Joint head and device for joining textile yarns by compressed air

Abstract

A joining head (10) and a device (100) for joining textile yarns by compressed air, the joining head comprising: a body (11) in which a longitudinally extending joining chamber (12) is formed, the joining chamber being open at two opposite ends (12a, 12b), being provided at the top with a longitudinal cutout (13) for introducing the yarn or thread to be joined, having an intermediate longitudinal plane (PL) along at least one longitudinal section, at least one injection duct, the injection duct being arranged in the joining chamber (12), and an injection duct for injecting compressed air into the joint chamber, the injection duct consisting of a cylindrical bore in the main body and at openings of two opposite ends, a first end of the bore opening into the joint chamber forming a nozzle for injecting a compressed air flow, a second end of the bore opening into a seat formed in the main body forming a mouth for the compressed air flow to enter, a ratio (Pd) of a generatrix length of the bore having a minimum length (Lmin) to a maximum lateral dimension (Dmax) of the nozzle is greater than or equal to 2.8. According to the utility model, the mechanical strength, the aesthetic quality and the repeatability of the joint are improved.

Description

Technical Field

[0001] The present disclosure relates to an improved joining head applicable to an apparatus for joining textile threads and yarns by compressed air and an apparatus for joining textile threads and yarns by compressed air comprising such a joining head. Background Art

[0002] Pneumatic joining devices for joining textile threads and yarns are already known, comprising a joining chamber provided at the top with a longitudinal cutout for introducing the threads to be joined and into which a jet of compressed air suitable for operating the seamless splicing of the threads or yarns is injected.

[0003] Initially, the threads introduced into the joining chamber from opposite sides through longitudinal cutouts and held at their ends outside the joining chamber by special locking devices are directly acted upon inside the joining chamber by at least one jet of compressed air generally ejected into the middle of the joining chamber, thereby causing the fibers to mix and interweave by the action of strong turbulence.

[0004] Then, in order to improve the interweaving and mixing of the fibers by removing the original twist of the threads, a solution was developed to generate opposing air vortices inside the joining chamber, which operated to untwist the ends of the threads for joining.

[0005] A further development is the preliminary step of pre-treating the ends of the threads to be joined, before the actual operation of joining the threads, in order to untwist the ends and thereby spread out the fibers at the ends and make them parallel.

[0006] Therefore, pneumatic splicing devices have been developed whose splicing chamber is adapted to twist, rather than untwist, the threads during the splicing operation by means of air vortices operating in the same direction as the original twist of the threads to be spliced.

[0007] However, when using this last type of joining chamber, the problem has been found that two opposing air vortices generated by the nozzles and directed into the joining chamber in close proximity can negatively influence each other.

[0008] Such problems were initially solved by solutions such as described in IT1177159 (DE3540324), in which the joining chamber is divided by a transverse central slit for air passage into two longitudinal sections, to each of which a respective nozzle for ejecting compressed air forming a respective air vortex is opened.

[0009] Furthermore, such transverse slits allow reducing the amount of air that escapes from the two opposite open ends of the joining chamber, which, if excessive, could damage the fibers of the yarn, in particular of the soft yarn or very short-staple type.

[0010] A further development consists in inserting a separating membrane into such a transverse slit, such as described, for example, in IT1239341 (US5152131). Such a separating membrane allows to improve the separation between the two longitudinal parts of the joining chamber, so as to maintain the air vortices generated therein physically separated from each other so as not to influence each other and thus stabilize the position of the thread during joining. However, this latter solution, although giving good results, shows clear limitations in terms of the range of processable threads or yarns and is difficult to manufacture due to the structural complexity.

[0011] A further development consists in separating the two air vortices by injecting a further jet of compressed air into the joining chamber at an intermediate position, such as is described, for example, in patent IT10201390213013.

[0012] However, even in this case, when changing the type of thread or yarn, a different splicing head is required, which not only involves greater design and production complexity, but also increases the risk of failure. The fact that the different splicing heads should be interchangeable increases the likelihood that the end user will adopt a splicing head that is not suitable for the type of thread or yarn to be processed, resulting in a low-quality splice.

