JP2002086560A - Synthetic resin biaxially drawn pipe having diameter- expanded section, and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a synthetic resin biaxially drawn pipe having a diameter-expanded section, which is excellent in strength of not only the pipe main body but also the diameter- expanded section, and its manufacturing method. SOLUTION: A diameter-expanding die for forming the diameter-expanded section deforms into an external surface shape going along the internal surface shape of the diameter-expanded section to be obtained from an external surface shape going along the approximate internal surface shape of a synthetic resin biaxially drawn original pipe. Under a state wherein such a diameter-expanding die is inserted in a diameter-expanded section forming section of the synthetic resin biaxially drawn original pipe, the diameter-expanded section forming section is heated to an orientation enable temperature of the synthetic resin. Then, while the heated state is maintained, the expanding/contracting die is expanded deformed to the external surface shape going along the internal surface shape of the diameter-expanded section to be obtained in a diameter-expanded section forming process. This manufacturing method is constituted by providing such a diameter-expanded section forming process. Also, by inserting the diameter-expanding die in the diameter-expanded section forming section under a state wherein the outer peripheral surface of the diameter-expanding die is coated with an elastic material, the internal surface of the diameter-expanded section forming section is prevented from being damaged, and cracks are prevented from being generated on the internal surface of the diameter-expanded section forming section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic resin biaxially stretched tube having an enlarged diameter portion and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing a synthetic resin pipe having an enlarged diameter portion, which is integrally provided with an enlarged diameter portion such as a receiving portion which is an enlarged diameter portion at an end of the tube main body portion, a synthetic resin tube is used. An enlarged-diameter portion forming die having an outer shape that is substantially the same as the inner surface shape of the enlarged portion that is to be obtained in a state where the enlarged-diameter portion forming portion of the original tube is preliminarily heated to an orientation-possible temperature, which is a processing temperature, is used. It is common to manufacture by press fitting into the forming part.

In Japanese Patent No. 3018147, first,
The enlarged diameter forming portion such as the receiving port forming portion of the synthetic resin raw tube is 140
A large diameter portion which is immersed in glycerin oil at a temperature of 180 ° C. to 180 ° C. to be softened to a state in which it can be plastically deformed, and which expands to an outer shape substantially the same as the inner shape of the large diameter portion to be obtained when the softened large diameter portion is expanded. There has been proposed a method of inserting a forming die (expansion member) and then expanding the expanding portion forming expansion member to obtain a synthetic resin tube with a expanded portion.

[0004] As a method of processing a receiving port or the like at the end of the pipe main body, there is a method described in Japanese Patent Application Publication No. 11-512358. The method comprises pressing the end of the tube over the area of the end portion of the first cylindrical mandrel element;
While heating to a temperature higher than the glass transition point of the amorphous resin or the melting point of the crystalline resin, and maintaining the remaining portion other than the end of the tube at a temperature lower than that, the resin in the heating region is heated to the glass transition point or When at a temperature higher than the melting point, the bottom portion of the receptacle was pressed into a second mandrel element axially aligned with the first mandrel element to form the bottom portion of the receptacle and then cooled. Later, the end of the tube is withdrawn from the mandrel element.

[0005] However, when a biaxially stretched synthetic resin tube which is excellent in strength such as earthquake resistance and can be made thinner is used as a raw tube, the above-described manufacturing method has the following problems. There is.

That is, when the stretched resin is heated, it tends to return to the state before stretching. Therefore, it becomes difficult to insert the expansion and contraction mold, and since the expansion and contraction mold is pressed into the original tube, a compressive force is applied in the axial direction of the original tube when expanding the diameter, the orientation balance of the resin is lost, and the strength in the axial direction is reduced. May drop.

In the method described in Japanese Patent Application Laid-Open No. 11-512358, the pipe end is pushed into the mandrel element at the time of forming the receiving port, so that a compressive force is applied to the pipe at the time of expanding the diameter. In particular, a large compressive force is applied to the groove portion having the largest diameter, which tends to cause a loss of the balance of the orientation of the resin, and may decrease the strength in the axial direction.

