Gripper weaving loom provided with a wear monitoring device of a gripper opener

Abstract

Gripper weaving loom provided with a wear monitoring device of a gripper-opener (1), wherein said gripper-opener (1) causes the opening of gripping means (13) of a gripper (10) of the loom when said gripper (10) slides against a contact edge (3) of said gripper-opener (1) at the exit from the shed. The monitoring device includes at least one conductive wear sensor (4) embedded in the body of said gripper-opener (1), in the proximity of said contact edge (3), and an electric circuit (100) which causes the current to flow through said wear sensor (4), when said wear sensor (4) comes into contact with said gripper (10), following a complete wear of the contact edge (3) portion which covers said wear sensor (4).

Description

[0001] GRIPPER WEAVING LOOM PROVIDED WITH A WEAR MONITORING DEVICE OF A GRIPPER OPENER ★ ★ ★ ★ ★

[0002] FIELD OF INVENTION

[0003] The present invention refers to the field of weaving looms and related monitoring devices . In particular, the present invention refers to a gripper weaving loom comprising a wear monitoring device of a gripper-opener . BACKGROUND OF THE ART

[0004] Among the diverse types of looms used in the weaving industry, the gripper ones are among the best known and most widespread, since , in addition to an excellent precision in weft transporting and a good weaving speed, they also of fer great versatility of production with several types of yarns .

[0005] As is well known to those skilled in the art , in the gripper loom the weft thread insertion system consists of two grippers which cooperate in transporting a weft thread through the shed formed between the warp threads . A carrying gripper hooks a weft thread coming from a weft feeding device on one side of the loom and carries the weft thread to the centre of the shed where it meets a drawing gripper which simultaneously started from the opposite side of the loom . The drawing gripper picks up the weft thread from the carrying gripper, and then draws the weft thread up to the shed outlet . While the grippers return back towards their motion reversal position, outside the shed, the grippers come into lateral contact with respective gripper-openers which cause the opening of the weft thread gripping means provided on the grippers , thanks to the pressure given by the gripper-openers on respective levers or cursors partly pro j ecting from the side of said grippers .

[0006] The gripper-opener is therefore a static element installed on the loom along the gripper path, outside the shed . A suitably shaped contact edge of the gripper-opener is intended to progressively interfere with said lever or cursor for opening the gripping means of the gripper to pick up the weft thread or to release it at the end of the insertion step or even, simply, to allow the cleaning of such gripping means from any residues of weft thread that may have remained caught therein . The opening of the grippers occurs therefore thanks to a high speed, mutual sliding between the gripper lever or cursor and the gripper-opener edge, and such a sliding is repeated several hundred times per minute . In consideration of these conditions of continuous friction, and in order not to cause a rapid deterioration of the gripper, which is an expensive and delicate component , the gripper-opener is made of a significantly softer material than the metal lever or cursor of the gripper, and must therefore be replaced on a regular basis as it is inevitably exposed to a high wear .

[0007] However, visual inspection of the degree of wear of the gripper-opener is not easy to be implemented and therefore a time- scheduled replacement of the gripper-opener is currently adopted, with the inevitable risks of discarding grippers which are still capable of carrying out their task or weaving with gripper-openers already excessively worn, which can lead to an increase in errors in the weft thread insertion or even to a deterioration of the gripper itself .

[0008] It is therefore evident how useful would be a monitoring device which could automatically monitor the achievement of the gripper-opener maximum allowable wear threshold, which monitoring device would in fact allow the loom workers to replace the gripperopeners at the most correct time , i . e . , before the quality of the fabric can be compromised or the grippers deteriorate, but not before the wearable thickness of a gripper-opener contact edge has been entirely consumed .

[0009] The technical problem addressed by the present invention is therefore to provide a wear monitoring device of a gripper-opener which is suitable for operating without interrupting the loom operation, in an area where there is already a thick concentration of devices and therefore the available residual space is extremely limited . This monitoring device must also consider the fact that on the gripper-opener contact edge there is a continuous physical contact with the gripper, which prevents the positioning of wear detecting sensors on such an edge .

[0010] Within this technical problem, a first ob ject of the present invention is therefore to first provide a gripper-opener wear monitoring device having a low bulk .

[0011] A second obj ect of the present invention is to provide a gripper-opener wear monitoring device which does not require assembling and disassembling of the device itself during the frequent replacements of the gripper-opener .

