Threading apparatus

Abstract: To provide a threading apparatus that can thread yarn (Y) by feeding compressed air when the yarn is fed from a large diameter portion (1a) of a spindle member (1) to a small diameter portion (1b) of the spindle member (1) preceding the large diameter one. A spindle member is divided and a pipe (2) consisting of a filter member is installed in the middle of the spindle, so that when compressed air is injected from the rear end of the spindle having a large diameter toward its tip having a small diameter and preceding the rear end, a suction flow that sucks external air at the rear end is generated while excessive air is discharged to the exterior through the filter member (2), thereby maintaining a yarn feeding air flow in the center of the spindle member (1). Thus, the present invention can provide a threading apparatus that can feed compressed air to thread yarn from the rear end having a large diameter toward the preceding small diameter portion.

Description: The invention relates to a threading apparatus according to the preamble of claim 1. Background of the Invention Conventional threading apparatuses feed yarn by a suction flow generated by compressed air injected through a path with a uniform diameter or from a small diameter path to a large diameter path. In addition, when yarn is fed from the large diameter path toward the small diameter path, the compressed air method may cause air to flow in the opposite direction and prevent a suction flow from being generated, thereby hampering threading. Thus, an air sucker is installed at an outlet of the small diameter path preceding the large diameter path in order to obtain a suction force (DE-A-4 308 392). Consequently, when spinning is begun or a yarn is cut, a conventional spinning machine uses a suction member to suck the end of the yarn wound around a package, and then use a roller to grip the end in order to transfer it to the rear end of a spindle in a spinning section. When inserting the end of the yarn into a yarn path in the spindle, the spinning machine engages the air sucker with the tip of the spindle while feeding the yarn using the roller, guides the end of the yarn to the front of the spindle using a suction flow from the air sucker, and pieces together the end of the yarn and a sliver fed from a draft device located on the upstream side. It is an object of the present invention to provide a yarn feeding apparatus that does not require an air sucker that is required by the conventional spinning machine and that blows compressed air from the rear of a spindle to enable yarn to be threaded from the rear end of the spindle, which has a large diameter, toward its small diameter portion. Summary of the Invention To achieve this object, the present invention is characterized by the features in the characterizing portion of claim 1. Thus, when compressed air is injected from the large diameter path toward the small diameter path, the excess air flow is discharged to the exterior through an air discharge region for example in form of a filter member to prevent a counterflow in order to preserve the yarn feeding air flow in the middle of the path, thereby enabling the yarn to be fed toward the small diameter portion. The outside of the filter member may be covered with a porous cover. Thus, even if the length of the filter member is increased to increase its surface area, the amount of air discharged to the exterior can be adjusted by increasing and reducing the area of the pores of the external porous cover, thereby maintaining at a constant force the yarn feeding air flow formed in the middle of the yarn path. In addition, since the length of the filter member can be increased, clogging does not occur, so that function degradation is prevented. Since the threading apparatus can be used in the spindle section of the conventional air spinning machine, threading can be achieved by blowing compressed air from the rear end of the spindle without the use of the air sucker that is required in conventional threading. Brief Description of the drawings Figure 1 is a sectional view showing the structure of the spindle section according to the present invention of an air jet spinning machine, Figure 2 is a sectional view showing a second embodiment of a spindle section according to the present invention, Figure 3 is a sectional view showing a third embodiment of a spindle section according to the present invention, Figure 4 is a sectional view of a spinning machine with a conventional spindle member, Figure 5 is a sectional view showing the piecing operation of a conventional spinning section, and Figure 6 is a front view of the overall spinning machine. Detailed Description of the Preferred Embodiments A spinning machine is composed of a large number of spinning units U, as shown in Figure 6. A sliver L is fed to a draft device D and is formed into spun yarn Y by a spinning section Sp. The spun yarn Y then passes through a nip roller Rn and a slub catcher Z, and is wound up in a winding section W. P is a piecing apparatus for performing a piecing operation, which is configured to travel at the bottom of the interior of the spinning machine along its longitudinal direction. Fig.4 shows detailed the draft device D and the spinning section Sp. The draft device D consists of a rear roller Rb, a third roller Rt, a second roller Rs having an apron, and a front