JP3779770B2 - Method for manufacturing flexible hose and hose - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a flexible hose manufacturing method and a hose, and more particularly to a flexible hose used when a chemical manufacturing plant or air, water or the like is sent.
[0002]
[Prior art]
Conventionally, the following technique is known as a method for obtaining a flexible hose having a corrugated surface.
[0003]
(1) For example, as disclosed in Japanese Patent Publication No. 42-24835, when a thermoplastic resin is melt-extruded, the resin is extruded into a corrugated mold and pressurized and cooled (prior art 1).
[0004]
(2) A method in which a melt-extruded thermoplastic resin hose is brought into contact with a corrugated mold, heated, pressurized and cooled to obtain a flexible hose (prior art 2).
[0005]
[Problems to be solved by the invention]
However, in the method according to the prior art 1, as shown in FIG. 5, in order to match the half molds 51a and 51b, the resin protrudes from the finished hose surface (part line generation), and the protruding part line is finished. There must be.
[0006]
Further, in the method according to the prior art 2, when the internal pressure is applied, the space between the hose outer surface and the mold is hermetically sealed. Therefore, a large number of vent holes 62 must be provided in the half mold 61 as shown in FIG. Don't be. In addition, due to the resin flow to the part line and the gas vent part, as in the case of the prior art 1, there may be problems such as part line residue, uneven thickness difference, and pinholes. Lack.
[0007]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a highly reliable flexible hose manufacturing method and hose that do not require post-finishing because there is no part line as in the prior art. And
[0008]
[Means for Solving the Problems]
The first invention of the present application includes a step of winding a spiral covering around at least a part of the outer periphery of the thermoplastic resin hose, a step of inserting the hose into the outer cylinder in this state, and both ends of the hose. A step of heat-softening the hose in a sealed state, a step of applying internal pressure from the inside of the hose, a step of cooling the hose and processing the surface of the hose into a spiral shape, and an outer periphery of the outer tube and the hose A step of removing the spiral covering body . The method of manufacturing a flexible hose having a spiral surface .
[0010]
A second invention of the present application is a flexible hose having a helical surface manufactured according to the first invention .
[0011]
In the present invention, the step of heat softening the hose and the step of applying the internal pressure from the inside of the hose may be simultaneous, or after the heat softening of the hose, the internal pressure may be applied from the inside of the hose, or The hose may be heated and softened immediately after the internal pressure is applied from the inside.
[0012]
In the present invention, examples of the thermoplastic resin include polyethylene resin, polypropylene resin, vinyl chloride resin, polyamide resin, and fluorine resin. Here, when a fluororesin such as PTFE or PFA is used, the temperature at which the hose is softened by heating is preferably 260 ° C. or higher in consideration of the melting point of PTFE or PFA. This is because if the internal pressure is applied to the inner side of the hose at a temperature lower than 260 ° C., the outer peripheral portion of the hose located between the coverings cannot be sufficiently expanded outward.
[0013]
In the present invention, the spiral covering is, for example, a wire or a wire having a spiral shape, and examples thereof include a commercially available spring. Examples of the cross-sectional shape of the covering include circular and elliptical shapes. Examples of the material of the covering include aluminum, iron, and stainless steel.
[0014]
In addition, the covering body regulates the pitch of the flexible hose, and has the above-described cross-sectional shape or is processed using a hollow material, but usually has a constant pitch. . However, you may use what changed the pitch.
[0015]
Furthermore, the said covering body may be wound over the outer periphery of the hose, may be wound in part, and should just be determined by the use of a hose. For example, in the case where a curved portion is known in advance, the hose may be made flexible by winding a covering around only that portion. Of course, it is possible to give flexibility to portions other than the portion.
[0016]
In the present invention, examples of means for softening the hose by heating include a method in which a band heater is wound around an outer cylinder as in the embodiment, a heating method in an electric furnace, and a heating method in a hot salt bath. .
[0017]
In the present invention, the relationship between the covering and the hose is such that the diameter of the covering is D and the distance from the inner wall surface of the outer cylinder to the valley of the outer peripheral surface of the hose is L, as shown in FIG. Ideally, D = distance L. However, the present invention is not necessarily limited to this, and the effect of the present invention can be expected even if the diameter D and the distance L are slightly different. Further, the outer cylinder so restricts the outer diameter of the hose, an inner diameter equal to or slightly larger in outer diameter D ₁ of the helical covering member attached to the hose.
