Air gun for producing nonwoven fabrics

Abstract: The present invention relates to an air gun for producing nonwoven fabrics, and an object of the invention is to easily introduce a filament at the start of operation. An air gun for producing nonwoven fabrics according to the present invention comprises an inlet for receiving a filament spun from a spinning nozzle. a carrier path for putting sand filament introduced from said inlet on an air flow to deliver the same, and a compressed air blow port opered in the midst of said carrier path to jet and being fed from a compressed air source into the carrier path wherein an exhaust path is provided in the carrier path on the downstream side from the compressed air blow port and when the filament spun from the spinnnig nozzle is introduced into an inlet of the air gun a part of air flowing into the carrier path is discharged through the exhaust path.

Description: The present invention relates to an air gun for producing nonwoven fabrics, and particularly to an air gun for producing nonwoven fabrics in which at the start of operation, a filament can be easily introduced. An air gun for producing nonwoven fabrics, particularly, an air gun for drawing and receiving filaments spun from spinning nozzles at high speed, for putting them on an air flow and for delivering them onto a screen belt to form a web which is intermediate of nonwoven fabric, there has been heretofore proposed a configuration which includes an inlet for receiving filaments spun from spinning nozzles, a carrier path for putting said filaments introduced through said inlet to deliver them, and a compressed air blow port which is opened in the midst of said carrier path to jet air from a compressed air source into the carrier path. In such an air gun as described, an accelerating pipe constituting a part of the carrier path is connected on the downstream side. When compressed air is blown out of the compressed air blow port, a negative pressure is generated in the filament inlet to suck filaments from the spinning nozzle (hereinafter referred to as an ejector performance). In addition, when compressed air is blown out of the compressed air blow port, a traction is applied to the filament downstream from that portion to draw and deliver the filament (hereinafter referred to as a receiving performance). In such an air gun as described, it is desirable for economical operation and prevention of noises caused by air to maintain the receiving performance and reduce the amount of drive air. As the method for maintaining the receiving performance and reducing the amount of drive air, it is possible to reduce the inside diameter of an accelerating pipe to increase flow velocity within the pipe. However, if the inside diameter of the accelerating pipe is reduced, pressure loss increases, and pressure of filament inlet increases by that portion to deteriorate the ejector performance and make it difficult to introduce filaments at the start of operation. It is an object of the present invention to provide an air gun for producing nonwoven fabrics, which is designed so that at the start of operation, filaments spun from a spinning nozzle are easily introduced into an inlet of the air gun. According to a first aspect of the present invention, there is provided an air gun for use in producing nonwoven fabrics comprising an inlet for receiving a filament, a carrier path through which, in use, an air flow delivers said filament from said inlet, a compressed air blow port opening into said carrier path between the ends thereof to supply said air flow and an exhaust path from said carrier path downstream from said compressed air blow port to remove a part of the air flow in the carrier path. According to a second aspect of the present invention, there is provided a control method for an air gun for use in producing nonwoven fabrics comprising an inlet for receiving a filament a carrier path through which in use an air flow delivers said filament from said inlet, compressed air blow port opened in the midst of said carrier path to supply said airflow and an exhaust path in said carrier path downstream from said compressed air blow port, wherein when the filament spun from the spinning nozzle is being introduced into the inlet of said air gun, a part of the air flowing into the carrier path is discharged through said exhaust path. Synthetic resins to be spun by use of an air gun for producing nonwoven fabrics according to the present invention include, for example, polyolefins such as polyethylene, polypropylene, etc.; or ethylene vinyl compound copolymers such as an ethylene vinyl chloride copolymer; styrene