[0013] Furthermore, for the same splicing head and thread or yarn, it has been found that over time, splices with different aesthetic and mechanical qualities can be obtained. Utility Model Content

[0014] It is an object of the present disclosure to create an improved bond head which overcomes the disadvantages of the prior art.

[0015] Within the scope of this general aim, an object is to provide a joining head that is simple in structure and construction and that allows maintaining the air vortices used to twist the thread in the original twist direction well separated from each other, increasing their stability and thus improving the mechanical strength and aesthetic quality of the joints obtainable and their repeatability.

[0016] Another object is to make a joining head that allows the joining of various threads or yarns, thereby reducing the variety of joining heads to be used with the same thread or yarn to be treated and allowing an improved connection with the joining device, making it easier and more stable.

[0017] These objects are achieved by making the improved bond head of the present disclosure.

[0018] According to one aspect of the present disclosure, there is provided a joining head, which is suitable for a device for joining textile yarns by compressed air and comprises:

[0019] - a body in which a longitudinally extending joining chamber is formed, the joining chamber being open at two opposite ends, being provided at the top with a longitudinal cutout for introducing the yarns or threads to be joined and having a median longitudinal plane along at least one longitudinal section,

[0020] - at least one injection duct for injecting compressed air into the joining chamber, the injection duct being constituted by a cylindrical hole formed in the body and opening at the two opposite ends, the first end of the cylindrical hole opening at the joining chamber, thereby forming a nozzle for injecting a compressed air flow in the joining chamber, and the second end of the cylindrical hole opening at a seat formed in the body, thereby forming an orifice for allowing the compressed air flow to enter, characterized in that the ratio of the length of the generatrix with the smallest length of the cylindrical hole to the maximum transverse dimension of the nozzle is greater than or equal to 2.8.

[0021] Preferably, the ratio is less than or equal to 15.

[0022] Preferably, the ratio is between 3 and 8.

[0023] Preferably, said ratio is equal to three.

[0024] Preferably, at least at said nozzle, said joining chamber has, in a cross section orthogonal to said longitudinal extension, a circular shape interrupted by said longitudinal cutout.

[0025] Preferably, said cylindrical bore has a longitudinal axis lying in a plane orthogonal to said longitudinal extension of said joining chamber.

[0026] Preferably, the maximum transverse dimension of the nozzle is constituted by the maximum chord subtending the maximum arc of a circle defined by the intersection of the cylindrical bore and the joining chamber on a plane orthogonal to the longitudinal extension of the joining chamber.

[0027] Preferably, the cylindrical hole has a circular cross-section.

[0028] Preferably, the longitudinal axis of the cylindrical bore forms an angle with the median longitudinal plane comprised between 0° and 65°.

[0029] Preferably, the joining head comprises at least one first injection pipe and at least one second injection pipe for injecting compressed air into the joining chamber, the at least one first injection pipe and the at least one second injection pipe lead to the joining chamber from two opposite sides relative to the middle longitudinal plane and are offset from each other relative to the longitudinal extension of the joining chamber, and the at least one first injection pipe and the at least one second injection pipe are arranged to form corresponding air vortices with opposite rotation directions in the joining chamber for twisting the yarn or thread in the direction of the original twist of the yarn or thread, wherein at least one of the first injection pipe and the second injection pipe is constituted by the cylindrical hole.

[0030] Preferably, each of the first injection conduit and the second injection conduit is constituted by the cylindrical hole.

[0031] Preferably, the seat is formed in the body at the face opposite to the longitudinal cutout and is configured to airtightly accommodate a fitting for distributing compressed air to the at least one injection pipe, wherein the seat has a substantially flat surface to which the second end of the at least one injection pipe opens.

[0032] According to another aspect of the present disclosure, a device for joining textile yarns by compressed air is provided, characterized in that it includes a main body for supporting and containing, wherein the main body for supporting and containing is used to support and contain a plurality of elements for clamping, cutting, pneumatically preparing the ends of the yarns or threads to be joined and retracting the ends of the yarns or threads to be joined into a joining chamber, and a device for actuating the elements, wherein the joining chamber is defined by the above-mentioned joining head, and the joining head is removably associated with the main body for supporting and containing.