roller Rf. Each roller consists of a pair of rollers. The draft device D drafts the sliver L supplied via a sliver guide T, to a specified thickness and performs a draft operation when the rotating speed of each roller is gradually increased. The sliver L, which has been drafted to the specified thickness while passing through the draft device D, is supplied to the spinning section Sp consisting of a nozzle member N and a spindle member S, in which it is formed into spun yarn Y. The spinning section Sp is composed of the nozzle member N having air nozzles n that cause a whirling air flow to act on a fiber bundle output from the draft device D, the spindle member S having its tip located at a point at which the whirling air flow from the nozzle member N acts and having a hollow portion that acts as a yarn path, and a guide member 7, the tip of which protrudes toward an inlet of the spindle members. The spindle member S includes the stationary spindle 1 which has a yarn path formed in its center, and the nozzle member N the air nozzles n of which are drilled in the tangential direction and from which compressed air is injected toward the tip of the spindle 1 to generate a whirling air flow in order to form the spun yarn Y. The fiber bundle output from the front roller Rf in the draft device is drawn into a casing through a hole 9 in a supporting part 8 for the guide member 7 by means of a suction flow generated by the action of the air flow from the air nozzles n. While the fiber bundle is being formed into yarn, the front ends of all fibers in the fiber bundle are drawn from the periphery of the guide member 7 and guided into the spindle 1. In addition, the rear ends of the fibers are reversed from the tip of the spindle 1 by both the suction flow and the whirling air flow from the air nozzles n, and the fibers are mutually separated. The separated fibers are exposed to the whirling air flow from the air nozzles n, and are guided into the spindle 1 while being spirally wound around the fiber bundle being formed into yarn, resulting in true twisted spun yarn. The guide member 7 acts as a pseudo core by preventing twisting from being propagated during the formation of the yarn. As described above, the fibers separated at the tip of the spindle 1 are formed into spun yarn by being drawn into the yarn path in the middle of the spindle 1 while being swung (ballooned) by the whirling air flow. Thus, the tip of the spindle 1 has an optimal bore diameter relative to the diameter of a spun yarn. This bore diameter  may be 1.1 mm relative to the diameter of the spun yarn from Ne 20 to 40. The bore diameter of a spun yarn outlet at the rear end of the spindle 1 is larger. The difference in bore diameter improves the spinning capability and enables the end of the yarn drawn out from a package to be introduced from the rear end of the spindle 1 during piecing. When the yarn is cut during spinning by the conventional spinning machine, the spindle member S supported by a supporting member h is separated from the nozzle member N using an air cylinder Cs to engage an air sucker member As with the tip of the spindle 1 as shown in Figure 5. In addition, by feeding the yarn using a feed roller R in a transfer apparatus Ta that transfers the spun yarn Y drawn from a package (not shown in the drawings), and sucking the yarn using the air sucker member As, the end of the yarn is guided to the front of the spindle members and subsequently it is combined with the sliver L that has been drafted passed through the draft device D to the specified thickness. Winding is then begun to carry out piecing. This operation will not be described in detail. The present invention enables yarn to be threaded into the spindle member S without the use of the air sucker required with the conventional threading method as will be described in the following. As shown in Figure 1, the spindle is segmented and comprises a spindle member 1a at its tip, a conduit 4 and a nozzle holder 5 separated from the spindle member 1a by a distance k, a pipe 2 consisting of a sintered metal element, installed in the middle of the spindle as a filter member and covered with a porous member 3, so that compressed air supplied from an air supply hole 5a in the nozzle holder 5 advances without a counterflow and is injected toward the tip of the spindle from a fine gap 6a between the holder 5 and a funnel-shaped tube 6 at the rear end of the spindle. Most of the air, however, is discharged from the gap k to the exterior through the filter member. Since the porous member 3 has a plurality of fine pores 3a, the discharge of the supplied air progresses very slowly. Thus, the air flowing through the middle of the spindle member is discharged to the exterior and through the yarn path at the tip of the spindle. In this manner, the amount of air discharged to the exterior through the filter member and the amount of air discharged to the exterior through the yarn path at the tip of the spindle can be varied according to the number of fine pores 3a in order to adjust the capability of transferring the yarn through the yarn path in the spindle. The injection of air from the fine gap 6a between the holder 5 and the funnel-shaped tube 6 at the rear end constitutes an air sucker effect to generate a suction flow that sucks air outside the funnel-shaped tube 6 into the spindle. The conduit 4 acts as a tube for