resins; vinyl chloride resins such as polyvinyl chloride, polyvinylidene chloride, etc; polyacrylic ester; polyamide; polyesters such as polyethyleneterephthalate, and other synthetic resins that may be spun. These may be used alone or in the form of a mixture. A suitable amount of inorganic pigments or organic pigments may be blended into the synthetic resins. A bundle of spun filaments is preferably introduced into the air gun of the present invention, drawn by an air flow and blown against a collecting surface to form a reb. Usually, a plurality of air guns are arranged since nonwoven fabrics having a practicable width are formed. When filaments are introduced into an inlet of the air gun, the exhaust path remains opened. In this state, a negative pressure at the filament inlet increases, and the filaments are sucked into the inlet merely by moving the filaments close to the inlet of the air gun. Thereafter, the exhaust path is closed, and the filaments are drawn and delivered under constant traction. Preferably, when the filaments are to be introduced into the inlet of the air gun, the exhaust path is opened thereby the negative pressure of the filament inlet can be increased to facilitate the introduction of the filaments. Thereafter, the exhaust path is closed under normal operation, and the filaments can be drawn and delivered with sufficient traction. The invention will be more clearly understood from the following description, given by way of example only, with reference to the accompanying drawings in which: Figure 1 is a half sectional view of the entire air gun of the present invention; Figure 2 is a sectional view of an air gun of the present invention partly enlarged; and Figure 3 is a schematic view of the entire apparatus for producing nonwoven fabrics provided with an air gun of the present invention. An embodiment of the present invention will be described with reference to Figs. 1 to 3. An air gun for producing nonwoven fabrics 30 in this embodiment has a construction as shown in Fig. 1. The air gun 30 comprises an inlet 9a for receiving a filament 2 delivered from a spinning nozzle 1 shown in Fig. 3, an outlet 9e for delivering the filament 2 introduced from the inlet 9a, a compressed air inlet 11 and a compressed air blow port 10b, said compressed air blow port 10b being positioned in the periphery of the filament outlet 9e to blow out compressed air from the outlet 10b, and further comprises an air nozzle 3 for delivering a filament from the filament outlet 9e while drawing it, a connection pipe 12 connected on the side of the outlet 9e of the air nozzle 3 and an accelerating pipe 4 connected to the connection pipe 12 to guide and deliver the filament 2. A carrier path 20 for carrying the filament 2 is formed passing through the outlet 9e, the connection pipe 12 and an accelerating pipe 4 from the inlet 9a of the air nozzle 3. An exhaust path 13 is formed in the connection pipe 12. This embodiment will be described hereinafter in more detail. There are provided an air nozzle 3 for receiving a filament 2 spun from a spinneret 1 which is a collective body of spinning nozzles, an accelerating pipe 4 connected to the air nozzle 3 through a connection pipe 12, and a guide tube 5 connected to an extreme end of the accelerating pipe 4. Connected to the extreme end of the guide tube 5 is a separator nozzle (not shown) for scattering the filament 2 delivered together with compressed air toward a screen belt 6. The filament 2 scattered by the separator nozzle is accumulated on the screen belt 6 to form a web. The spinneret 1 as the collective body of spinning nozzles comprises nine sets each consisting of 108 small holes each having a diameter of 0.85 mm per section, and spinning is accomplished with molten resin extruded out of an extruder 1a. As shown in Fig. 1, the air nozzle 3 is composed of a first nozzle 9, and second nozzle 10 connected to the first nozzle 9. The first nozzle 9 has a filament inlet 9a for receiving the filament 2 delivered from the spinneret 1, and the interior continuous to the filament inlet 9a includes a tapered pipeline 9b reduced in diameter to a middle portion toward the extreme end and a straight pipeline 9c having the same diameter from the extreme end of the tapered pipeline 9b to a filament outlet 9e. This straight pipeline 9c is formed from a nozzle pipe 9d which is projected. The second nozzle 10 is connected to the first nozzle 9 so as to encircle the periphery of the extreme end of the nozzle pipe 9d. The second nozzle 10 has a blow nozzle 10a which encircles the extreme end of the nozzle pipe 9d. A slight clearance is formed between