GB2034769A

GB2034769A - A Thread Gripper

Info

Publication number: GB2034769A
Application number: GB7937362A
Authority: GB
Original assignee: Adolph Saurer AG
Current assignee: Saurer AG
Priority date: 1978-11-15
Filing date: 1979-10-29
Publication date: 1980-06-11
Also published as: BE880046A; DE2936116C2; GB2034769B; IT1165231B; IT7968813A0; BR7907361A; DE2936116A1; CS209827B2; ATA838178A; CH633589A5; FR2441674A1; DE7925355U1; FR2441674B1; AT359444B

Abstract

A gripper for a weft inserter comprises a forked member 2 with rigid prongs 3, 7, a pad 5 of elastomeric material located in a recess 4 in the prong 3, and a tongue 6 which is pressed by the pad 5 against the internal face of the prong 7 to grip the thread 11 between the tongue 6 and prong 7, an abutment 9 to open the gripper is provided. <IMAGE>

Description

SPECIFICATION A Thread Gripper The invention relates to a gripper for textile threads in which a moving part is resiliently urged against a rigid part so as to hold a thread.

Grippers of this type generally comprise two parts which are usually made of metal and press against each other resiliently so as to secure the textile thread lying between them, owing to the friction force generated by the pressing force. The pressing force is generated by designing at least one of the parts either as a thin plate produced from spring steel, with one end clamped (rivetted, screwed, or fitted into a slot) under stress in a holder, or as a rigid lever which is pivotally hinged on a holder and is subjected to the action of a spring (usually a spiral spring), in which arrangement the opposing part can also be designed as a thin sprung plate or as a rigid member.

This type of thread gripper is relatively expensive to produce. Thread grippers having thin plates in the form of a leaf spring are also likely to break. Once the thin plates of the gripper have been actuated by the vibrations of the weaving loom or the picking needle, when they are being used as a yarn holder, they often tend to oscillate, so that the gripping force holding the thread tends toward zero at times.

An additional disadvantage lies in the fact that the contacting surfaces cannot adapt to the differences in the thickness of the textile thread, with the result that the contacting surfaces can be exposed to strong local pressures.

Moreover, the known thread grippers are relatively heavy, particularly the ones having a lever as their moving part, and are therefore disadvantageous if used, for example, in a weft thread picking needle (high inertia, and high pressure on the warp threads of the under-shed or on the guide elements of the picking needle).

What is desired is a light thread gripper which can be produced from simple, readily exchangeable components, and the moving part or parts of which can be moved or pivoted in all directions.

The present invention provides a thread gripper which comprises a fork-like member with two prongs, of which one prong forms the rigid part while the other prong bears a pad of resiliently deformable material on its internal face, and the moving part is formed by a tongue which is guided on one of the prongs with clearance all round and is urged against the internal face of this prong by the pad.

For the sake of simplicity, the pad can merely be inserted in a recess in the supporting prong so that it can be replaced or exchanged if it is defective or if the resilience or deformability is to be adapted to the force required for pressing or holding the thread. Rubber or a rubber-like synthetic material are preferably used as the pad material.

In order to guide the tongue, the tongue is preferably provided with an elongate prismatic lug which passes through a correspondingly shaped guide opening in one of the prongs and projects beyond the external surface thereof. This lug can be used to exert force on the tongue from outside so as to remove the pressing contact of the tongue against the prong and to release the thread. This is particularly advantageous when using the thread gripper in a weft thread picking device.

In order to allow the tongue to pivot as much as possible so as to distribute uniformly the force pressing on the thread clamped between the tongue and internal surface of one of the prongs, the area of contact between the tongue and pad should preferably be restricted to a strip which is as narrow as possible, round the plane of symmetry of the tongue load. This can be effected by corresponding shaping of either the pad or the tongue or both parts. In terms of production, corresponding design of the tongue is more desirable. For this purpose the tongue may have a trapezium-like cross-section with two equal sloping sides and with its short base facing the pad.

The invention is described in more detail below by way of example with reference to the accompanying schematic drawings, in which: Figure 1 is a longitudinal section through a thread gripper along the line I-I in Figure 2; and Figure 2 is a cross-section through the thread gripper along the line Il-Il in Figure 1.

The drawings show the rod 1 of a weft picking device, on which is fixed a fork-like gripping member 2 with a prong 3 and prong 7. The prong 3 has a rectangular recess 4 into which is inserted a pad 5 of resiliently deformable material such as rubber or a rubber-like synthetic material. The pad 5 almost fills the internal clearance in height from the prong 3 to the second prong 7 and presses a tongue 6 (lying on the pad 5) against the internal face of the second prong 7. The tongue 6 has a trapezoidal cross-section with equal oblique sides and its narrow side lies on the pad 5. The prong 7 is provided with a rectangular opening 8 surrounding an elongate prismatic lug 9 of the tongue 6 with clearance on all sides. The lug 9 projects beyond the external surface 10 of the prong 7 when the tongue 6 is positioned against the internal face of the prong 7.

Figure 2 shows a thread 11 which is gripped between the tongue 6 and the internal face of the prong 7. To facilitate insertion of this thread 11, the tip of the prong 7 and the tip of the tongue 6 are rounded off, forming a funnel-shaped inlet 12.

In order to allow insertion and release of the thread, a temporary force is exerted on the lug 9 from outside against the pressure of the pad 5 so that the tongue 6 comes away from the internal surface of the prong 7, freeing a path for inserting and removing the thread 11.

A similar procedure is adopted for removing the tongue 6 or the pad 5 when it needs replacing: the force is increased until the lug 9 has been driven right out of the opening 8. It is then easy to remove firstly the tongue 6 and subsequently the pad 5 from the space between the prongs 3 and 7.

Claims

1. A thread gripper for textile threads, comprising a fork-shaped member with two prongs, a first one of which bears a pad of resiliently deformable material, and a movable tongue which is located on the second prong with clearance all round and is urged against the second prong by the pad, in order to grip a thread between the tongue and the second prong.

2. A thread gripper as claimed in claim 1, in which the pad is inserted in a recess in the first prong.

3. A thread gripper as claimed in claim 1 or 2, in which the pad is of rubber or a rubber-like synthetic material.

4. A thread gripper as claimed in any of claims 1 to 3, in which the tongue has a lug which passes through matching guide opening in one of the prongs and projects beyond its external surface 10.

5. A thread gripper as claimed in any of claims 1 to 4, in which the tongue has in cross-section the shape of a trapezium with two equal sloping sides whose short base faces the pad.

6. A thread gripper substantially as described with reference to, and as shown in, the accompanying drawings.

7. A weaving loom including a thread gripper according to any preceding claim.