Weft feeder for loom equipped with independent optical unit integrated into electromagnet group controlling weft release

Abstract

To provide a novel weft feeder for a loom, especially for air-jet and water-jet looms, which is equipped with an independent optical unit that is integrated into an electromagnet group of the weft feeder for controlling release of the weft in the loom.SOLUTION: A weft feeder for a loom comprises: a winding group (W) for winding a weft yarn on a weft feeder drum (D); an optical unit (P) comprising one or more optical sensors for monitoring the weft yarn wound on the drum (D) and the release of the weft yarn from the drum (D); an electromagnet group (E) controlling the movement of a stop pin (15) for preventing the release of the weft yarn from the drum (D) and enclosed within a cup-shaped shell (11) from which the stop pin protrudes so as to interfere with the drum (D); and a weft feeder processing board for controlling the logical function of the weft feeder.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a new weft feeding device for weaving machines, in particular for air jet and water jet weaving machines, which, in addition to the usual functions already provided by known weft feeding devices for weaving machines currently available, comprises an independent optical unit integrated into the electromagnet group of the weft feeding device which controls the weaving separation of the loom. [Background technology]

[0002] As is known, a weft feeder is a weft thread supplying device located between the loom and the bobbins. It supplies the weft thread to the loom by continuously winding it onto a cylindrical drum - clockwise or counterclockwise, depending on the characteristics of the thread, at a speed as constant as possible - to produce a reserve of weft thread that is then removed from the drum axially at a variable speed during the weft insertion operation in the storehouse, so as to avoid tension peaks in the weft thread, which would impair the strength of the thread itself and the quality of the woven fabric.

[0003] The weft feeder is a device that has been used in textile mills for many years. During its evolution, in addition to the basic functions mentioned above, additional control functions have been added to ensure the continuous presence of the weft yarn at certain critical points in the weft feeder: regulating the amount of weft yarn accumulation and, if necessary, adjusting the distance between the individual coils; slowing down the weft yarn discharge speed to counteract the dynamic effects of sudden withdrawal accelerations; measuring the length of the weft yarn portion withdrawn by the insertion device; and finally, controlling the release of the weft yarn for insertion in the warp store at a preset length.

[0004] To properly perform the above functions, the weft yarn supplying device (FIG. 1) comprises an optical unit P and an electromagnet group E (hereinafter also referred to as "ELM group") mounted on the base body C of the weft yarn supplying device. The optical unit P includes one or more optical sensors and serves to monitor the winding of the weft yarn onto the drum D by the winding group W integrated with the hollow shaft A of the weft yarn supplying device through feedback control of the weft yarn supplying device's motor. The optical unit P therefore controls the winding of new weft coils onto the drum D and also counts the number of coils released from the drum D to the weft insertion device. The electromagnet group E controls the linear movement of a stop pin 15 between an advanced position and a retracted position. In the advanced position, the free end of the stop pin is inserted into a corresponding position on the fabric supplying device drum D, thereby preventing the weft yarn from being released from the drum. In the retracted position, the desired number of weft coils are instead released. By the action of the electromagnets E, the weft thread is actually drawn from the loom in a predefined number of coils, which number is counted by the optical unit P.

[0005] A single optical unit contains multiple optical sensors with different functions, specifically: - Input optical sensor T: For each rotation of the weft yarn supply winding group W, it checks whether the weft yarn is properly wound onto the drum and detects any breaks in the weft yarn. - two exit optical sensors S and Z, corresponding to the two rotation directions in which the yarn is wound onto the drum D by the winding group W, for detecting the yarn exiting the drum, counting the number of coils withdrawn from the loom and determining the corresponding length of withdrawn yarn; - Pre-check optical sensor R: A sensor that detects the presence of coils at a preset height on the drum, thus maintaining a constant maximum number of coils stored on the drum.

[0006] The number of optical sensors in each optical unit depends on the type of function it has and therefore affects the cost of the weft feeder. The basic optical unit has the smallest configuration suitable for the simplest operation and uses only two sensors: the inlet sensor T and the outlet sensor S. On the other hand, the optical unit with the most advanced technology is equipped with all four optical sensors described above: in addition to the T and S sensors, it also has a second outlet sensor Z and a preliminary verification optical sensor R.

