SUCTION DEVICE FOR YARNTHREADING

Abstract: A suction gun (1) has a first injection nozzle (2) and a second injection nozzle (6). The first and second injection nozzles (2, 6) inject pressurized water, thereby to draw a yarn (Y) with a suction force of the pressurized water. The second injection nozzle (6) has a plurality of jets (6a), respective axes (A₁, A₂, ...) of which intersect with each other at an intersection point (P). The intersection point (P) is located in a position displaced by E, which is preferably in a range from 0.2mm to 0.9mm, from an axis (L) of a through hole (6d) which is included in a pressurized liquid exhaust passage (20).

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a suction device (hereinafter also referred to as "suction gun") for drawing and holding a yarn by pressurized liquid such as pressurized water, thereby to thread the yarn to a desired position. Description of the Prior Art It is well known in the art that a movable suction gun for drawing and holding a running yarn is employed in order to thread the yarn to a desired apparatus such as a godet roller, a bobbin of a winder or a yarn guide. In such a suction gun, pressurized air or pressurized liquid is employed as actuating fluid for drawing the yarn. A preferable type of suction gun employing pressurized water as actuating fluid is disclosed in US-A-4,666,590, which comprises first and second injection nozzles (suction nozzles). The first injection nozzle is provided oppositely to an inlet port of a pressurized liquid exhaust pipe, so that the yarn is thrusted into the interior of the pressurized liquid exhaust pipe (yarn guide pipe) by injection force of the pressurized water injected from the first injection nozzle. An internal space of the pressurized liquid exhaust pipe defines a pressurized liquid exhaust passage. The second injection nozzle is provided in the upstream portion of the pressurized liquid exhaust passage, to obliquely inject pressurized water into the pressurized liquid exhaust passage. The yarn in the pressurized liquid exhaust passage is sucked and drawn by injection force of the pressurized water from the second injection nozzle, to be discharged from the suction gun with the pressurized water. In such a two-stage injection type suction gun, an injection nozzle having a plurality of jets is employed as the second injection nozzle. In a prior art, the plurality of jets are so directed that axes thereof intersect with each other at a single point on the axis of a through hole forming a part of the pressurized liquid exhaust passage, which is identical to an axis of the first injection nozzle. Therefore, the pressurized water introduced into the pressurized liquid exhaust pipe by the first injection nozzle is subjected to interference by the pressurized water from the second injection nozzle, and a yarn sucking force or tension in suction gun is remarkably weakened. As the result, a large amount of pressurized water must be supplied in order to apply sufficient suction force to the yarn, whereby the cost required for water supply is increased. SUMMARY OF THE INVENTION An object of the present invention is to provide a suction device for yarn-threading which can apply sufficient tension in suction to a yarn without requiring a large amount of pressurized liquid. According to the present invention, a suction device for yarn-threading comprises a first injection nozzle having a first jet for injecting first pressurized liquid; a pressurized liquid exhaust pipe having an inlet port facing the first jet with a predetermined yarn introducing space and defining a pressurized liquid exhaust passage by internal space of the pressurized liquid exhaust pipe, the pressurized liquid exhaust passage including a through hole; and a second injection nozzle having a plurality of second jets around the through hole for obliquely injecting second pressurized liquid into the pressurized liquid exhaust passage; and respective axes of the second jets intersect with each other at an intersection point displaced by a predetermined distance from an axis of the through hole. According to a preferred embodiment of the present invention, the predetermined distance has a value within a range of from 0.2mm to 0.9mm. According to the present invention, injection force of the first pressurized liquid injected from the first injection nozzle does not interfere with that of the second pressurized liquid injected from the second injection nozzle, whereby suction force for the yarn is effectively increased. In other words, the amount of pressurized liquid required for obtaining prescribed suction force or yarn tension in suction can be reduced. These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram for illustrating the situation of