[0001] The present invention concerns a pair of grippers conveying the weft into the shed
of a loom.
[0002] It is known that one of the most delicate steps in the working of gripper looms is
the exchange of the weft yarn between the carrying gripper (which grips the yarn from
the weft presenting device at one end of the loom and carries it to the center of
the shed) and the drawing gripper (which draws the weft yarn from the carrying gripper
and conveys it to the end of the loom opposite to the feeding end). In fact, when
weft exchange takes place, it is either possible for the weft yarn to be missed -
if the drawing gripper fails to grip it, or the carrying gripper drops it - or for
it to get torn or broken, due to the shearing effect produced by the grippers when
crossing each other, with consequent loss of yarn or irreparable damage thereto.
[0003] Attempts have thus been made by constructors to improve, with the most disparate
means, the operation of weft yarn exchange between the grippers in a gripper loom.
[0004] This problem is also faced by the present invention, which supplies a fully new and
original solution thereof, by providing a pair of grippers of the type having gripper
bodies whose base is fixedly conected to the straps causing the motion thereof, characterized
in that the bodies of the two grippers are outwardly inclined in respect of the plane
perpendicular to the sliding surface of the bases of said bodies and of said straps.
[0005] The invention is now described in further detail, with reference to the accompanying
drawing, which shows a preferred embodiment thereof and in which:
Fig. 1 is a bottom view of the two grippers of the pair of weft grippers according
to the invention, substantially aligned and as they mutually approach;
Fig. 2 is a similar top view of the pair of grippers of fig. 1; and
Fig. 3 is a section view, on an enlarged scale, along the line III of Fig. 2.
[0006] With reference to the drawing, the two grippers 1 and 2, according to the invention,
are shown inside the shed of a loom in a substantially aligned position of mutual
approach, just before weft yarn exchange. They are moved, in known manner, by straps
3 and 4 guided in the loom (of which, part of the sley C and of the reed P can be
seen in fig. 3), also in known manner, by hook guide elements 5 and 6.
[0007] The drawing shows the weft yarn f to be conveyed through the shed, coming from the
loom feeding means (not shown) and with its free leading end 7, cut in the previous
cycle. The yarn f is retained in 8 into the carrying gripper 1 by a lever 9 fulcrumed
onto the gripper body and pressed by a spring against an elastic plate 10. On account
of the motion of the gripper 1, the yarn f is stretched between the retention point
8 and a guiding point 11 of the warp guard 12 of the gripper 1. In correspondence
of point 11 is released the reaction pull T to the force of inertia between the gripper
and the weft feeding means.
[0008] As weft yarn exchange takes place, the front hook part 13 of the drawing gripper
2 moves to the side of the front part of the gripper 1 retaining the yarn f and penetrates
between the same and the warp guard 12; at the same time, the length of weft yarn
f stretched between points 8 and 11 has to move beyond the surface 13A of the hook
13 of the gripper 2 in order to penetrate into the retaining wedge 14 thereof.
[0009] Once inserted into the wedge 14, the yarn f is efficiently retained in 15 in the
drawing gripper which, after having reversed its motion, can thus convey it to the
end of the loom opposite to the weft feeding end.
[0010] In order to give the yarn full possibilities to bend during exchange, and to prevent
the two grippers 1 and 2 - when crossing each other and producing a shearing effect
- from causing tears or damage to the yarn, the invention provides to form a certain
angle α between the retention surfaces of the two grippers. For this purpose, both
bodies of the grippers 1 and 2 are formed outwardly inclined to an equal extent (fig.
3) in respect of the plane N perpendicular to the sliding surface 0 of the bases 1A
and 2A thereof and of the straps 3 and 4 onto the sley.
[0011] This solution (clearly illustrated in fig. 3 of the drawing) allows to obtain, according
to the invention, a distance between the yarn retention points 8 and 15 in the two
grippers 1 and 2 which is almost equal to the distance between the retention point
15 in the drawing gripper 2 and the guiding point 11 on the warp guard of the carrying
gripper 1, onto which is released the tension of the yarn; this allows to make the
best use of the elastic characteristics of the weft.
1) Pair of weft grippers for looms, of the type having gripper bodies whose base is
fixedly connected to the straps causing the motion thereof, characterized in that
the bodies of the two grippers are outwardly inclined in respect of the plane perpendicular
to the sliding surface of the bases of said bodies and of said straps.
2) Pair of weft grippers as in claim 1), wherein the bodies of the two grippers have
the same inclination in respect of said plane.