[0033] Preferably, the invention further comprises a cover for closing the longitudinal cutout of the joining chamber, wherein the cover is associated with the main body for supporting and accommodating in a manner that the cover can be moved between an open position and a closed position of the longitudinal cutout. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The features and advantages of the improved engagement head according to the present disclosure will become more apparent from the following exemplary and non-limiting description, with reference to the accompanying drawings, in which:

[0035] Figure 1 is a perspective view of a possible splicing head for splicing threads or yarns in a Z-twist according to the present disclosure;

[0036] Figure 2 yes Figure 1 A bottom plan view of the joint head;

[0037] Figure 3 is based on Figure 2 A cross-sectional view of plane III-III;

[0038] Figure 4 yes Figure 1 A top plan view of the engagement head in FIG.

[0039] Figure 5 and Figure 6 They are Figure 1 A front view and a side view of a joint head;

[0040] Figure 7 It is installed on the joint device Figure 1 A top plan view of a bonding head;

[0041] Figure 8 is based on Figure 7 Cross-sectional view along plane VIII-VIII. DETAILED DESCRIPTION

[0042] Referring to the drawings, there is shown a joining head, generally indicated by the reference numeral 10, for joining textile threads or yarns by means of compressed air.

[0043] The joining head 10 comprises a body 11 in which is formed a longitudinally extending joining chamber 12 which is open at two axially opposite ends 12a and 12b and is provided at the top with a longitudinal cutout 13 for introducing the threads or yarns to be joined.

[0044] In the embodiment shown in the figures, the joining chamber 12 has a circular cross section interrupted at the top by a longitudinal cutout 13 and which is advantageously, but not necessarily, constant along its entire length, except for the possible presence of transverse slits as described below.

[0045] However, alternative embodiments are not excluded in which the joining chamber 12 may have a cross-section of a different shape, such as for example a substantially U-shape or V-shape.

[0046] Advantageously, the opposite ends 12a, 12b of the joining chamber 12 are flared outwardly.

[0047] Furthermore, the joining chamber 12 has, in at least one section of its longitudinal extension, a central longitudinal plane and a central transverse plane. Figure 3 and Figure 4 The middle is marked by trace PL and the median transverse plane is marked by trace PT.

[0048] The median longitudinal plane PL and the median transverse plane PT are orthogonal to each other and intersect along an intersection line indicated by the trace LI.

[0049] Advantageously, the median longitudinal plane PL and the median transverse plane PT are planes of symmetry and define four quadrants in the volume inside the joining chamber 12 .

[0050] The longitudinal cutout 13 is laterally delimited by two lips 14a, 14b of the body 11. The upper surfaces of the two lips 14a, 14b, ie their outwardly facing surfaces, are flat and define a support plane for a possible cover for temporarily closing the joining chamber 12 described below.

[0051] The joining head 10 further comprises at least one duct 15 , 16 for injecting compressed air into the joining chamber 12 .

[0052] The at least one injection duct 15, 16 comprises a cylindrical hole formed in the body 11 and open at two opposite ends, a first end 15a, 16a of the cylindrical hole leads to the joining chamber 12, thereby forming a nozzle for injecting a compressed air flow therein, and a second end 15b, 16b of the cylindrical hole leads to a seat 17 formed in the body 11, thereby forming an inlet for allowing the compressed air flow to enter.

[0053] The cylindrical hole forming said at least one injection duct 15 , 16 has a circular shape in section along a plane orthogonal to its longitudinal axis 150 , 160 , preferably constant along its length.

[0054] The nozzle formed by the first end 15a, 16a is defined by the intersection curve between the cylindrical bore forming the injection duct 15, 16 and the joining chamber 12, ie the side wall of the joining chamber.

[0055] According to the present disclosure, a ratio Pd of the length of a generatrix of the cylindrical hole having a minimum length Lmin to a maximum transverse dimension Dmax of the nozzle is greater than or equal to 2.8.

