CN106256937B

CN106256937B - Pneumatic device and method for removing a wrong weft from a gripper path of a gripper weaving machine

Info

Publication number: CN106256937B
Application number: CN201610689373.3A
Authority: CN
Inventors: F·拉波利尼; D·波莱蒂; R·纳瓦; W·格里诺尼
Original assignee: Itema SpA
Current assignee: Itema SpA
Priority date: 2015-06-16
Filing date: 2016-06-16
Publication date: 2020-09-15
Anticipated expiration: 2036-06-16
Also published as: EP3106555A1; CN106256937A; JP6856980B2; EP3106555B1; JP2017036534A

Abstract

The invention relates to a device for removing a staggered weft thread from the gripper path in a gripper weaving machine, comprising one or more compressed air flows controlled to open or close by at least one valve (1). The nozzle is arranged on the loom in the region formed between the weft insertion rod (F) and the edge of the fabric being formed and is oriented to form an air jet oriented in a direction away from the thread-feeding gripper guide (G).

Description

Pneumatic device and method for removing a wrong weft from a gripper path of a gripper weaving machine

Technical Field

The present invention relates to a device for removing a wrong weft from a gripper path of a gripper weaving machine and a method for removing a wrong weft using such a device.

More specifically, the invention relates to a device as described above, which temporarily removes the miss-picks outside the shed during the stoppage of the loom caused by the insertion of a miss-pick.

Background

In normal operation of the loom, it may happen that the weft thread is only partially inserted, since the weft thread normally inserted from one side of the loom does not reach the other side thereof. This failure may be due to a defect of the weft yarn or to an excessive pressure exerted on the weft yarn during insertion, causing a mechanical breakage of the weft yarn when it is brought into the shed, or to an early release of the weft yarn from the feed gripper or the pull gripper, or again to the failure of the pull gripper to pick up the weft yarn when the pull gripper is interchanged with the feed gripper in the middle of the shed. In short, the above three irregular weft insertions are represented as:

-the weft-breaking of the weft thread,

-a loss of weft thread,

-a missed interchange between grippers,

or, in general, as "weft staggering".

When one of these irregular weft insertions occurs, the central loom control unit detects it immediately and causes a guided stoppage of the loom, since no weft thread passes through a specific sensor arranged on the receiving side of the loom.

However, such stops (due to the inertia of the parts the loom is moving and depending on the speed of the machine and its height at the stop due to the occurrence of a miss-stitch) usually do not end within the same weft insertion cycle in which a miss-stitch occurs, but rather end during the following cycle. Thus, once a stoppage is determined, it is necessary to back-drive the loom for the number of cycles required (usually one or two cycles) to bring it back to the same position of the insertion of the staggered weft, to remove this weft manually or automatically, and then to restart the loom.

At the above moment of the loom stop performed, a drawback may arise, because the staggered weft (the front of which has reached only the middle point of the shed) is more or less loose, thus forming a loop partly inside the shed and partly outside the shed.

Although the loose weft yarn inside the shed does not cause any inconvenience because it is immediately caught by the skew winding of the warp yarn and the beating up of the reed, the loose weft yarn outside the shed is instead itself arranged along a random path; there is therefore a high risk that it is accidentally caught by the feed gripper at the instant of the idling stop being carried out and is misplaced by such gripper in the shed, possibly causing textile defects. In fact, since the display and weft cutting device has been shut down in synchronism with the loom stop command, the dislocated weft has not been cut off yet, moreover, it is still caught by the weft thread passing through. Therefore, such a drawback may become significant when the staggered weft pulled by the yarn feeding gripper cuts or tears a certain number of warp yarns, depending on the tenacity of the weft yarn, thus increasing the severity of the drawback and prolonging the maintenance time.

The above problems have not been satisfactorily solved by the prior art, which proposes mechanical weft-clamping devices, in the form of electric or pneumatic weft-catching hooks, which complicate the structure of the loom in the area where a large number of devices have been accumulated, and whose speed and efficiency of adjustment are unsatisfactory. In fact, the available time between the loom stop signal and the continuous entry of the feed gripper into the shed during the loom stop is very short; furthermore, the staggering is loose, thus making it difficult for the mechanical hook to catch it.

Disclosure of Invention

The object of the present invention is therefore to provide a device with a completely different concept and operation compared to the conventional devices, which simply and effectively solves the above-mentioned drawbacks, reliably preventing the positioning of a dislocated weft across the inlet path of the threading gripper at the instant of loom stoppage.

This object is achieved by a pneumatic weft insertion removal device and a related method of application having the features of the invention. Further preferred features of such a device and its associated method of application are defined in the dependent claims.

Drawings

Further features and advantages of the pneumatic weft insertion removal device and the relative application method according to the present application will become more apparent by means of the detailed description of a preferred embodiment of the present invention, given purely by way of non-limiting example and depicted in the accompanying drawings, in which:

FIG. 1 is a perspective view of a weft insertion removing device according to the present invention, detached from a loom;

FIG. 2 is a perspective view of the staggered weft removing device of FIG. 1 mounted in place, as seen from the outside (weft insertion side) of the loom; and

fig. 3 is a perspective view of the weft insertion removing device of fig. 2, as seen from the inside (weft insertion side) of the loom.

