EP0065231B1

EP0065231B1 - Arrangement for controlling the movement of the weft conveying grippers in shuttleless looms

Info

Publication number: EP0065231B1
Application number: EP82103943A
Authority: EP
Inventors: Nello Pezzoli
Original assignee: Vamatex SpA
Current assignee: Vamatex SpA
Priority date: 1981-05-15
Filing date: 1982-05-06
Publication date: 1986-03-05
Also published as: JPS584848A; EP0065231A1; CS228926B2; ATE18444T1; MX157727A; ES512116A0; DD202463A5; PT74898B; ES8305439A1; BR8202813A; IT1135816B; PT74898A; DE3269574D1; IT8121738A0; JPH0375653B2

Abstract

In a shuttleless loom, the movement of the weft conveying grippers is controlled by straps (2) moved backwards and forwards by gearwheels (1) mounted at the loom shed ends, the peripheral teeth of said gearwheels meshing with longitudinally aligned slots (3) provided at the centre of the straps. The engagement between the straps and the gearwheeis is constant and precise over a wide arc of the wheels, thanks to guides extending over the whole of said arc and acting on the lateral portions of the straps, and it takes place between elongated slots in the straps and correspondingly shaped teeth, with round-edged periphery, of the gearwheels.

Description

The invention relates to an arrangement for controlling the movement of the weft conveying gripper in shuttleless looms, of the type using a pair of gearwheels which perform short reciprocating rotations at the loom shed ends, and a pair of gripper advancement straps having longitudinally aligned central slots meshing with the teeth of said gearwheels.
An arrangement for controlling the movement of the weft conveying grippers is disclosed in the DE-B 29 02 729. In this arrangement the straps are however only guided tangential to the gearwheel, the guide cannot influence the strap in the vicinity of the wheel.
Further, the DE-B 20 20 765 discloses an arrangement, in which the strap having longitudinally extending slots positioned at close distance is laid around a wheel without special guide for the strap.
It is an object qf the invention to provide an arrangement of the mentioned type, in which the precision of the meshing between the gearwheel and the slots in the straps is ensured.
According to the invention this object is solved in that the arrangement comprises continuous fixed guides extending over a wide arc of the gearwheels along the periphery thereof and acting on both lateral portions of the outside surface only of the respective strap whereby the latter is held in constant and precise engagement with said gearwheels along said arc.
The invention is described in detail hereinafter with reference to a preferred embodiment thereof illustrated by way of example in the accompanying drawings, in which:

Figure 1 is an external view of the arrangement according to the invention, in correspondence of one of the gearwheels;
Figure 2 is a cross-section on the line II-II of Figure 1, showing the engagement between the gearwheels and the straps of the arrangement of Figure 1, and the action of the fixed guides associated to said gearwheels in ensuring continuity and accuracy of such engagement;
Figure 3 is a view of one of the gearwheels of the arrangement of Figure 1, showing the shape of its teeth;
Figure 4 shows a strap of said arrangement cooperating with the gearwheel of Figure 3; and
Figure 5 is a cross-section through the strap of Figure 4.

With reference to the drawings, the arrangement according to the invention comprises, on each side of a loom, a gearwheel 1 controlling a strap 2, to impart on said strap and on the gripper carried thereby the to-and-fro movements which govern the insertion of the weft yarn into the loom shed.
The strap 2 comprises at its centre a row of elongated rectangular slots 3 which are clearly shown in Figures 4 and 5. Through such slots, the strap 2 meshes with the peripheral teeth 4 - of corresponding or complementary shape (see Figure 3) - of the gearwheel 1, over a wide arc of which it extends, said teeth being also distinguished by their round-edged periphery.
The arc of the gearwheel 1, over which the strap 2 extends, is defined by guides 5 which partly surround the wheel close thereto. As clearly shown in Figure 2 of the drawings, the guides 5 are U-shaped so as to act at 6 and 7 on the lateral strap portions to the side of the slots 3, and thereby ensure a continuous and reliable engagement into said slots of the base of the teeth 4, which substantially project from the periphery of the gearwheel 1.
Important advantages are obtained with the described arrangement for a correct transmission of the reciprocating motion to the weft conveying grippers in looms.
Firstly, the thorough engagement of the gearwheel teeth 4 into the strap slots 3 - made precise by the shape of the teeth and slots, and made continuous and accurate by the presence and configuration of the guides 5 - determines the mutual positioning between the strap and the gearwheels with a precision so far inconceivable, thereby allowing a particularly even distribution of the loads over the teeth and thus less wear, reduced temperatures and less noise.
In addition, the elongated rectangular shape of the strap slots 3 substantially reduces the bending stresses in the straps and facilitates their deformation when meshing with the gearwheels, with no harmful consequences as far as strength and wear. In practice, the straps bend with a greater continuity than those of conventional technique (which comprise much smaller and, in particular, less elongated slots).
Finally, the round-edged periphery of the gearwheel teeth 4 ensures a smooth engagement, with no impact or wear, between the gearwheels 1 and the straps 2.

Claims

1. An arrangement for controlling the movement of the weft conveying grippers in shuttleless looms, of the type using a pair of gearwheels (1) which perform short reciprocating rotations at the loom shed ends, and a pair of gripper advancement straps (2) having longitudinally aligned central slots (3) meshing with the teeth of said gearwheels (1), characterized in that it comprises continuous fixed guides (5) extending over a wide arc of the gearwheels (1) along the periphery thereof and acting on both lateral portions (6,7) of the outside surface only of the respective strap (2) whereby the latter is held in constant and precise engagement with said gearwheels (1) along said arc.

2. An arrangement as in claim 1, characterized in that the slots (3) in said straps (2) are of substantially elongated rectangular shape, extending longitudinally with regard to the straps (2), and the teeths (4) of said gearwheels (1) are of corresponding or complementary shape.

3. An arrangement as in claim 2, characterized in that said teeths (4) substantially project from said gearwheels (1) and have a round-edged periphery.