[0007] Considering convenience and ease of assembly and connection, the optical unit P is usually assembled together with the electromagnet group E. However, this assembly of the optical unit and the ELM group together has so far adopted two substantially different embodiments. In the first embodiment, the optical unit P is in fact freestanding and is mounted outside the electromagnet group E. On the other hand, in the second embodiment, the optical unit P is mounted inside the electromagnet group E, i.e., enclosed in the same metal cup-shaped shell 11 that houses the ELM group, and is mechanically and electrically connected to the ELM group.

[0008] In the first embodiment, the electromagnet group E is provided with suitable locations for assembling and passing the cables of each optical sensor. These locations are located in appropriate areas on the external surface of the cup-shaped shell 11 of the ELM group, corresponding to the specific verification function of each optical sensor. In this first solution, the optical sensors are typically constructed using traditional electronic components (so-called "through-hole" soldered manually and then encapsulated in a resin block). The advantage of this first embodiment is that the optical units are completely independent of the ELM group, making the associated maintenance, testing, and replacement simple, fast, and economical. Furthermore, during production, these optical units can be tested individually before assembly into the ELM group. However, despite these advantages, the first example described above has the disadvantage that the components used are large, requiring sufficient space for their installation and the associated wiring. Therefore, it is very difficult to manufacture a weft feeder equipped with all four types of optical sensors described above. Therefore, this technical solution is usually limited to weft feeders equipped only with the basic optical sensors T and S. Furthermore, mounting the optical unit on the outer surface of the cup-shaped shell 11 surrounding the ELMs creates a textile drawback, as the optical unit disrupts the uniformity of the outer surface of the cup-shaped shell of the ELMs, significantly increasing the likelihood of the weft yarn becoming tangled in the weft feeder when it is released from the weft feeder.

[0009] In a second embodiment, the optical unit P is made up of miniaturized electronic components suitable for automated surface mounting technology (SMT) on a printed circuit board (PCB). Appropriate diaphragms and optical screens are added to the PCB, which is then fixed, encapsulated, and sealed in the cup-shaped shell 11 of the ELM group. The advantage of this second solution is, first of all, that all components of the optical unit P and the electromagnet group E are enclosed in the same cup-shaped shell 11. This makes the external surface of the shell 11 cleaner and more uniform, improving the operation of the weft feeder from a textile engineering perspective. Furthermore, the use of miniaturized components on the PCB and its insertion into the cup-shaped shell 11 makes it possible to implement the four types of optical sensors described above (not only T and S, but also R and Z) through suitable windows in the cup-shaped shell 11 at appropriate positions, without a significant increase in costs. The only drawback of this second solution, which is completely opposite to the only advantage of the first solution, is that, since the optical unit P is permanently integrated into the cup-shaped shell and interconnected with the other members of the ELM group, each member cannot be tested separately during manufacture, and if one of the optical sensors fails during use, the entire package including the optical unit P must be replaced. The entire package including the electromagnet group E and the associated protective metal cup-shaped shell 11 must be replaced, which has a significant impact on maintenance or replacement costs. EP-3620561 (in the name of the same applicant) discloses a weft yarn feeding device with an optical unit manufactured according to the above-mentioned second embodiment. Summary of the Invention [Problem to be solved by the invention]

[0010] The technical problem solved by the present invention is to produce a yarn feeding device that combines the advantages of both currently known optical unit configurations without the associated disadvantages: the optical unit is located in the same cup-shaped shell that houses the electromagnets, and is designed so that it can be independently tested during manufacture, and can be maintained and possibly replaced without having to retract the electromagnets.

[0011] In the context of this technical problem, a first object of the present invention is to provide a completely self-contained optical unit that can be housed in the same cup-shaped housing shell as the electromagnet group in an independent and easily removable manner.