[0012] Finally, a third ob ject of the present invention is to provide a gripper-opener wear monitoring device which does not require the presence of sensors or other fixed elements positioned in front of the gripper-opener contact edge . SUMMARY OF THE INVENTION

[0013] This problem is solved, and these ob jects achieved, by means of a weaving loom comprising a gripper-opener wear monitoring device having the features defined in claim 1 . Other preferred features of said wear monitoring device of a gripper-opener are defined in the secondary claims .

[0014] BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Further features and advantages of the loom comprising a wear monitoring device of a gripper-opener 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 non-limiting example and illustrated in the accompanying drawings , wherein :

[0016] Fig . 1 is a plan view of a drawing gripper of a gripper weaving loom;

[0017] Fig . 2 is a perspective view of a gripper-opener equipped with wear sensors of the monitoring device according to the present invention;

[0018] Fig . 3 is a plan view of the gripper-opener of Fig . 2 ;

[0019] Fig . 4 is an enlarged perspective view of one of the wear sensors of the monitoring device according to the present invention ;

[0020] Fig . 5 is an electric circuit forming part of the monitoring device according to the present invention; and Fig . 6 is a perspective view of a gripper-opener incorporating the monitoring device according to the present invention, mounted in place , during the passage of a gripper in front of the gripper-opener . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0021] According to the present invention, to solve the problem highlighted above through a constructively simple , low bulk and easy to apply solution, the Applicant envisaged inserting inside the gripper-opener, at least one wear sensor consisting of a conductive element and a related electric power supply circuit . In standard conditions aid electric circuit is an open circuit because the wear sensor is kept insulated by the gripper-opener plastic material itself . The aforementioned electric circuit is , in fact , made up of a power supply section, including an electric power supply that applies a voltage to the wear sensor, and a closing section, which is electrically connected to the power supply section only when the wear sensor becomes uncovered, due to the progress of wear of the contact edge of the gripper-opener, and comes therefore into contact with said closing section of the electric circuit . The electric current thus consequently circulating in the electric circuit can be detected, providing a direct and reliable signal that the gripper-opener wear limit has been reached .

[0022] According to an important feature of the invention, in order to reduce the complexity and bulk of the control device of the present invention and also avoid the need to disassemble and reassemble the control device or at least a portion thereof at each replacement / reversal of the gripper-opener, the closing section of the aforementioned electric circuit is advantageously formed by a not-wired electric circuit comprising electrically conductive loom components already usually present on board the loom .

[0023] Going now into greater detail , the present invention is described with reference to a negative drawing gripper 10 , shown in fig . 1 . Those skilled in the art will naturally have no dif ficulty in applying the same inventive principle to positive drawing grippers or to carrying grippers .

[0024] The drawing gripper 10 is made up of a body 11 with a hook

[0025] 12 at its front end to hook a weft thread which remains clamped between the hook 12 inner wall and the tip of a rod 13 which is axially movable inside the gripper 10 and kept elastically pushed against the hook 12 by spring means (not shown in the drawing) . In Fig . 1 it can also be noted a cursor 14 , laterally pro jecting from the body 11 of the gripper 10 , which cursor causes the rod

[0026] 13 to move in contrast to said spring means when the cursor 14 is progressively pressed by the contact edge 3 of the gripper-opener 1 , thus releasing the weft thread after it has been completely inserted into the shed .

[0027] Figs . 2 and 3 schematically show a gripper-opener 1 in which a portion of the wear monitoring device of the gripper-opener according to the present invention is installed . The gripperopener 1 consists of a profile of suitably shaped plastic material, the outer layer of which is formed of a material having a low friction coefficient such as , for example, a polyester resin, which material also offers a lower abrasion resistance than the metallic material which the cursor 14 of the drawing gripper is made of . These requirements are necessary, on the one hand, to minimize the friction force generated during the sliding of the cursor 14 of the drawing gripper on the gripper-opener 1 and, on the other hand, to ensure that the developed friction force exclusively causes wear on the gripper-opener 1 , without damaging the drawing gripper metal cursor 14 .

[0028] The gripper-opener 1 is fixed in correspondence with the drawing gripper guide , by means of fixing means housed in through holes 2 formed in the gripper-opener, so that when the drawing gripper passes in front of the gripper-opener 1 the relative cursor 14 slides against a contact edge 3 of the gripper-opener 1 . The contact edge 3 of the gripper-opener 1 is then shaped in such a way as to be slightly inclined with respect to the forward direction of the drawing gripper 10 , so as to cause a desired progressive pressure on the operating cursor 14 , which thus operates the mobile rod 13 of the drawing gripper 10 , when this last runs in front of the gripper-opener 1 . As already well known, to increase their service life each single gripper-opener 1 is symmetrically shaped on the two sides , so that when a contact edge 3 of the gripper-opener is completely worn, the gripper-opener 1 can be disassembled, rotated by 180 ° on the same plane, and reassembled in its working position to carry out its function with its opposite, still intact , contact edge 3 .

