JP5655020B2 - Thin-walled tube manufacturing method, tube manufactured by the manufacturing method, and multilayer structure tube - Google Patents

Description

The present invention relates to a method for manufacturing a thin-walled tube, a tube manufactured by the manufacturing method, and a multilayer structure tube.

  Conventionally, in the production of a thermoplastic resin tube, two methods were mainly employed: a hollow molding method and a tube production method by drawing a core material.

  The hollow molding method is a method in which the molten resin tube that has come out of the die is molded in a hollow shape, but the high-temperature molten resin tube immediately after coming out of the die is extremely deformable, and the tube to be molded is thin. Was easily deformed because the molded product floated in the cooling water tank or was crushed by water pressure. As a method for solving this problem, for example, a vacuum sizing method or an internal pressure method has been used (see Patent Document 1). However, the vacuum sizing method is suitable for forming a thick tube or a tube using a relatively hard resin. For example, when forming a thin tube having a wall thickness of 0.1 mm or less, the inlet of the vacuum cooling water tank is used. As a result, the tube stretched, making it difficult to mold. Also, in the internal pressure method, air is blown into the tube immediately after extrusion to apply internal pressure, so if the tube is thin, does the tube expand or burst before entering the cooling water tank? The mold could not be stably formed because it was crushed due to water pressure in the water tank. Furthermore, in the hollow molding method, a thin tube having a large outer diameter is easy to kink, so it is necessary to handle it with a large bending radius, and it is necessary to increase the radius of the guide roll part and the winding part of the production equipment. The handling was also difficult.

  On the other hand, the tube manufacturing method by drawing the core material is a method for solving the above-mentioned problems and manufacturing a thin and thin tube, for example, by using a copper wire as the core material and extruding or coating the outer periphery of the core material. A method of forming a resin coating layer and then pulling out a core material to manufacture a tube has been conventionally known (see Patent Document 2 and Patent Document 3). Conventionally, the core material used for manufacturing a tube by this method has been generally a silver-plated or tin-plated copper wire. The copper wire is soft and stretches with a low load and has a reduced diameter. Therefore, the copper wire is easy to pull out and easily pulled out by manpower. Also, since the copper wire is soft, it is easy to produce straightness and is suitable as a core material for manufacturing a tube. However, since copper is unstable and easily oxidized, and oxidized copper is easily peeled off, if the core material is used as it is, oxidized copper may adhere to the inner surface of the coating layer that is a resin. In order to prevent this, silver plating or tin plating is performed. However, it has the following problems. This core material is coated with the resin that makes up the tube, so it is necessary to use a resin or metal that has a heat resistance higher than the temperature at that time. It was necessary to prepare a core material, and the cost was high. Further, since the core material is thick, the diameter for pulling out is not easy and the workability is lowered. Furthermore, a core material feeder (supply) that handles a thick core material needs to be specialized.

Japanese Utility Model Publication No. 7-33624 Japanese Patent Laid-Open No. 5-15601 JP-A-9-285545

  However, the conventional tube manufacturing method by drawing the core material is a manufacturing method suitable for a thin and thin tube, and the core material is expensive when manufacturing a thin and large tube. Due to the increase in unit price and the thick core material, there is a problem that the diameter for pulling out is not easy and the workability is lowered. In addition, a core material feeder (supply), a take-up machine, and the like suitable for a thick core material are required, resulting in a problem of high costs.

Accordingly, an object of the present invention is to provide a method of manufacturing a thin-walled tube capable of manufacturing an inexpensive thin-walled and large-diameter tube with good dimensional accuracy, a tube manufactured by the manufacturing method, and a multilayer structure tube. .