the inner surface of the blow nozzle 10a and the outer surface of the nozzle pipe 9d to form a compressed air blow port 10b around the filament outlet 9e at the extreme end of the nozzle pipe 9d. The inner surface of the blow nozzle 10a is gradually reduced in diameter from the air inlet 10c, is gradually increased in diameter behind the maximum constriction 10d in the midst, and thereafter assumes a straight pipeline having the same diameter from a portion corresponding to the filament outlet 9e. On the other hand, a compressed air inlet 11 is provided on the side of the second nozzle 10, said compressed air inlet 11 being communicated with the air inlet 10c of the blow nozzle 10a. Air introduced from the compressed air inlet 11 into the blow nozzle 10a increases its flow velocity the the maximum at a point passing through the maximum constriction 10d of the minimum inside diameter, whereby air is jetted strongly in a direction as indicated by arrow F from the compressed air blow port 10b to strongly draw the filament 2 passing near the center of the nozzle pipe 9d. A connection pipe 12 is connected to the second nozzle 10 in a direction of delivering the filament 2, an accelerating pipe 4 for guiding the filament 2 is connected to the connection pipe 12, and a guide tube 5 is connected to the extreme end of the accelerating pipe 4. The connection pipe 12 is formed with an exhaust path 13, said exhaust path 13 extending to be inverted at an angle 30 degrees (ϑ) with respect to the axial direction of the connection pipe 12 from an exhaust port 13a opened to the inner surface of the connection pipe 12 to the upstream side of air (upstream side the carrier path) and continuous to an air reservoir 13b. A closing valve 14 is provided in the midst of the exhaust path 13 continuous to the air reservoir 13b to open and close the exhaust path 13. In Fig. 2, the second connection pipe 12b is connected to the first connection pipe 12a, the connection pipe 12a being formed with the exhaust path 13, and the accelerating pipe 4 is connected at the second connection pipe 12b. The angle ϑ extended from the exhaust port 13a so that the exhaust path 13 is inverted toward the upstream with respect to the carrier path 20 is preferably 15 to 75 degrees. While the clearance of the exhaust port 13a used is 1mm, it is to be noted that a clearance in the range from 0.5 mm to 2.0 mm is preferred. In this way, the amount of drive air can be reduced and the receiving performance can be maintained without the filament being caught in the exhaust port 13a. The accelerating pipe 4 used has 6mm ⊘ of inside diameter and 540 mm of length. The guide tube 5 is provided to guide the filament 2 to the separator nozzle not shown, and the separator nozzle is connected to the extreme end of the guide tube 5. The separator nozzle is provided to scatter the filament 2 delivered together with the compressed air from the accelerating pipe 4 toward the screen belt 6. The air gun for producing nonwoven fabrics 30 constructed as described above was used and the exhaust path 13 was opened and closed to measure the amount of drive air, a degree of vacuum at the filament inlet 9a, the suction amount of air at the filament inlet 9a and the readiness of introduction of the filament 2 into the filament inlet 9a. A nylon monofilament having 520 µm of diameter was inserted by 700 mm into the air gun from the filament inlet 9a and tension applied thereto was measured. The results are shown in Table 1. In Table 1 above, units of the amount of air escape, amount of drive air, and suction amount of inlet are Nm³/hr respectively, and that of degree of vacuum is mmHg. Symbol " ○" indicate 'better', and "X" indicate 'difficult'. As will be apparent from Table 1, when the exhaust path 13 is opened, the traction (tension) with respect to the filament decreases but the degree of vacuum at the filament inlet 9a of the air gun and the suction amount of air increase, and the introduction of filament to the inlet 9a becomes easy. On the other hand, when the exhaust path 13 is closed, the degree of vacuum at the filament inlet 9a of the air gun 30 and the suction amount of air decrease and the introduction of filament to the inlet 9a is difficult but since all air flows into the accelerating pipe 4, the traction (tension) with respect to the filament increases. Accordingly, at the start of operation, when the filament is introduced into the air gun 30, the exhaust path 13 is opened to make the introduction of filament easy. When the filament is drawn after once being introduced, the exhaust path 13 is closed to provide a state in which tension is large.

