JP2003305768A - Method for manufacturing curved resin tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for certainly manufacturing a bent resin tube having a complicated shape of every kind at a low cost without manufacturing a plurality of molds. <P>SOLUTION: A flexible internal insertion member 3 having a somewhat smaller inside diameter than the inside diameter of a resin tube 1 and also having a first heating means is set at a position of a bending processing means 4 in such a state that the member 3 is inserted in the resin tube 1. Then after the part to be bent of the resin tube 1 is preheated, it is moved to the position of the bending means 4 (the insertion member 3) and heated from the internal face side by the first heating means and at the same time or thereafter, the resin tube 1 is bent by the bending means 4 of which the contact face with the resin tube 1 is heated by a second heating means. Finally, the bent part of the resin tube 1 is cooled by a cooling means installed on at least either one of the insertion member 3 or the bending means 4. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a bent resin tube, and more particularly to a method for manufacturing a bent resin tube made of a thermoplastic resin material and having at least a bent portion.

[0002]

2. Description of the Related Art In recent years, a thermoplastic resin has come to be used as a material for forming a vacuum tube, a low pressure air tube and the like for automobiles for the purpose of weight reduction and cost reduction of automobiles. And, in such a resin tube, due to the concentration of various devices in the engine room,
A three-dimensionally complicated bent shape is required.

Therefore, for example, in Japanese Unexamined Patent Publication No. 8-216246, as shown in FIG. 3, a metal pipe mold 102 is preliminarily bent into a desired bent shape and provided with openings along the longitudinal direction. There is disclosed a method of manufacturing a bent resin tube by fitting a preheated resin tube precursor 101, heating this together with a mold 102 to form a target shape, and then cooling and removing from the mold 102. . However, in this method, the pre-heated resin tube precursor 101 is attached to the mold 102 having a complicated shape, the mold 102 is loaded into a heating furnace for heating, and the work is taken out after heating. There is a problem that productivity is inferior because there are many operations that require manpower, such as the work of removing from. If the preheating temperature is increased to increase the productivity, the resin precursor 101 is excessively softened, and there is a high possibility that a kink will occur when the resin precursor 101 is fitted into the mold 102. In particular, the more complicated 3
Although a three-dimensional bent shape is required, it is more difficult to prevent kinks when the bending angle is large, and thus there are cases in which the method cannot be practically processed. Further, when manufacturing resin tubes having different bent shapes, it is necessary to manufacture a new mold having a complicated shape each time, which is very troublesome (prior art 1).

Further, in Japanese Patent Laid-Open No. 11-58510, as shown in FIG. 4, while heating from the outer peripheral side of the resin tube 201 with air heaters 204A and 204B,
When the bending member 202 having the heating means 204C is inserted into the resin tube 201 and heated from the inside and outside of the resin tube 201, at the same time or after that, the straight tubular bending member 202 is rotated around the portion to be bent as the rotation center. Therefore, a method of bending is disclosed. According to this method, when a resin tube having bent portions with different bending angles is manufactured only at one place, the manufacturing cost can be reduced because it can be manufactured without manufacturing a plurality of molds. It cannot be applied to the production of a resin tube having a complicated shape having a plurality of parts. Further, since the straight tubular bending member 202 is rotated around the portion to be bent as a rotation center, there is a high possibility that the bending portion will be kinked when the bending angle is large (prior art 2).

[0005]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method capable of reliably manufacturing bent resin tubes of various complicated shapes at low cost without manufacturing a plurality of molds.

[0006]

The invention according to claim 1 is a method for producing a bent resin tube made of a thermoplastic resin material and having a bent portion at least in a part thereof, wherein the bent portion of the resin tube is provided. A supporting step for supporting the resin tube by inserting an insertion member having an inner diameter slightly smaller than the inner diameter of the resin tube and having a first heating means, and performing a bending process for the resin tube. The first part
The inner surface side heating step of heating from the inner surface side by the heating means and the inner surface side heating step, simultaneously with or after the inner surface side heating step, bends the resin tube by the bending processing means in which the surface in contact with the resin tube is heated by the second heating means. Bending process to process,
A method for manufacturing a bent resin tube, comprising a cooling step of cooling a bent portion of the resin tube by a cooling means provided in at least one of the insertion member and the bending means. .

