end of the perforated
tube 6.
A strand or roving consisting of a multitude, for example, two thousand continuous
glass fibres of diameter, for example, less than twenty microns, is fed between two
rollers, one of which is driven, in gun 4 where a further roller having a cutter cuts
the roving into discrete lengths. An air blast assists in projecting the discrete
lengths forwards, and they are sucked into the silencer casing by means of the vacuum
to which the other end is subjected.
It is found that the individual fibres of each discrete length separate from each
other in the silencer casing to form the desired fluffed-up wool-like consistency
in the casing. Furthermore, with this method it is possible to accurately meter the
quantity of material fed into each silencer.
As an alternative to the use of a vacuum, a jet of compressed air may be used to establish
the required air flow through the casing.
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