[0001] The present invention relates to improvements in the drawing grippers for weaving
looms of the type with continuous weft feed, and it concerns more precisely an improved
arrangement for mounting the oscillating needle of a drawing gripper.
[0002] Drawing grippers are already known, wherein the weft thread to be conveyed through
the shed is locked in said grippers, between a fixed claw - usually shaped with a
hook end - and a needle oscillating in respect of said claw, under the opposing actions
of spring means which cause the engagement thereof with said hook end for gripping
and retaining the weft, and of pressure means operated by a member of the loom for
releasing said weft. In these grippers the needle is pivoted - for its oscillation
in respect of the claw - by means of a pin hinge arranged about half way through the
needle length and subjected to wear, like any device of this type. After a prolonged
use of the gripper, it therefore easily happens that, as a result of said wear and
failing any possible recovery of the slacks determined by such wear, an adequately
precise coupling of the needle with the claw portion onto which it must tighten the
weft thread is no longer guaranteed. This determines the requirement to replace the
gripper even if, in every other respect, said gripper could still continue to be used
for a long time.
[0003] The present invention proposes to overcome this drawback, by supplying a drawing
gripper of the aforementioned type wherein the needle is mounted by an improved arrangement,
with possibility to recover the slacks deriving from wear of the hinge through which
the needle is pivoted on the claw.
[0004] The improved mounting arrangement according to the invention is characterized in
that, the fixed gripper claw comprises a hemispherical cavity in the needle pivoting
area, and the gripper needle correspondingly comprises a complementary hemispherical
protuberance, said protuberance and said cavity defining together a spherical hinge,
and in that said hinge is held together by the action of the same spring which causes
the engagement of the oscillating needle with the fixed claw.
[0005] Preferably, said spring is a leaf spring and its action has the effect of a compression
inmparted on the needle towards the claw by means of a screw, whose head bears on
said spring and whose care crosses the needle to screw into the claw.
[0006] The invention is now described in further detail, by mere way of example, with reference
to the accompanying drawing, which represents a preferred embodiment thereof and in
which:
Fig. 1 is an axonometric 'view of the drawing gripper comprising the needle mounting
device according to the invention;
Fig. 2 is a cross section view through the area of the mounting device of figure 1,
along a horizontal plane; and
Fig. 3 is a cross section view through the area of the mounting device of figure 1,
along a vertical plane.
[0007] With reference to the drawing, figure 1 illustrates a drawing gripper of the type
in which, to a fixed claw 1 ending into a hook 2 there is associated a needle 3 oscillating
in respect of 4. The end 5 of the needle 3 is normally held in engagement with the
hook 2 of the claw 1 by the action of a leaf spring 6, for gripping and retaining
the weft thread T, while said engagement can be removed, for releasing the thread
T, by imparting a pressure onto the other end 7 of the needle, suitably shaped as
a projecting are, causing the needle itself to oscillate in respect of 4 against the
action of the spring 6.
[0008] The invention concerns an improved arrangement for mount-: ing the needle 3 on the
claw 1. According to this arrangement, the' fixed gripper claw 1 comprises, in the
needle pivoting area 4, a hemispherical protuberance 8 with a cylindrical extension
8', while the needle 3 correspondingly comprises a hemispherical cavity 9, complementary
to the protuberance 8, and a hole 10 into which is housed the extension 8' of said
protuberance 8. The needle 3 is coupled with the claw 1 by mating the protuberance
8 of said claw with the cavity 9 of the needle, whereupon the two parts are fixedly
connected together by a screw 11, the head 12 of which engages the compression spring
6, and the core 13 of which is screwed into the claw 1 through the extension 8' of
the protuberance 8, said extension being housed with a wide slack into the hole 10
of the needle 3.
[0009] This arrangement allows to obtain a fully satisfactory hinge for mounting the needle
3, so that this latter may oscillate in respect of the fixed claw 1, not only when
the gripper is new, but also after wear between the hinge parts: in fact, such wear
creates no inconveniences, as the slacks which could modify the reciprocal positions
between the needle and the claw (and thus influence negati
- vely the gripping and retaining of the weft thread T between the hook 2 and the end
5 of the needle 3) are constantly and continuously - recovered, thanks to the special
design and to the way of working of the hinge.
1) Improved arrangement for mounting the needle oscillating in respect of the fixed
claw of a drawing gripper for weaving looms with continuous weft feed, characterized
in that, said fixed claw comprises a hemispherical protuberance in the needle pivoting
area, and said needle correspondingly comprises a complementary hemispherical cavity,
said protuberance and said cavity defining together a spherical hinge, and in that,
said hinge is held together by the action of the same spring which causes the engagement
of the oscillating needle with the fixed claw.
2) Mounting arrangement as in claim 1), wherein said spring is a leaf spring and its
action has the effect of a compression imparted on the needle towards the claw by
means of a screw, whose head bears on said spring and whose core crosses the needle
to screw into the claw.
