JP2007245415A - Manufacturing method of drilled tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a drilled tube, which is excellent in the precision of width, the precision of a drilling diameter and the precision of a drilling position, at a high production speed without causing a non-supposed piercing phenomenon or surface damage phenomenon due to the arrival of a laser beam on the opposite side of the tube. <P>SOLUTION: A thermoplastic resin is subjected to extrusion molding from a cylindrical slit by a melt extrusion method to be cooled, the obtained tube is folded into a planar state by a pinch roll to be allowed to continuously run, a core equipped with a piercing hole in the direction crossing the planar part of the tube at a right angle is arranged in the folded tube to be held at a definite position by arranging a core fixing jig at least on the downstream side in the running direction of the folded tube with respect to the core and the laser beam is thrown on the folded tube from its one surface side toward the piercing hole of the core so as to be focused to one surface of the folded tube to drill the folded tube. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a perforated tube, and more specifically, industrially advantageous production of a perforated tube by combining a tube forming step of extruding a thermoplastic resin from a cylindrical slit by a melt extrusion method and a laser perforating step. Regarding the method. The perforated tube of the present invention is used for various applications including a watering tube in the agricultural field, for example.

  In recent years, water spray tubes made of thermoplastic resins such as polyethylene resins have been used in place of hard synthetic resin tubes for watering and irrigation mainly in the fields of agriculture and civil engineering. Usually, these watering tubes have a form in which a large number of small holes are regularly arranged with high accuracy by high-precision drilling processing. A uniform watering characteristic can be achieved by connecting a connected water supply pipe to a water source such as a pump and supplying the supplied water with a predetermined water pressure.

Conventionally, as one method of manufacturing a sprinkling tube, a thermoplastic resin is extruded from a cylindrical slit by a melt extrusion method, and the obtained cylindrical thermoplastic resin tube is irradiated with laser light to perform perforation. After that, a method of folding by a pinch roll and winding up as a folded tube has been proposed (see, for example, Patent Document 1).
JP-A-2-258187

  However, in the case of the above manufacturing method, high-precision tube internal pressure control is necessary to keep the tube width (diameter) constant, and high-quality water spray tubes are manufactured in terms of drilling accuracy and width accuracy. Have difficulty.

  The present invention has been made in view of the above circumstances, and the purpose thereof is, for example, when used as a watering tube, an unexpected penetration due to the arrival of laser light on the opposite side of the tube, which is essentially unnecessary and should not be present. It is an object of the present invention to provide a perforated tube manufacturing method that is free from phenomena and surface damage phenomena and that has excellent width accuracy, perforation diameter accuracy and perforation position accuracy. Another object of the present invention is to provide a perforated tube manufacturing method having a high production rate.

  That is, the first gist of the present invention is to arrange a core having a through hole in a direction perpendicular to the flat portion of the tube inside the continuously traveling folding tube, and By placing a core fixing jig at least downstream in the running direction, the core is held in a fixed position, and from one side of the folding tube to the through hole of the core and on one side of the folding tube The present invention resides in a method for manufacturing a perforated tube, characterized in that perforation is performed by irradiating a laser beam in focus.

  And the second gist of the present invention is cooling after extruding a thermoplastic resin from a cylindrical slit by a melt extrusion method, and the obtained tube is folded into a plane by a pinch roll and continuously run, A core having a through hole in a direction perpendicular to the flat portion of the tube is disposed inside the folding tube, and a core fixing jig is disposed at least downstream in the traveling direction of the folding tube with respect to the core. The core is held in a fixed position by this, and perforation is performed from one side of the folding tube toward the through hole of the core and by irradiating laser light with focusing on one side of the folding tube. In the manufacturing method of a perforated tube.

  According to the present invention, the tube folding width does not fluctuate with time and the width accuracy is good, and a large number of perforations are regularly arranged on the laser beam irradiation tube surface side with high accuracy, and the laser beam is on the opposite side of the tube There is provided a method of manufacturing a perforated tube that is free from unexpected penetration and surface damage due to arrival, and that can be molded, picked up, and conveyed at high speed.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is an overall explanatory view of an example of a preferred embodiment of the present invention according to the second aspect of the present invention, and FIG. 2 is an explanatory view of a main part of the embodiment shown in FIG.

