Note: Descriptions are shown in the official language in which they were submitted.
L353
This invention relates to a flexible stringer strip
for racket having a stringed hitting surface, especially ten-
nix rackets, and having sleeves for protection of the strings.
In conventional stringer strips for tennis rackets,
it is often very difficult, because of distances between the
protective sleeves in the prefabricated strips and because ox
a lack of very precise matching of said protective sleeves
with the Berlioz for the strings existing in the frame of
the tennis rackets, to insert the protective sleeves into the
Berlioz. The reason for this is, inter alias that, possibly
with the exception of the Berlioz in the center of the
racket, the Berlioz along the frame have different angles
with respect to a common reference axis since at the point of
the Berlioz, the direction of said Berlioz extends normal
or almost normal to an imaginary tangent line at the frame.
U.S. Patent No. 3,930,648, discloses a flexible
stringer strip ox the type initially mentioned. However, this
strip is provided with relatively thick supporting cushions or
pads between the individual sleeves for supporting the fasten-
in loops that are formed where strings are pulled through a
sleeve and returned back through an adjacent sleeve. Further-
more, this strip must be adapted to the arrangement of bore-
holes of the racket construction by making the distances
between adjacent sleeves, in the direction to the center and
to the head of the racket, larger at a varying degree than in
the remaining arched area of the edge. A particular stringer
strip of this type can only be utilized for a specific racket
and cannot be used for rackets having different distances
between holes. In addition, because of the above-mentioned
different angular pistons and the unavoidable tolerances of
the Berlioz, the assembly process is relatively difficult.
The present invention provides a stringer strip of
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the above-mentioned type or a method to circumvent -these dip-
ficultles by simple means so that, without any additional
energy or time requirements, the stringer strip with the
sleeves can be fastened more easily on the racket and manufac-
luring tolerances can easily be compensated for.
According to the present invention there is provided
a flexible stringer strip of hard elastic material for a
racket having stretched strings, the strip having string-pro-
tooting sleeves arranged at a definite distance apart and made
in one piece with the stringer strip, in which the stringer
strip in each portion of the stringer strip between -two
string-protecting sleeves exhibits at least one expansion port
lion such that under tensile loading of the stringer strip in
the direction of its longitudinal extent only or essentially
only the said expansion portion is able to expand.
In one embodiment of the present invention the
expansion portion forms at least one part of an expansion wave
which, seen from the narrow edges of the stringer strip runs
in the plane of the strip.
In another embodiment of the present invention the
expansion portion forms at least one part of an expansion wave
which runs perpendicularly to the plane of the strip. Desire
ably each expansion wave is formed by at least two adjacent
notches extending from the one narrow edge and directed
towards the opposite narrow edge with adjacent notches start-
in respectively at opposite narrow edges of the stringer
strip.
The present invention will be further illustrated by
the accompanying drawings which show, for purposes of thus-
traction only several embodiments in accordance with the pro-
sent invention and in which:-
Figure 1 shows a stringer strip with expansion waves
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31 3~3
extending in the plane of the strip;
Figure 2 is a side view of a stringer strip where
the expansion waves extend normal the plane of the strip; and
Figure 3 is a top view of the strip according to
Figure 2.
A stringer s-trip, for a Dennis racket or for other
rackets having a hitting surface spanned with sirings, has the
reference number 1, with the protecting sleeves 2 of said
racket being provided at a predetermined distance from one
another and projecting perpendicularly from -the plane of the
body of the s-trip, to which they are unnatural formed. In the
strip 1, made of a hard-elastic material, sections 3, in thy
form of expansion waves 4, are in each case provided between
two protecting sleeves 2 in order to compensate for variations
in the lengthwise direction of the strip.
The expansion waves 4, according to Figure 1 embody-
mint, when viewed from the direction of the narrow edges 5,6,
extend in the plane of the strip 1. Furthermore, Figure 1
shows three forms of planar expansion waves 4. In the left
representation, they are formed by at least two (and as shown,
at least three) alternatingly by positioned slots or notches 7
and 8 which extend laterally from the narrow edges 5 and 6
toward the opposite narrow edge 6 or 5, respectively. The
result is that, between each pair of a protective sleeves 2,
in the expansion section 3, an expansion wave 4 is produced.
By means of these expansion waves the distance 9 between each
pair of protective sleeves 2 can easily be varied and can be
adapted, without extensive expenditure, to the distances be-
tweet the Berlioz of a racket frame through which the
strings are pulled. The length of the expansion waves 4 in
Figure 1, relative to -the centerline M, can amount to half a
wavelength to several wavelengths . One wavelength
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is preferably between 1.5 and 10 mm, especially between 2.5
and 4 mm. The flexibility of the expansion waves 4 can be
adjusted or fixed by the dimensioning of the standing ridges
10 and/or edge arches 11 extending transversely to the strip
1.
In the center waves represented in Fig. 1, V-shaped
notches 12 are provided for forming the expansion waves 4. In
the case of the waves represented on the rotund side of
Figure 1, the center notch is formed as a V-notch 12 and the
outside notches 13 are half-V-shaped notches 13.
In the embodiment is shown in Figures 2 and 3, the
expansion waves 4 extend normal to the plane the body of the
strip 1, as shown particularly clearly in Figure 2 by the pro-
section of the waves above and below the centerline M. In
this case, the material may also be weakened, as shown by the
left and the center embodiment wherein the waves are thinner
than the adjoining sections of strip 1. This makes it posy
sidle that the wave peaks need not necessarily project over
the top and bottom surfaces 14 and 15 of the strip 1, as is
the case with the central section 3.
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