GB2128212A - Weft thread insertion device for a shuttleless loom - Google Patents

Abstract

A rigid gripper rod (2) (Figure 1) of a shuttleless loom has at its rear end a guide member in the form of a piston (3) and valves (5) are arranged in the piston head so that a directed air stream can be produced inside the tube (1) during the forward the return movement of the gripper rod. The air stream is utilised for cooling or cleaning purposes. <IMAGE>

Description

SPECIFICATION Weft thread insertion device for a shuttleless loom.

This invention relates to a weft thread insertion devicefora shuttleless loom, comprising gripper rods movable into and out of the shed. Such a loom normally has a tube into which the gripper rod is introduced on its return movement. This tube not only protects the operator against injury but also protects the gripper rod in this position. It is known to provide a guide surface at the rear end of the gripper rod to make sliding contactwith the wall of the tube in orderto provide improved guidance and supportforthe gripper rod and reduce its tendency to vibration and thereby improve transfer of the weftthread. This guide surface may be, for example, in the form of a piston with perforations between a cylindrical ring forming the guide surface and the radial supports carrying the ring.The perforations between the supports enable airto flow inside the tube during displacementofthe piston.Theairflowobtained is, however, uncontrolled and can only be used to a limited extent for cooling.

Aweftthread insertion device having gripper rods movable forwards and backwards has been described in FR-PS 20 60 258. In this specification, an insertion device in the form of a rod is displaced by means of an electric linear motor and is supported in a sliding bearing. A rearward extension to the rod is provided to enable the moving masses to be received elastically at the ends ofthe forwards and backwards movements.

This extension passes through a cylinder and is supported in sleeves at the two closed cylinder ends.

Inside the cylinder, the rod carries a piston which compresses the air atthe ends of the cylinders and thus elastically absorbs the movement. The elastic effect desired may be adjusted atthe ends ofthe cylinder by openings in the cylinder wall which may be covered to a varying degree. Instead of compressed air cushions, mechanical springs may be provided at the ends ofthe cylinder. Theairtransported bythe moving piston is not utilized for any other purpose, and in particular no means are provided for the passage of airfrom one end ofthe piston to the other as in the apparatus mentioned previously.

Itis an object of the present invention to control and to use the uncontrolled passage ofairthrough the guide pistons ofthe gripper rods.

According to the invention, the piston is provided with means for producing a directed air stream.

The means for producing a directed air stream may be, for example, mechanically or aerodynamically operating valves. The directed air stream not only provides improved cooling of the guide tube along its length but may also be directed, for example, to the bearing unit or driving unitofthegripperrod. In addition, the arrangement may be used as air pump, and air an duct, e.g. a hose, may be attached, say, to the end of the guide tube to eject the air carried by the piston at some other location, the site of operation,.

where it may be used for cooling and other purposes such as the removal of dust and the like.

Embodiments of the invention will now be de scribed by way of example with reference to the drawing, in which Figure lisa section on the planeA-A of Figure 2 through a gripper rod with a guide piston, and a guide tube; Figure 2 is a cross-section on the plane B-B of Figure 1; Figure 3 illustrates the use ofthe device for cooling purposes; and Figure 4 illustrates the use ofthe device as a pump.

Referring to the drawing, a piston 3 slides along a wall of a guide tube 1. The piston is attached to the end of a gripper rod 2 equipped with a rack, e.g. by means of a screw 4. The arrangement of a rack in a gripper rod 2 and the alternating drive of the gripper rod by a pinion is known and need not befurtherdescribed. In Figure 2, the cross-section of the gripper rod is indicated in dashed lines. The piston 3 may, for example, have an anti-friction layer.

Valves arranged in the piston head allow airto flow through in one direction only. The valves may be of various types. In present embodiment, aerodynamic valves 5 are used. When the piston moves to the left (Figure 1),airflows into the piston from left to right as indicated by the arrows and flows outto the right.

When the piston moves in the opposite direction, i.e.

when the gripper rod is pushed forwards to the right, eddy formation causes a slight flow of air through the valve and the net flow isto the right due to the difference in the quantities of air flowing through. It is advantageous to arrange several valves uniformly around the head ofthe piston 3, Figure 2.

Figure 3 schematically represents a simplified embodiment in which the device is used for cooling the bearing and drive of the gripper rod. The guide tube 1 is at least partially open at its left-hand end 1 a and its right-hand end 1 b. The gripper rod 2 with the gripper head 2a at one end is driven in alternating directions by a driving pinion 8. Horizontal guide rollers6and avertical guide roller7 guidethegripper rod. Assuming thatthe valves are installed to operate as illustrated in Figure 1, movement of the gripperto the right, as indicated bythe arrow,therefore causes air situated to the right of the piston 3 in the tube 1 to flow to the right th rough the end 1 b ofthetube as indicated by the arrows. The air is ejected so asto cool the bearing and driving parts 6,7 and 8.At the same time, air enters the tube atthe left end 1 a to fill the part of tube to the left of piston 3. When the piston moves in the opposite direction, i.e. when the gripper rod 2 is withdrawn into the tube 1, airflows through the valves 5 in the piston 3 to fill the part of the tube 1 to the right ofthe piston. Aflowof airthrough thetubetothe right similarto thatof Figure 1 is therefore obtained. This flow not only cools the bearings of the gripper rod as mentioned above but also the tube 1 and the piston 3.

In Figure 4, it is assumed that the flow of air is in the opposite direction, i.e. the valves in piston 3 function in the opposite direction to that shown in Figures 1 and 3. The overall construction is not substantially diffe rentfrom that of Figure 3, but the end 1 a of the tube is closed. An outflowwith an airduct9connected thereto is provided at that end ofthe tube. The air duct 9 leads to the site of operation, e.g. a location close to the weft thread shears, where pieces of th read waste are required to be blown away.

Since the airflows through the tube 1 from right to Ieftwhenthe device is arranged asa pump in Figure 4, every withdrawal ofthe gripper rod and every movement ofthe piston 3 to the left carries air through the duct 9to the operating site where it is ejected through a nozzle 10.

Many other different possible applications are conceivableforthe use ofthe device as an air pump.

For example, it may be useful to install an air reservoir 11 or other storage apparatus in the air duct 9.

The possibility of a doubleuseofthegripperrod guide, both for improved guidance and prevention of vibration and for delivering air in a particular direction, in all cases provides considerable advantages since no additional apparatus is then required for producing an air stream.

Claims (7)

1. Weftthread insertion deviceforashuttleless loom, having a gripper rod movable into an enveloping tube in the rear part of its path of movement and having a guide surface at its rear end in the form of a piston slidably in contactwith the wall of the tube, wherein the piston has means for producing a directed air stream.

2. A device according to claim 1, having valves in the piston.

3. Adevice according to claim 2, having aerodyna micvalvesinthe piston.

4. A device according to any preceding claim, wherein the air stream is directed towards a bearing and driving unit of the gripper rod.

5. A device according to any of claims 1 to 3, when used as an air pump and having an air duct connected to the guide tube to carry air to a site of operation.

6. A device according to claim 5, having an air reservoir in the air duct.

7. Weft thread insertion deviceforashuttleless loom constructed and arranged substantially as herein described and shown in the drawings.