[0029] Referring again to Figs . 2 and 3 it can be noted that , according to a main feature of the invention, two wear sensors 4 are inserted inside the gripper-opener 1 , which operation being explained in detail below . The wear sensors 4 have the preferred shape illustrated in the enlarged detail of Fig . 4 and are made of a conductive material, a copper-based alloy being particularly preferred for this purpose . Each wear sensor 4 comprises a plate 5 , preferably having the shape of an equilateral triangle with rounded corners , on one vertex of which an electric connection hole 6 is formed, while two contact pins 7 pro ject from the opposite vertices . The two contact pins 7 have a cylindrical, or anyway rounded, shape towards the outside of the plate 5 where they are intended to contact the cursor 14 of the drawing gripper when the wear of the gripper-opener 1 contact edge 3 reaches its upper limit . In Figs . 2 and 3 , it is in fact clearly illustrated how the two wear sensors 4 are embedded in the gripper-opener 1 at appropriately staggered and opposite positions in the proximity of the centre thereof , so that the two contact pins 7 of each wear sensor 4 extend parallel to a respective contact edge 3 of the gripper-opener and at a distance therefrom corresponding to the maximum thickness of permissible wear of the gripper-opener 1 .

[0030] In Fig . 5 an electric circuit 100 of the wear monitoring device of a gripper-opener 1 according to the present invention is illustrated . A power supply section of the electric circuit 100 includes an electric power supply 102 , a resistance 103 and a wear sensor 4 of the gripper-opener 1 , connected in series with each other through a traditional wiring; a voltmeter 104 further allows to monitor the variations over time in the potential dif ference across the resistance 103 . A closing section of the electric circuit 100 is , instead, a not-wired improper circuit consisting of conductive components of the loom itself and, specifically, a guide group 106 of a gripper strap, a gripper strap 107 , and finally a drawing gripper 10 and, in particular, its outer cursor 14 . Note that all the elements of the closing section of the electric circuit 100 are suf ficiently conductive because they are made of metallic materials - such as the guide group 106 and the carrying gripper 10 - or of carbon fibre - such as the gripper strap 107 - and this closing section of the electric circuit allows therefore the electric circuit 100 to be closed - when the contact edge of the gripper 3 is completely worn and therefore the wear sensor 4 comes into direct contact with the cursor 14 of the drawing gripper 10 - without the need to install any type of dedicated wiring, thus obtaining a significant simplification in the configuration of the control device . Finally, the two ends of the electric circuit 100 are connected to a common equipotential reference 101 , which can be the same loom metal structure .

[0031] In normal conditions the power supply section and the closing section of the electric circuit 100 are therefore mutually separated and isolated by the contact edge 3 of the gripper-opener 1 , which separates the wear sensor 4 and, in particular, its contact pins 7 from the cursor 14 of the gripper 10 . The contact edge 3 thickness covering the contact pins 7 is defined when recesses housing the wear sensor 4 are formed by machining, and it corresponds to the gripper-opener 1 maximum allowable wear . This thickness of maximum wear is , for example , 1 mm . Under ordinary wear conditions , the wear sensors 4 are covered by the contact edge 3 of the gripper-opener 1 and therefore they do not come into electric contact with the cursor 14 of the gripper 10 . When, instead, due to friction with the cursor 14 , the entire thickness of the contact edge 3 covering the contact pins 7 gets worn out , the wear sensor 4 are exposed on the gripper-opener 1 surface , coming into electric contact with the cursor 14 of the gripper 10 and thus closing the electric circuit 100 . As the electric circuit 100 is closed, a current circulation is caused in the electric circuit 100 and then a potential difference across the resistance 103 arises , which potential difference is detected through the voltmeter 104 . Any other current detector can be naturally used for this purpose .

[0032] Furthermore, the electric circuit 100 is coupled, in a per se well-known way, with visual and / or auditory warning means to alert the operators to replace / rotate the gripper-opener 1 . Alternatively, it is also possible to directly send a signal of the electric circuit 100 being closed to a control unit of the loom, to initiate a programmed halt of the weaving operations , before excessive wear of the gripper-opener 1 can cause inhomogeneity or irregularities in the fabric being processed .