Further, when an expanding / contracting die having a structure in which the movable portion slides and expands and contracts in diameter is used as the expanding / contracting die, there is a portion where the movable portion has an edge in a contracted state, and heating is performed in that state. Inserting a damaged original tube, or heating after inserting the original tube, scratches the inner surface of the enlarged diameter part (receptacle),
Cracks may occur and the strength in the axial direction may decrease.

[0009]

SUMMARY OF THE INVENTION In view of such circumstances, the present invention provides a biaxially stretched synthetic resin tube having a large diameter portion, which is excellent in the strength of the large diameter portion as well as the tube body. It is intended to provide a way.

[0010]

In order to achieve such an object, a synthetic resin biaxially stretched tube with an enlarged diameter portion according to the invention of claim 1 of the present invention (hereinafter referred to as “Claim 1 Axle-stretched tube) is a synthetic resin biaxially stretched tube having a diameter-expanded portion having a diameter-expanded portion formed by partially expanding the diameter of a synthetic-resin biaxially stretched original tube. In order to satisfy the relationship of the stretching ratio in the axial direction of the original stretch tube ≦ the axial stretching ratio of the enlarged diameter portion, the stretching ratio in the circumferential direction of the synthetic resin biaxially stretched original tube ≦ the stretching ratio in the circumferential direction of the enlarged diameter portion. did.

[0011] The biaxially stretched synthetic resin tube with an enlarged diameter portion (hereinafter referred to as "biaxially stretched tube of claim 2") according to the second aspect of the present invention is the biaxially stretched tube of the first aspect. In the tube,
The enlarged diameter portion is deformed into an outer shape along the inner surface shape of the enlarged diameter portion to be obtained from the outer shape along the substantially inner surface shape of the synthetic resin biaxially stretched raw tube. In the state of being inserted into the enlarged-diameter portion forming portion of the original drawing tube, the enlarged-diameter portion forming portion is heated to a temperature at which the synthetic resin can be oriented, and while maintaining this heating state, the enlarged-diameter portion forming die is enlarged. The enlarged diameter portion is formed by deforming the outer surface shape along the inner surface shape of the portion.

According to the third aspect of the present invention, there is provided a biaxially stretched synthetic resin tube having an enlarged diameter portion (hereinafter referred to as a “biaxially stretched tube of the third aspect”). In the tube,
Amorphous resin was used as the synthetic resin, and the material was heated to a temperature at which alignment can be performed at a temperature equal to or higher than the glass transition temperature (glass transition temperature + 40 ° C.).

[0013] The biaxially stretched synthetic resin tube with a large diameter portion (hereinafter referred to as "biaxially stretched tube of claim 4") according to the invention of claim 4 of the present invention is the biaxially stretched tube of claim 2 of the present invention. In the tube,
A crystalline resin was used as the synthetic resin, and the material was heated at an orientation-possible temperature equal to or higher than the melting point (melting point + 40 ° C.).

The method for manufacturing a biaxially stretched synthetic resin tube having an enlarged diameter portion according to the invention of claim 5 of the present invention (hereinafter referred to as “the manufacturing method of claim 5”) is a method for manufacturing a biaxially stretched synthetic resin. A large-diameter expansion part forming part of a synthetic resin biaxially stretched original pipe is used for forming a large-diameter expansion part that is deformed into an external shape that conforms to the internal surface shape of the large-diameter part that is to be obtained from the external surface shape that follows the substantially internal surface shape of the pipe. After the enlarged diameter forming section is heated to the temperature at which the synthetic resin can be oriented in the state of being inserted into the hole, the outer shape conforms to the inner surface shape of the enlarged diameter section in order to obtain the expansion mold while maintaining this heated state. A configuration is provided that includes a step of forming an enlarged diameter portion.

The method for producing a synthetic resin biaxially stretched tube with an enlarged diameter portion according to the invention of claim 6 of the present invention (hereinafter referred to as “the production method of claim 6”) is the production method of claim 5. In, before inserting the expansion mold into the synthetic resin biaxially stretched raw tube, insert an auxiliary mold having an outer diameter that is substantially the same as the inner diameter of the synthetic resin biaxially stretched raw tube into the enlarged diameter portion forming portion, and the temperature is lower than the orientation-possible temperature After the preheating step of heating the enlarged-diameter portion forming section to the preheating temperature, the auxiliary mold in the enlarged-diameter portion forming section in the preheated state is replaced with an enlarging / reducing mold, and the enlarged-diameter portion forming step is performed.