Detailed Description

As clearly shown in fig. 1, the device for removing weft-miss according to the invention is particularly simple in structure, comprising an electrovalve 1 controlled by the loom control unit, to which a supply 2 of compressed air and a small pipe 3 for air distribution are connected, upstream and downstream respectively, the small pipe 3 having on its lateral surface a series of holes 4 acting as nozzles for the discharge of jets of compressed air.

The electrovalve 1 is small in size and very small in thickness and can therefore be positioned without problems at the side of the sliding guide G of the feed gripper band, as shown in fig. 2, so that the small tube 3 will be arranged parallel to the same guide G (fig. 3) in the region between the weft guide rod F of the weft insertion machine (by which the weft thread to be transferred onto the gripper path for insertion into the shed) and the edge of the forming fabric, i.e. the shed entrance. Obviously, the electrovalve 1 can be replaced by any other type of remotely operated valve.

The small tube 3 is fixed along the guide G such that the hole 4 is arranged to direct the jet of compressed air vertically away from the bringer gripper guide G and preferably upwards. The holes can be aligned longitudinally along the small tubes 3 or can also be slightly staggered from each other laterally, for example alternately arranged, to provide respectively a plurality of jets of compressed air lying on the same plane parallel to the thread feeding gripper guide G or a plurality of jets alternately angled to said plane, so that together they form an air flow with the desired opening angle.

Alternatively, the small tube 3 can be replaced by a special channel formed in the thread feeding gripper guide G, wherein the holes 4 open to form the desired air jet.

The device operation is also particularly simple and effective. The device program contained in the central control unit of the loom provides that, when the central control unit of the loom detects the presence of a wrong weft, in addition to starting the usual loom stop program (which involves braking and stopping the gripper movement in one/two cycles and simultaneously deactivating the weft thread insertion machine, so that said cycle is idle, i.e. no weft insertion), the activation of the electrovalve into the open position is immediately controlled, so that a compressed air flow is ejected from the hole 4 of the small tube 3, causing a lifting action of the loose weft thread located in this region.

The upward lifting of the dislocated weft, effected by the above-mentioned flow of compressed air, spreads itself out from the yarn guide of the rod F of the weft insertion machine concerned and from the fabric formed, to which it is still connected, thus moving away from the feed gripper path rapidly and sharply along its guide G. Thereby, any risk of interference between said dislocated weft and the feed gripper is eliminated in the subsequent idle cycle of the gripper, fully achieving the object of the invention.

The electrovalve 1 is closed once the loom has stopped (or even before its active stop, once the feed gripper has completed its full travel into the shed) and therefore normal miss-repair and loom restart operations can be carried out.

In any case, the present application is not limited to the specific embodiments described above, which are only one possible preferred embodiment, while those different variants are possible, for example as regards the shape and structure of the means which cause said air flow, and the fact that the air flow is conveyed directly, and not indirectly towards the area of interest by means of a conveyor or baffle element. All such modifications are within the reach of a person skilled in the art and therefore they fall within the scope of protection of the invention itself, which is limited only by the following claims.

Claims

1. A device for removing a faulty weft from a gripper path in a gripper weaving machine, comprising one or more compressed air flows controlled by at least one valve (1) to open or close, arranged on the weaving machine in the region formed between a weft insertion rod (F) and the edge of the fabric being formed, characterized in that the compressed air flows are oriented so as to form air jets that facilitate the vertical movement of the faulty weft away from the feed gripper guide (G).

2. Device for removing a dislocated weft from the gripper path in a gripper weaving machine according to claim 1, wherein the air flow is arranged near a feed gripper guide (G).

3. Device for removing staggered picks from the gripper path in a gripper weaving machine according to claim 2, wherein the air flow is injected by a plurality of openings (4) arranged crosswise in the axial direction on the lateral walls of the small tube (3), supplied with compressed air through the electrovalve (1), and associated with a feed gripper guide (G) so that said openings (4) face upwards.

4. Device for removing a staggered weft thread from a gripper path in a gripper weaving machine according to claim 3, wherein the openings (4) are aligned along a line parallel to the axis of the small tube (3).

5. Device for removing a staggered weft from a gripper path in a gripper weaving machine according to claim 3, wherein the openings (4) are staggered alternately on one side and on the other with respect to a line parallel to the axis of the small tube (3).

6. Device for removing dislocated weft from a gripper path in a gripper weaving machine according to claim 3, 4 or 5, wherein the openings are constituted by continuous or discontinuous holes or slits for air channels.

7. Device for removing a dislocated weft from the gripper path in a gripper weaving machine according to claim 2, wherein the air flow is ejected by a plurality of openings provided in the channel of a feed gripper guide (G).

8. A method for removing a wrong weft from a gripper path in a gripper loom in which a loom central control unit initiates a loom fast stop procedure when a wrong weft insertion is detected, said method further comprising: -activating, simultaneously with or immediately after the activation of the loom fast stop program, one or more compressed air flows arranged on the loom in the region formed between the weft insertion rod (F) and the edge of the fabric being formed, characterized in that the compressed air flows are oriented so as to form air jets that facilitate the vertical movement of a wrong weft thread away from a thread-feeding gripper guide (G).

9. Method for removing a wrong pick from the gripper path in a gripper weaving machine according to claim 8 wherein the activation of the compressed air flow is continued at least until the yarn feeding gripper has completed its stroke into the shed.

10. Method for removing a dislocated weft thread from the gripper path in a gripper weaving machine according to claim 9, wherein the compressed air flow comes from near or directly from a feed gripper guide (G) and is directed upwards.