[1] In order to achieve the above object, the present invention provides a hollow or rod-shaped inner resin layer made of a thermoplastic resin and a thermoplastic resin that is disposed on the outer periphery of the inner resin layer and does not adhere to the inner resin layer. An extrusion process for simultaneously extruding a tube intermediate composed of an outer resin layer made of resin, and the tube intermediate formed by the extrusion molding process in the direction of extrusion molding, and the cut tube A drawing step of drawing a thin tube having a thickness of the outer resin layer of 0.1 mm or less by pulling out the inner resin layer from the intermediate and separating the outer resin layer . A manufacturing method is provided.

[2] The outer resin layer is composed of an intermediate resin layer made of a thermoplastic resin that is not in close contact with the inner resin layer and an outermost resin layer made of a thermoplastic resin that is in close contact with the outer periphery of the intermediate resin layer. The method for producing a thin-walled tube according to the above [1], characterized in that

[3] A tube manufactured by the method for manufacturing a thin-walled tube described in [1] above may be used.

[4] A multilayer tube manufactured by the method for manufacturing a thin tube described in [2] may be used.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the thin wall tube which can manufacture a thin tube with a thin dimensional with good dimensional accuracy, the tube manufactured by the manufacturing method, and a multilayer structure tube can be provided.

FIG. 1 is a cross-sectional view of a tube intermediate according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view of the tube intermediate according to the second embodiment of the present invention. FIG. 3 is a cross-sectional view of the multilayer tube intermediate according to the third embodiment of the present invention. 4 is a cross-sectional view of a tube according to Comparative Example 1. FIG. FIG. 5 is a cross-sectional view of a tube according to Comparative Example 2. FIG. 6 is a diagram showing a list showing superiority or inferiority of each item in Examples 1, 2, and 3 and Comparative Examples 1 and 2. 7A and 7B show application example 1, and FIGS. 7C and 7D show application example 2. FIG.

[Embodiments of the present invention]
(First embodiment)
A method for manufacturing a thin-walled tube (hereinafter simply referred to as “tube”) according to the first embodiment of the present invention includes a hollow or rod-shaped inner resin layer 100 made of a thermoplastic resin, and an outer periphery of the inner resin layer 100. An extrusion process for simultaneously extruding a tube intermediate body 300 composed of an outer resin layer 200 made of a thermoplastic resin that is disposed on the inner resin layer 100 and is not in close contact with the inner resin layer 100, and a tube intermediate formed by this extrusion process A drawing step of cutting the tube 300 in the direction of extrusion and drawing the inner resin layer 100 from the cut tube intermediate 300 to separate the outer resin layer 200 to form the tube 200A. Yes.

  The outer resin layer 200 manufactured by this tube manufacturing method, that is, separated by pulling out the inner resin layer 100 from the tube intermediate 300 is a tube 200A. In addition, cutting in the direction of extrusion molding means cutting the inner resin layer 100 from the tube intermediate 300 in addition to cutting the tube intermediate 300 extruded into a long shape into a predetermined tube length and finishing it. It includes the case of cutting to a length that can be pulled out and separated. That is, it is possible to separate the outer resin layer 200 by pulling out the inner resin layer 100 from the tube intermediate 300 and cut the outer resin layer 200 into a predetermined tube length to form the tube 200A.

  In the above-described tube manufacturing method, when the inner resin layer 100 is hollow, pressurized air is introduced into the tube intermediate 300 from the head during the formation of the tube intermediate 300 in order to secure an inner diameter. Is preferred.

(Second Embodiment)
Although the first embodiment is a method for manufacturing a single-layer tube, the method for manufacturing a tube according to the second embodiment of the present invention is a method for manufacturing a multilayer structure tube.

  The outer resin layer 400 includes an intermediate resin layer 410 made of a thermoplastic resin that does not adhere to the inner resin layer 100 and an outermost resin layer 420 made of a thermoplastic resin that adheres to the outer periphery of the intermediate resin layer 410.

