Method of brush seal tufting

Wire is wound from spool 10 onto drum 15 where a multiple strand rope is formed and gripped at multiple locations. The gripped rope is cut into individual bundles, one end of each bundle being bonded to join the wires of the bundle together. The tufts may then be used to form a brush seal.

TECHNICAL FIELD 
The invention relates to the manufacture of metallic brush seals and in 
particular to a method of forming individual tufts for the fabrication of 
the seal. 
BACKGROUND OF THE INVENTION 
Brush seals can be applied to a variety of jet engine applications. Uniform 
wire bristle density is an important determinant of proper seal 
manufacture. 
One method of manufacturing of brush seals uses tufts containing uniform 
numbers of small diameter wires. In forming these tufts it is important 
that the wires not be twisted in a bundle and that they be aligned 
properly preferably prior to cutting to length. The procedure should 
preferably be one with little waste of wire and no sensitivity to the 
length of the feed strand. There should be an inherent accurate control of 
the number of wires in each tuft. 
SUMMARY OF THE INVENTION 
A supply spool or spools containing the metal wire which is to be used for 
the tufts is rotatably mounted on a support. The end of the wire is 
secured to a winding drum which is rotated with the wire wound in a slot 
around the periphery of the drum, thereby forming a rope. The rotation of 
the drum is stopped after a predetermined number of turns, this 
corresponding to the number of strands in the rope. 
The metal wire thread from the supply spool is then cut while the rope 
continues to be gripped at a plurality of locations on the drum. This 
gripped rope is cut into sections of predetermined length forming the 
tufts. These tufts are bonded at one end for use in a brush seal. Repeated 
cutting of the remaining rope is accomplished to complete the fabrication 
of the selected number of tufts.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIG. 1 a spool 10 containing metallic wire 12 is rotatably 
mounted on a frame 14. This wire is typically of a diameter of 0.0028 
inches. 
One end of the wire is secured to a drum 15 which is thereafter rotated in 
the direction shown by arrow 16. Clamps 18 are cammed to open and close 
permitting the wire to fit within a slot, with the clamped then closing to 
retain the wire. A wire tensioner 20 is located between the spool and the 
drum to provide uniform tension in the wire as it is wound around the 
drum. 
As the drum 15 is rotated a rope is formed, typically between 250 and 300 
wires corresponding to a like number of rotations of the drum. The wire is 
cut between the supply spool and the winding drum and secured to the drum. 
A typical clamp located on the drum 15 is illustrated in FIG. 2. The clamp 
22 opens and closes over a peripherally located slot 24 to retain the rope 
therein while opening to admit the additional strands. Plural spools 10 
may be used leading to fewer rotations for the desired number of wires. 
The actual number of wires may be more or less than the typical number set 
forth above. 
The mandrel 26 of the winding drum is preferably relocated to a second, 
tuft cutting location. Shown in phantom in FIG. 3 is a spool 30 and a 
tensioner 32 indicating that it is possible to carry out both operations 
at the same location. 
Also shown in FIG. 3 are the original clamps 18 which were used to clamp 
the wire during winding around the drum. Additional clamps 38 are used 
during the cutting operation, since the relatively short tufts must be 
retained by a clamp until they are secured together. 
Taking advantage of a notch 40 located in the winding drum a bundle of the 
rope is gripped by a clamp 42. The jaws of this clamp are configured to 
maintain the desired cross section of the wire bundle. A cutter mechanism 
44 severs the bundle of wires 46. One end is retained in the groove while 
the other end is removed by the clamp in a path 48 to locate the severed 
ends of the bundle at a securing station 50. Here the ends of the wires 
are welded together by welding mechanism 52. Alternate forms of joining 
the wires together such as shrink tubing glue or wax could be used. 
An indexing clamp arrangement 54 advances the wire bundle one tuft length 
with the drum rotating accordingly. The earlier secured and welded tuft is 
then severed from the end of the bundle. 
The newly cut end is positioned at the securing station and the process is 
repeated until the entire wire bundle has been used. Typically the drum 
will be about 29 inches in diameter with the total of 60 clamps being 
used. Six to twelve of these clamps will be used and activated on the 
first fixture during the winding of the wire around the drum to form the 
rope. The remainder are required in the cutting of the tufts which with 
the described drum would be approximately 60 tufts each one and a half 
inches long. 
After being so formed these tufts are then used for the fabrication of a 
brush seal. This machine may be easily modified for cutting tufts of 
different lengths and of different numbers of wires per tuft.