[0056] Advantageously, the ratio Pd is lower than or equal to 15:

[0057] 2.8≤Pd(=Lmin / Dmax)≤15.

[0058] More advantageously, the ratio Pd is between 3 and 8:

[0059] 3≤Pd≤8.

[0060] In a preferred embodiment, the ratio Pd is equal to 3.

[0061] In fact, it has surprisingly been found that with the values ​​of the ratio Pd indicated above, it is possible to reduce the range of types of jointing heads in the case of the same thread or yarn to be joined. Thus, for example, it has been found that a jointing head with a Pd value between 2.8 and 15 can be used to carry out the joining of threads or yarns of the cotton, elastic, viscous, tencel and polyester types (with a wide range of counts), which previously required the use of different jointing heads.

[0062] Furthermore, it has surprisingly been found that, with the values ​​of the ratio Pd indicated above, the turbulent zones that can be generated in the joining chamber 12 are reduced, thereby delaying the transition of the vortex air motion from the helical laminar motion to the helical turbulent motion, delaying the formation of zones where the air flows discharged from the injection ducts 15, 16 mix. This results in an increase in the mechanical strength and aesthetic quality of the joint that can be obtained.

[0063] In the preferred embodiment as shown in the accompanying drawings:

[0064] - at least at the nozzle formed by the first end 15a, 16a of said at least one injection duct 15, 16, the joining chamber 12 has, in a section orthogonal to its longitudinal extension, a circular shape interrupted by the cutout 13 and preferably constant; and

[0065] The cylindrical bore forming the at least one injection duct 15 , 16 has a longitudinal axis 150 , 160 in a plane orthogonal to the longitudinal extension of the joining chamber 12 .

[0066] In this case, if Figure 3 As shown, the maximum transverse dimension Dmax of the nozzle formed by the first end 15a, 16a of the at least one injection pipe 15, 16 is constituted by the maximum chord AB, which is opposite to the maximum arc determined by the intersection of the cylindrical hole and the joining chamber 12 on a plane orthogonal to the longitudinal extension of the joining chamber 12 itself.

[0067] The longitudinal axes 150, 160 form an angle α with the median longitudinal plane PL, such as Figure 3 As shown, the angle is between 0° and 65°.

[0068] In a preferred embodiment, the joining head 10 includes at least one first duct 15 and at least one second duct 16 for injecting compressed air into the joining chamber 12, the first duct and the second duct entering the joining chamber 12 from two opposite sides relative to the middle longitudinal plane PL and offset from each other relative to the longitudinal extension of the joining chamber 12, and the first duct and the second duct are arranged to form corresponding air vortices with opposite rotation directions inside the joining chamber 12, and are operated to twist the line or yarn in the direction of its original twist ("Z" or "S").

[0069] At least one, and advantageously both, of the at least one first injection duct 15 and the at least one second injection duct 16 are constituted by a cylindrical bore as described above, characterized by the ratio Pd as indicated above.

[0070] Advantageously, the at least one first injection duct 15 and the at least one second injection duct 16 are identical to and opposite to each other.

[0071] In the illustrated embodiment, there is a pair of first spray conduits 15 placed side by side and a pair of second spray conduits 16 placed side by side.

[0072] The at least one first injection conduit 15 is constituted by a cylindrical hole passing through the body 11 and opening at two opposite ends 15a, 15b, the first end 15a of the cylindrical hole defining a corresponding first nozzle which opens at the joining chamber 12, and the second end 15b of the cylindrical hole opening at the seat 17. Thus, the first end 15a of the at least one first hole 15 defines a first nozzle.

[0073] Similarly, the at least one second injection conduit 16 is constituted by a cylindrical hole passing through the body 11 and opening at two opposite ends 16a, 16b, the first end 16a of the cylindrical hole defining a corresponding second nozzle which opens at the joining chamber 12, and the second end 16b of the cylindrical hole opening at the seat 17. Thus, the first end 16a of the at least one second hole 16 defines the second nozzle 16a.