A method for producing a biaxially stretched synthetic resin tube having an enlarged diameter portion according to the invention of claim 7 of the present invention (hereinafter referred to as “the production method of claim 7”) is claim 5 or claim 5. 6
In the manufacturing method of (1), both ends of the synthetic resin biaxially stretched original tube are restricted by regulating members at least at the time of the step of forming the enlarged diameter portion, so that the axial contraction of the synthetic resin biaxially stretched original tube is suppressed.

[0017] The method for producing a biaxially stretched synthetic resin tube with an enlarged diameter portion according to the invention of claim 8 of the present invention (hereinafter referred to as "the production method of claim 8") is described in claims 5 to 5. In any one of the manufacturing methods of No. 7, an amorphous resin is used as the synthetic resin, and the glass is heated to a temperature at which alignment can be performed at a glass transition temperature or higher (glass transition temperature + 40 ° C.) or lower.

The method for manufacturing a biaxially stretched synthetic resin tube with an enlarged diameter portion according to the invention according to claim 9 of the present invention (hereinafter referred to as "the manufacturing method of claim 9") is as defined in claims 5 to 5. In any one of the manufacturing methods of No. 7, a crystalline resin is used as the synthetic resin, and heating is performed at an alignable temperature equal to or higher than the melting point (melting point + 40 ° C.) or lower.

In the present invention, although not particularly limited, examples of the amorphous resin include polyvinyl chloride, and examples of the crystalline resin include polyethylene and polypropylene.

In the method for producing a biaxially stretched synthetic resin tube having an enlarged diameter portion according to the present invention, an outer peripheral surface (including a movable portion) of an expansion / contraction die is provided.
If the enlarged diameter mold is inserted into the enlarged diameter portion forming part of the synthetic resin biaxially stretched original tube while the enlarged diameter portion is molded with the elastic material, the inner diameter of the enlarged diameter portion is damaged. Sticking and cracking can be prevented.

Examples of the elastic material used in the production method of the present invention include, for example, natural rubber, synthetic rubber, and thermoplastic elastomer. Among them, it is preferable to use a synthetic rubber having excellent heat resistance.

Specific examples of the synthetic rubber include SBR (styrene-butadiene rubber), NBR (nitrile-butadiene rubber), CR (chloroprene rubber), EPDM (ethylene-propylene rubber), and fluorine-based rubber. .

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below.
This will be described in detail with reference to the drawings.

FIGS. 1 to 3 show a method of manufacturing a synthetic resin biaxially stretched tube with a receiving port, which is one embodiment of the method of manufacturing a synthetic resin biaxially stretched tube with an enlarged diameter portion, according to the present invention in the order of steps. I have.

In this manufacturing method, as shown in FIG. 1 (a), first, a synthetic resin biaxially stretched raw tube (hereinafter, simply referred to as "raw tube") 1 is made of a metal having an outer diameter that is substantially the same as the inner diameter. And an auxiliary die 2 having a length slightly longer than the axial length of a receiving portion forming portion (hereinafter, referred to as a “receiving portion forming portion”) 11 which is an enlarged diameter portion of the original tube 1. Into the receiving port forming part 11 of the original tube 1.

Next, the receptacle forming section 11 is preheated by a heater (not shown) to a preheating temperature lower than a temperature at which the synthetic resin constituting the raw tube 1 can be oriented.

After the completion of the preliminary heating, as shown in FIG. 1 (b), the auxiliary mold 2 in the receptacle forming portion 11 is protruded toward the other end of the original tube 1 by the tip of the expansion / contraction die 3, and the auxiliary mold 2 and the expansion / contraction metal In addition to replacing the mold 3, regulating members 4 a,
4b is attached.

The expansion / contraction mold 3 includes a shrinkage preventing portion 31 and
It is divided into first to fourth four enlargement / reduction portions 32 to 35.

The shrinkage preventing portion 31 has a cylindrical shape having an outer diameter substantially equal to the inner diameter of the synthetic resin biaxially stretched raw tube 1.