According to a second aspect of the invention, before the supporting step,
The method for producing a bent resin tube according to claim 1, further comprising a preheating step of preheating a portion of the resin tube to be bent.

According to a third aspect of the invention, the bending means is
The method for manufacturing a bent resin tube according to claim 1 or 2, comprising a pair of benders and a bender holder.

A fourth aspect of the present invention is the method for manufacturing a bent resin tube according to any one of the first to third aspects, wherein the insertion member is formed of a flexible metal tube.

According to a fifth aspect of the present invention, the first heating means is a high temperature gas of either steam or heated air, and the insertion member is provided with a blowing hole for the high temperature gas. It is a manufacturing method of a bending resin tube given in any 1 paragraph of Claims 1-4.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 schematically shows an apparatus for manufacturing a bent resin tube according to an embodiment of the present invention. Reference numeral 1 is a thermoplastic resin tube precursor (hereinafter, simply referred to as “resin tube”) that is subjected to bending processing, and the resin tube 1 is held substantially horizontally by a chuck (not shown), and this resin tube is sequentially held by the chuck. 1 Transferred in the longitudinal direction. Reference numeral 2 indicates a preheating furnace for preheating the resin tube 1, for example, including a heating wire heater,
The preheating furnace 2 is provided with an opening penetrating the central portion,
The resin tube 1 is configured to be preheated by sequentially passing through the opening.

Reference numeral 3 is an insertion member that is inserted into the resin tube 1 and has a cylindrical shape with an inner diameter slightly smaller than the inner diameter of the resin tube 1, and is supported on the rear end side of the insertion member 3 as a support member. The tube 3A is connected. The insertion member 3 may be made of a flexible tube made of metal such as stainless steel or a rubber tube so as to have flexibility. For example, the following heating means (first heating means) is used for the insertion member 3.
And a cooling means is provided. That is, a plurality of gas blowing holes 3B are provided in the side surface of the insertion member 3 in the circumferential direction, a switching valve 3C is provided at the rear end of the support tube 3A, and a high temperature gas such as steam or heated air is used as a heating medium. As a cooling medium, a cooling gas such as room temperature air can be selectively introduced, and a high temperature gas or a cooling gas is blown out from the gas blowing hole 3B through the support pipe 3A. As a result, the portion of the resin tube 1 to be bent can be heated or cooled from the inner surface side. Further, a sealing mechanism 3D such as an O-ring is provided at the tip of the insertion member 3 so that high temperature gas or cooling gas can flow from the gap between the tip of the insertion member 3 and the inner surface of the resin tube 1 to the front side of the resin tube 1. It is preferable that the portion to be bent can be quickly heated or cooled so as not to leak out.

Reference numerals 4A and 4B are a pair of benders and bender holders that constitute the bending means 4, and are provided on the front end side of the resin tube 1 with respect to the preheating furnace 2. Each of the vendor 4A and the vendor presser 4B has a heating means (second
Of the gas flow path 41
A and 41B are provided, and switching valves 42A and 42B are provided on the gas supply side of the flow paths 41A and 41B, respectively, so that the high temperature gas and the cooling gas can selectively flow.

Next, a method of manufacturing a bent resin tube having bent portions at a plurality of locations by using the manufacturing apparatus having the above structure will be described.

First, the preheating furnace 2 is heated to a predetermined temperature. Next, the insertion member 3 is inserted into the straight tubular resin tube 1, and the insertion member 3 is set in accordance with the position of the bending means 4. Then, the resin tube 1 is set so that the first bent portion comes into the preheating furnace 2.
Hold it for a predetermined time as it is and bend the bent part for example about 12
Preheat to about 0 ° C. By this preheating, the bent portion of the resin tube 1 is softened to some extent (preheating step).

Next, with the position of the insertion member 3 fixed,
Only the resin tube 1 is advanced by a predetermined distance by the chuck, and the preheated bending portion is aligned with the position of the bending means 4 (4A, 4B) (that is, the position of the insertion member 3) (supporting step). .