[0074] The at least one first nozzle defined by the first end 15a and the at least one second nozzle defined by the first end 16a lead to the joining chamber 12 from two opposite sides relative to the median longitudinal plane PL and are offset from each other relative to the longitudinal extension of the joining chamber 12. The at least one first nozzle and the at least one second nozzle are arranged to form respective air vortices with opposite rotation directions inside the joining chamber 12 for twisting the thread or yarn in the direction according to the original twist of the thread or yarn (in the figure in a Z-shape, an opposite arrangement is provided to join threads or yarns with an S-shaped twist).

[0075] In more detail, the at least one first nozzle and the at least one second nozzle are also arranged on two opposite sides relative to the median transverse plane PT, thus in two diametrically opposite quadrants.

[0076] The longitudinal axes 150 , 160 of the first and second injection ducts 15 , 16 are inclined relative to the median longitudinal plane PL, with which they form an angle α and converge towards a plane containing the longitudinal cutout 13 .

[0077] Preferably, the bonding head 10 also includes a device 20 for injecting an air flow into the bonding chamber 12, for dividing the volume inside the bonding chamber 12 into two longitudinal parts, the two longitudinal parts respectively including the at least one first nozzle and the associated air vortex formed by the first end 15a of the first injection pipe 15, and the at least one second nozzle and the associated air vortex formed by the first end 16a of the second injection pipe 16.

[0078] The injection device 20 is defined at a median transverse plane PT.

[0079] The injection device 20 includes at least one third nozzle 21a leading to the joining chamber 12 for injecting compressed air.

[0080] The at least one third nozzle 21a is defined by a first open end of at least one third hole 21 that passes through the main body 11 and opens at two opposite ends 21a, 21b, the first end of the third hole 21 defines the at least one third nozzle 21a that passes to the bottom of the joining chamber 12, and the second end 21b of the third hole 21 passes to the seat 17.

[0081] Therefore, the first end 21a of the at least one third hole 21 defines the at least one third nozzle 21a; therefore, in the following description, reference will be made to the at least one third nozzle 21a defined by the first opening end of the at least one third hole 21 and consistent with the first opening end of the at least one third hole 21.

[0082] In particular, the third nozzle 21a is defined at the intersection line LI of the median transverse plane PT and the median longitudinal plane PL, and advantageously has a longitudinal axis parallel to this intersection line LI.

[0083] The third nozzle 21 a is arranged in the middle of the bonding chamber 12 .

[0084] As shown in the accompanying drawings, the diameter "d" of the third nozzle 21a is smaller than the diameter "D" of the cylindrical hole forming the at least one first injection pipe 15 and the diameter "D'" of the cylindrical hole forming the at least one second injection pipe 16, wherein it is advantageous that the diameters "D" and "D'" are equal.

[0085] In a preferred embodiment, the ratio of the diameter "d" of the at least one third nozzle 21a to the diameter "D" or "D'" of the cylindrical hole forming the first and second injection conduits 15, 16 is between 0.3 and 0.9.

[0086] The third nozzle 21a (i.e., the injection device 20) injects a compressed air flow into the joining chamber 12, which physically divides the volume inside the joining chamber 12 itself into two longitudinal parts, and in each longitudinal part, the at least one first nozzle and the at least one second nozzle formed by the first and second injection pipes 15, 16 respectively generate a compressed air vortex that operates to twist the thread or yarn fibers in the same direction as the original twist of the thread or yarn fibers.

[0087] In the embodiment shown in the drawings, the body 11 further comprises a transverse slit 22 which crosses the bonding chamber 12 to connect the inner volume of the bonding chamber 12 with the external environment, and the injection device 20 (ie, the third nozzle 21a) is defined at the transverse slit.

[0088] The transverse slit 22 is defined at a median transverse plane PT; it is open at a plane containing the longitudinal cutout 13 and / or at two opposite sides and, viewed in cross section, starting from the plane containing the longitudinal opening towards the bottom of the joining chamber 12, it has a maximum height or depth equal to the height of the joining chamber 12 itself.

