Support for main launching nozzles of an air loom, said nozzles being equipped with brush means for retaining the weft threads

Abstract

A support (A) for the main launching nozzles of an air loom, wherein said main launching nozzles comprise components forming compressed air jets and components launching the weft threads and are equipped with brush means (1) for retaining the weft threads. Said support (A) comprises a rear part of the support (A1) and a front part of the support (A2), which are distinct and mutually adjacent at a connection surface of the support where seats (4, 5) housing one or more of said brush means (1) are provided.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to an improved support for main launching nozzles of an air loom, said nozzles being equipped with brush means for retaining the weft threads.BACKGROUND OF THE PRIOR ART

[0002] As widely known, the weaving operation in an air weaving loom involves the insertion of a succession of weft threads within a shed formed between a plurality of mutually parallel warp threads, divided apart into two subgroups, according to variable patterns, by means of a weaving machine which controls the motion of the warp threads to obtain a predefined design of the fabric being formed.

[0003] Insertion of the weft threads into the warp shed can be carried out in different ways. In air weaving looms, the weft threads are inserted into the shed by using one or more compressed air main launching nozzles, each of which houses a weft thread. When a specific weft thread must be inserted into the shed, the respective main launching nozzle is supplied with compressed air to form an air jet which launches the weft thread into the shed. Secondary nozzles, also supplied with compressed air, are then arranged at regular intervals along the warp shed to emit air jets which are appropriately directed to sustain and push the weft thread along the reed channel up to the exit from the shed, on the side of the loom opposite to its insertion side.

[0004] A typical problem of this configuration - particularly significant when using weft threads containing elastic fibres - is that of maintaining each weft thread duly inserted into its respective main nozzle in a stable manner during the weaving operation, i.e. preventing the weft thread from coming out upstream of the nozzle when, once fully inserted, the weft thread is cut. During the insertion operation, in fact, the weft thread is kept taut and correctly inserted inside the main nozzle by the dynamic pressure of the compressed air jet; therefore, when the weft thread is cut, at the end of its insertion, an elastic recovery of the previously taut textile fibres occurs, which recovery can cause the free end of the weft thread just cut to move back along the main nozzle until coming out from the same. When exit of the weft thread from its respective nozzle takes place, it is obviously necessary to stop the loom and correctly reinsert the weft thread in position, with unavoidable reduction in productivity, increase in costs and onset of possible defects in the fabric.

[0005] EP-2226416 (2010) solved the above problem in a particularly simple and effective way by inserting inside each main nozzle, downstream of the component forming the compressed air jet, a cylindrical ring equipped with bristles slightly convergent towards the forward direction of the weft thread (hereinafter also simply referred to as "brush" or "brush means"). As a matter of fact, the weft thread freely flows through the brush means during the insertion operation, but when the weft thread is cut, any possible retrograde motion of its free end is immediately and effectively stopped by the brush means, around the bristles of which the weft thread remains entangled. EP-2778268 (2014), EP-3023525 (2016) and EP-3342910 (2018) disclose as many different subsequent embodiments of the same inventive principle disclosed by EP-2226416.

[0006] Figs. 1a and 1b show a nozzles assembly which comprises four main launching nozzles according to the technical solution disclosed by EP-2226416. The nozzles assembly comprises a support A equipped with several cylindrical seats S having convergent axes, one for each main nozzle controlling a respective weft thread. A component forming a compressed air jet including a respective injector P is inserted into each of such seat S, at the weft thread inlet side; this is a device designed for guiding the weft thread inside and adequately convey a flow of compressed air with its external surface to obtain a compressed air jet correctly directed around the weft thread. At the weft thread exit side from the support A, a weft thread launching component is sealingly inserted into each of said seats S. The weft thread launching component comprises a base body C and straight launch tubes L, said launch tubes L being convergent towards a head clamp M which keeps their ends in a stable position closely adjacent to the mouth of the reed R launching channel. The compressed air is sent into the seats S via special ducts formed inside the support A and ending with openings O on a side wall of the support A. Finally, quick couplings N are mounted in the openings O to allow the quick coupling of flexible tubes T supplying compressed air. The innovation disclosed by EP-2226416 precisely consists in inserting the aforementioned brush means 1 into the base bodies C of the launch tubes L.

[0007] However, in the face of the high effectiveness and simplicity of the solution proposed, a significant technical drawback has been highlighted when using this device, consisting in the complexity of the cleaning operations of the brush means 1. Such operations are in fact periodically necessary to maintain unaltered the brush functionality, which is gradually compromised due to the entanglement, on the brush bristles, of textile fibres detached from the weft thread passing therethrough. Such an entanglement of textile fibres hinders in fact the free motion of the bristles, making the brush means less efficient, and finally hindering the retaining function of the weft thread in a direction opposite to the usual insertion direction into the fabric being woven.

[0008] A maintenance or replacement operation of the brush means may also be required when the operator, by incorrectly extracting the weft thread from the nozzle insertion side, may cause deformation of the brush bristles or breakage of the weft thread with consequent entanglement of the same on the brush bristles.

