Year: 1899

page_text: Date of Application, 2nd Aug., 1899-Accepted, 30th Sept.,
1899
A communication from FRIEDRICH AUGUST THOENES, of Radebeul, near Dresden,
in the Kingdom of Saxony.
:
I, ALFRED JULIUS BOULT, of 111, Hatton Garden, in the County of London, ...
Chartered Patent Agent, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement:
Packing rings stamped out of asbestos pulp or asbestos fabric have the dis-
advantage of being expensive in manufacture. If for instance circular or exter-
nally oval, and internally circular shaped packing rings are to be produced, the
disc-shaped waste pieces may, of course, up to a certain limit, be still employed
for making smaller packing rings, but square, oblong or angular rings with
rounded angles cut out of the material to form the individual rings necessitate
a considerable and unavoidable loss of material. Rings of asbestos pulp (with
which the present invention however has but little in common) are unable to
withstand a comparatively high pressure; whilst rings made of asbestos fabric
have the disadvantage, that by stamping such rings out of a texture of crossing
threads, these intersecting threads are cut through. The longest threads, in
packing rings of this kind, are those which reach the edges of the ring tan-
gentially, the greater number of the threads are however considerably shorter.
It is thus evident that the strength of the fabric is materially weakened.
To obtain a more advantageous manufacture and to avoid the defect inherent
in the stamped-out rings referred to, is the object of the present invention, the
essential feature of which is that a continuous asbestos thread or asbestos cord
is wound spirally with its windings touching each other, the individual windings
being united into a firmly cohering body by cementing or embedding in india-
rubber or equivalent. In this body all the threads (if the individual windings
may be thus described) are arranged circularly, and not radially or tangentially,
so as to be able to resist most efficiently the inner pressure. Each thread, or
winding, forms, as it were, a closed and independent packing ring. No inter-
mediate spaces or weak points that may be attacked by the steam or the like are
formed on the edges.
The rings produced according to the present invention from a continuous
length of thread are to be clearly distinguished from rings or discs made from
tubular structures, produced by winding layers of woven fabric and covering
them with indiarubber, and subsequently cut up into more or less thick discs
or rings. It is also true that flat rings have already been formed out of strips
of fabric by winding in such a manner, that an annularly returning cord com-
posed of spiral windings was produced. The article forming the present invention

page_text: differs from the latter kind inasmuch as it consists of a single continuous cord
wound spirally; the manufacture of symmetrical rings from strips of fabric is,
however, difficult, and the products frequently being of unequal thickness and
of different closeness or density at different places and in such cases they are
subject to unequal pressures between the flanges and readily allow leakage at
the weak places.
The rings obtained according to the present invention will usually be flat;
they may however some times be made conical or be otherwise shaped, if they
are to be applied to packing surfaces of a surrounding shape. The rings need
not always be circular or rounded. If two or more spiral layers of cord are
enclosed in a common india-rubber cover, or are cemented together, it does
not alter in any way the essential feature of the invention.
Figure 1 of the drawing represents a circular packing ring;
Figure 2 a rectangular (for instance one suitable for tightening the cover of a
slide valve box);
Figure 3 a cross section on a considerably enlarged scale.
Figures 1 and 2 clearly show the path, in which the asbestos cord or thread
is wound. The ends of the cord are preferably slightly tapered, so as not to.
project.
The cross section, Figure 3, shows the ring in a compressed condition. The
windings of the originally circular asbestos cord a have become elliptical owing
to the pressure. The asbestos cord of several asbestos threads (shown in white
in Figure 3) interwoven with two lead wires (shown in black in the same figure).
The whole is embedded in an india-rubber cover or coating b which also serves
to cement the individual winding a together. In the constructional form repre-
sented by the cross section, an india-rubber jacket is shown, which may under
certain circumstances be made still thicker. On the other hand, however, rings
may be made in which no india-rubber jacket is used, but in which the india-
rubber merely serves as the binding agent for the asbestos cords. As equivalents
for the india-rubber as the binding agent, jacket or cover, gutta percha and other
substitutes may be employed. The asbestos threads or cords may consist of pure
asbestos, or as already referred to, may contain metal threads (lead, copper or
brass wires). The asbestos may also, in cases where the resistance to heat is a
secondary consideration, be substituted by other fibres capable of being spun
and made up into threads or cords. In each case the threads or cords will be
more equal to their requirements, the more strongly they are twined.
For making the rings, a core presenting the shape and size of the required ring
opening is employed, which is secured upon a flat plate; the cord being then
wound around this core in windings upon the plate. A kind of spool or flanged
disc may also be employed, the reduced portion of which, between the flanges,
corresponds to the shape and thickness of the rings opening desired. The asbestos.
or other cord, prior to its winding is covered, or the wound spiral is soaked with
an india-rubber or like solution or is embedded in india-rubber. The ring thus
formed is then pressed and usually covered with plumbago in the manner usually
adopted in making packing materials.
Having now particularly described and ascertained the nature of the said
invention as communicated to me by foreign correspondent and in what manner
the same is to be performed, I declare that what I claim is :-
1. A packing ring consisting of a continuous thread or cord wound in the
form of a spiral with its windings arranged close together the said windings
being secured together by embedding them in or covering them with india-rubber
substantially as described.
2. The manufacture of packing rings of the kind described, consisting in wind-
ing a thread or cord upon a core corresponding in its shape and dimensions to
the inner shape and dimensions of the ring to be produced, the spiral winding
being continued upon said core until the size of the required outer diameter is

page_text: reached, the windings being cemented together, connected or covered prior to or
subsequent to the winding operation, with india-rubber or the like and the ring
being finally subjected to pressure, substantially as described.
L 1000
BOULT & WADE,
Agents for the Applicant.