Next, the switching valve is operated to blow out a high-temperature gas of a predetermined temperature from the gas blowing hole 3B of the insertion member 3 via the support tube 3A, and the bent portion of the resin tube 1 is pressed from the inner surface side. , Above the preheating temperature, eg about 1
Heat to about 60 ° C. As a result, the bent portion of the resin tube 1 is further softened, and subsequent bending is facilitated (inner surface heating step).

On the other hand, during this period, the bending valves 4A and 42B, which are the bending means 4, are operated by switching valves 42A and 42B, respectively, so that the respective gas flow paths 4 are formed.
A high temperature gas is circulated through 1A and 41B to sufficiently heat the surface of the resin tube 1 in contact with the outer surface of the bent portion. Then, at the same time as or after the inner surface side heating step, the bent portion of the resin tube 1 is bent to a predetermined bending angle by the bender 4A and the bender holder 4B.
During the bending process, the flexible insertion member 3 exists on the inner surface side of the bending portion of the resin tube 1, and the insertion member 3 bends as the resin tube 1 bends (see FIG. 2). ), Even if the bending angle is large, the resin tube 1
Does not kink. In addition, it is preferable to perform the bending process at the same time as the inner surface heating process. That is, even during the bending process, by continuously blowing the high temperature gas from the gas blowing holes 3B of the insertion member 3 to the inner surface of the resin tube, the bending part of the resin tube 1 is not cooled and hardened during the bending process. This is because kinks are less likely to occur. Similarly, for the same reason, it is desirable to keep the high-temperature gas flowing through the bending means 4 during bending (bending step).

After the resin tube 1 is bent to a predetermined bending angle, the switching valves 3E, 42A and 42B switch the high temperature gas to each part to the cooling gas. As a result, the bent portion of the resin tube 1 is cooled from the inner surface by blowing the cooling gas from the gas blowing hole 3B of the insertion member 3 onto the inner surface of the bent portion of the resin tube 1, and the bender 4A and the bender holder are pressed. Since it is also cooled from the outer surface in contact with 4B, it is rapidly cooled and solidified, and the formation of the first bent portion is completed (cooling step).

While the first inner surface heating step to bending step are being carried out, the second bending step is preheated in the preheating furnace 2 (second preheating step).

After the bent portion of the resin tube 1 is sufficiently cooled and solidified, the bending means 4 (4A, 4B) is retracted from the resin tube 1, and the resin tube 1 is fixed while the position of the insertion member 3 is fixed. The chuck is moved forward, and the next bending portion preheated in the preheating furnace 2 is set at the position of the bending means 4 (that is, the position of the insertion member 3). At this time, if the bending direction of the next bent portion is different from the bending direction of the first bent portion, the resin tube 1 should be set by rotating it about its axis by an angle matching the bending direction of the next bent portion. good. Alternatively, instead of rotating the resin tube 1, the bending means 4 may be configured to be rotatable around the axis of the resin tube 1 and aligned with the bending direction of the next bent portion. During the movement of the resin tube 1, the insertion member 3 is returned to the straight tube shape at the straight tube portion of the resin tube 1 due to its flexibility (second supporting step). In the previous (first) cooling step, if the resin tube 1 is moved before the cooling and solidification of the bent portion is insufficient, the portion bent to the predetermined bending angle may be deformed or damaged. Sufficient cooling is important. After the second supporting step, a new bent portion is formed by repeating the inner surface heating step, the bending step, and the cooling step as in the first series of steps.

Thereafter, by repeating a series of steps from the preheating step to the cooling step in the same manner as described above, even a complicated three-dimensional bent shape having bent portions at a plurality of points can be easily and surely obtained. Bending resin tube can be molded.

According to this method, the next bending portion can be preheated during the inner surface heating step, the bending step, and the cooling step, so that the productivity is remarkably improved.

Even if the intervals between the plurality of bent portions of the resin tube are not constant, the next preheating step can be performed in parallel during the inner surface heating step, the bending step, and the cooling step. For example, it is preferable that the horizontal position of the preheating furnace can be freely changed.