[0089] In the embodiment shown in the figures, the transverse slot 22 has a bottom 23 which is tangential to the bottom of the joining chamber 12 and has a rectangular shape.

[0090] Respective walls 24, parallel to the median transverse plane PT and facing each other, extend from the edge of the bottom 23 parallel to the median transverse plane PT. Each wall 24 is connected to a surface 25 flaring upwards and terminating in a lip portion 14a, 14b.

[0091] The third hole 21 opens with its first end defining the third nozzle 21 a into the bottom 23 .

[0092] The bonding head 10 then comprises a base 26 for attachment to the bonding device 100 .

[0093] The base 26 supports the main body 11 , and the main body 11 may be placed thereon and fixed thereon or formed integrally therewith.

[0094] The base 26 comprises a groove 27 for centering and / or fixing on the joining device 100 and has a threaded hole 28 in which a tool for removing the joining head 10 from the joining device 100 can engage.

[0095] A seat 17 is formed in the body 11 at its face opposite the longitudinal cutout 13 and is configured to house in an airtight manner a fitting 18 for distributing compressed air to the at least one injection duct 15 , 16 and possibly to a third orifice 21 .

[0096] The seat 17 has a substantially flat surface 170 into which the second end 15b, 16b of the at least one injection duct 15, 16 opens and whose maximum transverse dimension DTmax is related to the length and the inclination α of the ducts 15, 16. The end of the seat 17 opposite the surface 170 is open for inserting the fitting 18 therein.

[0097] In the embodiment shown, the seat 17 is cylindrical, circular and rectilinear, and the maximum transverse dimension DTmax is the diameter of the circular base, as in Figure 4 What you can see in.

[0098] In fact, increasing the length of the generatrix with minimum length Lmin of the cylindrical hole forming the at least one injection duct 15, 16 so as to obtain a ratio Pd falling within the range defined above, the distance between its second end 15b, 16b and the middle longitudinal plane PL (having the same angle α) is thus increased. This therefore makes it possible to increase the extension of the surface 170. Such an increase is advantageous in that a more stable and safer connection of the joining head 10 on the joining device 100 is ensured, and the tightness between the joined parts is also improved. Greater connection stability ensures that the obtainable joint is higher in quality and greater in repeatability.

[0099] Figure 7 and Figure 8 A joining head 10 is shown which is applied to a device 100 for joining textile threads or yarns by means of compressed air.

[0100] The device 100 is of a type known to those skilled in the art and is here only schematically represented and generally described in some parts thereof that are helpful for understanding the present disclosure.

[0101] The device 100 includes a main body 101 for supporting and accommodating, and the bonding head 10 as described above is fixed on the top of the main body 101 for supporting and accommodating.

[0102] The supporting and containing body 101 supports and contains a plurality of elements for gripping, cutting, pneumatically preparing the ends of the threads or yarns to be spliced ​​and withdrawing them into the splicing chamber 12 .

[0103] In short, arranged near each of the two opposite ends 12a, 12b of the joining chamber 12 are: a guide element for the corresponding end of the wire or yarn to be joined, a preparation device 29 for pneumatically pre-treating the end of the wire or yarn to be joined, a retraction rod 30 for retracting the pre-treated end of the wire or yarn from the corresponding preparation device 29 in the direction of the joining chamber 12 and into the joining chamber 12, a clamping device 31 provided with a fixed part and a movable part for clamping the end of the wire or yarn introduced into the interior of the joining chamber 12, a cutting device 32 for cutting the end of the wire or yarn leaving the two opposite ends 12a, 12b of the joining chamber 12, and a reference and guide plate for the end of the wire or yarn.

[0104] Then, a pipe 19 for supplying compressed air is formed in the main body 101 for supporting and accommodating, the pipe 19 terminates in a fitting 18 inserted in a seat 17 formed in the main body 11, and the second ends 15b, 16b and 21b of the at least one first injection pipe 15, the at least one second injection pipe 16 and the at least one third hole 21 are connected to the pipe 19 respectively.