  First, for convenience of explanation, the invention according to the second aspect of the present invention will be described. The present invention includes a tube forming step of extruding a thermoplastic resin from a cylindrical slit by a melt extrusion method. Such a tube forming step can be performed using the same equipment as in the so-called inflation method. As a constituent material of the perforated tube, a thermoplastic resin is used as in the conventional method. As the thermoplastic resin, for example, polyolefin resin, vinyl resin, polyester resin, polyamide resin, or the like can be used. Among these, polyolefin resins are particularly preferable.

Examples of polyolefin resins include polyethylene, ethylene-α-olefin copolymers, ethylene-vinyl acetate copolymers, and mixtures of these resins. The density of polyethylene is usually 0.90 to 0.94 g / cm ³ , preferably 0.91 to 0.93 g / cm ³ , and the density of the ethylene-α-olefin copolymer is usually 0.90 to 0. 0.94 g / cm ³ , preferably 0.91 to 0.93 g / cm ³ . The content of vinyl acetate units in the ethylene-vinyl acetate copolymer is usually 1 to 20% by weight, preferably 3 to 15% by weight.

  When each density of polyethylene and ethylene-α-olefin copolymer is lower than the above range, the mechanical strength of the perforated tube is lowered, and durability, pressure resistance, and heat resistance may be inferior, and higher than the above range. If it is too high, the flexibility of the perforated tube may be impaired, which may hinder storage during storage, uniform water spraying during watering, and handling convenience. Moreover, when there is more content of the vinyl acetate unit of an ethylene-vinyl acetate copolymer than said range, the mechanical strength of a perforated tube will become low and durability, pressure resistance, and heat resistance may be inferior.

  Examples of the α-olefin used for the production of the ethylene-α-olefin copolymer resin include propylene, butene-1, hexene-1, 4-methylpentene-1, octene-1, and the like. As such, any of a polymerization method using a Ziegler catalyst or a polymerization method using a metallocene catalyst may be used.

  Further, the melt index (measurement method: conforming to JIS K7210, temperature: 190 ° C., load: 2160 g) of the above polyolefin resin is usually 0.1 to 50 g / 10 minutes, preferably 0.2 to 20 g / 10 minutes. It is. When the melt index is lower than the above range, the molten resin at the time of extrusion processing is too high in viscosity, resulting in poor extrusion processability and may cause poor appearance of the obtained tube surface. On the other hand, when the melt index is higher than the above range, it is difficult to obtain stable molding processability because the viscosity is too low, and the mechanical strength of the tube itself is lowered, resulting in inferior durability, pressure resistance, and heat resistance. is there.

  To the thermoplastic resin used in the present invention, carbon, a weather stabilizer, an antioxidant and the like can be appropriately added in advance for the purpose of improving the durability and weather resistance of the perforated tube. In addition, various additives such as inorganic fillers, lubricants, pigments, dyes, antistatic agents, and plasticizers can be appropriately added as necessary.

  In particular, by adding carbon black to the thermoplastic resin, when drilling with a YAG laser, which will be described later, the energy absorption in the near-infrared region can be improved, and the finish of the drilled part and the drilling can be improved. Speed can be greatly improved. The amount of carbon black added is usually 0.5 to 6 parts by weight with respect to 100 parts by weight of the thermoplastic resin.

  In this invention, a tube formation process cools, after extruding a thermoplastic resin from a cylindrical slit by a melt extrusion method, folds the obtained tube flatly with a pinch roll, and runs continuously.

  The winding direction of the tube folded flat by a pinch roll may be any of the upper, horizontal, and lower directions. Moreover, although the cooling method of the cylindrical thermoplastic resin tube extruded from the annular die includes an air cooling type and a water cooling type, any method may be used in the present invention.