[0012] A second object of the present invention is to reduce the number of wires coming out of the optical unit to one, instead of two or more as in conventional methods.

[0013] Finally, a third object of the present invention is to produce an optical unit that can optionally incorporate any or all of the four optical sensors in a single design without modifying the optical unit's structure, in order to expedite manufacturing, testing, maintenance, and replacement operations. [Means for solving the problem]

[0014] This problem is solved and these objects are achieved by a weft yarn feeding device for a loom, which integrates an independent optical unit with a group of electromagnets controlling the release of the weft yarn, and which has the features defined in independent claim 1. Further preferred features of such a weft yarn feeding device are defined in the dependent claims. [Brief explanation of the drawings]

[0015] Further detailed features and advantages of the weft yarn feeding device according to the invention, integrating an independent optical unit with the electromagnet group controlling the release of the weft yarn, will become more apparent from the following detailed description of a preferred embodiment, given by way of limiting example only and illustrated in the accompanying drawings, in which: [Figure 1] 1 is an axial section through a weft yarn supplying device with an independent optical unit according to the invention; [Figure 2] FIG. 1 is a perspective view of a free-standing optical unit prior to assembly into a cup-shaped shell housing the ELMs. [Figure 3] FIG. 3 is an exploded view of the optical unit of FIG. 2. [Figure 4] 3 is a plan view of the optical unit of FIG. 2 assembled and fixed to a cup-shaped shell that houses an ELM group. [Figure 5] 5 is a cross-sectional view of the optical unit of FIG. 2 taken along line VV of FIG. 4. [Figure 6] FIG. 6 is a bottom perspective view of a cup-shaped shell that houses the ELM group and the optical unit shown in FIGS. DETAILED DESCRIPTION OF THE INVENTION

[0016] According to the present invention, the above-mentioned problems are solved by a structurally innovative solution that allows for quick and easy assembly, testing, maintenance, and replacement. The independent optical unit consists of a rigid-flex printed circuit board housed in a closed, sealed protective box, from which only the wiring emerges for connection to the main weft feeder processing board, which controls the logic functions of the weft feeder. The protective box is sized and shaped so that it can be stably housed and fixed by removable fastening means to the bottom wall of the cup-shaped shell surrounding the electromagnet group E. Other accessories necessary for the correct operation of the optical sensor for detecting the weft yarn are also pre-printed or pre-inserted into the protective box. This makes the optical unit P of the present invention a completely self-contained group, without any permanent mechanical or electrical connections between the ELM group and the cup-shaped shell surrounding it. Therefore, it can be quickly and easily removed by simply disconnecting the end plugs of the wiring from the weft feeder processing board, freeing the wiring from the existing cable glands, and then loosening the aforementioned removable fastening means.

[0017] The innovative structure of the optical unit P of the present invention is clearly shown in FIG. 2 and explained in detail in the exploded view of FIG. 3 and the cross-sectional views of FIG. 4 and FIG. 5. Thus, the optical unit P includes a protective housing 1, which defines its external dimensions. It consists of a lower half housing 1a and an upper half housing 1b, which are interconnected by a suitable coupling and closure system, ensuring a complete dust-proof and waterproof seal. The protective housing 1 is manufactured by molding a plastic material and houses all components contributing to the operation of the optical unit P. The lower half housing 1a houses a rigid-flex PCB 2, to which four pairs of light-emitting and light-receiving elements 3 are soldered (indicated in the drawing by reference number 3, with a letter index (T, S, Z, R) corresponding to the type of sensor). The diaphragm 4d and the optical channel 4c supporting the optical elements 3, which are necessary for the selection and blocking of the light beam, are shown in detail in FIG. 5. They are formed by molding, preferably in the same molding process as the protective housing 1, and therefore form part of the protective housing 1. The optical sensor of the optical unit P of the present invention, whether intended for control type T, S, Z or R, comprises a pair of light-emitting and light-receiving elements 3, a corresponding optical channel 4c and diaphragm 4d, and a foam light-blocking element 5 preventing the light radiation from diffusing in unwanted directions. The specific construction and operational details of said optical sensor (characterized by SMD-type optical elements 3 whose optical axes are arranged parallel to each other and perpendicular to the PCB surface 2) are disclosed in detail in the previously published patent EP-3620561 in the name of the same applicant, the contents of which are hereby fully cited solely for the purpose of understanding the correct operation of said optical sensor, which operation, however, does not form part of the present invention.