applying a suction gun in yarn-threading; Fig. 2 is a partially fragmented sectional view showing a suction gun according to a preferred embodiment of the present invention; Fig. 3 is a partially enlarged view of the suction gun shown in Fig. 2; Fig. 4 is a diagram showing a positional relation between a second injection nozzle and a pressurized water chamber; Figs. 5 and 6 are sectional end views taken along lines V - V and VI - VI in Fig. 3, respectively; Fig. 7 is a graph showing the result of an experiment in first embodiment; and Fig. 8 is a diagram showing a second injection nozzle employed in third embodiment. DESCRIPTION OF THE PREFERRED EMBODIMENTS Fig. 1 is an explanatory diagram illustrating a yarn-threading operation employing a suction gun 1. Before explaining internal structure of the suction gun 1 according to an embodiment of the present invention, description is made on the situation in which the suction gun 1 is employed in the yarn-threading operation with reference to Fig. 1. The suction gun 1 is employed in order to thread a synthetic yarn Y to a rotating bobbin 105, for example. The yarn Y extruded through spinning holes of spinnerets (not shown) provided in the lower portion of a spinning block 101 is derived from a plurality of ducts 102. The yarn Y running at a high speed is supplied to yarn winding device 106 through godet rollers 103. A plurality of such winding devices 106 are provided in correspondence to each of the ducts 102, and each of the winding device 106 has a winder 104 and a bobbin 105 mounted on the same to rotate with a spindle (not shown) of the winder 104. In order to thread one of the yarns Y to the corresponding winding device 106, pressurized water W is supplied to the suction gun 1 from a water pressurizing pump 109 through a hose 110. When the suction gun 1 is moved toward the bobbin 105 while picking-up and pulling the running yarn Y with suction force induced by an injection of the pressurized water W, the yarn Y captured by the suction gun 1 is caught and wound on the rotating bobbin 105. Thus, yarn-threading operation is completed with respect to the first bobbin 105. Water discharged from the suction gun 1 and waste yarn are discharged to a waste yarn disposal device 108 through a hose 111. In order to perform yarn-threading operation of another yarn Y to another winding device 106, the suction gun 1 is manually moved to perform operation similar to the above. Namely, the suction gun 1 of this embodiment is a suction device which employs pressurized water as pressurized liquid. Details of the yarn disposal device 108 are disclosed in US-A-4,666,590, for example. Fig. 2 is a partially fragmented sectional view of the suction gun 1, and Fig. 3 is a partially enlarged view thereof. The suction gun 1 comprises a substantially straight-tubular gun body 1a and a pressurized water introducing pipe 1b extending from a side wall of the gun body 1a. The pressurized water introducing pipe 1b receives the pressurized water W supplied from the hose 110 of Fig. 1 from a pressurized water inlet port 9 provided in an end thereof. A valve 10 is provided in a part of the pressurized water introducing pipe 1b, to be opened/closed by operation of a valve handle 10a. The other end of the pressurized water introducing pipe 1b is fixed to the side wall of the gun body 1a. The pressurized water W is introduced into the interior of the gun body 1a through a pressurized water inlet hole 15, being circular in section, which is provided on the side wall of the gun body 1a. A part of the pressurized water W (first pressurized water) is guided toward the forward end of the gun body 1a through a pressurized water feed path 13 which is provided in the interior of the body 1a. A first injection nozzle 2 having a first yet 2a is mounted on the forward end of the body 1a. The pressurized water W is fed to the first injection nozzle 2, to be injected from the first jet 2a rightwardly in Fig. 2. Most part of the body 1a is formed by a pressurized liquid exhaust pipe 3 yarn guide pipe. The pressurized liquid exhaust pipe 3 is formed by sequentially screwing first to third tubular members 3a to 3c. A pressurized liquid exhaust passage 20 is defined and formed by an internal space of the pressurized liquid exhaust pipe 3, to substantially linearly extend from an end of the pressurized liquid exhaust pipe 3 to the other end thereof. An inlet port 4a of the first tublar member 3a is positioned to face the first jet 2a with a yarn introducing space 21. Thus, the pressurized liquid from the first jet 2a is injected into the pressurized liquid exhaust passage 20. This pressurized liquid exhaust passage 20 is formed by respective internal passages 5a, 7 and 5b of the first to third tubular members 3a to 3c and a