In the above embodiment, an example (invention of claim 2) having a preheating step has been described.
A method in which these steps are omitted also belongs to the technical scope of the present invention (the invention of claim 1). That is, without performing preheating, the inner surface of the bent portion of the resin tube 1 may be immediately blown with high-temperature gas from the gas blowout hole 3B of the insertion member 3 to sufficiently bend the bent portion of the resin tube 1. This is because it can be softened. However, it is necessary to heat for a longer time than in the case where preheating is performed, and productivity is inferior to that in the above embodiment.

Further, in the above-mentioned embodiment, the cooling means is provided on both the interpolating member 3 and the bending means 4, but it is within the technical scope of the present invention to provide cooling means on only one of them. . For example, a cooling means is provided only in the insertion member 3,
If the bending means 4 is not provided with a cooling means, immediately after the bending work is completed, the bending means 4 such as the bender 4A and the bender holder 4B may be retracted from the resin tube and cooled by the cooling means of the insertion member 3. Although the cooling time becomes longer than the case where both are provided, the bent portion of the resin tube 1 can be sufficiently cooled and solidified in a relatively short time.

In the present embodiment, the resin tube 1
Is held substantially horizontally by the chuck, but the invention is not limited to this, and it may be held vertically or obliquely.

In this embodiment, the heating wire heater is used as the heat source for preheating, but a ceramic heater, a far infrared heater, a high temperature gas such as steam or heated air, or a halogen lamp may be used.

In this embodiment, high temperature gas such as steam or heated air is used as the heating means (first and second heating means), but a heating wire heater may be incorporated.

Further, in the present embodiment, a cooling gas such as room temperature air is used as the cooling means, but water cooling or oil cooling may be used.

[0032]

As described above, according to the present invention, it is not necessary to manufacture a plurality of molds, and the work requiring labor is largely omitted. Bending resin tube can be manufactured.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an outline of an apparatus for manufacturing a bent resin tube according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a manner in which a resin tube is bent by the bent resin tube manufacturing apparatus according to the embodiment of the present invention.

FIG. 3 is a perspective view showing a method for manufacturing a bent resin tube according to the related art 1.

FIG. 4 is a perspective view showing a method for manufacturing a bent resin tube according to the related art 2.

[Explanation of symbols]

1 ... Resin tube precursor (resin tube) 2 ... Preheating furnace 3 ... Interpolation member 3A ... Support tube 3B ... Gas blowout hole 3C ... Switching valve 3D ... Seal mechanism 4 ... Bending means 4A ... Vendor 41A ... Gas flow path 42A ... Switching valve 4B ... Hold down vendor 41B ... Gas flow path 42B ... Switching valve

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 3H111 AA01 BA15 CA57 CB02 CB14                       DA26 EA12 EA18                 4F209 AG08 AH17 NA01 NB01 NG03                       NH06 NH09 NJ13 NJ14 NJ21                       NK01 NK07

Claims (5)

[Claims] 1. A method of manufacturing a bent resin tube made of a thermoplastic resin material, at least a part of which has a bent portion, wherein the bent portion of the resin tube can have an inner diameter slightly smaller than the inner diameter of the resin tube. A supporting step of supporting a resin tube by inserting an insertion member having flexibility and having a first heating means, and a portion to be bent of the resin tube are formed on the inner surface side by the first heating means. And an inner surface side heating step of heating from the inner surface side heating step, and a bending step of bending the resin tube by a bending means whose surface contacting the resin tube is heated by the second heating means at the same time as or after the inner surface side heating step. A cooling step of cooling the bent portion of the resin tube by a cooling means provided in at least one of the insertion member and the bending means. Bending resin tube manufacturing method. 2. The method for producing a bent resin tube according to claim 1, further comprising a preheating step of preheating a portion of the resin tube to be bent before the supporting step. 3. The method for manufacturing a bent resin tube according to claim 1, wherein the bending means comprises a pair of benders and a bender holder. 4. The method for manufacturing a bent resin tube according to claim 1, wherein the insertion member is formed of a metal flexible tube. 5. The first heating means is a high temperature gas of either steam or heated air, and the insertion member is provided with a blowing hole for the high temperature gas.
5. The method for manufacturing a bent resin tube according to any one of 4 to 4.