[0105] Furthermore, an additional conduit for supplying compressed air in the preparation device 29 is defined in the main body 101 for supporting and containing.

[0106] One or more valves are then provided which allow compressed air to be supplied via the supply line 19 and the at least one injection line 15 , 16 and possibly the third orifice 21 into the joining chamber 12 and into the preparation device 29 via corresponding supply lines.

[0107] The device 100 also includes a cover 36 for temporarily closing the longitudinal cutout 13 of the joining chamber 12, which is only required when the longitudinal cutout 13 of the joining chamber 12 is closed. Figure 3 Schematically depicted in .

[0108] The cover 36 is movable between an open position and a closed position of the longitudinal cutout 13 .

[0109] Then, elements for controlling and commanding the various components and assemblies (valves) of the device 100 are provided.

[0110] With reference to the drawings, the operation of the apparatus 100 according to the present disclosure will now be generally described.

[0111] Both ends of the wire to be joined and coming from opposite directions relative to the joining chamber 12 are inserted in the joining chamber 12 through the longitudinal cutout 13 so that the free end of each of them protrudes from a respective one of the two opposite ends 12a and 12b.

[0112] The two ends of the wire are then fixed by means of a clamping device 31, and their ends protruding outside the longitudinal chamber 12 are cut by means of a cutting device 32 and introduced into a preparation device 29, into which a jet of compressed air is injected for preparing the ends to be joined by untwisting, spreading and parallelizing the corresponding fibers.

[0113] The end thus prepared is then retracted into the joining chamber 12 by retracting the rod 30 .

[0114] After the cover 36 has been brought to the closed position of the longitudinal cutout 13 , compressed air is supplied into the joining chamber 12 to operate the joining of the ends of the wires.

[0115] Compressed air is supplied into the joining chamber 12 through the at least one first and second jetting conduits 15, 16 and the at least one third hole 21. The air supplied to the at least one first and second jetting conduits 15, 16 enters the joining chamber through the at least one first nozzle and the at least one second nozzle, respectively, which generate two vortices in opposite rotation directions, respectively, thereby operating the twisting of the fibers at the two ends in the same direction as the original twist of the thread.

[0116] The two vortices are kept separate from one another by the compressed air flow which is fed into the joining chamber 12 via the third nozzle 21 a .

[0117] The compressed air introduced into the bonding chamber 12 is discharged outwardly and through the two opposite ends 12a and 12b of the bonding chamber 12, through the possible transverse slits 22 and / or through the possible transverse slits formed in the cover.

[0118] Once the splicing is complete, the cover 36 is brought to the open position and the spliced ​​wire is withdrawn from the splicing chamber 12 .

[0119] The splicing head of the present disclosure is advantageous in that it can repeatedly provide high quality splices for various threads or yarns over time, thereby reducing the risk of misuse and malfunctions due to the use of a splicing head that is not suitable for the type of thread or yarn to be processed. The splicing head according to the present disclosure can be used to splice various threads or yarns that are even very different from each other in terms of properties, yarn count, twist, etc.

[0120] The joining head according to the present disclosure allows reducing the turbulent areas that would be generated in the joining chamber, delays the transition of the joining air jet movement from spiral laminar flow to spiral turbulence, delays the formation of the area where the air flow ejected by the injection duct is mixed, thereby increasing the mechanical strength and appearance of the joints between the lines and yarns.

[0121] Furthermore, the joining head according to the present disclosure allows increasing the contact surface between the joined parts and the compressed air circuit of the joining device, which makes the joining more stable and thus improves the repeatability and stability of the action of joining the threads or yarns.

[0122] The joining head for joining textile threads or yarns by compressed air and the device for joining textile threads or yarns by compressed air comprising such a joining head are susceptible to numerous modifications and variations, all of which are within the scope of the present disclosure; moreover, all the details may be replaced by technically equivalent elements.