through hole 6d formed in a second injection nozzle 6 as hereinafter described. In yarn-threading operation, the suction gun 1 is manually moved to introduce the yarn Y into a yarn introducing space 21. The yarn Y is thrusted into the pressurized liquid exhaust passage 20 with the pressurized water injected from the first jet 2a by injection force of the pressurized water, whereby the suction gun 1 captures the yarn Y. The pressurized water and the yarn Y pass through the pressurized liquid exhaust passage 20, to be discharged through an outlet port 4b into the hose 111 shown in Fig. 1. The second injection nozzle 6 is assembled in a predetermined position of the pressurized liquid exhaust passage 20. As shown in Fig. 4, the second injection nozzle 6 has a shank 6c, a nozzle portion 6b and a sealing part 6e, all of which are integrated with each other. In the nozzle portion 6b, four second jets 6a are formed. The through hole 6d is formed through the seeling part 6e, the shank 6c and the nozzle portion 6b. The second jets 6a are positioned to surround the through hole 6d. Although the sectional shape of the through hole 6d is arbitrary, it is preferred to be a circle. As hereinafter described, an axis L of the through hole 6d has an important meaning in the embodiment, and it is defined by a line passing through the central point of the circle, when the sectional shape is the circle. When the sectional shape is an ellipse, the axis L is defined by a line passing through a point at which a major axis and a minor axis defined on a plane including the ellipse are crossing each other. As shown in Fig. 4, an internal space 8a is defined in the interior of the first tubular member 3a. The diameter of the internal space 8a is larger than that of the shank 6c and substantially identical to the diameter of the nozzle portion 6b. Thus, an annular pressurized water chamber 8 shown in Fig. 3 is formed by inserting the second injection nozzle 6 into the internal space 8a. The pressurized water chamber 8 opens to the pressurized water inlet hole 15. Therefore, within the pressurized water externally supplied through the pressurized water inlet hole 15, a part (second pressurized water) not being supplied to the first injection nozzle 2 flows into the pressurized water chamber 8. The pressurized water in the pressurized water chamber 8 is obliquely injected into an internal passage 7 through the second jets 6a. The internal passage 7 is formed by combination of a truncated-conical injection chamber 7a existing in the vicinity of opening positions of the second jets 6a and a tubular passage 7b extending from the injection chamber 7a. By injection force of the pressurized water injected from the second jets 6a, further tension in suction is applied to the yarn Y in a direction toward the outlet port 4b shown in Fig. 2. Thus, larger suction force acts on the yarn Y. The pressurized water injected from the second jets 6a is also discharged from the outlet port 4b. Description is now made on the direction of arrangement of the second jets 6a corresponding to the feature of the present invention. The direction of the second jets 6a is so determined that axes A₁ to A₄ thereof (Fig. 2 shows only A₁ and A₂) intersect with each other at an intersection point P, which is located in a position displaced by a prescribed distance (hereinafter referred to as "offset distance") E from an axis L of the through hole 6d. The intersection point P is given in the internal passage 7, and preferably, it is given in the tublar passage 7b. In this embodiment, the first jet 2a; the internal passage 5a, 7 and 5b forming the pressurized liquid exhaust passage 20; and the through hole 6d are coaxial with each other. At least, it is preferred that the axis of the first jet 2a coincides with the axis L of the through hole 6d. Assuming that symbol A represents a straight line passing through the intersection point P and being parallel to the axis L of the through hole 6d, the straight line A is at the same angle ϑ with respect to the axes A₁ to A₄. The inclining angle ϑ of the axes A₁ to A₄ of the second jets 6a from the line A (accordingly, from the axis L) may be arbitrary decided. Preferably, the inclining angle ϑ is 3° to 20°, and most preferably, it is 5° to 15°. The diameter of the pressurized liquid exhaust passage 20 may be decided in response to the sectional size of the yarn Y to be threaded. It is preferable that the diameters of the internal passage 5a and the through hole 6d are selected in the range of from 1.5 to 8.0mm, that of the tubular passage 7b is from 2.0 to 15.0mm, and that of the tubular passage 5b is from 2.5 to 20.0mm. Fig. 5 is a sectional end view taken along the line V - V in Fig. 3, in which respective opening portions of the second jets 6a