[0009] In all the known devices cited above, the cleaning / replacement of the brush means 1, to restore their regular operability, necessarily requires opening the clamp M, disassembling the individual launch tubes L from the support A and then opening the base body C of each of said launch tubes L, so that the brush means 1 can be extracted and cleaned / replaced. In EP-3342910, in particular, also the component forming the compressed air jet needs to be preliminarily disassembled, since the structure with internal abutment of the launch tubes allows the brush means to be disassembled only from the rear side of the nozzle support. In all the known solutions cited above, this is therefore a particularly time-consuming operation, which also requires particular attention by the operator, during reassembly, to correctly centring the diameters of the coupled parts, insert the brush means into their seat without damaging the bristles, correctly tighten the screws which close the clamp M and / or those fixing the nozzle support to the loom sley. Finally, provision must normally be made for a final step of recalibration of the compressed air jets, as the reassembly operation cannot guarantee the identical re-establishment of the previous geometric positions of the individual components of the main nozzles.

[0010] The above drawback, in addition to causing significantly long processing times for the brush cleaning operation, also necessarily requires this operation to be carried out by a specialized textile operator, capable of correctly assembling the components and then calibrating the compressed air jets.

[0011] The technical problem addressed by the present invention consists therefore in providing a support for the main nozzles of an air loom, which allows the cleaning or replacement operation of the brush means of a main nozzle of an air loom to be simplified.

[0012] Within the extent of this technical problem, a first object of the present invention is to reduce the working times of the maintenance operation, i.e., cleaning or replacement, of said brush means.

[0013] A second object of the invention is then to prevent the maintenance operation from modifying the geometric arrangement of the components determining the performance of the compressed air jets, so that the step of calibrating said air jets after completing the maintenance operation can be eliminated.SUMMARY OF THE INVENTION

[0014] This problem is solved, and these objects achieved, by means of a support for the main launching nozzles of an air loom, provided with brush means for retaining a weft thread, having the features defined in claim 1. Other preferred features of said support for main launching nozzles are defined in the secondary claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Further features and advantages of the support for the main launching nozzles according to the present invention will anyhow become more evident from the following detailed description of a preferred embodiment of the same, given by mere way of nonlimiting example and illustrated in the accompanying drawings, wherein: Figs. 1a and 1b (PRIOR ART) show a traditional main launching nozzles assembly, provided with retaining brush means, in an assembled and exploded view, respectively; Fig. 2 is a perspective view of a main launching nozzles assembly including a support for main launching nozzles according to the present invention, mounted on an air loom and in a closed working configuration; Fig. 3 is a view similar to Fig. 2, wherein the nozzle support is in an open configuration for a maintenance operation of the brush means; Fig. 4 is a plan and sectional view, on an enlarged scale, of the main launching nozzles assembly alone, including a main launching nozzle support according to the present invention, in a closed working configuration; Fig. 5 is a view similar to Fig. 4, wherein the nozzle support is in an open configuration for a maintenance operation of the brush means; and Fig. 6 is a perspective view of the main launching nozzles assembly in the open configuration of Fig. 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0016] As illustrated in Figs. 2-6, to solve the problem highlighted above by means of a constructively simple and effective solution, according to a first feature of the present invention the support for a main launching nozzles assembly is made up of two distinct parts. More precisely, a rear part of the support A1 comprises the components forming the air jets, while a front part of the support A2 comprises the components launching the weft threads, i.e., the launch tubes L and any accessories thereof. The two rear part A1 and front part A2 are mutually adjacent at a connection surface and independently fixed to a common base 3 which is in turn fixed to the loom sley B (Fig. 6), by means of screws V1 and V2, respectively, of adequate section and easy accessibility.

[0017] Furthermore, in accordance with a second feature of the invention, seats housing the brush means 1 are formed precisely at said connection surface between the rear part of the support A1 and the front part of the support A2.

[0018] Thanks to this construction, immediate and simultaneous access to all the brushes 1 of the main nozzles assembly can be therefore obtained, by simply freeing from the fixing screws V1 the rear part of the support A1, i.e. the part which is connected to the compressed air supply tubes T. As a matter of fact, since said tubes T are usually of the flexible type, the rear part of the support A1, thereby released from the base 3, can be easily detached from the front part of the support A2 to the necessary extent to allow convenient access to or disassemble the brushes 1, without any need to disconnect or disassemble the components forming the compressed air jets, housed in the rear part of the support A1 of the nozzles assembly.

[0019] As stated above, in fact, the seats housing the brush means 1 are formed at the connection surface of the two parts - rear A1 and front A2 - of the support and the brushes 1 are thus immediately accessible upon detachment of the rear part of the support A1 from the front part of the support A2. Said front part of the support A2 remains integral with the base 3 thanks to the fixing screw V2, without therefore altering the alignments of the launch tubes L with respect to said base 3 and to clamp M. In the illustrated embodiment, the seats housing the brush means 1 are allotted between the two parts of the support A and precisely, as better shown in Fig. 5, for each brush means 1 in the rear part of the support A1 a first cylindrical seat 4 is formed, wherein the cylindrical ring of the brush means 1 is housed, while in the front part of the support A2 a second conical seat 5 is formed wherein the convergent bristles of the brush means 1 are housed. In an alternative embodiment, both the first housing seat 4 and the second housing seat 5 are formed in the front part of the support A2. The illustrated embodiment is preferred because the bristles of the brushes 1 turn out immediately visible (Fig. 3) when the rear part of the support A1 is detached and thus the cleaning operation of said bristles can be performed even without removing the cylindrical rings of the brush means 1 from their respective cylindrical seats 4.