As shown in FIG. 1 (b), the maximum diameter portion of the first expanding / contracting portion 32 becomes substantially the same as the inner diameter of the original tube 1 when contracted.
As shown in FIG. 2 (a), the outer surface is shaped like a truncated cone along the inner surface of the tapered portion of the receptacle to be obtained at the time of enlargement.

As shown in FIG. 1 (b), the second expanding / contracting portion 33 has a cylindrical shape having substantially the same diameter as the inner diameter of the original tube 1 when contracted, and as shown in FIG. It is designed to have a cylindrical shape having substantially the same diameter as the inner diameter of the parallel portion on the back side of the receiving port.

As shown in FIG. 1B, the third expanding / contracting portion 34 has a maximum diameter portion substantially equal to the inner diameter of the original tube 1 when contracted,
As shown in FIG. 2A, the outer shape is the same as the inner shape of the rubber ring mounting groove of the receptacle to be obtained at the time of enlargement.

As shown in FIG. 1 (b), the fourth expanding / contracting portion 35 has a cylindrical shape having substantially the same diameter as the inner diameter of the original tube 1 when contracted, and as shown in FIG. It is designed to have a cylindrical shape having substantially the same diameter as the inside diameter of the parallel portion on the entrance side of the receiving port to be made.

The expansion / contraction mechanism of each of the expansion / contraction sections 32-35 is as follows.
Although not particularly limited, a mechanism disclosed in Japanese Patent No. 3018147 or Japanese Patent Application Laid-Open No. 57-83423,
For example, as shown in FIG.
, Four small expansion members 37, a slide shaft 38, and a spindle-shaped slide member 39 slidable along the slide shaft 38.

Then, each of the enlargement / reduction portions 32 (33 to 35)
When the slide member 39 slides to the large diameter side along the slide shaft 38, as shown in FIG.
7 slides into the inside of the large expansion / contraction member 36, and the four large expansion / contraction members 36 are reduced in diameter so that their edges are substantially in contact with each other, and as shown in FIG.
Slides along the slide shaft 38 toward the small diameter side to push the small expansion / contraction member 37 and the large expansion / contraction member 36 outward, and finally enters between the large expansion / contraction member 36 and the large expansion / contraction member 36 to expand. It is in a diameter state.

As shown in FIGS. 1 (b) and 2 (a), the regulating members 4a and 4b are provided on a base (not shown) so as to be slidable and fixable at predetermined positions. A ring portion 41 having an inner diameter larger than the outer diameter of the receiving port 51, and a chuck 4 provided radially on the ring portion 41 and having a tip movable in the central axis direction of the ring portion 41.
2, so that the end of the original tube 1 can be clamped between the chuck 42 and the fourth expansion / contraction section 35 of the auxiliary mold 2 or the expansion / contraction die 3. Also, the chuck 42 of the regulating member 4a
Although not shown, there is provided a mechanism for retracting while holding the tube end sandwiched between the mold 3 and the mold 3 in conjunction with the enlargement of the mold 3.

Next, the receptacle forming section 11 is heated by the heater.
Is heated above the temperature at which it can be oriented, and while maintaining this heating state, as shown in FIG.
The fourth expanding / contracting portions 32 to 35 are enlarged to plastically deform while maintaining the orientation of the receiving port forming section 11 of the original tube 1 in the shape of the receiving port 51.

After the plastic deformation is completed and the resin is cooled and solidified, the first contracted portion 32 to the fourth contracted portion 35 of the expansion / contraction mold 3 are returned to the contracted state as shown in FIG.

Finally, the chuck 4 of the regulating members 4a, 4b
After the release of the chuck by the chuck 2, the expansion mold 3 and the auxiliary mold 2 are pulled out to provide a receptacle 51 having a rubber ring mounting groove 52 at one end as shown in FIG. Thus, a synthetic resin biaxially stretched tube 5 having the tube main body 53 is obtained.