[0018] The use of a rigid-flex PCB 2 (i.e. a PCB consisting of flat, rigid sections of the traditional type, connected mechanically and elastically with other sections connected by highly flexible sections) makes it easy to manage different inclinations between S-, Z- and R-type optical sensors (all located in the same horizontal plane) and T-type optical sensors, which are instead located on a plane strongly inclined relative to said common horizontal plane. The PCB 2 actually has two independent rigid sections with different angular orientations, each with the optical element 3 of the corresponding optical sensor soldered to it. These rigid sections are connected by a flexible section 2f containing copper traces connecting the SMD elements mounted on the two rigid sections of the PCB 2.

[0019] Advantageously, in the optical unit P of the present invention, compared to those disclosed in the above-mentioned previous patents, the optical channel 4c and the diaphragm 4d are molded directly into the protective box 1. Specifically, the optical channel 4c is molded into the lower half box 1a, and the diaphragm 4d is molded into the upper half box 1b. This significantly simplifies both the manufacturing and assembly of the device. In fact, the same half box 1a already has a precise receiving space for the PCB 2, which is made up of several parts that cooperate to hold the PCB 2 in place. This allows the PCB 2 to be quickly inserted into the half box 1a, while ensuring the highest possible alignment of the optical component 3 with respect to the optical channel 4c and the diaphragm 4d.

[0020] Once the PCB 2 is aligned, a darkening element 5, preferably made of foam, is placed over each pair of optical components 3. The darkening elements 5 are necessary to prevent unwanted direct passage of light between the two light-emitting and light-receiving elements 3 of the same optical sensor, which could interfere with the correct operation of the sensor. Finally, the PCB 2 is electrically connected to the weft feeder processing board (not shown) that controls the logic functions of the weft feeder by appropriate wiring, such as a wiring cable 6 with two male terminal connectors, one end of which is connected to a corresponding female connector 7 integrally formed on the PCB 2 (where the entire copper wiring network of the PCB 2 converges) and the other end of which is connected to a special female connector formed on the weft feeder processing board. The wiring cable 6 exits through a hole 8 formed in the upper half box 1b, which is closed with a conventional rubber gasket 9 that elastically adheres to the edge of the hole 8 and the side of the wiring cable 6, ensuring an excellent seal against the ingress of dust and liquids into the protective box 1. The hole formed in the lower half box 1a for the passage of the optical radiation exchanged by the optical element 3 is closed and sealed in known manner by a transparent glass disc 10 (see FIGS. 5 and 6).

[0021] After the components are placed in the lower half box 1a, the distribution cable 6 is connected to the same box, and the upper half box 1b is attached and sealed with a suitable coupling and closure system to ensure a tight seal against dust and liquids, thereby forming the optical unit P of the invention. At this point, the protective box 1 is placed in a metallic cup-shaped shell 11, which houses the electromagnet group E and is fixed to the cup-shaped shell itself by removable fastening means 13 (e.g., screws or press studs) housed in through-holes 14 in the upper half box 1b. In accordance with known methods, the cup-shaped shell 11 is made up of one or more components and is closed by a lid 12 with a sealing gasket on top. To facilitate and speed up the assembly of the protective box 1 into the cup-shaped shell 11, its external features, such as shape and size, are designed to allow for a specially adapted assembly within the cup-shaped shell 11. On the other hand, the glass discs 10 partially protruding from the bottom of the lower half box 1a are placed in corresponding holes formed in a cup-shaped shell 11, as shown in FIG. 5 (see FIG. 6).

