Gripper loom equipped with a wear monitoring device for the gripper opener.

Abstract

A gripper loom equipped with a wear monitoring device for a gripper opener (1), wherein the gripper opener (1) releases the gripping means (13) of the gripper (10) when the gripper (10) slides against the contact edge (3) of the gripper opener (1) at the exit from the reed. The monitoring device includes at least one conductive wear sensor (4) embedded in the body of the gripper opener (1) near the contact edge (3), and an electrical circuit (100) that supplies current to the wear sensor (4) when the portion of the contact edge (3) covering the wear sensor (4) is completely worn and the wear sensor (4) comes into contact with the gripper (10).

Description

Technical Field

[0001] The present invention relates to the field of weaving machines and related monitoring devices. In particular, the present invention relates to a gripper loom including a wear monitoring device for a gripper opener.

Background Art

[0002] Among various types of weaving machines used in the textile industry, gripper looms are the most well-known and widely spread. This is because, in addition to excellent weft transportation accuracy and good weaving speed, they provide high versatility in production using multiple types of yarns.

[0003] As is well known to those skilled in the art, the weft insertion system in a gripper loom consists of two grippers that transport the weft through a reed formed between the warp threads. The transfer gripper catches the weft coming from a weft supply device on one side of the loom and transports it to the center between the reeds. There, it meets the withdrawal gripper that starts moving simultaneously from the opposite side of the loom. The withdrawal gripper receives the weft from the transfer gripper and pulls it out to the exit between the reeds. As the gripper moves back to the position where it changes direction, i.e., outside the reed, the gripper comes into lateral contact with the corresponding gripper opener. As a result, the gripper opener applies pressure to a lever or cursor that partially protrudes from the side surface of the gripper, opening the weft gripping means provided on the gripper.

[0004] Therefore, the gripper opener is a static element positioned outside the reed, along the gripper path. The properly shaped contact edge of the gripper opener is intended to progressively interfere with the lever or cursor to allow opening the gripper's gripping means for picking up the weft, releasing it at the end of the insertion step, or simply removing any weft residue that may have remained in the gripping means. Thus, opening the gripper is achieved by high-speed mutual sliding between the gripper lever or cursor and the gripper opener edge, which is repeated hundreds of times per minute. Considering these continuous friction conditions, and to prevent the rapid deterioration of the gripper, which is an expensive and delicate component, the gripper opener is made of a material significantly softer than the metal lever or cursor and is inevitably subjected to high wear, requiring periodic replacement.

[0005] However, visually checking the wear of gripper openers is not easy, and currently, time-based replacement is employed. This method inevitably carries the risk of discarding still-functioning grippers or weaving with gripper openers that are already excessively worn, potentially leading to increased errors in weft insertion and deterioration of the grippers themselves.

[0006] Therefore, it is clear how useful a device that can automatically monitor the maximum permissible wear limit of the gripper opener would be. This monitoring device would allow weavers to replace the gripper opener at the most appropriate time—before the quality of the fabric is compromised, before the gripper deteriorates, and before the wearable thickness of the contact edge of the gripper opener is completely worn out.

[0007] Therefore, the technical problem addressed by the present invention is to provide a gripper opener wear monitoring device that can operate without interrupting the operation of a loom in areas where the equipment is already densely concentrated, and thus where the available remaining space is extremely limited. This monitoring device must also take into account the fact that wear detection sensors cannot be installed on the contact edge of the gripper opener because the contact edge is in continuous physical contact with the gripper.

[0008] In addressing this technical challenge, the first objective of the present invention is to provide a low-volume gripper opener wear monitoring device.

[0009] A second object of the present invention is to provide a wear monitoring device that does not require assembly and disassembly of the device itself when gripper openers are frequently replaced.

[0010] Finally, a third object of the present invention is to provide a gripper opener wear monitoring device that does not require sensors or other fixed elements positioned in front of the contact edge of the gripper opener. [Overview of the project]

[0011] This problem is solved by a loom including a gripper opener wear monitoring device having the features defined in claim 1, and these objectives are achieved. Other preferred features of such a gripper opener wear monitoring device are defined in the dependent claims. [Brief explanation of the drawing]

[0012] Further features and advantages of a loom including a gripper opener wear monitoring device according to the present invention will become apparent from the detailed description of preferred embodiments shown in the accompanying drawings, as non-limiting examples.