As described above, this manufacturing method includes the steps of forming the expansion / contraction die 3 which has been contracted to an outer diameter substantially equal to the inner diameter of the receptacle forming section 11 before the receptacle forming section 11 is heated to a temperature at which orientation can be performed. After the heating is completed,
Since the enlargement / reduction mold 3 is enlarged, even if the receiving port forming part 11 tries to shrink due to heating, it is received by the enlargement / reduction mold 3 and contraction is suppressed. Accordingly, the stretching ratio in the axial direction of the tube body 53 (the stretching ratio in the axial direction of the raw tube 1) ≦ the stretching ratio in the axial direction of the receiving portion 51, the tube body 53
Thus, a synthetic resin biaxially stretched pipe 5 with a receptacle that satisfies the relationship of (1) the circumferential stretching ratio (the circumferential stretching ratio of the raw tube 1) ≦ the circumferential stretching ratio of the receiving port 51 can be obtained.

The auxiliary mold 2 is preliminarily heated in a state of being inserted into the receptacle forming portion 11 before the diameter expansion by the enlarging / reducing mold 3, and after the preliminary heating is completed, the auxiliary mold 2 and the auxiliary mold 2 of the receptacle forming portion 11 are enlarged. Since the enlarged diameter portion forming step is performed by replacing the mold 3, the productivity can be improved at low cost.

That is, it takes a considerable amount of time to heat the raw tube 1 from room temperature to a temperature at which alignment can be performed.
When the heating is performed in a state where the expansion mold 3 is inserted into the original tube 1 from the beginning without using the method, a large number of expansion molds 3 having a complicated structure and a high manufacturing cost are required to improve the productivity. Must be prepared.

Then, as described above, the auxiliary mold 2 having a simple structure is preheated to a temperature close to the orientable temperature in advance, and the expansion mold 3 is inserted into the preheated original tube 1. By heating to the temperature at which alignment can be performed, the time required to heat the receptacle forming portion 11 to the temperature at which alignment can be performed after insertion of the expansion / contraction die 3 can be reduced. Therefore, it is possible to secure the same productivity as in the case of using a large number of expansion / contraction dies 3 without using the auxiliary dies 2 only by preparing one expansion / contraction die 3 for a plurality of auxiliary dies 2, Productivity can be improved at low cost.

Further, since both ends of the original tube 1 are regulated by the regulating members 4a and 4b at the time of heating to a temperature at which alignment can be performed and at the time of expanding the diameter, the contraction of the original tube 1 in the axial direction is more reliably prevented. it can.

The synthetic resin biaxially-rolled pipe 5 with a receiving port obtained by the above-described molding method has a draw ratio in the axial direction of the pipe body 53 (a draw ratio in the axial direction of the original pipe 1) ≦ the receiving port 51 as described above. Since the axial draw ratio of the tube portion, the circumferential draw ratio of the tube body 53 (the circumferential draw ratio of the raw tube 1) ≦ the circumferential draw ratio of the receiving portion 51, the receiving portion 51 is satisfied. Is also excellent in strength.

The biaxially stretched synthetic resin tube having the enlarged diameter portion according to the present invention and the method for producing the same are not limited to the above-described embodiment.

For example, in the above-described embodiment, the receiving port is formed at one end, but the receiving port may be provided at both ends. Further, it can be used also in a case where an enlarged diameter portion is provided at an intermediate portion of the original pipe.

In the above embodiment, the regulating member 4
a and the expansion / contraction mold 3, and between the regulating member 4 b and the auxiliary mold 2, the tube end of the original tube 1 is sandwiched to restrict the movement in the axial direction. A regulating member may be provided so that the tube end is sandwiched between the inner and outer regulating members.

Next, another embodiment of the method for producing a biaxially stretched synthetic resin tube having a large-diameter portion according to the present invention will be described.

The enlargement / reduction mold 30 used in this embodiment has the same configuration as the enlargement / reduction mold 3 shown in FIGS.

That is, as shown in FIGS. 5 and 6,
6 includes a contraction preventing section 31, a first scaling section 32, a second scaling section 33, a third scaling section 34, and a fourth scaling section 35.
As shown in FIG.
8, the small expansion / contraction member 37 slides into the inside of the large expansion / contraction member 36, and the four large expansion / contraction members 36 reduce their diameters so that their edges substantially contact each other. As shown in (b), the slide member 39 slides to the small diameter side along the slide shaft 38 and pushes the small expansion / contraction member 37 and the large expansion / contraction member 36 outward, and finally, the large expansion / contraction member 36 It is configured so as to enter between the large expansion / contraction member 36 to be in a state of increased diameter.