straightening the flow of air in the middle of the conduit 4 as a path for the sucked external air. That is, the end of the yarn introduced together with the sucked external air flow from the rear end of the spindle moves through the middle of the conduit 4. Only a pipe 2a consisting of a filter member may be used without using the porous member 3, as shown in Figure 2. In this case, however, the length K2 of the filter section must be reduced to reduce its surface area. If the length of the filter section is too great, the amount of released air increases to reduce the force of the air flow that transfers the end of the yarn through the middle of the spindle, thereby preventing threading. In addition, if a pipe 2b consisting of a filter member of a length K3 is provided in a portion of the spindle 1, as shown in Figre 3, a sufficient threading effect can be obtained from the air injected from the air supply hole 5a. Although threading can be achieved by the configuration shown in Figure 2 or 3, it requires that the length K2 or K3 of the filter section be reduced, so the porous member 3 covers the outside of the pipe 2 consisting of the filter member in order to allow the length K1 of the filter section to be increased, as shown in Figure 1. This configuration can increase the lifetime of the apparatus by preventing the clogging of the filter member that obstructs the passage of air, thereby enabling the present spindle structure to be used for the current spinning machine. In an experimental flow of air, when 85 liters/minute of air were injected at an air pressure of 4 kg/cm 2 , 14 liters/minute of air were sucked from the rear end of the spindle and 20.5 liters of air flowed from the tip of the spindle. That is, the leakage from the filter member to the exterior was 78.5 liters. In this case, 24 fine pores 3a were provided in the porous member 3 and had a bore diameter of  0.6 mm. When the number of pores 3a at a bore diameter was increased to 32 and 85 liters/minute of air were injected at an air pressure of 4 kg/cm 2 , as described above, 19 liters of air were sucked from the rear end of the spindle and 19.5 liters of air flowed from the tip of the spindle. Thus, the number of pores 3a could be varied to adjust the flow of air through the yarn path in the spindle. The material of the filter member is not limited to the sintered metal element but may be fibers, resin, or ceramics, as long as it is porous and releases air slowly. As described above, in the present invention the spindle is divided and a pipe consisting of the filter member is installed in the middle of the spindle, so when compressed air is injected from the rear end of the spindle having a large diameter toward its tip having a small diameter, a suction flow that sucks external air at the rear end is generated while excessive air is discharged to the exterior through the filter member, thereby maintaining a yarn transferring air flow in the center of the spindle member. Thus, when spun yarn is fed from the rear end of the spindle member having a large diameter toward its tip having a small diameter, compressed air can be blown from the rear end having a large diameter to transfer the spun yarn by means of a suction flow from the rear end having a large diameter, toward the tip having a small diameter, instead of a suction force from the tip of the spindle. In addition, since the outside of the pipe consisting of the filter member is covered with the porous member, the spun yarn can be threaded appropriately even if the length of the filter member is increased, thereby preventing the filter member from being clogged to increase the life expectancy of the apparatus.

Claims: Threading apparatus with a feeding path for feeding a yarn in a textile machine, particularly in a spindle section of an air jet spinning machine that produces a spun yarn (y) by twisting non-twisted, drafted fiber bundles, wherein the feeding path has a spun yarn outlet the inner diameter of which is larger than that of the fiber bundle inlet, characterized in that the feeding path includes an air discharge region in an intermediate portion between the inlet and the outlet for discharging a portion of the air from the yarn feeding path to the exterior. Threading apparatus according to claim 1, characterized in that the discharge region comprises a filter member (2) of a porous material. Threading apparatus according to claim 2, characterized in that the porous material is a sintered metal. Threading apparatus according to claim 2 or 3, characterized in that the outside of the filter member (2) is covered with a porous member (3). Threading apparatus according to claim 1, characterized in that the spindle section (Sp) comprises a spindle having a spindle member (1a), a conduit (4) separated from the spindle (1a) by a predetermined distance (k), a nozzle holder (5) connected with the conduit (4) and a pipe (2) consisting of a filter material installed in the middle of the spindle member (1a). Threading apparatus according to claim 5, characterized in that the pipe (2) is covered with a porous member (3). Threading apparatus according to claim 5 or 6 characterized in that the filter material is sintered metal.

Inventors: OKAMOTO AKIRA, OKAMOTO, AKIRA
Applicants: MURATA MACHINERY LTD, MURATA KIKAI KABUSHIKI KAISHA
Application year: 1998
Main classification: D01H15
IPC codes: D01H9, D01H4, D01H1, D01H15