  However, from the viewpoint of manufacturing a perforated tube having excellent width accuracy, perforation diameter accuracy, and perforation position accuracy at a high speed, a water cooling type as shown in FIG. 1 is recommended. The water-cooled tube forming step mainly includes an extruder (1), an annular die (11), a water tank (2) disposed below the annular die (11) and provided with a size ring (not shown) inside, Made of a cylindrical thermoplastic resin extruded from an annular die (11) through an extruder (1) using equipment comprising a guide plate (3) and a pinch roll (41) disposed below the water tank After the tube (8) is guided to the water tank (2) and cooled, it is supplied to the pinch roll (41) through the guide plate (3), folded, and wound as a folded tube (9) on the winding roll (5). is there. In FIG. 1, symbols (42), (43) and (46) are tension rolls, and other symbols will be described later.

  The feature of the present invention resides in the perforation process. As shown in FIG. 1, a core (7) having a through hole (71) in a direction perpendicular to the flat portion of the tube is provided inside the folding tube (9). The core (7) is held at a fixed position by disposing a core fixing jig at least downstream in the traveling direction of the folding tube (9) with respect to the core (7), and then folded. Perforation is performed by irradiating laser light from one side of the tube (9) toward the through hole (71) of the core and focusing on one side of the folded tube. According to such a method, only one side of the folding tube on which the laser beam is focused is perforated, and the other side of the folding tube is energized by shifting the focal point of the laser beam by an amount corresponding to the thickness of the core (7). Not perforated to damp.

  In the preferred embodiment shown in FIG. 1, a pinch roll (45) is used as the core fixing jig, and the core fixing pinch roll (44) is also arranged upstream of the folding tube (9) in the traveling direction. By doing so, the fixed position maintenance of the core (7) arrange | positioned inside the folding tube (9) is made more reliable. The core fixing pinch rolls (44) and (45) may be either a drive roll type or a free roll type. In this invention, it replaces with said pinch roll (45) as a jig | tool for core fixing, For example, plate shape of the substantially same width as a folding tube from the diagonal direction of a folding tube so that a movement of a core may be stopped. The core can be held at a fixed position by bringing the member into contact with the core. Further, the laser beam irradiation device (6) is preferably arranged so that the laser beam irradiation direction is substantially perpendicular to the transported tube as shown in FIG.

  In the present invention, the material of the core (7) is not particularly limited, but a fluororesin or a silicone resin is preferable from the viewpoint of reducing the frictional resistance with the inner surface of the tube. The thickness of the core (7) is usually 1 mm or more, preferably 3 mm or more, and the upper limit is usually 20 mm. In addition, when the thickness of the core (7) is too thin, both sides of the folding tube may be perforated. The through hole (71) is usually provided in the approximate center of the core (7). And the magnitude | size is made into an appropriate magnitude | size which a tube does not bend in a through-hole (the flatness of a tube is not impaired). The material of the core (7) may be an inorganic material, and the inorganic material can be used alone or coated with the above resin.

  Specific examples of the fluorine resin include polytetrafluoroethylene (Teflon (registered trademark)), tetrafluoroethylene-hexafluoropropylene copolymer, polychlorotrifluoroethylene, tetrafluoroethylene-ethylene copolymer, polyvinyl Fluoride, polyvinylidene fluoride and the like can be mentioned, and specific examples of the silicone resin include dimethylpolysiloxane, methylphenylpolysiloxane, diphenylpolysiloxane and the like.

  In the present invention, the laser beam irradiating device (6) substantially has a structure in which excitation light is condensed on an exciter formed by YAG, carbon dioxide gas, or other methods, and near infrared rays are emitted from the exciter. Any laser light generator may be used. Among these, a laser beam irradiation device (including a recent laser marker device) using a YAG laser or a carbon dioxide laser is preferable.

  When using a YAG laser, especially YAG laser processing equipment with a relatively high output of an average output exceeding 50 to 100 W, drilling with high-energy laser light is performed, and as a result, the drilled part has a sharp finish. There is no molten resin swell phenomenon, and uniform and well-shaped perforations can be obtained. In addition, when a laser marker device found in recent carbon dioxide lasers and YAG lasers is used, it is possible to design a drill with a relatively high degree of freedom while using a low-energy laser beam with an average output of 10 to 50 W class. .