  In the second embodiment, a hollow or rod-shaped inner resin layer 100 made of a thermoplastic resin and a thermoplastic resin that is arranged on the outer periphery of the inner resin layer 100 and does not adhere to the inner resin layer 100 in the extrusion process. A tube intermediate body 500 composed of an intermediate resin layer 410 and an outermost resin layer 420 made of a thermoplastic resin that is in close contact with the outer periphery of the intermediate resin layer 410 is simultaneously extruded.

  The drawing process is the same as that of the first embodiment, and the tube intermediate body 500 formed by the extrusion molding process is cut in the direction of extrusion molding, and the inner resin layer 100 is drawn from the cut tube intermediate body 500. A multilayer structure tube 400A is formed by separating the outer resin layer 400 formed in multiple layers.

  Also in the second embodiment, in the tube manufacturing method, when the inner resin layer 100 is hollow, in order to secure an inner diameter, compressed air is supplied from the head to the tube intermediate 500 when the tube intermediate 500 is formed. It is preferable to introduce into the mold.

Example 1
FIG. 1 is a cross-sectional view of a tube intermediate 300 according to the first embodiment of the present invention. Using a 30 mm / 20 mm crosshead type simultaneous two-layer extrusion molding machine, hollow integral molding was performed with the 30 mm side as the inner resin layer 100 and the 20 mm side as the outer resin layer 200. LDPE (Novatec YF30 (registered trademark)) is used for the inner resin layer 100 having an inner diameter of 5.0 mm and an outer diameter of 7 mm, and outer layer of 0.07 mm thick polyurethane (Pelecene 2363-90AE (registered trademark)) is used on the outer periphery. A resin layer 200 was obtained. The inner resin layer 100 is not limited to LDPE, and may be any resin that does not adhere to the outer resin layer 200 due to heat melting, and may be EVA, PP, HDPE, or the like. The wall thicknesses of the inner resin layer 100 and the outer resin layer 200 were controlled by the screw speed of an extruder of 30 mm and 20 mm, respectively. The inner diameter was ensured by introducing pressurized air (for example, 15 kPa as a gauge pressure) from the head into the tube when the tube intermediate was formed. After the extrusion molding, the tube intermediate 300 is cut to a length of 500 mm, the outer resin layer 200 at both ends is removed with a cable stripper, and the inner resin layer 100 is drawn after being stretched to have an inner diameter of 7 mm and a wall thickness of 0.07 mm ( A polyurethane tube (tube 200A) having an outer diameter of 7.14 mm was obtained.

(Example 2)
FIG. 2 is a cross-sectional view of the tube intermediate 300 according to the second embodiment of the present invention. Using a 30 mm / 20 mm crosshead type simultaneous two-layer extrusion molding machine, hollow integral molding was performed with the 30 mm side as the inner resin layer 100 and the 20 mm side as the outer resin layer 200. Low density polyethylene LDPE (UBEC150) is used for the inner resin layer 100 having an inner diameter of 3.0 mm and an outer diameter of 4.8 mm, and a nylon elastomer (Pebax 7033 (registered trademark)) having a wall thickness of 0.1 mm is used as the outer resin. Layer 200 was designated. The inner resin layer 100 is not limited to LDPE, but may be any resin that does not adhere to the outer resin layer 200 due to heat melting, and may be PVC, PP, HDPE, or the like. The wall thicknesses of the inner resin layer 100 and the outer resin layer 200 were controlled by the screw speed of an extruder of 30 mm and 20 mm, respectively. The inner diameter was ensured by introducing pressurized air (for example, 10 kPa by gauge pressure) from the head into the tube when the tube intermediate was formed. After extrusion molding, the tube intermediate 300 is cut to a length of 1000 mm, the outer resin layer 200 at both ends is removed with a cable stripper, and the inner resin layer 100 is drawn after being stretched to have an inner diameter of 4.8 mm and a wall thickness of 0.1 mm. A nylon elastomer tube (tube 200A) having an outer diameter of 5.0 mm was obtained.