are arranged at isometric intervals (360 ÷ 4 = 90° in this embodiment) about the straight line A. Fig. 3 corresponds to a sectional view taken along the line III - III in Fig. 5. Fig. 6 shows such circumstances as a partially enlarged sectional view taken along the line VI - VI in Fig. 3. As hereinabove described, the intersection point P is located in the tubular passage 7b. When pressurized water is injected along the axes A₁ to A₄ of the second jets 6a, the pressurized water flows into the tubular passage 7b toward the intersection point P. According to such structure, the intersection point P is set in the position displaced by the offset distance E from the axis L of the through hole 6d, whereby the first pressurized water introduced into the pressurized liquid exhaust passage 20 with the yarn Y by the first injection nozzle 2 which is coaxial to the through hole 6d is not subjected to interference by the second pressurized water from the second injection nozzle 6. Therefore, force of the second pressurized water from the second injection nozzle 6 is superposed on force of the first pressurized water from the first injection nozzle 2 in the tubular passage 7b, whereby the suction force applied to the yarn Y is remarkably increased. By setting the offset distance E at a specific value, the pressurized water sufficiently fills up the tubular passage 7b, and the yarn Y smoothly flows through the tubular passage 7b and the internal passage 5b (Fig. 2) by the pressurized water to obtain larger suction force. Description is now made on the results of experiments for measuring difference in yarn suction force in case of providing a specific value as the offset distance E and in case of offset distance E = 0. In the following embodiments, respective symbols indicate the following amounts: d₀ : diameter of the first jet 2a d : diameter of forward end portions of the second jets 6a (Fig. 3) N : number of the second jets 6a ϑ : angle of intersection of the axes A₁ to A₄ of the second jets 6a and the straight line A (Fig. 3) D : inner diameter of the tubular passage 7b (Figs. 3 and 6) E : offset distance (Fig. 6). An offset in same side with the pressurized water inlet hole 15 of Fig. 2 is expressed by the sign "-" and an offset in opposite side to the pressurized water inlet hole 15 with respect to the axis L is expressed by the sign "+". V : suction speed for the yarn P r : pressure of the pressurized water A. First Embodiment Conditions d₀ = 1.0 mm d = 0.6 mm N = 4 ϑ = 10° D = 3.5 mm V = 1500 m/min. P r = 120 Kg/cm²G and 70 Kg/cm²G yarn Y = nylon yarn of 70 deniers and of 12 filaments -1.2 mm ≦ E ≦ + 1.2 mm Result of Measurement Fig. 7 shows the result of measurement of this case as relation between the offset distance E and yarn suction force (tension suction) T(gram). As seen from Fig. 7, the tension in suction T is considerably increased as the absolute value of the offset distance E is increased from 0 mm. Within the measured points, the maximum values in each sides of E > 0 and E < 0 are attained when | E | = 0.3 mm. These maximum values are 120 to 130 % of the tension value in the case of E = 0 mm. The tension in suction T is conversely decreased if the absolute value of the offset distance E is far excessively increased from the value 0.3mm, since, it may be considered that, effective composition of injection forces by the first and second injection nozzles 2 and 6 is lost. Through observation of the graph of Fig. 7 in further detail, the following facts are found: (a) The change rule of the tension in suction T with respect to the offset distance E does not depend on the value of the pressurized water pressure P r . Namely, it is possible to set an optimum offset distance E with no regard to the value of the pressurized water pressure P r . (b) A high tension value in excess of 110 % of the value T in the case of E = 0 mm is obtained within a range of 0.2mm ≦ | E | ≦ 0.9mm Within this range, an especially preferable range is: 0.25mm ≦ | E | ≦ 0.6mm B. Second Embodiment In this embodiment, measurement was performed on various values E as to the amounts of the pressurized water W for obtaining tension in suction T = 0.5 g/denier. The structure of the suction gun 1 was identical to that of the first embodiment. The yarn members Y was prepared as polyethylene terephthalate yarn of 75 deniers and of 36 filaments, to simultaneously draw eight yarns at the speed of V = 5000 m/min. The value of the water pressure P r was employed as the parameter indicating the amount of supply of the pressurized water, whereby the results as shown in Table 1 were obtained. E (mm) P r (Kg / mmG) 0 210 0.2 180 0.3 160 0.9 180 It is understood from Table 1 that tension in suction identical to that in the case of E = 0 is obtained with the