Claims: An air gun (30) for use in producing nonwoven fabrics comprising an inlet (9a) for receiving a filament (2), a carrier path (20) through which, in use, an air flow delivers said filament from said inlet, a compressed air blow port (10b) opening into said carrier path between the ends thereof to supply said air flow and an exhaust path (13) from said carrier path downstream from said compressed air blow port to remove a part of the air flow in the carrier path. An air gun according to claim 1 wherein said exhaust path may be selectively opened or closed. An air gun according to claim 1 or 2, wherein said carrier path comprises an outlet for delivering the filament introduced from said inlet, an air nozzle for drawing and delivering the filament from the outlet, a connection pipe connected to an outlet side of said air nozzle, and an accelerating pipe connected to said connection pipe to guide and deliver said filament, said air gun further comprising a compressed air inlet, said compressed air blow port being positioned in the periphery of said outlet and said exhaust path being formed in the connection pipe. An air gun according to claim 3, wherein said air nozzle comprises a first nozzle and a second nozzle connected to said first nozzle, said first nozzle having a filament inlet for receiving a filament , the interior of said filament inlet including a tapered pipeline section reduced in diameter at a middle portion and a straight pipeline section having the same diameter as the smallest end of the tapered pipeline section along its entire length to the filament outlet, said straight pipeline section being within a projecting nozzle pipe, said second nozzle being connected to the first nozzle so as to encircle the periphery of the extreme end of the nozzle pipe, said second nozzle having a blow nozzle encircling said extreme end, a slight clearance being formed between the inner surface of said blow nozzle and the outer surface of said nozzle pipe, said clearance forming said compressed air blow port in the periphery of the filament outlet at the extreme end of the nozzle pipe. An air gun according to claim 4 wherein the inner surface of the blow nozzle is gradually reduced in diameter from the air inlet side, is then gradually increased in diameter behind the maximum constriction portion in the midst thereof and assumes a straight pipeline having the same diameter from a portion corresponding to the filament outlet, and wherein a compressed air inlet is provided on the side of the second nozzle, said compressed air inlet being communicated with an air inlet of the blow nozzle, and air introduced into the blow nozzle from the compressed air inlet increases its flow velocity to the maximum at a time passing through the maximum constriction portion of the minimum inside diameter whereby air is jetted strongly from the compressed air blow port so as to strongly draw the filament passing near the centre of the nozzle pipe, said connection pipe is connected to the second nozzle in a direction of delivering the filament. An air gun according to claim 3, 4 or 5 wherein a guide tube is connected to said connection pipe. An air gun according to any preceding claim, wherein said exhaust path crosses at an angle of 15 to 75 degrees with respect to said carrier path and extends from an exhaust port toward upstream of the carrier path. An air gun for producing nonwoven fabrics according to claim 7, wherein a clearance of the exhaust port opened to the carrier path of said exhaust path is in the range of 0.5 mm to 2.0 mm. An air gun for producing nonwoven fabrics according to any preceding claim, wherein a closable valve is connected to said exhaust path so as to selectively open and close the exhaust path. An air gun for producing nonwoven fabrics according to any preceding claim, wherein an air reservoir is connected to said exhaust path so that air from the exhaust path is discharged through the air reservoir. A control method for an air gun for use in producing nonwoven fabrics comprising an inlet for receiving a filament a carrier path through which in use an air flow delivers said filament from said inlet, a compressed air blow port opened in the midst of said carrier path to supply said airflow and an exhaust path in said carrier path downstream from said compressed air blow port, wherein when the filament spun from the spinning nozzle is being introduced into the inlet of said air gun, a part of the air flowing into the carrier path is discharged through said exhaust path. A control method according to claim 11, wherein air is discharged toward the upstream side of the carrier path with the exhaust direction from said exhaust path set to an angle of 15 to 75 degrees with respect to said carrier path. A control method according to claim 11 or 12 wherein once the filament has been introduced into the inlet of the air gun the exhaust path is closed.

Inventors: HAMASUNA HIROYUKI, HIGASHIYA NOBUO, KANEKO AKIRA, HAMASUNA, HIROYUKI, HIGASHIYA, NOBUO, KANEKO, AKIRA
Applicants: MITSUI PETROCHEMICAL IND, MITSUI PETROCHEMICAL INDUSTRIES, LTD.
Application year: 1991
Main classification: D04H3
IPC codes: D01H5, D04H3, D02J1, D02G1