  In the present invention, as shown in FIG. 2, it is preferable to arrange the pressing roll (47) in contact with the outer surface of the portion where the core (7) of the folding tube (tube) (9) is located. Such a pressing roll (47) prevents fine movement of the folding tube (tube) (9) with respect to the laser beam irradiation device (6), and a target perforation diameter is always obtained while maintaining a constant focal irradiation distance. . In the preferred embodiment shown in FIG. 2, two sets of pressing rolls (47) are arranged before and after the folding tube in order to prevent the above-mentioned fine movement more reliably. A pressing plate can be used instead of the illustrated pressing roll. In FIG. 2, reference numeral (71) denotes a core body, and (72) denotes a covering portion.

  In the present invention, the thickness of the perforated tube is usually 0.1 to 1.0 mm, preferably 0.2 to 0.8 mm, and the folding diameter is usually 10 to 100 mm, preferably 20 to 80 mm. Moreover, the perforation diameter, perforation interval, and perforation row number of the perforated tube can be appropriately selected. As an example thereof, there may be mentioned perforation diameter: 0.1 to 1.0 mm, perforation interval: 10 to 500 mm, perforation row number: 1 to 20 row, and the like.

  Next, the invention according to the first aspect of the present invention will be described. In the present invention, a core having a through hole in a direction perpendicular to the flat portion of the tube is disposed inside the continuously traveling folding tube, and at least downstream in the traveling direction of the folding tube with respect to the core. By placing a core fixing jig on the core, the core is held at a fixed position, and the laser beam is focused from one side of the folding tube toward the through hole of the core and on one side of the folding tube. It is characterized by performing perforation by irradiating. That is, the invention according to the first aspect of the present invention differs from the invention according to the second aspect in that it is not necessary to continuously perform the tube forming step and the perforating step.

  In the invention according to the first aspect of the present invention, the continuously running folding tube can be performed according to the above-described method using the same equipment as in the so-called inflation method. The obtained folded tube is taken up by a take-up roll, and then sent to a perforating process to be used for manufacturing a perforated tube.

  The perforated tube obtained by the present invention is preferably used as a watering tube in the agricultural field, for example, but can also be used as a carbon dioxide discharge tube in a house, and further, a liquid fertilizer supply tube Etc. can also be used.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded.

Example 1:
(1) Polyolefin resin composition comprising 97 parts by weight of a high pressure polymerization polyethylene resin having a melt index of 1 g / 10 min and a density of 0.92 g / cm ³ and 3 parts by weight of carbon black as a constituent material of a perforated tube (A) was used.

(2) As a core, a rectangular shape having a side of 43 mm in the width direction and a side of 15 mm in the length direction at a substantially center of a Teflon (registered trademark) plate having a width of 53 mm, a length of 180 m, and a thickness of 5 mm. A core with a through hole was used.

(3) A YAG method (with irradiation scanning function) device having an average output of 300 W was used as the laser beam irradiation device.

  A perforated tube manufacturing method was performed according to the procedure shown in FIGS. The polyolefin-based resin composition (A) has a melt extrusion temperature of 160 ° C., a tubular thermoplastic resin tube (8) having a wall thickness of 0.50 mm and a tube diameter of 39 mm is produced, led to the water tank (2), and cooled. Then, it was supplied to the pinch roll (41) through the guide plate (3), folded (folded diameter: 62 mm), and continuously run as a folded tube (9) at a conveyance speed of 15 m / min.

  Then, the core (7) is disposed inside the tube (9) that is folded by the pinch roll (41) and is continuously running, and the core is placed before and after the running direction of the tube with respect to the core (7). The fixing pinch rolls (44) and (45) were arranged to hold the core (7) in a fixed position while sliding. Then, drilling was performed by irradiating laser light from one side of the folding tube (9) toward the through hole (71) of the core (7) and focusing on one side of the folding tube. At this time, the laser irradiation energy, the irradiation position, and the irradiation timing were appropriately set so that a predetermined drilling design with a 50 mm drilling interval in a 10-row arrangement with a drilling diameter of 0.30 to 0.50 mm was obtained. The obtained perforated tube was wound up by a winding roll (5) to obtain a product.