[0018]
In the present invention, the relationship between the outer diameter of the covering and the outer diameter of the hose is as follows. The outer diameter of the covering is D ₁ , the outer diameter of the hose is D ₂ , and the alignment of the covering is d. For example, D ₂ = D ₁ -2d, but it is preferable to have a gap of about 0.05 to 0.2 mm between the hose and the cover in order to cover the cover with the hose.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below with reference to FIG.
[0020]
Example 1
First, a fine powder of polytetrafluoroethylene (PTFE) resin (trade name: Polyflon F302, manufactured by Daikin Industries, Ltd.) is infiltrated with a liquid lubricant, and then extruded into a hose shape having an inner diameter of 24 mm and a wall thickness of 2 mm. After obtaining a molded product, the liquid lubricant was removed and baked to obtain a PTFE hose 1 having an outer diameter of 28 mm and an inner diameter of 24 mm.
[0021]
Next, the hose 1 was inserted into an open-end stainless spring (cover) 2 having an inner diameter of 28.1 mm, a wire diameter of 3.5 mm, a pitch of 10 mm, and a length of 220 mm. Next, the hose 1 in a state where the spring 2 was wound was inserted into a stainless steel outer tube 3 having an inner diameter of 35.5 mm, an outer diameter of 50 mm, and a length of 200 mm. Subsequently, one end of the hose 1 was closed with a stainless steel sealing material 4, and the other end of the hose 1 was also sent to the hose 1 using a stainless steel sealing material 5 and a pipe 6 to increase the internal pressure.
[0022]
Next, the outer periphery of the outer cylinder 3 was covered with a band heater 7 and heated so that the temperature of the hose 1 was 380 ° C. and held at that temperature for 5 minutes. Then, simultaneously with turning off the band heater 7, 6 kg / cm ² of air was applied, and the band heater 7 covered with the outer cylinder was removed and cooled with water or air. The air pressure is applied until just before the outer cylinder 3 is removed.
[0023]
Next, when the temperature of the hose 1 was close to room temperature, the hose 1 wound with the spring 2 was removed from the outer cylinder 3. Next, the spring 2 was rotated in the direction opposite to the winding direction and removed from the hose 1 to obtain a flexible hose 8 as shown in FIG. The hose 1 used was about 200 mm longer than the length of the outer cylinder 3. Moreover, the number 9 in FIG. 1 is a pipe-shaped heat insulating material having heat resistance, and the material thereof is made of, for example, ceramics or metal.
[0024]
According to the first embodiment, the stainless steel spring 2 is wound around the outer periphery of the PTFE hose 1, and after inserting the hose 1 into the stainless steel outer cylinder 3 in this state, both ends of the hose 1 are sealed. The flexible hose is obtained by sending air to the inside of the hose 1 to apply internal pressure, cooling the hose 1 with water or air, and then removing the spring 2 on the outer periphery of the hose 1. Therefore, according to Example 1, there was no part line or pinhole as in the prior art, and a good wavy flexible hose was obtained. Further, according to Example 1, there was no need for post-finishing as in the prior art.
[0025]
(Example 2)
First, a polytetrafluoroethylene / perfluoroalkyl vinyl ether copolymer resin PFA (trade name: NEOFLON AP-230, manufactured by Daikin Industries, Ltd.) was used, and a hose 1 having an outer diameter of 29 mm and an inner diameter of 26 mm was obtained using a melt extruder. Manufactured. The hose 1 was inserted into an open-end stainless steel spring having an inner diameter of 29.1 mm, a wire diameter of 3.5 mm, a pitch of 10 mm, and a length of 220 mm.
[0026]
Next, the hose 1 in a state where the spring was wound was inserted into a stainless steel outer tube 3 having an inner diameter of 36.5 mm, an outer diameter of 50 mm, and a length of 200 mm. Subsequently, one end of the hose was closed with the sealing material 4 and the other end of the hose 1 was also sent to the hose 1 using the sealing material 5 and the pipe 6 so that the internal pressure could be raised.
[0027]
Next, the outer periphery of the outer cylinder 3 was covered with a band heater 7 and heated so that the temperature of the hose 1 was 315 ° C. Here, when heating is performed, the hose internal pressure is adjusted to be maintained at 500 mmAq until the hose temperature reaches 300 ° C. After the hose temperature reaches 315 ° C, the hose temperature is maintained for 1 minute, The pressure was increased to 1000 mmAq. Thereafter, the heater was turned off, the band heater 7 covered on the outer cylinder was removed, and cooled with water or air. The air pressure is applied until just before the outer cylinder 3 is removed.