In this embodiment, the enlargement / reduction mold 30 is used.
Of the outer peripheral surface (including the movable portion) of an elastic material (for example, SBR, N
BR, etc., 6
Inserted into the receptacle forming part 11 of the receptacle 51 (enlarged diameter part)
Is characterized by being molded. The expansion / contraction mold 30
The process other than covering the outer peripheral surface of the first embodiment with the elastic material 6 is the same as that of each of the above embodiments.

According to this embodiment, since the outer peripheral surface of the expansion / contraction die 30 is covered with the elastic material 6, even if the edge of the movable portion stands when the expansion / contraction die 30 is in the reduced diameter state, The elastic member 6 protects the inner surface of the receiving portion forming portion, so that the inner surface of the receiving portion forming portion is not damaged or cracked.
The strength in the axial direction can be ensured.

[0054]

As described above, the biaxially stretched synthetic resin pipe with a large diameter portion according to the present invention is constructed as described above, so that the diameter of the large diameter portion also exhibits a sufficient strength. In this case, the strength of the connection portion can be sufficiently ensured.

The method for producing a biaxially stretched synthetic resin tube with a large-diameter portion according to the present invention is configured as described above.
The synthetic resin biaxially stretched tube of the present invention can be reliably manufactured.

According to the sixth aspect, productivity can be improved at low cost.

Further, according to the seventh aspect, the contraction in the axial direction can be more reliably prevented. That is, the synthetic resin biaxially stretched tube with the enlarged diameter portion of the present invention can be manufactured more reliably.

In the method for manufacturing a biaxially stretched synthetic resin tube having a diameter-expanding portion according to the present invention, the outer peripheral surface (including the movable portion) of the expansion / contraction die
If the enlarged diameter mold is inserted into the enlarged diameter portion forming part of the synthetic resin biaxially stretched original tube while the enlarged diameter portion is molded with the elastic material, the inner diameter of the enlarged diameter portion is damaged. Since attachment or cracking can be prevented, the strength in the axial direction does not decrease, and performance can be ensured for a long period of time.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one embodiment of a method for manufacturing a synthetic resin biaxially stretched tube with an enlarged diameter portion according to the present invention in the order of steps.

FIG. 2 is a schematic view showing the next step of FIG. 1 in the order of steps.

FIG. 3 is a cross-sectional view of a biaxially stretched synthetic resin pipe with a socket obtained by the manufacturing method shown in FIGS. 1 and 2;

FIGS. 4A and 4B are schematic diagrams schematically illustrating an expansion / contraction mechanism of an expansion / contraction die used in the manufacturing method shown in FIGS. 1 and 2, wherein FIG. 4A is in a contracted state, and FIG. It represents.

FIG. 5 is a schematic diagram schematically illustrating a modified example of an expansion and contraction mold used when carrying out the method of manufacturing a synthetic resin biaxially stretched tube with an enlarged diameter portion according to the present invention, wherein FIG. The contracted state, and FIG. 3B shows the enlarged state.

FIG. 6 is a schematic view schematically illustrating an expansion / contraction mechanism of a modification of an expansion / contraction die used in carrying out the method of manufacturing a synthetic resin biaxially stretched tube with an enlarged diameter portion according to the present invention. (a) shows a contracted state, and (b) of the same figure shows an enlarged state.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Synthetic resin biaxially stretched original tube 2 Auxiliary mold 3, 30 Expansion / contraction die 31 Shrinkage prevention part 32 First expansion / contraction part 33 Second expansion / contraction part 34 Third expansion / contraction part 35 Fourth expansion / contraction part 36 Large expansion / contraction member 37 Small expansion / contraction member 38 Slide shaft 39 Slide member 4a, 4b Restriction member 5 Synthetic resin biaxially stretched tube with receiving port (synthetic resin biaxially stretched tube with enlarged diameter portion) 51 Receiving port (expanded diameter portion) 53 Tube main body 6 Elastic material

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 3H111 AA01 BA15 BA34 CB02 CB28 CC19 DA26 EA12 4F209 AG08 AG23 AJ09 AR06 AR20 NM02 NN02 NP01 4F210 AG08 AG23 AJ09 AR06 AR20 QC05 QD25 QD50 QG04