Claims

1. A joining head (10) adapted for joining textile yarns by compressed air (100) and comprising: - a body (11) in which is formed a longitudinally extending joining chamber (12), which is open at two opposite ends (12a, 12b), is provided at the top with a longitudinal cutout (13) for introducing the yarns or threads to be joined, and has a median longitudinal plane (PL) along at least one longitudinal section, - at least one injection duct for injecting compressed air into the joining chamber, the injection duct consisting of a cylindrical hole formed in the body and opening at the two opposite ends, the first end of the cylindrical hole opening at the joining chamber (12) forming a nozzle for injecting a stream of compressed air in the joining chamber, and the second end of the cylindrical hole opening at a seat formed in the body forming an orifice for the entry of the stream of compressed air, It is characterized in that The ratio (Pd) of the length of the generatrix of the cylindrical hole having the minimum length (Lmin) to the maximum transverse dimension (Dmax) of the nozzle is greater than or equal to 2.

8.

2. The joining head (10) according to claim 1, characterized in that The ratio (Pd) is less than or equal to 15.

3. The joining head (10) according to claim 1 or 2, characterized in that The ratio (Pd) is between 3 and 8.

4. The joining head (10) according to claim 1 or 2, characterized in that The ratio (Pd) is equal to 3.

5. The joining head (10) according to claim 1, characterized in that At least at the nozzle, the joining chamber (12) has, in a cross section orthogonal to the longitudinal extension, a circular shape interrupted by the longitudinal cutout (13).

6. The joining head (10) according to claim 1, characterized in that The cylindrical bore has a longitudinal axis (150, 160) lying in a plane orthogonal to the longitudinal extension of the engaging chamber (12).

7. The joining head (10) according to claim 5 or 6, characterized in that The maximum transverse dimension (Dmax) of the nozzle is constituted by a maximum chord (AB) subtending a maximum arc defined by the intersection of the cylindrical bore and the joining chamber (12) on a plane orthogonal to the longitudinal extension of the joining chamber (12).

8. The joining head (10) according to claim 1 or 2, characterized in that The cylindrical hole has a circular cross-section.

9. The joining head (10) according to claim 1 or 2, characterized in that The longitudinal axis of the cylindrical bore forms an angle (α) with the median longitudinal plane (PL) comprised between 0° and 65°.

10. The joining head (10) according to claim 1 or 2, characterized in that The joining head comprises at least one first injection pipe and at least one second injection pipe for injecting compressed air into the joining chamber (12), wherein the at least one first injection pipe and the at least one second injection pipe lead to the joining chamber from two opposite sides relative to the middle longitudinal plane (PL) and are offset from each other relative to the longitudinal extension of the joining chamber (12), and the at least one first injection pipe and the at least one second injection pipe are arranged to form corresponding air vortices with opposite rotation directions in the joining chamber (12) for twisting the yarn or thread in the direction of the original twist of the yarn or thread, wherein at least one of the first injection pipe and the second injection pipe is formed by the cylindrical hole.

11. The joining head (10) according to claim 10, characterized in that Each of the first spray conduit (15) and the second spray conduit (16) is constituted by the cylindrical hole.

12. The joining head (10) according to claim 1 or 2, characterized in that The seat (17) is formed in the body (11) at a face opposite to the longitudinal cutout (13) and is configured to airtightly accommodate a fitting (18) for distributing compressed air to the at least one injection duct (15, 16), wherein the seat (17) has a substantially flat surface (170) to which the second end (15b, 16b) of the at least one injection duct (15, 16) opens.

13. A device (100) for joining textile yarns by means of compressed air, characterized in that The device comprises a main body for supporting and containing, the main body for supporting and containing is used to support and contain a plurality of elements for clamping (31), cutting (32), pneumatically preparing (29) the ends of the yarns or threads to be joined and retracting the ends of the yarns or threads to be joined into a joining chamber (12), and means for actuating the elements, wherein the joining chamber (12) is defined by a joining head (10) according to any one of claims 1 to 12, and the joining head is removably associated with the main body for supporting and containing.

14. The device (100) according to claim 13, characterized in that It also comprises a cover (36) for closing the longitudinal cutout (13) of the joining chamber (12), the cover (36) being associated with the supporting and containing body in a manner movable between an open position and a closed position of the longitudinal cutout (13).

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