[0028]
Next, when the temperature of the hose 1 was close to room temperature, the hose 1 wound with the spring 2 was removed from the outer cylinder 3. Next, the spring 2 was rotated in the direction opposite to the winding direction and removed from the hose 1. The hose 1 used was about 200 mm longer than the length of the outer cylinder 3.
[0029]
According to Example 2, as in Example 1, a good wavy flexible hose that did not require post-finishing was obtained.
[0030]
Example 3
First, a polytetrafluoroethylene / perfluoroalkyl vinyl ether copolymer resin PFA (trade name: NEOFLON AP-230, manufactured by Daikin Industries, Ltd.) was used, and a hose 1 having an outer diameter of 29 mm and an inner diameter of 26 mm was obtained using a melt extruder. Manufactured. The hose 1 was inserted into an open-end stainless steel spring having an inner diameter of 29.1 mm, a wire diameter of 3.5 mm, a pitch of 10 mm, and a length of 220 mm.
[0031]
Next, the hose 1 in a state where the spring was wound was inserted into a stainless steel outer tube 3 having an inner diameter of 36.5 mm, an outer diameter of 50 mm, and a length of 200 mm. Subsequently, one end of the hose was closed with the sealing material 4 and the other end of the hose 1 was also sent to the hose 1 using the sealing material 5 and the pipe 6 so that the internal pressure could be raised.
[0032]
Next, the outer periphery of the outer cylinder 3 was covered with a band heater 7 and heated so that the temperature of the hose 1 was 290 ° C. and held at that temperature for 5 minutes. Thereafter, simultaneously with turning off the band heater 7, 10 kg / cm ² of air was applied, and the band heater 7 covered with the outer cylinder was further removed and cooled with water or air. The air pressure is applied until just before the outer cylinder 3 is removed.
[0033]
Next, when the temperature of the hose 1 was close to room temperature, the hose 1 wound with the spring 2 was removed from the outer cylinder 3. Next, the spring 2 was rotated in the direction opposite to the winding direction and removed from the hose 1. The hose 1 used was about 200 mm longer than the length of the outer cylinder 3.
[0034]
According to Example 3, as in Example 1, a good wavy flexible hose that did not require post-finishing was obtained.
[0035]
In each of the above embodiments, the case where the spring is removed after the hose has been cooled has been described. However, the present invention is not limited to this, and the spring may be left as it is to serve as a reinforcing material. The hose obtained in this way is useful when feeding a material that does not erode the spring, such as water or air. Moreover, since it is not necessary to remove a spring like this embodiment, such a hose can reduce the manufacturing process.
[0036]
【The invention's effect】
As described in detail above, according to the present invention, there is no part line as in the prior art, so there is no need for post-finishing, and the spring is eroded like a chemical production plant, water, air, etc. with high reliability. It is possible to provide a flexible hose manufacturing method and a hose that are useful when sending such a product.
[Brief description of the drawings]
FIG. 1 is an explanatory view of a method for producing a flexible hose according to the present invention.
FIG. 2 is an explanatory view of a flexible hose obtained by Example 1 according to the present invention.
FIG. 3 is an explanatory view showing a relationship between a hose and a spring in the method for manufacturing a flexible hose according to the present invention.
FIG. 4 is an explanatory view of a spring used in manufacturing a flexible hose according to the present invention.
FIG. 5 is an explanatory view of a half type for explaining the prior art 1;
FIG. 6 is an explanatory view of a half type for explaining the related art 2;
[Explanation of symbols]
1 ... Hose,
2 ... Spring (cover),
3 ... outer cylinder,
4, 5 ... sealing material,
6 ... pipe,
7 ... Band heater,
8: Flexible pipe,
9: Insulating material.

Claims (2)

A step of winding a spiral covering around at least a part of the outer periphery of the thermoplastic resin hose, a step of inserting the hose into an outer cylinder in this state, and a state where both ends of the hose are sealed A step of softening by heating, a step of applying an internal pressure from the inside of the hose, a step of cooling the hose and processing the surface of the hose into a spiral shape, and removing the spiral covering on the outer periphery of the outer tube and the hose And a process for producing a flexible hose having a helical surface . A flexible hose having a helical surface produced by the production method according to claim 1 .

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