Example 3
FIG. 3 is a cross-sectional view of the multilayer tube intermediate 500 according to the third embodiment of the present invention. Using a 30 mm / 20 mm / 20 mm crosshead type simultaneous three-layer extruder, the inner resin layer 100 is formed on the 30 mm side and the outer resin layer 400 is formed on the 20 mm / 20 mm side, and the inner diameter is 3.0 mm and the outer diameter is 4.8 mm. The inner resin layer 100 is made of LDPE (UBEC150), and the outer periphery thereof is made of a 0.04 mm thick nylon elastomer (Pebax 7033) as an intermediate resin layer 410, and the outer side is a 0.06 mm thick nylon elastomer. (Pebax 5533) was used as the outermost resin layer 420. The inner resin layer 100 is not limited to LDPE, and may be any resin that does not adhere to the intermediate resin layer 410 due to heat melting, and may be PVC, PP, HDPE, or the like. The thicknesses of the inner resin layer 100 and the outer resin layer 400 (the intermediate resin layer 410 and the outermost resin layer 420) were controlled by the screw speed of each extruder. The inner diameter was ensured by introducing pressurized air (for example, 10 kPa by gauge pressure) from the head into the tube when the tube intermediate was formed. After the extrusion molding, the tube intermediate 500 is cut to a length of 1000 mm, the outer resin layer 400 at both ends is removed with a cable stripper, and the inner resin layer 100 is drawn after being stretched to have an inner diameter of 4.8 mm and a wall thickness of 0.1 mm ( A nylon elastomer two-layer tube (multilayer structure tube 400A) having an outer diameter of 4.0 mm was obtained.

(Comparative Example 1)
4 is a cross-sectional view of a tube according to Comparative Example 1. FIG. Polyurethane 600 (Pelecene 2363-90AE) having an inner diameter of 7.0 mm and a wall thickness of 0.07 mm was tubing with a 30 mm crosshead type extruder. The wall thickness was controlled by the screw speed of the extruder. The inner diameter was secured by forming the tube by introducing pressurized air (for example, 2 kPa as a gauge pressure) from the head when the tube was formed. After forming (bending radius of about R250 mm), the tube internal pressure fluctuated, or the tube internal pressure fluctuated due to water pressure collapse in the cooling water tank, so that a stable structure could not be obtained.

(Comparative Example 2)
FIG. 5 is a cross-sectional view of a tube according to Comparative Example 2. A nylon elastomer 620 (Pebax 7033) having a thickness of 0.1 mm was formed on a tin-plated annealed copper wire 610 having a diameter of 4.8 mm by using a 30 mm crosshead extruder. After extrusion, the tube is cut at 1000 mm, the nylon elastomer 620 at both ends is removed with a cable stripper, and the tin-plated annealed copper wire 610 as the core is drawn and then drawn to an inner diameter of 4.8 mm and a wall thickness of 0.1 m (outside A nylon elastomer tube 620A having a diameter of 5.0 mm was obtained.

(Effects of the present embodiment)
FIG. 6 is a diagram showing a list showing superiority or inferiority of each item in Examples 1, 2, and 3 and Comparative Examples 1 and 2. Compared to Examples 1, 2, 3 and Comparative Examples 1 and 2, each item (molding accuracy, extrusion speed, cost, post-treatment) is excellent (3 points) and excellent (2 points). The score is evaluated as being inferior (1 point) or very inferior (0 point), and the total is the total evaluation. From these comparison results, Comparative Examples 1 and 2 have a very poor evaluation (0 points) in some items, whereas Examples 1, 2, and 3 are very good in all items. There is no evaluation which is inferior to (0 points). In addition, Examples 1, 2, and 3 are largely superior to Comparative Examples 1 and 2 in comprehensive evaluation.