[0013] [Figure 1] This is a plan view of the pull gripper in a gripper loom. [Figure 2]This is a perspective view of a gripper opener equipped with a wear sensor for monitoring devices according to the present invention. [Figure 3] Figure 2 is a plan view of the gripper opener. [Figure 4] This is an enlarged perspective view of one of the wear sensors of the monitoring device according to the present invention. [Figure 5] This is an electrical circuit diagram that constitutes a part of the monitoring device according to the present invention. [Figure 6] This is a perspective view of a gripper opener incorporating a monitoring device according to the present invention, which is installed in a predetermined position and allows the gripper to pass in front of the gripper opener. [Modes for carrying out the invention]

[0014] To solve the above-mentioned problems with a structurally simple, compact, and easily applicable solution, the applicant has conceived of inserting at least one wear sensor, consisting of a conductive element and an associated power supply circuit, inside a gripper opener. Under standard conditions, the wear sensor is insulated by the plastic material of the gripper opener itself, so the electrical circuit is open. The aforementioned electrical circuit actually consists of a power supply unit including a power source that applies voltage to the wear sensor, and a closed circuit unit that is electrically connected to the power supply unit only when wear progresses on the contact edge of the gripper opener and the wear sensor is exposed and comes into contact with the closed circuit unit of the electrical circuit. By detecting the current flowing through the electrical circuit in this way, a signal can be obtained that directly and reliably indicates that the gripper opener has reached its wear limit.

[0015] According to an important feature of the present invention, in order to reduce the complexity and volume of the control device of the present invention and to avoid the need to disassemble and reassemble the control device or at least a part of it each time the gripper opener is replaced / reversed, the closed circuit portion of the aforementioned electrical circuit is advantageously formed by a non-wired electrical circuit including conductive loom components that are normally already present on the loom.

[0016] More specifically, the present invention will be described with reference to the negative pull-out gripper 10 shown in Figure 1. Those skilled in the art will naturally have no difficulty applying a similar inventive principle to a positive pull-out gripper or a conveyor gripper.

[0017] The pull-out gripper 10 consists of a body 11 with a hook 12 at its front end for catching the weft thread. The weft thread is held in place by a spring mechanism (not shown) elastically pressed against the hook 12, sandwiched between the inner wall of the hook 12 and the tip of a rod 13 that is axially movable inside the gripper 10. Figure 1 also shows a cursor 14 that protrudes laterally from the body 11 of the gripper 10. When this cursor 14 is gradually pressed by the contact edge 3 of the gripper opener 1, it moves the rod 13 against the spring mechanism and releases it after the weft thread has been fully inserted into the opening.

[0018] Figures 2 and 3 schematically show a gripper opener 1 on which part of the wear monitoring device for the gripper opener according to the present invention is installed. The gripper opener 1 is composed of appropriately shaped plastic material profiles, and its outer layer is formed of a material having a low coefficient of friction, such as polyester resin. This material exhibits lower wear resistance than the metal material on which the cursor 14 of the pull-out gripper is formed. These requirements are necessary, on the one hand, to minimize the frictional force generated when the cursor 14 of the pull-out gripper slides over the gripper opener 1, and on the other hand, to ensure that the generated frictional force causes wear exclusively on the gripper opener 1 without damaging the metal cursor 14 of the pull-out gripper.

[0019] The gripper opener 1 is fixed in accordance with the pull-out gripper guide and secured by a fixing means housed in a through-hole 2 formed in the gripper opener. This allows the opposing cursor 14 to slide against the contact edge 3 of the gripper opener 1 as the pull-out gripper passes in front of the gripper opener 1. The contact edge 3 of the gripper opener 1 is formed with a shape that is slightly inclined with respect to the forward direction of travel of the pull-out gripper 10. This generates the desired progressive pressure on the operating cursor 14 as the pull-out gripper 10 travels in front of the gripper opener 1, thereby operating the movable rod 13 of the pull-out gripper 10. As is well known, both sides of each gripper opener 1 are symmetrical in order to extend the service life of each individual gripper opener 1. This allows the gripper opener 1 to continue functioning with the undamaged contact edge 3 on the opposite side if the contact edge 3 of the gripper opener becomes completely worn out, by disassembling it, rotating it 180° on the same plane, and reassembling it in the operating position.