[0033] From the previous description it should appear clearly how the wear monitoring device of a gripper-opener in a gripper weaving loom, according to the present invention, has fully achieved all the intended obj ects . Such a device is in fact partly embedded in the gripper-opener 1 thickness and partly consists of an electric circuit having a minimal bulk, considering that the whole closing section of such a circuit consists of conductive elements of the same weaving loom .

[0034] The electric connection between the wear sensor 4 and the electric circuit can easily and ef fectively be made via a static contact consisting of a conductive pin integral with a seat of the gripper-opener and electrically connected to the power supply section of the electric circuit 100 , which conductive pin automatically engages within the hole 6 of the wear sensor 4 when the gripper-opener 1 is fixed in its normal work position; therefore , no additional assembly / disassembly operation is necessary to get the electric connection of the wear sensor 4 with the electric circuit 100 , more than the known assembling operation of the gripper-opener 1 in its seat .

[0035] Finally, the monitoring device of the invention does not include any element positioned in front of the gripper-opener, since the wear sensors are positioned precisely inside the gripper-opener 1 itself . Therefore , no obstacle or additional friction is generated in the gripper path by said monitoring device .

[0036] It is understood, however, that the invention should not be considered as limited to the specific arrangements illustrated above , which are only exemplary embodiments thereof , but that dif ferent variants are possible, all within the reach of a person skilled in the art , without thereby departing from the scope of protection of the invention itself , which is only defined by the following claims .

Claims

CLAIMS1) Gripper weaving loom provided with a wear monitoring device of a gripper-opener (1) , wherein said gripper-opener (1) causes the opening of gripping means (13) of a gripper (10) of the loom when said gripper (10) slides with its cursor (14) against a contact edge (3) of said gripper-opener (1) , characterized in that said monitoring device includes at least one conductive wear sensor (4) embedded in the body of said gripper-opener (1) at a predetermined distance from said contact edge (3) , said distance defining a thickness of maximum wear of the contact edge (3) , an electric circuit (100) comprising a power supply section which applies a voltage to said wear sensor (4) and a non-wired closing section which comprises electrically conductive components of the loom and a current detector signalling a passage of current in the electric circuit (100) when said wear sensor (4) comes into contact with the cursor (14) of said gripper (10) following a complete wear of said thickness of maximum wear of said contact edge (3 ) .2) Gripper weaving loom provided with a wear monitoring device of a gripper-opener (1) as in claim 1, wherein said power supply section and said closing section of the electric circuit (100) are mutually separated by said thickness of maximum wear of the contact edge (3) , and their ends are connected to a same equipotential reference (101) .3) Gripper weaving loom provided with a wear monitoring device of a gripper-opener (1) as in claim 2, wherein said power supply section of the electric circuit (100) includes an electric power supply (102) , a resistance (103) , and said wear sensor (4) of the gripper-opener (1) , connected in series.4) Gripper weaving loom provided with a wear monitoring device of a gripper-opener (1) as in claim 2, wherein said closing section of the electric circuit (100) consists of a non-wired electric circuit including a guide group (106) of a gripper strap, a gripper strap (107) , a gripper (10) , and a cursor (14) of said gripper all made of electrically conductive materials.5) Gripper weaving loom provided with a wear monitoringdevice of a gripper-opener (1) as in claim 2, wherein said equipotential reference (101) is the loom metal structure.6) Gripper weaving loom provided with a wear monitoring device of a gripper-opener (1) as in claim 1, wherein said wear sensor (4) includes one or more contact pins (7) extending parallel to a respective contact edge (3) of the gripper-opener (1) , at a distance therefrom corresponding to said thickness of maximum wear of the contact edge (3) .7) Gripper weaving loom provided with a wear monitoring device of a gripper-opener (1) as in claim 6, wherein said wear sensor (4) includes a plate (5) integral with said contact pins (7) and provided with an electric connection contact (6) to said first power supply section of said electric circuit (100) .8) Gripper weaving loom provided with a wear monitoring device of a gripper-opener (1) as in claim 7, wherein said plate (5) has the shape of an equilateral triangle with rounded corners, said electric connection contact (6) being provided on one of its vertices, while said contact pins (7) project from the opposite vertices .9) Gripper weaving loom provided with a wear monitoring device of a gripper-opener (1) as in claim 8, wherein said electric connection contact (6) is a hole suitable for engaging with a conductive pin integral with a seat of the gripper-opener (1) and electrically connected to the power supply section of the electric circuit (100) .10) Gripper weaving loom provided with a wear monitoring device of a gripper-opener (1) as in any one of the preceding claims, wherein said monitoring device includes two wear sensors (4) at the two opposite contact edges (3) of the gripper-opener (1) •

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