JPS6229537B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a weft insertion device with a gripper bar which can be advanced and retracted into a woven fabric in a shuttleless loom.

Usually, in this type of loom, a tube is provided, into which the gripper bar is introduced during its retracting movement. This tube not only prevents the risk of injury to the worker, but also protects the gripper bar.

As a matter of practice, the rear part of the gripper bar in the tube has hitherto run freely or rest on a running surface arranged as a string in the tube. The guide of the gripper bar is provided exclusively, on the one hand, by a drive pinion which engages in the rack of the gripper bar in the drive mechanism and, on the other hand, by a guide roller opposite this pinion, either before or after said drive. This is done by means of lateral guide rollers. These lateral guide rollers are supported by sliding members arranged against the gripper head, which sliding members are guided along the fabric inside the shed.

During rapid actuation, the rear part of the gripper bar, which is freely arranged in the tube, ends up oscillating in all directions, which oscillation is in the best case limited to one direction by the aforementioned running surface. This tendency to oscillate can be reduced to a slight extent due to the complicated adjustment of the running surface.
Although it can be reduced, this tendency cannot be eliminated. This oscillation leads to wear of the guide elements and gripper bars. Furthermore, failures can occur when transferring the weft yarn from the weft transfer gripper to the weft receiving gripper in the center of the shed. This is because the gripper bar is oscillated periodically. Such a failure not only results in an uncertain weft thread transfer, but also, under certain circumstances, results in damage to the gripper itself or to the thread.

The object of the present invention is to eliminate these drawbacks and to provide a precise weft delivery in a shuttleless loom of the type mentioned at the outset, with an essentially reduced tendency to oscillation by an improvement in the guidance of the grip bars. The goal is to ensure that According to the present invention, the above-mentioned problem is solved by disposing a guide surface in sliding contact with the wall surface of the tube at the rear end of the gripper bar. Preferably, the guide surface consists of a cylindrical ring carried by a radial support, but it can also be constructed from an assembly of several components.
The through holes between these radial supports create an air flow inside the tube during operation. Furthermore, under certain circumstances, it is possible to utilize the air flow generated by the piston action and to extract this air flow, for example from the open rear end of the tube. If necessary, the guide surface can also be designed as a piston.

This method of guiding the trailing end of the gripper bar in an enveloping tube makes it possible to substantially improve the guidance of the entire gripper bar without harmful oscillations, which results in a reliable positioning in the center of the fabric. Thread delivery is guaranteed. One of the above-mentioned side guide rollers that were conventionally required can be omitted;
The guidance is improved to such an extent that a simpler drive/guide block structure than heretofore possible on the outside of the tube is possible. It is easy to integrate the gripper bar with guide surfaces or guide pistons straight into the interior of the tube, and because of the above-mentioned lack of a special running surface arranged inside, the tube itself is simple and inexpensive, and this offers further price advantages.

Embodiments of the present invention will be described below with reference to the drawings.

First, the structure of the apparatus will be briefly explained with reference to FIGS. 1 and 2. At its front end, the gripper bar 2 carries a gripper head 3 with a clamping device for thread transfer. The structure of the gripper bar 2 itself will not be described in detail. The grip bar 2 has a toothed part, also not shown, which engages a drive pinion 4 for the advancement and retraction of the grip bar 2. The gripper bar 2 is provided with a pinion 4 on the side surface of the bar 2 by means of this pinion 4 and a roller 5 disposed opposite to this pinion.
It is guided by a guide roller 6 arranged in front of. A further lateral guide roller 6' arranged behind the drive pinion 4 is shown in dotted lines. This guide roller can be omitted due to the advantages provided by the invention. The gripper head 3 rests against the fabric 8 by means of guide elements and is guided there in the usual manner. In the retracted position, the gripper bar 2 runs protected into the tube 1. At the rear end of the gripper bar 2 there is arranged a guide member 7, for example a ring, which corresponds to the cross-section of said tube and slides along the tube. The rear end of tube 1 is open.

FIG. 3 shows the guide surface 7 seen from the rear end of the tube 1. A cross section of the gripper bar 2 is shown by dashed lines. The connection between the guide surface 7 and the gripper bar 2 by means of a screw 12 is clearly visible in FIG.
This figure also shows the drive rack structure of the gripper bar 2 in longitudinal section. The guide surface 7 essentially consists of a cylindrical ring 9, which is covered, for example, with a slidable coating layer 11. By means of this coating layer, it is easy to set a certain play between the guide surface and the inner surface of the tube wall. In this embodiment, the guide ring 9 is carried by radial supports 10 and is connected to the gripper bar 2 via these supports 10.
A connection is established. The spaces between these supports 10 allow air flow from one interior of the tube 1 to the other during the forward/backward movement of the gripper bar 2. Such air flow aids in cooling during operation.

Optionally, the guide surface 7 can also be designed as a closing plate with an annular flange edge or as a piston, which can optionally be used for air supply, but this will not be discussed further. Don't explain. As mentioned above, the advantage of the invention lies in the inventive improved guidance of the gripper bar, in which case disturbing oscillations are avoided and accurate thread feeding is ensured. The effective guiding baseline corresponds to the entire length of the gripper bar from the sliding member of the gripper head against the fabric to the guide surface at the trailing end of the gripper bar. In between these points, as in the prior art, a gripper bar drive/guide block is arranged with a drive pinion and guide rollers, one of which can be missing as described above.

[Brief explanation of the drawing]

Figure 1 is a plan view of the gripper bar, Figure 2 is the top view of the gripper bar.
3 is a side view, FIG. 3 is an end view of a guide ring provided on the gripper bar, and FIG. 4 is a sectional view of FIG. 3. DESCRIPTION OF SYMBOLS 1...Pipe, 2...Gripper bar, 3...Gripper head, 4...Drive pinion, 5, 6'...Guide roller, 7...Guide surface, 8...Woven fabric, 9...Ring, 10... Supporting member, 11...Covering layer.

Claims (1)

[Scope of Claims] 1. A gripper bar having a toothed portion; a drive pinion that engages with the toothed portion of the gripper bar to advance and retract the gripper bar into the shed;
A weft insertion device equipped with a gripper bar in a shuttleless loom, which has a guide member provided at the rear end of the gripper bar, and a tube that slides on the guide member and guides the gripper bar in the front and back direction. 2. Weft insertion device with gripper bar in a shuttleless loom according to claim 1, characterized in that the guide member has a cylindrical ring supported by a radial support. 3. A weft insertion device equipped with a gripper bar in a shuttleless loom according to claim 1 or 2, wherein the guide member is covered with a sliding member.