[0022] From the above description, it is clear that the weft feeding device of the present invention fully achieves its intended purpose. The optical unit P described above is in fact completely independent, mechanically and electrically, from the metallic cup-shaped shell 11 and the electromagnet group E in which it is housed. Therefore, if a cable gland is arranged along the path of the distribution cable 6, the optical unit P can be quickly removed as a whole by simply loosening the removable fastening means 13 and disconnecting the distribution cable 6 from the weft feeding device processing board. Furthermore, since the arrangement and wiring of the individual optical sensors 3 are completely independent from each other, the optical unit P can be equipped with any number and type of optical sensors 3 depending on the weft feeding device in question and its intended use, without requiring any design changes.

[0023] However, it should be understood that the present invention is not limited to the specific configurations shown above, which are merely examples. Various modifications are possible within the level of skill of those skilled in the art, and do not depart from the scope of protection of the present invention. The scope of protection of the present invention is defined only by the following claims. [Explanation of symbols]

[0024] A hollow shaft C Base body Drums E Electromagnets (or ELMs) P Optical Unit R Preliminary confirmation optical sensor S Exit optical sensor indicator T entrance optical sensor W Winding group Z exit optical sensor index 1 protective box 1a Lower half box 1b Upper half box 2 Rigid-Flex PCB 2f Flexible part of PCB2 3 Optical Components 4c Optical Channel 4d diaphragm 5 Darkening material 6 Wiring cable 7 female connectors 8 Cable 6 storage hole 9 Rubber Gasket 10. Glass 11 Cup-shaped shell 12 Lid of cup-shaped shell body 11 13 Removable fastening means 14 Hole for fixing means 13 15 Weft stop pin

Claims

1. A weft supplying device for a loom, a winding group for winding a weft yarn around a weft supplying device drum; an optical unit having one or more optical sensors for monitoring the weft yarn being wound around the drum and the weft yarn being separated from the drum; an electromagnet group enclosed within a cup-shaped shell-like body that controls the movement of a stop pin that prevents the weft yarn from being separated from the drum and that protrudes so that the stop pin interferes with the drum; and a weft supplying device processing board that controls the logic functions of the weft supplying device, a protective box housed inside the cup-shaped shell body and removably fixed thereto; and a weft supplying device for a loom, characterized in that the optical unit is housed in a protective box and is electrically connected to the weft supplying device processing board by direct wiring.

2. 2. A weft supplying device for a loom according to claim 1, wherein the function of said optical unit is independent and autonomous with respect to the function of said group of electromagnets enclosed inside said cup-shaped shell.

3. 2. A weft supplying device for a loom according to claim 1, wherein the protective box comprises an upper half box and a lower half box joined together.

4. 4. A weft supplying device for a loom according to claim 3, wherein the protective box is sealed to prevent the intrusion of dust and liquid.

5. 2. A weft supplying device for a loom according to claim 1, wherein the optical unit has a printed circuit board to which the light emitting and light receiving elements of the optical sensor are soldered.

6. 6. A weft supplying device for a loom according to claim 5, wherein the printed circuit board is a rigid-flex printed circuit board including two rigid sections to which the light emitting and light receiving elements are soldered.

7. 7. A weft supplying device for a loom according to claim 5 or 6, further comprising a darkening member made of foam material arranged on said light emitting and receiving elements.

8. 7. A weft yarn supplying device for a loom according to claim 6, wherein the two rigid parts of the printed circuit board have different inclinations and are connected by a flexible part of the printed circuit board containing copper wires therein interconnecting components mounted on the two rigid parts.

9. 6. A weft supplying device for a loom according to claim 5, wherein the wiring comprises a wiring cable electrically connected to the printed circuit board and the weft supplying device processing board via a plug connection.

10. 10. A weft supplying device for a loom according to claim 9, further comprising a rubber gasket for sealing an outlet hole for said distribution cable exiting said protective box.

11. 4. A weft supplying device for a loom according to claim 3, further comprising an optical channel and a diaphragm of said optical sensor formed integrally with said protective box.

12. 12. A weft supplying device for a loom according to claim 11, wherein the optical channel and the diaphragm are formed in the lower half box and the upper half box, respectively.

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