[0020] Referring again to Figures 2 and 3, it can be seen that a key feature of the present invention is that two wear sensors 4 are inserted inside the gripper opener 1. This operation will be described later. The wear sensors 4 have a preferred shape as shown in the enlarged detail view of Figure 4, and a conductive material, particularly a copper alloy, is preferably used. Each wear sensor 4 includes a plate 5 which preferably has a triangular shape with rounded corners, with an electrical connection hole 6 formed at one vertex and two contact pins 7 protruding from the opposite two vertices. The two contact pins 7 have a cylindrical or at least rounded shape toward the outside of the plate 5 and are designed to contact the cursor 14 of the gripper shown when the wear of the contact edge 3 of the gripper opener 1 reaches its limit. Figures 2 and 3 clearly show how the two wear sensors 4 are embedded in appropriately staggered and opposing positions near the center of the gripper opener 1. As a result, the two contact pins 7 of each wear sensor 4 extend parallel to the corresponding contact edge 3 of the gripper opener, while maintaining a distance corresponding to the maximum allowable wear thickness of the gripper opener 1.

[0021] Figure 5 shows the electrical circuit 100 of the wear monitoring device for the gripper opener 1 according to the present invention. The power supply section of the electrical circuit 100 includes a power supply 102, a resistor 103, and a wear sensor 4 for the gripper opener 1, all connected in series by conventional wiring. Furthermore, a voltmeter 104 allows monitoring of the temporal fluctuation of the potential difference across the resistor 103. The closed circuit section of the electrical circuit 100 is instead an unwired, incomplete circuit consisting of the conductive components of the loom itself, specifically the gripper strap guide group 106, the gripper strap 107, and finally the pull-out gripper 10, particularly its outer cursor 14. It should be noted that all elements constituting the closed circuit section of the electrical circuit 100 are made of metal materials such as the guide group 106 and the transport gripper 10, or carbon fiber such as the gripper strap 107, and therefore have sufficient conductivity. The closed-circuit section of this electrical circuit allows the electrical circuit 100 to be closed without the need to install any dedicated wiring when the contact edge 3 of the gripper is completely worn and the wear sensor 4 makes direct contact with the cursor 14 of the pull-out gripper 10, thus greatly simplifying the configuration of the control device. Finally, both ends of the electrical circuit 100 are connected to a common equipotential reference 101, which may be the same loom metal structure.

[0022] In the normal state, the power supply part and the closed circuit part of the electric circuit 100 are separated and insulated from each other by the contact edge 3 of the gripper opener 1. This contact edge 3 separates the wear sensor 4, particularly its contact pin 7, from the cursor 14 of the gripper 10. The thickness of the contact edge 3 covering the contact pin 7 is defined when machining the recess for accommodating the wear sensor 4 and corresponds to the maximum allowable wear of the gripper opener 1. This maximum wear thickness is, for example, 1 mm. Under normal wear conditions, since the wear sensor 4 is covered by the contact edge 3 of the gripper opener 1, it is not in electrical contact with the cursor 14 of the gripper 10. On the other hand, when the entire thickness of the contact edge 3 covering the contact pin 7 wears due to friction with the cursor 14, the wear sensor 4 is exposed on the surface of the gripper opener 1. Thereby, it comes into electrical contact with the cursor 14 of the gripper 10, and the electric circuit 100 becomes a closed circuit. When the electric circuit 100 becomes a closed circuit, a current flows in the electric circuit 100, and a potential difference occurs across both ends of the resistor 103. This potential difference is detected by the voltmeter 104. For this purpose, other current detectors can of course be used.

[0023] Furthermore, the electric circuit 100 is connected to visual and / or audible alarm means by a method well-known in the prior art to prompt the operator to replace / rotate the gripper opener 1. Alternatively, it is also possible to directly transmit a signal that the electric circuit 100 is closed to the control unit of the loom before excessive wear of the gripper opener 1 causes non-uniformity and irregularity in the fabric being processed, and start the program stop of the weaving process.

[0024] From the above description, it is clear that the wear monitoring device for the gripper opener of the gripper loom according to the present invention fully achieves all intended purposes. Considering that the closed circuit part is composed of the conductive elements of the loom itself, such a device is composed of an electric circuit having a substantially minimum volume and is partially incorporated within the thickness of the gripper opener 1.