Claims (10)

[Claims] 1. A synthetic resin biaxially stretched raw tube having an enlarged diameter portion having an enlarged portion formed by partially expanding the diameter of the synthetic resin biaxially stretched original tube. An expansion ratio characterized by satisfying the following relationship: extension ratio in the axial direction ≦ extension ratio in the axial direction of the enlarged diameter portion, extension ratio in the circumferential direction of the synthetic resin biaxially stretched raw tube ≦ extension ratio in the peripheral direction of the enlarged diameter portion. A biaxially stretched synthetic resin tube with a diameter. 2. A mold for forming a large-diameter portion, wherein the large-diameter portion is deformed into an external shape along the internal shape of the large-diameter portion to be obtained from the external shape along the substantially internal shape of the synthetic resin biaxially stretched raw tube. Is inserted into the enlarged-diameter portion forming portion of the synthetic resin biaxially stretched original tube, and the enlarged-diameter portion forming portion is heated to the temperature at which the synthetic resin can be oriented. The synthetic resin biaxially stretched tube with an enlarged diameter portion according to claim 1, wherein the enlarged diameter portion is formed by deforming the mold into an outer shape along the inner surface shape of the enlarged diameter portion. 3. The synthetic resin is an amorphous resin, and has an alignable temperature equal to or higher than the glass transition temperature (glass transition temperature + 40).
3. The biaxially stretched synthetic resin tube according to claim 2, wherein the temperature is not higher than (° C). 4. The synthetic resin is a crystalline resin, and has an alignable temperature of not less than a melting point (melting point + 40 ° C.).
The biaxially stretched synthetic resin tube according to any one of claims 1 to 4, wherein 5. An enlarging / reducing mold for forming an enlarged-diameter portion which is deformed into an outer shape along an inner surface shape of a diameter-enlarging portion to be obtained from an outer surface shape along an approximately inner surface shape of a synthetic resin biaxially stretched raw tube. After the enlarged diameter portion is heated to the temperature at which the synthetic resin can be oriented while being inserted into the enlarged diameter portion of the original biaxially stretched tube, the enlarged diameter is obtained while maintaining the heated state. A method for producing a synthetic resin biaxially stretched tube with an enlarged diameter portion, comprising a step of forming an enlarged diameter portion for enlarging and deforming the outer shape along the inner surface shape of the portion. 6. An auxiliary die having an outer diameter substantially equal to the inner diameter of the synthetic resin biaxially stretched original tube is inserted into the enlarged diameter portion forming portion before the expansion and contraction mold is inserted into the synthetic resin biaxially stretched original tube, and can be oriented. After the preheating step of heating the enlarged diameter portion forming portion to a preheating temperature lower than the temperature, the auxiliary mold in the enlarged diameter portion forming portion in the preheated state is replaced with an enlarging / reducing mold, and the enlarged diameter portion forming step is performed. 6. The method for producing a biaxially stretched synthetic resin tube having an enlarged diameter portion according to 5. 7. The shrinkage of the synthetic biaxially stretched raw pipe in the axial direction by restricting both ends of the synthetic biaxially stretched raw pipe with a regulating member at least during the step of forming the enlarged diameter portion. 5. The method for producing a synthetic resin biaxially stretched tube with an enlarged diameter portion according to item 4. 8. The synthetic resin is an amorphous resin, and has an alignable temperature equal to or higher than the glass transition temperature (glass transition temperature + 40).
The method for producing a synthetic resin biaxially stretched tube with an enlarged diameter portion according to any one of claims 5 to 7, which is not higher than (° C). 9. The synthetic resin is a crystalline resin, and has an alignable temperature of not less than a melting point (melting point + 40 ° C.).
A method for producing the synthetic resin biaxially stretched tube with an enlarged diameter portion according to any one of claims 1 to 7. 10. The expansion / contraction die is inserted into the enlarged-diameter portion forming portion of the synthetic resin biaxially stretched original tube while the outer peripheral surface of the expansion / contraction die is covered with an elastic material. A method for producing the synthetic resin biaxially stretched tube according to claim 9.