GB2111542A - A shuttleless loom having a gripper rod - Google Patents

Abstract

In a shuttleless loom (Fig. 1) which includes a weft thread insertion device having a gripper rod (2), the rod reciprocates into and from a protective tube (1). Within the tube troublesome vibration of the free, rear end of the gripper rod can occur and this vibration can be transmitted forwards to the gripper head (3) where it may prevent proper transfer of the weft thread. To prevent such vibration, a guide element (7) is arranged at the rear end of the rod (2), which element (7) slides back and forth inside the tube (1), for example in the manner of a piston. <IMAGE>

Description

SPECIFICATION A shuttleless loom having a gripper rod This invention relates to a shuttleless loom including a weft thread insertion device with gripper rods which are moved forwards and backwards in the shed of the loom. In such a loom it is usual to provide a tube at each side of the loom, to receive the relevant gripper rod on its backwards stroke. This tube not only protects the operator against injury but provides protection for the gripper rod.

The rear part of the gripper rod, situated inside the tube, has hitherto been free or arranged to lie on a ridge in the plane of movement of the rod in the tube. The rod has been guided entirely by a driving pinion of driving mechanism meshing with teeth on the rod and, at the other end, a guide roller situated opposite the pinion and by lateral guide rollers situated ahead of or behind the driving location and assisted by a sliding member arranged on the gripper head and guided along the reed within the shed.

During the rapid movements which occur in use of such gripper rods, the free near part of a rod inside the tube is subject to vibration in various directions and which at best can only be limited in one direction by the plane of movement mentioned above. This tendency to vibration may be reduced but not eliminated by a difficult adjustment of the plane of movement. The vibration not only leads to wear of the guide elements and of the gripper rod but may result in faults in the transfer of weft thread from the giving to the receiving gripper in the middle of the shed since the rod is activated to perform periodic vibrations. These faults not only result in unreliable transfer of the weft thread but may result in damage to the gripper itself or to the threads.

An object of the invention is to obviate or at least reduce these disadvantages in a shuttleless loom of the type mentioned above and substantially to reduce the tendency to vibration by improved guiding of a gripper rod so that correct transfer of weft thread may be ensured.

According to this invention, there is provided a shuttleless loom including a weft thread insertion device with a gripper rod movable back and forth in the shed, the rod moving within a tube in the rear part of its path of movement, wherein a guide element is in slidable contact with the wall of the tube and is disposed at the rear end of the rod. The guide element is preferably a cylindrical ring carried by radial supports, but it may alternatively be composed of several separate parts. The gaps between the several radial supports enable air to flow inside the tube during movement. It is also possible to make use of the air stream produced by the piston action and, for example, to remove this air stream at the rear end of the tube. If necessary, the guide element may be a piston.

Guiding of the rear end of the gripper rod in the enclosing tube substantially improves guiding of the rod without harmful vibration, thereby ensuring correct transfer of the thread in the middle of the shed. Guiding of the rod can be improved to such an extent that it becomes possible to dispense with one of the lateral guide rollers mentioned above, which had previously been required, and the driving and guiding unit outside the tube may be of simplified construction. Each gripper rod with its guide element can readily be placed straight in the tube, and the tube itself, owing to the elimination of the above mentioned special plane or track of movement inside it, may be made simpler and less expensive.

An embodiment of the invention will now be described by way of example with reference to the drawings, in which: Fig. 1 is a schematic top plan view of a gripper rod; Fig. 2 is a side view of Fig. 1; Fig. 3 is a section through a guide ring on the gripper rod; and Fig. 4 is an axial section through Fig. 3.

The construction of the embodiment will first be briefly described with reference to Figs. 1 and 2. A gripper rod 2 carries at its front end a gripper head 3 with a clamping device for transferring the weft thread. The construction of the rod 2 is not shown in detail. The rod 2 contains a toothed portion (also not shown) which meshes with a driving pinion 4 to move the rod 2 forwards and backwards into and out of the shed of the loom.

The rod 2 is guided by the pinion 4 and by a roller 5 situated opposite the pinon 4 and by a guide roller 6 arranged laterally of the rod 2 and in front of the driving pinion. Another lateral guide roller 6' behind the driving pinion 4 is indicated in broken lines, since it may be omitted by virtue of the advantage achieved by the invention. The gripper head 3 makes contact with the reed 8 by means of a guide element and is guided in the usual manner. When the rod 2 is withdrawn, it lies protected inside a tube 1. A guide element 7 matching the cross-section of the tube and in sliding contact with it, e.g. in this embodiment a ring, is arranged at the rear end of the rod 2. The tube 1 is open at its rear end, as shown.

Fig. 3 shows a guide element 7 viewed from the end of the tube 1. The outline of the rod 2 is indicated. The connection of the guide element 7 to the rod 2 by a screw 12 is shown in Fig. 4, in which the arrangement of a toothed rack for driving the rod is also indicated in the longitudinal section through the rod 2. The guide element 7 comprises substantially a cylindrical guide ring 9 covered, for example, with an antifriction layer 11.

By means of this layer, a definite clearance can readily be adjusted between the guide element and the wall of the tube. In this embodiment, the guide ring 9 is carried by radial supports 10 which connect it to the rod 2. The gaps between the supports 10 enable air to pass from one part of the tube 1 to the other during the movements of the rod 2. This flow of air provides cooling during operation.

The guide element 7 may alternatively be in the form of a closure plate with a surrounding ring of beading, or it may be in the form of a piston, and may in some cases be used to move air. As mentioned, the advantage of the invention lies in the improved guiding of the gripper rod, whereby troublesome vibration is prevented and correct transfer of thread is ensured. Effective guidance is provided over the whole length of the gripper rod, from the sliding element of the rod in contact with the reed to the guide element at the rear end of the rod. Between these two locations, the driving and guide unit for the gripper rod, with driving pinion and guide rollers, is arranged in the conventional manner, but one of the guide rollers may be omitted, as mentioned above.

Claims (5)

1. A shuttleless loom including a weft thread insertion device with a gripper rod movable back and forth in the shed, the rod moving within a tube in the rear part of its path of movement, wherein a guide element is in slidable contact with the wall of the tube and is disposed at the rear end of the rod.

2. A loom according to claim 1, wherein the guide element is a cylindrical ring carried by radial supports.

3. A loom according to claim 1, wherein the guide element is a piston.

4. A loom according to any of claims 1 to 3, wherein the guide element is coated with lubricant layer.

5. A shuttleless loom constructed and arranged substantially as herein described and shown in the drawing.