water pressure not more than 90 % of that in the case of E = 0 in the range of: 0.2 ≦ | E | ≦ 0.9 Since the water pressure P r is proportional to the square root of amount of supply of the pressurized water, a similar conclusion can be obtained with respect to the amount of supply of the pressurized water. C. Third Embodiment The suction gun 1 was prepared by that of N = 3 (refer to Fig. 8). A nylon yarn of 70 deniers and of 24 filaments was employed with P r = 100 Kg/cm²G. The remaining conditions were identical to those of the first embodiment. With respect to E = 0 mm and E = +0.3 mm, the results shown in Table 2 were obtained. E (mm) T (g) 0 100 + 0.3 150 As seen from Table 2, the tension in suction T in the case of E = +0.3 mm was increased by 50 % of the case of E = 0 mm also in this case. In an experiment of comparing required amounts of water supply for obtaining the same tension with the suction speed V of 4500 m/min., obtained was the result that the required amount of water supply in the case of the offset distance E = +0.3 mm can be saved about 15 % as compared with that in the case of E = 0 mm. It is understood from the aforementioned embodiments that it is extremely effective to set the offset distance E at a specific value excluding zero under various conditions. Preferably, 0.2mm ≦ | E | ≦ 0.9mm and the optimum value is E = +0.3 mm or in proximity thereto. In the aforementioned embodiment, the straight line A is at the same angle ϑ with respect to the axes A₁ to A₄ and the second jets 6a are arranged at isometric angle intervals, such a condition gives uniform tension to the yarn Y. According to the present invention as hereinabove described, the intersection point of the axes of the respective jets included in the second injection nozzle is displaced by a predetermined distance from the axis of the through hole in the pressurized liquid exhaust pipe, thereby to avoid interference between the pressurized liquid introduced into the exhaust pipe by the first injection nozzle and that introduced by the second injection nozzle in an intermediate portion of the exhaust passage. In the exhaust passage, therefore, force of the pressurized liquid from the second injection nozzle is superposed on the force of the pressurized liquid introduced by the first injectionn nozzle. Consequently, suction force applied to the yarn can be extremely increased without increasing the amount of supply of the pressurized liquid.

Claims: A suction device for picking-up and pulling a yarn by injection force of pressurized liquid to thread said yarn to a desired position, said suction device comprising: a first injection nozzle (2) having a first jet (2a) for injecting first pressurized liquid; a pressurized liquid exhaust pipe (3) having an inlet port (4a) facing said first jet (2a) with a predetermined yarn introducing space (21) and a pressurized liquid exhaust passage (20) formed by internal space of said pressurized liquid exhaust pipe (3), said pressurized liquid exhaust passage (20) including a through hole; and a second injection nozzle (6) having a plurality of second jets (6a) around said through hole for obliquely injecting second pressurized liquid into said pressurized liquid exhaust passage (20), characterized in that the respective axes of said second jets (6a) intersect with each other at an intersection point (P) displaced by a predetermined distance from the central axis (L) of said through hole. A suction device in accordance with claim 1, wherein said predetermined distance has a value within a range from 0.2 mm to 0.9 mm. A suction device in accordance with claim 2, wherein said pressurized liquid exhaust passage (20) has a truncated-conical injection chamber (7a) provided in the vicinity of opening positions of said second jets (6a) and a tubular passage (7b) extending from said truncated-conical injection chamber (7a), said intersection point (P) being present in the interior of said tubular passage (7b). A suction device in accordance with claim 2, wherein said axis (L) of said through hole is identical to an axis of said first jet (2a), and respective ones of said axes of said second jets (6a) incline by a predetermined angle (ϑ) from a straight line (A) passing through said intersection point (P) and being parallel to said axis (L) of said through hole, said predetermined angle (ϑ) being common to all of said axes of said second jets (6a). A suction device in accordance with claim 4, wherein respective ones of said second jets (6a) are so arranged that respective ones of said axes of said second jets (6a) are arranged at isometric angle intervals about said straight line (A).

Inventors: SANO, TAKAO
Applicants: TORAY INDUSTRIES, INC.
Application year: 1987
Main classification: B65H51
IPC codes: B65H54, B65H51