[0025] The electrical connection between the wear sensor 4 and the electrical circuit can be easily and effectively achieved through a static contact consisting of a conductive pin integrally formed on the sheet portion of the gripper opener and electrically connected to the power supply portion of the electrical circuit 100. When the gripper opener 1 is fixed at the normal working position, this conductive pin automatically fits into the hole 6 of the wear sensor 4. Therefore, no additional assembly / disassembly work beyond the known assembly operation of assembling the gripper opener 1 to its sheet portion is required to obtain the electrical connection between the wear sensor 4 and the electrical circuit 100.

[0026] Finally, since the wear sensor is accurately positioned inside the gripper opener 1 itself, the monitoring device of the present invention does not include elements arranged in front of the gripper opener. Therefore, no obstacles or additional friction will occur in the path of the gripper due to the monitoring device.

[0027] However, the present invention should not be limited to the specific configurations described above, which are merely examples. It should be understood that various modifications can be made without departing from the protection scope of the present invention defined only by the following claims within the technical scope of those skilled in the art.

Claims

1. A gripper loom equipped with a wear monitoring device for the gripper opener (1), wherein the gripper opener (1) releases the gripping means (13) of the loom's gripper (10) when the gripper (10) slides against the contact edge (3) of the gripper opener (1) with the cursor (14), The gripper loom is characterized in that the monitoring device includes at least one conductive wear sensor (4) embedded in the body of the gripper opener (1) at a predetermined distance from the contact edge (3), the distance defining the maximum wear thickness of the contact edge (3); the electrical circuit (100) includes a power supply unit that supplies voltage to the wear sensor (4) and a non-wired closed circuit unit that includes conductive components of the loom; and the current detector indicates that current has flowed to the electrical circuit (100) when the maximum wear thickness of the contact edge (3) has completely worn down and the wear sensor (4) has come into contact with the cursor (14) of the gripper (10).

2. A gripper loom equipped with a wear monitoring device for a gripper opener (1) according to claim 1, wherein the power supply unit and the closed circuit unit of the electrical circuit (100) are separated from each other by the maximum wear thickness of the contact edge (3), and their ends are connected to the same equipotential reference (101).

3. The gripper loom is equipped with a wear monitoring device for a gripper opener (1) according to claim 2, wherein the power supply unit of the electrical circuit (100) comprises a power supply (102), a resistor (103), and the wear sensor (4) of the gripper opener (1), all connected in series.

4. The closed circuit portion of the electrical circuit (100) comprises a non-wired electrical circuit including a group of gripper strap guides (106), a gripper strap (107), a gripper (10), and a cursor (14) for the gripper, all of which are made of a conductive material, and is equipped with a wear monitoring device for a gripper opener (1) according to claim 2.

5. The gripper loom is equipped with a wear monitoring device for the gripper opener (1) according to claim 2, wherein the equipotential reference (101) is a metal structure of the loom.

6. A gripper loom equipped with a wear monitoring device for a gripper opener (1) according to claim 1, wherein the wear sensor (4) includes one or more contact pins (7) that extend parallel to each contact edge (3) of the gripper opener (1) and are spaced apart from there by a distance corresponding to the maximum wear thickness of the contact edge (3).

7. The gripper loom is equipped with a wear monitoring device for a gripper opener (1) according to claim 6, wherein the wear sensor (4) includes a plate (5) integrally formed with the contact pin (7) and an electrical connection contact (6) of the electrical circuit (100) to the first power supply unit.

8. A gripper loom equipped with a wear monitoring device for a gripper opener (1) according to claim 7, wherein the plate (5) has the shape of an equilateral triangle with rounded corners, the electrical connection contact (6) is provided at one of its vertices, and the contact pin (7) protrudes from the opposite vertex.

9. The gripper loom equipped with a wear monitoring device for a gripper opener (1) according to claim 8, wherein the electrical connection contact (6) is a hole that can engage with a conductive pin integrally formed on the sheet portion of the gripper opener (1) and is electrically connected to the power supply portion of the electrical circuit (100).

10. A gripper loom equipped with a wear monitoring device for a gripper opener (1) according to any one of claims 1 to 9, the monitoring device comprising two wear sensors (4) provided on two opposing contact edges (3) of the gripper opener (1).

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