  The above-mentioned perforated tube is free of blocking and fusing phenomenon due to insufficient cooling, has good width accuracy, and is stably manufactured under high speed conditions of take-up / conveyance speed of 15 m / min. The part has a hole diameter of 0.30, 0.35, 0.40, 0.45, 0.50 mmΦ as specified, and is a perfect circle with no distortion of the peripheral part or resin melt-up phenomenon, Moreover, there was no unexpected penetration phenomenon or surface damage phenomenon due to the arrival of the laser beam on the opposite side of the tube, and the width accuracy, drilling diameter accuracy, and drilling position accuracy were excellent.

Comparative Example 1:
In Example 1, the use of the core (7) is stopped, and the folded tube (9) that is folded by the pinch roll (41) and continuously running is subjected to laser drilling processing under predetermined setting conditions, and the rolled tube product Manufactured. As a result, the obtained perforated tube showed unexpected penetration and surface damage due to the arrival of laser light on the opposite side of the tube, which hinders the water spraying performance and durability of the tube when used as an actual perforated tube. I came. The other points were the same as in Example 1.

Comparative Example 2:
A tube forming process using both an air cooling device and an internal cooling mandrel contact cooling device was adopted, and a perforated tube was manufactured in the following manner.

  As a constituent material of the perforated tube, a polyolefin resin composition (A) having the same composition as that used in Example 1 was used, and a tubular thermoplastic resin tube (thickness 0. 50 mm, tube diameter 39 mm) was obtained, laser drilling was performed under predetermined setting conditions until reaching the pinch roll, and then the product was folded by a pinch roll and wound by a take-up roll (5). In this case, when the take-up / transport speed was 5 m / min, there was no fluctuation in the tube diameter, and a stable perforated tube with excellent target width accuracy, drilling diameter accuracy, and drilling position accuracy was obtained. When manufacturing at a high speed with the speed increased to 8 m / min or more, the tube cooling / solidification is not in time, and the tube diameter fluctuates immediately, achieving the desired width accuracy, drilling diameter accuracy, and drilling position accuracy. An excellent perforated tube could not be produced at high speed.

Overall explanatory diagram of an example of a preferred embodiment of the present invention according to the second aspect of the present invention Explanatory drawing of the principal part of the embodiment shown in FIG.

Explanation of symbols

1: Extruder 11: Circular die 2: Water tank 3: Guide plate 41: Pinch roll 42: Tension roll 43: Tension roll 44: Pinch roll 45: Pinch roll 46: Tension roll 47: Pressing roll 5: Winding roll 6: Laser beam irradiation device 7: Core 71: Through hole 8: Thermoplastic resin tube 9: Folding tube

Claims (5)

  A core with a through hole in the direction that goes straight to the flat part of the tube is placed inside the folding tube that runs continuously, and the core is fixed to the core at least downstream in the direction of travel of the folding tube. By holding the core in a fixed position by placing a jig, and irradiating laser light from one side of the folding tube toward the through hole of the core and focusing on one side of the folding tube The manufacturing method of the perforated tube characterized by performing perforation.   The thermoplastic resin is extruded from a cylindrical slit by a melt extrusion method and then cooled, and the obtained tube is folded into a flat shape by a pinch roll and continuously run, inside the folded tube, on the flat portion of the tube. Place the core with a through hole in the direction to go straight, hold the core in a fixed position by placing a core fixing jig at least downstream in the traveling direction of the folding tube relative to the core, And the manufacturing method of the perforated tube characterized by performing perforation by irradiating a laser beam focusing on the single side | surface of the said folding tube from the single side | surface side of a folding tube, and focusing on the one side of the said folding tube.   The manufacturing method according to claim 1 or 2, wherein the core fixing jig is a pair of rolls arranged above and below the folding tube.   The manufacturing method according to any one of claims 1 to 3, wherein the cooling is a water cooling type.   The manufacturing method in any one of Claims 1-4 in which the core is comprised from the fluorine resin or the silicone resin.