[0020] The pneumatic seal of the mating surfaces of the rear part of the support A1 and the front part of the support A2 is obtained by simple contact between said surfaces, or by interposing between them a membrane acting as a gasket, or other types of airtight gaskets, all well-known per se.

[0021] Once the cleaning / replacement operation of the brush means 1 has been carried out, positioning again the rear part of the support A1 on the front part of the support A2 is facilitated by suitable guide elements which make thereby easier a correct insertion of the brushes 1 bristles into their respective conical seats 5 without damaging them. In the illustrated embodiment, said guide elements consist of cylindrical pins 6 and corresponding holes 7 respectively formed in the two parts A1 and A2 of the support A, but any other centring device known per se can obviously be used as well.

[0022] From the preceding description it should be clear how the present invention has fully achieved all the desired objects. The provision of a support A consisting of two separate parts A1 and A2 - mutually adjacent, independently fixed to a common base, and therefore easily and rapidly separable - as well as the provision of seats for the brush means at the connection surface between said two parts - rear A1 and front A2 - of the support A, allow in fact extremely rapid and easy access to the brushes 1, without requiring disassembly of any other component of the nozzles assembly, thus achieving the first object of the invention.

[0023] Furthermore, the very fact that none of the other components of the nozzles assembly is disassembled during the detachment of the rear part of the support A1 ensures that the relative position of said components - in particular that of the injectors P with respect to the seats S and that of the launch tubes L with respect to the front part of the support A2 and to the clamp M - is not changed and therefore the fluid-dynamic features of the compressed air jets are not changed. This allows therefore the nozzles assembly to be restarted in operation, after the cleaning or replacement operations of the brushes 1, without the need to perform a new calibration of said compressed air jets, thus also achieving the second object of the invention.

[0024] However, it is understood that the invention should not be considered as limited to the specific arrangements illustrated above, which are only exemplary embodiments thereof, but that different variants are possible, all within the reach of a person of ordinary skill in the art, without thereby departing from the scope of protection of the invention itself, which is only defined by the following claims.

Claims

1. Support (A) for the main launching nozzles of an air loom, wherein each main launching nozzle comprises, upstream, a component forming a compressed air jet, and, downstream, a component launching the weft thread, and wherein each main launching nozzle is furthermore provided with brush means (1) for retaining the weft thread, characterised in that said support (A) consists of at least a rear part of the support (A1) and at least a front part of the support (A2), which are distinct and mutually adjacent at a connection surface of the support (A), and in that at said connection surface of the support (A) housing seats (4, 5) for housing one or more of said brush means (1) are provided.

2. Support for the main launching nozzles of an air loom according to claim 1, wherein said rear part of the support (A1) comprises the components forming compressed air jets and said front part of the support (A2) comprises the components launching the weft threads.

3. Support for the main launching nozzles of an air loom according to claim 2, wherein said rear part of the support (A1) and said front part of the support (A2) are independently fixed to a same base (3), by means of respective removable fixing means (V1, V2), so that they are mutually adjacent at said connection surface of the support.

4. Support for the main launching nozzles of an air loom according to claim 3, wherein the housing seats of said brush means (1) comprise, for each brush means (1), a first seat (4) housing a ring equipped with bristles of the brush means (1) and a second seat (5) housing said bristles of the brush means (1).

5. Support for the main launching nozzles of an air loom according to claim 4, wherein said first seat (4) is formed in the rear part of the support (A1) and said second seat (5) is formed in the front part of the support (A2).

6. Support for the main launching nozzles of an air loom according to claim 4, wherein said first seat (4) and said second seat (5) are both formed in the front part of the support (A2).

7. Support for the main launching nozzles of an air loom according to any one of claims 4 to 6, wherein said ring with bristles is cylindrical and said bristles are convergent, and wherein said first seat has a cylindrical shape and said second seat has a conical shape.

8. Support for the main launching nozzles of an air loom according to any one of claims 3 to 7, wherein guide elements are further provided to facilitate a correct mutual positioning between the rear part of the support (A1) and the front part of the support (A2), when these parts are arranged mutually adjacent at said connection surface of the support.

9. Support for the main launching nozzles of an air loom according to claim 8, wherein said guide elements consist of pins (6) and corresponding holes (7) respectively formed in one and the other of said rear part of the support (A1) and front parts of the support (A2).

10. Support for the main launching nozzles of an air loom according to any one of claims 3 to 7, wherein sealing gaskets are further provided at said connection surface between the rear part of the support (A1) and the front part of the support (A2).

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