According to the present embodiment, the following effects are obtained.
(1) By hollow forming, it can be formed by a conventional tube forming line without using a large incidental facility for a large-diameter core.
(2) In the above hollow molding, the inner resin layer 100 is made hollow, and pressurized air is introduced from the head into the tube intermediate 300 (tube intermediate 500) when the tube intermediate 300 (tube intermediate 500) is molded. By molding, it is possible to ensure the inner diameter more reliably.
(3) Unlike the tube manufacturing method by drawing the core material, the core material is not required and can be manufactured at low cost. For example, the cost of LDPE is much cheaper than that of φ4.8 tinned annealed copper wire in the core material used in the tube manufacturing method by drawing the core material.
(4) By integrally molding with the inner resin layer 100 as the core material, the thickness is secured, so that it is difficult to kink and is easy to handle, and sizing can also be applied by increasing the tensile strength.
(5) A plurality of resin layers are simultaneously formed on the outer periphery of the inner resin layer 100 serving as a core material to form an outer resin layer 400 (for example, the intermediate resin layer 410 and the outermost resin layer 420), whereby a thin and multilayer structure is obtained. A tube having a structure can be formed, and characteristics that cannot be achieved by a single-layer tube can be realized.

  As mentioned above, although embodiment of this invention was described, these embodiment is only an example and does not limit the invention which concerns on a claim. These novel embodiments can be implemented in various other forms, and various omissions, replacements, changes, and the like can be made without departing from the scope of the present invention. In addition, not all the combinations of features described in these embodiments are essential to the means for solving the problems of the invention. Furthermore, these embodiments are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  7A and 7B show application example 1, and FIGS. 7C and 7D show application example 2. FIG. In FIG. 7A, the inner resin layer 710 is formed into a strand shape, and the outer resin layer 720 is formed thereon. By removing the inner resin layer 710, a thin-walled and large-diameter tube as shown in FIG. 7 (b) is formed, a thin-walled and thick-tube manufacturing method, a tube manufactured by the manufacturing method, and It can be applied to multilayer structure tubes.

  Further, in FIG. 7C, on the hollow inner resin layer 730, an outer resin layer 740 having a stripe shape with different colors and hardness extruded with different resins 741 and 742 is formed. By removing 730, a thin and thick tube as shown in FIG. 7 (d) is formed. Stripe extrusion as described above and extrusion technology as a multilayer skin layer having a two-layer or three-layer structure are used as known technologies. By applying these extrusion technologies to the present invention, various thin walls can be obtained. The present invention can be applied to a method for producing a large-diameter tube, a tube produced by the production method, and a multilayer structure tube.

DESCRIPTION OF SYMBOLS 100 ... Inner layer resin layer 200 ... Outer layer resin layer 200A ... Tube 300 ... Tube intermediate body 400 ... Outer layer resin layer 400A ... Multilayer structure tube 410 ... Intermediate layer resin layer 420 ... Outermost layer resin layer 500 ... Tube intermediate member 600 ... Polyurethane 610 ... Tin-plated annealed copper wire 620 ... nylon elastomer 620A ... nylon elastomer tube

Claims (4)

A tube intermediate composed of a hollow or rod-shaped inner resin layer made of a thermoplastic resin and an outer resin layer made of a thermoplastic resin that is disposed on the outer periphery of the inner resin layer and does not adhere to the inner resin layer. An extrusion process to extrude at the same time;
The tube intermediate formed by the extrusion molding process is cut in the direction of extrusion, the inner resin layer is pulled out of the cut tube intermediate, and the outer resin layer is separated to thereby increase the thickness of the outer resin layer. A drawing step of forming a thin tube of 0.1 mm or less ;
A method for producing a thin-walled tube, comprising: The outer resin layer comprises an intermediate resin layer made of a thermoplastic resin that does not adhere to the inner resin layer, and an outermost resin layer made of a thermoplastic resin that adheres to the outer periphery of the intermediate resin layer. The method for producing a thin-walled tube according to claim 1. A tube manufactured by the method for manufacturing a thin-walled tube according to claim 1. A multi-layered tube manufactured by the method for manufacturing a thin-walled tube according to claim 2.

Images